JP2013082140A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus having a configuration enabling prevention of upsizing of the apparatus, in view of a problem when a damper mechanism is included in a distribution tank.SOLUTION: In the image forming apparatus 1000, a recording head 1005 in which a plurality of head units 1006 are arranged in parallel includes a mechanism for pressurizing and sending liquid supplied from a liquid tank 1010 via the distribution tank 1008, the head units having a plurality of nozzles for discharging liquid droplets, and the distribution tank 1008 includes the damper mechanism 1023 for absorbing pressure fluctuation. At one end in a direction of an arrangement of the nozzle in the distribution tank 1008, the damper mechanism is coupled to the distribution tank 1008, using a piston 2000 which is slidable in response to the pressure fluctuation.

Description

  The present invention relates to an image forming apparatus, and more particularly to a damper mechanism used in an ink jet recording apparatus.

  In an inkjet recording apparatus used as one of various image forming apparatuses such as a printer, a facsimile, a copying apparatus, and a plotter, a line-type head in which nozzle rows are arranged corresponding to the entire width of a sheet to be conveyed is provided. Unlike a serial type image forming apparatus in which the head moves, a line type image forming apparatus that performs image formation by discharging droplets while maintaining a state in which the head does not move in the main scanning direction, so-called a line printer is known. (For example, Patent Document 1).

  In the line printer, as disclosed in Patent Document 1, a recording head in which a plurality of heads are arranged, a main tank for storing ink, and ink supplied from the main tank are stored in the recording head. An ink supply system that can handle deaerated ink including a sealed sub-tank formed of a flexible member to be supplied (for example, a flexible film), and distributes and supplies (branches) ink to a plurality of recording heads. There is a distribution member (hereinafter also referred to as a distribution tank) as a supply member and a means for discharging bubbles accumulated in the distributor tank from the ink supply path.

  The above-mentioned distribution tank directly connected to the plurality of heads is provided with an air discharge mechanism at the upper part for releasing air at the initial filling of ink or exhausting the accumulated air, and the internal top surface is easy to draw air. In order to do so, it is inclined.

  On the other hand, a configuration is known in which a damper mechanism is formed using a flexible member formed in a film shape on the wall portion of the distribution tank in order to adjust pressure generated during external vibration, mechanical vibration, or pulsation ( For example, Patent Documents 1 to 3).

  The flexible member has a shape that can follow a part of the ink storage space according to the space shape of the distribution tank. In the case of Patent Document 1, the internal top surface is inclined. The side view is triangular.

  The flexible member in the damper mechanism is maintained in a state of bulging outward by an urging member such as an elastic body in advance, so that the pressure during ink ejection can be maintained.

  However, the flexible member and the elastic body are provided in a direction perpendicular to the direction in which the heads are arranged so that the pressure fluctuation is propagated relatively quickly. For this reason, the space for the elastic body is required in the ink storage space, and the area of the flexible member needs to be increased in order to increase the absorbability for suppressing vibration. There is a risk of increasing the size of the apparatus.

  An object of the present invention is to provide an image forming apparatus having a configuration capable of preventing an increase in size of the apparatus in view of the problems in the above-described conventional image forming apparatus, particularly in the case where a distribution tank is provided with a damper mechanism. There is.

  In order to achieve this object, according to the present invention, a liquid supplied from a liquid tank is pressure-fed via a distribution tank to a recording head in which a plurality of head units each having a plurality of nozzles for discharging droplets are juxtaposed. An image forming apparatus having a configuration in which a damper mechanism that absorbs pressure fluctuations is provided in the distribution tank, wherein the damper mechanism is connected to one end of the nozzle in the arrangement direction of the nozzles. In the image forming apparatus.

  According to the present invention, the damper mechanism is provided not at the inside of the distribution tank but at one end of the nozzle in the distribution tank, so when the damper mechanism is provided within the distribution tank, the damper mechanism within the distribution tank The installation area of the flexible member used can be reduced. This prevents an increase in the size of the distribution tank, and in particular, depending on the function of the damper mechanism located at one end of the nozzle arrangement direction, it is not necessary to provide a special damper mechanism in the distribution tank. The distribution tank can be downsized.

