JP4882743B2 - Liquid ejection device - Google Patents

Description

  The present invention relates to a liquid ejection apparatus such as an inkjet recording apparatus that records an image on a recording medium by ejecting ink from an ejection head.

  In the conventional ink jet recording apparatus, when the ink viscosity in the nozzle hole of the ejection head rises for a long period of time or when the nozzle hole is clogged due to contamination of impurities, the ink tank that communicates with the ejection head Is known to perform a positive pressure purging operation to restore the function by forcibly ejecting ink from the nozzle holes and forcibly ejecting ink (see, for example, Patent Document 1).

By the way, when a temperature change or the like occurs in the apparatus, an excessive positive pressure or negative pressure may be generated in the ink tank. Then, the pressure propagates from the ink tank to the nozzle hole of the discharge head, and the good meniscus in the nozzle hole is destroyed. Therefore, if a pressure buffer chamber communicating with the air layer in the ink tank is provided to increase the total volume of the air, excessive pressure fluctuations generated in the ink tank can be suppressed, and the meniscus in the nozzle holes can be kept good. Is possible.
Japanese Patent Laid-Open No. 5-92578

  However, if a pressure buffer chamber communicating with the air layer in the ink tank is provided, the positive pressure supplied for the purge is absorbed by the pressure buffer chamber when the positive pressure purge operation described above is performed, and the nozzle hole of the ejection head It is difficult to transmit sufficient positive pressure. Then, in order to perform the positive pressure purge operation appropriately and quickly, it is necessary to use a high pressure pump as a pump for supplying the purge pressure, which leads to an increase in size and cost of the apparatus.

  Therefore, an object of the present invention is to enable a positive pressure purge function to be provided without increasing the size and cost of the apparatus while suppressing pressure fluctuations in the tank due to temperature changes or the like.

  The present invention has been made in view of the above circumstances, and a liquid discharge apparatus according to the present invention includes a liquid storage chamber that communicates with a discharge head and stores liquid supplied to the discharge head, and the liquid A gas circulation chamber having a gas introduction hole for introducing gas, a pressure buffer chamber communicating with the gas circulation chamber via the communication hole, and the gas introduction hole can be opened and closed while communicating with the air layer of the storage chamber An open / close valve and gas introducing means for feeding the liquid in the liquid storage chamber into the discharge head by forcing gas from the gas introduction hole and forcibly discharging the liquid from the discharge head. The valve is configured to be displaceable between a first position that closes the gas introduction hole and opens the communication hole, and a second position that opens the gas introduction hole and closes the communication hole. Have It is characterized in.

  According to the above configuration, when the on-off valve is in the first position, the pressure buffer chamber communicates with the gas flow chamber via the communication hole, and the overall volume of the space communicating with the liquid storage chamber increases. Thus, pressure fluctuation can be suppressed. On the other hand, when the on-off valve is in the second position, the communication hole is closed and the volume of the space communicating with the liquid storage chamber is reduced by the amount corresponding to the pressure buffering chamber. Is pressurized (so-called positive pressure purge operation), the positive pressure is easily transmitted to the ejection head. Therefore, it is not necessary to use a high-pressure pump for the pressurizing pump, and the size and cost of the apparatus can be prevented. Furthermore, since the on-off valve for opening and closing the gas introduction hole also serves as a volume switching function for opening and closing the communication hole, it is not necessary to provide a separate valve for volume switching, and driving of the valve Sources can also be reduced. Therefore, the configuration of the apparatus can be simplified to save space, and the number of parts and the cost can be reduced.

  The gas introduction hole is disposed opposite to the communication hole, the open / close valve is urged in a direction away from the communication hole by an urging means to close the gas introduction hole, and the open / close valve is applied to the urging force. The structure may be such that the communication hole is closed when it is opened against it.

  According to the above-described configuration, since the gas introduction hole and the communication hole are arranged to face each other, the gas introduction hole is opened / closed and the communication hole is closed / opened with a simple structure that only moves the open / close valve. Can be easily performed.

  The on-off valve may be configured to have elasticity such that each of the side facing the gas introduction hole and the side facing the communication hole exhibits a sealing function.

  According to the said structure, a gas introduction hole or a communicating hole can be airtightly obstruct | occluded by the simple structure which only opens and closes an on-off valve.

