JP4710356B2 - Droplet discharge device - Google Patents

Description

  The present invention relates to a droplet discharge device that discharges droplets, and more particularly to a droplet discharge device that is optimal for forming an image by discharging ink droplets.

  In an inkjet recording device, dust (dust) mixed in the ink and bubbles generated in the ink are the cause of ejection failure and increased flow path resistance. Removing the dust and bubbles maintains print quality. It is important to do. Conventionally, as a measure for removing dust in ink, it is common to provide a filter in an ink supply line (see, for example, Patent Documents 1 to 4). Among these, as a countermeasure for removing bubbles in the ink, it is known to discharge the bubbles by circulating the ink in the ink supply path (see, for example, Patent Document 1). Hereinafter, the prior art will be described with reference to the accompanying drawings by giving specific examples.

  As shown in FIG. 19, the conventional ink jet recording apparatus 212 disclosed in Patent Document 1 includes a sub tank 264 including a first ink chamber 264L and a second ink chamber 264U separated by a filter 266, and ink droplets. An ink jet recording head 233 for discharging, a cap 288 for receiving ink droplets discharged from the ink jet recording head 233, a replaceable cartridge 240 as a main ink supply source, a waste ink tank 296 for storing ink not to be reused, An ink circulation pump 274 and six valves V1 to V6 are provided. When the ink is circulated, the pump 274 is driven, the valves V 2 and V 3 are opened, and the ink in the inkjet recording head 233 is sucked through the cap 288.

  However, conventionally, ink is circulated through the cap 288 that frequently comes into contact with the atmosphere, and ink is sucked from the ejection nozzles of the inkjet recording head 233 in order to circulate the ink. For this reason, dust such as paper dust that has adhered to the cap 288 moves to the sub tank 264, and if there are bubbles or dust between the sub tank 264 and the flow path in the head, the ink jet recording head 233 There was a problem that it may be caught by the discharge nozzle and cannot be removed.

This problem often occurs not only in the ink jet recording apparatus but also in a liquid droplet ejection apparatus that ejects liquid droplets.
JP 2003-266745 A Japanese Patent Laid-Open No. 02-281960 Japanese Patent Publication No. 08-207308 JP 2002-321380 A

  In view of the above-described facts, an object of the present invention is to provide a droplet discharge device capable of removing foreign matters such as dust and bubbles in a liquid without going through the discharge nozzle of a droplet discharge head.

Invention of claim 1, the liquid chamber and the liquid droplet discharge head for discharging a discharge nozzle is formed droplets communicating with the liquid chamber from the discharge nozzle, a tank that stores the liquid, said tank A filter section through which the tank is divided into a downstream chamber and an upstream chamber and a liquid passes, a first line connecting the liquid chamber and the downstream chamber, and the liquid chamber and the upstream chamber . and a second line connecting, wherein the second line, and a pump for flowing the liquid toward the tank from the liquid chamber, a bypass line opening and closing valve is provided with bypassing said pump, said A branch pipe branched from the second line on the upstream chamber side of the bypass line and connected to the downstream chamber; and a three-way valve provided at a branch point between the branch pipe and the second line. It is, at the time of discharge of the droplet, the pump The on-off valve to open is stopped, and said connecting and said branch pipe and the second line as well as blocking the connection between the upstream chamber and the second line three-way valve, said from the downstream chamber first The liquid is supplied to the liquid chamber through one line , and the liquid is supplied from the downstream chamber to the liquid chamber through the branch pipe and the second line. When the liquid is circulated, the pump is driven and the on-off valve was closed, and, by interrupting the connection between the branch pipe and the second line with connecting the upstream chamber and the second line by the three-way valve, the liquid stored in the upstream chamber, the It is circulated to the upstream chamber through the downstream chamber, the first line, the liquid chamber, and the second line.

  The tank may be a sub tank (reservoir tank).

