JP2012096510A - Fluid storage tank, fluid ejecting head unit and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that an air bubble is not efficiently discharged from a filter upstream chamber in a head tank.SOLUTION: An ink storage unit 22 of the head tank 4 is divided into the upstream chamber 35 and a down stream chamber 36 by a filter member 207 disposed in a direction along a droplet ejecting direction, and includes a first flow passage 27 for feeding ink to the upstream chamber 35 from the outside and a second flow passage 28 for discharging ink or gas to the outside from the upstream chamber 35 of the storage unit 22. The storage unit 22 includes a top surface 22a inclined in a height direction, wherein an opening 28a lead to the upstream chamber 35 of the second flow passage 28 is provided in the highest position in the height direction of the inclined top surface 22a and also the opening 28a lead to the upstream chamber 35 of the second flow passage 28 and an opening 27a lead to the upstream chamber 35 of the first flow passage 27 are provided in positions that are separated farthest from each other in the same wall surface (top surface 22a).

Description

  The present invention relates to a liquid storage tank, a liquid discharge head unit, and an image forming apparatus.

  As an image forming apparatus such as a printer, a facsimile, a copying machine, a plotter, or a complex machine of these, for example, a liquid discharge recording type image forming using a recording head composed of a liquid discharge head (droplet discharge head) that discharges ink droplets. As an apparatus, an ink jet recording apparatus or the like is known. This liquid discharge recording type image forming apparatus means that ink droplets are transported from a recording head (not limited to paper, including OHP, and can be attached to ink droplets and other liquids). Yes, it is also ejected onto a recording medium or a recording medium, recording paper, recording paper, etc.) to form an image (recording, printing, printing, and printing are also used synonymously). And a serial type image forming apparatus that forms an image by ejecting liquid droplets while the recording head moves in the main scanning direction, and a line type head that forms images by ejecting liquid droplets without moving the recording head There are line type image forming apparatuses using

  In the present application, the “image forming apparatus” of the liquid discharge recording method is an apparatus that forms an image by discharging liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, or the like. In addition, “image formation” means not only giving an image having a meaning such as a character or a figure to a medium but also giving an image having no meaning such as a pattern to the medium (simply It also means that a droplet is landed on a medium). “Ink” is not limited to ink, but is used as a general term for all liquids capable of image formation, such as recording liquid, fixing processing liquid, and liquid. DNA samples, resists, pattern materials, resins and the like are also included. In addition, the “image” is not limited to a planar image, and includes an image given to a three-dimensionally formed image and an image formed by three-dimensionally modeling a solid itself.

  In such a liquid ejection type image forming apparatus, a head tank (meaning a tank provided integrally with the head) on the recording head side is used, and in such a tank, a sub tank, a buffer tank, and the like are also used synonymously. ), A main tank is disposed on the apparatus main body side, ink is supplied from the main tank to the sub tank, and ink is supplied from the head tank to the recording head.

  As a head tank, there is known a head tank that includes a filter for filtering impurities, the filter upstream chamber side is connected to a surface tank, and ink is supplied to the recording head from the filter downstream chamber side.

  By the way, if bubbles are mixed in the liquid discharge head, droplet ejection bends and droplet discharge defects occur, and thus it is necessary to efficiently discharge the bubbles in the ink supply path.

  Conventionally, regarding the bubble discharge in the filter upstream chamber of the head tank, a device that sucks and discharges ink together with ink from the nozzle (Patent Document 1), a port that discharges bubbles in the filter upstream chamber and the downstream chamber, respectively (Patent Document 2), There are known ones that discharge a bubble by providing a discharge part in the upper part of the tank and causing ink to overflow from the discharge part (Patent Document 3), and those that provide a reflux path from the head tank to the main tank (Patent Document 4). It has been.

JP 2007-230042 A JP 2007-144976 A JP 2008-173816 A JP 2006-068904 A

  However, in the technique disclosed in Patent Document 1, it is necessary to perform a suction operation in order to discharge bubbles, and accordingly, a cap for sealing the nozzle and a suction means for making the inside of the cap have a negative pressure must be provided. Don't be. Moreover, since bubbles are involved in and discharged from the nozzle, there is a problem that if bubbles remain in the flow path without being discharged from the nozzle, this may cause discharge failure.

