JP2011143614A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem in which it takes time for initial filling of ink since ink supply from a main tank to a sub-tank and stop of the supply are repeated. <P>SOLUTION: The image forming apparatus includes a main tank 91; a sub-tank 81 including a pack 83 the internal capacity of which is changed; an upper limit sensor 183 which detects a liquid quantity in the pack 83; and a control means which controls, when supplying ink from the main tank 91 to the sub-tank 81, the supply quantity from the main tank 91 to the sub-tank 81 according to the detection result of the upper limit sensor 183. When initial filling operation is performed, the control means does not use the detection result of the upper limit sensor 183 to control the ink supply from the main tank 91 to the sub-tank 81. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to an initial filling operation in an image forming apparatus including a liquid discharge head that discharges droplets.

  As an image forming apparatus such as a printer, a facsimile, a copying machine, a plotter, or a complex machine of these, for example, a liquid discharge recording type image forming using a recording head composed of a liquid discharge head (droplet discharge head) that discharges ink droplets. As an apparatus, an ink jet recording apparatus or the like is known. 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 discharge recording method is an apparatus that forms an image by discharging 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 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). “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, resins and the like are also included. In addition, the “image” is not limited to a planar one, but includes an image given to a three-dimensionally formed image, and an image formed by three-dimensionally modeling a solid itself.

  As an ink supply method in such an ink jet recording apparatus used as an image forming apparatus, a sub tank (also synonymous with a buffer tank, a head tank, etc.) is disposed on the recording head side, and a main tank is disposed on the apparatus main body side. A system is known in which ink is replenished and supplied from the main tank to the sub tank, and ink is supplied from the sub tank to the recording head.

  In such an ink supply system, regarding initial filling for initially filling ink into an ink supply path, for example, Patent Document 1 discloses a main ink tank storing ink, opening / closing means for opening and closing piping, and ink. It has a bag-like sub ink tank that temporarily stores and a recording head, and fills the flow path with a negative pressure using the operation of crushing the opening and closing means and the sub ink tank. It is disclosed that air in the flow path from the recording head to the opening / closing means through the sub ink tank is discharged, and air in the flow path from the opening / closing means to the main ink tank is discharged by the next negative pressure action. Has been.

  Further, Patent Document 2 discloses a liquid feeding step for feeding ink from a main tank to a bag-shaped subtank whose volume can be changed, and a subtank from an ink nozzle of an inkjet head after closing the downstream end of the first ink conduit. A suction process for sucking air and ink inside, and after releasing the blockage of the first ink conduit, sucking ink from the ink nozzle while feeding ink from the main tank, and a predetermined amount of ink into the ink flow path It is disclosed to perform a filling step for filling.

Japanese Patent No. 4009821 JP 2003-170607 A

  By the way, when the sub tank is provided with a liquid storage member such as an ink bag having flexibility, the detection means for detecting the ink amount of the liquid storage member in order to control the ink supply amount from the main tank to the sub tank. It is necessary to have.

  Therefore, when the initial filling operation for filling the supply path from the main tank to the head with ink is performed, the ink supply from the main tank to the sub tank is stopped when the ink capacity of the sub tank becomes full. When the ink supply is performed and the ink capacity of the sub tank decreases, the ink supply from the main tank to the sub tank is resumed, so that the ink supply / stop from the main tank to the sub tank is frequently repeated.

  Therefore, there arises a problem that the time required for the initial filling operation becomes long.

  The present invention has been made in view of the above problems, and an object thereof is to shorten the time of the initial filling operation.

In order to solve the above problems, an image forming apparatus according to the present invention includes:
A liquid discharge head for discharging droplets;
A main tank for storing liquid to be supplied to the liquid discharge head;
A liquid storage member that changes the internal volume for storing the liquid supplied from the main tank; and a detection unit that detects the amount of liquid in the liquid storage member, and is disposed on the liquid discharge head side from the liquid storage member. A sub tank for supplying the liquid;
Control means for controlling the amount of liquid supplied from the main tank to the sub-tank according to the detection result of the detection means when supplying the liquid from the main tank to the sub-tank. When performing, the control is performed to supply the liquid from the main tank to the sub tank without using the detection result of the detection means.

