JP2005119031A - Damper structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image recording apparatus which can always carry out high-definition image recording by absorbing a pressure variation of ink by a simple arrangement, and by preventing discharge failures of ink. <P>SOLUTION: In a damper 1 structure set in the halfway of an ink supply pipe 9a for supplying ink to an inkjet head 7 which discharges the ink from an intermediate tank 8 where the ink is stored, there are set an ink chamber 12 equipped with an ink inlet 19 and an ink outlet 19, and an air chamber 13 for adjusting a pressure in the ink chamber 12. A filter 15 is installed at the ink outlet 19. A flexible film 11 is set as a separating member for separating the ink chamber 12 and the air chamber 13 from each other. An air pump 17 and an opening and closing valve 18 are set as a pressure adjustment mechanism for adjusting a back pressure applied to the flexible film 11 in the air chamber 13. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a damper structure, and more particularly to a damper structure in an ink jet printer.

  2. Description of the Related Art Conventionally, an ink jet printer has been proposed and put into practical use as an image recording apparatus capable of recording an image on various recording media such as plain paper and plastic thin plate. An ink jet printer records a predetermined image on a recording medium by discharging ink as fine droplets from an ink discharge port of an ink jet head toward the recording medium.

  In an inkjet head, for example, a piezoelectric element that is deformed by applying a voltage is disposed in an ink flow path that supplies ink to an ink discharge port, and ink is discharged from the ink discharge port by applying a voltage to the piezoelectric element. It is like that. However, in the ink jet head having such a structure, when ink pressure fluctuation in the ink flow path occurs in the process of supplying ink from the ink tank to the ink jet head, so-called dot omission occurs during printing, There is a risk that normal ink ejection may not be performed, for example, so-called crosstalk occurs in which ink is ejected from an ink ejection port different from the location where ink should be ejected. When such ejection abnormality occurs, high-definition image recording cannot be performed.

For this reason, conventionally, a damper is provided as a mechanism that absorbs ink pressure fluctuation caused by inflow and outflow of ink in a part of an ink supply pipe that supplies ink from an ink tank to an inkjet head (for example, Patent Document 1).
Japanese Utility Model Publication No. 5-44539

  Such a damper is generally provided with a plate urged toward the inside of the damper by a spring or the like, and when ink flows into the damper, the plate is pushed outward by the pressure of the ink, and this pressure is reduced. Absorption by the spring for urging the plate absorbs pressure fluctuations accompanying the inflow of ink.

  However, in the case where the ink pressure is absorbed by the spring as described above, the spring needs to have sufficient strength to absorb the ink pressure. For this reason, when the ink flows in, it receives a resistance by a spring, and the damper effect is reduced accordingly. Therefore, there is a problem that the ink pressure fluctuation may not be sufficiently absorbed.

  Accordingly, the present invention has been made to solve the above-described problems, and an object thereof is to provide a damper structure that can obtain a sufficient damper effect with a simple configuration.

In order to solve such a problem, the invention described in claim 1 is a damper structure provided in the middle of an ink supply path that supplies ink to an inkjet head that discharges ink from an ink tank that stores ink.
An ink chamber having an ink inlet and an ink outlet, and an air chamber for adjusting the pressure in the ink chamber; a filter is provided at the ink outlet, and a partition member for partitioning the ink chamber and the air chamber is allowed. While being made of a flexible material, the air chamber is provided with a pressure adjusting mechanism for adjusting a back pressure applied to the partition member.

  According to the first aspect of the present invention, since the ink chamber and the air chamber constituting the damper are partitioned by the partition member formed of a flexible material, the partition member is outside when the ink flows into the damper. The ink pressure rise due to the inflow of ink can be absorbed by bending in the direction. In addition, since the pressure adjustment mechanism is provided in the air chamber, the back pressure inside the damper can be kept constant.

  The invention described in claim 2 is the invention according to claim 1, wherein an air pump is connected to the air chamber, and an open / close valve is provided between the air pump and the air chamber, and the air pump and the open / close valve are provided. The pressure adjusting mechanism is configured as described above.

  According to the second aspect of the present invention, the air inside the damper is evacuated by the air pump, and the air drawn by the air pump is prevented from flowing back into the damper by providing an on-off valve between the pump and the air chamber. The internal back pressure can be kept constant.

  According to the first aspect of the present invention, when the ink flows into the damper, the flexible partition member bends outward, so that an increase in ink pressure due to the inflow of ink can be absorbed. Unlike the damper configured to absorb the ink pressure by the spring, the ink pressure is absorbed without receiving extra resistance when the ink flows into the damper. For this reason, even when a large damper effect is required, it is possible to sufficiently reduce ink pressure fluctuations. As a result, even if ink pressure fluctuations occur in the ink flow path, defective ejection can be prevented, and an effect of stably recording a high-definition image can be achieved.

