DE69219180T2 - Ink jet recording system and method - Google Patents

Description

The invention relates to an ink jet recording system or an ink jet recording apparatus, in particular to a structure and a method for maintaining a high ink ejection performance.

In recent years, personal computers and automatic office equipment such as word processors have been widely used, and a recording device has also been widely used as an output device for the processing results obtained by these devices. A dot matrix printing method, a thermal printing method, and an ink jet recording method are each well known as a recording method used in the recording device.

The ink jet recording method has several advantages such as the usability of various types of recording medium such as a plain untreated paper and a transparent recording sheet for overhead projection and the fact that the noise level generated during the recording operation is relatively low. One of the ink liquid ejection methods used in the recording head for the ink jet recording method is based on ejecting the ink liquid by the pressure wave associated with the growth and shrinkage of the bubble generated by the thermal energy in the ink liquid. The recording heads using this ejection method are often constructed in the following manner.

(1) Producing a plurality of heat generating elements for generating heat energy and driving means for driving the heat generating elements for generating of thermal energy on a substrate made of silicon materials and the like in a production process similar to semiconductor device manufacturing.

(2) forming a plurality of ink channels by joining the above-mentioned substrate and a top plate having channels, each ink channel corresponding to the nozzle and used for a chamber in which heat energy is transferred to the ink liquid, a plurality of nozzles each provided at the open end part of each ink channel and used for ejecting the ink liquid, and a common liquid container arranged on the opposite side of the nozzle array front surface of each ink channel and arranged for holding the ink liquid for supplying the ink liquid to each of the ink channels.

In addition to the advantages obtained by the ink jet recording method, it is welcome that the images recorded on the recording medium using this type of recording head can be displayed more clearly and finely because the nozzle structure can be formed with high fineness and accuracy. In addition, the size of the recording head itself can be made small, and the manufacturing and material costs can be reduced. In this respect, the recording head which ejects ink liquid using heat energy as described above has been widely used in various types of recording apparatus in recent years.

In the case of such a recording head as the above-described recording head which has a relatively fine nozzle and a relatively fine ink passage, an influence of the viscosity of the ink liquid on the ejection performance of the recording head is relatively large. For example, when the ink liquid in the ink passage near the nozzle becomes higher in viscosity due to evaporation of the solvent of the ink liquid, there may be a case that the ink liquid having higher viscosity the flow of the ink liquid when ejecting the ink liquid is impaired, resulting in the defective ink ejection such as the deflection of the ejected ink liquid and the reduction in the amount of the ejected ink liquid and even the failure of the ejection of the ink liquid. Further, in the case where unnecessary ink droplets and an undesirable substance such as paper powder adhere to the nozzle array front surface of the recording head, the deflection of the ejected liquid may occur and hence the quality of the recorded images may be deteriorated. In the ink jet recording method, since the ink liquid is ejected from the recording head onto the recording medium such as a paper sheet and a transparent recording sheet, the ink mist composed of fine ink droplets may occur and the excessive amount of the ejected ink liquid may be rejected from the recording medium. As shown in Fig. 1, this ink mist and the rejected ink liquid adhere to the nozzle array front surface 1 of the recording head, and if this adhered ink liquid accumulates too much around the nozzles 12, the ejection operation may be impaired and the ejection direction may deviate, and even the ejection operation may be stopped. Also, due to the temperature difference between the recording head and the room air, condensed water drops may adhere to the nozzle array front surface 1, resulting in the same adverse effects as in the case where the ink liquid adheres to the recording head.

With respect to the above-described failures of ink ejection due to the increase in viscosity of ink liquid and the drops of ink liquid adhering to the nozzle array front surface, various types of operations for preventing these failures and avoiding the causes of these failures to ensure reliable ink ejection operations are known as ejection recovery operations.

One of these ejection recovery operations, which aims at preventing the ejection failure mainly due to the increase in viscosity of the ink liquid, is known, for example, as a capping operation in which a cap formed appropriately covers the front surface on which the nozzle of the recording head is formed (the nozzle array front surface) to prevent the water in the ink liquid from evaporating from the nozzle. There is known a suction recovery operation in which the difficult-flowing ink liquid outside the recording head is removed by sucking the ink liquid from the nozzle by applying suction pressure inside the cap fitted on the recording head. In addition, a pressure recovery operation is known as a substitute for the suction recovery operation or a combination with the suction recovery operation, in which the ink liquid is pressurized from the ink supply side of the ink channel and is discharged from the nozzle. In addition, as another discharge recovery operation, a discharge operation is known in which the heavy-flowing ink liquid in the recording head is discharged by discharging the ink liquid not used for recording the information or images on the recording media, which is called an idle discharge operation. The above-described discharge recovery operations are not only for removing the heavy-flowing ink liquid but also for removing bubbles in the ink liquid which exert adverse effects on the ink liquid discharge performance.

As one of the ejection recovery operations aimed at preventing the ejection failure mainly due to undesirable substances adhering to the recording head, a structure is known in which the nozzle array front surface is kept clean to prevent the deviation of the ejection direction. In a typical structure, a wiping member is arranged so that the wiping member contacts the nozzle array front surface and is moved relative to the front surface. As a result, the droplets of the ink liquid on the nozzle array front surface can be wiped off.

Undesirable substances such as unnecessary ink liquid adhering to the nozzle array front surface are generated by ink mist formed when the ink liquid is ejected and the ink liquid discharged from the recording sheet in the recording operations of the recording head and by paper dust which may adhere to the recording head when the recording head and the paper sheets move relative to each other in the recording operation.

Even in the ink jet recording apparatuses which perform the above-described various types of ejection recovery operations, in the case where the recording head has not been used for ejecting ink liquid for a long period of time, a certain amount of water in the ink liquid may inevitably evaporate and the ink liquid may become increasingly difficult to flow. In this case, an ink ejection failure may occur in a recording head at the start of recording operations after a long period of time in which the recording head has not been used. Therefore, in the conventional ink jet recording apparatus, in order to prevent the above-described failures of ink ejection, it is necessary to perform the suction operation at the start of the recording operation so that the predetermined recovery operations are performed due to the high viscosity of the ink liquid, and the ejection recovery operations are performed for 5 to 30 seconds until the start of the recording operation can be permitted.

The failure of the ejection of the ink liquid fed into the recording head caused by the poorly flowing ink liquid and the recording head has not been used for recording operations for such a long period of time as several days to one year can be avoided only by a single suction recovery operation, and after this operation is performed, the recording head can be used for the recording operation for several days to one week without recovery operations such as suction operation which requires a relatively long period of time before the recording operation can be restarted. However, in the case that the ordinary sheet paper is used as a recording medium, the application of rapid drying of the ink liquid is made for fixing the ink liquid on the recording medium, and the recording operation is often carried out at high temperature and low humidity. In such a case, even in the capping operation with the cap over the recording head, the ink liquid in the recording head dries out rapidly, and the viscosity of the ink liquid may increase in a relatively short period of time. If so, it is necessary to carry out the idle ejection operation before and during the recording operation in order to prevent the failure of ejection of the ink. In addition, in such an environment, when the period of time during which the recording head is not used is so long, the difficult-flowing ink liquid cannot be completely removed only by the idle ejection operation.

With respect to the above-mentioned problems caused by the ink liquid that is difficult to flow, in the conventional ink jet recording apparatus, the sealing of the recording head by the cap is more reliable, and materials through which the least amount of liquid or vapor passes are used for the cap. However, even if these conventional caps are used, the ink liquid that is difficult to flow cannot be completely prevented, and therefore, such a special ejection recovery operation as a Suction operation, etc., required before recording operation.

In case of using a cap which provides hermetic sealing, the following problems occur particularly in the portable recording device.

1. Since the recording head is covered by the cap, due to the pressure change in the cap caused by the vibration and the shock during transportation, the meniscus formed in the ink channel near the nozzle falls back into the inside of the ink channel, which leads to a loss of ink liquid in the ink channel and may cause failure of ink ejection.

2. Due to the change in the temperature of the atmosphere and the change in the temperature of the recording head, the air inside the cap may expand or contract, and therefore there is still a problem that the meniscus falls back into the inside of the ink channel and the ink liquid may leak out of the nozzles due to suction.

With respect to the above-mentioned problem caused by the pressure fluctuation, there is proposed an ink jet recording apparatus comprising:

- a cap half open to the atmospheric air,

- a recovery system and

- a waste ink tank to solve this problem by the patent application of the applicant of the present invention. However, even in this device, the above-mentioned problem of the ink liquid being difficult to flow cannot be completely eliminated.

In view of the reliability of the recovery operations in the case where the gap formed between the cap and the recording head due to paper powder and dust adhering to the cap and the nozzle assembly front surface of the recording head is formed as described above, the evaporation of the solvent component of the ink liquid is further increased, and accordingly, it is considered that the failure of ink ejection is liable to occur.

On the other hand, in the ejection recovery operation using the above-mentioned wiping structure, there are substances remaining on the nozzle array front surface such as ink liquid and paper powder which are not wiped off by the sheet. In the case that the ink liquid, etc., remain on the nozzle, the liquid components of the ink liquid evaporate and the ink liquid becomes increasingly difficult to flow and paper powder adheres to the nozzle array front surface, and therefore, after a long period of time, the solidified ink liquid and paper powder cannot be removed even by the wiping operation with a sheet. In the case where the ink liquid contains dyes and solvents which have a property of becoming increasingly difficult to flow or crystallizing, a phenomenon is observed that the difficult to flow ink liquid is deposited near the nozzle as the evaporation of the liquid components in the ink liquid progresses and that the nozzle is covered by the solidified ink liquid, which may result in failure of ink ejection.

The difficult-flowing ink liquid remaining on the nozzle array front surface and the solidified ink liquid built up near the nozzle cannot be removed only by the ordinary wiping operation with the blade and the idle ejection operation of the ink liquid. Before the idle ejection operation, failures in ink ejection may frequently occur even if the ink liquid is heated up to an optimum temperature used for the recording operation of the recording head, and therefore, in such a case, the difficult-flowing ink liquid remaining near the nozzle Ink liquid is forcibly drained in many prior art devices. However, in such a case of recovery by forcibly draining the ink liquid in a suction operation, some unsolved problems become apparent with respect to clogging of the storage means such as a waste ink tank in response to the drained amount of ink liquid and reduction of the effective amount of ink liquid to be used for the recording operation.