  Here, the liquid in the main tank may be pressurized and supplied to the sub tank.

  A plurality of liquid discharge heads; distribution means for distributing liquid to each liquid discharge head; a circulation path for circulating liquid between the liquid discharge head and the distribution means; and the distribution from the liquid discharge head A circulation pump for feeding the liquid in the direction toward the means, and the liquid can be circulated when performing the initial filling operation.

  According to the liquid discharge head unit of the present invention, when the initial filling operation is performed, the control for supplying the liquid from the main tank to the sub tank is performed without using the detection result of the detecting means for detecting the liquid amount of the sub tank. Therefore, the number of times that the supply and stop of the liquid from the main tank to the sub tank is repeated is reduced, and the time required for the initial filling can be shortened.

1 is a schematic front view illustrating the 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 explanatory drawing with which it uses for description of the ink supply system of the apparatus. It is side surface explanatory drawing of the subtank of the apparatus. It is a perspective explanatory view of the sub tank. It is a block explanatory drawing explaining the outline | summary of the control part of the apparatus. It is a flowchart with which it uses for description of the initial filling sequence control processing by the control part. It is a flowchart with which it uses for description of the process which similarly follows FIG. It is also a timing chart. Similarly, it is a state transition diagram. Similarly, it is a state transition diagram. Similarly, it is a state transition diagram. Similarly, it is a state transition diagram. It is a flowchart with which it uses for description of a main tank constant pressure control process. It is a flowchart with which it uses for description of a sub tank ink replenishment control process. It is a flowchart with which it uses for description of the air discharge control processing in a distributor. It is a flowchart with which it uses for description of the process which similarly follows FIG. It is explanatory drawing of the ink supply system with which it uses for description of other embodiment of this invention. It is principal part explanatory drawing of the state which cut | disconnected the joint member. It is a schematic explanatory drawing of a joint member.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. First, an example of an image forming apparatus including a liquid discharge head unit 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 that includes a head module 51 that constitutes a recording head that discharges and prints droplets on a sheet P that is transported by the transport unit 4. The head cleaning device 6, which is a maintenance / recovery mechanism that performs maintenance / recovery of each head of the image forming unit 5 after completion of printing or at a required timing, a conveyance guide portion 7 that opens and closes the head cleaning device 6, An ink tank unit 8 composed of a sub tank that supplies ink to the head module 51, and a main unit that supplies ink to the ink tank unit 8 And a click unit 9.

  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 driving roller 41A, a transport driven roller 41B, and an endless transport belt 43 wound around these rollers 41A and 41B. A plurality of suction 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 41A 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> B and the transport guide rollers 42 </ b> A and 42 </ b> B rotate following the transport belt 43. Further, an empty discharge cleaning device 45 that removes empty discharge droplets attached to the conveyor belt 43 by empty discharge is disposed below the transfer 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.

  The image forming unit 5 is a head module (recording head) in which a plurality of heads for discharging droplets and a liquid discharge head unit (hereinafter referred to as “head unit”) 101 according to the present invention in which head tanks are integrated are arranged in a line. Units) 51A, 51B, 51C, and 51D are arranged along the sheet conveyance direction and attached to the line base member 52.

  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.

  Distributing tanks (hereinafter referred to as “distributors”) 54 serving as distributing means for supplying ink to the respective head units 101 are arranged on the upper side of the head modules 51 for each head module 51. Are connected by a tube 55. A sub tank 81 is disposed upstream of the distributor 54 and connected via a supply tube 82. A main tank 91 for storing ink is disposed on the upstream side of the sub tank 81, and the main tank 91 and the sub tank 81 are connected by a supply path by a supply tube 92.

  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 (head cleaning device) 6 includes four rows of cleaning units 61 </ b> A to 61 </ b> D corresponding to each head module 51 of the image forming unit 5, and one cleaning unit 61 corresponds to each head module 51. A cap member 62 for capping the nozzle surface corresponding to the head 101 and a wiping member (wiper member) 64 for wiping the nozzle surface are formed. 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 63 </ b> A to 63 </ b> D that are suction units for sucking ink from the nozzles with the cap member 62 capping the nozzle surface of the head unit 101 are arranged.