  In the technique disclosed in Patent Document 2, although air bubbles remaining in the tank can be discharged without passing through the nozzle by the discharge port, independent flow paths and open / close valves are provided in the upstream chamber and the downstream chamber, respectively. Therefore, there is a problem that the on-demand workability may be deteriorated because the supply system becomes large in size and must be controlled independently.

  In the technique disclosed in Patent Document 3, it is necessary to provide a liquid level detection means inside the tank, and there is a problem that the tank itself is large and complicated, and cannot be downsized.

  In the technique disclosed in Patent Document 4, a large amount of reflux time and the amount of ink to be refluxed are required, which may increase the maintenance time. Further, since bubbles generated in the supply path are captured by the filter and accumulated in the upstream chamber, it is necessary to provide a region for collecting bubbles in the filter upstream chamber, which causes a problem that the tank becomes relatively large.

  The present invention has been made in view of the above-described problems, and an object thereof is to efficiently discharge bubbles from a filter upstream chamber of a head tank.

In order to solve the above problems, the liquid storage tank according to the present invention is:
A liquid storage tank for storing liquid to be supplied to a head for discharging droplets,
An accommodating portion for accommodating a liquid to be supplied to the head;
The accommodating portion is divided into an upstream chamber and a downstream chamber by a filter member,
A first flow path for supplying liquid from outside to the upstream chamber;
A second flow path for discharging the liquid or gas in the upstream chamber to the outside, and
The opening to the upstream chamber of the second flow path is provided at the highest position in the height direction of the upstream chamber,
The opening to the upstream chamber of the second flow path and the opening to the upstream chamber of the first flow path are provided at the farthest positions in the same wall surface.

  Here, the first channel and the second channel may be provided on the top surface of the upstream chamber.

  The opening diameter of the opening of the second flow path is smaller than the opening diameter of the opening of the first flow path, and the fluid resistance of the opening of the second flow path is that the filter member is the liquid. It can be set as the structure smaller than the fluid resistance of the said filter member in the wet state.

  The liquid discharge head unit according to the present invention has a configuration in which a head for discharging droplets and the liquid storage tank according to the present invention are integrated.

  The image forming apparatus according to the present invention includes the liquid storage tank or the liquid discharge head unit according to the present invention.

  According to the liquid storage tank of the present invention, the first flow path for supplying the liquid to the upstream chamber from the outside and the second flow path for discharging the liquid or gas in the upstream chamber to the outside are provided, and the second flow The opening to the upstream chamber of the passage is provided at the highest position in the height direction of the upstream chamber, and the opening to the upstream chamber of the second flow path and the opening to the upstream chamber of the first flow path are the same wall surface. Since the structure is provided at the farthest position in the head, the filter upstream chamber of the head tank at the time of initial filling (first filling to the empty state or filling of the required liquid from the state of filling the filling liquid) Air bubbles can be efficiently discharged from.

  According to the liquid discharge head unit according to the present invention, the head and the liquid storage tank according to the present invention are integrated, so that bubbles can be efficiently discharged from the filter upstream chamber of the head tank.

  According to the image forming apparatus of the present invention, since the liquid storage tank or the liquid discharge head unit according to the present invention is provided, an image can be formed by performing stable droplet discharge.

It is explanatory drawing of the ink supply system containing the liquid discharge head unit which shows 1st Embodiment of this invention. It is typical cross-sectional explanatory drawing which follows the AA line of FIG. It is typical cross-sectional explanatory drawing which follows the BB line of FIG. FIG. 6 is a schematic front proof diagram for explaining an ink initial filling operation for the liquid ejection head unit. It is a typical front explanatory drawing similarly. FIG. 3 is a schematic cross-sectional explanatory view similar to FIG. 2. It is a typical front explanatory drawing similarly. FIG. 3 is a schematic cross-sectional explanatory view similar to FIG. 2. It is a typical front explanatory drawing similarly. FIG. 4 is a schematic cross-sectional explanatory view similar to FIG. 3. It is a typical front explanatory drawing similarly. It is a typical front explanatory drawing similarly. FIG. 6 is a schematic front proof diagram for explaining a droplet discharge state from the liquid discharge head unit. FIG. 6 is a schematic front explanatory view of a liquid discharge head unit showing a second embodiment of the present invention. It is typical front explanatory drawing with which it uses for description of the flow of air when wash | cleaning with a washing | cleaning liquid. 1 is a schematic explanatory diagram for explaining an example of an overall configuration of an image forming apparatus according to the present invention.

