JP5073422B2 - Tube pump and image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus including a tube pump and a recording head for discharging droplets.

  As an image forming apparatus such as a printer, a facsimile machine, a copying machine, or a combination of these, an ink jet recording apparatus or the like is known as an image forming apparatus of a liquid discharge recording method using a recording head for discharging a recording liquid droplet, for example. . In this liquid discharge recording type image forming apparatus, a recording liquid, for example, ink droplets, is transported from a recording head (not limited to paper, including OHP, and ink droplets, other liquids can be attached) This is also used as a synonym for image formation (recording, printing, printing, printing) by discharging onto a recording medium or recording medium, recording paper, recording paper, etc.). And a serial type image forming apparatus that forms an image by ejecting droplets while the recording head moves in the main scanning direction, and forms an image by ejecting droplets without moving the recording head There is a line type image forming apparatus using a line type head.

  In the present application, “image forming apparatus” means an apparatus that forms an image by discharging liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc. "Image formation" is not only the application of images with meanings such as characters and figures to the medium, but also the addition of images with no meaning such as patterns to the medium (simply applying droplets to the medium) Also means landing). “Ink” means ink, recording liquid, fixing treatment liquid, liquid, and the like, and is not particularly limited as long as it is a liquid capable of forming an image.

  In an image forming apparatus including a recording head that discharges such droplets, a maintenance / recovery mechanism that maintains and recovers the performance of the recording head that discharges ink is provided, and the nozzle surface of the recording head (surface on which the nozzle is formed). Is sealed with a cap member, and a suction pump composed of a tube pump connected to the cap member is driven to forcibly discharge ink from the nozzles of the recording head.

  The tube pump includes a housing in which an elastic tube is disposed along an arcuate inner wall surface, a rotating member that is rotatably supported with respect to the housing, and an elastic tube that is rotatably supported by the rotating member. And a pressing member that moves along a guide groove provided in the rotating member between a pressing position that presses the elastic tube and a pressing position of the elastic tube, and the rotating member rotates in one direction so that the elasticity by the pressing member The tube's pressing location moves to reduce the internal pressure on the upstream side to generate a negative pressure in the flow path of the elastic tube, and the liquid in the flow path of the elastic tube is sucked from one end side and discharged to the other end side. It is.

  By the way, in the maintenance and recovery mechanism in the above-described image forming apparatus, it is known that a tube pump is used as a suction pump, and that the cap member is moved up and down and the suction pump is driven by a single drive motor.

  In this case, when the tube pump (suction pump) rotates in the reverse direction (direction in which the cap member is moved up and down), the pressing member moves to the release position and does not crush the tube. When switching from normal rotation to reverse rotation, a slight time difference occurs until the pressing member is released (the tube is not crushed) after the rotating member is reversed due to a time lag or the like. There is a problem that the tube is crushed and the ink flows backward as a result.

Thus, for example, Patent Document 1 describes using a spring, a lever, a cam, and the like to prevent a reverse flow of ink when entering a reverse operation from a normal operation (suction operation).
Japanese Patent No. 3664213

In Patent Document 2, the pressure member is always in a pressed state, and when the cap is moved up and down, a one-way clutch is used to prevent the pump rotation member from rotating in the reverse direction, thereby preventing the back flow of ink. Is described.
Japanese Patent No. 2722289

In addition, in Patent Document 3, for the purpose of preventing the generation of abnormal noise when the pressing member is released from the tube, the movement of the pressing member in the circumferential direction is restricted, and the restriction of rotating coaxially with the rotating member. It is described that a plate is provided.
JP 2007-146665 A

  However, in the configuration described in Patent Document 1 described above, a spring, a lever, a cam, and the like are used to cancel the ink backflow, and there is a problem that the configuration is complicated and the cost is increased. . Further, in the configuration described in Patent Document 2, since the pressing member always crushes the tube, the durability of the tube is lowered, and the ink is fixed at the crushed portion of the tube. There is a problem that it may occur.

  The present invention has been made in view of the above problems, and an object of the present invention is to prevent ink backflow in a tube pump with a simple configuration.