  In this image forming apparatus, after the printing is finished, the ink is sucked from the nozzles while the nozzle surface of each head unit 101 of the head module 51 that discharges droplets is capped by the cleaning unit 61, or the head module When the ink adhering to the nozzle surface of each head unit 101 is cleaned with a wiping member, as shown in FIG. 1, after the printing is stopped, the entire transport unit 4 is moved in the direction of arrow B with the transport driven roller 41B as a fulcrum. By rotating and making the space between the image forming unit 5 larger than that at the time of image formation, a space for moving the image forming unit 5 is secured. At this time, the conveyance guide plate 71 of the conveyance guide portion 7 disposed on the upper portion of the head cleaning device 6 is also rotated upward in the direction of arrow C at the fulcrum 72, and the upper portion of the head 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 (arrow A direction), is stopped above the head cleaning device 6, and is cleaned. 61 rises and shifts to the cleaning operation (maintenance recovery operation) of each head module 51.

Next, details of the ink supply system of this image forming apparatus will be described manually with reference to FIGS.
The ink supply system of the image forming apparatus mainly includes a main tank 91, a sub tank 81, a distributor 54, and a head unit 101. The ink in the main tank 91 is supplied to the sub tank 81 via the supply tube 92, supplied from the sub tank 81 to the distributor 54 via the supply tube 82, and distributedly supplied from the distributor 54 to each head tank 101 via the supply tube 55. Is done. Due to the water head difference (-20 to -70 mmAq) between the sub tank 81 and the nozzle surface of the head unit 101, a negative pressure appropriate to hold the meniscus of the nozzle of the head unit 101 is generated. The head unit 101 includes a head 201 that discharges droplets and a head tank 202 that supplies ink to the head 201.

  The main tank 91 is pressurized with air by a pressurizing pump 94 (P1), and the pressure sensor 95 (S1) is controlled to a predetermined pressure. By this air pressurization, the ink inside is pushed out to the sub tank 81 side. The main tank 91 is provided with an electromagnetic valve 95 (S1) for releasing the atmosphere and a pressure sensor 96 (S1). When the pressure exceeds a predetermined level, the atmosphere is released to the atmosphere.

  An electromagnetic valve (ink supply valve) 93 (V1) is interposed in the supply path from the main tank 91 to the sub tank 81, and supply and stop can be controlled by opening and closing the electromagnetic valve 93.

  The sub tank 81 is constituted by a pack type sub tank. That is, the sub tank 81 is configured by storing a pack (ink bag) 83 capable of changing the volume having flexibility to store ink in the sealed case 84. The pack-type sub-tank prevents ink from directly contacting the atmosphere to prevent the ink from increasing in viscosity due to water evaporation, and also maintains a constant amount of dissolved oxygen in the ink to prevent bubbles from accumulating in the head unit 101. be able to.

  A pressure pump 85 that pressurizes a space 81A between the pack 83 and the case 84 is connected to the sub tank 81 via a chamber 86 (connected by a tube pump). Further, an electromagnetic valve 87 (V2) for opening and closing the path is provided between the space 81A and the chamber, and an electromagnetic valve 88 (Va2) for opening to the atmosphere and a pressure sensor 89 (S2) are provided for the chamber 86. ing.

  Further, a filler (displacement member, detection member) 181 that displaces following the pack 83 is provided in the sub tank 81 in order to detect the amount of liquid in the pack 83, and the filler 181 is provided at the lower limit on the outside of the case 84. A lower limit sensor 182 that detects that the filler 181 is in the position and an upper limit sensor 183 (Sf2) that detects that the filler 181 is in the upper limit position are provided. When the lower limit sensor 182 detects the filler 181, the ink supply valve 93 is opened to supply ink, and when the upper limit sensor 183 detects the filler 181, the ink supply valve 93 is closed to stop the ink supply. Ink supply from the main tank 91 to the sub tank 81 is controlled.