According to the first aspect of the present invention, at the time of discharging droplets, the pump is stopped and the on-off valve is opened, and the connection between the second line and the upstream chamber is blocked by the three-way valve , and the second line Connect to the branch pipe . Thus, with the liquid through the first line from the downstream chamber is supplied to the liquid chamber of the liquid droplet ejection head, the liquid is supplied to the liquid chamber of the liquid droplet ejection head through the branch pipe and the second line from the downstream chamber. Therefore, at the time of discharging a droplet, the liquid flows from the two lines into the liquid chamber of the droplet discharge head. As a result, the pressure loss is greatly reduced as compared with the conventional case, so that the liquid flow rate to the liquid chamber at the time of discharge can be maintained even if the liquid pressure is reduced as compared with the conventional case. Moreover, since it is not necessary to increase the pipe diameter of the first line or the second line, the apparatus does not increase in size. Further, the liquid in the downstream chamber is a liquid that has passed through the filter portion during the circulation of the liquid, and foreign matters such as dust are removed. Accordingly, foreign matter such as dust supplied to the liquid chamber of the droplet discharge head during ink discharge is suppressed.
On the other hand, when the liquid is circulated, the pump is driven, the open / close valve is closed, the second line and the upstream chamber are connected by the three-way valve, and the connection between the second line and the branch pipe is cut off. The liquid stored in the upstream chamber is circulated to the upstream chamber through the downstream chamber, the first line, the liquid chamber, and the second line. Therefore, dust and bubbles in the liquid can be removed by the filter unit without passing through the discharge nozzle of the droplet discharge head.

Further, since the above-described pump is provided in the second line, when the pump is driven to circulate the liquid for discharging bubbles in the liquid, a suction force acts on the liquid chamber of the droplet discharge head. Therefore, compared with the case where liquid is pumped and circulated through the droplet discharge head, liquid leakage due to application of pressure does not occur from the connection portion or joint portion of the flow path or the discharge nozzle.

The invention according to claim 2 is characterized in that the rotation direction of the pump can be switched.

  Thereby, since the liquid flow direction during the circulation of the liquid can be switched to the reverse direction, it is easy to remove the bubbles in the first line and the second line.

The invention described in claim 3 is characterized in that image formation is performed using an ink liquid as a liquid.

  Thereby, an image forming apparatus capable of forming a good image can be realized.

  According to the present invention, a droplet discharge device that can remove foreign matters such as dust and bubbles in a liquid without going through the discharge nozzle of a droplet discharge head is realized.

  Hereinafter, an ink jet recording apparatus will be exemplified as a droplet discharge apparatus, and an embodiment of the present invention will be described. In the second and subsequent embodiments, the same components as those already described are denoted by the same reference numerals and description thereof is omitted.

[First Embodiment]
First, the first embodiment will be described.

(overall structure)
FIG. 1 shows an ink jet recording apparatus 12 according to a first embodiment of the present invention. A paper feed tray 16 is provided in the lower part of the casing 14 of the ink jet recording apparatus 12, and the sheets P stacked in the paper feed tray 16 can be taken out one by one by a pickup roll 18. The taken paper P is transported by a plurality of transport roller pairs 20 constituting a predetermined transport path 22. Hereinafter, the term “transport direction” simply refers to the transport direction of the paper P that is a recording medium.

  Above the paper feed tray 16, an endless transport belt 28 stretched around a drive roll 24 and a driven roll 26 is disposed. A recording head array 30 is disposed above the conveyor belt 28 and faces the flat portion 28F of the conveyor belt 28. This opposed area is an ejection area SE where ink droplets are ejected from the recording head array 30. The sheet P transported along the transport path 22 is held by the transport belt 28 and reaches the discharge area SE, and ink droplets corresponding to image information are attached from the recording head array 30 in a state of facing the recording head array 30. The

  Then, by rotating the paper P while being held by the transport belt 28, the paper P can be passed through the discharge region SE a plurality of times, and so-called multipass image recording can be performed. Therefore, the surface of the conveyance belt 28 is a circulation path of the paper P in the present invention.

For example, the transport belt 28 is made of a semiconductive polyimide material (surface resistance value 10 ¹⁰ to 10 ¹³ Ω / □, volume resistance value 10 ⁹ to 10 ¹² Ω · cm), thickness 75 μm, width 380 mm, circumference What was shape | molded in length 1000mm can be used. Moreover, as the drive roll 24 and the driven roll 26, as an example, a φ50 mm SUS roll can be used.