In order to solve the above problems, the tube pump according to the present invention is:
A housing in which an elastic tube is arranged in an arc along the inner wall surface;
A rotating member rotatably held with respect to the housing;
A pressing supported rotatably by the rotating member and guided so as to be movable between a pressing position for pressing the elastic tube and a releasing position for releasing the pressing along a guide groove provided in the rotating member. Members,
The rotating member is rotatable coaxially with the rotating member, and the rotation of the pressing member with respect to the rotating member is restricted when the rotating member switches from rotating in the direction in which the pressing by the pressing member is performed to rotating in the reverse direction. And one pressing member release auxiliary plate
The pressing member release auxiliary plate is
Relative rotation within a predetermined range with the rotating member;
The outer peripheral portion has an arm portion that is slidably in contact with the inner wall surface of the housing while receiving frictional resistance ,
The arm portion is expanded in the outer circumferential direction and can move with elasticity in the outer circumferential direction, and the sliding surface of the arm portion contacts the inner wall surface of the housing in the outer circumferential direction,
A configuration is provided in which the rotation direction of the rotation member is switched from the suction direction to the non-suction direction, and the pressing member moves to the release position side, and has a restricting portion with which the support shaft of the pressing member abuts . .

  An image forming apparatus according to the present invention includes a recording head that discharges droplets and a maintenance and recovery mechanism that includes the tube pump according to the present invention that maintains and recovers the recording head.

According to the tube pump of the present invention, it is prevented to rotate the pressing member in the opposite direction when switched the rotation direction of the rotary member can prevent backflow of ink with a simple structure.

  According to the image forming apparatus according to the present invention, since the tube pump according to the present invention is provided, the backflow of ink is prevented, and a stable recording head maintenance and recovery operation can be performed.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. An example of an image forming apparatus according to the present invention will be described with reference to FIGS. 1 is an overall configuration diagram of the image forming apparatus, FIG. 2 is an explanatory diagram on the right side of FIG. 1, FIG. 3 is an explanatory perspective view of a recording unit of the apparatus, and FIG. 4 is a bottom view of a carriage of the apparatus. FIG.

  The image forming apparatus is a copying apparatus. The apparatus main body 1 includes an image reading unit 2 such as a scanner for reading an original image, a recording unit 3 for forming an image on a recording medium (hereinafter referred to as “paper”) P, and a recording. The unit 3 includes a paper feed cassette unit 4 that feeds the paper P. Then, the paper P stored in the paper feed cassette unit 4 is separated and fed one by one by the paper feed roller 5 and the separation pad, and conveyed to the printing unit 10 through the conveyance path 7 to record a required image. The paper P on which the image is formed passes through the paper discharge path 8 and is discharged and stacked on the paper discharge stack unit 9.

  Here, as shown in FIG. 3, the printing unit 10 holds a carriage 23 by a carriage guide (guide rod) 21 and a guide stay (not shown) so as to be movable in the main scanning direction, and a driving pulley by a main scanning motor 27. The moving scanning is performed in the main scanning direction via a timing belt 30 spanned between 28 and the driven pulley 29.

  On the carriage 23, a recording head 24k composed of a liquid ejection head for ejecting black (K) ink and 1 each for ejecting cyan (C) ink, magenta (M) ink, and yellow (Y) ink, respectively. The recording heads 24c, 24m, and 24y (which are referred to as “recording head 24” when they are not distinguished or collectively referred to) are mounted.

  As shown in FIG. 4, each recording head 24 has two nozzle rows 32 in which a plurality of nozzles 31 for discharging droplets are arranged in a row, and the nozzle rows 32 are arranged in the main scanning direction (of the carriage 23). The carriage 23 is mounted with a surface (referred to as a nozzle nozzle surface 31a) on which the nozzle 31 is formed facing downward so as to be in a direction orthogonal to the movement direction. Each recording head 24 is supplied with ink of a required color from an ink cartridge 26.

  The recording head 24 uses a piezoelectric element as a pressure generating means (actuator means) for pressurizing the ink in the ink flow path (pressure generation chamber) to deform the vibration plate that forms the wall surface of the ink flow path. A so-called piezo type that discharges ink droplets by changing the volume in the flow channel, or discharges ink droplets with a pressure generated by heating the ink in the ink flow channel using a heating resistor to generate bubbles. The so-called thermal type, the diaphragm that forms the wall surface of the ink flow path and the electrode are placed opposite to each other, and the diaphragm is deformed by the electrostatic force generated between the vibration plate and the electrode, thereby the ink flow path inner volume It is possible to use an electrostatic type or the like that discharges ink droplets by changing the above.

  An endless transport belt 35 that transports the paper P by electrostatic adsorption or the like is disposed below the carriage 23. The conveyor belt 35 is wound between the driving roller 36 and the driven roller 37 and moves around, thereby conveying the paper P in a direction orthogonal to the main scanning direction.

