JP2757225B2 - Recovery method for inkjet recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recovery method for an ink jet recording apparatus that performs recording by discharging ink from a recording head onto a recording material.

[Conventional technology]

2. Description of the Related Art Recording devices such as printers, copiers, and facsimile machines are configured to form an image composed of a dot pattern on a recording material such as paper or a thin plastic plate based on recording information.

The recording device can be classified into an ink jet type, a wire dot type, a thermal type, a laser beam type, and the like according to a recording method. , Also referred to as ink).
The recording is performed by attaching this to a recording material such as a sheet of paper or a plastic thin plate.

One configuration example of a conventional ink jet recording apparatus is disclosed in Japanese Patent Application Laid-Open No. 60-247564 by the same applicant.

This ink jet recording apparatus has an opening / closing means (valve, etc.) in the middle of an ink supply path connecting the recording head and the ink tank.
And a pump, and by appropriately switching the open / close state of the opening / closing means and the operating state of the pump, clogging of the liquid path (liquid flow path leading to the discharge port) of the recording head in addition to the recording mode for performing recording. It is configured to be able to set a pressurizing mode for performing a removing process, a circulation mode for performing a removing process for bubbles in the ink supply path, and the like.

FIG. 8 is a block diagram schematically showing a configuration of an ink supply system of such an ink jet recording apparatus.

In FIG. 8, the ink supply system includes a recording mode,
The operation of the on-off valve 150, the on-off valve 152 for ventilation, the on-off valve 154, and the pump 156 is controlled in accordance with the operation mode such as the circulation mode and the pressurization mode, so that the first ink tank 130 and the second ink tank 140 An appropriate ink flow path is formed between the recording head 174 (a plurality of recording heads in the illustrated example).

The operation of each on-off valve and pump in each of the operation modes is as shown in Table 1.

FIG. 9 is a cross-sectional view schematically showing a state in which the operation of the circulation mode or the pressurizing mode is performed to cause the ink to flow in the recording head 174 in FIG.

In FIG. 9, a plurality of liquid paths 21 communicating with the common liquid chamber 28 are formed inside the recording head 174, as shown in FIG.
A plurality of ejection ports 24 are formed on the ejection port surface (front surface) 27 of the recording head 174 by opening each liquid path 21 as a fine opening. Reference numeral 25 denotes small bubbles (small bubbles) generated in the liquid path 21.

[Technical problem to be solved by the invention]

However, in the above-mentioned conventional ink jet recording apparatus, even if the ink 22 in the recording head 174 is caused to flow in the direction of the arrow 23 in order to remove the small bubbles 25 remaining in the liquid path 21, In some cases, the liquid bubbles 21 pass through in the direction of the arrow 26 and do not reach the point where the small bubbles 25 are pushed out from the discharge port 24. For this reason, the small bubbles sometimes caused non-ejection.

The present invention has been made in view of such a conventional technical problem, and even when small bubbles are generated in a liquid path of a recording head, the small bubbles can be reliably removed, and a stable ink is always obtained. An object of the present invention is to provide a method for recovering an ink jet recording apparatus capable of performing ejection.

[Means for solving the problem]

The present invention provides a recording head that is provided with a thermal energy generating unit that generates thermal energy used to discharge ink, and that performs recording by discharging ink under driving conditions during recording, Fluid means for circulating and flowing, and a recovery method for an ink jet recording apparatus, comprising: flowing the ink in the recording head by operating the fluid means,
By driving the thermal energy generating means under a driving condition different from the driving condition at the time of recording to eject ink from the recording head, even if small bubbles are generated in the liquid path of the recording head, The present invention provides a method for recovering an ink jet recording apparatus that can surely remove the ink droplets and always perform stable ink ejection.

〔Example〕

 Hereinafter, the present invention will be specifically described with reference to the drawings.

FIG. 2 is a schematic side view showing one configuration example of an ink jet recording apparatus suitable for carrying out the recovery method according to the present invention.

In FIG. 2, reference numerals 1 Bk, 1 y, 1 m, and 1 c denote recording heads (for example, a bubble jet type ink jet head) corresponding to black, yellow, magenta, and cyan ink colors, respectively. Ink droplets (recording droplets) are ejected from ejection ports by using bubbles generated in the ink when current is supplied to a heating resistor or the like as a pressure source.

That is, these recording heads 1 Bk, 1y, 1m, 1c are:
By thermal energy, droplets are ejected from the ejection port and fly,
This is attached to a recording material such as a sheet of paper or a plastic thin plate to record.

