JP5228885B2 - Tube pump and image forming apparatus - Google Patents

Description

  The present invention relates to a tube pump and an image forming apparatus.

  As an image forming apparatus such as a printer, a facsimile machine, a copying apparatus, a plotter, and a complex machine of these, for example, an ink jet recording apparatus is known as an image forming apparatus of a liquid discharge recording method using a recording head for discharging ink droplets. . This liquid discharge recording type image forming apparatus ejects ink droplets from a recording head onto a conveyed paper to form an image (recording, printing, printing, and printing are also used synonymously). Serial type image forming device that forms an image by ejecting droplets while the recording head moves in the main scanning direction, and a line type that forms images by ejecting droplets without the recording head moving There is a line type image forming apparatus using a head.

  In the present application, the “image forming apparatus” of the liquid discharge recording method is an apparatus that forms an image by landing ink on a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics or the like. In addition, “image formation” means not only giving an image having a meaning such as a character or a figure to a medium but also giving an image having no meaning such as a pattern to the medium (simply It also means that a droplet is landed on a medium). The “ink” is not limited to the ink, but is used as a general term for all liquids that can perform image formation, such as a recording liquid, a fixing processing liquid, and a liquid. The term “paper” is not limited to paper, but includes the above-described OHP sheet, cloth, and the like, and means that ink droplets adhere to the recording medium, recording medium, recording paper, recording It is used as a general term for what includes what is called paper.

  In such a liquid ejection type image forming apparatus, as an ink supply system for supplying ink to the recording head, ink is supplied from the replaceable main tank to the sub tank by the ink supply pump, and the sub tank to the recording head. Some supply ink. Further, in order to maintain and recover the reliability of the recording head, a maintenance recovery mechanism for capping the nozzle surface of the recording head with a cap member and sucking and discharging ink from the nozzle by a suction pump is provided.

  As such an ink supply pump or suction pump, a tube pump (tubing pump) is generally used. The tube pump includes, for example, a pump case (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 pump case, and a rotatable member that can rotate on 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 position that releases the pressing of the elastic tube. By rotating, the pressing part of the elastic tube by the pressing member moves to reduce the internal pressure on the upstream side to generate a negative pressure in the flow path of the elastic tube, and suck the liquid in the flow path of the elastic tube from one end side. And discharged to the other end side.

  However, since the tube pump performs suction or supply of liquid by crushing the elastic tube with a roller and pulling it out, a tube with appropriate elasticity (restoring force) must be used. There is a problem in that the gas barrier property is not sufficient, and the liquid inside evaporates to dry and thicken.

  Therefore, as described in Patent Document 1, the tube containing the tube pump and the container that holds the tube pressing means are hermetically sealed by bonding, rubber packing, or welding to prevent evaporation of liquid from the tube. It is known to plan.

JP 2006-305799 A

  However, the tube pump having the mechanism as described in Patent Document 1 has a problem that the assembly work and the number of parts increase because the pump is sealed. In addition, for example, in a liquid ejection type image forming apparatus, it is necessary to supply a plurality of types of different inks. In this case, a tube pump is provided for each color of ink. There is a problem that the installation space of the ink supply unit including the tube pump is increased.

  The present invention has been made in view of the above problems, and suppresses the evaporation of moisture from the tube while reducing the assembly of the tube pump and the increase in the number of parts, and reduces the installation space of a plurality of tube pumps. It aims to plan.

In order to solve the above-described problem, a tube pump according to claim 1 of the present invention provides:
At least two pump units comprising a tube through which a liquid passes, a pressing means that presses the tube while rotating, and a pump case in which one of the tube and the pressing means is housed in a recessed space, are integrated,
Each pump case of the two pump units wherein the concave space is fixed so as to face, the have a between the tubes and pushing means the concave space is tight closed space is accommodated,
A sealing member made of a member having a gas barrier property higher than that of the tube is interposed between the two pump cases .

  The image forming apparatus according to the present invention includes the tube pump according to the present invention.