  Further, as shown in FIGS. 2 and 3, a maintenance / recovery mechanism (device) 38 for maintaining and recovering the nozzle state of the recording head 24 is disposed in the non-printing area on one side of the carriage 23 in the scanning direction. An empty discharge receiving member 39 for empty discharge is disposed in the non-printing area on the other side in the scanning direction.

  The maintenance / recovery mechanism 38 includes a plurality of cap members 41 (suction cap 41a and three moisturizing caps 42b) for capping each nozzle surface 31a of the recording head 24, and a wiping member for wiping the nozzle surface 31a of the recording head 24. A wiper blade 42 and an idle discharge receiver 43 are arranged. A suction pump 45 using a tube pump according to the present invention is connected to the suction cap 41a, and is discharged from the suction pump 45 through a discharge tube 46 to a waste liquid container 40 containing waste ink disposed on the lower side. ing. The empty discharge receiving member 39 has four openings 39a.

Next, a portion for performing head suction (operation for forcibly discharging ink from the nozzles) in the maintenance / recovery mechanism 38 will be described with reference to FIG.
When the ink in the nozzle 31 of the recording head 24 becomes thickened and the ink droplets cannot be ejected normally or at a predetermined timing, the nozzle surface 31a of the recording head 24 is sealed with the suction cap 41a, and the suction pump 45 Is rotated by the motor 47, and the internal space formed by the nozzle surface 31a and the suction cap 41a is set to a negative pressure, whereby ink is sucked and discharged from the nozzle 31. The discharged ink generated at this time is discharged from the suction pump 45 to the waste liquid container 40 as waste liquid.

  The tube pump according to the first embodiment of the present invention constituting the suction pump 45 will be described with reference to FIGS. 6 is an exploded perspective view of the tubing pump, FIG. 7 is a front view of the tubing pump in the suction state, FIG. 8 is a front view of the same with the pressing member releasing auxiliary member removed, and FIG. FIG. 10 is an explanatory front view of the tubing pump in a non-suction state, FIG. 10 is an explanatory front view of the tubing pump with the auxiliary member releasing auxiliary member removed, and FIG. 11 is an explanatory front view of the auxiliary pressing member releasing auxiliary member of the tubing pump.

  This tubing pump 100 has a pump housing 102 in which an elastic tube 101 is wound in an arc along an inner wall surface, and a rotation that is rotatably arranged around a rotation shaft (pump shaft) 103 as a fulcrum. A pump foil (support plate) 104 as a member, and two rollers (rollers) 106 as pressing members that are rotatably supported by the support plate 104 by a support shaft 105 are provided.

  These rollers 106 and 106 are guided by a guide groove 107 provided in the support plate 104 so as to be movable between a pressing position for crushing the elastic tube 102 and a releasing position for releasing the pressure on the elastic tube 102. It is supported.

  As a result, as shown in FIGS. 7 and 8, when the support plate 104 (pump shaft 103) rotates in the suction direction (this is assumed to be normal rotation), the roller 106 is on the side of the pressure support portion 107a of the guide groove 107. The elastic tube 101 is rotated according to the support plate 104 while crushing the elastic tube 101, and the ink and the like inside the elastic tube 102 are discharged in the rotation direction of the support plate 104.

  On the other hand, as shown in FIGS. 9 and 10, when the support plate 104 (pump shaft 103) rotates in the non-suction direction (this is reversed), the roller 106 is in the inner circumferential direction of the guide groove 107. Therefore, the elastic tube 101 is rotated according to the support plate 104 without crushing the elastic tube 101, and the ink inside the elastic tube 102 is not discharged in the discharge direction.

  In this way, the amount of biting of the roller 106, which is a pressing member, to the tube 101 is changed depending on the rotation direction of the pump shaft 103 (support plate 104), and the two modes of suction and non-suction can be used. In this case, the pressing member (roller 106) must be instantaneously separated (released) from the tube 101 when changing from the suction direction to the non-suction direction. The pressing member 106 rotates together with the support plate 104, and the pressing member 106 releases the pressing member 106 after the predetermined angle pressing member 106 crushes the tube 101. As a result, the ink in the tube 101 flows backward, causing the nozzle to go down. Connected. Here, in order to prevent the backflow of the ink, if the shape of the guide groove 107 is a shape in which the pressing member 106 is suddenly dropped from the pressing support portion 107a to the pressing and retracting position 107b, the pressing member 106 is moved to the retracting position in the suction direction. It is released and cannot be sucked.

