JP2010214845A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus maintaining each of a damper function and gas barrier performance in a distribution tank at a high level and preventing separation of two types of sheet members. <P>SOLUTION: An elastic sheet 41 and a resin film 42 are provided over an approximately overall wall face (side plate 38) of the distribution tank 21. Since a damper includes the two layers which are the elastic sheet 41 and the resin film 42, the damper function and gas barrier performance can be obtained at a high level. The elastic sheet 41 and the resin film 42 are bonded or welded to projections 38b of the side plate 38, and nipped between the side plate 38 and a tank body 37. Thus, the elastic sheet 41 and the resin film 42 can be securely fixed to the distribution tank 21. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a line ink jet type image forming apparatus.

  The line engine in the line inkjet type image forming apparatus is an engine that forms a line by arranging recording heads over almost the entire width of the recording medium and simultaneously ejecting ink. In a distribution tank (= distributor, distributor) that supplies ink to a plurality of recording heads of the line engine, in order to prevent image unevenness, the pressure fluctuation of the ink in the distribution tank is suppressed, and the ink in the distribution tank is In order to prevent an increase in the amount of dissolved oxygen, two functions of a high gas barrier property of the distribution tank are required.

  Generally, it is known to provide a pressure fluctuation absorbing means using a flexible film for absorbing a pressure change (vibration during ejection, external vibration, mechanical vibration) in the ink supply path to the recording head. ing. It is considered that it is desirable to absorb the pressure change closer to the recording head, and the distribution tank is provided with a flexible member (damper).

  In addition to a distribution tank, a member that supplies ink to a recording head generally requires high gas barrier properties. This is because the discharge nozzles of the recording head are very fine, and if the amount of dissolved oxygen in the discharge ink is high, oxygen gradually accumulates and ink discharge failure may occur.

  Japanese Patent Application Laid-Open No. 2004-237666 (Patent Document 1) discloses a damper that can reliably reduce pressure fluctuations in a liquid supply system without causing a decrease in pressure absorption performance or gas barrier performance due to a change in external environment such as humidity. For the purpose of providing, the damper mainly includes a base, a filter, a leaf spring, and a flexible film as a pressure absorbing film. The flexible film includes a three-layer film. The moisture barrier material such as polyethylene is used for the inner layer and the outer layer, and the intermediate layer sandwiched between the inner layer and the outer layer is formed of a gas barrier material such as ethylene vinyl alcohol copolymer or nylon. Is disclosed.

  Japanese Patent Laid-Open No. 2001-199077 (Patent Document 2) discloses a movable object connected to the tip of a liquid supply tube connected to a fixed liquid tank for the purpose of further improving the pressure fluctuation attenuation effect and reducing the size. A pressure fluctuation suppressing device for supplying liquid to a liquid chamber provided in the housing, having a housing having a pressure damper chamber for storing liquid, an inflow opening above the liquid surface of the pressure damper chamber, and a liquid supply tube Disclosed is a pressure fluctuation suppressing device comprising: an inflow port connected; an outflow port connected to a liquid chamber provided at a lower portion of one side surface of the housing; and a flexible film covering the pressure damper chamber. Has been.

  Japanese Patent Laid-Open No. 2008-143027 (Patent Document 3) discloses the use of a plurality of flexible members and a structure in which a damping material is applied to the members in order to reliably suppress pressure fluctuations. .

  However, when two types of sheet members are used in order to improve the gas barrier property, if the adhesive force is weak, the ink may be peeled off and the ink may leak, and the pressure fluctuation is suppressed and the gas barrier property is maintained at a high level. There was a problem that could not.

  The present invention solves the above-described problems in the conventional image forming apparatus, and provides a line ink jet type image forming apparatus capable of maintaining the damper function and the gas barrier property in the distribution tank of the ink jet engine at a high level. Let it be an issue.

  According to the present invention, there is provided an image forming apparatus including a plurality of droplet discharge heads for discharging droplets, the image forming apparatus including a distribution tank that distributes liquid to each of the plurality of droplet discharge heads. The tank has an opening at least one of the wall surfaces constituting the distribution tank, and has a damper part that elastically deforms according to a pressure change in the distribution tank so as to close the opening, and the damper part is elastically deformed It is formed of two layers of a possible elastic sheet and a film that is less permeable than the elastic sheet, and the elastic sheet and the film are provided corresponding to substantially the entire surface of the wall surface of the distribution tank, respectively. This is solved by having the film bend away from the elastic sheet.

