JP2012097632A - Tube pump and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tube pump in which a rotational load is not applied more than necessary on a press roller while a compact and simple structure generates minimum required pressure for pressing a tube to be secured without increasing cost, and to provide an ink-ejecting type image forming device having the tube pump.SOLUTION: The tube pump using for the ink-ejecting type image forming device which supplies or sucks ink includes: the hollow tube (102) serving as a channel of the ink and having elasticity; and the press roller 21 pressing the tube by rotating. A hollow gap 21b is formed inside a cross section of a pressing part 21c of the press roller 21 which abuts against the tube and presses the tube.

Description

  The present invention relates to an ink discharge method including a recording head for discharging ink, such as a printer, a facsimile machine, a copying machine, a plotter, and a composite machine thereof (here, the ink discharge method includes an ink jet method, a liquid, The same applies to the image recording apparatus in which images are recorded by ejecting foamy and colloidal inks, and the same applies to the image forming apparatus in detail.・ It relates to tube pumps used for discharge and suction.

Ink ejection type image forming apparatuses are provided with a recording head maintenance mechanism because ink viscosity may increase due to evaporation of the ink solvent in the nozzles of the recording head and ink ejection failure may occur. This head maintenance mechanism usually includes a cap that covers the nozzles of the recording head, and a suction pump that communicates with the cap and generates a negative pressure in the cap. The suction pump sucks the thickened ink from the nozzles. In this way, ink discharge defects are reduced.
The ink ejection type image forming apparatus also includes a supply pump for supplying ink from the ink cartridge to the recording head.

  Such suction pumps and supply pumps are conventionally flexible because they have a relatively simple structure and are easy to miniaturize, and they do not cause contamination in the mechanism for sucking, supplying and discharging ink. A tube pump including a tube made of a material and a pressing roller that sequentially presses the tube while moving along the longitudinal direction of the tube is used (for example, Patent Documents 1 and 2).

  In the case of a structure in which ink is supplied from the main tank to the head tank by such a tube pump, when the pump is stopped, the tube is pressed by the pressing roller, and the flow path is shut off, so that the inside of the head tank is In order to block the flow path of the tube and withstand negative pressure in this way, it is necessary to prevent the natural supply of ink from the main tank due to the negative pressure of the main tank and to prevent the pressure of the head tank from changing. While pressing the tube over the wall thickness, the amount of pressing of the tube had to be strictly controlled. Therefore, in consideration of variations in the pressing amount of the pressing roller, that is, in consideration of dimensional tolerances and assembly tolerances of various parts constituting the tube pump, the tube support surface and the pressing roller so that the pressing amount is on the safe side. Therefore, there is a problem that the amount of crushing of the tube increases, and the rotational torque of the pressing roller is unnecessarily loaded.

  In order to solve such a problem, Patent Document 3 describes a tube through which a liquid flows, a tube support surface that regulates the outer diameter of the tube in an arc shape, and a part of the tube being pressed against the tube support surface while rotating. The tube support surface is provided with a plurality of protrusions, and when the pump is stopped, the tube is pressed against the tube support surface and at least one of the plurality of protrusions and the pressure roller, thereby blocking the tube flow path. It is characterized by the fact that the flow path of the tube can be shut off reliably even if the rotation of the pump stops when the pressure roller comes to the position, preventing the natural supply of liquid without sacrificing the rotational torque The tube pump which can do is disclosed (refer FIG. 5 etc. of patent document 3).

Patent Document 4 discloses a tube pump which is mounted on an ink jet image forming apparatus and has a structure in which a pressing roller is pressed against a tube side by a roller bearing and a spring (see FIGS. 2, 3 and the like of Patent Document 4). ).
However, each of the tube pumps described in Patent Documents 3 and 4 has a complicated and large configuration, which increases the number of parts and increases the assembly work, which is expensive. .

  Furthermore, Patent Document 5 includes a discharge tube and a roller that sequentially presses the discharge tube while moving along the longitudinal direction of the discharge tube, and the roller includes an inelastic layer that does not have elasticity, and It is composed of an elastic layer having elasticity, and when pressing the tube with a roller, the variation in pressing force applied to the tube is absorbed by the elastic body of the roller, so without increasing the number of parts, There has been disclosed a tube pump capable of reducing variations in pressing force applied to the tube with a simple configuration (see FIG. 3 of Patent Document 5).

  However, although the tube pump described in Patent Document 5 can reduce the variation in the pressing force of the roller by the elastic layer, the elastic layer has a large dimensional tolerance and there is an accuracy error such as an installation interval. Not only is there a problem that the roller driving mechanism is loaded more than necessary, but since the roller has a two-layer structure, it cannot be denied that the cost is increased.