  Further, the above-described pressurizing pump 85, solenoid valve 88, and pressure sensor 89 pressurize the maintenance and recovery of the nozzles of the head unit 101 when the air bubbles accumulated in the distributor 54 are discharged from the exhaust port (atmosphere release path) 155. This is used when the method is used. For example, when discharging bubbles accumulated in the distributor 54, the internal liquid level is detected by the detection needle (liquid level detection sensor) 157 (S3), and it is determined that bubbles are mixed when the liquid level drops. Perform bubble discharge operation. At this time, the bubble discharge valve (solenoid valve) 156 (V3) is opened simultaneously with the pressurization by the pressurization pump 85 of the sub tank 81 to push out the bubbles from the exhaust port 155.

  Further, in the case of pressurization for maintaining and recovering the nozzle of the head unit 101, the inside of the chamber 86 is increased to a predetermined pressure by the pressurizing pump 85, and then the electromagnetic valve 87 (V2) is opened to apply pressure to the space 81A of the sub tank 81. By applying it at once, air pressure is suddenly applied to the pack 83 and ink is pushed out to the head unit 101 side.

  A supply tube 55 for supplying ink is connected between the head tank 202 of the head unit 101 and the distributor 54. In addition, a discharge tube 56 for discharging ink is connected to the head tank 202 of each head unit 101, and each discharge tube 56 is combined into one by a circulation path (circulation manifold) 57, via a circulation pump 58. Connected to the distributor 54.

  When ink and bubbles in the head 201 and the head tank 202 are sucked out, the circulation pump 58 sucks the ink and bubbles back to the distributor 54, separates the bubbles and ink in the distributor 54, and removes only the bubbles into the air discharge port 155. To drain.

  An electromagnetic valve 65 (Vi) for switching the suction cap member 62 is provided between the suction pump 63 and the cap member 62 for capping the nozzle surface of the head unit 101 of the head cleaning device 6 (Mi). ing.

Next, details of the sub-tank will be described with reference to FIGS. 4 is a side explanatory view of the sub tank, and FIG. 5 is a perspective explanatory view.
The sub tank 81 has the pack 83 in a vertically placed state, and the rotation center 181a of the filler 181 is located on the lower side, and the upper limit sensor 183 and the lower limit sensor 182 for detecting the amount of displacement of the tip end of the filler 181 are located outside the case 84. It is arranged on the upper side.

  Here, the filler 181 has a filler contact portion 181b in contact with the surface of the pack 83 so that it can detect that the pack 83 is full of ink as shown by the solid line and ink empty as shown by the broken line. Following the displacement of the outer surface of the pack 83, it is displaced to the position shown by the solid line and the position shown by the broken line. The tip 181c of the filler 181 is formed in a wide surface so that it can be easily detected by the upper limit sensor 183 and the lower limit sensor 182 so that the filler 181 is reliably detected.

  In this case, the center of gravity of the filler 181 is at the position of the filler contact portion 181b with respect to the rotation center 181a of the filler 181, and the filler contact portion 181b is in the direction of the pack 83 with respect to the vertical line of the rotation center 181a ( The filler 181 is configured to fall in the direction of the pack 83, and the filler contact portion 181 b is always in contact with the outer surface of the pack 83.

  Since the swelling of the pack 83 when ink is in the pack 83 is below the center line 184 in the vertical direction of the pack 83, the filler contact portion 181b is in contact with this portion. .

  Further, the positional relationship among the rotation center 181a, the filler contact portion 181b, and the filler tip 181c of the filler 181 is formed so that the filler contact portion 183b is close to the filler rotation center 181a and far from the filler tip 181c. Thus, the displacement amount of the pack 83 is obtained as a large displacement amount at the filler tip 181c.

  Further, as shown in FIG. 5, the filler contact portion 181 b has a larger area than the other part of the filler 181 and stably contacts the outer surface of the pack 83.

  In the upper part of the pack 83, there are provided an ink supply port 185 for supplying ink fed from the main tank 91, and an ink supply port 186 for supplying ink to the distributor 54 (head unit side). By providing the ink supply port 186 at the top of the pack 83, even if air enters from the main tank 91 side and enters the pack 83, the air can easily escape from the ink supply port 186 to the distributor 54 side.

