JP2008168563A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that the discharge of air bubbles entering an air bubble catching section by closing a channel opening and closing valve installed between an ink tank and the air bubble catching section and decompressing a downstream side supply tube makes the air bubbles intrude into the interior of a head from nozzles and causes a defective discharge. <P>SOLUTION: The image forming device includes a main tank 9 storing a liquid supplied to a recording head 14, a sub tank 15 supplying the liquid supplied from the main tank 9 through a liquid supply route 51 to the recording head 14, a detection means 53 to detect the mounting of the main tank 9, a cap 41 to seal the nozzle surface of the recording head 14, a discharge route opening and closing means 52 to open or close the air bubble discharge route 46 branched from the liquid supply route 51, a pressurizer 42 delivering the liquid from the main tank 9 to the liquid supply route 51, and a main control section 61 to control the lifting and lowering of the cap 41, the opening and closing of the discharge route opening and closing means 52, the pressurization and stop of the pressurizer 42 on the basis of the result of detection of the detection means 53. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus including a liquid discharge head.

  In general, as an image forming apparatus that combines a printer / fax / copier or a combination of these functions, for example, a liquid including a recording head constituted by a liquid discharge head (droplet discharge head) that discharges droplets of a recording liquid (liquid). While using a discharge device to convey a medium (hereinafter also referred to as “paper”, the material is not limited, and a recording medium, a recording medium, a transfer material, recording paper, and the like are also used synonymously) Some of them perform image formation (recording, printing, printing, and printing are also used synonymously) by attaching a recording liquid (hereinafter also referred to as ink) as a liquid to a sheet.

  The image forming apparatus means an apparatus for forming an image by discharging a liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc. The term “not only” 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. Further, the liquid ejection apparatus means an apparatus that ejects liquid from a liquid ejection head, and is not limited to an apparatus that performs image formation.

  In such a liquid discharge type image forming apparatus, the recording liquid is supplied to the recording head in such a manner that a recording liquid cartridge, which is a liquid liquid storing means for storing the recording liquid in a carriage on which the recording head is mounted, is detachable. And a system for supplying the recording liquid from the recording liquid cartridge to the recording head and a small-capacity head tank (also referred to as a sub-tank) as second liquid storage means for supplying the recording liquid to the recording head on the carriage. Equipped with a large-capacity recording liquid cartridge (main tank), which is the first liquid storage means, is replaceably mounted on the apparatus main body, and the head tank is supplied with recording liquid (ink) from the recording liquid cartridge on the apparatus main body. Is known.

  By the way, in the structure which can replace | exchange a main tank, when a bubble enters into a liquid supply path when connecting a main tank to a supply flow path (liquid supply path), fluid resistance will increase and it will be from a main tank. Insufficient liquid supply occurs to cause a printing defect.

Therefore, Patent Document 1 includes a bubble capturing unit that captures bubbles flowing in ink in an ink supply tube that supplies ink to an ink supply tube from an ink tank that stores ink, and the bubbles that have entered the bubble capturing unit are separated from the ink tank. It is described that the flow path opening / closing valve installed between the bubble capturing portions is closed and the ink supply tube on the downstream side of the valve is decompressed to be discharged.
JP 2004-188664 A

In addition, Patent Document 2 is provided with a variable volume means for reducing the volume of the ink supply path during the mounting operation of the removable ink cartridge and returning the reduced volume to the original state when the mounting is completed. The ink cartridge is equipped with an ink outlet plug that communicates with the recording head as a configuration of the ink cartridge, and is equipped with an ink pack that accommodates ink and can be deformed by air pressure. Japanese Patent Application Laid-Open No. 2004-133867 discloses that the device stored in the non-volatile memory is detected by the cartridge detachment detecting unit that detects the detachment of the ink cartridge. Each of them describes whether or not to supply ink according to the state.
JP-A-06-000968 JP 2003-200590 A JP 2000-025245 A Japanese Patent Laying-Open No. 2005-081596

  However, as described in Patent Document 1 described above, air bubbles that have entered the bubble trapping section are closed by a flow path opening / closing valve installed between the ink tank and the bubble trapping section, and ink is supplied downstream from the valve. In the configuration of discharging by depressurizing the tube, there is a problem that bubbles enter the inside of the head from the nozzles of the recording head, and ejection defects (bending in the ejection direction or ejection failure) occur due to the bubbles.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of reliably removing bubbles mixed in a liquid supply path when a main tank is replaced.

