JP5272524B2 - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that the draining of ink of increased viscosity and bubbles are low, and an ink exhausting amount is large, and then a pressure fluctuation following a pulsing during the suction occurs, by generating a negative pressure by performing the suction with a tube pump by sealing the nozzle face of recording head with a cap and then to performing the suction from the nozzle. <P>SOLUTION: An image formation device includes a cap 62 for capping the nozzle face 204 of a head 101 for discharging liquid droplets, a negative pressure generating chamber 67 connected to the cap 62 through a suction course 65, a pressure opening/closing valve 66 for opening and closing the course 65 between the cap 62 and the negative pressure generating chamber 67, a suction pump 63 for negative pressure generation for changing the inside of the negative pressure generating chamber 67 into a negative pressure state, and a control means which operates the suction pump 63 in the state that the pressure opening/closing valve 66 is closed and controls the operation of opening the pressure opening/closing valve 66 is changing the inside of the negative pressure generating chamber 67 into the negative pressure state. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus provided with a recording head for discharging droplets.

  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 means that ink droplets are transported from a recording head (not limited to paper, including OHP, and can be attached to ink droplets and other liquids). Yes, it is also ejected onto a recording medium or a recording medium, recording paper, recording paper, etc.) to form an image (recording, printing, printing, and printing are also used synonymously). And a serial type image forming apparatus that forms an image by ejecting liquid droplets while the recording head moves in the main scanning direction, and a line type head that forms images by ejecting liquid droplets without moving the recording head There are line type image forming apparatuses using

  In the present application, the “image forming apparatus” of the liquid ejection method is an apparatus that forms an image by ejecting liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, or the like. In addition, “image formation” means not only that an image having a meaning such as a character or a figure is imparted to the medium but also an image having no meaning such as a pattern is imparted to the medium (simply liquid. It also means that a droplet hits the medium). “Ink” is not limited to ink, but is used as a general term for all liquids capable of image formation, such as recording liquid, fixing processing liquid, and liquid. DNA samples, resists, pattern materials and the like are also included.

  In such an image forming apparatus (hereinafter, also simply referred to as “inkjet recording apparatus”), the recording head is caused by the evaporation of the solvent from the nozzle because of recording by discharging ink from the nozzle onto the paper. Maintenance and recovery to maintain and recover the performance of the print head due to problems such as increased ink viscosity, ink solidification, dust adhesion, and bubble failure due to air bubbles. It has a mechanism.

  For example, a cap (also referred to as a capping unit or a cap member) that seals the nozzles of the recording head is provided, and capping of the recording head is performed when the apparatus is not in operation, thereby suppressing drying and thickening of ink in the nozzles. To be able to. In addition, before and after the recording operation and during the recording operation, ink droplets that do not contribute to the recording operation are discharged, and the ink dried and thickened in the nozzles is discharged so that the discharge performance can be recovered and maintained. .

  The ejection of ink droplets that do not contribute to image formation for maintaining the ejection performance of the nozzles is called preliminary ejection or idle ejection, and can be ejected to a dedicated idle ejection receiver or ejected to a cap. Is called.

A conventional maintenance / recovery mechanism generally includes a suction pump including a tube connected to a cap and a tube pump for generating suction force on the tube.
JP 2008-023781 A

In Patent Document 2, a valve unit that opens and closes an ink supply path is disposed in an ink supply path that supplies ink from an ink storage unit to a recording head, and the suction pump is driven and capped with the valve unit closed. There is described what controls the valve unit to open in a state where negative pressure is accumulated in the internal space of the means.
Japanese Patent No. 3978956

  However, since the above-described tube pump is configured to generate suction force by utilizing deformation of the tube, the pressure change in the suction cap gradually increases from the start of driving of the suction pump, so that the air bubbles inside the recording head can be discharged. In order to perform suction at a high negative pressure that is effective for this, it takes time until the pressure rises, and there is a problem that the amount of ink discharged (ink amount to be discarded) increases because it takes time.