  Further, without providing the conveyor belt 28, for example, a recording medium (paper P) may be sucked and held on the outer periphery of a conveyance roller formed in a cylindrical shape or a columnar shape and rotated. However, when the conveyor belt 28 is used as in the present embodiment, the flat portion 28F is formed, so that the recording head array 30 can be arranged corresponding to the flat portion 28F, which is preferable.

  In this embodiment, the recording head array 30 has a long shape in which the effective recording area is equal to or larger than the width of the paper P (the length in the direction orthogonal to the transport direction), and is yellow (Y) and magenta (M). , Cyan (C), and Black (K), four inkjet recording head units 32 (hereinafter simply referred to as head units 32) corresponding to the four colors are arranged along the transport direction to record full-color images. It is possible. The method of ejecting ink droplets in each head unit 32 is not particularly limited, and a known method such as a so-called thermal method or piezoelectric method can be applied.

  The inkjet recording head 33 (see FIGS. 5 and 6) constituting each head unit 32 is controlled by a head controller 60. For example, the head controller 60 determines the ejection timing of the ink droplets and the ink ejection port (nozzle) to be used according to the image information, and sends a drive signal to the inkjet recording head 33.

  The recording head array 30 may be stationary in a direction orthogonal to the transport direction. However, if the recording head array 30 is configured to move as necessary, an image with higher resolution can be obtained by multi-pass image recording. Or failure of the ink jet recording head 33 is not reflected in the recording result.

  Four maintenance units 34 corresponding to the respective head units 32 are arranged in the vicinity of the recording head array 30 (in this embodiment, both sides in the transport direction). When performing maintenance on the head unit 32, as shown in FIG. 2, the recording head array 30 moves upward, and the maintenance unit 34 moves into the gap formed between the conveyance belt 28 and enters. . Then, a predetermined maintenance operation (vacuum, dummy jet, wiping, capping, etc.) is performed in a state of facing the nozzle surface 33N (see FIGS. 3 and 7) which is a discharge surface.

  In the present embodiment, the four maintenance units 34 are divided into two sets of two, and the recording head array 30 is arranged on the upstream side in the transport direction and the downstream side in the transport direction of the recording head array 30 during image recording. I am doing so.

  As shown in detail in FIG. 3, a charging roll 36 to which a power source 38 is connected is disposed on the upstream side in the transport direction of the recording head array 30. The charging roll 36 is driven while sandwiching the conveyance belt 28 and the paper P with the driven roll 26, and moves between a pressing position for pressing the paper P against the conveyance belt 28 and a separation position separated from the conveyance belt 28. It is possible. At the pressing position, a predetermined potential difference is generated between the grounded driven roll 26 and the sheet P can be charged and electrostatically attracted to the transport belt 28.

As the charging roll 36, for example, a roll having a diameter of 14 mm can be used in which conductive rubber is coated on the surface of silicone rubber and the volume resistance value is adjusted to about 10 ⁶ to 10 ⁷ Ω · cm.

  As the power source 38, a DC power source is shown in FIG. 3, but an AC power source may be used as long as the paper P can be charged to a predetermined potential.

  A registration roll (not shown) is provided further on the upstream side in the transport direction than the charging roll 36, and the paper P is aligned before reaching between the transport belt 28 and the charging roll 36.

  A peeling plate 40 (see FIGS. 1 and 2) is disposed on the downstream side in the transport direction of the recording head array 30, and the paper P can be peeled from the transport belt 28. As the peeling plate 40, for example, an aluminum plate having a thickness of 0.5 mm, a width of 330 mm, and a length of 100 mm can be used.

  The peeled paper P is transported by a plurality of rotatable discharge roller pairs 42 constituting a discharge path 44 on the downstream side in the transport direction of the peeling plate 40, and is discharged to a paper discharge tray 46 provided at the upper part of the housing 14. Discharged.

  Below the peeling plate 40, a cleaning roll 48 is disposed so that the conveyance belt 28 can be sandwiched between the drive roll 24 and the surface of the conveyance belt 28 is cleaned.

  A reversing path 52 including a plurality of reversing roller pairs 50 is provided as a reversing unit between the paper feed tray 16 and the conveying belt 28, and the sheet P on which an image is recorded on one side is reversed and conveyed. By holding the belt 28, image recording on both sides of the paper P can be easily performed.