  In order to solve the above problems, an image forming apparatus according to the present invention includes a liquid discharge head that discharges liquid droplets, a first liquid storage unit that stores a liquid to be supplied to the liquid discharge head, and the first liquid storage. In the image forming apparatus provided with the second liquid storage unit that temporarily holds the liquid supplied from the unit via the liquid supply path and supplies the liquid to the liquid discharge head, the first liquid storage unit is mounted. Detecting means for detecting the nozzle, sealing means for sealing the nozzle surface of the liquid discharge head, discharge path opening / closing means for opening / closing a bubble discharge path for discharging bubbles branched from the liquid supply path, and first liquid storage means Pressurizing means for feeding liquid from the liquid supply path to the liquid supply path, and control means for controlling the operation of the sealing means, the discharge path opening / closing means and the pressurizing means based on the detection result of the detecting means. It was formed.

  Here, after the sealing means seals the nozzle surface of the liquid ejection head based on the detection result of the detection means, the discharge path opening / closing means opens the bubble discharge path, and finally the pressurizing means It can be set as the structure which controls to send out a liquid from the 1 liquid storage means to a liquid supply path | route. Further, the control means, based on the detection result of the detection means, after the sealing means seals the nozzle surface of the liquid discharge head, the pressurizing means causes the liquid to be sent from the first liquid storage means to the liquid supply path, Finally, the discharge path opening / closing means can control to open the bubble discharge path.

  In addition, the control means can be configured to cause the pressurizing means to perform an operation of intermittently applying a pressure a plurality of times to the supply path from the first containing means to send it out. Further, the bubble discharge path may be provided at a higher water head position than the supply path. Further, the bubble discharge path can lead to a waste liquid storage means for storing the waste liquid.

  Also, a configuration is provided that includes a plurality of first liquid storage units that store liquids of different colors, and a pressurizing unit that simultaneously or selectively feeds the liquids of the respective colors from the first liquid storage units of the respective colors to the liquid supply path. It can be.

  The discharge path opening / closing means has an elastically deformable member that forms at least a part of the bubble discharge path and a compression member that compresses the elastically deformable member, and is elastically deformable by the compression member. The bubble discharge path can be closed by pressing the member.

  The sealing unit may be a capping unit that seals the nozzle surface of the liquid ejection head outside the printing region. Moreover, the bubble discharge path can be configured to include a bubble capturing unit that captures bubbles. Further, the control means sets the pressurizing means so that the amount discharged from the bubble discharge path is substantially the same as the flow path volume from the connection portion of the first containing means and the liquid supply path to the discharge port of the bubble discharge path. It can be set as the structure controlled.

  According to the image forming apparatus of the present invention, the detection unit that detects that the first liquid storage unit is mounted, the sealing unit that seals the nozzle surface of the liquid discharge head, and the liquid supply path are branched. A discharge path opening / closing means for opening and closing a bubble discharge path for discharging bubbles, and a pressure means for sending liquid from the first liquid storage means to the liquid supply path, and sealing means based on the detection result of the detection means, Since the discharge path opening / closing means and the control means for controlling the operation of the pressurizing means are provided, the bubble discharge path even if bubbles enter the liquid supply path when the replaceable first liquid storage means is replaced. The bubbles can be discharged from the liquid and the liquid can be stably supplied to the liquid discharge head continuously.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. An example of an image forming apparatus to which the present invention is applied will be described with reference to FIGS. FIG. 1 is an explanatory perspective view of the image forming apparatus as viewed from the front side, FIG. 2 is a schematic configuration diagram illustrating the entire configuration of a mechanism section of the apparatus, and FIG.

  As shown in FIG. 1, the image forming apparatus includes an apparatus main body 1, a paper feed tray 2 for loading paper as a recording medium attached to the apparatus main body 1, and an image attached to the apparatus main body 1 to record an image ( And a discharge tray 3 for stocking the formed paper. Further, one end of the front surface 4 of the apparatus main body 1 protrudes forward from the front surface 4 and is lower than the upper surface 5. A tank loading unit 6 is provided, and an operation unit 7 such as operation keys and a display is arranged on the upper surface of the ink tank loading unit 6. The ink tank loading section 6 has a front cover 8 that can be opened and closed for detaching the main tank 9 as the first liquid storage means.

  As shown in FIGS. 2 and 3, the carriage 13 is slidably held in the main scanning direction by a guide rod 11 which is a guide member horizontally mounted on left and right side plates (not shown) and a stay 12, and is not shown. The scanning motor moves and scans in the direction indicated by the arrow in FIG.

  The carriage 13 has recording heads 14Y and 14C composed of four liquid ejection heads that eject droplets (ink droplets) of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). , 14M, and 14K (referred to as “recording head 14” when colors are not distinguished) are arranged so that a plurality of ink discharge ports (nozzles) intersect with the main scanning direction and the droplet discharge direction faces downward. ing.