  The gas introduction hole and the communication hole may be opposed to each other in the vertical direction, and the gas introduction hole and the communication hole may be opened and closed when the on-off valve is displaced up and down.

  According to the said structure, a gas introduction hole or a communicating hole can be airtightly obstruct | occluded by the simple structure which only moves an on-off valve up and down.

  The on-off valve may be configured to open the gas introduction hole by overcoming the urging force of the urging means by the negative pressure generated in the gas circulation chamber when the liquid in the liquid storage chamber is reduced by a predetermined amount or more. Good.

  According to the above configuration, when an excessive negative pressure is generated in the liquid storage chamber, the on-off valve opens to open the gas flow chamber communicating with the liquid storage chamber to the atmosphere, so the on-off valve also serves as the negative pressure control valve. Therefore, the configuration of the apparatus can be further simplified to save space, and the number of parts and cost can be further reduced.

  The pressure buffer chamber may be configured not to include a negative pressure control valve that opens to the atmosphere when the negative pressure in the pressure buffer chamber exceeds a predetermined value.

  According to the above configuration, it is not necessary to separately provide a negative pressure control valve in the pressure buffering chamber, the configuration of the device can be further simplified and space saving can be achieved, and the number of parts and cost can be further reduced. it can.

  The gas introduction means further includes a gas introduction pipe member that introduces gas into the gas introduction hole, and the gas introduction pipe member communicates with the gas circulation chamber in an airtight manner by approaching the gas introduction hole. In addition, the gas introduction hole may be opened by pushing the opening / closing valve at its tip.

  According to the above configuration, since the gas introduction hole is opened by pushing the opening / closing valve at the tip of the gas introduction pipe member, there is no need to separately provide an opening / closing drive source for the opening / closing valve, and the configuration of the apparatus can be further simplified. The number of parts and the cost can be further reduced.

  The pressure buffer chamber may be provided with a positive pressure control valve that opens to the atmosphere when the positive pressure in the pressure buffer chamber exceeds a predetermined value.

  According to the above configuration, even when an excessive positive pressure is generated in the liquid storage chamber due to a temperature change or the like, the on-off valve opens to open the pressure buffer chamber communicating with the liquid storage chamber to the atmosphere. An increase in pressure can be suppressed. Therefore, it is possible to prevent a good meniscus in the nozzle hole of the discharge head communicating with the liquid storage chamber from being destroyed.

  As is clear from the above description, according to the present invention, it is not necessary to use a high-pressure pump for the pressure pump, and the volume switching function for opening and closing the communication hole by the open / close valve of the gas introduction hole is also used. Therefore, the increase in size of the apparatus can be prevented and the number of parts and the cost can be reduced.

  Embodiments according to the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a perspective view showing a multifunction machine 1 having an inkjet recording apparatus 3 (liquid ejection apparatus) according to a first embodiment of the present invention. As shown in FIG. 1, the multifunction device 1 has a printer function, a scanner function, a copy function, and a facsimile function, and has an inkjet recording apparatus 3 for printing at the bottom of the housing 2 and the housing 2. The scanner device 4 is provided on the top of the screen. An opening 5 is formed on the front surface of the housing 2, a paper feed tray 6 of the ink jet recording apparatus 3 is provided below the opening 5, and a paper discharge tray 7 of the ink jet recording apparatus 3 is provided on the upper stage. . An opening / closing lid 8 is provided at the lower right portion of the front side of the inkjet recording apparatus 3, and a main tank mounting portion 9 (see FIG. 3) is provided inside the opening / closing lid 8. An operation panel 10 for operating the inkjet recording device 3, the scanner device 4, and the like is provided on the upper front side of the multifunction device 1. Further, when the multifunction device 1 is connected to an external computer, the multifunction device 1 can operate based on an instruction transmitted from the computer via a driver.

  FIG. 2 is a cross-sectional view schematically illustrating the ink jet recording apparatus 3 of the multifunction machine 1 shown in FIG. As shown in FIG. 2, a paper feed tray 6 is disposed on the bottom side of the multifunction machine 1. On the upper side of the paper feed tray 6, a paper feed driving roller 13 that supplies the uppermost layer of the papers 11 stacked on the paper feed tray 6 to the transport path 12 is provided. The conveyance path 12 makes a U-turn toward the front side after going upward from the back side of the paper feed tray 6, passes through the printing region 14, and is guided to the paper discharge tray 7 (see FIG. 1).