  In addition, there is a pulsation peculiar to the tube pump at the time of suction, and a stable pressure cannot be continuously applied, and there is also a problem that the discharge property of the thickened ink and bubbles is lowered.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems. In the maintenance and recovery operation of the recording head, the thickened ink and the bubble discharge performance are improved, the ink discharge amount is reduced, and there is no pressure fluctuation due to pulsation during suction. The purpose is to enable suction.

In order to solve the above problems, an image forming apparatus according to the present invention provides:
A recording head for discharging droplets;
A cap member for capping the nozzle surface of the recording head;
A negative pressure generating chamber connected to the cap member via a suction path;
Opening and closing means for opening and closing a path between the cap member and the negative pressure generating chamber;
A negative pressure generating pump for bringing the negative pressure generating chamber into a negative pressure state;
With the operation of the previous SL negative pressure generating pump and a control unit that Gyosu control the opening and closing of said switching means,
The control means closes the opening and closing means, operates the negative pressure generating pump to bring the negative pressure generating chamber into a negative pressure state, and continues the operation of the negative pressure generating pump, The configuration is such that the opening / closing means is controlled to open and close multiple times .

According to the onset bright, it is possible to start the suction to increase in a short period of time a negative pressure in the caps member improves the viscosity-increased ink and the bubble discharge resistance, also reduces further the ink discharge amount, further during aspiration Suction without pressure fluctuations due to the pulsation.

  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. 1 is a schematic configuration diagram for explaining the overall configuration of the image forming apparatus, and FIG. 2 is a schematic plan explanatory diagram of the apparatus.

  This image forming apparatus is a line type image forming apparatus, and includes an apparatus main body 1, a paper feed tray 2 on which paper P is stacked and fed, a paper discharge tray 3 on which printed paper P is discharged and stacked, and paper P An image forming unit 5 including a transport unit 4 that transports the paper from the paper feed tray 2 to the paper discharge tray 3, a head module 51 that discharges and prints droplets on the paper P transported by the transport unit 4, and Ink is supplied to the cleaning device 6 that is a maintenance and recovery mechanism that performs maintenance and recovery of each recording head of the image forming unit 5 at a required timing, the conveyance guide portion 7 that opens and closes the cleaning device 6, and the head module 51 of the image forming unit 5. An ink tank unit 8 for supplying ink and a main tank unit 9 for supplying ink to the ink tank unit 8 are provided.

  The apparatus main body 1 includes front and rear side plates and stays (not shown), and the sheets P stacked on the sheet feed tray 2 are fed one by one to the transport unit 4 by the separation roller 21 and the sheet feed roller 22. Is done.

  The transport unit 4 includes a transport drive roller 41a, a transport driven roller 41b, and an endless transport belt 43 wound around these rollers 41a and 41b. A plurality of holes (not shown) are formed on the surface of the transport belt 43, and a suction fan 44 that sucks the paper P is disposed below the transport belt 43. Further, conveyance guide rollers 42a and 42b are respectively held on guides (not shown) on the conveyance driving roller 41a and conveyance driven roller 41b and are in contact with the belt 43 by their own weight.

  The conveyance belt 43 rotates around when the conveyance driving roller 41 a is rotated by a motor (not shown), and the paper P is sucked onto the conveyance belt 43 by the suction fan 44 and is conveyed by the rotation movement of the conveyance belt 43. The transport driven roller 41 b and the transport guide rollers 42 a and 42 b rotate following the transport belt 43.

  An image forming unit 5 composed of a plurality of head modules 51 for discharging droplets to be printed on the paper P is disposed above the transport unit 4 so as to be movable in the arrow A direction (and the reverse direction). The image forming unit 5 is moved to above the cleaning device 6 during the maintenance and recovery operation (during cleaning), and is returned to the position shown in FIG. 1 during image formation.

  In the image forming unit 5, head modules 51a, 51b, 51c, 51d in which a plurality of heads having two nozzle rows in which a plurality of nozzles for discharging liquid droplets are arranged in a row are arranged in a line along the paper transport direction. Attached to the base member 52 is arranged. Here, one of the two nozzle rows of the head modules 51a and 51b ejects yellow (Y) droplets and the other of the magenta (M) droplets, and the two nozzle rows of the head modules 51c and 51d. On the other hand, cyan (C) droplets are discharged, and on the other hand, black (K) droplets are discharged.

