JPH10202909A - Image forming equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the application of pressure to a suction means and prevent ink from flowing out by opening a lead-out channel between a cap member and a suction means and a communication channel between the cap member and outside air in an operation mode of operating a pressure pump by closing tightly an ink discharge area by the cap member. SOLUTION: A pressure pump 15 that supplies ink in an ink tank 14 to a recording head 11 by pressure operates for a preset prescribed duration but opens a communication valve 61 prior to finish time by a time T, stopping the pressure pump 15 during such time. By opening the communication valve 62, compressed air 108 is discharged out from a discharge pipe 53. Even after the pressure pump 15 is stopped, until the expansion of compressed air ends, the communication valve 62 is held open for a while, and then closed. Upon closure of the communication valve 62, the cap 101 is released. Discharge ink in the cap 101 and the suction pipe 7 is sucked forcibly by opening the communication valve 62 and operating the suction pump 51.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming an image on a recording medium, and more particularly, to using a cloth or the like as a recording medium and discharging a liquid such as ink onto the recording medium by an ink jet recording head. And an image forming apparatus for performing printing.

[0002]

2. Description of the Related Art Copiers, printers, and the like used together with a computer or a word processor, or used alone.
2. Description of the Related Art An image forming apparatus such as a facsimile is configured to record an image on a recording medium such as a sheet based on an image signal. On the other hand, in recent years, with respect to the material of the recording medium, paper or a resin thin plate such as an ordinary recording medium, for example, OHP paper,
In addition, it is required to use thin paper or processed paper, for example, paper with perforated holes or perforated paper for filing, paper of any shape, or woven fabric. Also, as for the size of the recording medium, large-sized woven fabrics used for sheets and clothing for publicity have been required.

[0003] An ink jet recording head (hereinafter, also simply referred to as a recording head) performs recording by discharging a liquid such as ink onto a recording medium from a fine discharge port. The discharge port of
Desired printing is performed by independently controlling the ejection of ink from each ejection port. As an image forming apparatus equipped with such a recording head and performing image recording (hereinafter, also referred to as printing) on the entire recording medium, a serial type in which the recording head scans in a direction crossing the direction in which the recording medium is transported is used. And a full-line type in which one or more recording heads are arranged at a length corresponding to the entire width of the recording medium.

In a serial type image forming apparatus, after a recording medium is set at a predetermined position, an image is recorded by a recording head mounted on a carriage that moves along the recording medium based on an image signal, and one scan or recording is performed. After the recording for the print width of the head is completed, the recording medium is conveyed by the print width, and thereafter, the operation of recording the image of the next line is repeated, whereby the image recording of the entire recording medium is performed. Further, in a full-line type image forming apparatus, a recording head is fixed on a conveying section of the recording medium so as to cover the entire width of the recording medium, and an image signal is transmitted when the recording medium is conveyed under the recording head. The recording head performs ejection based on the above, so that the entire image is recorded only by the passage of the recording medium.

[0005] As described above, a typical image forming apparatus capable of performing recording on various recording media is an image forming apparatus using an ink jet recording head that performs recording by discharging ink from discharge ports. . In this apparatus, various color images can be printed by combining each color with a multicolor ink corresponding to each recording head.

In recent years, for such an image forming apparatus,
There is a demand for an improvement in the recording speed of the entire image and a reduction in cost. In order to respond to this, in the above-described serial type image forming apparatus, the recording head is made longer to increase the printing width, and the printing area in one scan is enlarged to improve the recording speed. Further, in the full-line type image forming apparatus, similarly, by increasing the length of the recording head, the number of recording heads covering the entire width of the recording medium is reduced, the number of components is reduced, and the cost of the apparatus is reduced. By eliminating the scanning operation of the print head as compared with the serial type, the operation time is shortened and the printing speed is improved.