According to the tube pump of the present invention, it is possible to suppress evaporation of water from the tube while reducing the increase in the assemblability and the number of components of the switch Yubuponpu, installation space is integrated a plurality of tube pump To reduce.

  According to the image forming apparatus of the present invention, since the tube pump according to the present invention is provided, stable ink supply can be performed by using the tube pump in the ink supply system, and stable by using the suction pump. Suction can be performed.

Embodiments of the present invention will be described below with reference to the accompanying drawings. First, an example of an image forming apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is an explanatory side view for explaining the overall configuration of the image forming apparatus, and FIG. 2 is an explanatory plan view of a main part of the apparatus.
This image forming apparatus is a serial type ink jet recording apparatus, and a carriage 33 is slidable in a main scanning direction by main and sub guide rods 31 and 32 which are guide members horizontally mounted on the left and right side plates 21A and 21B of the apparatus main body 1. It is held and moved and scanned in the direction indicated by the arrow (carriage main scanning direction) in FIG. 2 via a timing belt by a main scanning motor (not shown).

  The carriage 33 is provided with recording heads 34a and 34b composed of liquid ejection heads for ejecting ink droplets of yellow (Y), cyan (C), magenta (M), and black (K). The “recording head 34” is arranged in a sub-scanning direction orthogonal to the main scanning direction, and the ink droplet ejection direction is directed downward.

  Each of the recording heads 34 has two nozzle rows. One nozzle row of the recording head 34a has black (K) droplets, the other nozzle row has cyan (C) droplets, and the recording head 34b has one nozzle row. One nozzle row ejects magenta (M) droplets, and the other nozzle row ejects yellow (Y) droplets.

  The carriage 33 is equipped with sub tanks 35a and 35b (referred to as “sub tanks 35” when not distinguished) for supplying ink of each color corresponding to the nozzle rows of the recording head 34. The sub-tank 35 includes ink cartridges 10y, 10m, 10c, and 10k that are main tanks of the respective colors that are detachably attached to the cartridge loading unit 4, and are supplied by the supply pump unit 24 including the fluid supply device according to the present invention. Each color ink is replenished and supplied through the supply tube 36.

  On the other hand, as a paper feeding unit for feeding the papers 42 stacked on the paper stacking unit (pressure plate) 41 of the paper feeding tray 2, a half-moon roller (feeding) that separates and feeds the papers 42 one by one from the paper stacking unit 41. A separation pad 44 made of a material having a large friction coefficient is provided facing the paper roller 43) and the paper feed roller 43, and the separation pad 44 is urged toward the paper feed roller 43 side.

  In order to feed the paper 42 fed from the paper feeding unit to the lower side of the recording head 34, a guide member 45 for guiding the paper 42, a counter roller 46, a transport guide member 47, and a tip pressure roller. And a holding belt 48 which is a conveying means for electrostatically attracting the fed paper 42 and conveying it at a position facing the recording head 34.

  The transport belt 51 is an endless belt, and is configured to wrap around the transport roller 52 and the tension roller 53 and circulate in the belt transport direction (sub-scanning direction). Further, a charging roller 56 that is a charging unit for charging the surface of the transport belt 51 is provided. The charging roller 56 is disposed so as to come into contact with the surface layer of the transport belt 51 and to rotate following the rotation of the transport belt 51. The transport belt 51 rotates in the belt transport direction of FIG. 2 when the transport roller 52 is rotationally driven via a timing belt by a sub-scanning motor (not shown).

  Further, as a paper discharge unit for discharging the paper 42 recorded by the recording head 34, a separation claw 61 for separating the paper 42 from the conveying belt 51, a paper discharge roller 62, and a spur 63 that is a paper discharge roller. And a paper discharge tray 3 below the paper discharge roller 62.

  A duplex unit 71 is detachably mounted on the back surface of the apparatus body 1. The duplex unit 71 takes in the paper 42 returned by the reverse rotation of the conveyance belt 51, reverses it, and feeds it again between the counter roller 46 and the conveyance belt 51. The upper surface of the duplex unit 71 is a manual feed tray 72.