  The present invention does not limit the discharge pressure generating means (actuator means) of the liquid discharge head, and the recording heads 14 (14Y, 14C, 14M, 14K) of each color are used here as the recording heads 14. However, the number of recording heads may be one or less than the number of colors having nozzles that eject ink droplets of each color.

  Further, the carriage 13 is equipped with sub tanks 15 (15Y, 15C, 15M, and 15K) that are second liquid storage means that are liquid containers of the respective colors for supplying the inks of the respective colors to the recording head. Ink is replenished and supplied from the ink tanks 9Y, 9C, 9M, and 9K for the respective colors to the sub tank 15 through a supply tube 16 that constitutes a liquid supply path. Here, the ink tanks 9Y, 9C, 9M, and 9K respectively store yellow (Y), cyan (C), magenta (M), and black (Bk) inks corresponding to the respective colors. The sub tank 15 is a buffer tank that temporarily holds the liquid supplied from the main tank 9 and supplies the liquid to the recording head 14, and may include a negative pressure generating mechanism. The negative pressure generation mechanism may not be provided as in the embodiment.

  On the other hand, as a paper feeding unit for feeding the paper 18 stacked on the paper stacking unit (pressure plate) 19 of the paper feeding tray 3, a half-moon roller (feeding) that separates and feeds the paper 18 from the paper stacking unit 19 one by one. A separation pad 21 made of a material having a large friction coefficient is provided opposite to the paper roller 20 and the paper feeding roller 20, and the separation pad 21 is biased toward the paper feeding roller 20.

  As a transport unit for transporting the paper 18 fed from the paper feed unit on the lower side of the recording head 14, a transport belt 24 for transporting the paper 18 by electrostatic attraction and a paper feed unit A counter roller 34 for transporting the paper 18 fed through the guide 22 while sandwiching it between the transport belt 24 and the paper 18 fed substantially vertically upward is changed by approximately 90 ° and copied onto the transport belt 24. A conveying guide 33 for adjusting the pressure and a tip pressing roller 31 urged toward the conveying belt 24 by a pressing member 32 are provided. In addition, a charging roller 23 that is a charging unit for charging the surface of the transport belt 24 is provided.

  Here, the conveyance belt 24 is an endless belt, and is configured to be looped around the conveyance roller 30 and the tension roller 28 in the belt conveyance direction of FIG. The charging roller 23 is disposed so as to come into contact with the surface layer of the transport belt 24 and to rotate following the rotation of the transport belt 24.

  In addition, a guide member 29 is disposed on the back side of the conveyance belt 24 so as to correspond to a printing area by the recording head 14. The upper surface of the guide member 29 protrudes toward the recording head 14 from the tangent line of two rollers (the conveyance roller 30 and the tension roller 28) that support the conveyance belt 24. As a result, the transport belt 24 is pushed up and guided by the upper surface of the guide member 29 in the printing region, so that highly accurate flatness is maintained.

  A plurality of grooves are formed in the main scanning direction, that is, a direction orthogonal to the conveyance direction on the surface side of the guide member 29 that contacts the back surface of the conveyance belt 24 to reduce the contact area with the conveyance belt 24. The belt 24 can smoothly move along the surface of the guide member 29.

  Further, as a paper discharge unit for discharging the paper 18 recorded by the recording head 14, a separation claw 25 for separating the paper 18 from the conveyance belt 24, a paper discharge roller 26 and a paper discharge roller 27 are provided. The paper discharge tray 3 is provided below the paper discharge roller 26. Here, the height from the sheet discharge roller 26 and the sheet discharge roller 27 to the sheet discharge tray 3 is increased to some extent in order to increase the amount that can be stored in the sheet discharge tray 3.

  A double-sided paper feeding unit 36 is detachably attached to the back surface of the apparatus body 1. The double-sided paper feeding unit 36 takes in the paper 18 returned by the reverse rotation of the transport belt 24, reverses it, and feeds it again between the counter roller 34 and the transport belt 24. A manual paper feed unit 35 is provided on the upper surface of the double-sided paper feed unit 36.

  Further, as shown in FIG. 3, in the non-printing area on one side of the carriage 13 in the scanning direction, air is sent into the main tank 9 and a recovery device 38 for recovering the nozzle state of the recording head 14. A pressurizing device 42 is disposed as pressurizing means for sending ink from the main tank 9 to the supply tube 16 which is a liquid supply path.

  The recovery device 38 stores ink ejected from the nozzles of the recording head 14 by the pressurizing device 42 during nozzle recovery operation of the recording head and waste ink not related to recording ejected before or during recording. A waste ink container 39 and a wiper blade 37 for wiping the nozzle surface are provided.

