JP6384350B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an ink jet image forming apparatus including a recording head that discharges ink onto a recording medium such as paper.

  2. Description of the Related Art Conventionally, an ink jet image forming apparatus includes a recording head that ejects ink onto a recording medium such as paper, and an ink container that accommodates the ink. Some have a sub ink tank at a low position and temporarily store ink supplied from an ink container to a recording head in the sub ink tank.

  The ink supplied from the ink container to the sub ink tank may include foreign matters mixed during manufacture of the ink container, foreign matters entering the supply port when the ink container is replaced, air, and the like. If foreign matter is mixed in the ink supplied to the recording head, non-ejection (clogging) occurs in the nozzles of the recording head. Therefore, in some image forming apparatuses, an ink filter is installed between the recording head and the sub ink tank in order to prevent foreign matter from being mixed into the ink supplied to the recording head, and the foreign matter is captured by this filter. .

  For example, in the ink jet recording apparatus disclosed in Patent Document 1, an ink tank that can store ink, a recording head that performs a recording operation for ejecting ink onto a recording medium, a supply path that supplies ink from the ink tank to the recording head, and a supply A filter provided in the middle of the path is provided to remove dust in the ink.

  The size of the ink filter that can be arranged in the supply path to the recording head is limited. If the ink filter becomes clogged, the flow resistance from the sub ink tank to the recording head increases, and ink is ejected by the recording head. After that, there is a delay in refilling ink. On the other hand, the above-described problems can be prevented by increasing the area of the ink filter or providing an exchangeable ink filter. However, if the ink filter is simply enlarged, there is a concern that the ink supply mechanism will increase in size, and if a replaceable ink filter is provided, replacement parts will be required and the cost will increase. There is a concern that foreign substances may enter during replacement.

  In the ink jet printer of Patent Document 2, a filter is provided between an ink introduction part provided in the lower part of the sub tank and an ink discharge part provided above the ink introduction part so that a large size filter can be used. Yes.

JP 2012-232447 A JP 2014-94460 A

  When the interior of the sub ink tank is completely separated on the ink supply side and the ink discharge side by the ink filter as in Patent Document 2, air entering from the ink supply port cannot be passed through the ink filter when replacing the ink container. When the ink filter is clogged, the volume of air increases every time the container is replaced, and the fluid resistance increases in the same manner as when the ink filter is clogged with foreign matter. As a result, the ink replenishment speed from the ink container to the sub ink tank is lowered, the ink refilling is delayed, and the ink supply is insufficient.

  In view of the above circumstances, an object of the present invention is to secure a sufficient size of an ink filter used for ink supply and prevent air from being clogged by the ink filter.

  An image forming apparatus according to the present invention includes a recording head that ejects ink onto a sheet, an ink container that stores the ink, and a recording head that is disposed below the recording head and supplies the recording head from the ink container. A sub-ink tank that temporarily stores the ink, and the sub-ink tank includes a supply port connected to the ink container and a discharge port connected to the recording head at a horizontal interval. In addition, an ink filter is provided that partitions the internal space of the sub ink tank into a first space on the supply port side and a second space on the discharge port side and is spaced apart from the ceiling surface of the sub ink tank. It is characterized by providing.

  According to the present invention, it is possible to secure a sufficient size of the ink filter used for supplying ink and prevent air from being clogged with the ink filter.

1 is a diagram illustrating a configuration of a printer according to an embodiment of the present invention. FIG. 2 is a schematic diagram illustrating a recording head, an ink container, and an ink flow path of a printer according to an embodiment of the invention. FIG. 3 is a cross-sectional view illustrating an ink supply unit and a drive mechanism in a printer according to an embodiment of the invention.

  First, an overall configuration of a color printer 1 (hereinafter, simply referred to as “printer 1”) as an ink jet image forming apparatus will be described with reference to FIG. Hereinafter, the front side in FIG. 1 is the front side (front side) of the printer 1.

  As shown in FIG. 1, the printer 1 includes a box-shaped printer main body 2. A paper feed cassette 3 for storing paper P is accommodated in a lower portion of the printer main body 2 so as to be drawn out.