These recording heads 1 Bk, 1 y, 1 m, and 1 c are fixed to the block 2. Each recording head 1 has, for example, 400 dpi
4736 discharge ports are arranged at a density of.

Reference numeral 3 denotes a capping unit which moves to the position shown in FIG. 1 when the block 2 is raised to a position shown by a dashed line in FIG.
Is used for capping (sealing) the discharge port surface. Further, the capping unit 3 has a receiving tray for receiving a portion (waste ink) of ink circulated from the recovery pump and the ink supply system into the print head 1 from the discharge port at the time of circulation recovery. Become. The received waste ink is guided to a waste ink tank (not shown).

Reference numeral 4 denotes an endless charging / adsorbing belt which is disposed so as to face the recording heads 1 Bk, 1y, 1m, and 1c at predetermined intervals, and conveys a recording material 7 such as a recording sheet or a thin plastic plate. , 5 are recording heads 1 Bk, 1y, 1
This is a back platen that supports the charging and attracting belt 4 from the back in the areas m and 1c.

Reference numeral 6 denotes a paper feed cassette in which the recording material 7 is stored and detachably attached to the apparatus main body. Reference numeral 8 denotes a pickup roller that feeds out and feeds only one recording material 7 on the uppermost surface.

Reference numeral 9 denotes a transport roller for transporting the recording material 7 sent from the pickup roller 8 to a transport path 10;
Is a transport roller disposed on the exit side of the transport path 10.

Reference numerals 13 and 14 denote heaters and fans for drying and fixing the ink liquid adhered to the recording material 7 by hot air by recording. Reference numeral 15 denotes a discharge roller for discharging the recording material 7 after the fixing is completed to the outside of the apparatus. Reference numeral 16 denotes a tray for sequentially storing the discharged recording materials 7.

Next, the operation of the ink jet recording apparatus having the above configuration will be described.

 First, the recording operation will be described.

When a recording start operation is performed, a recording material 7 of a designated size is sent out of the paper feed cassette 6 by the pickup roller 8. The sent recording material 7 is
The belt is run in a charged state by the transport rollers 9 and 11, and is placed on the charged adsorption belt 4 maintained in a planar shape by the back platen 5.

In conjunction with the leading end of the recording material 7 reaching the lower part of each of the recording heads 1Bk, 1y, 1m, and 1c, the thermal energy generator of each recording head is converted into image data via a head drive circuit. Drive based on By this driving, ink droplets corresponding to the image information are ejected from the ejection ports onto the recording surface of the recording material 7, and adhere to the recording surface to perform recording.

If the recording material 7 has poor (low) hygroscopicity, the adhered ink liquid is rubbed without drying, causing image stains. Therefore, forced drying is performed by the heater 13 and the fan 14 for fixing. The recording material 7 that has been fixed is discharged to a tray 16 by a discharge roller 15.

As described above, each of the recording heads 1 Bk, 1y, corresponding to each ink color of cyan, magenta, yellow, and black,
By providing recording signals corresponding to 1m and 1c, a color image is recorded.

Next, the principle of ejection of the recording head 1 used in the ink jet recording apparatus of FIG. 2 will be described.

In general, a recording head (inkjet) of an inkjet recording apparatus has fine discharge ports formed on a discharge port surface (front surface) facing the recording material 7, a liquid flow path communicating with each discharge port, and a liquid flow path. There is provided an energy action part provided in a part of the road, and an energy generation means for forming and ejecting a droplet by acting on a liquid (ink) in contact with the action part.

Examples of the energy generating means for generating such energy include a recording method using an electromechanical transducer such as a piezo element, irradiating an electromagnetic wave such as a laser to absorb the liquid there, and generating a liquid by a heating action at that time. There is a recording method using an energy generating means for discharging and flying a droplet, or a recording method using an energy generating means for discharging a liquid by heating a liquid with an electrothermal converter.

Among them, a recording head used in an ink jet recording apparatus that ejects liquid by thermal energy can arrange ejection openings for ejecting recording droplets to form flying droplets at a high density, thereby achieving high resolution. Can be recorded.

Further, the recording head using the electrothermal transducer as the energy generating means can be easily made compact as a whole,
In addition, it is possible to make full use of the advantages of IC technology and micro-machining technology, which have been making remarkable advances in technology in the field of semiconductors, and that it is easy to make them longer and more planar (two-dimensional). For example, it is possible to provide an inkjet recording head that is easy to provide multiple ejection ports and high-density mounting, has excellent mass productivity, and is inexpensive to manufacture.