  Between the transport belt 28 and the paper discharge tray 46, there are provided an ink tank 54 for storing each of the four color inks, and a reservoir tank 64 connected to the downstream side of the ink tank 54. The reservoir tank 64 is provided with an air release portion 65, and the liquid level in the reservoir tank 64 is at atmospheric pressure. The ink in the reservoir tank 64 is supplied to each head unit 32 via a first ink line 69 and a second ink line 70 which will be described later. As the ink, various known inks such as water-based ink, oil-based ink, and solvent-based ink can be used.

  As shown in FIG. 4, the entire inkjet recording apparatus 12 is controlled by a controller 56, and operations including image recording, discharging, and maintenance are performed from taking out the paper P. Various data relating to the recorded image is sent from the image controller 58 to the controller 56. For example, as will be described later, the applied voltage and the like in the first charging mode and the second charging mode are controlled by the controller 56 in accordance with the data of the recorded image. The inkjet recording head 33 is controlled by a head controller 60, and a signal is transmitted from the controller 56 to the head controller 60. The controller 56, the head controller 60, and the charging roll 36 are supplied with power from a power source 38.

  In the ink jet recording apparatus 12 of the present embodiment configured as described above, the paper P taken out from the paper feed tray 16 is transported to the transport belt 28 as described above. Then, it is pressed against the conveyor belt 28 by the charging roll 36 and is held by being attracted (contacted) to the conveyor belt 28 by the voltage applied from the charging roll 36. In this state, while the paper P passes through the ejection area SE by circulation of the transport belt, ink droplets are ejected from the recording head array 30 and an image is recorded on the paper P. When recording an image in only one pass, the sheet P is peeled off from the transport belt 28 by the peeling plate 40, transported by the discharge roller pair 42, and discharged to the paper discharge tray 46. On the other hand, when performing image recording by multi-pass, after the paper P is circulated until it reaches the required number of times and passed through the ejection region SE, the paper P is peeled off from the transport belt 28 by the peeling plate 40, The paper is conveyed by the discharge roller pair 42 and discharged to the paper discharge tray 46.

(Ink flow line)
Hereinafter, one color (for example, yellow) will be described with respect to ink flow, and the other colors have the same configuration and function, and thus description thereof will be omitted.

  As shown in FIGS. 5 and 6, the ink jet recording head 33 is formed with an ink chamber 72 and a discharge nozzle 73 (see FIG. 7) communicating with each ink chamber 72. Ink droplets are ejected from the ejection nozzle 73 by increasing the pressure. That is, as shown in FIG. 7, the lower surface side of the inkjet recording head 33 is a discharge surface, and 1024 discharge nozzles 73 are arranged.

  The ink jet recording apparatus 12 is provided with a first ink line 69 and a second ink line 70 that connect the ink chamber 72 and the reservoir tank 64.

  The reservoir tank 64 is provided with a filter portion 66 so as to divide the reservoir tank 64 into two upper and lower chambers. The filter portion 66 allows a lower downstream chamber 64L to which the first ink line 69 is connected, The upper upstream chamber 64U to which the second ink line 70 is connected is divided. A tank connection line 55 that connects the reservoir tank 64 and the ink tank 54 is provided with a feed pump 57 for feeding the ink liquid in the ink tank 54 toward the reservoir tank 64.

  The second ink line 70 is provided with a pump 74 and a bypass line 78 that bypasses the pump 74 so that the ink flow direction can be switched. An open / close valve 76 is provided in the bypass line 78.

  The pump 74 is provided so as to apply a fluid force from the ink chamber 72 to the reservoir tank 64 to the ink liquid. The ink jet recording apparatus 12 is provided with a motor (not shown) for driving the pump 74, and this motor is controlled by the controller 56. The controller 56 also controls the opening / closing of the on / off valve 76.

  The second ink line 70 is provided with a three-way valve 80 closer to the reservoir tank 64 than the bypass line 78. A branch pipe 82 connected to the downstream chamber 64L is connected to the three-way valve 80.