An object of the present invention is to reduce the above-mentioned problems.

Patent Abstracts Japan, Vol. 11, No. 102 (M-576) [2549] dated March 31, 1987 and Patent Document No. JP-A 61-249 758 as well as Patent Abstracts Japan, Vol. 11, No. 330 (M-636) [2777] dated October 28, 1987 and Patent Document No. JP-A 62-113 561 describe ink jet recording heads having a heating device and a cleaning device for wiping a front surface of the ink jet recording head.

According to a first aspect of the present invention, there is provided an ink jet recording apparatus according to claim 1.

According to a second aspect of the present invention, there is provided a recovery method for the ink jet recording apparatus according to claim 10.

The embodiments of the invention are described below by way of example and with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a state in which undesirable substances adhere to the nozzle assembly front surface,

Fig. 2 is a perspective view of an example of an ink jet recording apparatus to which the present invention is applicable,

Fig. 3A and Fig. 3B show a bottom view and a top view, respectively, of a part in the vicinity of the carriage with the recording head shown in Fig. 2,

Fig. 4A, Fig. 4B and Fig. 4C show wiping operations which are carried out in the recording device shown in Fig. 2,

Fig. 5A and Fig. 5B show enlarged views of the wiping operations shown in Fig. 4A, Fig. 4B and Fig. 4C,

Fig. 6 is a block diagram showing an embodiment of the control system in the ink jet recording apparatus of the first embodiment of the present invention,

Fig. 7A and Fig. 7B are flowcharts showing an example of the recording control processes in the ink-jet recording apparatus of the first embodiment of the present invention,

Fig. 8 shows a flowchart of an embodiment of the timer recovery process in the processes shown in Fig. 7A and Fig. 7B,

Fig. 9 shows a flowchart of an embodiment of the wiping operation and the capping process in the processes shown in Fig. 7A and Fig. 7B,

Fig. 10A and Fig. 10B show flow charts of two embodiments of the standby processes in the processes shown in Fig. 7A and Fig. 7B,

Fig. 11 shows a flowchart of an embodiment of the forced recovery process in the processes shown in Fig. 7A and Fig. 7B,

Fig. 12 shows a flowchart of an embodiment of the counter recovery process in the processes shown in Fig. 7A and Fig. 7B,

Fig. 13 is a perspective view of an ink-jet recording apparatus of the second embodiment of the present invention,

Fig. 14A shows a perspective view of the components of a suction pump shown in Fig. 13 in a disassembled state, and Fig. 14 shows a perspective view of a piston of the suction pump shown in Fig. 13,

Fig. 15 shows a sectional view of the suction pump shown in Fig. 13,

Fig. 16 is a block diagram showing the control logic of the ink jet recording apparatus shown in Fig. 13,

Fig. 17A and Fig. 17B are flow charts showing the processes in the ink jet recording apparatus shown in Fig. 13 in application of the present invention,

Fig. 18 shows a schematic diagram of an embodiment of an apparatus equipped with the ink-jet recording apparatus according to the invention, and

Fig. 19 schematically shows a block diagram of an embodiment of a portable printing device according to the present invention.

FIRST EMBODIMENT

Fig. 2 shows a schematic view of an ink jet recording apparatus of the first embodiment of the present Invention. The component C is an ink jet cartridge which integrally comprises an ink tank part on the upper side of the figure and a recording head on the lower side of the figure, all of which are arranged in a single unit, and further comprises a connector member for receiving the signals for driving a recording head. In this embodiment, the recording head has a plurality of nozzles directed downward in the figure, and elements for generating energy used for ejecting ink liquid are arranged in the respective ink channels connected to the nozzle. In addition, each of the ink channels is connected to the common liquid tank in which the ink liquid supplied from the ink tank part is stored. With respect to the energy generating element, electricity-heat conversion elements for generating the heat energy are preferred because of the small size of the nozzle and the ink channel.

The component 2 is a carriage having four cassettes C1, C2, C3 and C4 in their designated positions, each of the cassettes corresponding to a single color of ink, e.g. yellow, magenta, cyan and black, and a connector holder for transmitting the electrical signals for driving the recording heads. Absorbers are arranged in the lower part of the carriage 2 as described below so that each recording head is arranged between adjacent absorbers.

The component 11 is a guide rail which extends in the direction of movement of the carriage 2 and supports the carriage 2 so that the carriage 2 can move freely on the guide rail. The component 52 is a drive belt which transmits a driving force for reciprocally moving the carriage 2 on the guide rail 11. A pair of transport rollers 15 and 16 and a pair of transport rollers 17 and 18 are arranged respectively in front of and behind the recording surface defined by the carriage 2, and are used to support a recording medium and for applying a transport force to the recording medium. The component P is the recording medium, e.g. a separated sheet of paper, which is pressed onto a pressure plate not shown in Fig. 2 to form a flat base for recording the information on the recording medium. A recording head part of the ink jet recording cartridge C, which is arranged on the carriage 2, extends downward from the carriage 2 in the figure and is arranged between the transport rollers 16 and 18 so that a nozzle arrangement front surface of the recording head part can be arranged opposite and parallel to the recording medium P which is pressed onto the pressure plate not shown in Fig. 2.

In the ink jet recording apparatus of this embodiment, a recovery system unit 200 used for a recovery process is arranged in the home position on the left side in Fig. 2. In the recovery system unit 200, a component 300 of a capping unit is arranged corresponding to each of a plurality of ink jet cartridges with recording heads, and the capping unit 300 is movable in the width direction in which the carriage 2 moves in response to the movement of the carriage 2, and can move upward or downward in the height direction according to its movement in the width direction. When the carriage 2 is located at the home position, the capping unit 300 contacts the recording head part and covers the nozzle array front surface of the recording head, so that the ink liquid in the nozzle of the recording head does not evaporate or become increasingly difficult to flow and does not become solid, all of which lead to failures in ink ejection.

The component 500 in the recovery system unit 200 is a pump unit which is connected to the capping unit 300 and used to generate a suction force between the capping unit 300 and the recording head. is formed when both are in contact with each other during the recovery operation so as to drain the ink liquid in case of failures in ink ejection in the recording head. The pump unit 500 has an opening and closing mechanism for connecting a part connected to the inside of the capping unit 300 and the outside air. By this structure, in case the capping unit 300 caps the recording head, the inside of the capping unit can be opened to the outside air. This structure is applicable to the process shown in Fig. 10B which will be described later. In the recovery system unit 200, the member 401 is a blade used as a wiping member made of elastic materials such as rubber. B. rubber, and the member 402 is a sheet holder for supporting the sheet 401. In this embodiment, the sheet 401 supported by the sheet holder 402 can be placed by the sheet lifting mechanism driven by the movement of the carriage 2 either in a wiping position in which the sheet 401 is moved upward and used to wipe the ink liquid on the nozzle array front surface of the recording head, or in a waiting position in which the sheet is moved downward so that the sheet 401 cannot act on the nozzle array front surface of the recording head.

Further, in this embodiment, the wiping operation by the blade 401 is performed only when the carriage is moved from the left side, that is, from the side of the home position where the recovery system unit is arranged, to the right side in Fig. 2. That is, since the blade 401 is arranged between the capping unit 300 and the paper feed part for feeding a recording medium P, in the case of wiping the recording head, since the blade 401 moves from the right side to the left side, there may be a case that the ink liquid wiped in the wiping operation is splashed on the paper feed part by the excessive elastic force developed by the blade 401 and the recording medium contaminated by ink liquid. If such a case as described above does not occur, the wiping operation may be carried out in one direction or in both directions.

With respect to the above-described wiping operation by the capping unit 300 moving up and down and reciprocally for the capping operation and the blade 401 moving up and down, and controlling the direction in which the blade 401 moves in the wiping operation, for example, a mechanism as described in Japanese Patent Document No. 126655/1990 (No. 122878/1989 based on Japanese priority) is applicable. The capping operation and the wiping operation can be carried out by the combination of the driving elements such as the motors and solenoids for moving the capping unit 300 and the blade 401 up and down, and a controller for driving the driving elements.

Fig. 3A shows a bottom view of the carriage 2, and Fig. 3B shows a front view of the carriage 2. In these figures, the member 1 is a nozzle array front surface, and the member 12 is a nozzle from which ink droplets are ejected. The member 3 is an absorber used as a cleaning means for the blade 401, which is made of porous materials which are corrosion-resistant to the ink liquid and have a high absorbency. The absorber 3 for cleaning the blade is arranged on both sides of the nozzle array front surface 1 of each recording head. As shown in Fig. 3B, in order to prevent the absorber 3 for cleaning the blade from rubbing against the recording medium P, the absorber 3 for cleaning the blade is arranged a little inward of the nozzle array front surface 1 of each recording head which extends below the lower surface of the carriage 2. It is desirable that the material used for the absorber 3 for cleaning the sheet does not expand even if it absorbs the ink liquid absorbed to prevent the absorber 3 from rubbing against the recording medium to clean the sheet.

(wipe operation)

It is well known and described above that the front surface of the recording head is wetted by the ink liquid when recording images by ejecting ink liquid as described above. In the case where an excessive amount of ink liquid adheres to the adjacent surface of the nozzle, the usual ejection operations of the ink liquid are not fully achieved: the ejection direction of the ink liquid is deviated, and finally even the ink liquid cannot be ejected. In order to prevent these undesirable and abnormal operations in ejecting the ink liquid, it is desirable to wipe the nozzle array front surface 1 regularly.

Referring to Fig. 4 and Fig. 5, the wiping operations in this embodiment will be described below.

In Fig. 4, a running action of the sheet 401 in the wiping operations is shown, and the enlarged view is shown in Fig. 5. As described above, the wiping operations are carried out while the carriage 2 is moved from the home position (on the left side in Figs. 2 and 4) to the recording medium supply system side (on the right side in Figs. 2 and 4).