  Further, as shown in FIG. 2, a maintenance / recovery mechanism 81 for maintaining and recovering the state of the nozzles of the recording head 34 is disposed in the non-printing area on one side of the carriage 33 in the scanning direction. The maintenance / recovery mechanism 81 includes cap members (hereinafter referred to as “caps”) 82a and 82b (hereinafter referred to as “caps 82” when not distinguished from each other) for capping the nozzle surfaces of the recording head 34, and nozzle surfaces. A wiper member (wiper blade) 83 for wiping the recording medium, an empty discharge receiver 84 for receiving liquid droplets when performing empty discharge for discharging liquid droplets that do not contribute to recording in order to discharge the thickened recording liquid, and a carriage And a carriage lock 87 for locking 33. Further, a non-replaceable waste liquid tank 100 for accommodating waste liquid generated by the maintenance recovery operation can be replaced on the lower side of the maintenance recovery mechanism 81 of the head, and can be replaced on the side of the maintenance recovery mechanism 81 from the front side of the apparatus main body. Each of the liquid waste tanks 101 is provided.

  In addition, as shown in FIG. 2, in the non-printing area on the other side in the scanning direction of the carriage 33, idle discharge is performed to discharge liquid droplets that do not contribute to recording in order to discharge the recording liquid thickened during recording or the like. An empty discharge receiver 88 for receiving the liquid droplets at the time is disposed, and the empty discharge receiver 88 is provided with an opening 89 along the nozzle row direction of the recording head 34.

  In this image forming apparatus configured as described above, the sheets 42 are separated and fed one by one from the sheet feed tray 2, and the sheet 42 fed substantially vertically upward is guided by the guide 45, and includes the transport belt 51 and the counter. It is sandwiched between the rollers 46 and conveyed, and the leading end is guided by the conveying guide 37 and pressed against the conveying belt 51 by the leading end pressing roller 49, and the conveying direction is changed by approximately 90 °.

  At this time, a positive output and a negative output are alternately repeated with respect to the charging roller 56, that is, an alternating voltage is applied, and a charging voltage pattern in which the conveying belt 51 alternates, that is, in a sub-scanning direction that is a circumferential direction. , Plus and minus are alternately charged in a band shape with a predetermined width. When the paper 42 is fed onto the conveyance belt 51 charged alternately with plus and minus, the paper 42 is attracted to the conveyance belt 51, and the paper 42 is conveyed in the sub-scanning direction by the circular movement of the conveyance belt 51.

  Therefore, by driving the recording head 34 according to the image signal while moving the carriage 33, ink droplets are ejected onto the stopped paper 42 to record one line, and after the paper 42 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 42 has reached the recording area, the recording operation is finished and the paper 42 is discharged onto the paper discharge tray 3.

  When performing the maintenance and recovery of the nozzles of the recording head 34, the nozzle 33 performs the suction from the nozzles by moving the carriage 33 to a position facing the maintenance and recovery mechanism 81 which is the home position and performing capping by the cap member 82. By performing a maintenance and recovery operation such as idle ejection for ejecting droplets that do not contribute to image formation, image formation by stable droplet ejection can be performed.

Next, an example of an ink supply system in the image forming apparatus will be described with reference to a schematic explanatory diagram of FIG.
A sub tank 35 is integrally provided on the recording head 34 via a filter 300 and mounted on the carriage 33. The sub tank 35 is provided with a pair of (two) metal detection electrodes 302a and 302b for detecting the presence or absence of ink contained in the sub tank 35, and an air release means 304 for opening the inside to the atmosphere. It has been.