Embodiments of the present invention will be described below with reference to the accompanying drawings. An image forming apparatus according to a first embodiment of the present invention will be described with reference to FIGS. 1 is an explanatory diagram of an ink supply system of the image forming apparatus according to the embodiment, FIG. 2 is an explanatory sectional view of the head tank along the line AA in FIG. 1, and FIG. 3 is along the line BB in FIG. FIG.
A liquid discharge head unit (hereinafter also simply referred to as “head unit”) 1 includes a head 2 that discharges droplets and a liquid storage tank that stores ink to be supplied to the head 2 (hereinafter referred to as “head tank”). 4 is provided.

  The head 2 is supplied with ink to a plurality of nozzles 11 that discharge droplets, a liquid chamber 12 that communicates with each nozzle 11, a common liquid chamber 13 that supplies ink to each liquid chamber 12, and a common liquid chamber 13. A supply port (ink supply port) 14 and a discharge port (ink discharge port) 15 for discharging ink from the common liquid chamber 13.

  The head tank 4 includes an ink storage portion 22 that stores ink to be supplied to the head 2 in a tank case 21, a supply port 24 that supplies ink from the ink storage portion 22 to the supply port 14 of the head 2, and a discharge port of the head 2. A discharge passage 25 for discharging the ink discharged from the outlet 15 to a third flow path (discharge flow path) 39, and the ink container 22 is a filter for filtering impurities in the ink arranged in the vertical direction. 207 is divided into a filter upstream chamber (hereinafter simply referred to as “upstream chamber”) 35 and a filter downstream chamber 36. A filter downstream chamber (hereinafter simply referred to as “downstream chamber”) 36 communicates with a supply path 203 that communicates with the supply port 24 via a communication path 204.

  In the tank case 21, the first flow path (ink supply flow path port) 27 for supplying ink from the outside to the upstream chamber 35 of the storage section 22 and the ink or gas from the upstream chamber 35 of the storage section 22 to the outside A second flow path (bubble discharge path) 28 for discharging is provided.

  Here, the accommodating portion 22 has a top surface 22a inclined in the height direction, and the opening 28a to the upstream chamber 35 of the second flow path 28 is the highest position in the height direction of the inclined top surface 22a, That is, it is provided at the highest position in the height direction of the upstream chamber 35, and the opening 28a of the second flow path 28 to the upstream chamber 35 and the opening 27a of the first flow path 27 to the upstream chamber 35 are the same. It is provided in the most distant position in the wall surface (top surface 22a).

  The tank case 21 of the head tank 4 is a member that is open on one side, and a film member 23 (shown with shading in FIG. 1) as a flexible elastically deformable member in the opening. Is attached to absorb pressure fluctuations.

  On the other hand, a replaceable main tank (ink cartridge) 5 is disposed on the apparatus main body side to supply and replenish ink to the head tank 4. The ink tank 5 is provided with a joint (not shown) with a valve at the tip, and is detachable from the ink supply path 51 and the ink return path 53. The main tank 5 can be easily replaced from the joint. It is like that.

  Then, the ink is supplied from the main tank 5 to the first flow path 27 of the head tank 4 by the ink supply pump 52 through the ink supply path 51. The discharge path 25 of the head tank 4 is connected to the main tank 5 via an ink return path 53, and an open / close valve (valve) 54 is interposed in the ink return path 53. An on-off valve (valve) 55 is also interposed in the second flow path 28 of the head tank 4.

  In addition, the main tank 5 is provided with an air release pipe 56 for preventing the ink in the tank 5 from being exposed to the outside air for a long time and drying or solidifying. The flow path of the air release pipe 56 has an elongated tubular shape, and the humidity in the pipe changes along its length, so that it is possible to prevent the ink in the main tank 5 from coming into direct contact with the outside air. It is possible to prevent the ink from drying or thickening or coagulating.