1 is a diagram for explaining a configuration of an image forming apparatus according to an embodiment. FIG. FIG. 2 is a plan view of the image forming apparatus illustrated in FIG. 1. FIG. 2 is a schematic diagram for explaining a schematic configuration of an ink supply unit used in the image forming apparatus shown in FIG. 1. It is a figure for demonstrating the prior art example regarding the distribution tank used for the image forming apparatus shown in FIG. It is sectional drawing for demonstrating the structure of the flexible member used for the distribution tank shown in FIG. It is a figure for demonstrating the structure for attaching the flexible member shown in FIG. 5 to a distribution tank. It is a figure for demonstrating the structure of the attaching part by the side of the distribution tank used for the attachment structure shown in FIG. It is a figure for demonstrating the structure of the distribution tank used for the image forming apparatus shown in FIG. It is a figure for demonstrating each member of the distribution tank shown in FIG. It is a figure for demonstrating another example of the damper mechanism provided in a distribution tank. It is a figure for demonstrating each member of the distribution tank shown in FIG. It is a figure for demonstrating the other example of the damper mechanism provided in a distribution tank. It is a figure for demonstrating each member of the distribution tank shown in FIG.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration of an ink jet recording apparatus 1000 which is one of image forming apparatuses.

  An image forming apparatus 1000 shown in FIG. 1 is a line type image forming apparatus in which a head for ejecting liquid droplets from nozzles has a line configuration over almost the entire width of a recording medium. It is a thing of the structure to be done. The present invention is not limited to this method but can be applied to a serial type and a line type. In this embodiment, a line type image forming apparatus is mainly described as an example.

  The image forming apparatus 1000 includes an apparatus main body 1001, a paper feed tray 1002 that stacks and feeds recording media S, a paper discharge tray 1003 that discharges and stacks printed recording media S, and discharges the recording medium S from the paper feed tray 1002. A transport unit 1004 that transports to a paper tray 1003, a head unit that discharges and prints droplets onto a recording medium during the transport, a so-called head module 1005, and a cleaning device that cleans the nozzles of the head 1006 provided in the head module 1005. 1007.

  The apparatus main body 1001 includes front and rear side plates and stays (not shown). The recording medium S stacked on the paper feed tray 1002 is separated one by one by a separation roller 1002B and a paper feed roller 1002A, and is conveyed by a conveyance unit. Sent to 1004.

The transport unit 1004 includes a transport drive roller 1004A, a transport driven roller 1004B, and an endless belt 1004C. The endless belt 1004C is stretched between the transport drive roller 1004A and the transport driven roller 1004B.
A plurality of holes are formed on the surface of the endless belt 1004C, and the recording medium S is conveyed while being sucked onto the endless belt 1004C by a suction fan 1004D disposed at the lower portion of the endless belt 1004C.

  A conveyance guide roller 1004E can be brought into contact with and separated from the conveyance path of the recording medium S by a guide member (not shown) above the conveyance driving roller 1004A and the driven roller 1004B. When the conveyance driving roller 1004A is rotated by a motor (not shown), the conveyance driven roller 1004B and the conveyance guide roller 1004E are driven to rotate and convey the recording medium S.

A head unit (head module) 1005 that discharges droplets to be printed on a recording medium is disposed above the transport unit 1004.
The head module 1005 is movable in the sheet passing direction of the recording medium S, and slides to the top of the cleaning device 1007 during cleaning.

  In the head module 1005, a head unit 1006 equipped with heads 201 to 205 (see FIG. 2) for discharging droplets is formed over almost the entire width of the recording medium S. As shown in FIG. Five units 1006 are arranged (for convenience, indicated by reference numerals 201 to 205 in FIG. 2), and arranged in a staggered 4-row arrangement (for convenience, reference numerals 1005a to 1005d corresponding to the head modules in FIG. 2). ).

In FIG. 2, among the head modules 1005a to 1005d having the heads (201 to 205), the head modules denoted by reference numerals 1005a and 1005b are for black (K) and magenta (M) inks, and reference numerals 1005c, The head module indicated by reference numeral 1005d is set to target cyan (C) and yellow (Y) inks, and is arranged in a staggered manner to form one image line of 150 dpi.
The configuration of the head is not limited to these examples, and it is also possible to arrange two head portions and add one color ink to each head, thereby increasing the image resolution.

As shown in FIG. 1, distribution tanks 1008a to 1008d for supplying ink to the respective heads are arranged on the upper portion of the head module 1005 for each color.
In FIG. 3 showing one of them, a sub tank 1009 is arranged on the upstream side of the distribution tanks 1008a to 1008d, and a meniscus of the head is held by a spring (a member indicated by a broken line in the drawing) in the sub tank 1009. Negative pressure (-20 to -70 mmAq).