Fig. 4A shows a state of the carriage 2 and the blade 401 at the start of the wiping operations. In this state, the blade 401 extends from the waiting position in the Y direction indicated by the arrow and is fixed at a predetermined position, that is, a wiping position, the extension length of the blade 401 being adapted for wiping the recording head. Then, as shown in Fig. 4B and Fig. 4C, when the carriage 2 with the cassettes C is horizontally moved from left to right, the blade 401 alternately contacts the absorbers 3 arranged on the lower surface of the carriage 2 and the nozzle array front surface 1 of the recording head extending under the carriage 2, and thus the blade 401 removes the excess ink liquid adhering to the nozzle array front surface 1 and is also cleaned by the absorber 3 for cleaning the blade, as shown in Fig. 5A and Fig. 5B. After completing the wiping operation of all the nozzle array front surfaces 1 and the absorber 3 for cleaning the blade, the blade 401 is returned in the Y' direction and fixed in the waiting position. By disposing the absorbers 3 for cleaning the sheet between the recording head, the ink liquid removed from the nozzle array front surface 1 by the sheet 401 can be captured and absorbed by the absorber 3 for cleaning the sheet, and therefore the ink liquid remaining on the sheet 401 can be reduced, so that the mixing of the ink colors in the next wiping operation of the nozzle array front surface 1 of the recording head when using different colors can be prevented in a very effective manner.

The moving speed of the carriage 2 for the wiping operations is determined in consideration of the surface to be wiped by the sheet, which is defined as the convex and concave shapes formed by the nozzle array front surface 1 and the absorber 3, and in consideration of the flexibility of the sheet 401 formed as an elastic body. The higher the speed increases, the less the contact between the sheet 401 and the nozzle array front surface 1 or the absorber 3 for cleaning the sheet, which occurs due to the delay in following the shape of the sheet 401 in the above-mentioned convex and concave shapes, resulting in a reduction in the effect of removing the excess ink liquid or undesirable foreign matter, and therefore the speed for the wiping operations is preferably relatively low. In connection with this invention, it has been found that a speed equal to or less than 300 mm/s does not cause any problem.

(tax system)

Fig. 6 shows an example of the structure of the control system in the first embodiment.

The device 800 in Fig. 6 is a controller, which forms a main part of the control part having a CPU 801 and executing the processes shown in Figs. 7 - 12, which is realized by, for example, a microcomputer, a ROM 803 which stores programs corresponding to these processes and other fixed data, and a RAM 805 for storing the image data and the update data. In the controller 800, a set of timers 807 are arranged, which are used for determining the time period for controlling the ink ejection recovery processes in an appropriate sequence. The device 810 is a host unit, such as a memory card 812. B. a reading device which is used to provide the image data, and the image data as well as the control commands and status message signals are transmitted through an interface I/F 812 between the host unit and the control device 800.

A switch set 820 includes a power switch 822, a copy switch 824 for requesting the start of the recording of the information, and a recovery switch 826 for requesting the start of the ink ejection recovery operations, all of which accept the input request by the operator. A sensor set 830 is used for detecting various states of the device, which includes a sensor 832 for detecting the position of the carriage 2 in the home position or the start position, and a sensor 834 for detecting the position of the suction pump.

The component 840 is a recording head driver for driving the elements, the electro-heat conversion elements in this embodiment, which are arranged in the recording head 86 of the cartridge C and are used for generating heat energy for ejecting ink liquid. The component 850 is a main scanning motor for moving the carriage 2 in the main scanning direction (the width direction in Fig. 2). The component 852 is a driver for the main scanning motor 850. The component 860 is a sub-scanning motor for rotating the rollers 15, 16 and 17, 18 (shown in Fig. 2) and transporting the recording medium, and the component 862 is its driver.

The device 870 is a recording head heater for heating the recording head, which may be realized as a single unit formed together with the recording head or as a separate unit formed on the substrate on which an electricity-heat conversion element is formed in a manufacturing process common to both. The recording head heater 870 may be arranged in the carriage 2, in which the arrangement position in the carriage is determined so as to achieve effective heat transfer by the contact of the recording head heater with the recording head 86 when arranging the head unit in the cartridge.

(Ejection recovery mode)

Various types of ejection recovery modes used in the apparatus of this embodiment will be described below.

(a) Ejection recovery mode determined by the recovery switch 826

The purpose of this recovery mode is to restore the ejection capability of the recording head to a normal state at the time when the operator turns on or presses the recovery switch 826, taking into account that the ejection operation of the recording head is not normally carried out although the scheduled recovery operations have been automatically completed in the apparatus of this embodiment. Although this mode is not used under ordinary operation conditions, and when it is used, it is more comprehensively carried out than the other modes.

In this mode, the ink liquid which has become difficult to flow and bubbles in the common liquid tank or in the ink channel can be removed by suction with the pump 500. In addition, by driving the electricity-heat conversion element to discharge simultaneously with driving the pump 500 to suck the ink liquid, adding the pressure generated by the pump 500 and the pressure which is instantaneously developed by the growth and contraction of the bubble caused by the electricity-heat conversion element, the bubbles in the common liquid tank or ink channels can be effectively removed. Furthermore, since the electrothermal conversion element for generating the bubble is driven to eject the ink liquid, so that the temperature of the ink liquid in the ink channels increases and therefore the viscosity and surface tension of the ink liquid are reduced and the resistance of the ink channel is also reduced, bubbles in the ink channel can be easily removed. The parameters for the recovery mode are determined depending on the number of nozzles, the dimensions of the components of the recording head and the viscosity of the ink liquid. In this embodiment, the suction pressure is determined by the maximum pressure generated by the pump 500, the time period of the suction operation is 2.5 s, and the amount of the ink liquid to be sucked is about 0.17 g.

After the suction operation, the nozzle array front surface of the recording head is wiped by the rubber blade, and an idle ejection operation of the ink liquid is carried out.

(b) Ejection recovery mode using the timer suction operation

The object of this mode is to prevent the case that the ejection performance of the recording head is not in a normal state due to an increase in the viscosity of the ink liquid and the growth of the bubbles formed in the common liquid tank in the recording head after a long period of time has passed in which the recovery operation has not been carried out. In this mode, the next recovery operation is carried out at a fixed time determined by the timer arranged in the controller after the previous recovery operation has been carried out.

In this mode, the ink liquid which has become difficult to flow and has bubbles in the common ink tank or the ink channel can be removed by suction with the pump.

After the suction operation, the wiping of the nozzle array front surface of the recording head by the blade 401 and the idle ejection operation of the ink liquid are carried out.

(c) Ejection recovery mode using the counter

The purpose of this mode is to prevent the case that the ejection performance of the recording head is reduced due to an increase in viscosity of the ink liquid and the growth of the bubbles formed in the common liquid container in the recording head. after a long period of time has passed in which the retrieval operation has not been carried out and the information recording operation has been continued for a long time, is not in a normal state. In this mode, the next retrieval operation is carried out at the time when the number of the printed, separated recording documents reaches a predetermined number while the number of the printed, separated recording documents is counted by the counting means after the previous retrieval operation has been carried out.

This mode is similar to the above-described mode using the timer suction recovery operation, when the ink liquid which becomes increasingly difficult to flow and the bubbles in the common liquid tank or the ink channels can be removed by suction by the pump, and after the suction operation, the nozzle array front surface of the recording head is wiped by the blade 401 and the idle ejection operation of the ink liquid is carried out. In this respect, the timer and the counter are started when the timer suction recovery operation by the previous mode or the counter recovery operation after this mode is carried out.

(d) Provisional Ejection A Mode

In this preliminary ejection mode, the idle ejection operation of the ink liquid from all nozzles is carried out each time before the recording operation, when the recording operation is stopped, after waiting for the next recording operation, and when the wiping operation is performed. In this mode, in order to achieve stable conditions for ejecting the ink liquid without increasing the temperature of the ink in the ink channels, for example, the driving frequency of the electricity-heat conversion element of 1 kHz is applied in response to the maximum Control frequency of 4 kHz of the electricity-heat conversion element.

(e) Preliminary ejection (B) mode

In this preliminary ejection operation, the inks are ejected from all the nozzles simultaneously with the execution of the suction operation. In this mode, the driving frequency of the electricity-heat conversion element is set to 4 kHz, which is the maximum driving frequency of the electricity-heat conversion element, so that the temperature of the ink channel can be increased to reduce the viscosity of the ink and increase the ejection speed of the ink in the ink channel by using the ejection energy.

(f) Preliminary ejection (C) mode

This preliminary ejection operation is carried out in the case where more difficult-flowing liquid exists on the nozzle array front surface or near the nozzle. After a preliminary heating (B) mode described below, the driving of the electricity-heat conversion element in the ejection operation is carried out at its maximum driving frequency. In this mode, the driving frequency of the electricity-heat conversion element is set to 4 kHz which is equal to the maximum driving frequency of the electricity-heat conversion element, so that the temperature of the electricity-heat conversion element can be increased and the viscosity of the ink liquid can be reduced to achieve an easy ejection operation of the ink liquid.

(g) Recording head heating mode

The recording head heating mode is for maintaining the temperature of the recording head 86 at a desired value for ejecting the ink liquid by using the heater 870 which is different from the electricity-heat conversion element and is used as a heater for ejecting the ink liquid. This mode is executed at the time when the recording operation is performed or when the recording head is waiting for the next recording operation at a fixed timing, that is, at a standby timing.

(h) Preliminary heating (A) mode

This preliminary heating operation is carried out before a preliminary ejection operation is to be carried out in the case that the recording head is not operated for a predetermined period of time. In this mode, the heater (the electricity-heat conversion element) used for ejecting the ink liquid is caused to generate heat energy which is low enough not to eject the ink liquid. The temperature of the ink liquid in the ink channel is raised to a desired value for the ejection operation. The reason why the heater for ejecting the ink liquid is used in this mode is that the heater for ejecting the ink liquid is in direct contact with the ink liquid in the ink channel and therefore the heating of the ink liquid can be carried out efficiently and immediately. The heater 870 which is arranged differently from the heaters for ejecting the ink liquid is usable in this mode. First of all, the temperature of the ink liquid is controlled to be the same as that in the recording head heating mode.

(i) Preliminary heating (B) mode

This preliminary heating operation is carried out before the wiping operation or the preliminary ejection (C) mode operation is to be carried out after the recording head is not operated for a specified period of time. In this mode, the heater is used to eject The ink liquid is influenced to generate heat energy low enough not to eject the ink liquid. The temperature of the ink liquid in the ink channel is raised to a desired value for the ejection operation. The reason why the heater for ejecting the ink liquid is used in this mode is that the heater for ejecting the ink liquid is in direct contact with the ink liquid in the ink channel and therefore the heating of the ink liquid can be carried out efficiently and immediately. The heater 870 which is arranged differently from the heaters for ejecting the ink can be used in this mode.