Next, an outline of a control unit in this image forming apparatus will be described with reference to a block explanatory diagram of FIG.
The control unit 500 includes a main control unit (system controller) 501 composed of a microcomputer, an image memory, a communication interface, and the like that also serve as control means for controlling the initial filling operation in the present invention that controls the entire image forming apparatus. ing. The main control unit 501 sends print data to the print control unit 502 in order to form an image on a sheet based on image data transferred from an external information processing apparatus (host side) and various command information.

  Based on the print data signal received from the main control unit 501, the print control unit 502 generates data for driving pressure generating means for ejecting droplets from each head 201 of the recording head unit 101, Various signals necessary for the transfer of the data and confirmation of the transfer are transferred to the head driver 503, and a storage unit as drive waveform data storage means, a D / A converter for D / A converting the drive waveform data, and It includes a drive waveform generation unit composed of a voltage amplifier, a current amplifier, etc., and a selection means for selecting a drive waveform to be given to the head driver 503, and is composed of one drive pulse (drive signal) or a plurality of drive pulses (drive signal). A drive waveform is generated and output to the head driver 503 to drive and control each head 201.

  Further, the main control unit 501 drives and controls a sheet feed motor 505 that moves the conveyor belt 43 in a circular manner via a motor driver 504.

  Further, the main control unit 501 drives (opens and closes) the electromagnetic valve group 506 via the driver 505 and controls the pump group 508 via the driver 507. The electromagnetic valve group 506 includes the above-described electromagnetic valves 58, 93, 95, 87, 88, 65, 155, and the like, and the pump group 508 includes the above-described pumps 94, 85, 63, and the like.

  Further, the main control unit 501 receives detection signals from a sensor group 509 including various sensors. The sensor group 509 includes the above-described sensors 96, 89, 182, 183, 157, and the like. Also, various information is input / output and display information is exchanged with the operation unit 510.

Next, the initial filling operation in the image forming apparatus configured as described above will be described with reference to the flowcharts of FIGS. 7 and 8, the timing chart of FIG. 9, and the state transition diagrams of FIGS.
<Initial state> (period of circled number 1 in FIG. 9)
First, before performing the initial filling operation, as shown in FIG. 3, the supply flow path from the main tank 91 to the upstream of the head tank 202 is not filled with ink. In this example, the filling liquid 601 is filled in the flow path between the head tank 202 and the head 201 of the head unit 101.

<Ink filling of sub tank, distributor, and head tank> (period of numbers 2 to 4 in FIG. 9)
Therefore, when the main tank 91 is set in the apparatus main body, the initial filling operation is started. With reference to FIG. 7, the air release valve 95 (V1a) of the main tank 91 is closed, and the pressurizing pump 94 (P1) of the main tank 91 is closed. ) Is turned on and main tank constant pressure control (described later) is performed until the pressure sensor 96 (S1) reaches a predetermined pressure.

  Then, the air release valve 156 (V 3) of the distributor 54 is opened, the ink supply valve 93 (V 1) is opened, and the ink 600 is supplied from the main tank 91 to the sub tank 81.

  At this time, even if it is detected that the upper limit sensor 183 (Sf2) of the sub tank 81 is turned on and the pack 83 is filled with ink (the upper limit sensor 182 (Sf2) in FIG. 9 is turned on), The ink 600 continues to be fed without using the detection result of the sensor 183 (Sf2) (ignoring the detection result). In this case, since the swelling of the pack 83 is restricted by the inner surface of the case 84 or the filler 181, the pack 83 is not damaged even if liquid is fed after full detection.

  When the ink 600 is fed to the sub tank 81 in this way, the ink 600 is supplied from the sub tank 81 to the distributor 84. When the ink level in the distributor 54 is detected by the liquid level detection sensor 157 (S3) (sensor S3 is ON), the ink supply valve 93 (V1) from the main tank 91 is closed and the air in the distributor 54 is discharged. The release valve 156 (V3) is closed.