  A capping device 40 is disposed in the non-printing area on the other side of the carriage 13 in the scanning direction. The capping device 40 includes a cap 41 (41K, 41C, 41M, 41Y) as sealing means for capping the nozzle surface of the recording head 14 to seal the nozzle.

Next, details of the liquid supply system in the image forming apparatus will be described with reference to FIG.
The recording head 14 is integrally provided with a sub tank 15 as second liquid storage means via a filter 43 and is mounted on the carriage 13 as described above. The sub tank 15 is provided with two detection electrodes 44 for detecting the presence or absence of ink, and is provided with an air release means 45 for opening the inside to the atmosphere. The presence or absence of ink can be detected by changing the electric resistance between the two detection electrodes 44 when they are in contact with ink and when they are not in contact with ink.

  A cap 41 is used as a sealing means for sealing the nozzle surface of the recording head 14. Thereby, the moisture retention cap previously installed in the apparatus can be used, and it is not necessary to newly provide a sealing member, and cost can be reduced.

  The main tank 9 as the first liquid storage means stores an ink bag 47 that can be deformed by an external pressure. When the main tank 9 is attached to the apparatus main body, the ink bag 47 is connected to an ink supply path (liquid supply path) 51 (partly constituted by the supply tube 16) via a connection portion 51a. Further, a pressurizing device 42 is connected to the main tank 9 so as to be able to contact and separate. By sending air from the pressurizing device 42 into the main tank 9, the ink bag 47 is crushed and ink is supplied to the ink supply path 51. Ink, which is liquid, is sent out from the bag 47.

  The main tank mounting portion 6 on the apparatus main body side is provided with a main tank mounting detecting means 53 as a detecting means for detecting that the main tank 9 is mounted.

  The main tank 9 is disposed at a position having a predetermined water head difference H with respect to the recording head 14, and generates a negative pressure due to the water head difference to the nozzles of the recording head 14.

  A bubble capturing unit 60 that captures bubbles is provided in the middle of the ink supply path 51, a bubble discharging path 46 that branches from the bubble capturing unit 60 and discharges bubbles is provided, and the bubble discharging path 46 is opened and closed. A discharge path opening / closing means 52 is provided.

  In addition, when a part of the bubble discharge path 46 forms the bubble trapping part 60, when the invasion of the bubble occurs due to a decrease in the sealing performance of the connection part 51a of the main tank 9 and the liquid supply path 51 during operation of the apparatus. However, a small amount of air bubbles can be trapped in the air bubble capturing unit 60, and since the air bubbles do not block the liquid supply path 51, the recording liquid is continuously stably supplied to the liquid ejection head (recording head 14). can do.

  Further, the bubble discharge path 46 is provided at a head position higher than a part of the liquid supply path 51. As a result, when the bubbles that have entered the liquid supply path 51 pass through the branch portion with the bubble discharge path 46, they are guided into the bubble discharge path 46 by the buoyancy of the bubbles and are reliably trapped. Can be discharged.

  The discharge path opening / closing means 52 is an elastically deformable member that forms the bubble discharge path 46, a compression member 49 that presses the elastically deformable member that forms the bubble discharge path 46, and a rotation that rotates the compression member 49. The bubble discharge path 46 is closed when the compression member 49 compresses and crushes the bubble discharge path 46. The other end opening of the bubble discharge path 46 is disposed facing the waste liquid tank 39 as waste liquid storage means.

  In this way, the discharge path opening / closing means for opening and closing the bubble discharge path 46 is constituted by the flow path of the elastic member and the compression member, and the flow path is closed by being elastically deformed by pressing the elastic member. Thus, an on-off valve (open / close switching valve) can be realized with a relatively inexpensive and simple configuration. In addition, it is necessary to newly provide a waste liquid storage section by allowing the discharge side opening of the bubble discharge path to face (communicate with) the waste liquid storage section that is discharged during the maintenance recovery operation of the recording head installed in the apparatus in advance. Cost can be reduced.

Next, a control unit related to the control of the ink supply system will be described with reference to FIG.
The main control unit 61 is a part that controls the entire image forming apparatus that also functions as a control unit according to the present invention, and includes a CPU, a ROM, a RAM, an I / O, a rewritable nonvolatile memory, and the like. .

  The main control unit 61 controls the drive of the pressurizer 42 by driving the drive source of the pressurizer contact / separation mechanism 62 that connects and separates the pressurizer 42 and the main tank 9 via the drive circuit 62. The tank 9 is connected or separated. Further, the air generation drive source (pressure pump) of the pressurizing device 42 is driven and controlled via the drive circuit 64 so that air is sent into the main tank 9 while being connected to the main tank 9.