  The sub tank 1009 is a pack type. 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. A filter 1009A is disposed inside the sub tank 1009 so that dust in the ink does not flow into the head and cause nozzle clogging.

In FIG. 2, a main tank 1010 for storing ink is disposed upstream of the sub tank 1009. In FIG. 2, colors to be stored are indicated by symbols Y, C, M, and K, and any main tank 1010 is connected to the sub tank 1009 through a supply path using tubes.
The main tank 1010 can supply ink by pressurizing the inside of the cartridge by a pressure pump P, and is pressurized at a predetermined pressure all at once after the apparatus is turned on.

  In the sub tank 1009 described above with reference to FIG. 3, the ink amount is monitored by a detection means (not shown). When the ink is insufficient, the electromagnetic valve 1020 is opened and closed as necessary, and the main tank 1010 is connected via the supply tube 1019. Ink is supplied from.

In FIG. 1, a conveyance guide unit 1011 using a roller for discharging a recording medium to a paper discharge tray 1003 is formed on the downstream side of the conveyance unit 1004.
The recording medium S transported by the transport guide unit 1011 is discharged to a paper discharge tray 1003.
The paper discharge tray 1003 includes a pair of side fences 1003A that regulates in the width direction of the recording medium S and an end fence 1003B that regulates the leading end of the recording medium S.

A cleaning device 1007 for cleaning the nozzle surface of the head is provided below the transport guide portion 1011.
In the cleaning device 1007, cleaning means (indicated by reference numerals 1007a to 1007d in FIG. 2) corresponding to the number (four) of each head module (members indicated by reference numerals 1005a to 1005d in FIG. 2) are juxtaposed. As with the head module, the cleaning means is configured in a staggered manner over almost the entire width of the recording medium.
As shown in FIG. 1, the cleaning device 1007 is provided with suction pumps 1012 corresponding to the number of the cleaning units below so that ink from the head can be sucked.

  In the cleaning device 1007, a cleaning operation is performed on the head after printing is completed. In the cleaning operation, when a head that discharges droplets is capped and ink is sucked, or when ink that adheres to the nozzle surface of the head is cleaned with a wiper blade (not shown), the transport unit 1004 transports the ink after stopping printing. The driven roller 1004B is pivoted counterclockwise to secure a moving space for the head portion.

  In addition, when the guide function is canceled by rotating the conveyance guide portion 1011 arranged at the upper portion of the cleaning device 1007 in FIG. 1 counterclockwise with respect to the fulcrum portion L, the head module 1005 is shown in FIG. Then, when it moves in the direction of arrow A and reaches the top of the cleaning device 1007, it stops at that position and then moves to the cleaning operation of each head.

Here, in order to make it easy to understand the features of the present embodiment, in FIG. 4, a conventional configuration of the distribution tank 1008 and the heads 201 to 205 (see FIG. 2) provided in the head module 1005 (see FIG. 2). Is described as follows.
In the same figure, several heads (five are shown in the figure, but one may be sufficient) 201-205 are being fixed to the head connection member 1006c by fixing members (screw, adhesive, etc.) which are not illustrated. .

  The heads 201 to 205 are provided with a filter 1021 as shown in FIG. 4B for the purpose of individually removing foreign matters in the ink, and the heads 201 to 205 and the filter 1021 A module 1005 is configured (hereinafter, the head is used synonymously with the head unit).

  In FIG. 4, a distribution tank 1008 is fixed to the upper part of the head module 1005 by a distribution tank fixing member 1022. The distribution tank fixing member 1022 is a plate spring that is pressed up and down in the drawing, and the distribution tank 1008 is pressed against the head portion 1006.

The inside of the distribution tank 1008 is divided as shown in FIG.
For this reason, as shown in FIG. 4C, two colors can be used with one head. As described above, the configuration of the distribution tank and the head is not limited to these examples. The configuration is such that one color ink is put in each head without dividing the distribution tank, and the number of heads is increased. A configuration with an increased image resolution is also acceptable.

  Here, the flexible member (damper) 1023 installed in the distribution tank 1008 for pressure adjustment from (external vibration, mechanical vibration) is installed on the side surface of the distribution tank 1008 as shown in FIG. ing.