  A conveyance path 4 for the paper P is formed on the right side of the printer body 2. A paper feed roller 5 is provided in the vicinity of the paper feed cassette 3 at the lower end of the transport path 4, and a transport roller 6 is provided to the right of the paper feed roller 5. A registration roller 7 is provided at the upper end of the conveyance path 4.

  At the center of the printer main body 2, a paper transport unit 8 that can be raised and lowered is provided. The paper transport unit 8 includes a transport frame 10, a driving roller 11, a driven roller 12, a tension roller 13, an endless transport belt 14, and an air intake unit 15.

  The driving roller 11 is rotatably supported at the upper left corner of the transport frame 10, the driven roller 12 is rotatably supported at the upper right corner of the transport frame 10, and the tension roller 13 is disposed at the center lower portion of the transport frame 10. It is rotatably supported.

  The conveyor belt 14 is wound around the driving roller 11, the driven roller 12 and the tension roller 13. The conveyance belt 14 is provided with a number of intake holes (not shown).

  The intake portion 15 is disposed so as to be surrounded by the conveyance belt 14, and has an intake port (not shown) on the upper side, and is configured to intake air from above the conveyance belt 14 to the inside.

  In addition, a pair of left and right lifting units 16 are provided below the transport unit 8 at the lower center of the printer body 2. Each elevating unit 16 includes a rotating shaft 17 and a cam 18 supported by the rotating shaft 17. Each rotary shaft 17 is connected to a drive unit (not shown) such as a drive motor. By operating this drive unit, the rotary shaft 17 rotates about the rotary shaft 17, and the posture of each cam 18 stands up (see FIG. 1) (see the solid line 1) and the lying posture (see the two-dot chain line in FIG. 1). Each cam 18 is configured to lift the transport frame 10 and raise the transport unit 8 by taking a standing posture, and to release the lift of the transport frame 10 and lower the transport unit 8 by taking a lying posture. ing.

  Further, four sets of recording heads 20 (20K, 20C, 20M, and 20Y) are arranged in parallel at the center of the printer main body 2 above the paper transport unit 8. Each recording head 20 corresponds to each color of black (K), cyan (C), magenta (M), and yellow (Y) in order from the upstream side (right side in the present embodiment) in the conveyance direction of the paper P. . Hereinafter, the symbols “K”, “C”, “M”, and “Y” are omitted for the recording head 20 except for the case of specifying the color. Each recording head 20 is provided with a nozzle (not shown) so as to face the upper surface of the conveyance belt 14.

  Four ink containers 21 (21K, 21C, 21M, and 21Y) are arranged in parallel on the top of the printer main body 2 so as to be detachable in the front-rear direction. The four ink containers 21 are provided for each ink color, and in order from the upstream side (right side in the present embodiment) in the transport direction of the paper P, black (K), cyan (C), magenta (M), The ink of each color of yellow (Y) is accommodated. Hereinafter, the symbols “K”, “C”, “M”, and “Y” are omitted for the ink container 21 except when a color is specifically described.

  Each ink container 21 is connected to each recording head 20 via a sub ink tank 22 and a syringe pump 23 (ink supply unit), and the ink stored in each ink container 21 is temporarily stored in the sub ink tank 22. After that, each recording head 20 is supplied by a syringe pump 23. The sub ink tank 22 and the syringe pump 23 are provided corresponding to each color of black (K), cyan (C), magenta (M), and yellow (Y), similarly to the recording head 20 and the ink container 21. However, in FIG. 1, only the sub ink tank 22 and syringe pump 23 corresponding to black (K) are illustrated, and the sub ink tank 22 and syringe pump corresponding to cyan (C), magenta (M), and yellow (Y). Illustration of 23 is omitted. The ink supply mechanism from the ink container 21 to the recording head 20 will be described later.

  A discharge mechanism 24 is provided on the left side of the printer body 2. The discharge mechanism 24 includes a drying device 25 provided on the upper left side of the paper transport unit 8, a discharge roller 26 provided on the left side of the drying device 25, and a printer provided below the discharge roller 26 via the discharge port 27. A paper discharge tray 28 that protrudes outside the main body 2 is provided.