  Therefore, in order to solve the above-described problems, the present invention rotates the pressure roller more than necessary while ensuring the minimum pressing force required to press the tube without increasing the cost with a small and simple configuration. It is an object of the present invention to provide a tube pump that is not subjected to a load, and an ink discharge type image forming apparatus including the tube pump.

  In order to solve the above-mentioned problem, the invention described in claim 1 includes a hollow tube having elasticity that serves as an ink flow path, and a pressing roller that presses the tube by rotating the tube. In a tube pump used in an ink ejection type image forming apparatus that supplies or sucks ink, the pressing roller has a hollow space formed inside a cross section of a pressing portion that contacts and presses the tube. It is characterized by being.

  According to a second aspect of the present invention, in the tube pump according to the first aspect, the pressing roller is an eccentric roller having an eccentric rotation shaft.

  According to a third aspect of the present invention, in the tube pump according to the first or second aspect, the pressing roller has a convex portion protruding in a radial direction of the gap portion, and the convex portion is an edge of the gap portion. The pressing portion is configured not to bend more than a certain distance by contacting with.

  According to a fourth aspect of the present invention, in the tube pump according to any one of the first to third aspects, an elastic material is inserted into the gap.

  According to a fifth aspect of the present invention, in the tube pump according to any one of the second to fourth aspects, the curvature of the outer peripheral surface of the pressing roller is partially reduced, and the outer roller is free to play outside thereof. The tube is fitted, and the tube is pressed through the outer roller.

  A sixth aspect of the present invention is the tube pump according to the first aspect, wherein the pressing roller is a roller in which a rotating shaft having a plurality of pressing rollers attached to an outer peripheral surface is not eccentric, and the pressing roller A hollow portion that is hollow is formed inside the cross section of the portion to which is attached.

  The invention according to claim 7 is an ink cartridge that stores ink, a carriage that is movable in the main scanning direction, a recording head that is mounted on the carriage and discharges ink onto paper, and is sent from the ink cartridge. A head tank that temporarily stores the received ink and sends it to the recording head; and a pump that communicates with the ink cartridge and the head tank and supplies ink to the head tank or sucks ink from the head tank. An ink ejection type image forming apparatus is characterized in that the tube pump according to any one of claims 1 to 6 is mounted as the pump.

  The present invention is as described above, and according to the invention of claim 1, a hollow tube having elasticity that serves as an ink flow path, and a pressing roller that presses the tube by rotating the tube, In the tube pump used in an ink ejection type image forming apparatus that supplies or sucks ink, the pressing roller has a hollow space inside the cross section of the pressing portion that contacts and presses the tube. Since it is formed, it is possible to continue pressing against the restoring force of the tube with the pressing roller until the pressing portion bends, and there is an accuracy error in the installation position of the rotating shaft of the pressing roller. However, since the hollow part which became hollow inside the cross section of a press part is formed, an unnecessary rotational load is not applied to the drive mechanism of a press roller because a press part bends. Therefore, it is possible to provide a tube pump in which a rotational load is not applied more than necessary while securing a minimum pressing force required to press the tube without increasing the cost with a small and simple configuration.

  According to a second aspect of the present invention, in the tube pump according to the first aspect, the pressing roller is an eccentric roller having an eccentric rotation shaft. This can be achieved using a core roller.

  According to a third aspect of the present invention, in the tube pump according to the first or second aspect, the pressing roller has a convex portion protruding in a radial direction of the gap portion, and the convex portion is the gap portion. Since the pressing portion is configured not to bend more than a certain distance by abutting with the edge, the deflection of the pressing portion is defined to be not more than a certain distance by the protruding height in the radial direction of the convex portion in addition to the above-described effects. It is possible to prevent the pressing portion from being bent too much to ensure the necessary amount of pressing of the tube.

  According to a fourth aspect of the present invention, in the tube pump according to any one of the first to third aspects, since an elastic material is inserted into the gap portion, in addition to the operational effects, an elastic force is provided. The minimum pressing force required to press the tube against the restoring force of the tube it has can be defined by the repulsive force of the elastic material inserted into the gap, making it easy to secure the required pressing force Become.

  According to a fifth aspect of the present invention, in the tube pump according to any one of the second to fourth aspects, the curvature of the outer peripheral surface of the pressing roller is partially reduced, and the outer roller is disposed outside the pressing roller. Since the tube is loosely fitted and the tube is pressed via the outer roller, in addition to the above-described effects, the outer portion can be loosely fitted as well as ensuring the minimum pressing force without excessively bending the pressing portion. Therefore, the tube can be pressed without being worn, and the durability of the tube pump is improved.