In order to maintain good recording quality, the ink jet recording head removes foreign matter that has entered the discharge port, or removes ink that has remained in the discharge port for a long time and has increased in viscosity above a predetermined value. In addition, it is necessary to periodically perform an operation of recovery for removing ink droplets and dust attached to the vicinity of the discharge port. In an image forming apparatus using a long recording head, for example, Japanese Patent Application Laid-Open
A recovery operation has been performed as disclosed in US Pat. That is, while the ejection area of the recording head is sealed by the cap means, the ink is pressurized using the supply means for supplying the ink to the recording head, whereby the ink is forcibly discharged from the ejection port of the recording head. At the same time, an operation of circulating the ink in the path is performed,
The ink in the cap means has been discharged from the outlet connected to the cap means by the suction means.

[0008]

However, in the above-described conventional image forming apparatus, a suction pump is used as suction means for discharging a liquid such as ink in the cap means to the outside. As for the suction pump, a turbo type that converts energy into fluid by a rotating impeller, or a positive displacement type that performs energy conversion by a pushing action of a piston, a plunger, a rotor, etc. has high energy conversion efficiency, and is generally used. It is used. The transfer of the liquid is performed by flowing the liquid from the primary side (the side entering the suction pump) to the secondary side (the side exiting the suction pump) via the suction pump by a pipe member such as a tube or a pipe. By the way, the cap means and the suction means are directly connected by a piping member (lead-out part), and in the recovery operation, the pressure generated by the supply means is applied to the suction pump via the lead-out part. At this time, when the operation of the suction pump is stopped, the suction pump itself causes flow resistance, but there is no damping action, and the liquid flows out to the secondary side, that is, leaks, and as a result, ink from the supply unit is excessively discharged from the recording head. There was a problem that was discharged to the.

Further, in order to seal (cap) the recording head by cap means and prevent the above-mentioned leak,
The following problem occurs when ink is pressurized by driving a supply unit in a state where a valve member having a partition function is arranged in the outlet section and the outlet section is blocked. First, there is a considerable amount of air in the volume inside the cap means before capping, and in the capping state, the cap means seals the discharge port and air. From this state, the pressure applied to the ejection port by pressurizing the ink gradually increases from 0 and reaches a predetermined value. Then, the ink is gradually discharged, and the air volume in the cap means decreases, so that the pressure in the cap means gradually increases. The ink is discharged into the cap until the pressure applied to the ejection port by the supply means is balanced with the pressure of the air in the cap means. Here, when the pressurizing operation of the ink is stopped, the pressure applied to the discharge port by the supply unit returns to the original pressure, that is, 0, but at the same time, the air compressed in the cap unit up to the original air volume. Swell. Since the expansion occurs rapidly, air may enter the discharge port, and as a result, air bubbles remain in the discharge port,
In printing performed after the recovery operation, there is a problem that ejection failure occurs.

Therefore, an object of the present invention is to solve the above-mentioned problems, and (1) to prevent the leakage of ink from the suction means,
(2) An object of the present invention is to provide an image forming apparatus provided with a mode for performing a recovery operation for preventing the air in the cap means from flowing back to the discharge port and improving the discharge of the recording head.

[0011]

In order to achieve the above object, the present invention uses a recording means having a plurality of nozzles for discharging ink and a liquid chamber provided in common with the nozzles for temporarily storing ink. In an image forming apparatus that performs recording by discharging ink onto a recording medium, a cap unit having a cap member that seals an ink discharge area of the recording unit as necessary, and an ink tank that stores ink. Supply means having a pressurized flow path connecting the liquid chamber to the ink tank, a pressurized pump for transferring ink from the ink tank via the pressurized flow path to the recording means, and a liquid in the cap member. And a suction means having a lead-out path for leading the ink to the outside and operating as necessary. A first valve member for communicating an outlet path between the cap member and the suction means, the first valve member having an operation mode for operating the pressurizing pump by sealing a region, and the cap member and the outside air. And a second valve member that communicates with the image forming apparatus.

[0012] Further, the lead-out path is branched into two, and the first valve member and the second valve member are respectively provided on the branched lead-out paths. Furthermore, immediately before the operation of the pressurizing pump stops, the second valve member is operated.

[0013]

According to the present invention, the valve member between the cap means and the suction means does not apply pressure to the suction means when the supply means is pressurized, so that ink does not flow out through the suction means. By operating the communication means immediately before the end of the pressurization of the supply means and communicating the cap means with the outside air, the expansion of the air temporarily compressed in the outlet portion is released to the outside air side, and the air is discharged to the discharge port of the recording head. Does not penetrate.