  One of the pair of detection electrodes 302a and 302b is connected to the positive side and the other is connected to the negative side. When the detection electrodes 302a and 302b are in contact with the ink 301, the electrical resistance between the two changes. Therefore, the presence or absence of ink can be detected. The air release means 304 accommodates a pressing pin 405 in which a packing portion having an elastic body is integrally formed by two-color molding, and is urged outward by a spring 306 installed in the sub tank 35. And the sub-tank 35 are cut off, and the pressing pin 405 is pressed against the biasing force of the spring 306 from the outside to open the atmosphere and the sub-tank 35. The sub tank 35 is provided with a pressure detection means (not shown) for detecting the pressure.

  The main tank 10 stores therein an ink bag 310 that can be deformed by an external pressure. The ink bag 310 is connected to a hollow supply needle (hollow needle) 223 provided in the tube pump 200 according to the present invention, which will be described later, when the main tank 10 is mounted on the apparatus main body.

  The tube pump 200 and the sub tank 35 constituting the supply pump unit 24 are connected by the supply tube 36, and the ink 301 is replenished and supplied from the main tank 10 to the sub tank 35 by driving the tube pump 200. The ink liquid level in the sub tank 35 when the initial ink filling into the sub tank 35 is completed is at a height h0 from the nozzle surface 34n of the recording head 34.

  Next, an embodiment of the tube pump according to the present invention, which is configured in the supply pump unit 24 in this image forming apparatus and supplies or sucks ink, will be described with reference to FIGS. 4 is a perspective explanatory view of the tube pump, FIG. 5 is a perspective explanatory view seen from the opposite side of FIG. 4, FIG. 6 is an exploded perspective explanatory view, and FIG. 7 is an exploded perspective explanatory view of the pump unit. FIG. 8 is an explanatory side view of the pump unit.

  In the tube pump 200, two pump units 201A and 201B (referred to as “pump unit 201” when not distinguished from each other) are fixed by sandwiching a seal member 230 between the pump cases 202 of the pump units 201A and 201B. It is integrated by doing.

  In the pump unit 201, a concave space 203 having an arcuate inner wall surface 203 a is formed in the pump case 202, and an elastic tube 204 through which ink passes and a pressing means 205 that presses the tube 204 while rotating. (Refer to FIG. 8), and a DC motor 207 which is a driving means for driving the pressing means 205 is housed in a recessed space 206 different from the recessed space 203.

  As shown in FIGS. 7 to 9, the pressing means 205 is attached with a ring 211, a pressing roller (collar) 212, a gear 213 with an eccentric cam, and a gear cover 214 around a shaft 210 attached to the pump case 203. Configured. The worm gear 215 attached to the motor 207 is engaged with the gear 213 with the eccentric cam.

  With reference to FIG. 9 as well, the pump unit 201 rotates the motor 207 forward or backward so that the gear 213 with the eccentric cam rotates via the worm gear 215 while the eccentric roller rotates, so that the pressing roller 212 is moved to the tube. The ink 204 is rotated while pressing the inner wall surface 203a of the recess space 203, and the tube 204 is pushed out while rotating in one of the arrow directions in FIG.

  Here, one end of the tube 204 is connected to the joint pipe 221 attached to the pump case 202, and the other end is connected to the joint pipe 222. A hollow needle 223 is provided in the joint pipe 221, and a supply tube 36 is connected to the joint pipe 222.

  The pressing means 205 of the pump unit 201 includes a plurality of (three in this example) rollers 712 provided on a rotating member 711 that is rotated by a shaft 710, for example, as shown in FIG. By doing so, it may be supplied (or sucked) by handling the tube 204 with the roller 712.

  Returning to FIG. 6, the tube pump 200 is a rubber having a higher gas barrier property than the tube 204 between the top surfaces of the pump cases 202 and 202 of the two pump units 201 </ b> A and 201 </ b> B described above. A seal member 230 made of a sheet, packing or the like is sandwiched between the tube 204 and the recessed spaces 203 and 203 containing the pressing means 205 so as to face each other using a claw 231, a locking piece (not shown) and a screw 233. The recessed spaces 203 and 203 of each pump case 202 are substantially sealed spaces.