  The main control unit 61 drives and controls a drive source that rotates the rotation member 50 of the discharge path opening / closing means 52 via the drive circuit 65 and rotates the compression member 49 to open and close the bubble discharge path 46. Let it be done.

  The main control unit 61 drives and controls the drive source of the cap lifting mechanism 67 that lifts and lowers the cap 41 of the recovery device 40 via the drive circuit 66 to raise the cap 41 and seal the nozzle surface of the recording head 14. The operation and the operation of lowering the nozzle 41 of the recording head 14 by lowering the cap 41 are performed. Further, the main control unit 61 drives and controls a drive source that drives the atmosphere release mechanism 45 of the sub tank 15 via the drive circuit 68 to release the inside of the sub tank 15 to the atmosphere.

  In order to perform each drive control, the main control unit 61 receives a detection signal from the main tank mounting detection unit 53 that detects the mounting of the main tank 61, and an ink presence / absence detection unit 69 including the detection electrode 44 of the sub tank 35. A detection signal is input.

Therefore, an initial filling process for initially filling the head with the ink in the image forming apparatus will be described with reference to the flowchart of FIG.
This process is started when an initial filling command is entered. First, it is determined whether or not the main tank 9 is attached to the main tank loading portion 6 based on the detection signal of the main tank attachment detecting means 53 (cartridge attachment). ).

  At this time, if the main tank 9 is attached to the main tank loading section 6, it is determined whether or not the sub tank 15 is out of ink based on the detection signal of the ink presence / absence detecting means 69 (no sub tank ink). If there is no ink, the drive source (actuator) of the atmosphere release mechanism 45 is driven to release the inside of the sub tank 15 to the atmosphere.

  Thereafter, the pressurizing device contacting / separating mechanism 63 is driven and controlled to connect the pressurizing pump of the pressurizing device 42 to the main tank 9, and the pressurizing pump of the pressurizing device 42 is driven to send air into the main tank 9. Let As a result, the ink bag 47 in the main tank 9 is pressurized, the ink is sent out from the ink bag 47 into the ink supply path 51, and the sub tank 15 is filled with ink. Then, when the ink presence / absence detection means 44 of the sub tank 15 outputs a full tank detection signal, the driving of the pressurizing device 42 is temporarily stopped, and the atmosphere release mechanism 45 of the sub tank 15 is closed (sub tank atmosphere cutoff).

  Next, the pressurization device 42 is driven again for a predetermined time (pressurization time measurement) and stopped, so that the inside of the ink tank 9 is pressurized for a predetermined time, and further ink is supplied from the ink bag 47 to within the recording head 14. Is sufficiently filled with ink.

  Thereafter, when a bubble discharge command for discharging bubbles in the bubble discharge channel 46 is entered, the cap 41 is raised to cap the nozzle surface of the recording head 14 and seal the nozzle opening. When the sub tank 35 is not out of ink as a result of the above-described sub tank ink presence / absence determination, the bubble discharge command is entered as it is, and the nozzle surface is capped.

  Next, the rotation member 50 of the discharge path opening / closing means 52 is driven to rotate, and the pressure discharge member 49 that closes the discharge path 46 by rotating the bubble discharge path 46 is rotated to bring the bubble discharge path 46 to the atmosphere. Open (open the bubble discharge valve).

  Then, the pressure pump of the pressure device 42 is driven again, and the ink is sent out from the ink bag 47 into the ink supply path 51, so that bubbles mixed in the ink supply path 51 and the bubble discharge path 46 are mixed. 48 is discharged to the waste liquid tank 39. At this time, the pressurizing time is measured and the driving of the pressurizing device 42 is stopped after a predetermined time has elapsed, and then the rotary member 50 of the discharge path opening / closing means 52 is rotationally driven to rotate the compression member 49 to discharge the bubbles. The bubble discharge path 46 is closed by pressing the passage 46 (bubble discharge valve closed).

  Thereafter, the cap raising / lowering means 67 is driven and controlled to lower the cap 41, and the capping of the nozzle surface of the recording head 14 is released. Thereby, initial filling is completed.

  By performing the initial filling operation control in this way, the ink supply flow path 51 from the main tank 9 to the sub tank 15 can be filled with ink, that is, the ink is continuously and stably supplied to the recording head 14. Therefore, there is no ejection failure due to insufficient supply, and printing can be performed stably.