[0014]

FIG. 1 shows an embodiment of the image forming apparatus of the present invention.
This will be specifically described with reference to FIG.

(Embodiment 1) FIG. 1 is a perspective view showing the structure of an ink jet recording apparatus main body, and FIG. 2 is a sectional view showing a main part. The image forming apparatus of the present embodiment is an ink jet recording apparatus that performs recording by discharging ink downward in the drawing onto a recording medium such as a cloth wound in advance. 1 is a printer unit for recording an image on the recording medium A, 2 is a conveying unit for intermittently conveying the recording medium A by a predetermined amount (recording length L), and 3 is a unit for feeding out a continuous recording medium A wound in advance. A feeding unit 4 and a winding unit 5 for winding the recording medium A;
Denotes a drying unit that dries until the recording medium A after image recording can be wound up. The recording medium A is fed from the feeding unit 3, passes through the transport unit 2 and the drying unit 5, and is wound around the winding unit 4. The printer unit 1 is provided to face the transport unit 2.

As will be described later, a total of 16 recording heads 11 and 12 of an ink jet recording system for discharging and recording ink are provided. It is mounted on a carriage 10. The printer unit 1 supports two scanning rails 1a and 1b so as to be orthogonal to the conveying direction of the recording medium A. The head carriage 1 reciprocates on the scanning rails 1a and 1b in the directions indicated by arrows P1 and P2. Move. At the time of reciprocation, the recording heads 11 and 12 print on a continuous recording medium A (printing in one scan) = (predetermined recording length L) × (recording medium A
Is repeatedly printed in the range of width W).

In this recording apparatus, image data is distributed to the upstream recording head 11 and the downstream recording head 12 on the transport section 2 by 50% and printed, and the entire image data is recorded on the recording medium A. . That is, 50% of the image data is printed by the upstream recording head 11 and the remaining 50% of the image data is printed by the downstream recording head 12 when the recording medium A is intermittently fed. , 1
2 are superimposed. The area of the recording medium A indicated by a perspective in FIG. 1 is a recorded area.

FIG. 3 shows the internal structure of the recording heads 11 and 12. The recording head employed in the above-described ink jet recording method has an ejection port 100 for ejecting a liquid (ink).
1. Nozzles (liquid paths) 1002 communicating with the discharge ports 1001 provided for the respective discharge ports 1001, liquid chambers 1003 for distributing ink to the nozzles 1002, energy acting parts 1004 disposed for the respective nozzles 1002, and their functions. Part 10
An energy generating element 1005 for generating droplet formation energy (ejection energy) to be applied to the liquid at the portion 04, a supply port 1006 for supplying ink to the liquid chamber 1003, and an ink tube 1007 connected to the supply port 1006 It has. In this recording head, a plurality of ejection ports 1001 are arranged in a line, thereby forming an ejection port surface 1008. Although only a part of the recording head is shown in FIG. 3, in actuality, for example, the recording head is a long recording head having 100 to 1000 ejection ports 1001, and supply ports 100 are provided at both ends.
6 are provided. During normal printing, the ink is supplied from both supply ports, but during pressurized supply described later, ink is supplied under pressure from one supply port, and the ink is circulated from the other supply port and returns to the ink tank. Has become. Needless to say, the recording head may be a recording head having one supply port and not circulating in the ink tank, and the ink flow path may be formed by one supply port at the time of pressurized supply and printing. In this embodiment, a recording head having two supply ports will be described.

As an energy generating means for generating such energy, a recording method using an electromechanical transducer such as a piezo element, an electromagnetic wave such as a laser or the like is applied to generate heat,
A recording method using energy generating means for discharging liquid droplets by the action of the heat generation, or recording using energy generating means for discharging liquid by heating liquid by an electrothermal converter such as a heating element having a heating resistor. There are methods. Among them, a recording head used in an ink jet recording method in which a liquid is discharged by thermal energy can discharge liquid droplets for recording to form discharge droplets at a high density, so that a high density can be achieved. It is possible to record the resolution. Among them, a recording head using an electrothermal transducer as an energy generating means can easily be made compact, and has the advantages of IC technology and microfabrication technology, which have recently made remarkable progress in technology in the field of semiconductors and markedly improved reliability. This is advantageous because it can be used for two reasons, high-density mounting is easy, and the manufacturing cost is low.