  Next, an image forming operation of the printer 1 having such a configuration will be described.

  When the printer 1 receives image data from an external computer or the like, the paper P stored in the paper feed cassette 3 is sent out to the transport path 4 by the paper feed roller 5. The paper P sent out to the transport path 4 is transported to the downstream side of the transport path 4 by the transport roller 6, and is sent out from the transport path 4 to the upper surface of the transport belt 14 by the registration roller 7.

  At this time, the intake unit 15 is operated, and air is sucked from the upper surface side of the conveyance belt 14 to the intake unit 15 through the intake holes of the conveyance belt 14 and the intake port of the intake unit 15. Then, the sheet P sent out to the upper surface of the transport belt 14 is adsorbed on the upper surface of the transport belt 14 by the suction force of the intake portion 15.

  On the other hand, each recording head 20 is supplied with ink from each ink container 21. Each recording head 20 ejects ink to the paper P adsorbed on the conveyance belt 14 based on information of image data received from an external computer or the like. Thereby, a color ink image is formed on the surface of the paper P. The paper P on which the color ink image is formed is discharged on the discharge tray 28 from the discharge port 27 by the discharge roller 26 after the ink on the surface is dried by the drying device 25.

  Next, an ink supply mechanism from the ink container 21 to the recording head 20 will be described with reference to FIG.

  As shown in FIG. 2, the ink container 21 and the sub ink tank 22 are connected via a first ink flow path 30, and a control unit (not shown) is provided in the middle portion of the first ink flow path 30. A first electromagnetic valve 31 that is opened and closed by the opening is provided so as to open or close the first ink flow path 30.

  The sub ink tank 22 is disposed below the ink container 21 and slightly below the recording head 20 so as to store ink at a position lower than the ink container 21 and slightly lower than the recording head 20. Has been. The sub ink tank 22 and the syringe pump 23 are connected via a second ink flow path 32, and a middle portion of the second ink flow path 32 is opened and closed by a control unit (not shown). Two electromagnetic valves 33 are provided to open or close the second ink flow path 32. In the present embodiment, the end of the first ink flow path 30 on the sub ink tank 22 side is the supply port 40 of the sub ink tank 22 connected to the ink container 21, and the second ink flow on the sub ink tank 22 side. The end of the path 32 is a discharge port 41 of the sub ink tank 22 connected to the recording head 20. In the sub ink tank 22, the supply port 40 and the discharge port 41 are arranged at intervals in the horizontal direction so as to extend through the upper part of the sub ink tank 22. In particular, the discharge port 41 includes It extends to the vicinity of the bottom of the sub ink tank 22.

  The sub ink tank 22 includes an ink filter 42, an ink amount detection unit 43, an ink amount detection unit 44, an air vent 45, and an air filter 46.

  The ink filter 42 is erected on the bottom of the sub ink tank 22, and divides the internal space of the sub ink tank 22 into a first space on the supply port 40 side and a second space on the discharge port 41 side. Is provided from the first space on the supply port 40 side to the second space on the discharge port 41 side. The ink filter 42 is provided apart from the ceiling surface of the sub ink tank 22, that is, the height of the ink filter 42 is set lower than the internal height of the sub ink tank 22. The ink filter 42 is composed of, for example, a SUS mesh member.

  The ink amount detection unit 43 and the ink amount detection unit 44 are provided so as to detect the maximum ink amount in the sub ink tank 22. The ink amount detected unit 43 is, for example, a magnet member that can float by the ink in the sub ink tank 22. It is an electrode member such as a reed switch that can detect the floating ink amount detection portion 43. The ink amount detection unit 44 is provided below the uppermost part in the sub ink tank 22, and when the ink level in the sub ink tank 22 reaches slightly below the upper end of the ink filter 42. The ink amount in the sub ink tank 22 is detected as the maximum ink amount.

  The air vent 45 is formed to open at the top of the sub ink tank 22, and the air filter 46 is configured to prevent the foreign matter from entering the sub ink tank 22 through the air vent 45. 45.

  The syringe pump 23 and the recording head 20 are connected via a third ink flow path 34, and a third electromagnetic valve that is opened and closed by a control unit (not shown) in the middle portion of the third ink flow path 34. 35 is provided to open or close the third ink flow path 34.