(Recovery control processes in the recording device)

The recovery control processes that specifically apply the above-mentioned modes are described below.

Fig. 7A and Fig. 7B show an embodiment of the main control processes of the ink-jet recording apparatus, with the recovery processes mainly described.

In step S1, when the main switch 822 is turned on, the ink jet recording apparatus of this embodiment first checks each part of the apparatus, such as the ROM 803 and the RAM 805, etc., as a start-up check of the recording apparatus itself.

Subsequently, in step S3, a recovery operation is performed by the timer recovery processes described below with reference to Fig. 8, and then in step S5, a preliminary discharge (A) mode operation described above is carried out. In these timer recovery processes, there may be a case that the discharge recovery mode is started using the timer recovery process. Suction mode or an operation to remove the difficult-flowing ink liquid is included.

After step S5, the wiping and capping operations described below with reference to Fig. 9 are carried out in step S7, and in step S9, the recording device waits for the signal for requesting the start of the recording operation. If step S9 does not detect a signal for requesting the start of the recording operation, step S11 is selected to judge whether or not the retrieval switch 826 is on. If step S11 judges that the retrieval switch 826 is not on, then step S13 is selected for the standby process explained below with reference to Figs. 10A and 10B, and if the retrieval switch 826 is on, step S15 is selected to execute the compulsory retrieval process described below with reference to Fig. 11.

On the other hand, if a signal for requesting the start of the recording operation is detected in step S9, the selection of step S17 is made to judge whether the cap is closed, that is, whether the cap is fitted or not. If the cap is fitted, the timer retrieval process is carried out in step S19 as described below with reference to Fig. 8, and thus, if the cap is not removed, the cap is removed in steps S21 and S22. After step S23, there follow step S25 for the wiping operation and step S27 for the above-mentioned preliminary ejection (A) mode operation, and step S29 is reached.

If step S17 judges that the cap is opened, step S31 is then selected and judges whether or not a predetermined period of time, e.g. 12 seconds, has passed since the cap is opened. If step S31 concludes negatively, step S29 is immediately selected. If step S31 concludes that a predetermined If a predetermined period of time has passed, the preliminary ejection (A) mode operation is carried out in step S33, and it is judged in step S35 whether or not a predetermined period of time, e.g., 60 seconds, has passed after the cap is opened. If step S35 comes to a negative conclusion, step S29 is reached. If not, the wiping operation is carried out in step S37 before step S29 is reached.

In step S29, a timer for counting a predetermined period of time of 4 hours is reset as one of counters used for an appropriate retrieval process in response to a predetermined timing. This timer is designed as a 4-hour timer. After step S29, the recording operation is carried out in step S39. After step S39, the counter retrieval process described below with reference to Fig. 12 is carried out in step S41, and step S9 is reached again to detect a signal for requesting a start of the recording operation. In step S41 for the counter retrieval process, the ejection retrieval mode using the counter may be included.

Fig. 8 shows an embodiment of the timer recovery process executed in steps S3 and S19. In step S51, a relatively long period of time, e.g., 72 hours, is counted using a timer which is one of the timers used for the recovery operation and is designed as a 72-hour timer, which judges whether or not 72 hours have passed since the previous recovery operation by sucking the ink liquid. If step S51 comes to a negative conclusion, step S53 is selected as the next step to judge whether or not 4 hours have passed since the previous preliminary ejection recovery operation and the previous wiping operation. If step S53 comes to a negative conclusion, these timer recovery processes are completed, and if not after the cap is removed in steps S55 and S57, the operation for removing the difficult-flowing ink liquid described below is carried out in steps S59 to S69.

In the case where there are still such matters on the nozzle array front surface as the ink liquid and paper powder which have not been wiped off by the blade, the liquid components of the ink liquid evaporate and the ink liquid becomes increasingly difficult to flow, and therefore, after a long period of time, the solidified ink liquid and paper powder cannot be removed even in the wiping operation by the blade. In the case where the ink liquid contains dyes and solvents which have the property of becoming increasingly difficult to flow or crystallizing, a phenomenon occurs that the difficult to flow ink liquid is deposited near the nozzle as the evaporation of the liquid components progresses, so that the nozzle is covered by the solidified ink liquid, which may result in failures of ink ejection.

The difficult-flowing ink liquid remaining on the nozzle array front surface and the solidified ink liquid deposited near the nozzle cannot be removed only by the ordinary wiping operation by the blade and the preliminary ejection operation. Before the preliminary ejection operation, even if the ink liquid is heated to the optimum temperature used for the recording operation of the recording head, failures in ink ejection may frequently occur, and therefore, in the prior art devices, in such a case, the difficult-flowing ink liquid remaining near the nozzle was forcibly discharged by the suction operation.

In contrast to the prior art devices described above, the present invention attempts to remove the difficult-to-flow ink liquid efficiently and without consuming too much ink liquid used for the forced ejection. In this embodiment, in the case where a relatively long period of time of 72 hours has not passed since the previous suction operation, the recovery operation is realized by the wiping operation performed in step S61. Before this wiping operation in step S61, the preliminary heating (B) mode operation is performed in step S59 for heating the nozzle of the recording head and its adjacent surface on the nozzle array front surface.

The difficult-flowing ink liquid is heated in the preliminary heating (B) mode operation, and the viscosity of the ink liquid is reduced so that the ink liquid is easily removed by the wiping operation. The solidified ink liquid deposited near the nozzle gradually softens by using the preliminary heating (B) mode and can be easily removed by the wiping operation even if the entire part of the solidified ink liquid is not completely softened. Although almost the entire parts of the difficult-flowing and solidified ink liquid can be removed from the nozzle assembly front surface, there may be a case that the difficult-flowing and solidified ink liquid cannot be removed only by a single wiping operation or a case that the ink liquid which is not completely softened remains on the nozzle assembly front surface and near the nozzle. In order to cope with such cases, in this embodiment, a plurality of sets of operations of the preliminary heating (B) mode and the wiping operations are carried out n times in a repetitive manner controlled by the step S63. Only the wiping operation is allowed to be repeated.

In the wiping operation after the preliminary heating mode, a part of the difficult-flowing ink liquid removed from the nozzle assembly front surface may be refilled into the nozzle, which still results in failure of ink ejection. In this embodiment, additional operations for the preliminary heating (B) mode and the preliminary ejection (C) mode are carried out in steps S65 and S67, again immediately after step S63, followed by step S69 for resetting the 4-hour timer, before returning to the main routine, as shown in Fig. 7.

Since the purpose of the preliminary heating (B) mode is to facilitate wiping and ejecting the difficult-to-flow ink liquid by reducing the viscosity of the ink liquid with its partially evaporated components, the temperature for the preliminary heating (B) mode is set higher than the temperature of the preliminary heating (A) mode or the recording head heating mode in order to ensure stable ejection performance of the recording head.

In this embodiment, whether or not the preliminary heating mode is required before the wiping operation is determined by the period of time during which the recording head is not operated to discharge ink liquid. Using the 4-hour timer which determines the time elapsed since the last preliminary discharging and wiping operations, the preliminary heating mode is executed only when four hours have elapsed since the last preliminary discharging and wiping operations were completed when the power switch is turned on or the recording operation starts. When the information is continuously recorded, the preliminary heating operation is not executed, and therefore the processing time is not wasted when this operation is not necessary. However, it is recognized that the preliminary heating operation is necessary for removing the ink liquid adhering to the nozzle array front surface during the recording operation. is effective, it is allowed that the preliminary heating operation can be carried out immediately after the recording operation before the wiping operation. In this case, since it can be assumed that it will not become more difficult to flow, the temperature for the heating operation in this case can be set lower than the temperature used in the above-mentioned retrieving operations.

In step S51 in Fig. 8, when it is the case that 72 hours or more have passed since the last recovery process was carried out by the suction operation, when the power switch is turned on or before the recording operation is started, the ejection recovery mode is carried out using the timer suction operation in step S73. In this case, before the ejection recovery mode using the timer suction operation, the preliminary heating (B) mode operation and the wiping operation are carried out in step S71 to facilitate the removal of the difficult-to-flow ink liquid. Since this is also an effective way as an additional option to the suction recovery operation to reduce the amount of ink liquid to be discharged by suction, this heating operation can be carried out in the counter recovery operation shown in Fig. 11 and the forced recovery operation shown in Fig. 12. In this embodiment, since adhered substances such as difficult-flowing ink liquid can be effectively removed, the ejection performance of the recording head can be maintained in a good state for a long period of time.

As shown in Fig. 8, after step S73, the 72-hour timer and the 4-hour timer are reset in steps S75 and S77, respectively, and the wiping operation is carried out in step S79 before returning to the main routine shown in Fig. 7.

Another preliminary heating operation may also be performed before the wiping operation in step S79, and after the wiping operation in step S79, the preliminary operations similar to those in steps S65 and S67 may be added.

Fig. 9 shows an embodiment of the processes of the wiping and capping operations in step S7 shown in Fig. 7. A timer for outputting the elapse of a predetermined period of time, e.g., 0.5 hours, since the cap was put on, which is referred to as a 0.5-hour timer, is first set in step S81 and after the wiping operation is carried out in step S83. Finally, the capping operation is carried out in step S85 before returning to the main program.

Fig. 10A shows an example of the processes of the standby operation for waiting for the request to start the recording operation. First, in a step S91, it is checked whether or not the cap is fitted. If the cap is fitted, in a step S93, it is judged whether or not 72 hours have passed since the cap was fitted. If an affirmative decision is made in step S93, the main routine is called again, and subsequently the suction recovery operation is carried out in the discharge recovery mode using the timer suction operation before the recording operation is carried out. If a negative decision is made in step S93, step S95 is reached, in which it is judged whether or not 0.5 hours have passed since the cap was fitted. If a negative decision is made in step S95, the main routine is called. If step S95 is affirmative, the provisional discharge (C) mode is executed after the provisional heating (B) mode operation is performed in steps 897 and 899. Thereafter, the 0.5-hour timer is reset in step 8101 before returning to the main routine.

In the case where step 891 concludes that the cap is off, i.e., open, it is judged in step 8103 whether or not a predetermined period of time, e.g., 5 seconds, has passed since the cap remained open. If step S103 concludes in the affirmative, the wiping and capping operations described with reference to Fig. 9 are carried out in step S105 before returning to the main routine.