The ink supplied to the recording heads 11 and 12 is supplied from a supply device 13 provided separately from the frame of the printer unit 1. The supply device 13 has ink tanks 13a to 13h for each ink color to be used, and can store a total of eight colors. The recording heads 11 and 12 in each row correspond to any one of these eight colors. The ink of each color is supplied to a total of two recording heads, that is, an upstream recording head 11 and a corresponding downstream recording head 12.

The ink is supplied by a supply pump for each ink.
Via the tube 1c crawled into the printer unit 1,
It is supplied to the corresponding recording heads 11 and 12. At the time of printing, the ink is automatically supplied to the recording head by the amount discharged from the recording head by the capillary action. Note that, for example, inks having substantially different colors such as dark ink and light ink are stored in different ink tanks, even if they have the same color.

FIG. 4 shows a state before capping by an ink supply system and a cap means to be described later (cap released state). The recording heads 11 and 12 only distinguish between the upstream side and the downstream side in the transport direction of the recording medium A. Since the configuration of the ink path is the same, the downstream side is omitted and the upstream side is omitted. Will be described below. The ink tanks represented by 13a to 13h are represented by the ink tank 14 as a representative.

A pressure pump 15 for supplying ink from the ink tank 14 to the recording head 11 under pressure is provided.
Further, the pressurizing pump 15 and the recording head 11 are connected to each other, and a pressurizing tube 16 serving as an ink flow path during pressurized supply.
From the recording head 11 to the ink tank 14 during pressurized supply.
And a circulation tube 17 serving as a flow path for returning the ink to the ink tank. The ends of the pressure tube 16 and the circulation tube 17 on the ink tank 14 side are respectively submerged in the ink.

The ink from the ink tank 14 is supplied with a positive pressure by the pressurizing pump 15 at the time of pressurized supply, so that the pressurizing tube 16 → the liquid chamber 1003 of the recording head 11 and the nozzle 100
2 → circulation tube 17 → ink tank 14 The pressurized ink supply performed by the pressurizing pump 15 is divided into (1) a pressurizing mode and (2) a circulation mode. Pressurization mode is
Discharge port 1001 with bubbles in nozzle 1002 together with ink
This is a mode for discharging from the cap, and is performed with the cap released. In the circulation mode, bubbles in the liquid chamber 1003, the pressure tube 16, and the circulation
This is a mode for returning to, and is performed by capping as shown in FIG.

The printer unit 1 includes recording heads 11 and 12
Recovery device 2 so that the user can always perform good printing
0 is attached. The recovery device 20 is capable of (1) preventing an increase in the viscosity of the ink, (2) removing ink adhering to the surface of the discharge port, and (3) removing air bubbles in the discharge port, which cause unstable ink discharge. This is for obtaining ejection stability, and includes a cap section 100, a wipe section 200, a preliminary ejection section 300, a tank section 400, a pump section 500, and a discharge section 600.

First, the cap section 100 will be described. The cap unit 100 is provided so as to face the position of the recording head at the home position of the carriage 10, and the cap 101 has a number corresponding to the number of the recording heads 11 and caps the individual recording heads. The home position is the end of the reciprocating movement of the head carriage 10, a position where the head carriage 10 is stopped when printing is not performed, and a position deviated from the recording medium A. Each cap 101 caps the ejection port surface of the recording head when printing is stopped in order to prevent evaporation of ink, intrusion of foreign matter into nozzles, and the like.

In this embodiment, since there are 16 recording heads, 16 caps 101 are also provided. Cap 10
Numeral 1 is made of a rubber-like elastic member such as fluorine, silicon, or chlorinated butyl, and enhances the adhesion and airtightness with the recording head 11 at the time of capping. Each cap 101 is fixed to a mounting portion 102a of the holder 102.
FIG. 5 is a diagram illustrating a capping state of one recording head 11 and a cap 101 that forms a pair with the recording head 11, and is a cross-sectional view along the longitudinal direction of the recording head 11. The recording head 11 on the upstream side and the recording head 12 on the downstream side with respect to the transport direction of the recording medium A are each paired with the cap 101, and the capping state is the same. The configuration of the holder 102 on the upstream side will be described with reference to FIGS.