  As shown in FIG. 8, the maintenance unit 34 includes a cap 88 that receives ink from the nozzle surface 33 </ b> N and a drain line 92 that discharges ink received by the cap 88 during the recovery operation of the inkjet recording apparatus 12. Yes. A waste ink tank 96 is provided through a valve 94 at the downstream end of the ink flow in the drainage line 92. Further, the ink jet recording apparatus 12 includes a second pump 98 (a pump for recovery operation of the ink jet recording head 33) 98 that gives ink delivery force (ink suction force) from the cap 88 to the drainage line 92, and a second pump 98. A motor to be driven (not shown). This motor is controlled by the controller 56 in the same manner as the motor that drives the pump 74.

  At the time of ink discharge, as shown in FIG. 5, the pump 74 is stopped, the on-off valve 76 is opened, the connection to the upstream chamber 64U is blocked by the three-way valve 80, and the branch pipe 82 and the three-way valve 80 are disconnected. The second ink line portion 70I up to the ink jet recording head 33 is connected. Then, the ink chamber 72 is depressurized by the ejection of the ink droplets, and the capillary force acts on the ejection nozzle portion, so that the first ink line 69, the branch pipe 82, and the second ink line portion 70I are all downstream. The ink liquid flows from the chamber 64L to the ink chamber 72. Accordingly, the ink liquid supplied to the ink chamber 72 when ink is ejected is the ink liquid after being filtered by the filter unit 66, and foreign matters such as dust are removed. In addition, since the ink liquid flows into the ink chamber 72 from the two ink lines, the ink liquid can be supplied efficiently. The pressure loss is greatly reduced as compared with the case where there is one ink line, and the allowable pressure loss value for each ink line can be set to about twice, so that the cross-sectional area of the supply path can be reduced. Accordingly, it is possible to reduce the volume of the piping, and further reduce the size and cost of the apparatus. Furthermore, since the flow rate becomes faster and the pump 74 does not require excessive performance, the pump 74 can be downsized.

  At the time of ink circulation, as shown in FIG. 6, the pump 74 is driven to close the on-off valve 76 and the connection to the branch pipe 82 is cut off by the three-way valve 80, and the upstream side of the second ink line 70 Connect to the downstream side. In the first ink line 69, the ink liquid flows from the downstream chamber 64L to the ink chamber 72. In the second ink line 70, the ink liquid flows from the ink chamber 72 to the upstream chamber 64U, and the ink liquid circulates. Accordingly, the ink can be circulated by using the second ink line 70 in which the ink liquid is allowed to flow into the ink chamber 72 when ink is ejected. By this ink circulation, bubbles in the ink liquid can be discharged in the reservoir tank 64, and further discharged from the atmosphere opening section 65 to the atmosphere, and dust in the ink liquid can be removed by the filter section 66. . That is, dust and bubbles can be removed without going through the discharge nozzle 73.

  Further, since the pump 74 is provided in the second ink line 70, a suction force acts on the ink chamber 72. Therefore, compared with the case where the ink liquid is pumped and circulated through the ink jet recording head, ink leakage due to the application of pressure does not occur from the connection portion or joint portion of the flow path or the discharge nozzle.

  In addition, the ink flow direction of the second ink line 70 can be switched with a simple configuration of the pump 74 and the on-off valve 76.

  9 and 10, instead of the reservoir tank 64, a filter unit 106 and a normal reservoir tank 104 connected downstream thereof may be provided. In the filter unit 106, the tank connection line 55 and the second ink line 70 are connected to the upstream side (ink inflow side), and the connection pipe 108 connected to the reservoir tank 104 is connected to the downstream side (ink outflow side). . As a result, the same effect can be obtained even in a configuration using the normal reservoir tank 104 and the filter unit 106.

[Second Embodiment]
Next, a second embodiment will be described. As shown in FIGS. 11 to 13, the ink jet recording apparatus according to this embodiment has a first configuration similar to that of the second ink line 70 instead of the first ink line 69 as compared to the first embodiment. An ink line 119 is provided. As a result, the direction of ink flow during ink circulation can be switched between the direction of flowing from the first ink line 119 to the upstream chamber 64U and the direction of flowing from the second ink line 70 to the upstream chamber 64U.

  The first ink line 119 is provided with a pump 123 and a bypass line 127 that bypasses the pump 123 so that the ink flow direction can be switched. The bypass line 127 is provided with an on-off valve 125.