Fig. 10B shows another embodiment of the standby program according to the invention shown in Fig. 10A. In Fig. 10B, a step S98 for the idle ejection operation of the ink liquid into the cap is executed instead of the preliminary ejection (B) and (C) modes in steps S97 and S99 in Fig. 10A. This idle ejection operation of the ink liquid into the capping unit 300 is executed while the communication pipe part of the pump unit 500 to the capping unit 300 is open to the atmosphere. By the idle ejection operation into the cap whose interior is communicated with the atmosphere, the inside of the cap can be kept humid enough and the pressure fluctuation in the cap can be reduced, thus preventing the meniscus of the ink liquid in the ink channel from deviating from a right position.

Fig. 11 shows an embodiment of the forced recovery processes which are triggered by actuating the recovery switch 826.

First, in step S111, during suction of the ink liquid, the preliminary ejection (B) mode operation is carried out, and subsequently, after the preliminary heating (B) mode operation in step S113, the wiping operation in step S115 and the preliminary ejection (A) mode operation in step S117 are carried out. The repetition of these operations is allowed to be controlled by step S119.

For example, as described above, before step S111, the preliminary heating (B) mode operation and the wiping operation may be executed. In addition, before step S117, the preliminary heating (A) mode operation may be executed.

Fig. 12 shows an embodiment of the processes of the counter recovery operations.

First, in a step S121, it is judged whether or not a predetermined number of recording documents, e.g., 10 sheets, have been recorded since the previous suction recovery operation was carried out. If an affirmative decision is made in step S121, the suction recovery operation in the discharge recovery mode is carried out using the counting means described above in step S123 before the preliminary heating and wiping operations can be carried out, and in step S125 the timers are reset.

After step S125 or in the case where step S121 is negative, step S127 is executed for the preliminary heating (B) mode operation, and the wiping operation in step S129 and the preliminary ejection (A) mode operation in step S131 are performed before returning to the main routine.

In the processes of Figs. 6 - 12 described above, the heating of the recording head is carried out before the retrieval operations. However, it may be permitted to carry out the heating of the recording head so as not to exert an adverse effect on the retrieval operations while the retrieval operations are being carried out.

In addition, in the above description, the modes and their operating conditions and setting parameters of the timers are a series of embodiments, and therefore these parameters and conditions are set to appropriate values according to the requirements.

(Checking the effect using examples)

The durability and stability of the quality of the recorded images are checked with respect to the above-mentioned ink jet recording apparatus of the first embodiment of the present invention. The following specifications of the parameters and conditions are used to realize this embodiment.

Sheet: Thickness 0.7 mm ± 0.1 mm

Width 12.0 mm ± 0.1 mm

free length 8.0 mm ± 0 1 mm.

Extension length of the sheet when wiping the recording head 5 with respect to the nozzle array front surface 1.5 mm ± 0.5 mm

Blade extension length when cleaning the blade with reference to the cleaner edge part: 4.0 mm ± 015 mm

Carriage movement speed: 200 mm/s ± 30 mm/s (while wiping)

100 mm/s ± 30 mm/s (during cleaning)

Recording head: 400 dpi (dots per inch), 128 nozzles per recording head

Frequency of wiping operation: 1 time per recording of a single A4 size sheet

Frequency of timer recovery operation: 1 time every 74 hours

Frequency of counter recovery operation: 1 time per recording of 10 sheets

Frequency of the operation to remove the difficult-to-flow ink fluid: once every 4 hours

Temperature of the recording head in the recording operation: 38ºC

Temperature of the recording head in preliminary heating (A) mode: between 35ºC and 40ºC

Temperature of the recording head in preliminary heating (B) mode: more than 50ºC

Ambient air parameters: 35ºC (high temperature) 10% (low humidity).

The test was carried out under such a severe condition that the amount of ink liquid ejected and the amount of ink liquid adhering to the nozzle array front surface are large, the air temperature is high and the humidity is low so that the evaporation of the ink liquid is very intense. In the recording operation in which the ink liquid was fully and steadily ejected during the recording operation per each scanning line on the recording medium, i.e., fully printed, and 5000 sheets of A4 size were recorded in 10 days (500 sheets/day) with 12 hours of rest in which the recording operation was stopped, no ink ejection failure such as intermittent and uneven ejection operations could be observed. However, in the case of skipping the preliminary heating (B) mode operation at the start of the recording operation after stopping the recording operation for 12 hours, there was a case where some failures of ink ejection were observed, confirming the effect of the present invention.

(Variation example of the wiping direction and the timer control of the preliminary heating operation)

In this embodiment, the moving direction of the blade 401 in the wiping operation is perpendicular to the arrangement direction of the nozzles. In a variation of this embodiment, in the wiping operation, the blade 401 may be moved in the direction in which the nozzles are arranged on the nozzle array front surface.

The ink channels, called dummy nozzles, from which the ink liquid is not ejected in the recording operation are arranged in the two end sides of the divided line formed by the nozzles arranged in a matrix. This structure is to reduce the spatial dependence of the ink liquid dynamics in the ejection operation, such as the vibration of the ink liquid.

Dummy nozzles also result in different effects when wiping the nozzles in the arrangement direction of the nozzles. When the difficult-to-flow ink liquid adheres to the nozzle arrangement front surface, the difficult-to-flow ink liquid may return to the nozzles in the wiping operation in the above-described embodiment of the present invention. In this modification, only the ink liquid between adjacent nozzles can return to the nozzles, and even in the nozzles on the both end sides of the divided line formed by the arranged nozzles, the difficult-to-flow ink liquid and unwanted adhesives can be intercepted by the dummy nozzles, and therefore the ejection operation is less dependent on the movement of the difficult-to-flow ink liquid on the nozzle arrangement front surface in this modification than in the original embodiment described above. However, even in this modification, the ink liquid in the dummy nozzles may tend to assume a higher viscosity than the ink liquid in the other nozzles, and therefore the difficult-flowing ink liquid may dry up, solidify, and deposit on the nozzle because the ink is replaced only whenever the suction recovery operation is performed.

In this modification, taking into account the increase in viscosity of the ink liquid, the timer II (the 4-hour timer in the generic embodiment) for judging whether the preliminary heating and wiping operations are required or not and the timer I (the 72-hour timer in the generic embodiment) are related to each other. That is, the time period determined by the timer II is changeable to gradually decrease in response to the time period that has passed since the suction recovery operation was performed. For example, the time period determined by the timer II may be set as 4 x 72/(72 - T1), where T1 is the time period counted by the timer I.

(Modification example of temperature control in the preliminary heating operation)

In the above-described generic embodiment, the temperature in the preliminary heating operation is kept constant. The temperature in the preliminary heating operation may be changed in accordance with the period of time during which the recording is stopped and the viscosity of the ink liquid. In this modification, in the preliminary heating operation, the heat energy is transferred to the ink liquid in the ink channel for a predetermined period of time through the electricity-heat conversion elements used for the ejection operation so that the ink liquid cannot boil and the ink liquid cannot be ejected. That is, the preliminary heating operation is carried out by supplying a predetermined repetitive number of pulses having a pulse width smaller than that in the ordinary ejection or recording operation. In determining the number of pulses, which is to be supplied to the electricity-heat conversion element, reference is made to a reference table in which the number of pulses for the preliminary heating (A) mode operation and the number of pulses for the preliminary heating (B) mode operation are set to coincide with each other in a positive relationship to the minimum number of pulses for (A) and (B).

Similar to changing the number of pulses in the preliminary heating operation, various kinds of parameters can be selected as effective choices for removing the difficult-flowing ink liquid after a predetermined period of time since the completion of the recording operation, which include:

- the duration of the preliminary heating (B) mode operation,

- the number of repeated wipes in a single wipe operation,

- the preliminary ejection condition after the wiping operation,

- the combination of suction recovery operation and other recovery operations.

The selection of these alternatives is based on the ambient temperature, the amount of ink liquid held in the ink tank, which may affect the static ink liquid pressure developed at the nozzle, the frequency of recording operations before the recording operation is temporarily stopped, which affects the amount of ink liquid adhering to the nozzle array front surface of the recording head.

SECOND EMBODIMENT:

This embodiment relates to the structure for performing the idle discharge operation into the cap whose interior is communicated with the atmosphere.

Fig. 13 is an overall perspective view of an ink-jet recording apparatus of the second embodiment of the present invention.

In Fig. 13, the component 201 is a base on which the left side mounting plate 201a and the right side mounting plate 201b are fixedly arranged, which are also used as guides for a recording medium such as a paper sheet. A front plate 201c is arranged on the right end part of the base 201, and a carrier guide plate 201d is arranged on the front end part of the base 201. The component 201e is an elongated hole for guiding the carrier formed in the carrier guide plate 201d, and the carrier guide roller described below is connected to the elongated hole 201e so as to be freely movable in the width direction. In addition, a motor mounting hole not shown in Fig. 13 for supporting the support motor described below is formed on the base 201 so that the support motor can move and rotate.

The guide arm 201h formed in a fixture attachment part is used to support a lead screw described below in its axial and radial directions, and its support point is defined on the bearings of the guide arm 201h.

The component 202 is a lead screw on whose surface a guide groove 202a is formed with a predetermined pitch corresponding to the recording width of the recording head on the recording medium. On the side of the carrier home position of the lead screw 202, a capping recess 203b used for setting a capping position and a recovery position is formed as a circle around the cross section perpendicular to the axis of the lead screw 202, and the capping recess 203b and the guide groove 202a are continuously connected by the connecting recess 203c.

At both ends of the lead screw 202, axles 2029 are formed and coupled to the bearings formed on the front plate 201c and the guide arm 201b for free rotation. A pulley 203a is arranged adjacent to the end portion of the lead screw 202, which is supported by the guide arm 201h. The pulley 203a is driven by the motor 211 via the timing belt 213. The axle 2029 on the right side of the lead screw 202 is urged in the axial direction by a plate spring not shown in Fig. 13.

Further, a clutch gear 204 is disposed adjacent to a portion of the lead screw 202 in which the pulley 203a is fixedly disposed. The clutch gear 204 is supported by the lead screw 202 so as to be able to move freely in the axial direction of the lead screw and is coupled to a stopper member not shown in Fig. 13 so that a rotational force developed by the lead screw 202 can be transmitted to the lead screw 202. A component 205 is a clutch spring which is formed as a compression spring so that the clutch gear 204 can be pressed toward the guide groove 202a. A restricting member is formed between the clutch gear 204 and the lead screw 202 to restrict the displacement of the clutch gear 204 within a predetermined range. The restriction element is not shown in Fig. 13.