  FIG. 5 is a cross-sectional view showing the configuration of the flexible member 1023. In the figure, the flexible member 1023 is made of PE (or PP), NY from the viewpoint of improving the weldability to the distribution tank 1008 and improving the gas barrier. (Or EVOH, PET), and the structure has two or more layers, and in the figure, a three-layer structure (PE / EVOH / NY, PP / silica / PET) is shown. Since the nozzle of the recording head used in this embodiment is extremely fine (φ24 μm), if the amount of dissolved oxygen in the ink is high, the oxygen gradually accumulates and the risk of ink discharge failure increases. As a material used for the supply path, a material having a high gas barrier property that does not allow air to enter the ink liquid is used.

  The above-described distribution tank 1008 is used for air bleeding when initially filling the empty distribution tank 1008, and thereafter, when air is temporarily collected in the divided space in the distribution tank 1008. For this reason, the distribution tank 1008 has an inclined upper surface as shown in FIG. 4A in order to facilitate air extraction, and a waste liquid tube 1017 connected to a waste liquid tank (not shown) is connected to the highest position of the inclined upper surface. Has been.

  FIG. 6 is a diagram showing a configuration for welding the flexible member 1023 and the distribution tank 1008. In the drawing, as shown in FIG. 7, the distribution tank is formed with a plurality of weld ribs (indicated by reference numeral RB) having a triangular cross section formed on the wall surface on the distribution tank 1008 side. The layered gas barrier film is pressed while applying heat. The weld rib and the PE (or PP) layer of the film are melted and welded by heat. The welding temperature is about 170 degrees for PE and about 200 degrees for PP.

The features of the present embodiment will be described with the above configuration as an object.
A feature of the present embodiment is that a damper mechanism is provided at a position different from the inside of the distribution tank 1008, that is, at one end of the distribution tank 1008 in the nozzle arrangement direction. Hereinafter, this configuration will be described. In addition, in the drawings after FIG. 8, the same members as those shown in FIG.

FIG. 8 is a view showing an embodiment of the damper mechanism. In the drawing, the top surface of the distribution tank 1008 is not inclined unlike the case shown in FIG. The reason for this will be explained later.
For this reason, the distribution tank 1008 differs from the conventional structure shown in FIG. 4 in that the top surface is not inclined, but the wall in the direction perpendicular to the nozzle arrangement direction is flexible as in the conventional structure. A sex member 1023 can also be provided.
In this case, the opening (indicated by reference numeral 10080 for convenience) where the flexible member 1023 is installed has a rectangular shape because the top surface of the distribution tank 1008 is not inclined, and the height direction in the nozzle arrangement direction The dimensions are uniform. In addition, from the viewpoint of manufacturing parts, a rectangular hole such as a square hole was provided and closed with a film or the like, but it may be closed by installing a plate or the like. If there is no problem in manufacturing, a square hole is not provided. May be.

On the other hand, at one end of the distribution tank 1008 in the direction in which the nozzles are arranged, a piston 2000 is provided which is disposed in a space communicating with the distribution tank 1008 and is slidable due to pressure fluctuation in the distribution tank 1008.
As shown in FIG. 9, the piston 2000 is slidable in a state of being sealed by a packing 2001 that contacts the inner surface of the space communicating with the distribution tank 1008.

The piston 2000 is provided with an elastic body 2002 such as a spring that can be positioned at a predetermined position when a pressure fluctuation does not occur by applying a pressure that is balanced with the ink filling pressure in the distribution tank 1008. .
The elastic body 2002 has one end in the extension direction located on the piston 2000 side, and the other end in the extension direction is located on the inner surface of the lid 2003 that can block the end of the distribution tank 1008 and is prevented from falling off. The lid 2003 is integrated at the end of the distribution tank 1008 by screwing or welding, bonding, or snap fitting.

In the configuration as described above, when the damper mechanism using the flexible member 1023 is provided in the distribution tank 1008, the pressure fluctuation in the distribution tank 1008 is caused by the sliding operation of the piston 200 located at one end in the nozzle arrangement direction. Therefore, the installation area of the existing flexible member 1023 can be reduced. This is the reason why the inclined surface is not provided when the damper mechanism is provided in the distribution tank 1008. Thereby, since it is not necessary to use the above-described inclined surface, the bulk of the distribution tank 1008 does not increase.
In particular, if it is not necessary to provide a damper mechanism using the flexible member 1023 in the distribution tank 1008, the distribution tank 1008 can be further downsized.
According to this configuration, it is possible to avoid an increase in the bulk of the distribution tank with a simple configuration.