The elastic sheet is preferably disposed outside the tank of the film.
The elastic sheet is preferably disposed inside the tank of the film.

The elastic sheet and the film are preferably bonded to each other at a substantially central portion.
Further, the elastic sheet and the film are directly bonded or welded to a tank side plate constituting the casing of the distribution tank, and the elastic sheet and the film constitute the casing of the distribution tank and the tank side plate. It is preferable to be sandwiched between tank bodies.

Moreover, it is preferable that the end portion of the elastic sheet and the end portion of the film are bonded or welded to the tank side plate in a state where they are displaced.
Further, the shape of the inner surface of the tank side plate near the bonded or welded portion with the elastic sheet and the film is such that the elastic sheet and the film can follow the tank side plate when the pressure in the tank rises. Preferably, it is configured.

  According to the image forming apparatus of the present invention, each of the damper function and the gas barrier property in the distribution tank can be maintained at a high level by forming the damper portion with a two-layer structure of an elastic sheet and a film having low air permeability. Further, since the film has a portion bent away from the elastic sheet, the film member can cope with expansion and contraction of the elastic sheet, the elastic sheet or the film member is damaged, and the elastic sheet and the film are removed from the tank. It can be prevented from peeling off.

With the configuration of the second aspect, since the film is disposed inside the elastic sheet, it is possible to suppress deterioration of the elastic sheet.
With the configuration of the third aspect, since the elastic sheet is disposed inside the tank of the film, the sealing property of the tank can be improved.

  According to the configuration of the fourth aspect, since the elastic sheet and the film are bonded to each other at substantially the center portion, the negative pressure fluctuation generated in the distribution tank at the time of printing or the like is quickly transmitted to the elastic sheet, and the pressure is quickly transmitted. Can be absorbed.

According to the configuration of the fifth aspect, the elastic sheet and the film can be reliably fixed to the distribution tank, and the elastic sheet and the film can be prevented from peeling off.
According to the configuration of the sixth aspect, the elastic sheet and the film can be securely fixed to the side plate by adhering or welding the elastic sheet and the film to the side plate in a shifted state.

  According to the configuration of the seventh aspect, the elastic sheet and the film can quickly follow the shape of the inner surface of the side plate at the time of pressure maintenance, and good pressure maintenance can be performed.

It is the block diagram seen from the front direction which shows schematic structure in an example of the line-type inkjet image forming apparatus which concerns on this invention. It is a top view of the principal part of the inkjet image forming apparatus. It is a schematic block diagram of an ink supply part. It is sectional drawing of 2 directions which shows the example of the conventional distribution tank. It is sectional drawing of 2 directions which shows another example of the conventional distribution tank. It is sectional drawing of 2 directions which shows 1st Example of a distribution tank, and a head bottom view. It is explanatory drawing which shows the example which has arrange | positioned the elastic sheet inside and the resin film outside. It is sectional drawing of 2 directions which shows 2nd Example of a distribution tank. It is a figure which shows typically the area | region in which an elastic sheet and a resin film are provided, and the bonding part of both. It is a disassembled block diagram for demonstrating attachment of an elastic sheet and a resin film. It is a block diagram for demonstrating the attachment at the time of reverse arrangement | positioning of an elastic sheet and a resin film. It is a figure explaining the structure which improves the responsiveness at the time of pressurization maintenance. It is explanatory drawing at the time of reverse arrangement | positioning of an elastic sheet and a resin film.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram illustrating a schematic configuration of an example of a line-type inkjet image forming apparatus according to the present invention as viewed from the front. FIG. 2 is a plan view of the main part of the inkjet image forming apparatus. This ink jet image forming apparatus is a line type ink jet image forming apparatus in which a head for ejecting liquid droplets from nozzles forms a line configuration over almost the entire width of a recording medium. The present embodiment is an embodiment in a water head difference type apparatus, which may be a serial type or a line type, but in the examples, it will be mainly described as a line type ink jet image forming apparatus.

  The inkjet image forming apparatus includes an apparatus main body 1, a paper feed tray 2 on which recording media P are stacked and fed, a paper ejection tray 3 on which printed recording media are ejected and stacked, and a recording medium ejected from the paper feed tray 2. A transport unit 4 that transports to the tray 3, a head unit 10 that discharges and prints droplets on a recording medium during transport, a cleaning device 5 that cleans the nozzles of the head, and the like.