The component 206 is a carrier which is arranged on the lead screw 202 to move along the lead screw 202. The component 206a is a pressing member which is formed jointly on the left side of the carrier 206 for pressing the front side of the clutch gear 204 in response to the displacement of the carrier 206. The component 206b is a sensing rod formed on the carrier, the position of which with respect to the displacement of the carrier 206 is detected by the sensor described below to detect that the carrier 206 is arranged in the initial position. The component 207 is a guide pin which is arranged in the carrier 206 and connected to the guide groove 202a on the guide screw 202. When the guide screw 202 rotates, the guide pin 207 receives a force developed by the guide groove 202a in the axial direction of the guide screw 202, and therefore the carrier 206 can be moved. The component 208 is a guide pin spring, one end of which is fixedly arranged on the carrier 206, which presses the guide pin 207 toward the guide groove 202a to bring about an effective coupling between the guide pin 207 and the guide groove 202a.

The component IJC is a recording head cartridge which is detachable from the carrier 206. In this embodiment, the recording head cartridge IJC is formed as a single cartridge unit having a recording head unit IJU for ejecting ink liquid and an ink tank IT as an ink liquid source. Due to this structure, the recording head unit IJU and the ink tank IT can be replaced together when the ink tank IT is empty. With respect to the energy generating elements arranged in the recording head unit IJU and used for generating energy in the ink liquid for ejecting ink liquid, an electricity-heat conversion element or an electromechanical conversion element may be used. In the recording head unit of this embodiment, the first-mentioned element is used because this element allows the arrangement of the nozzles for ejecting the ink liquid in high density and enables easier assembly processes.

The component 210 is a carrier roller which is arranged on the rear end surface of the carrier 206 so that it is freely rotatable and is connected to the elongated hole 201e on the carrier guide plate 201d of the base frame 201.

The component 211 is a support motor such as a stepping motor. On the front surface and the rear surface of the support motor 211, pivot pins 211a are arranged at an eccentric position under the axis of the support motor 211, and these pivot pins 211a are coupled to the motor mounting holes formed on the base 201 to rotate freely. Therefore, the support motor 211 can be rotated on the axis of the pivot pins 211a. The component 211b is a spring pawl formed together with the support motor 211 and arranged to be parallel to the axis of the support motor 211 to fix the end of the motor spring 214 described below. A cylindrical protruding portion is formed on the spring pawl 211b to firmly locate the end of the motor spring 214.

The component 212 is a motor pulley fixedly arranged on the axis of the carrier motor 211. The component 213 is a timing belt extending between the motor pulley 212 and the pulley 203a fixedly arranged on the axis of the lead screw 202. The motor spring 214 of this embodiment is a spiral compression spring arranged between one end of the guide arm 201h and the spring pawl 211b of the carrier motor 211. With this structure, the timing belt 213 can be stretched in the direction indicated by an arrow A in Fig. 13 by the rotational displacement of the carrier motor 211 on the pivot pins 211a.

A setting shaft 215 is arranged on the left side plate 201a, and a blade for cleaning the nozzle array front surface of the recording head unit, a cap and other mechanisms for the ejection recovery operations are arranged around the setting shaft 215.

The projection part of the blade lever 216 for moving the blade for wiping the nozzle array front surface with respect to the recording head is arranged on the setting shaft 215 so as to be freely rotatable.

In addition, a setting lever 220 is arranged on the setting shaft 215 so as to be freely rotatable, and the setting lever 220 rotates in response to the rotation of the lead screw 202 which is connected to the clutch gear 204 and driven by the carrier motor 211. When the lead screw 202 rotates, the hook formed on the upper part of the setting lever 220 is connected to a bolt not shown in Fig. 13 of the blade lever 216, and a protruding part of the setting lever 220 is connected to an elongated hole not shown in Fig. 13 which is formed in the blade lever 216. By this structure, the blade lever 216 rotates with delay in response to the rotational movement of the set lever 220, and therefore the wiping action of the blade 217 not shown in Fig. 13 is effected so that the nozzle array front surface of the recording head unit IJU can be cleaned.

In the opposite position to the home position of the recording head unit IJU of the recording apparatus, the cap 235 is arranged. The cap 235 can also move forward and backward with respect to the nozzle array front surface of the recording head unit IJU in response to the rotation of the lead screw 202 caused by the force transmitted from the clutch gear 204. A recovery system unit having the cap 235 will be described below with reference to Fig. 14A, Fig. 14B and Fig. 15.

The component 224 is a cylinder composed of a hollow cylinder part 224a and a guide part 224b for guiding the piston rod described below. In the guide part 224b, an ink channel is created by removing a part of the cylindrical member in the axial direction. The component 224d is a cap lever pawl which is designed so that a lever seal described below can be held by the cap lever pawl. The component 224e is an ink channel which is provided with an open passage in a predetermined position. within the cylinder part 224a. The component 224f is a rotary lever which is formed together with the cylinder 224 and to which a rotary force is applied by the cap spring 243 not shown in Fig. 14A. The component 224g is a waste ink pipe which is formed together with the cylinder 224 and whose upper part is shaped so that the waste ink pipe can be easily inserted into the waste ink absorber 237 described below. The component 224h is an ink channel which is formed in the waste ink pipe 224g.

The component 225 is a cylinder cap which is pressed against the end part of the cylinder 224. The component 225a is a lever guide arranged in the opposite position to the above-mentioned cap lever pawl 224d of the cylinder 224.

The structural member 226 is a piston seal inserted into the cylinder 224, and its inner diameter is selected to be slightly smaller than the diameter of the piston rod so as to exert a predetermined pressing force on the piston rod. The friction between the piston seal and the piston rod is allowed to be reduced by applying a lubricating fluid to the surface of the piston seal.

The component 227 is a piston rod around which an action rod 227a, a piston rod support 227b, a piston pawl 227c, a connecting rod 227d and a guide rod 227e are arranged, and in addition, a recess 227f used as an ink channel is formed along the connecting rod 227d and the guide rod 227e. The component 227f is a rotation stopper member defined as a recess formed on the action rod 227a. The piston rod support 227b is formed on the end surface of the action rod 227a.

The component 228 is a piston made of rubber materials such as NBR, and the details of the structure are shown in Fig. 14B.

In Fig. 14B, the member 228c is a sealing rib which is annular, whose axis coincides with the axis of the end face part 228b of the piston 228, and whose end face is located on the same surface defined by the end face part 228b. The sealing rib 228 directly contacts the piston rod support 227b when the piston 228 moves and connects with the piston rod support 227b, and the close contact between the sealing rib 228c and the piston rod support 227b can be brought about by forming a contact part as a circular line, and when the piston 228 moves back from the piston rod support 227b, the difficult-to-flow ink liquid does not adversely affect its separation movement. The piston 228 can be made of ink-absorbing materials, such as polyurethane foam, which have air-filled cavities. In this case of using polyurethane foam with a property of retaining moisture, it is advantageous that the frictional properties between the cylinder 224 and the piston 228 do not change even if the piston deforms due to low humidity after a period of time in which the pump has not been operated.

As shown in Fig. 14A, Fig. 14B and Fig. 15, the component 224 is a pump chamber whose suction pressure develops in response to the displacement of the piston 228. The component 229 is a piston pressing roller which is arranged at the end part of the piston rod 227 so as to be able to rotate freely. The component 230 is a piston recovery roller which is also arranged at the end part of the piston rod 227 so as to be able to rotate freely. The component 231 is a common axis of these rollers 229 and 230. The piston pressing roller 229 and the piston recovery roller 230 are connected to a cam body not shown in Fig. 14A, and this cam body is rotated by the rotational movement the lead screw 202 which is transmitted through the clutch gear 204, etc. Due to this structure, the piston 228 can reciprocally move inside the cylinder 224 to perform ink liquid suction operations.

The component 232 is a cap lever around which a rotary shaft 232a, an ink guide 232b and a lever guide 232c are formed together. A convex and a spherical sealing surface 232d are formed on the top of the cap lever 232. A pair of coupling parts 232e are formed on the top of the cap lever 232, to which latches of the cap holders described below are coupled. Further, an ink channel 232f passes from the sealing surface 232d through the cap lever 232, turns at right angles in the middle of the ink guide 232b and finally reaches the open passage formed on the ink guide 232b along the central axis of the ink guide 232b. A cutout portion 232g is formed on the bottom of the ink guide 232b.

The component 233 is a lever seal into which the ink guide 232b is inserted and which is inserted into the cap lever pawl 224d. The component 233a is an air passage hole between the cutout portion 232g of the ink guide 232b and the ink passage 224e.

The component 234 is a cap holder, and two pairs of hooks 234a, which are connected to the coupling part 232e of the cap lever 232, are formed at the corners of the cap holder 234. The component 234b is an open passage, at which a cap described below is arranged.

The component 235 is a cap which is placed on the open passage 234b of the cap holder 234. The cap 234 is used to cover the nozzle array front surface of the recording head unit IJU to prevent the ink liquid from evaporating and to provide a to apply suction pressure inside the cap to suck the ink liquid. A suction port 235a is formed on the cap 235, and the ink channel formed by the cap 235 extends from the suction port 235a to the open passage on the opposite side, winding between these ports. This open passage on the opposite side of the cap 235 is connected to the open passage formed on the sealing surface 232d and further connected to the ink channel 232f in the cap holder 234.

The component 235b is a flange part formed in a part of the cap 235 and used for fixedly arranging the cap 235 in the cap holder 234. A cap sealing part 235c not shown in Fig. 14B is formed on the flange part 235b, the shape of which is a concave ball whose curvature is equal to the curvature of the sealing surface 232d of the cap lever 232. When the cap 235 is arranged in the cap holder 234, the cap 235 is pressed against the cap lever 232, and the communication between the open passages of the cap 235 and the cap lever 232 is established, thus forming the continuous ink channel. In this structure, since the shape of the sealing parts 232d and 235c is a sphere, the compensating ability of these cap members is high even if there is some off-center displacement between the cap 235 and the cap lever 232, and therefore a reliable sealing state can be ensured by correcting the uneven and intermittent displacement on the nozzle assembly front surface.