  As described above, the detection means for detecting that the main tank is mounted, the sealing means for sealing the nozzle surface of the liquid discharge head based on the detection result of the detection means, and the discharge of the bubbles branched from the liquid supply path The discharge path opening / closing means for opening the path, the pressurizing means for supplying the air into the main tank and sending the recording liquid into the liquid supply path to pressurize the liquid in the liquid supply path, and the respective means are controlled. By providing the control means, the liquid can be surely initially filled in the liquid discharge head, and even if the bubbles enter the liquid supply path when the main tank is replaced, the bubbles can be discharged from the bubble discharge path. Thus, the liquid can be stably supplied to the liquid discharge head.

Next, bubble discharge control in the second embodiment of the present invention will be described with reference to FIG.
Here, the execution of this process is started when the bubble discharge command is entered. First, based on the detection signal of the main tank mounting detection means 53, it is determined whether or not the main tank 9 is mounted on the main tank loading unit 6. Determine (cartridge mounted).

  At this time, if the main tank 9 is attached to the main tank loading unit 6, the cap 41 is raised to cap the nozzle surface of the recording head 14 to seal the nozzle opening. Note that if the main tank 9 is not attached as a result of the determination of the attachment of the main tank 9 described above, the process is directly terminated.

  Next, the rotation member 50 of the discharge path opening / closing means 52 is driven to rotate, and the pressure discharge member 49 that closes the discharge path 46 by rotating the bubble discharge path 46 is rotated to bring the bubble discharge path 46 to the atmosphere. Open (open the bubble discharge valve).

  Then, the pressure pump of the pressurizing device 42 is driven to send air into the main tank 9, and ink is sent out from the ink bag 47 into the ink supply path 51, whereby the ink tank 9 is replaced from the bubble discharge channel 46. The air bubbles 48 that have intruded sometimes begin to be discharged into the waste liquid tank 39. At this time, the drive control of the pressurizing device 42 is intermittently driven and stopped to give a shake to the bubbles 48 staying in the ink supply path 51, and the inner wall of the ink supply path 51 by the effect of the shake. The bubble 48 adhering to is made easy to move.

  Thus, by controlling the driving of the pressurizing means (pressurizing device 42) so as to intermittently pressurize the recording liquid in the liquid supply path 51 a plurality of times, the flow of the recording liquid repeatedly occurs and the liquid supply path 51 The bubbles staying inside are shaken and the bubbles easily move away from the inner surface of the liquid supply path 51, so that the bubbles can be discharged more reliably.

  Then, after pressurizing for a predetermined time so that the ink corresponding to the flow path volume from the connecting portion 51 a to the branching portion 51 b of the ink supply path 51 is discharged to the waste ink containing portion 39, the pressurizing device 42. The bubble discharge path 46 is closed by stopping the pressure pump and rotating the compression member 49 again. The amount of recording liquid discharged from the bubble discharge path 46 is substantially the same as the flow volume from the connecting portion 51a of the main tank 9 and the liquid supply path 51 to the discharge port (branch portion 51b) of the bubble discharge path 46. In addition, by controlling the pressurizing device 42, it is possible to reliably discharge bubbles mixed with a small amount of discharged recording liquid out of the liquid supply path 51.

  Thereafter, the cap raising / lowering means 67 is driven and controlled to lower the cap 41, and the capping of the nozzle surface of the recording head 14 is released.

  By performing such control, the bubbles 48 that have entered when the ink tank 9 is replaced can be reliably discharged to the outside.

  In this way, after the sealing means is operated, the discharge path opening / closing means is operated, and finally, the pressurizing means is controlled to operate, so that even if bubbles enter during the replacement of the main tank, Can be reliably discharged, and bubbles can be prevented from entering from the nozzle openings of the liquid discharge head, and the occurrence of printing defects due to defective discharge can be reduced.

Next, bubble discharge control in the third embodiment of the present invention will be described with reference to FIG.
Here, the execution of this process is started when the bubble discharge command is entered. First, based on the detection signal of the main tank mounting detection means 53, it is determined whether or not the main tank 9 is mounted on the main tank loading unit 6. Determine (cartridge mounted).

  At this time, if the main tank 9 is attached to the main tank loading unit 6, the cap 41 is raised to cap the nozzle surface of the recording head 14 to seal the nozzle opening. Note that if the main tank 9 is not attached as a result of the determination of the attachment of the main tank 9 described above, the process is directly terminated.

  Next, the pressurizing pump of the pressurizing device 42 is driven to send air into the main tank 9, a predetermined pressurizing time is measured, and after the predetermined pressurizing time has elapsed, the pressurizing pump of the pressurizing device 42 is stopped. To do. Thereafter, the rotation member 50 of the discharge path opening / closing means 52 is driven to rotate, and the pressure discharge member 49 that closes the discharge path 46 is rotated by pressing the bubble discharge path 46, so that the bubble discharge path 46 is brought to the atmosphere. Open (open the bubble discharge valve).