  The main body of the apparatus is composed of front and rear side plates, stays, and the like (not shown), and the recording media stacked on the paper feed tray 2 are sent to the transport unit 4 one by one by the separation roller 6 and the paper feed roller 7.

  The transport unit 4 includes a transport drive roller 8, a transport driven roller 9, and an endless belt 16, and the endless belt 16 is stretched between the transport drive roller 8 and the transport driven roller 9. A plurality of holes are formed on the surface of the endless belt 16, and a suction fan 17 that sucks the recording medium is disposed below the endless belt 16. By operating the suction fan 17, the recording medium is conveyed while being sucked onto the endless belt. On the conveyance driving roller 8 and the driven roller 9, conveyance guide rollers 18 and 19 are respectively placed on the conveyance driving roller 8 and the driven roller 9 by their own weights guided by guides (not shown). When the conveyance drive roller 8 is rotationally driven by a motor (not shown), the conveyance slave roller 9 and the conveyance guide rollers 18 and 19 are driven to rotate and convey the recording medium. The transport unit 4 is provided so as to be swingable as indicated by a double-pointed arrow B with the transport driven roller 9 as a fulcrum, and is configured to move between a transport position indicated by a solid line and a retracted position indicated by a broken line in the drawing. .

  A head unit 10 that discharges droplets to be printed on a recording medium is disposed above the transport unit 4. The head unit 10 is movable back and forth in the recording medium sheet passing direction (arrow A direction), and slides to the top of the cleaning device 5 during cleaning, which will be described later. The head unit 10 includes a head for ejecting liquid droplets over almost the entire width of the recording medium. Five heads 12 are arranged in each row (head module 11) (heads 12a to 12e). 11 is arranged in four rows (11a to 11d) in a staggered manner. As described later, one head 12 can use two colors. In this example, the head module 11a (heads 12a to 12e) and the head module 11b (heads 12a to 12e) have black (K ) And magenta (M) ink are supplied, and cyan (C) and yellow (Y) ink are supplied to the head module 11c (heads 12a to 12e) and the head module 11d (heads 12a to 12e). As a result, one image line of 150 dpi is formed. However, the head configuration is not limited to this example, and a configuration in which two heads are arranged and one color ink is supplied to each head and the image resolution is increased may be used.

  In the present embodiment, a distribution tank 21 that supplies ink to each head is arranged for each color (distribution tanks 21a to 21d) above the head 12 (head module 11). A sub tank 22 (22a to 22d) is arranged for each color on the upstream side of the distribution tank 21, and the meniscus of the head nozzle is reduced by the water head difference between the sub tank 22 and the head 12 (-20 to -70 mmAq in this example). A negative pressure suitable for holding is maintained.

  In the present embodiment, a pack-type sub tank is employed as the sub tank 22. This is because a flexible pack is used so that the ink and the atmosphere are not in direct contact with each other to prevent an increase in viscosity due to evaporation of water in the ink, and the amount of dissolved oxygen in the ink is kept constant in the head. This is to prevent bubbles from accumulating. The pack-type subtank 22 is covered with a sealed case 24 containing a pack 23, and is connected to a pressurizing pump 25 by a tube. In a maintenance operation performed before printing after being left, maintenance is performed by pressurizing the inside of the sub tank case with the pressure pump 25, sending ink to the head, and discharging ink from the nozzles. This maintenance operation is performed after the head unit 10 moves to the upper part of the cleaning device 5 described later. Further, a main tank 26 (26a to 26d) for storing ink is disposed on the upstream side of the sub tank 22. Both are connected by a supply path using tubes.

  A conveyance guide unit 15 that discharges the recording medium to the sheet discharge tray 3 is formed on the downstream side of the conveyance unit 4. The recording medium conveyed by the conveyance guide unit 15 is discharged to the paper discharge tray 3. The paper discharge tray 3 includes a pair of side fences 31a and 31b that regulate the width direction of the recording medium and an end fence 32 that regulates the leading end of the recording medium.

  A cleaning device 5 for cleaning the nozzle surface of the head is provided below the conveyance guide portion 15. The cleaning device 5 has cleaning means 51 (51a to 51d) corresponding to the respective heads 12, and the cleaning means are arranged in a staggered manner over almost the entire width of the recording medium in the same manner as the heads. Suction pumps 52 (52a to 52d) are arranged below the respective cleaning means 51.