  According to the invention described in claim 2, by providing the air pump and the opening / closing valve in the air chamber provided for adjusting the pressure in the damper, the pressure of the air chamber can be kept constant. As a result, the back pressure in the damper can always be kept constant, so that the partition member can be held in a freely bending state, and the effect of reducing ink pressure fluctuation can be achieved.

  Hereinafter, an ink jet printer to which an embodiment of a damper structure 1 according to the present invention is applied will be described with reference to the drawings.

  First, as shown in FIG. 1, in this embodiment, the ink jet printer is a serial print type ink jet printer, and this ink jet printer has a platen 2 that is formed in a flat plate shape and supports a recording medium P from a non-recording surface. Is provided. Conveying rollers 3 and 4 for conveying the recording medium P while maintaining the recording medium P at substantially the same height as the platen 2 are rotatably provided on the upstream side and the downstream side of the platen 2, respectively. As the transport rollers 3 and 4 rotate, the transport rollers 3 and 4 are transported in the predetermined transport direction X along the upper surface of the platen 2.

  Above the platen 2, a rod-shaped guide rail 5 extending in the main scanning direction orthogonal to the conveyance direction X of the recording medium P is provided. A carriage 6 is supported on the guide rail 5, and the carriage 6 reciprocates in the main scanning direction along the guide rail 5 by a driving mechanism (not shown).

  On the carriage 6, four inkjet heads 7 corresponding to each color (yellow (Y), magenta (M), cyan (C), black (K)) used in the inkjet printer according to this embodiment are mounted as a group. Has been. A plurality of ink ejection ports (not shown) are provided on the surface of the inkjet head 7 facing the recording medium P, and each inkjet head 7 ejects ink from the ink ejection port. The ink used in the ink jet printer is not limited to this, and for example, colors such as light yellow (LY), light magenta (LM), and light cyan (LC) can be used. In this case, an ink jet head corresponding to each color is mounted on the carriage.

  Each of these inkjet heads 7 has an intermediate tank 8 for temporarily storing yellow (Y), magenta (M), cyan (C), and black (K) inks via an ink supply pipe 9a. It is connected. Each intermediate tank 7 is connected to a main ink tank 10 through an ink supply pipe 9b. The ink in each main ink tank 10 is supplied to the intermediate tank 8 through the ink supply pipe 9b, and is temporarily stored in the intermediate tank. After being stored in 8, it is supplied to each inkjet head 7.

  A damper 1 for adjusting the pressure of ink supplied to the inkjet head 7 is provided in the middle of the ink supply pipe 9 a and between the intermediate tank 8 and the inkjet head 7.

  As shown in FIG. 2, a flexible film 11 is provided inside the damper 1 as a partition member that partitions the damper 1 in the vertical direction in FIG. 2, and the inside of the damper 1 is the flexible film 11. Thus, the ink chamber 12 is divided into an ink chamber 12 into which ink flows and an air chamber 13 for adjusting the pressure in the damper.

  An ink inflow port 14 through which ink flows through an ink supply pipe 9a is provided at one lower end of the ink chamber 12. An ink outlet 19 through which ink flows out toward the ink jet head 7 is provided on one side of the ink chamber 12, and a filter 15 that removes impurities such as dust contained in the ink is attached to the ink outlet 19. It has been.

A coil spring 20 is provided between the filter 15 and the flexible film 11 so that one end is in contact with the filter 15 and the other end is in contact with the flexible film 11. A similar coil spring 21 is also provided between the flexible film 11 and the side wall of the air chamber 13 so that one end is in contact with the side wall of the air chamber 13 and the other end is in contact with the flexible film 11. The flexible film 11 is supported from both sides by coil springs 20 and 21, and the position of the flexible film 11 is maintained at the approximate center of the damper 1 by the coil springs 20 and 21.
As a result, when the ink flows into the ink chamber 12 and the flexible film 11 is bent toward the air chamber 13, the flexible film 11 is moved to the ink by the coil spring 21 provided on the air chamber 13 side. It is pushed back to the chamber 12 side. Further, when the ink flows out from the ink chamber 12 and the flexible film 11 is bent toward the ink chamber 12, the flexible film 11 is moved to the air chamber 13 by the coil spring 20 provided on the ink chamber 12 side. It is pushed back to the side. The coil springs 20 and 21 only need to apply a slight pressing force to the flexible film 11 that can maintain the position of the flexible film 11.

  A connecting pipe 16 to which an air pump 17 is connected communicates with one side surface of the air chamber 13, and an on-off valve 18 that prevents backflow of air is provided in the middle of the connecting pipe 16 that connects the air chamber 13 and the air pump 17. Is provided. The air pump 17 and the on-off valve 18 function as a pressure adjusting mechanism that adjusts the back pressure applied to the flexible film 11, and the air in the air chamber 13 is sucked by the air pump 17, and the air chamber 13, the ink chamber 12, The flexible film 11 can be held in a freely bending state by closing the on-off valve 18 after adjusting the back pressure to be balanced. As a result, when the ink flows from the ink inlet 14, the flexible film 11 bends toward the air chamber 13 side. The ink pressure can be absorbed between the ink film 11 and the ink pressure in the ink supply process does not change abruptly.