In FIG. 6, reference numeral 111 denotes a support plate for fixing the holder 102; 112, a guide rail for guiding the support plate 111 up and down; 113, an air cylinder as a driving source for vertically moving the support plate 111; Rail 1
12. Side plates supporting the air cylinder 113. The cap 10 is moved up and down by the air cylinder 113.
1 moves 16 at the same time when the carriage 10 is at the home position. The holder 102 has abutting portions 102c, 10c at the upper ends at both ends in the longitudinal direction.
2d (see FIG. 4) is formed, and a rotating shaft 102e is provided at the center in the longitudinal direction of the cap 101. The lower end portions 18c and 18d of the head holder 18 for attaching the recording head 11 in the longitudinal direction of the recording head are formed. At the end, it turns in the direction of arrow R around the turning shaft 102e (see FIG. 4).
Capping. The tip portion 101a where the cap 101 contacts the ejection port 1001 of the recording head 11 is
02 protrudes by a height d from the abutting portions 102c and 102d, and the cap 101 is crushed by the height d during capping.

A receiving portion 104 is formed around the mounting portion 102a of the cap 101.
Receives the ink in the pressure mode, and discharges the ink to the liquid collecting member 105 via the drain 102b provided at the end of the holder 102. The liquid collecting member 105 is attached to each of the holders 1.
02 is collected, and the ink flows from a discharge pipe 105a to a discharge section 600 provided below the cap section 100.
Further, the holder 102 is provided with a suction tube 107 for leading the liquid inside the cap 101 to the outside. The suction pipe 107 is branched at a branch portion 109 into a communication valve 61 with the suction pump and a communication valve 62 with the atmosphere. A suction pump 51 is provided at the end of the communication valve 61, and the ink flows from a discharge pipe 52 to a discharge unit 600.

FIG. 5 shows the positional relationship between the recording head 11 and the cap 101 in the circulation mode. The recording head 11 is capped facing the cap 101. If the inkjet recording apparatus is stopped and left for a long time, gas components dissolved in the ink in the nozzle 1002, the liquid chamber 1003, or the ink in the ink tube are separated to generate bubbles, and the next operation is performed. Sometimes, it is not impossible to prevent stable ejection. For this reason, as described above, the pressurizing pump 15 provided in the supply device 13 is driven at the start of printing in the circulation mode or at every predetermined number of reciprocations at the time of printing, and bubbles in the liquid chamber 1003 and the ink tube are removed. Return to the tank 14 to remove bubbles. The operation of each unit in the circulation mode will be described with reference to the timing chart of FIG.

In the circulation mode, capping is performed. First, the air communication valve 62 is opened, and the cap 101 caps the recording head 11 in this state. This is because the air part 101b in the cap 101 is
01 reduces the volume of air by the nozzle 1002
In order not to be pushed into. The above height d
When the cap 101 is crushed and the capping is completed, the communication valve 62 is closed, the discharge port surface 1001 is shut off from the outside air, and is sealed. At the same time or slightly later, the pressure pump 15 is operated, and the ink is discharged from the discharge port 1001. The pressure generated by the pressurizing pump 15 rises in the first short time as shown in FIG. 8 and thereafter reaches a certain pressure. When the pressurizing pump 15 stops, the pressure returns to the original level. As such a pressurizing pump, a turbo centrifugal pump of a type that generates a constant pressure is suitable. Due to the forced discharge by pressurization, the discharged ink 10 as shown by the hatched portion in FIG.
6 is filled in the cap 101 and the suction tube 107. At the same time, the air having the same pressure as the external atmosphere existing up to that point is compressed by the discharged ink 106 because the suction pipe 107 is blocked by the communication valves 61 and 62.
08.