As described above, using the electrothermal converter as the energy generating means, an ink jet recording head manufactured through a semiconductor manufacturing process is generally provided with a plurality of liquid flow paths corresponding to each discharge port. An electrothermal converter is provided as means for ejecting the liquid from the corresponding ejection port to form a flying droplet by applying thermal energy to the liquid filling the liquid channel for each liquid flow path. The channel adopts a structure in which liquid is supplied from a common liquid chamber communicating with each liquid channel.

FIG. 3 is a partially cutaway perspective view schematically showing a schematic configuration of the above-described ink jet recording head. In FIG. 3, the recording head 1 is provided with a substrate 102 through a semiconductor manufacturing process such as etching vapor deposition and sputtering. It comprises an electrothermal transducer 103 and an electrode 104 formed thereon, a partition part 105 for forming a liquid path 110, and a top plate.

The recording liquid (ink) 112 is supplied from a liquid storage chamber (not shown) through the ink supply pipe 107 to the common liquid chamber 10 of the recording head 101.
Supplied into 8. In FIG. 3, reference numeral 109 denotes an ink supply tube connector. The ink 112 supplied into the common liquid chamber 108
The liquid is supplied into the liquid passage 110 by capillary action, and is stably held by forming a meniscus at the discharge port 111 at the tip of the liquid passage 110.

Here, when electricity is supplied to the electrothermal converter 103, the liquid on the surface of the electrothermal converter 103 is heated, a foaming phenomenon occurs, and a droplet is discharged from the discharge port 111 by the energy of the foaming.

With the above configuration, a multi-type inkjet recording head can be configured with a high-density ejection port arrangement such as an ejection port density of 400 DPI.

FIG. 1 is a schematic diagram showing an ink supply system for the recording head 1 of FIG.

In FIG. 1, reference numeral 1 denotes a recording head, 54 denotes a discharge port surface (a front surface on which discharge ports are formed), 111 denotes a discharge port for ink discharge arranged on the discharge port surface, and 108 denotes a common liquid chamber. The discharge ports 111 are arranged at a predetermined pitch (density) throughout the recordable width of the target recording material 7 (FIG. 2). Has an electrothermal transducer (heating element) 103 that generates thermal energy
(FIG. 3) is provided. In addition, these fluid paths 110
Communicates with the common liquid chamber.

Therefore, by selectively driving the electrothermal transducer 103, the recording is performed without the main scanning of the recording head 1 itself.

The recording head is, for example, formed with a total of 4736 ejection openings at a density of 400 DPI (dots / inch). Therefore, the recording head is a high-density and wide multi-head capable of recording the vertical width of the standard A3 size at a time. It is configured.

Each liquid path 110 leading from the common liquid chamber 108 to each discharge port 111
(FIG. 3) shows a heating element 10 for generating ejection energy.
3 (FIG. 3) is provided, and by selectively driving the heating element based on the recording information, the recording droplets are ejected and fly to record an image on the recording material. In this case, printing can be performed without the main scanning of the print head 1 itself.

In FIG. 1, 55 is an ink supply tank for supplying ink (recording liquid) to the recording head 1, and 56 is a supply tank.
This is a main tank for refilling the ink into the ink tank 55, and the ink in the supply tank 55 is supplied to the common liquid chamber 108 of the recording head 1 through the ink supply pipe 107. Also supply tank 5
The replenishment of the ink into the tank 5 is performed by a pump 59 from a main tank 56 via a one-way replenishment rectifying valve 58.

Reference numeral 60 denotes a one-way recovery rectifying valve used during a recovery operation for recovering the ejection function of the recording head 1;
5 shows a circulation pipe in which the recovery rectifying valve 60 is interposed. Further, 62 indicates an electromagnetic valve interposed in the supply pipe 107, and 63 indicates an air vent valve of the supply tank 55.

In the recording head 1 and the ink supply system and the recovery system thereof configured as described above, when recording is performed, the electromagnetic valve 62 is used.
Is kept open, and the recording liquid (ink) in the supply tank 55 is supplied to the common liquid chamber 108 by its own weight.
The recording liquid in the common liquid chamber 108 is guided to a discharge port 111 through a liquid path (not shown).