  According to invention of Claim 6, in the tube pump of Claim 1, the said pressing roller is a roller with which the rotating shaft with which the several pressing roller was attached to the outer peripheral surface is not eccentric, Since a hollow space is formed inside the cross section of the portion to which the pressing roller is attached, the above-mentioned effect can be achieved without wearing the tube using a roller whose rotating shaft is not eccentric. it can.

  According to the seventh aspect of the invention, an ink cartridge that stores ink, a carriage that is movable in the main scanning direction, a recording head that is mounted on the carriage and discharges ink onto a sheet, and the ink cartridge A head tank that temporarily stores the sent ink and sends it to the recording head; a pump that communicates with the ink cartridge and the head tank, supplies ink to the head tank, or sucks ink from the head tank; Since the tube pump according to any one of claims 1 to 6 is mounted as the pump in the ink ejection type image forming apparatus, the function and effect are exhibited in the ink ejection type image forming apparatus. Can do.

1 is an external perspective view showing a front surface, a right side surface, and an upper surface of an image forming apparatus according to an embodiment. FIG. 2 is a configuration explanatory diagram showing an internal configuration of the image forming apparatus according to the embodiment from a left side surface. It is a top view which shows the structure of the principal part of an image forming apparatus same as the above in the horizontal cross section. It is a configuration explanatory view showing a schematic configuration of a tube pump according to Conventional Example 1. It is a configuration explanatory view showing a schematic configuration of a tube pump according to Conventional Example 2. FIG. 3 is an explanatory diagram illustrating a configuration of a pressing roller according to Embodiment 1 in a cross section perpendicular to a rotation axis. FIG. 5 is a configuration explanatory view showing a configuration of a pressing roller according to Embodiment 2 in a cross section perpendicular to a rotation axis. 10 is a perspective view showing a pressing roller according to Embodiment 3. FIG. FIG. 10 is a configuration explanatory view showing a configuration of a pressing roller according to Embodiment 4 in a cross section perpendicular to a rotation axis. FIG. 10 is a configuration explanatory view showing a configuration of a pressing roller according to Embodiment 5 in a cross section perpendicular to a rotation axis. FIG. 10 is a configuration explanatory view showing a configuration of a pressing roller according to Embodiment 6 in a cross section perpendicular to a rotation axis. FIG. 10 is a configuration explanatory view showing a configuration of a pressing roller according to Embodiment 7 in a cross section perpendicular to a rotation axis. It is explanatory drawing which shows the state before the press part of the press roller which concerns on Embodiment 8 begins to bend in a cross section perpendicular | vertical to a rotating shaft. It is explanatory drawing which shows the state which the inner peripheral surface of an outer roller is contacting the outer peripheral surface of a press roller same as the above in the cross section perpendicular | vertical to a rotating shaft. FIG. 10 is an explanatory diagram showing a configuration of a pressing roller according to Embodiment 9 in a cross section perpendicular to a rotation axis.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Overall configuration of image forming apparatus)
First, the overall configuration of the image forming apparatus according to the embodiment of the present invention will be described with reference to FIGS. Reference numeral 1 in the figure denotes an ink jet type color printer exemplified as an embodiment of an image forming apparatus according to the present invention. The color printer 1 is a substantially box-shaped device which is a casing of the entire image forming apparatus. A main body 1a, a cartridge loading section 2 for projecting forward to the right side of the front surface of the apparatus main body 1a, a cartridge loading section 2 for containing an ink cartridge described later, and a top surface of the cartridge loading section 2 are provided. The operation display unit 3 responsible for the operation and display function, and the upper part in the apparatus main body 1a are provided. Paper (material is not particularly limited, and can be fed including copy paper, OHP resin sheet, cardboard, postcard, etc.) A sheet-like member that can be attached and impregnated with ink, the same applies hereinafter), and an image forming unit 5 that forms an image and a lower portion of the apparatus main body 1a. A paper feeding unit 6 that feeds paper and a lower side of the image forming unit 5, a paper transporting unit 7 that transports paper from the paper feeding unit 6 to the image forming unit 5, and a paper feeding unit 6 that is provided above the paper feeding unit 6 A paper discharge unit 8 that discharges paper from the unit 7 and stocks it is provided.