The pressurizing pump 15 operates for a predetermined period of time, but the communication valve 61 is opened a time T before the end thereof, during which the pressurizing pump 15 stops.
When the communication valve 62 is opened, the compressed air 108 flows out of the discharge pipe 53 to the outside. In FIG. 5, for convenience of explanation,
Although the discharged ink and the compressed air are shown separately above and below, the discharged ink may be in a state in which minute compressed bubbles are mixed (a mixed phase liquid). Even in such a state, by opening the communication valve 62, the mixed phase liquid containing the compressed air is opened to the discharge pipe 53 side, and air does not enter the discharge port 1001. Even after the stop of the pressurizing pump 15, until the expansion of the compressed air ends,
The communication valve 62 has been open for a while and then closed. Communication valve 6
As soon as 2 is closed, the cap 101 is released. Then, the communication valve 62 is opened, the suction pump 51 is operated, and the ink discharged from the cap 101 and the suction pipe 107 is sucked. Since the discharged ink cannot be completely removed only by opening the communication valve 62, the suction is forcibly performed.
In this manner, by opening the communication valve 62 immediately before the operation of the pressurizing motor is completed, the compressed air in the suction pipe does not enter the discharge port, and discharge failure can be prevented in the recovery operation.

During the operation of the suction pump 51, the head carriage 10 is moving to the next wiping unit 200. The wiping unit 200 has a function of wiping (wiping) the discharge port surface 1006 with an absorber made of a porous material. This is performed in order to prevent the ink mist generated by the ejection during printing from adhering to the ejection port surface 1006 and approaching the ejection port 1001 to make the ejection unstable.
After the end of the wiping, the head carriage 10 moves to the next preliminary ejection section 300.

The pre-discharge unit 300 has a function of giving a predetermined drive pulse before the start of printing and receiving ink droplets when ink is discharged from all discharge ports (this is called pre-discharge). After the preliminary ejection, the head carriage 10 moves onto the recording medium A and performs printing. During printing, the cap unit 100 and the wipe unit 2
00, the cleaning liquid is selectively supplied to the preliminary discharge section 300. In each part, a portion to which ink has adhered, that is, in the cap portion 100, the cap 101, the wipe portion 200
Then, the absorber and the preliminary ejection unit 300 clean the ink droplet receiving unit.

Next, the relationship between the pump section 500 and the cap section 100 will be described with reference to FIG. In FIG.
FIG. 2 shows a perspective view of the configuration of the entire cap unit 100. The suction pipe 107 extends from each of the 16 holders 102,
Blocking is performed on the upstream side and the downstream side, and eight suction pipes are gathered in one suction pipe 109a below. In the same manner as described above, the branch portion 109 branches into the communication valves 61 and 63 for the pump and the communication valves 62 and 64 for the atmosphere. 54 is
This is a downstream suction pump. The pump unit 500 is located below the cap unit 100, and performs suction while facilitating discharge in consideration of a height difference. Also, the discharge pipes 52, 5
3 is connected to the discharge part 600. Since the circulation mode is performed simultaneously for each of the blocked caps, the ink does not flow from one cap to another via the discharge pipe.

In the above-described configuration, providing a suction pump and a communication valve corresponding to each cap increases the cost. Therefore, the suction pipes are appropriately divided into eight (in this embodiment, eight blocks) and assembled. Let me. Communication valves 61, 62, 6
Reference numerals 3 and 64 use electromagnetic valves whose opening and closing timing can be controlled by control signals. As the suction pumps 51 and 54, in order to suck a predetermined amount of ink of the volume of the known suction tube, a fixed-volume type using a type driven by a pulse or a diaphragm or a bellows having a constant number of revolutions per time is used. Pumps are suitable.

The discharge unit 600 has a function of receiving liquid when discharging the ink from the cap unit 100 and the ink sucked by the pump unit 500, and a function of discharging the ink after receiving the liquid to the outside of the apparatus. The liquid receiving section 601 is provided below the recovery device 20 and flows the discharged liquid through the hose 602 to the outermost lower side groove 603 (see FIG. 2).