Next, another embodiment relating to the damper mechanism will be described.
The embodiment shown in FIGS. 10 to 13 is characterized in that a flexible member that can expand and contract in accordance with pressure fluctuations of the distribution tank 1008 is provided in a space communicating with one end of the distribution tank in the nozzle arrangement direction.

In the embodiment shown in FIG. 10, a conical flexible member 2005 is attached to one end of the distribution tank 1008 in the nozzle arrangement direction.
The flexible member 2005 is an expandable member that has an internal space that bulges outward from the end, and the material used is of a multilayer structure used for the flexible member 1023. A film made of rubber sheet, aluminum, low density or high density polyethylene, fluororesin, vinyl chloride, PVA, polypropylene, nylon, PET or the like is used.

As shown in FIG. 11, the flexible member 2005 has a conical head that protrudes outward from one end in the nozzle arrangement direction of the distribution tank 1008 and a base portion that is located on the space side communicating with the distribution tank 1008. The base portion is sandwiched and sealed together with a packing 2001 disposed between the end surface at one end of the nozzle arrangement direction of the distribution tank 1008 and the inner surface of the lid 2003.
The flexible member 2005 is provided in a state in which the conical head protrudes outward from one end of the nozzle arrangement direction of the distribution tank 1008, so that it always receives the pressure from the distribution tank 1008, that is, the ink filling pressure. . For this reason, it is not necessary to use the elastic body 2002 shown in FIGS.

In the above embodiment, the pressure fluctuation in the distribution tank 1008 is absorbed by the expansion and contraction deformation of the flexible member 2005 connected to one end of the distribution tank 1008 in the nozzle arrangement direction.
As a matter of course, the distribution tank 1008 can reduce the installation area when the flexible member 1023 is provided, so that the top surface is not inclined and the distribution tank 1008 is distributed as in the example shown in FIG. An increase in the bulk of the tank 1008 can be prevented.

In the configuration shown in FIG. 12, contrary to the case shown in FIG. 10, a flexible member (indicated by reference numeral 2005 ′ for convenience) positions the conical head inside the distribution tank 1008.
As shown in FIG. 13, the base portion of the flexible member 2005 ′ is attached by being sandwiched between the end surface at one end in the nozzle arrangement direction of the distribution tank 1008 and the inner surface of the lid 2003.
On the other hand, an elastic body such as a spring that urges the flexible member 2005 ′ to maintain an expanded state when no pressure fluctuation occurs in the distribution tank 1008 (for convenience, as shown in FIG. 8). Is used).

In the above embodiment, the pressure fluctuation in the distribution tank 1008 is absorbed by the expansion and contraction deformation of the flexible member 2005 ′ having a conical head in a state of entering the one end in the nozzle alignment direction in the distribution tank 1008. Will be.
As a matter of course, the top surface of the distribution tank 1008 is not inclined, and the bulk of the distribution tank 1008 can be prevented from increasing in size as in the example shown in FIGS. .

1000 Image forming apparatus 1005 Head unit (head module)
1006 Head 1008 Distribution tank 10080 Flexible member mounting hole 1009 Sub tank 1010 Main tank 2000 Piston 2001 Packing 2002 Elastic body 2003 Lid 2005, 2005 ′ Flexible member

JP 2011-56789 A JP 2009-83378 A JP 2009-234151 A

Claims (6)

A recording head having a plurality of head units each having a plurality of nozzles for discharging droplets is configured to supply liquid supplied from a liquid tank under pressure through a distribution tank, and the distribution tank has pressure fluctuations. In an image forming apparatus provided with a damper mechanism that absorbs
The image forming apparatus, wherein the damper mechanism is coupled to one end of the nozzle in the arrangement direction of the distribution tank.   The damper mechanism includes a piston that is disposed in a space communicating with the distribution tank and is slidable by pressure fluctuation in the distribution tank, and an elastic body that holds the piston in a predetermined position. The image forming apparatus according to claim 1.   2. The damper mechanism according to claim 1, wherein a space communicating with the distribution tank includes a flexible member that can expand and contract in accordance with pressure fluctuations in the distribution tank. Image forming apparatus.   The image forming apparatus according to claim 3, wherein the flexible member is provided with a conical head located inside or outside one end of the distribution tank in the arrangement direction of the nozzles.   The flexible member maintains a volume of the flexible member at a predetermined volume when no pressure fluctuation occurs when the conical head is located in a space communicating with the distribution tank. 5. The image forming apparatus according to claim 3, further comprising an elastic body.   The image forming apparatus according to claim 3, wherein the flexible member is formed of a film.

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