  Next, the drive mechanism 50 for driving the syringe pump 23 and the syringe pump 23 will be described with reference to FIG.

  The syringe pump 23 is driven by a drive mechanism 50 when purging the recording head 20, and as shown in FIG. 3, a cylinder 51 formed in a cylindrical shape, a piston 52 formed in a disk shape, Is provided.

  At one end of the cylinder 51, a filling port 53 connected to the second ink flow path 32 (sub ink tank 22) and a discharge port 54 connected to the third ink flow path 34 (recording head 20) are provided. ing. The other end of the cylinder 51 is formed by opening a piston 52 so that the piston 52 can be inserted.

  The piston 52 is fitted in the cylinder 51 so as to be able to reciprocate. An O-ring 55 is attached between the outer peripheral surface of the piston 52 and the inner peripheral surface of the cylinder 51 so that the piston 52 can slide while sealing the inside of the cylinder 51. Hereinafter, the direction in which the piston 52 moves toward the filling port 53 side and the discharge port 54 side of the cylinder 51 is defined as the forward direction, and the direction in which the piston 52 moves toward the opening side of the cylinder 51 is defined as the backward direction. The origin O of the movement direction of the piston 52 is set near the other end of the cylinder 51 (see FIG. 3).

  The drive mechanism 50 includes a rack section 56, a drive gear 57, a roller 58, an idle gear 60, a motor 61, an origin detection section 62, and a detected section 63, that is, a rack and pinion system. It consists of

  The rack part 56 has a long shape in the movement direction of the piston 52. One end (end portion on the forward direction side) of the rack portion 56 is attached to the piston 52 from the cylinder 51 side, and is configured to reciprocate the piston 52 as the rack portion 56 moves in the forward and backward directions. Has been. A rack gear 64 having a plurality of teeth is provided at a lower portion of the rack portion 56 at intervals in the longitudinal direction (movement direction of the piston 52).

  The drive gear 57 is provided below the rack portion 55 and meshed with the rack gear 64 of the rack portion 55. The roller 58 is provided above the drive gear 57 with the rack portion 56 interposed therebetween. In other words, the drive gear 57 and the roller 58 sandwich the rack portion 56 from above and below.

  The idle gear 60 is provided below the drive gear 57 and has a small diameter gear 65 and a large diameter gear 66 coaxially. The small-diameter gear 65 of the idle gear 60 is meshed with the drive gear 57.

  The motor 61 is controlled by a control unit (not shown) to generate a driving force, and is provided below the idle gear 60 and has a gear portion 67 that transmits the driving force. The gear portion 67 of the motor 61 is meshed with the large diameter gear 66 of the idle gear 60.

  The origin detection unit 62 detects whether or not the piston 52 is located at the origin O, and is composed of, for example, a photo interrupter. The origin detection unit 62 is provided on the backward direction side of the rack unit 56. The detected portion 63 is provided at the other end (end portion on the backward direction side) of the rack portion 56 so as to be detected by the origin detecting portion 62 when the piston 52 is located at the origin O.

  Next, the ink supply operation from the ink container 21 to the recording head 20 will be described with reference to FIGS.

  First, as shown in FIG. 2, since the ink container 21 is provided at a position higher than the sub ink tank 22, when the first electromagnetic valve 31 is in the open state, the ink container 21 is pressurized by the water head difference. Then, ink is supplied to the sub ink tank 22 through the first ink flow path 30. When the ink in the sub ink tank 22 increases, the ink detected part 43 rises. When the ink detection unit 43 reaches the ink amount detection unit 44 below the uppermost part in the sub ink tank 22, the ink amount detection unit 44 detects the maximum ink amount. In response to the detection of the maximum ink amount, the first electromagnetic valve 31 is switched to the closed state, and the ink supply from the ink container 21 to the sub ink tank 22 is stopped. As a result, the ink in the sub ink tank 22 is maintained at the maximum ink amount, and air is provided above the ink surface between the first space on the supply port 40 side and the second space on the discharge port 41 side. A space S that can be distributed is provided.