  That is, in the image forming unit 5, two head modules 51 that discharge droplets of the same color are arranged side by side in the paper transport direction, and the two head modules 51 form a nozzle row corresponding to the paper width. It has a configuration.

  On the upstream side of the image forming unit 5, an ink tank 81 of the ink tank unit 8 (only one ink tank is provided with a reference for convenience of illustration) is arranged, and each head module unit is connected via a supply tube 82. 51, and a negative pressure for each head of the head module 51 is formed by a water head difference between the ink tank 81 and the head module 51. The ink tank unit 8 is arranged so as to be movable in the direction of arrow A together with the image forming unit 5. The supply tube 82 from the ink tank 81 to the head module 51 is shown connected from above the head module 51 for easy understanding. However, as will be described later, the longitudinal direction of the head module 51 (paper conveyance direction) To the end of the direction orthogonal to the direction.

  Further, the main tank unit 9 is disposed on the upstream side of the ink tank 81, and ink is supplied from the main tank 91 through the supply tube 92 to the ink tank 81.

  On the downstream side of the transport unit 4, a transport guide portion 7 that discharges the paper P to the paper discharge tray 3 is provided. The paper P guided and conveyed by the conveyance guide unit 7 is discharged to the paper discharge tray 3. The paper discharge tray 3 includes a pair of side fences 31 that regulate the width direction of the paper P and an end fence 32 that regulates the front end of the paper P.

  The maintenance / recovery mechanism (cleaning device) 6 includes four rows of cleaning means 61 a to 61 d corresponding to each head module 51 of the image forming unit 5, and one cleaning means 61 is provided for each head of the head module 51. The corresponding cap member 62 and a wiper member (not shown) are configured. The cap member 62 of each cleaning means 61 can be moved up and down independently for each row. Further, below the cleaning unit 61, suction pumps 63a to 63d for sucking ink from the nozzles with the cap member 62 capping the nozzle surface of the head module 51 are arranged.

  Further, in this image forming apparatus, after the printing is finished, when the nozzle surface of each head of the head module 51 that discharges droplets is capped by the cleaning unit 61, or ink is sucked from the nozzle, or the head module 51 When the ink adhering to the nozzle surface of each head is cleaned with a wiping member, as shown in FIG. 1, after the printing is stopped, the entire transport unit 4 rotates in the arrow B direction with the transport driven roller 41b as a fulcrum, A space for moving the image forming unit 5 is ensured by making the space between the image forming unit 5 larger than that at the time of image formation. At this time, the conveyance guide portion 7 disposed on the upper portion of the cleaning device 6 is also rotated upward in the direction of the arrow C at the fulcrum 71, and the upper portion of the cleaning device 6 is opened.

  Then, after the transport unit 4 and the transport guide portion 7 are released (released), the image forming unit 5 moves in the paper passing direction (in the direction of arrow A), stops above the cleaning device 6, and the cleaning unit 61. Rises and shifts to a cleaning operation (maintenance recovery operation) of each head module 51.

  Next, details of the head module will be described with reference to FIGS. 3 is a perspective view of the head module, FIG. 4 is a front view of the head module excluding the leaf spring member and the base member, FIG. 5 is a schematic side view of the head module, and FIG. It is bottom surface explanatory drawing of one head of the head module.

  One head module 51 arranges a plurality of heads 101 (in this example, five examples) for ejecting droplets in a row on a base member 102 and arranges the heads on the plurality of heads 101. A branch member (common channel member) 104 that is a liquid supply member that forms a common channel 105 that distributes and supplies ink to a plurality of heads 101 along the direction is disposed. The head 101 is urged toward the branching member 104 by the leaf spring member 103 sandwiched between them to be integrated.

  For example, as shown in FIG. 9, the head 101 has a nozzle surface 204 having nozzle rows 201A and 201B in which a plurality of nozzles 201 for discharging droplets are arranged. The head 101 is not limited to this, and a head having three or more nozzle rows can also be used.