Next, the flow of ink filling to the liquid discharge head unit will be described with reference to FIGS.
First, as shown in FIG. 4, the ink 300 is supplied from the first flow path 27 to the upstream chamber 35 of the accommodating portion 22 of the head tank 4. At this time, the filter 207 gets wet with the ink 300, so that the air does not permeate, and the air in the upstream chamber 25 is exhausted from the second flow path 28 to the outside of the head tank 4. The on-off valve 55 is open.

  As shown in FIGS. 5 and 6, when the upstream chamber 35 is filled with ink, the air in the upstream chamber 35 is discharged from the second flow path 28 to the outside of the head tank 4. Here, since the opening 28a of the second flow path 28 is provided at the highest position in the space of the upstream chamber 35 on the top surface 22a of the upstream chamber 35, the ink 300 filled in the upstream chamber 35 is the first. Since air is pushed out toward the two flow paths 28, there is no residual air in the upstream chamber 35 and the ink 300 is filled.

  Thereafter, as shown in FIG. 7, the on-off valve 55 of the second flow path 28 is closed. By closing the on-off valve 55, the pressure in the upstream chamber 35 increases, and the ink 300 flows through the filter 207 to the downstream chamber 36 as shown in FIG. At this time, the resistance applied to the opening 28a of the second flow path 28 must be lower than the resistance when air passes through the wet filter 207.

  Next, the ink passes through the filter 207 and flows into the supply path 203 from the opening 204 of the downstream chamber 36 as shown in FIGS. 9 and 10. At this time, the air in the downstream chamber 36 is sent to the common flow path 13 side of the head 2 and discharged through the discharge path 25 described later.

  Thereafter, as shown in FIG. 11, the discharge path 25 ink from the head 2 to the head tank 4 is filled.

  Further, as shown in FIG. 12, the ink 300 filled in the discharge path 25 of the head tank 4 is returned to the ink tank 5 through the return channel 53. Then, after the ink 300 is filled in at least the return passage 51 upstream of the opening / closing valve 54 of the head 2, the head tank 4 and the return passage 53, the opening / closing valve 54 is closed as shown in FIG. The ink filling operation is completed.

  Thereafter, as shown in FIG. 13, an image can be formed by discharging droplets 301 from the nozzles 11 of the head 2.

  As described above, the first flow path for supplying the liquid from the outside to the upstream chamber of the filter of the head tank and the second flow path for discharging the liquid or gas in the upstream chamber to the outside are provided, and upstream of the second flow path. The opening to the chamber is provided at the highest position in the height direction of the upstream chamber, and the opening to the upstream chamber of the second flow path and the opening to the upstream chamber of the first flow path are the most in the same wall surface. By adopting a configuration provided at a distant position, air bubbles can be efficiently discharged from the filter upstream chamber of the head tank.

Next, a head tank according to a second embodiment of the present invention will be described with reference to FIG.
In the present embodiment, a communication path 37 that communicates the downstream chamber 36 and the discharge path 25 is provided.

  Thereby, when the downstream chamber 36 of the head tank 4 is filled with ink, the air in the downstream chamber 36 can be discharged to the discharge path 25 to reduce the inflow of air into the flow path in the head 2. can do.

  In the head tank of each of the embodiments described above, in the case of liquid replacement (in which the filling liquid previously filled in the head tank is replaced with ink by initial filling), in the case where the inside of the head tank is washed with a cleaning liquid, as shown in FIG. By providing the second flow path 28 at the position farthest from the first flow path 27 on the top surface 22a, the air flow in the head tank 4 circulates as shown by the arrow 40, so there is no stagnation (stagnation) and efficient. Can be cleaned. Further, a supply port for a liquid (for example, a cleaning liquid) used for cleaning can be performed using the second channel 28 instead of the first channel 27, or both.