  After printing, when the head that discharges droplets is capped and ink is sucked, or when ink that adheres to the nozzle-nozzle surface of the head is cleaned with a wiper blade (not shown), the transport unit 4 is transported after the printing is stopped. The roller 9 is rotated downward (retracted position) with the fulcrum as a fulcrum to secure a moving space for the head portion. Further, the conveyance guide portion 15 disposed at the upper portion of the cleaning device 5 is also pivoted about the fulcrum 14 in the direction of the arrow C and retracted. After the conveyance unit 4 and the conveyance guide unit 15 are retracted, the head unit 10 moves in the A direction (recording medium sheet passing direction), moves to the upper part of the cleaning device 5 and is fixed, and moves to the cleaning operation of each head. .

FIG. 3 is a schematic configuration diagram of the ink supply unit.
The sub tank 22 and the distribution tank 21 are connected by a supply tube 27 of φ6, and the water head difference between the sub tank 22 and the head 12 is kept at about −20 to −70 mmAq.

  The distribution tank 21 is connected to a waste liquid tank (not shown) via a tube 28, and an electromagnetic valve 29 is provided in the middle of the tube. This is used for air bleeding when initially filling an empty distribution tank, and thereafter when air is accumulated in the distribution tank 21. For this reason, in order to make it easy to remove air, an inclination is provided in the upper part of the inside of the distribution tank, and the tube 28 is connected to a position with a high inclination. The main tank 26 and the sub tank 22 are connected by a φ4 supply tube 33, and an electromagnetic valve 34 is provided in the middle of the supply tube 33.

Here, an example of a conventional distribution tank will be described with reference to FIGS.
A distribution tank is fixed on the head (five in the figure, may be one). A flexible member (damper) installed in the distribution tank for pressure adjustment from external vibration or mechanical vibration is installed on the side surface of the distribution tank. As described above, in the conventional apparatus, since the flexible member is attached to the side surface of the distribution tank only by an adhesive, heat welding, or the like, it is easily peeled off by external vibration, mechanical vibration, or pressurization from the sub tank. 4 shows an example in which the flexible member is provided on substantially the entire side surface of the tank, and FIG. 5 shows an example in which the flexible member is provided on a part of the side surface of the tank.

6A and 6B show a first embodiment of a distribution tank according to the present invention, in which FIG. 6A is a side view of the tank, FIG. 6B is a sectional view of the tank, and FIG.
In FIG. 6, five heads 12 are fixed to the head connecting member 35 by fixing members (screws, adhesives, etc.) not shown. A distribution tank 21 is fixed on the head 12 by a distribution tank fixing member 36. The distribution tank fixing member 36 is a plate spring that is pressed up and down in the figure, and the distribution tank 21 is pressed against the head 12.

  The inside of the distribution tank is divided as shown in FIG. Therefore, two colors can be used with one head. In the case of the head module 11a and the head module 11b described above, black (K) ink is supplied to one side and magenta (M) ink is supplied to the other side. In the case of the head module 11c and the head module 11d, cyan (C) ink is supplied to one side and yellow (Y) ink is supplied to the other side. Reference numeral 39 is a hole communicating with the supply tube 27. Reference numeral 40 denotes an air communication hole.

  (C) The figure shows the lower surface of the head. The head 12 has two rows of nozzle groups 13 and 13. As described above, since two color inks are supplied to one head, black (K) or cyan (C) ink is ejected from one nozzle group (row) 13 and the other nozzle group (row). From 13, magenta (M) or yellow (Y) ink is ejected. As described above, the configuration of the distribution tank and the head is not limited to these examples. The distribution tank is not divided, and one head is filled with one color ink. It is possible to increase the image resolution.

  Now, two sheets of an elastic sheet 41 for relaxing pressure and a gas barrier resin film 42 are adhered and welded to the side plates 38 on both sides of the distribution tank 21. (B) As can be seen from the figure, the elastic sheet 41 and the resin film 42 are not entirely bonded (welded) to the side plate 38, but the peripheral edges of the elastic sheet 41 and the resin film 42 are not bonded. The tank body 37 and the side plate 38 are sandwiched and bonded and welded. A space is formed between the elastic sheet 41 and the resin film 42 and the side plate 38, and the air communication hole 40 is communicated with the space portion. Yes. (A) The code | symbol 38a of a figure shows the area | region in which the elastic sheet 41 and the resin film 42 in the side plate 38 are provided (arranged closely). In the first embodiment, the elastic sheet 41 and A resin film 42 is provided.