Fig. 15 shows a case where the piston 228 is located at a top dead center. In the capping operations for the nozzle array front surface of the recording head unit IJU, the piston 228 is located at a top dead center. In this state, since the ink channel 224e formed in the cylinder 224 is not closed by the rib 228d of the piston 228 and the end part of the waste ink line 224g is discharged via the absorber 237 which contains air-filled cavities, the interior of the cap 235 is in an intermediate opening state to the atmosphere via the ink channel 232f as shown in Fig. 14A, Fig. 14B and Fig. 15. Accordingly, there is no such problem in capping the recording head as conventionally known as one of the problems such as leakage of the ink due to the pressure change in the cap.

In Fig. 13, the component 236 is a paper feed roller for feeding the recording medium such as sheet paper, which is produced, for example, by coating an aluminum hollow cylinder with elastic materials such as polyurethane foam. Not only the paper feed roller 236 is used as a paper transport roller for flattening the recording surface of the recording medium on the surface thereof, but also the inside of the paper feed roller 236 is used as a reservoir for the waste ink liquid. The component 237 is a waste ink liquid absorber which is arranged in the paper feed roller 236 and comprises a plurality of thin tubes made of plastic material such as polyethylene and EVA, each tube being filled with absorbent material such as polyethylene and EVA. B. Polyester textiles, so that the entire body forms the waste ink liquid absorber 237. Fibrous materials are preferable for the waste ink liquid absorber over such non-absorbent materials, e.g. B. synthetic resins and metals.

The component 238 is a paper pressure plate arranged on the base frame 201. The component 239 is a paper feed motor which is connected to the paper feed roller 236 via reduction gears with a predetermined reduction ratio.

Component 240 is a recording medium such as sheet paper and transparent film.

The component 241 is a detection device for detecting the home position of the carrier, which in this embodiment is constructed of a photo interrupter that uses optical signal processing. In the detection device 241, the sensor element of the carrier 206 can judge whether the carrier is arranged in the home position or not when the optical beam to the optical detection device is interrupted.

Fig. 16 is a block diagram showing an embodiment of the process configuration of the control system in the ink jet recording apparatus shown in Fig. 13.

The device 800 is a controller which forms a main control part with the CPU 801 such as a microcomputer which executes the processes shown in Fig. 17A and Fig. 17B, a ROM 803 which has the programs of the processes, a table which has voltage data of the drive signal, the pulse width and other fixed data used for generating the drive signals for driving the electricity-heat conversion element of the recording head unit, and a RAM 805 which has an area for storing the image data and an area for temporarily storing the working data. In addition, the controller 800 has a timer for counting the predetermined time period as described with reference to Fig. 17A and Fig. 17B. The device 810 is a host system as an output device for image data, which exchanges image data, control commands and status signals with the control device 800 via the interface (I/F) 812.

The component 820 is a switch set for inputting commands and requests by the operator, which includes a power switch 822 for turning on and off the recording operations realized by the software of the ink jet recording device, and a general recovery operation switch 826 for requesting initiation of the general recovery operation as one of the recording and ejection recovery processes. The device 830 is a sensor set for detecting the device state, which includes sensors for detecting the home position and the start position of the carriage 206, etc.

The device 840 is a recording head driver for driving the electricity-heat conversion element of the recording head unit in response to the recording data. A part of the recording head unit is responsive to the recording data. A part of the recording head driver is used for driving the temperature control heaters 30A and 30B. In addition, the temperature detection signals from the temperature sensors 20A and 20B are supplied to the controller 800. The device 850 is a main scanning motor for moving the carriage 882 in the direction in which the paper transport roller extends, and the device 852 is a driver for the main scanning motor 850. The device 860 is a sub-scanning motor used for transporting the recording medium.

Fig. 17A and Fig. 17B show flowcharts of the processes related to the request via a switch of the ink-jet recording apparatus described above.

In the recording device of this embodiment, the CPU 801 of the controller 800 shown in Fig. 16 is ready to operate when the power cord is connected to the power input jack. In this state of the recording device, the information display devices of the recording device of this embodiment are not activated, and the recording device does not accept the request command for initiating the recording operation and the recording data, but the CPU 801 of the recording device is activated to execute the processes described below.

In step S201, it is checked whether or not the data transferred from the host system 810 is stored in the RAM shown in Fig. 8. If the recording data is present in the recording device, it is checked in step S202 whether or not the power switch 822 shown in Fig. 16 is turned on. If the power switch 822 is turned on, the recording operation and the transmission start, and the signal exchange with the host system can be permitted. In addition, the above-described information display means of the recording device of this embodiment are activated. If the power switch 822 is turned off, the recording operation is not carried out, and if the power switch 822 is turned on, the recording operation is carried out and the capping operation is checked in step S203.

If step S203 determines that the cap is fitted and the recording operation is ready to be performed, it is checked in step S204 whether the recording head has not been used for the ejection operation for a predetermined long period of time. In this embodiment, if the recording head has not been used for more than 72 hours, step S204 concludes that the recording head has not been used. If so, step S205 is then selected to perform the suction operation by operating the plunger 228 shown in Fig. 14A and Fig. 14B. Thereafter, in step S206, the timer for counting the 72 hours, which is referred to as a 72-hour timer, is reset for restart. Subsequently, in step S207, the 30-minute timer for judging the idle ejection operation is reset in the cap for restart. This is because the recording head is driven when the suction operation is performed. If step S204 concludes that the recording head has not been used for more than 72 hours, then step S208 is directly selected after step S204.

In step S208, the cap 235 is opened, and then in step S209, the nozzle assembly front surface is wiped of the recording head, and further in step S210, the idle ejection operation is carried out before the recording operation in step S211.

While the recording operation is continuing, steps S201 to S211 are repeated until step S203 judges that the cap is open, and further step S212 is selected. In step S212, it is judged whether the recording operation has been continuously carried out for more than 12 seconds, and if step S212 concludes that this is so, the idle ejection operation is carried out during the recording operation in step S213. This idle ejection operation in step S213 is for removing the difficult-flowing ink liquid in the nozzles from which the ink liquid has almost not been ejected for a long period of time, as opposed to the nozzles from which the ink liquid has almost always been ejected. After the idle ejection operation in step S213, the 12-second timer for restart is reset in step S214. Thereafter, it is judged in step S215 whether or not the recording operation has been continuously continued for more than 60 seconds. If the recording operation has been continuously carried out for more than 60 seconds, the wiping operation is carried out in step S216. By this wiping operation, further ink droplets and dust adhering to the nozzle array front surface of the recording head due to the ink liquid mist or the like during the recording operation can be removed, so as to prevent these undesirable matters on the recording head from causing ejection direction errors, etc.

If it is judged in step S201 that the recording data does not arrive in the recording device, ie the recording device is ready to start the recording operation, step S218 is then carried out without considering whether the power switch 822 is on or off. In step S218, it is judged by the 72-hour timer whether the recording head is ready for has not been used for a long period of time. If step S218 concludes that the recording head has been used for the past 72 hours, it is checked in step S219 whether or not the capping operation has been carried out. In step S220, it is judged by the 30-minute timer whether or not 30 minutes have passed since the last idle ejection operation. If 30 minutes have passed, the idle ejection operation into the cap is carried out in step S221. This process is based on the present invention. That is, by capping the nozzle of the recording head and appropriately determining the position of the piston of the suction pump which communicates with the atmosphere, the ink liquid can be discharged in the state where the suction path defined in the suction pump is released to the atmosphere. By this structure, the closed space formed by the cap and the recording head can be kept humid enough, and since this space is connected to the atmosphere, the pressure change in this space can be avoided, so that a predetermined position of the meniscus of the ink liquid inside the recording head is properly established.

Accordingly, it is advantageous that an ordinary ejection operation of the ink liquid can be carried out without preparing the recovery processes before the recording operations by preventing the ink liquid from solidifying due to evaporation of the solvent component of the ink liquid, by discharging the almost hard-flowing ink liquid from the inside of the nozzle, and by maintaining the humidity inside the cap with the ink liquid discharged into the cap.

When the ink liquid is ejected into the cap, the excess amount of ink liquid or the ink liquid remaining inside the cap after the last ejection operation can be moved to the suction pump to maintain the pressure balance. This mechanism advantageously achieves that the inside of the cap can be kept moist and that the solidification of the ink liquid within the ejection recovery system as well as the ink liquid within the recording head is prevented.

Thereafter, in step S222, the 30-minute timer for restart is reset. If step S218 concludes that more than 72 hours have passed, it is judged that the recovery operation is executable only by the idle ejection operation into the cap after such a long period of time has passed without ejecting the ink liquid from the recording head. In this case, steps S119 to S222 are skipped. This means that the ejection recovery operation is more effective than the ejection charging recovery operation, and that an ineffective ejection operation only wastes the ink liquid.

THIRD EMBODIMENT

In this embodiment, in addition to the structure of the second embodiment described above, an air temperature sensor for measuring the temperature of the atmospheric air or a recording head temperature sensor and a humidity sensor for measuring the humidity of the atmospheric air are used. With this structure, the number of repetitions of the idle ejection operations into the cap and the operating conditions can be optimized. The number of repetitions of the idle ejection operations per second is determined from, for example, the table shown below. TABLE 1

Since the ink liquid becomes increasingly difficult to flow and dries up as the temperature and humidity are lower, the electricity-heat conversion element (ejection heater) is driven by pulses of smaller pulse width so that the bubbles cannot occur in the ink liquid, and after the ink liquid near the nozzle is only heated to reduce the viscosity of the ink liquid, the idle ejection operation into the cap is carried out. In the case that the temperature is low and the humidity is high, the ink liquid near the nozzle is only heated, and the number of idle ejection operations into the cap is reduced or the period of the pulse is set to be longer. Further, in the case that the temperature is high and the humidity is low, the number of idle ejection operations into the cap is increased or the period of the pulse is set to be shorter. As such, the optimum conditions for the idle ejection operations into the cap can be set taking into account the changes in the state of the surrounding air. It is recognized as advantageous that the number of idle ejection operations can be reduced and the amount of wasted ink can be reduced in the case of relatively good ambient conditions.