  The pump 123 is provided so as to apply a fluid force from the ink chamber 72 to the reservoir tank 64 to the ink liquid. The ink jet recording apparatus according to the present embodiment is provided with a motor (not shown) for driving the pump 123, and this motor is controlled by the controller 56. The controller 56 also controls the opening / closing of the opening / closing valve 125.

  The first ink line 119 is provided with a three-way valve 129 closer to the reservoir tank 64 than the bypass line 127. A branch pipe 131 connected to the upstream chamber 64U is connected to the three-way valve 129.

  At the time of ink ejection, as shown in FIG. 11, the operation of the second ink line 70 is the same as the operation of the second ink line 70 described in the first embodiment. The operation of the first ink line 119 is the same as that of the second ink line 70. The pump 123 is stopped, the on-off valve 125 is opened, the connection to the branch pipe 131 is cut off by the three-way valve 129, and the first ink line The upstream side and the downstream side of the line 119 are connected.

  At the time of ink circulation, (1) as shown in FIG. 12, when the ink liquid is circulated from the second ink line 70 to the upstream chamber 64U, the operation of the second ink line 70 is the same as in the first embodiment. It is. For the first ink line 119, the pump 123 is stopped, the on-off valve 125 is opened, the connection to the upstream chamber 64U is blocked by the three-way valve 129, and the upstream side and the downstream side of the second ink line 70 are disconnected. Connecting. As a result, the ink chamber 72 and the downstream chamber 64L communicate with each other in the first ink line 119, and the ink liquid flows from the downstream chamber 64L to the ink chamber 72 in the first ink line 119 by driving the pump 74.

  (2) As shown in FIG. 13, when the ink is circulated in the direction in which the ink liquid flows from the first ink line 119 to the upstream chamber 64U, the case of the above (1) in the first ink line 119 and the second ink line 70. Perform the reverse operation.

  According to the present embodiment, during ink circulation, the ink flow direction can be switched between a direction in which the ink flows from the first ink line 119 into the reservoir tank 64 and a direction in which the ink flows from the second ink line 70 into the reservoir tank 64. is there. Therefore, it is easier to remove foreign matters such as dust and bubbles in the ink liquid.

  The pump 74 may be a pump that can rotate in both forward and reverse directions, and the line connecting the three-way valve 129 and the inkjet recording head 33 by removing the pump 123 and the on-off valve 125 may be a single line. Thereby, even with a simpler configuration, the direction of ink flow during ink circulation can be switched.

[Third Embodiment]
Next, a third embodiment will be described. As shown in FIGS. 14 and 15, in the ink jet recording apparatus according to this embodiment, the configuration of the second ink line is different from that of the first embodiment. The second ink line 140 connecting the inkjet recording head 33 and the reservoir tank 64 is provided with a three-way communication portion 150 in which three lines communicate with each other in place of the three-way valve 80, and the three-way communication portion 150. One-way valves 154 and 156 are provided in the line connecting the upstream chamber 64U and the branch pipe 80, respectively. In the one-way valve 154, the ink liquid flows only from the three-way communication part 150 to the upstream chamber 64U, and in the one-way valve 156, the ink liquid flows only from the downstream chamber 64L to the three-way communication part 150.

  According to this embodiment, it is not necessary to perform a switching operation of the three-way valve as compared with the first embodiment.

[Fourth Embodiment]
Next, a fourth embodiment will be described. As shown in FIGS. 16 to 18, in the ink jet recording apparatus according to the present embodiment, the first ink line 159 is symmetric with the second ink line 140 as compared with the third embodiment. That is, compared to the second embodiment, the first ink line 159 is provided with a three-way communication portion 169 in which three lines communicate with each other instead of the three-way valve 129, and the three-way communication portion 169 and the upstream chamber 64U. One-way valves 163 and 165 are provided in the line connecting the two and the branch pipe 131, respectively. In the one-way valve 163, the ink liquid flows only from the three-way communication portion 169 to the upstream chamber 64U, and in the one-way valve 165, the ink liquid flows only from the downstream chamber 64L to the three-way communication portion 169.

  As a result, the ink circulation direction can be switched between two directions even in an ink jet recording apparatus that does not require a three-way valve switching operation.

  The embodiments of the present invention have been described above with reference to the embodiments. However, these embodiments are merely examples, and various modifications can be made without departing from the scope of the invention. Needless to say, the scope of rights of the present invention is not limited to the above embodiment.