  Therefore, the tube pump 100 can rotate coaxially with the support plate 104 that is a rotating member, and when the support plate 104 is switched from rotation in the direction in which the pressing by the pressing member 106 is performed to rotation in the reverse direction. A release assisting plate 110 that is a pressing member releasing assisting member that restricts the accompanying movement of the pressing member 106 with respect to the support plate 104 is provided.

  The release auxiliary plate 110 is rotatably attached to the pump shaft 103. The release assisting plate 110 includes an engaging portion 110a having a regulating surface 111 with which the support shaft 105 of the pressing member 106 abuts when the support plate 104 is switched from the suction direction to the non-suction direction.

In addition, the release assisting plate 110 has a portion (referred to as an arm portion) 112 that is slidably in contact with the inner wall surface 102a of the pump housing 102 while receiving frictional resistance. This arm portion 112 by the sliding surface 112a in expanded state in the outer circumferential direction contacts the inner wall surface 102a of the housing 102, is rotatable relative to the inner wall surface 102a of the pump housing 102, the rotational direction of the support plate 104 Even if is switched, the direction of rotation does not change instantaneously.

  Further, the release assisting plate 110 is provided with an engagement surface 113 on the side facing the contact surface 111a in order to suppress the sudden movement of the pressing member 106 toward the pressing release position 107a.

Furthermore, the release auxiliary plate 110 in the circumferential direction to form the elongated hole 114, into engagement with the pin 108 provided on the support plate 104, which suppresses the relative rotation range with respect to the support plate 104 of the release auxiliary plate 111. Without means for inhibiting the rotation of the release assisting plate 111, when the support plate 104 rotates in the suction direction, the regulating surface 111 of the release assisting plate 110 comes into contact with the support shaft 105 of the roller 106, and Rotation is impeded. If the roller 106 does not rotate, friction may occur between the roller 106 and the tube 101 when the roller 106 crushes the tube 101 during suction, and the tube 101 may be damaged. Therefore, when the support plate 104 rotates in the suction direction, the restriction surface 111 of the release assisting plate 110 is prevented from coming into contact with the support shaft 105 of the roller 106.

Since it comprised in this way, as shown in FIG. 12, when the rotation direction of the support plate 104 switches from the suction direction (solid arrow direction: forward rotation) to the non-suction direction (broken arrow direction: reverse rotation), the release auxiliary plate Since the sliding contact surface 112a of the arm portion 112 of 110 is in contact with the inner wall surface 102a of the housing 102 in a state of receiving frictional resistance, the support plate 104 (pump shaft 103) rotates in the reverse direction. But it doesn't rotate in the opposite direction at the same time.

That is, as shown in FIG. 13, the guide groove 107 moves in the direction of arrow A due to the rotation of the support plate 104, but the release assisting plate 110 is stopped, so that the support shaft 105 of the roller 106 is placed on the regulating surface 111. It comes into contact, is released from the pressed position, and instantaneously moves in the direction indicated by the arrow B and moves away from the tube 101. Thereby, the backflow of ink is prevented.

  Thus, when the rotation member is switched from the rotation in the direction in which the pressing by the pressing member is performed to the rotation in the reverse direction, the pressing member releasing auxiliary member that regulates the rotation of the pressing member with respect to the rotating member is provided. Even when the rotation direction of the rotating member is switched, the pressing member is prevented from rotating in the reverse direction, and the backflow of ink can be prevented with a simple configuration of adding the pressing member releasing auxiliary member.

Next, a tube pump according to a second embodiment of the present invention will be described with reference to FIGS. 14 is an explanatory front view of the tube pump, and FIG. 15 is an explanatory front view of the pressing member releasing auxiliary member.
In contrast to the restriction surface 111 of the release auxiliary plate 110 of the first embodiment provided with the engaging portion 111a along the radial direction of the support plate 104, the restriction surface 111 of the release auxiliary plate 110 is provided in the second embodiment. An engaging portion 111a that is inclined inward in the circumferential direction is provided.

Thereby, when the support shaft 105 of the roller 106 switches the rotation direction of the support plate 104 from the suction direction to the non-suction direction, the support surface 104 contacts the restriction surface 111 when the support shaft 105 contacts the restriction surface 111. By being pushed in the inner circumferential direction, it is smoothly and instantaneously separated from the tube 101 without generating abnormal noise due to contact with the regulating surface 111.