  An image recording unit 15 is provided in the printing area 14. A platen 20 larger than the paper size is disposed below the image recording unit 15. On the upstream side of the image recording unit 15, a conveyance roller 21 and a pinch roller 22 that nipping and conveying the paper 11 flowing through the conveyance path 12 onto the platen 20 are provided. On the downstream side of the image recording unit 15, a paper discharge roller 23 and a pinch roller 24 that sandwich the paper 11 on which image recording has been performed and convey it to the paper discharge tray 7 (see FIG. 1) are provided.

  The image recording unit 15 includes a known piezoelectric-driven ejection head 16 that ejects ink (liquid) from a large number of nozzle holes toward the conveyance path 12, a sub tank 17 that stores ink to be supplied to the ejection head 16, and ejection. A head control board 18 for driving and controlling the head 16 and a carriage 19 for mounting them are provided.

  The sub tank 17 has an ink inflow joint portion 33, and the ink replenishment mechanism 30 is appropriately connected to the ink joint portion 33, whereby the sub tank 17 can be refilled with ink. The ink replenishing mechanism 30 includes a cartridge type main tank 25, an ink supply tube 26 having one end connected to the main tank 25, and an ink outflow joint portion 27 provided at the other end of the ink supply tube 26. Have. The ink outflow joint portion 27 is driven up and down by a driving means (not shown), and the ink outflow joint portion 27 is attached to and detached from the ink inflow joint portion 33 of the sub tank 17.

  FIG. 3 is a plan view of the main part of the ink jet recording apparatus 3 of the multifunction machine 1 shown in FIG. FIG. 4 is a plan view of the main part in the maintenance state of the inkjet recording apparatus 3 of the multifunction machine 1 shown in FIG. As shown in FIG. 3, a pair of flat guide rails 31 and 32 are extended above the platen 20 in the scanning direction orthogonal to the paper transport direction. The guide rails 31 and 32 are provided on substantially the same plane, and their upper surfaces are formed so as to be substantially parallel to the upper surface of the platen 20 and horizontally. The guide rails 31 and 32 support the carriage 19 of the image recording unit 15 so as to be slidable in the extending direction of the guide rails 31 and 32.

  A driving pulley (not shown) and a driven pulley 35 are provided on both ends in the scanning direction on the upper surface of the guide rail 32 on the downstream side in the sheet conveying direction. An annular timing belt 36 is wound between the driving pulley and the driven pulley 35. The carriage 19 is fixed to a part of the timing belt 36 on the bottom surface side. A motor 37 is connected to the shaft of the drive pulley. When the drive pulley is rotated forward and backward by the motor 37, the timing belt 36 moves between the drive pulley and the driven pulley 35. That is, due to the circumferential movement of the timing belt 36, the discharge head 16 (see FIG. 2), the sub tank 17, and the head control board 18 reciprocate together with the carriage 19 on the guide rails 31 and 32. The sub tank 17 has five ink storage chambers corresponding to the five colors of ink used for printing. Further, the sub tank 17 has a volume that can store an amount of ink that is greater than or equal to the amount of ink expected to be consumed in one printing process.

  An ink replenishment mechanism 30 for replenishing ink to the sub tank 17 and a positive pressure purge mechanism 40 (gas introduction means) for maintenance are disposed outside the printing region through which the paper passes. The ink replenishing mechanism 30 is provided on the front side (lower side in FIG. 3) of the guide rail 32 on one end side (right side in FIG. 3) of the carriage 19 in the scanning direction. The ink replenishing mechanism 30 has a main tank 25 that is detachably mounted on the stationary main tank mounting portion 9, and five main tanks 25 are prepared for each ink type.

  As shown in FIGS. 3 and 4, the positive pressure purge mechanism 40 is located on the other end side in the scanning direction of the carriage 19 (on the left side in FIGS. 3 and 4) on the front side of the guide rail 32 (on the lower side in FIGS. 3 and 4). Is provided. The positive pressure purge mechanism 40 discharges ink by empty discharge by supplying compressed air (positive pressure) to the sub tank 17 when the carriage 19 is moved to the left end of the guide rails 31 and 32 during maintenance. The sludge and bubbles accumulated in the head 16 (see FIG. 2) are purged toward a waste ink tank (not shown).