  When performing normal printing, the second electromagnetic valve 33 and the third electromagnetic valve 35 are opened, and the sub ink tank 22 is provided at a position slightly lower than the recording head 20. The water head difference between the sub ink tank 22 and the recording head 20 is maintained within a certain range. For this reason, the inside of the recording head 20 can be maintained in a slightly negative pressure state.

  When purging the recording head 20, the second solenoid valve 33 is switched to the closed state while the third solenoid valve 35 is kept open, and the motor 61 is driven to rotate forward (arrow shown in FIG. 3). X1). The driving force of the motor 61 at this time moves the rack portion 56 through the gear portion 67, the idle gear 60 and the drive gear 57 of the motor 61 in order to move the rack portion 56 in the forward direction (see arrow Y1 shown in FIG. 3). 56.

  As the rack portion 56 moves in the forward direction Y1 by the driving force from the motor 61, the piston 52 of the syringe pump 23 slides in the forward direction Y1 in the cylinder 51, and the ink in the cylinder 51 is moved by the piston 52. Pressed. The second ink flow path 32 connected to the filling port 53 of the cylinder 51 is closed by the closed second electromagnetic valve 33, but the third ink flow path 34 connected to the discharge port 54 of the cylinder 51 is opened. Since the ink is opened by the third electromagnetic valve 35 in the state, the ink pressed in the cylinder 51 is supplied to the recording head 20 via the discharge port 54 and the third ink flow path 35. In the recording head 20, foreign matter or bubbles in the recording head 20 are ejected by the ink to which the pressing force is applied.

  When refilling the ink in the syringe pump 23 that has decreased due to the purge of the recording head 20, the second electromagnetic valve 33 is switched to the open state, the third electromagnetic valve 35 is switched to the closed state, and the motor 61 is turned on. Drive in reverse (see arrow X2 shown in FIG. 3). The driving force of the motor 61 at this time is transmitted to the gear portion 67, the idle gear 60, the drive gear 57, and the rack portion 56 in order to move the rack portion 56 in the backward direction (see arrow Y2 shown in FIG. 3).

  As the rack part 56 moves in the backward direction Y2 by the driving force from the motor 61, the piston 52 of the syringe pump 23 slides in the backward direction Y2 in the cylinder 51, and the inside of the cylinder 51 is depressurized. At this time, the third ink flow path 34 connected to the discharge port 54 of the cylinder 51 is closed by the closed third electromagnetic valve 35, but the second ink flow path connected to the filling port 53 of the cylinder 51. 32 is opened by the opened second electromagnetic valve 33, so that the ink in the sub ink tank 22 flows into the cylinder 51 via the second ink flow path 32 and the filling port 34 as the pressure in the cylinder 51 is reduced. Sucked up. When the rack part 56 moves in the backward direction Y2, the detected part 63 attached to the rack part 56 is detected by the origin detection part 62, and it is detected that the piston 52 has moved to the origin O. The reverse drive of the motor 61 is stopped.

  In addition, as described above, since the ink stored in the sub ink tank 22 is reduced by refilling the ink from the sub ink tank 22 to the syringe pump 23, the ink amount detected portion 43 is lowered. Thus, the ink amount detection unit 44 cannot detect the ink amount detection unit 43. Therefore, the first electromagnetic valve 31 is switched to the open state and the ink is supplied from the ink container 21 to the sub ink tank 22 until the ink in the sub ink tank 22 reaches the maximum ink amount again.

  In the present embodiment, as described above, the printer 1 includes the recording head 20 that ejects ink onto the paper, the ink container 21 that stores the ink, and the ink container 21 that is disposed below the recording head 20. A sub ink tank 22 for temporarily storing ink to be supplied to the recording head 20. The sub ink tank 22 includes a supply port 40 connected to the ink container 21 and a discharge port 41 connected to the recording head 20 at a horizontal interval, and the internal space of the sub ink tank 22 is provided as a supply port. An ink filter 42 is provided that is partitioned into a first space on the 40 side and a second space on the discharge port 41 side and is provided apart from the ceiling surface of the sub ink tank 22.