  Here, as shown in FIG. 11, by providing protrusions (ribs) 241 having a triangular cross section over the entire circumference of one pump case 202 and biting into the seal member 230, the airtightness (sealing performance) is improved. Yes.

  The pump cases 202 and 202 of the two pump units 201A and 201B can be bonded and fixed by bonding, welding, or the like.

  In this way, the two pump units 201A and 201B are integrated to close the recessed space 203 that accommodates the tube 204 and the pressing means 205 in one place, so that it is excellent in assemblability and parts cost, and further, moisture is evaporated. The number of locations is smaller than when each pump unit 201 is sealed separately, and further gas barrier properties can be improved.

  That is, since the tube pump 200 supplies or sucks ink using the restoring force when the tube 204 is crushed and returned to the original state, the tube 204 has an appropriate elasticity that does not increase the rotational torque of the pump driving force excessively. It is made of elastic material with force. For example, tubes having a hardness of about 50 to 65 are preferably used, but these tubes have low gas barrier properties, and moisture evaporates to increase the viscosity of the ink inside. On the other hand, since an ink jet recording apparatus uses a plurality of colors of ink, it is necessary to provide a tube pump for each color.

  In this case, if the two tube pumps are separately provided to have a sealed structure, the assemblability is poor and the number of parts increases. On the other hand, according to the tube pump according to the present invention, at least two pump units are integrated and the pump case is fixed in a substantially hermetically sealed structure, so that the assembling property can be improved and the number of parts can be reduced. Space saving can be achieved when installing a plurality of tube pumps.

  Further, in the pump unit 200, as shown in FIGS. 8 and 12, the space between the partition wall 208 between the recessed space 206 that houses the motor 207 and the recessed space 203 that houses the tube 204 and the like is between the motor 207. In addition, a seal member 250 made of a rubber sheet, packing or the like having a higher gas barrier property than the tube 204 is provided around the motor shaft 207a of the motor 207. The motor shaft around the motor 207 may be sealed with an adhesive. As shown in FIG. 13, an elastic member 253 that presses the motor 207 toward the seal member 250 is provided between the motor 207 and the pump case 202.

  As a result, the recess space 203 that accommodates the tube 204 or the like is cut off between the seal member 251 and the recess space 206 that accommodates the motor 207 by the motor 207, so that the recess space 203 does not have to be sealed. Is sealed. Then, the recess space 203 and the recess space 206 are blocked, so that a slit 252 can be formed in the recess space 206 as shown in FIG. 4 and the heat generated by the motor 207 can be released to the outside. In this case, since the recessed space 203 and the recessed space 206 are blocked, heat generated by the motor 250 is also prevented from entering the recessed space 203 side.

Next, a connection portion between the tube 204 and the joint portions 221 and 222 will be described with reference to FIGS.
First, as shown in FIG. 14, a line 280 is provided on the surface of the tube 204, a joint pipe mark 281 of the joint 221 is provided, and a joint mark 282 is provided on the joint 222. Therefore, the tube can be prevented from being twisted at the time of assembly, and a load caused by twisting at the time of liquid feeding, and a decrease in liquid feeding (function deterioration) can be prevented.

  As shown in FIGS. 15 and 16, the base of the tube mounting portion 222 a of the joint 222 is undercut. Then, after inserting the retaining ring 284 into the tube 204 in advance and inserting the tube 204 into the tube mounting portion 222a of the joint 222, as shown in FIG. 17, hold the retaining ring 284 in the direction of the arrow until it reaches the undercut portion of the joint 222. To go. Since the retaining ring 284 has a spring shape, it can be opened by turning in the direction of the arrow, and can easily get over a portion with a large outer diameter before the undercut. As a result, the snap ring 284 can be attached by rotating it once or twice, and workability can be improved. The tube 204 can be attached to the joint 221 in the same manner.

  The function of the retaining ring 284 is to prevent ink from leaking into the machine (inside the device) by preventing the joint and tube from coming off due to an increase in the internal pressure when ink is constantly fed during abnormal operation of the drive motor. be able to.