In addition, at the time of a recovery operation performed to cool the recording head 1 while removing foreign matter such as air bubbles remaining in the common liquid chamber 108 and the supply system, the ejection port 54 is covered with a cap (not shown). By opening the recovery rectifying valve 60 and driving the pump 59, ink is sent to the common liquid chamber 108 by the circulation pipe 61, and at the same time, the recording head 1 is driven to Air bubbles are pushed out together with the ink, and the ink in the common liquid chamber 108 is further circulated to the supply tank 55 through the first ink supply pipe 107.

Further, when the ink is initially filled in the liquid passage 110 of each discharge port 111, the recovery pump 59 is driven with the electromagnetic valve 62 closed, and the ink is pressure-fed into the common liquid chamber 52 through the circulation pipe 61. In addition, bubbles and the like can be ejected from the ejection port 111 together with the ink.

FIG. 4 shows a recovery pump 59 for the above-described recovery operation in the ink jet recording apparatus described above with reference to FIGS.
4 is a graph showing an example of the timing of the driving of the recording head 1 and the driving of the recording head 1.

That is, in the present embodiment, in the recovery operation, when the recovery pump 59 is driven, at the same time, the electrothermal converter 103 (FIG. 3) in each liquid path 110 of the recording head 1 is driven to discharge ink. It is configured to discharge from the discharge port 111.

5 and 6 are plan views schematically showing a state of removing bubbles in the liquid passage 110 when the driving as shown in FIG. 4 is performed.

As shown in FIG. 4, when the recovery pump 59 is driven, at the same time, the recording head 1 is driven to discharge ink to each ejection port.
When the recording head 1 is ejected, bubbles 31 generated on the respective electrothermal transducers 103 by the driving of the recording head 1 as shown in FIG.
Then, small air bubbles (small bubbles) 25 (FIG. 9) in the liquid passage 110 are united (or absorbed), and as shown in FIG.
With the ink flowing out of the direction of arrow 32, the coalesced bubbles 31 are pushed out from the ejection port 111, and the small bubbles 25 are removed.

As described above, in the ink jet recording apparatus including the recording head 1 for discharging the droplet by the thermal energy and the flowing means 59 for causing the recording liquid in the recording head 1 to flow, the droplet of the droplet is By adopting a configuration in which ejection is performed, even if a small bubble 25 is generated in the liquid path 110 of the recording head 1, this can be reliably removed, and a recovery of the ink jet recording apparatus that can always perform stable ink ejection. A method is obtained.

FIG. 7 is a timing chart showing another relationship between the drive of the recovery pump 59 and the drive of the print head 1 in the recovery method (recovery operation) of the ink jet printing apparatus according to the present invention.

FIG. 4 shows a case where the drive of the recovery pump 59 and the drive of the recording head 1 are completely matched from the start time to the end time. However, when the present invention is carried out, it is not always necessary to make such complete match. Instead, as shown in FIG. 7, a drive timing for maintaining the simultaneity such as appropriately driving the other within one drive time may be adopted.

The recording head 1 is driven for the recovery operation under different driving conditions than during recording, for example, by appropriately increasing / decreasing the driving pulse width or dividing the driving pulse to give small bubbles. A) It is performed under another driving condition that bubbles can be foamed. However, depending on the recording head used and the environmental conditions, the driving conditions such as the driving pulse width may be the same as a result.

The present invention brings about an excellent effect particularly in a recording head and a recording apparatus of a bubble jet system among the ink jet recording systems.

The representative configuration and principle are preferably performed using the basic principle disclosed in, for example, US Pat. Nos. 4,723,129 and 4,740,796.

This method can be applied to any of the so-called on-demand type and continuous type. In particular, in the case of the on-demand type, it is arranged on a sheet or a liquid path holding a liquid (ink). By applying at least one drive signal to the electrothermal transducer, which corresponds to the recorded information and provides a rapid temperature rise exceeding nucleate boiling,
This is effective because thermal energy is generated in the electrothermal transducer, and the film is boiled on the heat-acting surface of the recording head. As a result, bubbles in the liquid (ink) can be formed in one-to-one correspondence with the drive signal.

By discharging the liquid (ink) through the discharge opening by the growth and contraction of the bubble, at least one droplet is formed.

When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,434,262 are suitable.

Further, if the conditions described in US Pat. No. 4,313,124 relating to the invention relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

As a configuration of the recording head, in addition to the combination configuration (a linear liquid flow path or a right-angle liquid flow path) of a discharge port, a flow path, and an electrothermal converter as disclosed in the above-mentioned respective specifications, a heat acting section A configuration using U.S. Pat. No. 4,558,333 and U.S. Pat. No. 4,459,600, which disclose a configuration in which the is bent, is also included in the present invention.