As shown in FIG. 7, the elastic sheet 41 and the resin film 42 may be arranged with the elastic sheet 41 inside the tank and the gas barrier resin film 42 outside.
The resin film 42 is made of, for example, a gas barrier material such as ethylene vinyl alcohol copolymer, nylon, or PET. The thickness is about 20 to 70 μm.

The elastic sheet 41 is made of, for example, a natural rubber sheet, EPDM, silicon rubber, nitrile rubber, polyurethane material, or the like. Thickness is about 30-200 μm.
Examples of the attaching method include thermal welding, ultrasonic welding, high-frequency welding, double-sided tape, and epoxy adhesive.

  Here, the resin film 42 is pasted in a state of being slackened in advance so as to cope with the expansion and contraction of the elastic sheet 41. The amount of deflection is preferably about 1 to 5 mm. Thereby, the resin film 42 can respond to the expansion and contraction of the elastic sheet 41, and it is possible to prevent the elastic sheet 41 or the resin film 42 from being damaged and the elastic sheet 41 and the resin film 42 from being peeled off from the tank.

  Conventionally, as shown in FIG. 4 or 5, a single flexible film is attached to the distribution tank. However, in the present invention, as described above, the elastic sheet 41 for pressure relaxation and the gas barrier property are used. Two resin films 42 were used. In this way, by separating the pressure absorption function and the gas barrier function, each function can be enhanced.

  The material of the distribution tank (tank body 37, side plate 38) is preferably the same material as that of the elastic sheet 41 or the resin film 42 from the viewpoint of adhesion, but may be metal or the like.

  FIG. 8 shows a second embodiment of the distribution tank according to the present invention, in which (a) is a side view of the tank and (b) is a cross-sectional view of the tank. Since the bottom view of the head is the same as that of the first embodiment, it is omitted. In addition, the same parts as those in the first embodiment of FIG.

  Also in the second embodiment of FIG. 8, the damper is constituted by two sheets of the elastic sheet 41 for relaxing the pressure and the gas barrier resin film 42. The difference from the first embodiment is the size and shape of the elastic sheet 41 and the resin film 42. That is, in the second embodiment, the elastic sheet 41 and the resin film 42 are disposed on the entire side plate 38 of the distribution tank, as shown by a region 38a in the side plate 38 where the elastic sheet 41 and the resin film 42 are provided in FIG. It is not provided, but is provided on a part of the side surface of the distribution tank (in this example, in a horizontally long rectangular shape). Although not shown in the figure, the pasting area may be divided and provided at several places on the side surface of the distribution tank.

  The material of the elastic sheet 41 and the resin film 42 and the material of the distribution tank (tank body 37, side plate 38) are the same as those in the first embodiment, and the attaching method is also the same. Further, the resin film 42 is attached in a slacked state in advance so as to be able to cope with the expansion and contraction of the elastic sheet 41, and the amount of bending is the same as in the first embodiment.

  FIG. 9 is a side view schematically showing a region where the elastic sheet 41 and the resin film 42 are provided, and a portion where the elastic sheet 41 and the resin film 42 are attached. FIGS. 9A and 9B correspond to the first embodiment of FIG. 6, and FIGS. 9C and 9D correspond to the second embodiment of FIG.

  9A and 9B are provided with an elastic sheet 41 and a resin film 42 corresponding to almost the entire side surface (side plate 38) of the distribution tank 21, and in FIG. 9A, the elastic sheet 41 and the resin film 42 are provided. Are bonded continuously in the horizontal direction at a substantially central portion in the vertical direction. In (b), the elastic sheet 41 and the resin film 42 are bonded in several parts in the horizontal direction at a substantially central portion in the vertical direction. Here, the reason why the adhesive is bonded at the substantially central portion is to quickly transmit the negative pressure fluctuation generated in the distribution tank 21 during printing or the like to the elastic sheet on the outside and to quickly absorb the pressure.

  In (a), the adhesion region at the substantially central portion may be about 2 to 5 mm in width and about 50 to 120 mm in length. In (b), several regions having a width of about 2 to 5 mm and length of about 10 to 30 mm (see FIG. Then there are 3 places). The elastic sheet 41 and the resin film 42 are separated from each other except the adhesion region. Examples of the bonding method include double-sided tape and epoxy adhesive.