  At this stage, since a tube having a small inner diameter is used as the tube 55 that forms the downstream supply flow path from the distributor 54, the ink 600 is not sent downstream from the distributor 54 (see FIG. 10).

  Next, the ink supply valve 93 (V 1) from the main tank 91 is opened, and the ink 600 is pressurized and supplied to the distributor 54, the head tank 202, and the head 201. At this time, since the filling liquid 601 filled inside from the nozzle of the head 201 drips down to the cap member 62, the suction pump 63 (Pi) is turned on to suck this. At this time, the cap member 62 and the nozzle surface of the head 201 are in a separated state.

  Simultaneously with the pressurization of ink, the circulation pump 58 (P3) is turned on to suck out air and ink remaining in the head tank 202 and return them to the distributor 54.

  After supplying the ink by pressurization for a predetermined time, the ink supply valve 93 (V1) is closed, and after a predetermined time has elapsed, the suction pump 63 (Pi) is stopped.

  At this stage, the filling liquid 601 inside the head tank 201 is substantially replaced with the ink 600 (state shown in FIG. 11).

<Air venting of the head tank and distributor> (Period numbered 5-7 in Fig. 9)
Thereafter, the ink supply valve 93 (V1) from the main tank 91 is opened, the suction pump 63 (Pi) is turned on, and the circulation pump P3 of the distributor 54 is turned on. Then, after a predetermined time elapses, the ink supply valve 93 (V1) is closed, the circulation pump P3 is turned OFF, and after the predetermined time elapses, the suction pump 63 (Pi) is turned OFF. As a result, air is collected in the distributor 54.

  Next, referring to FIG. 8, the air release valve 156 (V3) at the top of the distributor 54 is opened. At the same time, the ink supply valve 93 (V1) is opened to supply the ink under pressure. Further, the suction pump 63 (Pi) is turned on. When the liquid level detection sensor 157 (S3) of the distributor 54 is turned on (the liquid level is detected), the atmosphere release valve 156 (V3) is closed, and the ink supply valve 93 (V1) is also closed after a predetermined time has elapsed. Then, the ink supply is stopped, and the suction pump 63 (Pi) is turned OFF after a predetermined time has passed.

  Thereafter, the pressure pump 85 (P2) of the sub tank 81 is turned on, the atmospheric valve (electromagnetic valve) 88 (V2a) is closed, and the electromagnetic valve 87 (V2) is closed. When the pressure sensor 89 (S2) of the sub tank 81 detects a predetermined pressure, the electromagnetic valve 87 (V2) is opened and the suction pump 63 (Pi) is turned on. That is, the inside of the sub tank 81 is pressurized until the pressure sensor 89 (S2) reaches a predetermined pressure, and when the predetermined pressure is reached, the electromagnetic valve 87 (V2) is opened and air is sent into the case 84 of the sub tank 81 all at once. Pressurize. Also at this time, since ink drips from the nozzles of the head 201, the suction pump 63 (Pi) is turned on to suck the ink in the cap member 62.

  Thereafter, when the upper limit sensor 182 (Sf2) detects the upper limit (becomes a predetermined output value), the pressurizing pump 85 (P2) is turned off and the atmospheric valve (solenoid valve) 88 (Va2) is opened. Then, after a predetermined time has elapsed, the suction pump 63 (Pi) is turned off.

  When the ink amount upper limit sensor (53) detects the sub tank filler (60) or after a predetermined time, the sub tank air release valve (V2a) is opened to stop pressurization.

  In this manner, the air upstream of the filter member 204 of the head tank 202 and the upper part of the distributor 54 is discharged, the ink is discharged from the downstream side of the filter member 204 and the head 101, and the initial filling operation is completed (state of FIG. 12). ).

<Main tank pressurization stop> (period of number 8 in FIG. 9)
Thereafter, the suction pump 63 (Pi) is turned on (reverse rotation), and then the suction pump 63 (Pi) is turned off. Further, the pressurizing pump 94 (P1) for pressurizing the inside of the main tank 91 is stopped, and the air release valve 95 (V1a) is opened (see FIG. 13).