In addition, JP-A-59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, and an aperture for absorbing pressure waves of thermal energy. The present invention is also effective as a configuration based on JP-A-59-138461, which discloses a configuration in which is adapted to a discharge unit.

Further, as a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus, the length can be reduced by a combination of a plurality of recording heads as disclosed in the above specification. Either a configuration that satisfies the above or a configuration as a single recording head that is integrally formed may be used, but the present invention can more effectively exert the above-described effects.

In addition, a replaceable chip-type recording head that can be electrically connected to the apparatus main body and supplied with ink from the apparatus main body by being attached to the apparatus main body, or provided integrally with the recording head itself The present invention is also effective when a cartridge type recording head is used.

It is preferable to add recovery means for the printhead, preliminary auxiliary means, and the like, which are provided as components of the printing apparatus of the present invention, since the effects of the present invention can be further stabilized.

If these are specifically mentioned, for the recording head,
Capping means, cleaning means, pressurizing or suction means, preheating means using an electrothermal transducer or another heating element or a combination thereof, and performing a predischarge mode in which discharge is performed separately from recording. Is also effective for performing stable recording.

Further, the printing mode of the printing apparatus is not limited to the printing mode of only the mainstream color such as black, but may be a printing head integrally formed or a combination of a plurality of printing heads. The present invention is extremely effective for an apparatus having at least one of the full colors.

〔The invention's effect〕

As is apparent from the above description, according to the present invention, there is provided thermal energy generating means for generating thermal energy used for discharging ink, and recording is performed by discharging ink under driving conditions during recording. A method of recovering an ink jet recording apparatus, comprising: a head; and a fluid unit that circulates and supplies the ink in the recording head, wherein the ink is caused to flow in the recording head by operating the fluid unit. In parallel with the above, the thermal energy generating means is driven under a driving condition different from the driving condition at the time of recording to discharge ink from the recording head, so that small bubbles are generated in the flow path of the recording head. Even in such a case, there is provided a recovery method for an ink jet recording apparatus which can surely remove the ink and always perform stable ink ejection.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an ink supply system of an ink jet recording apparatus suitable for carrying out the recovery method according to the present invention, and FIG. 2 is a configuration of an ink jet recording apparatus suitable for carrying out the recovery method according to the present invention. Side view schematically showing an example,
FIG. 3 is a partially cutaway perspective view schematically showing the recording head in FIG. 2, FIG. 4 is a timing chart showing a driving example of the recovery pump and the recording head when performing the recovery method of the present invention, and FIG. FIG. 5 is a longitudinal sectional view schematically showing a state of driving start of the liquid path of the recording head driven based on FIG. 4, and FIG. 6 is a schematic view showing a state after a predetermined time has elapsed from FIG. FIG. 7 is a timing chart showing another example of driving a recovery pump and a recording head when the recovery method of the present invention is carried out, and FIG. 8 is a schematic diagram showing an ink supply system of a conventional ink jet recording apparatus. FIG. 9 is a longitudinal sectional view schematically showing an ink flowing state in a liquid path of a recording head of a conventional ink jet recording apparatus. In the following, reference numerals indicating major components in the drawings are listed. 1, 1 Bk, 1y, 1m, 1c: recording head (ink-jet head), 3: capping unit, 4: transport belt, 5: back platen, 7: recording material, 25:
Small bubbles, 31: Bubbles, 54: Discharge port surface, 55: Ink supply tank, 56: Main tank, 58: Rectifying valve, 59: Recovery pump, 60: Rectifying valve, 61: Circulation Tube, 62 solenoid valve, 103 electrothermal converter (thermal energy generator), 107
…… Ink supply pipe, 108 …… Common liquid chamber, 110 …… liquid path, 11
1 ... Discharge port, 112 ... Recording liquid (ink).

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B41J 2/165 B41J 2/175

Claims (1)

(57) [Claims] A printhead for providing a thermal energy generating means for generating thermal energy used for discharging the ink, the printhead discharging the ink under driving conditions at the time of printing, and performing printing; And a flow means for circulating and supplying the heat energy, wherein the thermal energy generation is performed in parallel with operating the flow means to flow the ink in the print head. And recovering the ink from the recording head by driving the unit under driving conditions different from the driving conditions at the time of recording.