Next, the ink thickening prevention structure in the tube pump 200 will be described with reference to FIG.
In the same figure, for example, grease is filled so that the space indicated by the broken line 285 disappears, so that the ink moisture in the tube 204 can be removed from the tube 204 when stored for a long period of time or when not used for a long period of time. Due to the temperament, it is possible to shorten the saturation time when evaporating in the pump case 202, and it is possible to more reliably reduce ink thickening.

  In the above embodiment, the tube pump according to the present invention is used as an ink supply pump. However, the tube pump may be used as a suction pump that performs suction from the cap 82a of the maintenance / recovery mechanism 81. Further, it can be used not only for image forming apparatuses but also for general tube pump applications.

  The image forming apparatus according to the present invention can be applied to a facsimile apparatus, a copying apparatus, a printer / fax / copier multifunction machine, etc., in addition to an ink jet printer. Furthermore, the present invention can also be applied to an image forming apparatus that discharges a liquid (recording liquid) other than ink, such as a resist or a DNA sample in the medical field.

1 is a configuration diagram showing an outline of a mechanism part of an image forming apparatus according to the present invention. It is principal part plane explanatory drawing of the mechanism part. FIG. 2 is a schematic explanatory diagram illustrating an example of an ink supply system in the image forming apparatus. It is a perspective explanatory view showing an example of a tube pump concerning the present invention. FIG. 5 is a perspective view similarly viewed from the opposite side of FIG. 4. It is an exploded perspective view similarly. It is an exploded perspective view of the pump unit. It is side surface explanatory drawing of the pump unit. It is a principal part schematic explanatory drawing used for description of the press means of the pump unit. It is principal part typical explanatory drawing which shows the other example of the press means of the pump unit. It is principal part cross-sectional explanatory drawing used for description of the clamping structure of a pump case and a sealing member. It is principal part explanatory drawing used for description of the motor accommodating part of the pump unit. It is a principal part explanatory drawing similarly provided for description of a motor accommodating part. It is side surface explanatory drawing used for description of the connection of the joint of the pump unit, and a tube. It is perspective explanatory drawing with which the description of the attachment structure of the joint and a tube is provided. It is a perspective explanatory view similarly provided for description before tube attachment. It is a perspective explanatory view of a retaining ring. It is side surface explanatory drawing used for description of the ink thickening prevention structure of the pump unit.

Explanation of symbols

10 ... Ink cartridge (main tank)
33 ... Carriage 34, 34a, 34b ... Recording head (liquid ejection head)
35 ... Sub tank 36 ... Supply tube 200 ... Tube pump 201, 201A, 201B ... Pump unit 202 ... Pump case 203 ... Recessed space 204 ... Tube 205 ... Pressing means 206 ... Recessed space 207 ... Motor 230 ... Sealing member

Claims (4)

At least two pump units comprising a tube through which a liquid passes, a pressing means that presses the tube while rotating, and a pump case in which one of the tube and the pressing means is housed in a recessed space, are integrated,
Each pump case of the two pump units wherein the concave space is fixed so as to face, the have a between the tubes and pushing means the concave space is tight closed space is accommodated,
A tube pump, wherein a seal member made of a member having a higher gas barrier property than the tube is interposed between the two pump cases . The tube pump according to claim 1 , wherein at least one of the two pump cases is provided with a protrusion that presses the seal member. At least two pump units comprising a tube through which a liquid passes, a pressing means that presses the tube while rotating, and a pump case in which one of the tube and the pressing means is housed in a recessed space, are integrated,
Each of the pump cases of the two pump units is fixed with the recessed space facing each other, and the recessed space in which the tube and the pressing means are accommodated is a sealed space,
In the pump case, a driving means for driving the pressing means is accommodated in a recessed space different from the recessed space,
A tube pump characterized in that a seal member made of a member having a gas barrier property higher than that of the tube is interposed between the recessed space containing the driving means and the recessed space containing the pressing means. . An image forming apparatus characterized by comprising a tube pump according to any one of claims 1 to 3.

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