  As a result, a space S in which air can flow between the first space on the supply port 40 side and the second space on the discharge port 41 side is provided above the ink level in the sub ink tank 22. Therefore, in the sub ink tank 22, a sufficiently large ink filter 42 prevents foreign matter contained in the ink from entering the first space on the supply port 40 side into the second space on the discharge port 41 side. When the ink container 21 is replaced, the air that has entered the sub ink tank 22 from the ink container 21 via the supply port 40 can be released into the space S as described above without clogging the ink filter 42. it can. Accordingly, a pressure difference between the first space on the supply port 40 side and the second space on the discharge port 41 side in the sub ink tank 22 is prevented, and the pressure loss between the recording head 20 and the sub ink tank 22 is reduced. It is possible to prevent the rise and provide a stable image with the recording head 20. As described above, in the printer 1 of the present invention, it is possible to secure a sufficient size of the ink filter 42 used for supplying ink and to prevent air from being clogged with the ink filter 42.

  In the present embodiment, the sub ink tank 22 includes an ink amount detection unit 44 that detects the ink amount when the ink level reaches slightly below the upper end of the ink filter 42 as the maximum ink amount. Thereby, it is possible to reliably prevent foreign matters contained in the ink from entering the second space on the discharge port 41 side from the first space on the supply port 40 side through the space S above the ink filter 42. .

  Further, in the present embodiment, an air vent 45 is formed in the upper part of the sub ink tank 22. Thereby, the air escaped to the space S above the ink filter 42 in the sub ink tank 22 can be discharged to the outside, and the change in the atmospheric pressure in the sub ink tank 22 can be suppressed.

  In the present embodiment, the configuration of the rack-and-pinion type drive mechanism 50 has been described. However, the drive mechanism 50 is not limited to this configuration, and may be another configuration such as a ball screw type.

  In this embodiment, the case where the configuration of the present invention is applied to the printer 1 has been described. However, in another different embodiment, the configuration of the present invention is applied to other different image forming apparatuses such as a copying machine, a facsimile machine, and a multifunction machine. It is also possible to do.

1 Printer (image forming device)
20 recording head 21 ink container 22 sub ink tank 40 supply port 41 discharge port 42 ink filter 43 ink amount detected portion 44 ink amount detection portion 45 air vent hole

Claims (3)

A recording head for ejecting ink onto paper;
An ink container for containing the ink;
A sub ink tank that is disposed below the recording head and the ink container and temporarily stores the ink supplied from the ink container to the recording head;
The sub ink tank includes a supply port connected to the ink container and a discharge port connected to the recording head spaced horizontally, and an internal space of the sub ink tank is provided on the supply port side. An ink filter that is divided into a first space and a second space on the discharge port side and spaced from the ceiling surface of the sub ink tank,
The supply port and the discharge port of the sub ink tank are provided so as to extend through the upper portion of the sub ink tank,
At the top of the sub ink tank, an air vent is formed,
An air filter is attached to the air vent ,
The sub ink tank includes an ink amount detection unit that detects an ink amount when the ink level reaches a position slightly below the upper end of the ink filter as a maximum ink amount. . A housing connected at one end to the recording head and the sub ink tank; and a pressing portion movable in one direction approaching the one end and in another direction away from the one end in the housing. An ink supply unit having
A drive mechanism that includes a rack portion that is movable in the one direction and the other direction and is attached to the pressing portion, and that drives the pressing portion of the ink supply unit;
An origin detection unit that detects whether or not the pressing unit is located at the origin of the other direction in the housing;
The rack portion includes an end portion on the one-direction side that is attached to the pressing portion, and an end portion on the other direction side that includes the detected portion.
The origin detection unit is provided on the other direction side than the rack unit, and detects whether the pressing unit is located at the origin by detecting the detected unit.
When the ink is supplied to the recording head, the driving mechanism moves the pressing portion in the one direction, and when the ink is filled in the casing of the ink supply portion, the driving mechanism The image forming apparatus according to claim 1 , wherein the image forming apparatus is moved in the other direction to the origin. The ink filter, the image forming apparatus according to claim 1 or 2, characterized in that it is constituted by a mesh member of SUS.

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