  9C and 9D show an elastic sheet 41 and a resin film 42 corresponding to a part of the side surface (side plate 38) of the distribution tank 21, and in FIG. 9C, the elastic sheet 41 and the resin film 42 are provided. Are bonded continuously in the horizontal direction at a substantially central portion in the vertical direction. In (d), the elastic sheet 41 and the resin film 42 are bonded in several parts in the horizontal direction at a substantially central portion in the vertical direction. Here, the reason why the adhesive is bonded at the substantially central portion is to quickly transmit the negative pressure fluctuation generated in the distribution tank 21 during printing or the like to the elastic sheet on the outside and to quickly absorb the pressure.

  In (c), the substantially central bonding region may have a width of about 2 to 5 mm and a length of about 50 to 120 mm. In (d), several regions having a width of about 2 to 5 mm and a length of about 10 to 30 mm (see FIG. Then there are 3 places). The elastic sheet 41 and the resin film 42 are separated from each other except the adhesion region. Examples of the bonding method include double-sided tape and epoxy adhesive.

FIG. 10 is an exploded configuration diagram for explaining attachment of the elastic sheet 41 and the resin film 42.
As described above, the elastic sheet 41 and the resin film 42 have their peripheral ends sandwiched between the tank body 37 and the side plate 38 and bonded and welded together. The elastic sheet 41 and the resin film 42 are bonded to each other at substantially the center.

  More specifically, an elastic sheet 41 for pressure relaxation is bonded and welded to the convex portion 38b of the side plate 38 of the distribution tank 21 (1). Then, the gas barrier resin film 42 is adhered and welded to the convex portion 38b of the side plate 38 in a region that is slightly larger than the elastic sheet 41 (2). In this way, the elastic sheet 41 and the resin film 42 can be securely fixed by being bonded and welded to the side plate 38 in a slightly shifted state.

  Moreover, the substantially center part of the elastic sheet 41 and the resin film 42 is adhere | attached (3). Then, the side plate 38 is bonded and welded to the tank body 37 (4). As a result, the elastic sheet 41 and the resin film 42 are sandwiched between the main body 37 and the side plate 38 of the distribution tank and bonded and welded (5), and the elastic sheet 41 and the resin film 42 can be reliably fixed to the distribution tank 21. The elastic sheet 41 and the resin film 42 can be prevented from peeling off.

FIG. 11 is a configuration diagram for explaining attachment in an example in which the elastic sheet 41 is disposed on the inner side and the resin film 42 is disposed on the outer side.
In this configuration example, the elastic sheet 41 is affixed while being positioned inside the resin film 42 (inside the tank), so that negative pressure fluctuations during printing can be quickly absorbed. Further, since the elastic sheet 41 and the resin film 42 are directly bonded or welded to the side plate 38 and sandwiched between the tank main body 37, the side plate or the tank main body as in the conventional example of FIGS. It can be made harder to peel than simply pasting. Moreover, since the elastic sheet 41 is located on the inner side, as shown in the enlarged view, the elastic sheet bonding portion Sb is located outside the resin film bonding portion Sa. It can also serve as a sealing function during pasting. Note that the bonding portion Sc is a bonding portion between the side plate 38 and the tank body 37.

Next, improvement in responsiveness during pressure maintenance will be described with reference to FIGS.
Ink jet printers require maintenance after being left for a long time, and pressure maintenance is a candidate at that time. The pressurization maintenance is to apply pressure to the sub tank with a pressurization pump and transmit the pressure to the head through the distribution tank to discharge nozzle clogging and air. It has also been found that applying the pressure rapidly is effective.

  At the end of the side plate 38 of the distribution tank 21, as shown in FIGS. 12 (a) and 13 (a), a convex portion 38 b is provided, so that there is a space between the elastic sheet 41 and the side plate at this portion. If present, during the pressure maintenance (the state where the sheet 41 and the film 42 are swollen), the elastic sheet 41 does not immediately follow the step of the side plate and tries to swell little by little, and it takes time until the normal pressure is transmitted to the head. It is possible that it will take.