  The cartridge loading portion 2 is a portion in which a plurality of vertically long and narrow rectangular parallelepiped ink cartridges are loaded side by side. A front cover 2a is attached to the front portion so as to be freely opened and closed. Each ink cartridge is attached to and detached from the cartridge loading unit 2 by inserting and removing the ink cartridge in the front-rear direction. The plurality of ink cartridges 2K, 2C, 2M, and 2Y are inks of each color of cyan (C), magenta (M), yellow (Y) that are three primary colors of chromatic color, and black (K) that is an achromatic color. Are accommodated by color and have a function as a main tank of ink for forming an image.

  In addition, the operation display unit 3 is provided with remaining amount display units 3K, 3C, 3M, and 3Y that display the remaining ink levels of the ink cartridges 2K, 2C, 2M, and 2Y at the near end and the end. A button 31, a paper feed / print resume button 32, a cancel button 33, and the like are provided.

  The image forming unit 5 includes a carriage 50 that forms an image on a sheet by ejecting ink from a recording head described later. The carriage 50 is slidably supported on the guide rod 51 by a guide rod 51 and a stay 52 made of a round bar extending over the left and right side surfaces of the apparatus main body 1a. Is driven via the timing belt, and moves in the main scanning direction in the drawing to form an image on a sheet by ejecting the corresponding ink from the recording heads 53K, 53C, 53M, 53Y provided for each ink color. have.

  These recording heads 53K, 53C, 53M, and 53Y are so-called ink jet heads each having a driver IC and a nozzle (not shown) connected to a control unit (not shown) and a harness hc (flexible print cable). The ink is ejected downward from the nozzles by applying energy to each color ink supplied from the head tanks 54K, 54C, 54M, 54Y by a piezoelectric actuator (not shown) such as a piezoelectric element.

  In place of this piezoelectric actuator, a thermal actuator that uses a phase change caused by film boiling of a liquid using an electrothermal transducer such as a heating resistor, a shape memory alloy actuator that uses a metal phase change caused by a temperature change, an electrostatic force It is possible to apply other energy generating means such as an electrostatic actuator to be used.

  The head tanks 54K, 54C, 54M, and 54Y communicate with the corresponding ink cartridges 2K, 2C, 2M, and 2Y through the supply tube 2b, and the ink cartridges 2K, each of which has the ink of each color as a main tank by using the pump unit 2c as a power source. The system is supplied from 2C, 2M, 2Y. The supply tube 2b is fixed to the back surface of the apparatus main body 1a by a fixing rib 2d and is fixed to the main body of the carriage 50 by a fixing rib 2e so that the carriage 50 does not come off because the carriage 50 moves.

  The paper feed unit 6 includes a paper feed tray 60 mounted on the lower front surface of the apparatus main body 1a, a bottom plate 61 that is swingably attached to the paper feed tray 60 and places paper while being biased upward. Provided above the rear end of the bottom plate 61, the vertical cross section for feeding paper by being driven to rotate is disposed opposite to the half-moon-shaped paper feeding roller 62 and the peripheral surface of the paper feeding roller 62, and a coil spring or the like. A separation pad 63 made of a material having a large coefficient of friction, which is urged by the urging means to the paper feed roller 62, and the like. It is a mechanism for feeding to a later-described transport belt 70 while separating the sheets one by one.

  The paper transport unit 7 electrostatically discharges the paper fed from the paper feed unit 6 up to a print area in which the carriage 50 can move and the paper can face below the nozzles of the recording heads 53K, 53C, 53M, and 53Y. A conveyance belt 70 for adsorbing and conveying is provided. The conveyance belt 70 is an endless belt stretched between a conveyance roller 71 that is a driving roller and a tension roller 72 that applies a predetermined tension to the conveyance belt 70. The conveyance belt 70 rotates in the clockwise direction in FIG. It is rotationally driven in the sub-scanning direction). A charging roller 73 as a charging unit for electrostatically adsorbing the paper is provided on the outer peripheral surface of the conveyance belt 70 so as to be in contact with the conveyance belt 70 and driven to rotate. A printing guide 74 is provided for guiding the conveyance belt 70 so as not to shake in correspondence with the printing area.

  Further, in order to change the direction of the sheet between the paper feeding unit 6 and the conveyance belt 70, the first conveyance guide 75 that changes the direction while guiding the sheet and the outer peripheral surface of the conveyance belt 70 are pressed against each other. A counter roller 76 that sandwiches the paper with the conveyance belt 70 by following rotation, a second conveyance guide 77 that changes direction while guiding the paper, and a tip addition that pressurizes the paper to prevent it from shaking. A pressing member 79 having a pressure roller 78 is provided.