  The branching member 104 has a common liquid chamber 105 inside, and supplies two common liquids at a partition wall (not shown) along the longitudinal direction of the branching member in order to supply different colors to the nozzle rows 201A and 201B of each head 101. In order to supply different colors of ink to the two common liquid chambers 105, ink supply ports 106a and 106b to which ink from the sub tank 81 is supplied are provided at the ends in the head arrangement direction. The top surface 105a of the common liquid chamber 105 is formed obliquely, and air vents (atmospheric communication paths) 107a and 107b are formed at the highest portion of the top surface 105a.

  Further, the branch member 104 includes a main body 104a having a concave portion that becomes the common flow path 105, and side wall members 104b and 104b that close the opening of the main body 104a from both sides.

  The leaf spring member 103 has a bridging portion 103a that abuts against the outer top surface of the branching member 104, and a locking portion 103b that locks the base member 102, and the head 101 is moved through the base member 102 by elastic restoring force. It is urged and held in the direction of pressing toward the branch member 104 (the direction indicated by the arrow in FIG. 5). The leaf spring member 103 is engaged with an engagement pin 104 c provided on the upper surface of the branch member 104, and two leaf spring members 103 are provided for one head 101.

Next, a first embodiment of the present invention applied to this image forming apparatus will be described with reference to FIG. FIG. 7 is a schematic explanatory diagram for explaining the embodiment.
The ink 300 is supplied from the ink tank 81 to the head 101 as a recording head via the ink supply path 82 (and the branching member 104 not shown here), and a difference in water head between the ink tank 81 and the head 101 leads to the head 101. Negative pressure is formed. The ink tank 81 is provided with an air release passage 84 for opening the inside to the atmosphere, and an air release valve 85 for opening and closing the air release passage 84.

  Then, a cap 62 for capping the nozzle surface 204 of the head 101, a suction tube 65 that also serves as a discharge path and a suction path for discharging the waste liquid of ink in the cap 62, and pressure opening / closing as opening / closing means for opening / closing the suction tube 65 A suction pump 63 as a negative pressure generating pump composed of a valve 66, a negative pressure generating chamber 67 provided on the downstream side of the pressure opening / closing valve 66, and a tube pump provided on the downstream side of the negative pressure generating chamber 67. The waste liquid 301 discharged from the other end of the suction tube 65 is discharged to the waste liquid tank 69.

The part related to the control in this embodiment will be described with reference to the block diagram of FIG.
The control unit includes a main control unit 501 configured by a microcomputer that also serves as a control unit according to the present invention that controls the entire image forming apparatus. The main control unit 501 sends print data to the head control circuit 502 in order to form an image on a sheet based on image data transferred from an external information processing apparatus or the like and various command information.

  The head control circuit 502 generates data for driving the pressure generating means for ejecting the droplets of the head 101 based on the print data signal received from the main control unit 501, and transfers and transfers this data. The various signals necessary for determining the signal are transferred to the head driver included in the head module 51, and the storage unit as drive waveform data storage means, the D / A converter for converting the drive waveform data, and the voltage A drive waveform generation unit composed of an amplifier, a current amplifier, etc., and a selection means for selecting a drive waveform to be given to the head driver, a drive composed of one drive pulse (drive signal) or a plurality of drive pulses (drive signal) A waveform is generated and output to the head driver to drive and control the head 101.

  Further, the main control unit 501 drives and controls a motor 504 that moves the cleaning unit 61 including the cap 62 up and down, a motor 505 that drives the suction pump 63, and a solenoid 506 that opens and closes the on-off valve 66 via the driver 503. The main control unit 501 also performs control related to paper feeding and conveyance, movement of the image forming unit 5, and the like, but is not shown.