  Therefore, as shown in FIG. 12B, the inner side (upper side in the figure) portion 38c of the convex portion 38b at the end of the side plate has a curved cross section, and the space between the elastic sheet 41 at the end of the side plate is defined. By eliminating it, the elastic sheet 41 and the resin film 42 can follow the side plate surface in a short time during pressurization, and the pressure can be immediately transmitted to the head. In addition, since the side where the said curved shape part 38c is provided is an inner part in each edge part of the side plate 38, the curved shape part 38c is provided in the downward side of the convex part 38b in the upper end part of the side plate 38, for example.

  In the example of FIG. 12B, the curved portion 38c is provided integrally with the convex portion 38b. However, as shown in FIG. 13B, by adding another member 43 inside the convex portion 38b, You may comprise so that the space in a side-plate edge part may be eliminated. Note that the position where the additional member 43 is added is the inner portion at each end of the side plate 38, as in the example of FIG. 12B. Therefore, for example, the upper end portion of the side plate 38 is separately provided below the convex portion 38b. The member 43 is provided.

  FIG. 13 shows a configuration in which the elastic sheet 41 is disposed on the inner side of the tank and the resin film 42 is disposed on the outer side (see FIG. 11). In this case also, the elastic sheet 41 is disposed on the inner side of the tank. Similar to the configuration, the elastic sheet 41 and the resin film 42 can follow the side plate surface in a short time during pressurization, and pressure can be immediately transmitted to the head.

  Incidentally, the side plate 38 of the distribution tank 21 is provided with an air communication hole 40 (see FIGS. 6, 8, and 11). During the pressurization maintenance, the elastic sheet 41 and the side plate are interposed via the communication hole 40. The air can be immediately released to the outside (atmosphere).

  As mentioned above, although this invention was demonstrated by the example of illustration, this invention is not limited to this. In the above embodiment, the line type apparatus has been described, but the present invention can also be applied to a serial type ink jet apparatus. Further, the number and arrangement of heads and head modules are also examples, and can be changed as appropriate. Further, the shape and configuration of the distribution tank can be appropriately set within the scope of the present invention. In addition, an appropriate configuration can be adopted for the recording medium conveyance unit, the cleaning device, and the like.

DESCRIPTION OF SYMBOLS 1 Apparatus main body 2 Paper feed tray 3 Paper discharge tray 4 Conveyance part 5 Cleaning apparatus 10 Head part 11 Head module 12 Head 13 Nozzle group 21 Distribution tank 22 Sub tank 26 Main tank 15 Conveyance guide part 27, 33 Supply tube 35 Head connection member 36 Distribution tank fixing member 37 Tank body 38 Side plate 40 Air communication hole 41 Elastic sheet 42 Gas barrier resin film

JP 2004237756 A JP 2001-199077 A JP 2008-143027 A

Claims (7)

An image forming apparatus including a plurality of droplet discharge heads for discharging droplets, the image forming apparatus including a distribution tank that distributes and supplies liquid to each of the plurality of droplet discharge heads, and the distribution tank includes a wall surface constituting the distribution tank At least one of the opening is provided, and has a damper portion that is elastically deformed in response to a pressure change in the distribution tank so as to close the opening.
The damper part is formed of two layers of an elastic sheet that is elastically deformable and a film that is less permeable than the elastic sheet,
The elastic sheet and the film are provided corresponding to substantially the entire surface of the wall surface of the distribution tank,
An image forming apparatus, wherein the film has a portion bent away from the elastic sheet.   The image forming apparatus according to claim 1, wherein the film is disposed inside a tank of the elastic sheet.   The image forming apparatus according to claim 1, wherein the elastic sheet is disposed inside the tank of the film.   The image forming apparatus according to claim 1, wherein the elastic sheet and the film are bonded to each other at a substantially central portion. The elastic sheet and the film are directly bonded or welded to a tank side plate constituting a housing of the distribution tank,
5. The image formation according to claim 1, wherein the elastic sheet and the film are sandwiched between the tank side plate and a tank main body constituting a housing of the distribution tank. apparatus.   The image forming apparatus according to claim 5, wherein the end portion of the elastic sheet and the end portion of the film are bonded or welded to the tank side plate in a state where the end portion of the elastic sheet is shifted. The shape of the inner surface of the tank side plate near the bonded or welded portion with the elastic sheet and the film is configured so that the elastic sheet and the film can follow the tank side plate when the tank pressure increases. The image forming apparatus according to claim 5, wherein the image forming apparatus is an image forming apparatus.

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