  FIG. 5 is a cross-sectional view taken along the line V-V in FIG. As shown in FIG. 5, the sub tank 17 includes an ink inflow joint portion 33 at a position corresponding to the ink outflow joint portion 27 (see FIG. 2). The ink inflow joint portion 33 communicates with the outside through an inflow port 33a formed in the lower wall, and an inflow valve 34 is inserted so as to be movable up and down. A seal ring 38 is attached around the inlet 33a on the inner surface of the ink inflow joint portion 33. The ink inflow joint portion 33 is provided with a coil spring 39 that urges the inlet valve 34 toward the seal ring 38.

  An ink storage chamber 36 is communicated with the ink inflow joint portion 33 through an ink flow path 42 from above. An outflow hole 36 a is provided in the lower wall of the ink storage chamber 36, and the ink in the ink storage chamber 36 flows from the outflow hole 36 a to the ejection head 16 (see FIG. 2). A communication port 36 c communicating with the upper air layer of the ink storage chamber 36 is formed in a part of the upper wall portion 36 b of the ink storage chamber 36. The subtank 17 is provided with a gas flow chamber 41 adjacent to the left side of the ink inflow joint portion 33 in the drawing (the side opposite to the ink storage chamber 36). A resin film 43 is affixed to the upper surface of the upper wall portion 36b of the ink storage chamber 36, and the gas circulation chamber 41 passes through a labyrinth channel (not shown) between the resin film 43 and the upper wall portion 36b. 36 is in airtight communication. The gas circulation chamber 41 communicates with the outside through a gas introduction hole 41a formed in the lower wall thereof. The gas circulation chamber 41 communicates with the upper pressure buffer chamber 44 through a communication hole 44a formed in the upper wall thereof. The gas introduction hole 41a and the communication hole 44a are vertically opposed to each other.

  An open / close valve 47 is inserted into the gas flow chamber 41 so as to be movable up and down. The on-off valve 47 is inserted into the spring seat 47a, the contact shaft portion 47b that protrudes downward from the spring seat 47a through the gas introduction hole 41a, and the communication hole 44a that protrudes upward from the spring seat 47a. Guide shaft portion 47c. The spring seat portion 47a partially has a clearance between the inner wall surface of the gas circulation chamber 41, and the clearance communicates the upper and lower spaces sandwiching the spring seat portion 47a with a space in the circumferential direction. It is formed as follows. The contact shaft portion 47b has a clearance partially between the inner peripheral surface of the gas introduction hole 41a, and the clearance is located between the upper and lower spaces sandwiching the gas introduction hole 41a in a state of being spaced apart in the circumferential direction. It is formed to communicate. The guide shaft portion 47c has a clearance partially between the inner peripheral surface of the communication hole 44a, and the clearance allows the upper and lower spaces sandwiching the communication hole 44a to communicate with each other while being spaced apart in the circumferential direction. Is formed.

  A seal ring 48 is attached around the gas introduction hole 41 a on the inner surface of the gas flow chamber 41. The on-off valve 47 is provided with a coil spring 46 (biasing means) that urges the spring seat 47 a in a direction away from the communication hole 44 a, and urges the spring seat 47 a so as to be in close contact with the seal ring 48. Thus, the gas introduction hole 41 a is closed by the on-off valve 47. In the present specification, the state where the on-off valve 47 is lowered to the lower limit of the movable range to close the gas introduction hole 41a and the communication hole 44a is opened is called the “first position” of the on-off valve 47.

  Further, an annular seal member 49 is attached to the on-off valve 47 so that the guide shaft portion 47c is fitted on the upper surface of the spring seat portion 47a. Therefore, when the on-off valve 47 moves to the upper limit of its movable range and opens the gas introduction hole 41a, the seal member 49 comes into close contact with the wall surface around the communication hole 44a and the communication hole 44a is closed. Then, the communication between the pressure buffer chamber 44 and the gas circulation chamber 41 is blocked, and the volume of the space communicating with the ink storage chamber 36 is reduced by the amount corresponding to the pressure buffer chamber 44. Thus, the on-off valve 47 serves as a volume switching function.