  The paper discharge unit 8 is detachably attached to the apparatus main body 1a, and is transported by a paper discharge tray 80 for stocking sheets on which images are printed by the recording heads 53K, 53C, 53M, and 53Y. A separation claw 81 provided near the end of the direction for separating the paper from the conveying belt 70, a paper discharge roller 82 provided near the separation claw 81 for rotating and discharging the paper, and the paper discharge roller 82 A paper discharge roller 83 that is disposed opposite to and is driven to rotate, and the paper that has been sucked and conveyed by the conveyance belt 70 is separated by a separation claw 81 and sandwiched between a paper discharge roller 82 and a paper discharge roller 83, The paper discharge roller 82 is rotationally driven to discharge the paper to the paper discharge tray 80.

  Further, a duplex unit 90 is detachably attached to the back surface of the apparatus main body 1a of the color printer 1, and the duplex unit 90 takes in paper by reverse rotation of the transport belt 70 (transport roller 71). After that, the sheet is reversed and fed again between the counter roller 76 and the conveying belt 70 to have the function of reversing the sheet in double-sided printing. The upper surface of the duplex unit 90 is a manual feed tray 91, and the manual feed tray 91 has a function of feeding manual paper between the counter roller 76 and the conveyance belt 70 as in the duplex unit 90. Yes.

(Maintenance and recovery device)
Next, a recording head maintenance / recovery device of the color printer 1 will be described mainly with reference to FIG.
As shown in FIG. 3, the state of the nozzles of the recording heads 53K, 53C, 53M, and 53Y is maintained / recovered in one non-printing area in the main scanning direction (right side in the illustrated embodiment) in the apparatus main body 1a. A maintenance / recovery device 10 is provided. The maintenance / recovery device 10 includes a plurality of caps 11 as cap members for capping the nozzles of the recording heads 53K, 53C, 53M, and 53Y, a wiper blade 12 as a blade member for wiping in contact with the nozzle surface, An empty discharge receiver 13 serving as a waste ink receiver for empty discharge for discarding viscous ink, and a wiper as a cleaning member that is integrally formed with the empty discharge receiver 13 and that cleans the thickened ink attached to the wiper blade 12. A cleaner (not shown) and a cleaner roller 14 for pressing the wiper blade 12 at the time of cleaning are provided on the wiper cleaner, and the recording heads 53K, 53C, 53M, 53Y are periodically cleaned to obtain the recording heads 53K, 53C, Ink melt in 53M and 53Y nozzles Ink viscosity rises and an ink ejection failure has the function of preventing the occurrence by evaporation.

  In addition, an empty discharge receiver 15 that receives waste ink when empty discharge is performed during printing is disposed in the non-printing area on the other side in the main scanning direction (on the left side in the illustrated embodiment) in the apparatus main body 1a. The idle discharge receiver 15 is provided with a plurality of openings 16 along the nozzle rows of the recording heads 53K, 53C, 53M, and 53Y.

(Image formation operation and maintenance / recovery operation)
Next, the image forming operation and the maintenance / recovery operation of the color printer 1 will be described with reference to FIGS.
First, the color printer 1 sends out the sheets placed on the sheet feeding tray 60 while separating them one by one by the sheet feeding roller 62 and the separation pad 63. The sheet fed from the sheet feed tray 60 is guided along the first conveyance guide 75, is sandwiched between the conveyance belt 70 and the counter roller 76, and rotates with the rotation of the conveyance roller 71. Further, The conveyance direction of the paper guided by the second conveyance guide 77 and sandwiched between the tip pressure roller 78 and the conveyance belt 70 and sent out from the paper feed tray 60 as the conveyance roller 71 further rotates is substantially the same. The paper is turned 180 ° and the paper reaches the printing area.

  At this time, an alternating voltage in which a positive output and a negative output are alternately repeated is applied to the charging roller 73 from an AC bias supply unit of a control unit (not shown), and the conveyance belt 70 is positively increased in the sub-scanning direction, which is the rotation direction. The negative is charged into an alternating pattern that is alternately charged in a band shape with a predetermined width. When the sheet is fed onto the conveyance belt 70 charged in the alternating pattern in this way, the sheet is electrostatically attracted to the conveyance belt 70.

  In the printing area, the carriage 50 is scanned in the main scanning direction by the control unit based on the main scanning position information by the linear encoder attached to the carriage 50, and the sheet is sucked and stopped by the conveyance belt 70 according to the image signal. The ink is ejected to print (record) one line. Then, after the printing is completed, the conveyor belt 70 is rotated by a predetermined amount corresponding to one line, the paper is fed, and the next line is recorded. When the control unit receives a signal indicating completion of printing or a signal indicating that the trailing edge of the sheet has reached the printing area, the printing operation is terminated and the sheet is discharged onto the discharge tray 80.