It is considered to be advantageous that the reliability of the recovery operations can be increased by using the predetermined ejection patterns for the number of idle ejection operations. For example, by increasing the number of ejection repetitions to be 10 times as many as other repetitive ejection operations every five cycles of the idle ejection operations into the cap. It is considered to be advantageous that the ink liquid near the nozzle can be almost completely replaced and the undesirable substances adhering around the nozzle on the nozzle array front surface can be completely removed.

The present invention achieves a marked effect when applied to a recording head or a recording device having means for generating heat energy such as electricity-heat conversion elements or laser light, which causes changes in the ink by the heat energy to thereby discharge the ink. This is because such a system can achieve high density and high resolution recording.

A typical structure and the working principle are described in U.S. Patent Nos. 4,723,129 and 4,740,796, and it is preferable to apply this basic principle in realizing such a system. Although this system is applicable to either an on-demand type or a continuous type of ink jet recording system, it is particularly suitable for the on-demand type apparatus. This is due to the fact that the on-demand type apparatus comprises electro-thermal conversion means each of which is arranged on a substrate or in a liquid channel which holds the liquid (ink) and operates as follows: (1) one or more drive signals are applied to the electro-thermal conversion means to generate heat energy in accordance with the recording information, (2) the heat energy causes the sudden temperature rise exceeding the core boiling to cause the film boiling on the heating portions of the recording head, and (3) bubbles grow in the liquid (ink) in accordance with the drive signals. Utilizing the growth and collapse of the bubbles, the ink is ejected from at least one of the ink ejection nozzles of the recording head to form one or more ink drops. The driving signal in the form of a pulse is preferable because the growth and collapse of the bubbles can be achieved instantaneously and is suitable for this form of driving signal. As a driving signal in the form of a pulse, those in the US patents No. 4,463,359 and No. 4,345,262. In addition, it is preferable that the rate of temperature rise of the heating sections described in U.S. Patent No. 4,313,124 is adopted to achieve better recording.

U.S. Patent Nos. 4,558,333 and 4,459,600 describe the following structure of a recording head used in the present invention: this structure has heating sections arranged in curved sections in addition to a combination of the ejection nozzles, liquid passages and the electricity-heat converting means described in the above-mentioned patents.

Furthermore, the present invention can be applied to structures as described in Japanese Laid-Open Patent Applications No. 123670/1984 and No. 138461/1984 to achieve similar effects. The former describes a structure in which a slit common to all the electricity-heat conversion devices is used as the discharge nozzle of the electricity-heat conversion devices, and the latter Japanese Laid-Open Patent Application describes a structure in which openings for absorbing the pressure waves caused by the heat energy are formed corresponding to the discharge nozzles. Thus, regardless of the type of the recording head, the present invention can achieve recording in an advantageous and effective manner.

The present invention is also applicable to a so-called full-line recording head whose length is equal to the maximum length across a recording medium. Such a recording head may comprise a plurality of recording heads combined with each other or one recording head arranged integrally.

In addition, the present invention is applicable to various series recording heads:

- on a recording head which is fixedly arranged on the main assembly of a recording device,

- to an easily replaceable chip type of the recording head, which when arranged on the main assembly of a recording device is electrically connected to the main assembly and is supplied with ink by the main assembly, and

- to a cassette type of recording head, which has an ink tank as a single piece.

It is further preferable to add a recovery system or a preliminary auxiliary system for a recording head as a constituent part of the recording apparatus because they serve to make the effect of the present invention permanent. As examples of the recovery system, there are mentioned a capping means and a cleaning means for the recording head, and a pressing or sucking means for the recording head. Examples of the preliminary auxiliary system are a preliminary heating means using electricity-heat converting means, and a means for carrying out preliminary ejection of the ink independently of the ejection for recording.

The number and type of recording heads to be arranged in a recording device can also be changed. For example, only one recording head corresponding to one color ink or a plurality of recording heads corresponding to a plurality of inks of different colors or concentrations may be used. In other words, the present invention is effectively applicable to a device having at least one of monochromatic mode, multicolor mode and full-color mode. Here, in the monochromatic mode, recording is carried out by using only one main color such as black. The multicolor mode carries out recording by using various color inks, and the full-color mode carries out recording by color mixing.

Although the above-described embodiments use liquid ink, inks which are liquid when the recording signal is applied are also usable: for example, inks which solidify at a temperature lower than room temperature and which are softened or liquefied at room temperature can be used. This is because in the ink jet system, the temperature of the ink is substantially controlled in a range of 30°C - 70°C so that the viscosity of the ink is maintained at such a value that the ink can be reliably ejected.

Furthermore, the present invention can be applied to such an apparatus in which the ink is liquefied by the heat energy just before ejection, as a result of which the ink is ejected from the nozzles in a liquid state and then begins to solidify upon impact with the recording medium, preventing the evaporation of the ink: the ink is converted from the solid state to the liquid state by selectively applying heat energy which would otherwise cause the temperature to rise. In such cases, the ink may be held in a liquid or solid state in recesses or through holes formed in a porous substrate so that the ink is in the position opposite to the electricity-heat conversion devices, as described in Japanese Patent Laid-Open No. 56847/1979 or No. 71260/1985. The present invention is most effective when it uses the film boiling phenomenon to eject the ink.

Furthermore, the ink jet recording apparatus of the present invention can be used not only as an image output terminal of an information processing apparatus such as a computer, but also as an output device of a copying machine having a reading device, as an output device of a A facsimile apparatus having a transmission and reception function and as an output device of an optical disk device or an optical storage disk device for recording and/or reproducing the information on and/or from an optical disk or an optical storage disk device. This apparatus requires a means for outputting the processed information in the form of the hard copy.

Fig. 18 schematically shows an embodiment of a use device to which the ink jet recording device shown in Fig. 2 and Fig. 13 can be connected as an output device for outputting the processed information.

In Fig. 18, reference numeral 10000 schematically indicates a utility device, which may be a work station, a personal or host computer, a word processor, a copying machine, a facsimile machine, or an optical disk or storage disk device. Reference numeral 11000 indicates the ink jet recording device (IJRA) shown in Fig. 2 and Fig. 13. The ink jet recording device (IJRA) receives the processed information from the utility device 10000 and makes a hard copy print output under the control of the utility device 10000.

Fig. 19 schematically shows another embodiment of a portable printer according to the present invention, to which a user device such as a work station, a personal or host computer, a word processor, a copier, a facsimile machine, or an optical disk or storage disk device can be connected.

In Fig. 19, reference numeral 10001 schematically designates such a device for use. Reference numeral 12000 schematically designates a portable printer which uses the ink jet recording device shown in Fig. 7. (IJRA), interface switching devices 13000 and 14000 which receive the information processed by the utilization device 11001, and various control data for controlling the ink jet recording device 11000, including handshake and interrupt control from the utilization device 11001. Such control is realized per se by the conventional printer control technology.

Claims (16)

1. Inkjet recording system or inkjet recording device comprising: - an inkjet head with a nozzle (12) for ejecting ink, - a cleaning element (401) for cleaning the front surface (1) of the inkjet head in which the nozzle is arranged, - a heating device (86, 870) for heating the inkjet head and - a recovery control device (800) adapted to carry out a recovery operation in which the front surface is heated by the heating device to such a degree that the viscosity of the ink liquid is, however, reduced such that the ink is not ejected and the front surface is cleaned by the cleaning member (401) when the viscosity of the ink is thus reduced. 2. An ink jet recording apparatus according to claim 1, further comprising means for maintaining the ink jet head at a predetermined temperature for the duration of a recording operation, and wherein the temperature of the ink jet head heated by the heating means for the recovery operation is higher than the predetermined temperature. 3. An ink jet recording apparatus according to claim 1 or claim 2, further comprising a cap member (300) for covering said end face (1), having an opening member through which the interior of said cap member is exposed to the atmosphere and wherein the recovery control means is adapted to perform a second recovery operation in which ink liquid is ejected into the cap member when the end face is covered by the cap member but when the cap member is open to the atmosphere. 4. An ink jet recording apparatus according to claim 3, wherein the heating device heats the ink jet head during both recovery operations 5. An ink jet recording apparatus according to claim 3 or claim 4, wherein the recovery control means is adapted to perform both recovery operations repeatedly or to perform the second recovery operation alone repeatedly. 6. An ink jet recording apparatus according to claim 3 or claim 4, wherein the retrieval control means is adapted to perform the retrieval operations repeatedly and at different times or to perform the second retrieval operation alone repeatedly. 7. An ink jet recording apparatus according to any preceding claim, wherein the heating means comprises a heating element for generating heat to eject ink from the nozzle, and the recovery control means causes the heating element to heat the ink during the recovery operation, but not sufficiently to cause the ejection of the ink. 8. An ink jet recording apparatus according to any one of claims 1 to 6, wherein the heating means comprises a heater arranged in the ink jet head and a separate heater for generating heat energy for causing the ejection of ink. 9. Ink jet recording apparatus according to one of claims 1 to 6, wherein the heating device comprises a heating device which is arranged in the ink jet recording apparatus, and a separate heating device is arranged in the ink jet head for generating heat energy to cause the ejection of ink. 10. A recovery method for performing a recovery operation in an ink jet recording apparatus, which has an ink jet head with a front surface (1) with a discharge nozzle (12) for discharging ink, the method comprising the steps of: - using a heating device (86, 870) to heat the ink to such an extent that the viscosity of the ink is reduced such that the ink is not ejected, and - cleaning the front surface with a cleaning element (401), whereby the ink is removed therefrom while the viscosity of the ink has been reduced by the heating step. 11. A recovery method according to claim 10, which comprises using a heater disposed in the ink jet head as a heating means for generating heat for causing ink ejection. 12. A recovery method according to claim 10 or claim 11, wherein the ink jet head is maintained at a predetermined temperature for a recording operation, and the temperature of the ink jet head when heated for the recovery operation is higher than the predetermined temperature. 13. A recovery method according to claim 12, wherein a second recovery operation is carried out by sucking ink from the ejection nozzle, and a predetermined period of time after the second recovery operation, either the cleaning step or an idle ejection operation is carried out. 14. The recovery method according to claim 13, wherein the cleaning step is carried out during the recording operation. 15. A recovery method according to claim 14, wherein the idle ejection operation is carried out while the recording operation is in the standby state. 16. A recovery method according to claim 15, wherein the second recovery operation in which the suction of ink from the nozzle is carried out is carried out again when the time period since the second recovery operation which was last carried out exceeds a predetermined value without any other recording or recovery operation being carried out.