  Next, the operation of the ink jet printer to which the damper 1 according to this embodiment is applied will be described.

  When the power of the ink jet printer is turned on, power is supplied to each part of the ink jet printer, and the carriage 6 on which the ink jet head 7 is mounted moves above the platen 2.

  When the carriage 6 reaches a predetermined position, the recording medium P is transported in the transport direction X by the transport rollers 3 and 4, and at the same time, the carriage 6 reciprocates along the main scanning direction. At this time, ink of a required color is ejected from the ink ejection port of the inkjet head 7 based on predetermined image information. As a result, a predetermined image is recorded on the recording medium P.

  Ink is supplied to the inkjet head 7 from the main ink tank 10 through the ink supply pipes 9a and 9b as needed, and before the ink is supplied from the intermediate tank 8 to the inkjet head 7, the ink chamber in the damper 1 is temporarily provided. 12 flows in. Inside the damper 1, the opening / closing valve 18 is opened and an air pump 17 connected to the air chamber 13 sucks the air in the air chamber 13, and the opening / closing valve 18 is opened when the back pressure of the air chamber 13 and the ink chamber 12 is balanced. By closing, the flexible film 11 is held in a freely deflecting state. Thus, when the ink flows into the ink chamber 12, the flexible film 11 is bent toward the air chamber 13, and the coil spring 21 provided on the air chamber 13 side pushes the flexible film 11 back toward the ink chamber 12. By working in this manner, ink pressure fluctuations caused by the inflow of ink between the flexible film 11 and the filter 15 are absorbed.

  In this embodiment, when the ink flows into the damper 1, the flexible film 11 that partitions the ink chamber 12 and the air chamber 13 bends and absorbs the pressure fluctuation caused by the inflow of the ink. Unlike the case of absorbing the fluctuation, it is not necessary to provide a spring having a strong pressing force, and the spring only needs to have a pressing force capable of maintaining the flexible film 11 in a predetermined position. For this reason, the damper effect is not reduced by the pressing force of the spring. As a result, even when a large damper effect is required, the ink pressure can be sufficiently absorbed, thereby preventing ink ejection failure such as ink being ejected from an ink ejection port that should not eject ink. And high-definition images can be stably recorded.

  In the present embodiment, the damper 1 is provided between the intermediate tank 8 and the inkjet head 7. However, the position where the damper is provided is not limited to this, and the pressure of the ink is on the ink supply path. It is only necessary to be provided at a position where the fluctuation can be effectively absorbed.

  In this embodiment, the flexible film 11 is used as a partition member for partitioning the inside of the damper 1. However, the material constituting the partition member is not limited to this, and the pressure fluctuation of the ink flowing into the ink chamber 12 is used. What is necessary is just to be comprised with the material which has the flexibility which can absorb.

  In the present embodiment, the coil springs 20 and 21 for supporting the flexible film 11 from both sides are provided in order to hold the position of the flexible film 11 substantially at the center of the damper 1. The spring that supports the film 11 is not limited to the coil springs 20 and 21, and for example, a leaf spring or the like may be used. Moreover, you may make it hold | maintain the position of a flexible film in the substantially center of a damper only by the elasticity of a flexible film, without providing a spring.

  Further, in this embodiment, the ink jet printer to which the ink jet head 7 according to the present invention is applied reciprocates the ink jet head 7 mounted on the carriage 6 in the main scanning direction and transports the recording medium P in the transport direction X. However, the ink was ejected from the ink jet head to form an image by forming a serial head type ink jet printer, but the ink was ejected from the ink jet head fixed to the printer body and the recording medium was conveyed to form the image. It is also possible to apply to a line head type inkjet printer.

  In addition, it is needless to say that the present invention is not limited to the above embodiment and can be modified as appropriate.

It is explanatory drawing showing schematic structure of the inkjet printer provided with the damper in this embodiment. FIG. 2 is a side sectional view illustrating a schematic configuration of a damper of the ink jet printer of FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Damper 7 Inkjet head 11 Flexible film 12 Ink chamber 13 Air chamber 15 Filter 17 Air pump 18 On-off valve

Claims (2)

In a damper structure provided in the middle of an ink supply path that supplies ink to an inkjet head that discharges ink from an ink tank that stores ink,
An ink chamber having an ink inlet and an ink outlet, and an air chamber for adjusting the pressure in the ink chamber; a filter is provided at the ink outlet, and a partition member for partitioning the ink chamber and the air chamber is allowed. A damper structure characterized by comprising a flexible material and provided with a pressure adjusting mechanism for adjusting a back pressure applied to the partition member in the air chamber.   The air pump is connected to the air chamber, an on-off valve is provided between the air pump and the air chamber, and the pressure adjustment mechanism is configured by the air pump and the on-off valve. Damper structure.

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