  During printing (recording) standby, the carriage 50 moves to the maintenance / recovery device 10, and the nozzles of the recording heads 53K, 53C, 53M, and 53Y are capped by the cap 11 to keep the nozzles wet. Prevents drying out and causing poor discharge. In addition, with the cap 11 capping the recording heads 53K, 53C, 53M, and 53Y, the ink that has been thickened is sucked from a nozzle by a suction / discharge pump (not shown), and the thickened ink and bubbles mixed in the ink are received and discharged. The recovery operation of discharging to 13 is performed. In addition, before printing is started or during printing, an empty discharge operation (maintenance operation) is performed in which ink that does not contribute to printing is discharged from the recording heads 53K, 53C, 53M, and 53Y to the empty discharge receiver 13 and the empty discharge receiver 15. By these maintenance and recovery operations, the stable ink ejection performance of the recording heads 53K, 53C, 53M, and 53Y is maintained.

(Outline of tube pump)
Next, an outline of a tube pump used in the above-described pump unit 2c (see FIG. 3) and the suction / discharge pump of the maintenance / recovery device 10 will be described by exemplifying the tube pumps according to Conventional Examples 1 and 2 shown in FIGS. I will explain. A tube pump 100 according to Conventional Example 1 shown in FIG. 4 has a pump unit 101 that is a base (main body) of the tube pump and moderate elasticity (hardness of about 50 to 65 is preferable) that is an ink flow path. From a hollow tube 102 made of a flexible material, and a pressure roller 105 that supplies ink by pressing the tube 102 against an arcuate tube support surface 103 that is an inner peripheral surface of the pump unit 101. It is configured. The pressing roller 105 is a rotating roller in which a rotating shaft 104 integrally molded from resin is eccentric, and the tube 102 is pressed against the tube support surface 103 of the pump unit 101 by rotating in any of the arrow directions in the figure. By squeezing, the ink in the tube 102 is pushed out and supplied. In the case of suction, the pressure roller 105 is reversely rotated to separate the outer peripheral surface of the pressure roller 105 from the tube support surface 103, thereby generating a negative pressure in the tube 102 using the restoring force of the tube 102, It is configured to suck ink having increased viscosity.

  The difference between the tube pump 100 ′ according to the conventional example 2 shown in FIG. 5 and the tube pump 100 according to the conventional example 1 is that the eccentric pressure roller 105 in the tube pump 100 according to the conventional example 1, In the tube pump 100 ′ according to the second conventional example, the plurality of pressing rollers 106 is that the rotating shaft 104 ′ provided on the outer peripheral surface of the pressing roller is a pressing roller 105 ′ that is not eccentric, and the other is the same. Therefore, the same reference numerals are given and the description thereof is omitted. In the tube pump 100 ′ according to the conventional example 2, when the ink is supplied / discharged, the pressing roller 105 ′ rotates in either direction, so that the pressing roller 106 rotates around the outer peripheral surface of the pressing roller 105 ′. While the tube 102 is pressed against the tube support surface 103 of the pump unit 101 and rotated while being squeezed, the pressure in the tube 102 is changed to supply or discharge ink.

  Such tube pumps 100 and 100 'according to the conventional examples 1 and 2 generate a negative pressure by using a restoring force that returns to the original state after the tube 102 is crushed, so that the pump is stopped. In order to prevent negative pressure from being generated by the restoring force of the tube 102, the flow path of the tube 102 must be blocked, that is, the pressure roller 105, 105 ′ must be kept pressing the tube 102 at at least one point. I must. For this reason, as described in the background art, the pressing amount (pressing force) of the tube 102 must be strictly managed, and the crushing amount of the tube 102 is inevitably increased, and the rotational torque is sacrificed. The problem was unavoidable.

  Therefore, in the present invention, an improvement is made to the pressing roller of the tube pump, and the pressing roller driving mechanism is more than necessary by reducing the variation in the pressing force that presses the tube with the pressing roller while ensuring the minimum pressing force. The load was not applied.

[Embodiment 1]
Next, the configuration of the pressing roller of the tube pump according to the embodiment of the present invention will be described with reference to FIGS. The pressing roller 21 according to the first embodiment shown in FIG. 6 is a pressing roller having a rotating shaft eccentric like the pressing roller 105 according to the conventional example 1, and is different from the pressing roller 105 according to the conventional example 1. In the cross section (axial cross section) perpendicular to the shaft 21a of the roller 21, a hollow portion 21b that is hollow is provided in the inside (portion that does not contact the outer peripheral surface). The crescent shape in which the gap portion is the largest in the central portion of the pressing portion 21c that presses in contact with the tube (see reference numeral 102 in FIGS. 4 and 5), which is the thickest in the radial direction of the roller. It has become.