Next, the maintenance recovery control in this embodiment will be described with reference to the flowchart of FIG.
When performing a maintenance recovery operation including head suction for sucking and discharging ink from the nozzles 201 of the head 101 into the cap 62, the cap 62 is raised to cap the nozzle surface of the head 101, the pressure on-off valve 66 is closed, and suction is performed. The pump 63 is activated. As a result, the inside of the negative pressure generating chamber 67 is in a negative pressure state. Therefore, after the suction pump 63 is driven for a predetermined time (predetermined amount) to bring the negative pressure generating chamber 67 into a required negative pressure state, the atmosphere in the ink tank 81 is The release valve 85 is opened to make the pressure on the head 101 side positive, the pressure on / off valve 66 is opened, and the path between the cap 62 and the negative pressure generating chamber 67 is opened.

  Then, the sealed space formed between the nozzle surface 204 of the head 101 and the cap 62 becomes a high negative pressure state in a short time due to the negative pressure in the negative pressure generating chamber 67, and ink is discharged from the nozzle 102 of the head 101 to the cap 62. It is sucked and discharged inside.

  In this way, the discharge path 65 of the cap 62 is closed by the pressure opening / closing valve 66, the negative pressure generating chamber 67 is brought into a negative pressure state by the suction pump 63, and then the pressure opening / closing valve 66 is opened, thereby The inside of the cap 62 capping the surface 204 becomes a large negative pressure in a short time.

  That is, as shown in FIG. 10, when the suction pump (tube pump) 63 is connected to the cap 62 as it is through the tube 65 and the suction pump 63 is driven to make the inside of the cap 62 have a negative pressure, the suction pump 63 The negative pressure rises slowly and pulsation occurs. On the other hand, when the inside of the cap 62 is made negative by opening the pressure on / off valve 66 after the negative pressure generating chamber 67 is brought into a negative pressure state by the suction pump 63, the negative pressure in the cap 62 can be increased at once. it can.

  As a result, since ink is sucked from the nozzle 201 of the head 101 with a large negative pressure, the discharge property of thickened ink and bubbles is improved, and suction can be performed in a short time and the ink discharge amount is reduced. . Further, even if a tube pump is used as the suction pump, pressure fluctuation due to pulsation during suction can be prevented, and suction without pressure fluctuation can be performed.

Next, a second embodiment of the present invention will be described with reference to FIGS. 11 is a schematic explanatory diagram for explaining the embodiment, and FIG. 12 is a schematic explanatory diagram for explaining the operation.
Here, a negative pressure generation chamber 167 connected to a cap 62 (not shown) via a suction path 165, and a pressure on-off valve as an opening / closing means disposed between the cap 62 and the negative pressure generation chamber 167 to open and close the suction path 165 166, a discharge path 168 connected to the negative pressure generation chamber 167, and a vacuum pump 163 that sucks air in the negative pressure generation chamber 167 through the discharge path 168 to bring the negative pressure generation chamber 167 into a negative pressure state. It has. The negative pressure generating chamber 167 is formed by forming a sealed space 167c with the container main body 167a and the lid member 167b.

  Since it comprised in this way, as shown in FIG. 11, by discharging the air 171 in the container of the pressure generation chamber 167 with the vacuum pump 163 in the state which closed the pressure on-off valve 166, as shown in FIG. The inside of the container of the pressure generation chamber 167 becomes a decompressed air 172 and is in a negative pressure state. The negative pressure at this time is preferably increased from about -70 kPa to -100 kPa.

  Thereafter, the pressure on-off valve 167 is opened, whereby the inside of the cap 62 is sucked and ink is sucked and discharged from the nozzle. At this time, the waste liquid of ink sucked and accumulated in the pressure generation chamber 167 through the suction path 165 is discharged from a drain path (not shown).

Next, a third embodiment of the present invention will be described with reference to FIGS. FIG. 13 is a schematic explanatory view for explaining the embodiment, and FIGS. 14 and 15 are schematic explanatory views for explaining the operation.
In this embodiment, the negative pressure generating chamber is an elastic tube. In other words, the pressure on / off valve 266 that is the opening / closing means is disposed upstream of the elastically deformable tube (elastic tube) 260 connected to the cap 62 (not shown), and the suction pump 263 is separated from the pressure on / off valve 266 by a required distance. The elastic tube 260 on the upstream side of the pressure on-off valve 266 is a suction path 265, and the elastic tube 260 between the pressure on-off valve 266 and the suction pump 263 is a negative pressure generating chamber 267. The elastic tube 260 forms a discharge path 268 on the downstream side of the suction pump 263.