Next, the main tank constant pressure control process will be described with reference to the flowchart of FIG.
First, the atmospheric valve 95 (solenoid valve) (V1a) of the main tank 91 is opened, and when the pressure sensor 96 (S1) detects the lower limit value of the predetermined pressure or less, the pressure pump 94 (P1) is turned on to turn on the main tank. When the pressure sensor 96 (S1) detects a pressure equal to or higher than the upper limit value of the predetermined pressure, the pressure pump 94 (P1) is turned off to stop the pressurization of the main tank 91. This process is repeated until the end of the constant pressure control of the main tank 91 is instructed. When the constant pressure control is to be ended, the atmospheric valve (solenoid valve) 95 (Va1) is opened to release the atmosphere, and then the constant pressure control process is ended.

Next, the ink replenishment control process for the sub tank will be described with reference to the flowchart of FIG.
First, when the lower limit sensor 182 (Sf2) of the sub tank 81 becomes equal to or lower than the predetermined output lower limit value (the ink amount is equal to or lower than the lower limit value), the electromagnetic valve 93 (V1) is opened to supply ink from the main tank 91 to the sub tank 81. When the upper limit sensor 183 (Sf2) is equal to or higher than the predetermined output upper limit value (the ink amount is equal to or higher than the upper limit value), the electromagnetic valve 93 (V1) is closed to stop the ink supply from the main tank 91 to the sub tank 81. This process is repeated until the ink supply control is completed.

Next, the distributor air discharge process will be described with reference to the flowcharts of FIGS. 16 and 17.
First, referring to FIG. 16, when the discharge control is started and the liquid level sensor 157 (S3) is OFF, the atmospheric valve (electromagnetic valve) 88 (Va2) of the sub tank 81 is closed, and the pressurizing pump 85 ( P2) is turned on, the solenoid valve 156 (V3) of the distributor 54 is opened, and the suction pump 63 (Pi) is turned on. Thereby, since the ink is supplied from the sub tank 81 to the distributor 54, it is determined whether or not the liquid level sensor 157 (S3) is turned on.

  Here, if the liquid level sensor 157 (S3) is not ON, it is determined whether or not the lower limit sensor 182 (Sf2) of the sub tank 81 is equal to or less than a predetermined output lower limit value (the ink amount is equal to or less than the lower limit value). When 182 (Sf2) is below the predetermined output lower limit value, the atmospheric valve (solenoid valve) 88 (Va2) of the sub tank 81 is opened, the pressurizing pump 85 (P2) is turned off, and the solenoid valve 156 (V3) of the distributor 54 is opened. Is closed, and the ink supply valve 93 (V1) is opened to supply ink from the main tank 91 to the sub tank 81.

  When the lower limit sensor 182 (Sf2) becomes equal to or higher than the predetermined output upper limit value, the ink supply valve 93 (V1) is closed and the ink supply from the main tank 91 to the sub tank 81 is stopped. Thereafter, the atmospheric valve (solenoid valve) 88 (Va2) of the sub tank 81 is closed, the pressurizing pump 85 (P2) is turned on, and the solenoid valve 156 (V3) of the distributor 54 is opened to supply ink from the sub tank 81 to the distributor 54. To do.

  On the other hand, if the liquid level sensor 157 (S3) is ON, the process proceeds to the process shown in FIG. 17, and the atmospheric valve (solenoid valve) 88 (Va2) of the sub tank 81 is opened and the pressurizing pump 85 (P2). Is turned OFF and the solenoid valve 156 (V3) of the distributor 54 is closed, and then the suction pump 63 (Pi) is turned OFF.

  The above-described processing is repeated until the main tank constant pressure control is completed.

Next, a second embodiment of the present invention will be described with reference to a schematic explanatory diagram of FIG.
Here, the end of the initial filling is managed by the amount of ink in the waste liquid tank. That is, in the first embodiment, information on completion of initial filling is managed at a predetermined time, whereas in the configuration of the phon embodiment, management is performed based on the amount of ink dripping from the nozzles of the head 201. To do.