  As described above, according to the tube pump having the pressing roller 21 according to the first embodiment, since the hollow space 21b is provided, the tube is pressed by the pressing force until the pressing portion 21c is bent. Even if there is an accuracy error in the installation position of the pressure roller 21 such as the distance between the pressure roller 21 and the tube support surface of the pump unit while ensuring the minimum necessary pressing force, there is a gap 21b. For this reason, the pressing portion 21c can be deflected inward to release the stress, and a load is not applied to the drive mechanism of the tube pump more than necessary. Moreover, since it implement | achieves by the simple and cheap structure of providing a space | gap part, it does not raise a cost.

[Embodiments 2 to 5]
Here, the gap 21b described above may be a fan-shaped gap 22b as in the pressing roller 22 according to Embodiment 2 shown in FIG. Further, when the pressing force is too strong, the axial thickness Y of the pressing portion 23c is processed (cut) to provide a tapered surface as in the pressing roller 23 according to the third embodiment shown in FIG. Alternatively, the thickness X in the radial direction of the pressing portion 23c may be thinly formed from the beginning. When the pressing force is too weak, that is, when the pressing portion is bent too much, as in the pressing rollers 24 and 25 according to the fourth and fifth embodiments shown in FIGS. Protrusions 24d and 25d projecting from the gaps 24b and 25b are provided, and the projections 24d and 25d abut against the inner edges of the gaps 24b and 25b, so that the pressing parts 24c and 25c are more than a certain distance. You may make it not bend. In short, a space is formed as a gap inside the cross section of the pressing roller, and a desired pressing force that can press the tube is secured by adjusting the radial direction X or the axial thickness Y of the pressing portion. In particular, the shape of the gap, the shape of the pressing portion, and the like are not limited to the illustrated form. Needless to say, even if the convex portion is provided so as to protrude from the inner edge of the gap toward the outer edge, the same effect can be obtained.

[Embodiments 6 and 7]
11 and 12, the pressing rollers 26 and 27 according to the sixth and seventh embodiments are obtained by inserting an elastic material such as a spring S or an elastomer E into the gap 21b of the pressing roller 21 according to the first embodiment. . In the pressing roller 26 according to the sixth embodiment shown in FIG. 11, a spring S, which is an elastic material, is inserted into a part of the gap 26b, and the pressing roller 27 according to the seventh embodiment shown in FIG. The elastomer E, which is an elastic material, is inserted into the entire portion 27b. In these embodiments, since the elastic material is inserted, the cost is slightly increased. However, it is possible to prevent the pressing portions 26c and 27c from being bent too much to secure a necessary pressing force, and the pressing rollers 26 and 27 can prevent the pressing force. Since the pressing force at the time of pressing the tube can be defined (set) more than the repulsive force of the inserted elastic body, there is an advantage that it is easy to ensure a desired pressing force that is the minimum necessary.

[Embodiment 8]
The pressing roller 28 according to the eighth embodiment shown in FIGS. 13 and 14 is formed by cutting off the outer peripheral surface of the pressing roller 21 according to the first embodiment or by partially forming a circular arc on the outer peripheral surface by a mold or the like at the time of molding. A deformed peripheral surface portion 28d having a reduced curvature is provided, and an outer roller 28e is loosely fitted on the outside of the pressing roller 28, and the tube (see reference numeral 102 in FIGS. 4 and 5) is pressed by the pressing roller 28 through the outer roller 28e. It is the structure to press. For this reason, even if the pressing portion 28c bends when the tube is pressed by the pressing roller 28, the outer peripheral surface which is the outer shape of the pressing roller 28 becomes substantially the same shape as the inner peripheral surface of the outer roller 28e as shown in FIG. Since the pressing portion 28c of the pressing roller 28 and the outer roller 28e integrally press the tube, the pressing portion 28c does not bend more than necessary.

  Thus, according to the tube pump having the pressing roller 28 and the outer roller 28e according to the eighth embodiment, the pressing portion 28c of the pressing roller 28 and the outer roller 28e integrally press the tube. Therefore, the necessary minimum pressing force can be ensured without bending too much. In addition, since the outer peripheral surface of the outer roller 28e does not slide with respect to the tube because it is pressed through the loosely fitted outer roller 28e, the tube pump can be pressed without being worn, and the durability of the tube pump is improved. improves.