  With this configuration, by operating the suction pump 263 with the pressure on-off valve 266 closed as shown in FIG. 13, the ink remaining in the negative pressure generating chamber 267 as shown in FIG. The waste liquid 301 is discharged, the elastic tube 260 is deformed, and the portion 167a of the negative pressure generating chamber 267 of the elastic tube 260 rises to a high negative pressure. The negative pressure at this time is preferably increased from about -70 kPa to -100 kPa.

  Therefore, as shown in FIG. 15, when the pressure on / off valve 266 is opened from this state, the portion of the negative pressure generating chamber 267 of the elastic tube 260 is restored to its original shape by the elastic restoring force, and the inside of the cap 62 is restored by this restoration. The ink waste liquid 302 corresponding to the volume change of the elastic tube 267 is sucked by the negative pressure.

Next, a fourth embodiment of the present invention will be described with reference to FIGS. FIG. 16 is a schematic explanatory view for explaining the embodiment, and FIG. 17 is a schematic explanatory view for explaining the operation.
This embodiment is an example in which the negative pressure generating chamber is configured by a metal or resin bellows tube (bellows-like member). That is, a pressure on / off valve 366 as an opening / closing means is provided on the upstream side of a bellows pipe 360 connected to a cap 62 (not shown), and a bellows portion on the downstream side of the pressure on / off valve 366 serves as a negative pressure generating chamber 367 to generate negative pressure. A suction pump 363 is disposed downstream of the chamber 367, and a discharge path 368 is formed downstream of the suction pump 363.

  With this configuration, by operating the suction pump 363 with the pressure on / off valve 366 closed as shown in FIG. 16, the bellows that becomes the negative pressure generating chamber 367 of the bellows pipe 360 as shown in FIG. The waste liquid 301 of ink remaining in the portion is discharged, the bellows portion that becomes the negative pressure generating chamber 367 contracts, and the negative pressure generating chamber 367 rises to a high negative pressure. The negative pressure at this time is preferably increased from about -70 kPa to -100 kPa.

  Therefore, when the pressure on-off valve 366 is opened from this state, the bellows portion that becomes the negative pressure generating chamber 367 of the bellows pipe 369 is restored to the original shape shown in FIG. Becomes a negative pressure, and the ink corresponding to the volume change of the bellows tube 360 is sucked.

Next, different examples of the driving (operation) of the negative pressure generating pump and the opening / closing operation of the pressure on / off valve in the above embodiments will be described with reference to FIGS. 18 and 19. Here, the example of the first embodiment will be described.
In the example shown in FIG. 18, as described above, with the pressure on / off valve 66 closed (OFF state), the negative pressure generating pump 63 is turned on for a predetermined time to bring the negative pressure generating chamber 67 into a negative pressure state. . Thereafter, by opening the pressure on-off valve 66 (turning it on), the negative pressure in the cap 62 rises sharply, for example, from −0 kPa to −90 kPa. As a result, ink is sucked and discharged into the cap 62.

  On the other hand, in the example shown in FIG. 19, with the pressure on-off valve 66 closed (OFF state), the negative pressure generating pump 63 is turned on to bring the negative pressure generating chamber 67 into a negative pressure state. The negative pressure in the cap 62 rises sharply from, for example, −0 kPa to −90 kPa by opening and closing the pressure on / off valve 66 a plurality of times after a predetermined time has elapsed while continuing to drive the negative pressure generating pump 63. The descending change is intermittently performed a plurality of times. Thus, the bubble discharge | emission property in the head further can be improved by raise | generating a sudden pressure change continuously.

  In the above-described embodiment, an example in which the present invention is applied to a line type image forming apparatus has been described. However, the present invention can be similarly applied to a serial type image forming apparatus.