  Further, even when a negative pressure of a predetermined value or more is generated in the pressure buffer chamber 44, the on-off valve 47 is separated from the seal ring 48 against the coil spring 46, and the gas introduction hole 41a is opened. Then, the gas flow chamber 41 is opened to the atmosphere through the gas introduction hole 41a, and the pressure buffer chamber 44 and the ink storage chamber 36 communicating with the gas flow chamber 41 are opened to the atmosphere. Thus, the on-off valve 44 has a function of a negative pressure control valve in addition to the volume switching function.

  The lower wall of the pressure buffer chamber 44 is formed with a first atmosphere opening hole 44b communicating with the valve chamber 45 adjacent to the gas circulation chamber 41, and the valve chamber 45 opens and closes the first atmosphere opening hole 44b. A positive pressure control valve 50 is provided. The positive pressure control valve 50 includes a spring seat portion 50a and a shaft portion 50b that protrudes upward from the spring seat portion 50a and is inserted into the first atmosphere opening hole 44b. The spring seat portion 50a has a clearance partially between the inner peripheral surface of the valve chamber 45, and the clearance communicates with the upper and lower spaces sandwiching the spring seat portion 50a. The shaft portion 50b has a clearance partially between the inner peripheral surface of the first atmosphere opening hole 44b, and the clearance communicates with the upper and lower spaces sandwiching the first atmosphere opening hole 44b.

  A seal ring 51 is attached around the first atmosphere opening hole 44 b on the inner surface of the valve chamber 45. The positive pressure control valve 50 is provided with a coil spring 52 that urges the spring seat portion 50 a toward the seal ring 51. A second atmosphere opening hole 45 a is formed in the lower wall of the valve chamber 45. Therefore, when a positive pressure of a predetermined value or more is generated in the pressure buffer chamber 44, the positive pressure control valve 50 separates from the seal ring 51 against the coil spring 52, and the first atmosphere opening hole 44b is opened. Then, the first atmosphere opening hole 44b communicates with the second atmosphere opening hole 45a, the pressure buffer chamber 44 is opened to the atmosphere, and the gas circulation chamber 41 and the ink storage chamber 36 communicating therewith are opened to the atmosphere. The pressure buffer chamber 44 itself is not provided with a negative pressure control valve that opens to the atmosphere when the negative pressure in the pressure buffer chamber 44 exceeds a predetermined value.

  A positive pressure purge mechanism 40 (gas introduction means) is arranged below the on-off valve 47. The positive pressure purge mechanism 40 includes a pressurizing pump 60 that supplies compressed air, a flexible tube 61 that extracts compressed air from the pressurizing pump 60, and a gas introduction pipe member that is connected to the tip of the flexible tube 61. 62, an eccentric cam 66 that contacts the gas introduction pipe member 62 from below, a motor 64 that rotationally drives the eccentric cam 66, and a guide body 63 that is stationary so as to guide the gas introduction pipe member 62 so as to be slidable up and down. It has.

  The gas introduction pipe member 62 includes a pipe portion 62 a that forms the internal flow path 67, a lower end connection portion 62 b that communicates with the internal flow path 67 and protrudes downward to be connected to the flexible tube 61, and a pipe portion 62 a A tip 62c that is an upper portion facing the on-off valve 47, a guided portion 62d that protrudes laterally so as to slidably contact the inner surface of the guide body 63, and a driven portion that is pushed by the eccentric cam 66 from below. 62e. The distal end portion 62 c of the gas introduction pipe member 62 is located below the contact shaft portion 47 b of the on-off valve 47. An annular seal member 68 is externally fitted to the distal end portion 62 c of the gas introduction pipe member 62. The seal member 68 protrudes upward from the tip end portion 62 c and can be in close contact with the lower surface of the gas circulation chamber 41 so as to surround the gas introduction hole 41 a when the gas introduction pipe member 62 is raised.

  6 is a cross-sectional view in which the on-off valve 47 is in the “second position” in the same cross section as FIG. As shown in FIG. 6, when the drive shaft 65 of the motor 64 rotates, a disc-shaped eccentric cam 66 attached eccentrically with respect to the drive shaft 65 pushes up the driven portion 62 e of the gas introduction pipe member 62. Then, the gas introduction pipe member 62 rises along the guide body 63, the seal member 68 comes into close contact with the periphery of the gas introduction hole 41a on the lower surface of the gas circulation chamber 41, and the abutment shaft of the on-off valve 47 at the distal end portion 62c. The portion 47b is pushed upward to open the gas introduction hole 41a. Then, the internal flow path 67 of the gas introduction pipe member 62 is hermetically communicated with the gas flow chamber 41 through the gas introduction hole 41a.