[Embodiment 9]
The pressing roller 29 according to the ninth embodiment shown in FIG. 15 has a plurality of rotatable freely rotating on the outer peripheral surface together with the outer peripheral surface in the same manner as the pressing roller 106 of the tube pump 100 ′ according to the second conventional example. The rotating shaft 29a to which the pressing roller 29d is attached is a non-eccentric roller that coincides with the centroid of the axial section, and a gap portion 29b is formed inside the cross section of the pressing portion 29c to which the pressing roller 29d is attached. Yes. For this reason, according to the tube pump having the pressing roller 29 according to the ninth embodiment, the tube can be squeezed without being worn because the tube is pressed by the rotatable pressing roller 29d, and the tube is pressed. Since the pressing portion 29c can be bent by providing the gap portion 29b while ensuring the desired pressing force, there is an accuracy error in the installation interval between the rotating shaft 29a and the tube support surface 103 of the pump unit 101. Even if it is, a load more than necessary is not applied to the drive mechanism of the pressing roller 29.

  As described above, the image forming apparatus according to the embodiment of the present invention has been described by taking an inkjet color printer as an example. However, the image forming apparatus is not necessarily limited to such an image forming apparatus. The present invention can be applied to a general ink discharge type image forming apparatus such as a multi-function machine, which supplies or sucks ink from a main tank to a sub tank by a tube pump.

  The apparatus main body 1a, the cartridge loading unit 2, the operation display unit 3, the image forming unit 5, the paper feed unit 6, the paper transport unit 7, the paper discharge unit 8 and the like in the description of the image forming apparatus according to the embodiment are only described. An example is shown and the structure of another well-known apparatus, a means, etc. is employable. Even in such a case, it is clear that the same effect can be achieved with respect to the problem. Further, the shapes, structures, and the like of the respective constituent members shown in the drawings are merely preferable examples, and it goes without saying that the design can be appropriately changed within the scope of the claims.

1 Color printer (image forming device)
DESCRIPTION OF SYMBOLS 1a Apparatus main body 100,100 'Tube pump 102 Tube 103 Tube support surface 105,105' Pressure roller (conventional example 1,2)
21, 22, 23, 24, 25, 26, 27, 28, 29 Pressure roller (Examples 1 to 9)
21b, 22b, 23b, 24b, 25b, 26b, 27b, 28b, 29b Gap part 21c, 22c, 23c, 24c, 25c, 26c, 27c, 28c, 29c Pressing part 24d, 25d Protruding part 28d Deformation peripheral surface part 28e Outer roller 29d Pressing roller S Spring (elastic material)
E Elastomer (elastic material)

JP-A-2-238188 JP 2007-138793 A JP 2010-138742 A JP 11-192733 A JP 2007-138814 A

Claims (7)

An ink discharge type image forming apparatus that includes an elastic hollow tube serving as an ink flow path and a pressing roller that presses the tube by rotating the tube and supplies or sucks ink. In tube pump,
The tube pump according to claim 1, wherein the pressing roller has a hollow space formed inside a cross section of a pressing portion that contacts and presses the tube.   The tube pump according to claim 1, wherein the pressing roller is an eccentric roller having an eccentric rotation shaft.   The pressing roller has a convex portion protruding in the radial direction of the gap portion, and the convex portion is configured to abut against an edge of the gap portion so that the pressing portion does not bend more than a certain distance. The tube pump according to claim 1 or 2, characterized in that.   The tube pump according to any one of claims 1 to 3, wherein an elastic material is inserted into the gap.   5. The pressing roller, wherein the curvature of the outer peripheral surface is partially reduced, and an outer roller is loosely fitted to the outside of the pressing roller to press the tube through the outer roller. A tube pump according to any one of the above.   The pressing roller is a roller in which a rotating shaft having a plurality of pressing rollers attached to an outer peripheral surface is not eccentric, and a hollow space is formed inside a cross section of a portion to which the pressing rollers are attached. The tube pump according to claim 1, wherein: An ink cartridge that stores ink; a carriage that is movable in the main scanning direction; a recording head that is mounted on the carriage and that discharges ink onto paper; and the ink sent from the ink cartridge is temporarily stored to store the ink In an ink ejection type image forming apparatus, comprising: a head tank that sends to a recording head; and a pump that communicates with the ink cartridge and the head tank to supply ink to the head tank or suck ink from the head tank. ,
An ink discharge type image forming apparatus, wherein the tube pump according to any one of claims 1 to 6 is mounted as the pump.