Next, an example of an image forming apparatus including the liquid discharge head unit described in each of the above embodiments will be described with reference to FIG.
In this image forming apparatus, a recording head 101 composed of the liquid discharge head unit 1 is mounted on a carriage 103, and is slid by a main guide rod 104 and a sub guide member (not shown) that are horizontally mounted between the left and right side plates 100A and 100B. Supports freely. The recording head 101 is moved and scanned in the main scanning direction by the main scanning motor 106 via the timing belt 105. On the other hand, the recording medium 107 is opposed to the nozzle surface 11a of the recording head 101, and is conveyed by the conveying roller 109 in a direction orthogonal to the moving direction of the recording head 101, and ink droplets ejected from the recording head 101 according to the image. An image is formed by adhesion.

  Ink is supplied to the recording head 101 from the main tank unit 102 in which the main tank 5, the atmosphere release pipe 56, and the like are accommodated via the ink supply pump 52 through the flexible ink supply path 51. Ink that has not been ejected or discharged from the nozzles is returned to the main tank unit 102 through the ink return path 53.

  The cap member 111 provided outside the recording area is made of an elastic body, preferably silicon rubber, for capping the nozzle surface 108 having the plurality of nozzles 11. At the time of non-recording, the recording head 101 moves to above the cap member 111, and the cap member 111 moves by a cap moving mechanism (not shown) to cap the nozzle surface 108. In the cap member 111, an ink absorbing sheet 112 is provided for facilitating suction during ink suction, moistening the atmosphere in the cap, and the like.

  Two tubes 113, 114 are connected to the cap member 111 on the bottom surface, and the tube 113 communicates with the atmosphere via the atmosphere release valve 115. The tube 114 is connected to the suction pump 116, and the nozzle surface 108 is capped by the cap member 111, and the suction pump 116 is driven to generate a negative pressure in the cap member 111 with the atmosphere release valve 115 closed. Then, ink is sucked from the nozzles of the recording head 101 and the air release valve 115 is opened to discharge the ink accumulated in the space 117 in the cap member 111 to the waste liquid tank 118. Further, the cap member 111 prevents the nozzles of the recording head 101 from drying by contacting and holding the nozzle surface 108 with the atmosphere release valve 115 closed.

  Further, a wiper blade (wiper member) 119 is moved to a height at which it contacts the nozzle surface 108 of the recording head 101 by a wiper moving mechanism (not shown), and the recording head 101 is moved in the main scanning direction. The ink and dust adhering to 108 can be wiped off, and the meniscus on the nozzle surface 108 can be generated and cleaned.

  In the above-described embodiment, an example in which the present invention is applied to a serial type image forming apparatus has been described. However, the present invention can be similarly applied to a line type image forming apparatus.

DESCRIPTION OF SYMBOLS 1 Liquid discharge head unit 2 Head 4 Head tank 5 Main tank 11 Nozzle 13 Common liquid chamber 14 Supply port 15 Discharge port 21 Tank case 22 Ink storage part 23 Damper member (film member)
24 supply port 25 discharge path 35 filter upstream chamber 36 filter downstream chamber 51 ink supply path 52 ink supply pump 53 ink return flow path 101 recording head (liquid discharge head unit)

Claims (5)

A liquid storage tank for storing liquid to be supplied to a head for discharging droplets,
An accommodating portion for accommodating a liquid to be supplied to the head;
The accommodating portion is divided into an upstream chamber and a downstream chamber by a filter member,
A first flow path for supplying liquid from outside to the upstream chamber;
A second flow path for discharging the liquid or gas in the upstream chamber to the outside, and
The opening to the upstream chamber of the second flow path is provided at the highest position in the height direction of the upstream chamber,
The liquid storage tank, wherein the opening to the upstream chamber of the second flow path and the opening to the upstream chamber of the first flow path are provided at the farthest positions within the same wall surface.   The liquid storage tank according to claim 1, wherein the first flow path and the second flow path are provided on a top surface of the upstream chamber.   The opening diameter of the opening of the second flow path is smaller than the opening diameter of the opening of the first flow path, and the fluid resistance of the opening of the second flow path is such that the filter member is wet with the liquid. A liquid storage tank having a smaller fluid resistance than that of the filter member in a state.   4. A liquid discharge head unit comprising a head for discharging liquid droplets and the liquid storage tank according to claim 1.   An image forming apparatus comprising the liquid tank according to claim 1 or the liquid discharge head unit according to claim 4.

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