It is a front sectional view showing the configuration of the ink jet recording apparatus of the first embodiment in an image recording state. It is a front sectional view showing the composition of the ink jet recording device of a 1st embodiment in a maintenance state. It is a conceptual diagram which shows the structure of the conveyance belt of the inkjet recording device of 1st Embodiment, and its vicinity. FIG. 2 is a block diagram illustrating a configuration of a control system of the ink jet recording apparatus according to the first embodiment. FIG. 3 is a schematic diagram illustrating an ink flow during ink ejection in the ink jet recording apparatus according to the first embodiment. FIG. 3 is a schematic diagram illustrating an ink flow during ink circulation in the ink jet recording apparatus according to the first embodiment. It is a rear view which shows the structure of the inkjet recording head in 1st Embodiment. It is a schematic diagram which shows the structure of a maintenance unit in 1st Embodiment. FIG. 6 is a schematic diagram illustrating an ink flow when ink is ejected in a modification of the ink jet recording apparatus according to the first embodiment. FIG. 5 is a schematic diagram illustrating an ink flow during ink circulation in a modification of the ink jet recording apparatus according to the first embodiment. It is a schematic diagram which shows the ink flow at the time of ink discharge with the inkjet recording device of 2nd Embodiment. It is a schematic diagram showing an ink flow during ink circulation in the ink jet recording apparatus according to the second embodiment. It is a schematic diagram showing an ink flow during ink circulation in the ink jet recording apparatus according to the second embodiment. It is a schematic diagram which shows the ink flow at the time of ink discharge in the inkjet recording device of 3rd Embodiment. It is a schematic diagram which shows the ink flow at the time of ink circulation in the inkjet recording device of 3rd Embodiment. It is a schematic diagram which shows the ink flow at the time of ink discharge in the inkjet recording device of 4th Embodiment. It is a schematic diagram which shows the ink flow at the time of ink circulation in the inkjet recording device of 4th Embodiment. It is a schematic diagram which shows the ink flow at the time of ink circulation in the inkjet recording device of 4th Embodiment. It is a block diagram of an example of the conventional inkjet recording device.

Explanation of symbols

12 Inkjet recording device (droplet ejection device)
33 Inkjet recording head (droplet ejection head)
64 Reservoir tank (tank)
64L Downstream chamber 64U Upstream chamber 66 Filter section 69 First ink line (first line)
70 Second ink line (second line)
72 Ink chamber 73 Discharge nozzle 74 Pump 76 On-off valve 78 Bypass line 80 Three-way valve 82 Branch pipe 104 Reservoir tank 106 Filter unit 119 First ink line (first line)

Claims (3)

A liquid discharge head for forming a liquid chamber and a discharge nozzle communicating with the liquid chamber and discharging liquid droplets from the discharge nozzle;
A tank storing liquid,
A filter unit provided in the tank, which divides the tank into a downstream chamber and an upstream chamber and through which a liquid passes;
A first line connecting the liquid chamber and the downstream chamber ;
A second line connecting the liquid chamber and the upstream chamber ;
With
Wherein the second line, and a pump for flowing the liquid toward the tank from the liquid chamber, a bypass line opening and closing valve is provided with bypassing said pump, said at the upstream chamber side of said bypass line A branch pipe branched from the second line and connected to the downstream chamber, and a three-way valve provided at a branch point between the branch pipe and the second line,
At the time of discharging a droplet, the pump is stopped and the on-off valve is opened, and the connection between the second line and the upstream chamber is interrupted by the three-way valve, and the second line and the branch pipe And supplying liquid from the downstream chamber to the liquid chamber through the first line and supplying liquid from the downstream chamber to the liquid chamber through the branch pipe and the second line,
During the circulation of the liquid, the pump is driven and the on-off valve is closed , and the three-way valve connects the second line and the upstream chamber and connects the second line and the branch pipe. blocking to the liquid stored in the upstream chamber, the downstream chamber, the first line, the liquid chamber, and a droplet discharge device, characterized in that circulating into the upstream chamber through the second line. The droplet discharge device according to claim 1, wherein the rotation direction of the pump is switchable . The liquid droplet ejection apparatus according to claim 1, wherein image formation is performed using an ink liquid as a liquid.

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