  The ink dripping from the nozzle of the head 201 onto the cap member 82 is sent to the waste liquid tank 67 by the suction pump 63 (Pi). In the waste liquid tank 67, an initial filling ink amount detection sensor 68 and a waste liquid tank full detection sensor 69 are provided at respective height positions in order to detect the amount of ink (waste liquid amount) inside.

  The initial filling ink amount detection sensor 68 is located in the vicinity of the lower surface of the waste liquid tank 67, and the total ink amount that has passed through all the heads 201 mounted on the machine at the time of initial filling is approximately the amount discharged to the waste liquid tank 67. I can grasp. If the amount of ink that has passed through the head 201 is equal to or greater than the predetermined amount, it is confirmed in advance that the nozzles of all the heads 201 are filled with ink. It can be determined whether or not.

  When the waste liquid tank full detection sensor 69 detects waste liquid, since the waste liquid tank 67 is full of waste liquid (waste ink), information for prompting replacement of the waste liquid tank (for example, service man call) is displayed on the operation panel or the like. Display.

Next, head replacement will be described with reference to FIGS. FIG. 19 is a main part explanatory view in a state where the joint member is cut off, and FIG. 20 is a schematic explanatory view of the joint member.
In the image forming apparatus described above, the supply tube 55 and the discharge tube 56 that connect the distributor 54 and the head tank 202 of the head unit 101 are configured to be connected and separated by the joint member 110. Thus, when the head unit 101 is replaced, the supply channel and the discharge channel are separated from the joint member 110, and the head unit 101 is replaced with a new head unit 101. By interposing the joint member 110, the head unit 101 can be replaced even in a state where ink is contained in the flow path.

  When the head unit 101 is replaced, air slightly enters the supply flow path due to the replacement operation, and thus an operation of discharging the ink from the head 201 is required as in the initial filling.

  Also at this time, it is possible to perform the ink supply operation ignoring the ink amount detection control of the sub tank 81 by performing the above-described initial filling operation. As a result, the time for sending ink to the head 201 can be shortened, and as a result, the work time required for head replacement can be shortened. In other words, the “initial filling operation” in the present invention means an operation of filling ink (liquid) in the head.

  As shown in FIG. 20, the joint member 110 mainly includes a component having a supply needle 191 and a component having a rubber plug 195. When the supply needle 191 is inserted into the rubber stopper 195, the distributor 54 and the head unit 101 communicate with each other through a hole 192 provided at the tip of the supply needle 191 (FIG. 20B).

  When the supply needle 191 is removed from the rubber plug 195, the cover member 193 is pushed by the biasing force of the spring 198 to seal the hole 192 so that ink does not leak from the hole 192 of the supply needle 191. (FIG. 20 (a)).

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

1 Device body 4 Transport unit (transport section)
5 Image forming unit 6 Cleaning device (maintenance and recovery mechanism)
7 Transport guide 8 Ink tank unit (sub tank unit)
9 Main tank unit 51 Head module (recording head unit)
54 Distribution tank (distribution member)
81 Sub tank 91 Main tank (ink cartridge)
101 Head unit 201 Head 202 Head tank

Claims (3)

A liquid discharge head for discharging droplets;
A main tank for storing liquid to be supplied to the liquid discharge head;
A liquid storage member that changes the internal volume for storing the liquid supplied from the main tank; and a detection unit that detects the amount of liquid in the liquid storage member, and is disposed on the liquid discharge head side from the liquid storage member. A sub tank for supplying the liquid;
Control means for controlling the amount of liquid supplied from the main tank to the sub-tank according to the detection result of the detection means when supplying the liquid from the main tank to the sub-tank. And performing control to supply liquid from the main tank to the sub tank without using the detection result of the detecting means.   The image forming apparatus according to claim 1, wherein the liquid in the main tank is pressurized and supplied to the sub tank.   A plurality of the liquid discharge heads, a distribution means for distributing liquid to each liquid discharge head, a circulation path for circulating the liquid between the liquid discharge head and the distribution means, and the liquid discharge head to the distribution means 3. The image forming apparatus according to claim 1, further comprising a circulation pump configured to send the liquid in a direction toward which the liquid is circulated when the initial filling operation is performed.

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