(Embodiment 2) FIG. 9 is a view showing another configuration of the discharge pipe. The recording head, the cap, and the like are drawn as a cross section orthogonal to the transport direction of the recording medium. Although only four recording heads and caps are shown in the figure, eight recording heads and caps are actually grouped together as in the configuration of FIG. Numeral 70 denotes a check valve provided in each discharge pipe 107, which is arranged in front of the merge pipe 71 in which the discharge pipes are assembled. The check valve 70 is a member having a function of flowing a fluid from the cap 101 side to the junction pipe 71 but not flowing in the reverse direction. The check valve 70 is a valve seat made of any of silicon rubber, ceramic balls, fluorine resin, and the like, and allows fluid to flow only in one direction. Other configurations and timings are the same as those in the first embodiment. In this way, by providing the check valves in the assembled discharge pipes, the circulation mode can be performed only for a specific printhead, not for eight printheads at the same time. This is effective when the ratio of the specific color to the image to be printed is large and the printing ratio of the recording head of another color is low.

[0039]

As described above, according to the present invention,
In the state where the recording head is capped, when the ink is pressurized by the supply means by the valve member between the cap means and the suction means, no pressure is applied to the suction means, and the outflow of the ink through the suction means is performed. Disappears. Therefore, it is possible to eliminate an excessive amount of ink discharged in the circulation mode. By operating the communication means immediately before the end of the pressurization of the supply means and communicating the cap means with the outside air, the expansion of the air temporarily compressed in the outlet portion is released to the outside air side, and the air is sent to the nozzle of the recording head. No intrusion. Therefore, it is possible to eliminate ejection failure due to bubbles.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a configuration of an ink jet recording apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of the inkjet recording apparatus of FIG. 1;

FIG. 3 is a perspective view illustrating a configuration of a recording head.

FIG. 4 is a diagram illustrating a configuration of an ink path and a state in which a cap is released.

FIG. 5 is a diagram illustrating a circulation mode.

FIG. 6 is a configuration perspective view of a cap section and a pump section.

FIG. 7 is a timing chart of a recovery operation.

FIG. 8 is a pressure time curve diagram of a pressurizing pump.

FIG. 9 is another embodiment showing a configuration of a discharge pipe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printer part 2 Conveyance part 3 Feeding part 4 Winding part 5 Drying part 10 Head carriage 11, 12 Recording head 13 Supply device 20 Recovery device 51, 54 Suction pump 52, 53 Discharge pipe 61, 62, 63, 64 Communication valve 100 Cap unit 101 Cap 102 Holder 104 Reception unit 107, 109a Suction tube 109 Branch unit 200 Blade unit 300 Pre-discharge unit 400 Tank unit 500 Pump unit 600 Discharge unit

Claims (5)

[Claims] 1. Recording is performed by ejecting ink to a recording medium using a recording means having a plurality of nozzles for ejecting ink and a liquid chamber provided in common with the nozzles and temporarily storing ink. In the image forming apparatus, a cap unit having a cap member that seals an ink ejection area of the recording unit as necessary, an ink tank that stores ink, a pressurized flow path that connects the liquid chamber to the ink tank, A supply unit having a pressurizing pump for transferring ink from the ink tank to the recording unit via the pressurizing flow path; and a lead-out path for leading out the liquid in the cap member to the outside as necessary. And a suction means for operating the pressurizing pump with the cap member sealing the ink discharge area. A first valve member for communicating a lead-out path between the cap member and the suction means, and a second valve member for communicating the cap member with outside air. An image forming apparatus comprising: 2. The image forming apparatus according to claim 1, wherein the leading path is branched into two, and the first valve member and the second valve member are provided on the branch leading paths. apparatus. 3. The image forming apparatus according to claim 1, wherein the second valve member is operated immediately before the operation of the pressurizing pump is stopped. 4. The image forming apparatus according to claim 1, wherein a check valve is provided in the outlet path upstream of the first valve member and the second valve member. 5. The image forming apparatus according to claim 1, wherein the second valve member is opened before closing the ink ejection area with the cap. When closing the valve member, actuate the pressurizing pump, before stopping the operation of the pressurizing pump, after opening the second valve member again, stopping the operation of the pressurizing pump, The image forming apparatus is configured to close again, open the first valve member, and operate the suction unit.