Next, a tube pump according to a third embodiment of the present invention will be described with reference to FIG. FIG. 16 is an explanatory perspective view of the tube pump attached to the frame member.
In this embodiment, the sliding contact surface 112a of the auxiliary release plate 110 is slidably contacted with the sliding surface 121 formed by the frame member (mounting member) 120 to which the tube pump 100 is mounted while receiving frictional resistance. Yes.

Next, a tube pump according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 17 is an exploded perspective view of the tube pump.
In this embodiment, the engagement claw 130 provided on the release auxiliary plate 110 is detachably engaged with the engagement hole 131 provided on the support plate 104 so that the release auxiliary plate 110 is detachable from the pump shaft 103. This facilitates recycling of the release assisting plate 110.

1 is a schematic configuration diagram illustrating an overall configuration of an image forming apparatus to which the present invention is applied. FIG. 2 is an explanatory diagram on the left side of FIG. It is a perspective explanatory view of a printing part of the same device. It is perspective explanatory drawing seen from the bottom face of the carriage of the same apparatus. It is explanatory drawing with which it uses for description of head attraction | suction. It is a disassembled perspective explanatory drawing of the tube pump which concerns on 1st Embodiment of this invention. It is front explanatory drawing of the suction state of the tubing pump. It is front explanatory drawing in the state which removed the pressing member cancellation | release auxiliary member similarly. It is front explanatory drawing of the non-suction state of the tubing pump. It is front explanatory drawing in the state which removed the pressing member cancellation | release auxiliary member similarly. It is front explanatory drawing of the press member cancellation | release auxiliary member of the tubing pump. It is front explanatory drawing with which it uses for description at the time of the rotation direction switching of the tubing pump. It is a principal part expansion explanatory drawing similarly. It is front explanatory drawing of the tube pump which concerns on 2nd Embodiment of this invention. It is front explanatory drawing of a pressing member cancellation | release auxiliary member similarly. It is a perspective explanatory view in the state where a tube pump concerning a 3rd embodiment of the present invention was attached to a frame member. It is a disassembled perspective explanatory drawing of the tube pump which concerns on 4th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Apparatus main body 2 ... Image reading part 3 ... Recording part 4 ... Paper feed cassette part P ... Paper (recording medium)
10 ... Printing unit (engine unit)
DESCRIPTION OF SYMBOLS 23 ... Carriage 24 ... Recording head 31 ... Nozzle 31a ... Nozzle surface 32 ... Nozzle row 35 ... Conveyance belt 38 ... Maintenance recovery mechanism part 41 ... Cap member 42 ... Wiper member 43 ... Empty discharge receptacle 45 ... Suction pump 100 ... Tube pump 101 ... Elastic tube 102 ... Pump housing 103 ... Pump shaft 104 ... Support plate (rotating member 105 ... Guide shaft 106 ... Roller (pressing member)
110 ... Release auxiliary plate (Pressing member release auxiliary member 111 ... Restricting surface 112a ... Sliding contact surface

Claims (2)

A housing in which an elastic tube is arranged in an arc along the inner wall surface;
A rotating member rotatably held with respect to the housing;
A pressing supported rotatably by the rotating member and guided so as to be movable between a pressing position for pressing the elastic tube and a releasing position for releasing the pressing along a guide groove provided in the rotating member. Members,
The rotating member is rotatable coaxially with the rotating member, and the rotation of the pressing member with respect to the rotating member is restricted when the rotating member switches from rotating in the direction in which the pressing by the pressing member is performed to rotating in the reverse direction. And one pressing member release auxiliary plate
The pressing member release auxiliary plate is
Relative rotation within a predetermined range with the rotating member;
The outer peripheral portion has an arm portion that is slidably in contact with the inner wall surface of the housing while receiving frictional resistance ,
The arm portion is expanded in the outer circumferential direction and can move with elasticity in the outer circumferential direction, and the sliding surface of the arm portion contacts the inner wall surface of the housing in the outer circumferential direction,
A regulating portion on which a support shaft of the pressing member abuts when the rotating direction of the rotating member is switched from the suction direction to the non-suction direction and the pressing member moves to the release position side is provided. And tube pump. An image forming apparatus comprising a recording head for ejecting droplets and a maintenance / recovery mechanism for maintaining and recovering the recording head, wherein the maintenance / recovery mechanism comprises the tube pump according to claim 1. Image forming apparatus.

Images