1 is a schematic side view illustrating an overall configuration of an example of an image forming apparatus according to the present invention. Similarly it is principal part plane explanatory drawing. It is a perspective explanatory view of a head module. It is front explanatory drawing except the leaf | plate spring member and base member of the head module. It is a side surface schematic explanatory drawing of the head module. It is bottom surface explanatory drawing of one head of the head module. It is typical explanatory drawing with which it uses for description of 1st Embodiment of this invention. It is a block explanatory view showing an outline of a control unit of the embodiment. It is a flowchart with which it uses for description of maintenance recovery control similarly. It is explanatory drawing explaining the change with respect to time of the negative pressure value in a cap at the time of using the case where the negative pressure generation chamber which concerns on this invention is used, and a tube pump. It is typical explanatory drawing with which it uses for description of 2nd Embodiment of this invention. It is a typical explanatory view similarly used for operation explanation. It is typical explanatory drawing with which it uses for description of 3rd Embodiment of this invention. It is a typical explanatory view similarly used for operation explanation. It is a typical explanatory view similarly used for operation explanation. It is typical explanatory drawing with which it uses for description of 4th Embodiment of this invention. It is a typical explanatory view similarly used for operation explanation. It is explanatory drawing with which it uses for description of an example of the drive (operation | movement) of the negative pressure generation pump in each embodiment, and the opening / closing operation | movement of a pressure on-off valve. It is explanatory drawing with which it uses for description of the drive (operation | movement) of the negative pressure generation | occurrence | production pump in each embodiment, and other examples of the opening / closing operation | movement of a pressure on-off valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Apparatus main body 4 ... Conveyance unit (conveyance part)
5. Image forming unit 6. Cleaning device (maintenance and recovery mechanism)
DESCRIPTION OF SYMBOLS 7 ... Conveyance guide part 8 ... Ink tank unit 9 ... Main tank unit 51 ... Head module 52 ... Line head base member 61 ... Cleaning means 62 ... Cap 63 ... Suction pump 65 ... Suction path 66 ... Pressure on-off valve 67 ... Negative pressure generation Chamber 101 ... Head 104 ... Branching member 163 ... Vacuum pump 165 ... Suction path 166 ... Pressure switching valve 167 ... Negative pressure generating chamber 260 ... Elastic tube 263 ... Suction pump 265 ... Suction path 266 ... Pressure switching valve 267 ... Negative pressure generating chamber 360 ... Bellows pipe 363 ... Vacuum pump 365 ... Suction path 366 ... Pressure on-off valve 367 ... Negative pressure generating chamber

Claims (6)

A recording head for discharging droplets;
A cap member for capping the nozzle surface of the recording head;
A negative pressure generating chamber connected to the cap member via a suction path;
Opening and closing means for opening and closing a path between the cap member and the negative pressure generating chamber;
A negative pressure generating pump for bringing the negative pressure generating chamber into a negative pressure state;
With the operation of the previous SL negative pressure generating pump and a control unit that Gyosu control the opening and closing of said switching means,
The control means closes the opening and closing means, operates the negative pressure generating pump to bring the negative pressure generating chamber into a negative pressure state, and continues the operation of the negative pressure generating pump, An image forming apparatus, wherein the opening / closing means is controlled to open and close a plurality of times .   The image forming apparatus according to claim 1, further comprising an ink tank that supplies ink to the recording head, the ink tank including an air release unit that opens to the atmosphere, and the negative pressure generating chamber is in a negative pressure state. The ink tank is opened to the atmosphere by the atmosphere release means when the opening / closing means is opened after the adjustment.   2. The image forming apparatus according to claim 1, wherein the recording head side is set to a positive pressure when the opening / closing means is opened after the negative pressure generating chamber is brought into a negative pressure state.   3. The image forming apparatus according to claim 1, wherein the negative pressure generating chamber is formed of an elastically deformable tube member. 4.   3. The image forming apparatus according to claim 1, wherein the negative pressure generating chamber is formed of a bellows-like member.   6. The image forming apparatus according to claim 1, wherein the opening / closing means is closed and the negative pressure generating chamber is in a negative pressure state before performing the maintenance / recovery operation of the recording head. Image forming apparatus.

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