  By driving the pressurizing device 42, the pressure in the path from the ink tank 9 to the recording head 14 is temporarily increased. Therefore, when the bubble discharge channel 46 is opened to the atmosphere, the animal pressure effect As a result, the ink flow accelerated by the nozzle is ejected vigorously, and minute bubbles are also reliably ejected.

  After that, the bubble discharge path 46 is closed by rotating the compression member 49 again, and the cap raising / lowering means 67 is driven and controlled to lower the cap 41 to release the capping of the nozzle surface of the recording head 14.

  In this way, after the sealing means is operated, the pressurizing means is operated, and finally, the discharge path opening / closing means is controlled to operate, so that the applied pressure in the path from the main tank to the liquid discharge head can be reduced. Since the bubble discharge path is opened in a temporarily raised state, the flow rate of the recording liquid that flows out of the bubble discharge path can be increased, and the fine bubbles that tend to stay in the liquid supply path can be discharged more reliably. Can do.

Next, a fourth embodiment of the present invention will be described with reference to FIGS. 9 is a schematic explanatory view of the ink supply system, and FIG. 10 is a schematic perspective explanatory view of the pressurizing device and the discharge path opening / closing means.
Here, the tubing pump 71 as the pressurizing means and the rotating body 50 constituting the discharge path opening / closing means 52 are driven by the same single drive source motor 57.

  That is, the tubing pump 71 includes a plurality of (here, two) compression members 54 that are rotated by the rotation of the rotation member 55, and the compression member 54 is rotated while being compressed by the compression members 54. And a pressurizing unit that pressurizes the ink bag 47 by feeding air into the main tank 9 by connecting one end of the tube 56 to the main tank 9 so as to be able to contact and separate. It is composed.

  The rotating member 50 of the discharge path opening / closing means 52 that opens and closes the bubble discharge path 46 is connected to the rotating member 55 of the tubing pump 71 via the clutch member 72. Here, when the rotating member 55 rotates in the arrow A direction with respect to the clutch member 72, the rotation of the rotating member 55 is not transmitted to the clutch member 72, and the rotating member 50 does not rotate. In contrast, when the rotating member 55 rotates in the direction opposite to the arrow A direction with respect to the clutch member 72, the rotation of the rotating member 55 is transmitted to the clutch member 72, and the rotating member 50 rotates in the arrow B direction. .

  That is, each of the rotating members 50 and 55 can rotate only in the direction indicated by the arrow A or the arrow B in the drawing. By rotating the motor 57 in the normal direction or the reverse direction, the opening / closing operation of the bubble discharge path 46 and the ink tank are performed. The pressurizing operation in 9 can be switched.

  As a result, the opening / closing control of the bubble discharge path 46 and the pressurization control in the main tank 9 can be realized by one actuator, and the size and cost can be further reduced. It should be noted that the control of discharging air bubbles that enter during initial ink filling and replacement of the ink tank 9 is the same as in the first to third embodiments described above.

Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 11 is a schematic explanatory diagram of an ink supply system.
Here, a bag-like waste liquid container 69 is built in the main tank 9, and the discharge side opening end of the bubble discharge path 46 is connected to the waste liquid container 69.

  This eliminates the need for installing the waste liquid tank 39 dedicated to the bubble discharge path inside the apparatus and reduces the excess space in the main tank 9, and is required when pressurizing the main tank 9 by the tubing pump 71. Time can be shortened. That is, as the ink is consumed, the ink in the ink bag 47 contained in the main tank 9 decreases and the space in the main tank 9 increases accordingly. Although the time for sending and pressurizing gradually increases, the pressurization time can be shortened by using this embodiment. It should be noted that the control of discharging air bubbles that enter during initial ink filling and replacement of the ink tank 9 is the same as in the first to third embodiments described above.

  In each of the above embodiments, the pressurizing means can pressurize the main tank of each color simultaneously or selectively, so that only the liquid supply path of the replaced main tank connection portion can be pressurized. Therefore, the amount of waste liquid discharged together with bubbles can be reduced when bubbles are discharged, and the main tanks for all colors are attached to the image forming apparatus when initially filled. The time for discharging the bubbles in the supply path can be shortened.

  The image forming apparatus according to the present invention is not limited to a printer having a single function configuration, and may be an image forming apparatus having a composite function such as a printer / facsimile / copying. Further, the liquid is not limited to ink.

1 is an explanatory perspective view of an example of an image forming apparatus to which the present invention is applied as viewed from the front side. It is a schematic block diagram explaining the whole structure of the mechanism part of the apparatus. It is principal part plane explanatory drawing of the mechanism part. It is a typical explanatory view of the liquid supply system concerning a 1st embodiment of the present invention. It is a block explanatory drawing of a control part similarly. It is a flowchart with which it uses for description of the initial stage filling by the same control part, and bubble discharge operation control. It is a flowchart with which it uses for description of bubble discharge operation control in 2nd Embodiment of this invention. It is a flowchart with which it uses for description of bubble discharge operation control in 3rd Embodiment of this invention. It is a typical explanatory view of the liquid supply system concerning a 4th embodiment of the present invention. It is a perspective explanatory view of the portion concerning a pressurizing means and a discharge route opening and closing means. It is a typical explanatory view of a liquid supply system concerning a 5th embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Apparatus main body 2 ... Paper feed tray 3 ... Paper discharge tray 6 ... Main tank loading part 9K, 9C, 9M, 9Y ... Main tank (1st liquid storage means)
13 ... Carriage 14 ... Recording head 15 ... Sub tank (second liquid storage means)
39, 69 ... Waste liquid storage part 41K, 41C, 41M, 41Y ... Cap (sealing means)
42 ... Pressurizing device 46 ... Bubble discharge path 47 ... Ink bag 51 ... Liquid supply path (ink supply path)
52 ... Discharge path opening / closing means 53 ... Main tank mounting detection means (detection means)
60 ... Bubble capture unit 61 ... Main control unit (control means)
71 ... Tube pump

Claims (11)

A liquid discharge head that discharges liquid droplets, a first liquid storage unit that stores a liquid to be supplied to the liquid discharge head, and a liquid that is supplied from the first liquid storage unit via a liquid supply path is temporarily held. In the image forming apparatus provided with the second liquid storage means for supplying the liquid to the liquid discharge head,
Detecting means for detecting that the first liquid storage means is mounted;
Sealing means for sealing the nozzle surface of the liquid discharge head;
A discharge path opening / closing means for opening and closing a bubble discharge path for discharging bubbles branched from the liquid supply path;
Pressurizing means for sending liquid from the first liquid storage means to the liquid supply path,
An image forming apparatus comprising: a control unit that controls operations of the sealing unit, the discharge path opening / closing unit, and the pressurizing unit based on a detection result of the detection unit.   2. The image forming apparatus according to claim 1, wherein after the sealing unit seals a nozzle surface of the liquid ejection head based on a detection result of the detection unit, the discharge path opening / closing unit An image forming apparatus, wherein the bubble discharge path is opened, and finally, the pressurizing unit performs control to send liquid from the first liquid storage unit to the liquid supply path.   2. The image forming apparatus according to claim 1, wherein after the sealing unit seals a nozzle surface of the liquid discharge head based on a detection result of the detection unit, the pressurizing unit An image forming apparatus, wherein a liquid is sent from the first liquid storage unit to the liquid supply path, and finally the discharge path opening / closing unit performs control to open the bubble discharge path.   4. The image forming apparatus according to claim 1, wherein the control unit intermittently applies a pressure to the pressurizing unit a plurality of times from the first storage unit to the supply path. 5. An image forming apparatus that performs an operation of feeding out the image.   5. The image forming apparatus according to claim 1, wherein the bubble discharge path is provided at a head position higher than the supply path.   6. The image forming apparatus according to claim 1, wherein the bubble discharge path communicates with a waste liquid storage unit that stores a waste liquid.   7. The image forming apparatus according to claim 1, further comprising a plurality of first liquid storage units that store liquids of different colors, and the liquids of the respective colors simultaneously or selectively from the first liquid storage units of the respective colors. An image forming apparatus comprising pressurizing means for feeding the liquid to a liquid supply path.   8. The image forming apparatus according to claim 1, wherein the discharge path opening / closing means includes an elastically deformable member that forms at least a part of the bubble discharge path, and the elastically deformable member. An image forming apparatus comprising: a compression member that compresses, and the bubble discharge path is closed by pressing the elastically deformable member with the compression member.   9. The image forming apparatus according to claim 1, wherein the sealing unit is a capping unit that seals a nozzle surface of the liquid discharge head outside a printing region.   10. The image forming apparatus according to claim 1, wherein the bubble discharge path includes a bubble capturing unit that captures bubbles. 11.   11. The image forming apparatus according to claim 1, wherein the control unit is configured so that an amount discharged from the bubble discharge path is a discharge port of the bubble discharge path from a connection portion between the first storage unit and the liquid supply path. An image forming apparatus, wherein the pressurizing unit is controlled so as to be substantially the same as the volume of the flow path up to.

Images