  When the on-off valve 47 moves to the upper limit of the movable range, the seal member 49 of the on-off valve 47 comes into close contact with the wall surface around the communication hole 44a and the communication hole 44a is closed. Then, the communication between the pressure buffer chamber 44 and the gas circulation chamber 41 is blocked, and the volume of the space communicating with the ink storage chamber 36 is reduced by the amount corresponding to the pressure buffer chamber 44. In the specification of the present application, the state in which the on-off valve 47 is raised to the upper limit of the movable range, the gas introduction hole 41a is opened, and the communication hole 44a is closed is called the “second position” of the on-off valve 47.

  In this “second position”, if the pressurized pump 60 is operated to introduce compressed air from the gas introduction pipe member 62 into the gas flow chamber 41 through the gas introduction hole 41a, the positive pressure by the compressed air is increased. The ink is transmitted to the ink storage chamber 36 without being transmitted to the buffer chamber 44, and the ink in the ink storage chamber 36 is forcibly sent to the ejection head 16 (see FIG. 2) from the outlet 36a. Then, ink is forcibly ejected from the nozzle holes (not shown) of the ejection head 16, and the ink whose viscosity has increased due to drying, impurities that clog the nozzle holes, and the like are discharged to the outside (positive pressure purge operation).

  According to the above configuration, when the on-off valve 47 is set to the “first position”, the entire volume of the space in which the pressure buffer chamber 44 communicates with the gas circulation chamber 41 through the communication hole 44 a and communicates with the ink storage chamber 36. Therefore, even if the pressure in the ink storage chamber 36 fluctuates due to a change in temperature, a change in the remaining amount of ink, or the like, the pressure fluctuation in the ink storage chamber 36 can be absorbed by the pressure buffer chamber 44. On the other hand, when the on-off valve 47 is set to the “second position”, the communication hole 44a is closed and the volume of the space communicating with the ink storage chamber 36 is reduced by the amount corresponding to the pressure buffer chamber 44. When air is introduced to pressurize the ink storage chamber 36, the positive pressure is easily transmitted to the ejection head 16 (see FIG. 2). Therefore, it is not necessary to use a high-pressure pump 60 for the pressurizing pump 60, and the size and cost of the apparatus can be prevented.

  Further, the on-off valve 47 for opening and closing the gas introduction hole 41a also serves as a volume switching function for opening and closing the communication hole 44a. In other words, the positive pressure purge opening / closing valve 47 also serves as a volume switching valve. Therefore, it is not necessary to separately provide a volume switching dedicated valve, and the drive source of the volume switching dedicated valve can be reduced.

  The on-off valve 47 opens the gas introduction hole 41a by overcoming the urging force of the coil spring 46 due to the negative pressure generated in the gas circulation chamber 41 when the ink in the ink storage chamber 36 is reduced by a predetermined amount or more, and opens the ink introduction chamber 41a. 36 is opened to the atmosphere. That is, the positive pressure purge on-off valve 47 not only serves as a volume switching valve, but also serves as a negative pressure control valve. This eliminates the need to provide a negative pressure control valve in the pressure buffer chamber 44 itself.

  Furthermore, since the on-off valve 47 is pushed up directly by the tip end portion 62c of the gas introduction pipe member 62 to open the gas introduction hole 41a, it is not necessary to separately provide an on-off drive source for the on-off valve 47, and the configuration of the apparatus is simplified. In addition, the number of parts and the cost can be reduced. In the embodiment, the seal ring 48 is attached to the inner surface of the gas circulation chamber 41, but may be attached to the lower surface of the spring seat 47 a of the on-off valve 47. Further, the seal member 49 is attached to the upper surface of the spring seat 47a of the on-off valve 47, but may be attached to the communication hole 44a side.

(Second Embodiment)
Next, a second embodiment will be described. FIG. 7 is a cross-sectional view of the on-off valve 147 according to the second embodiment of the present invention in the “first position”. The difference from the first embodiment is that the seal member 149 that closes the communication hole 44a is different. In addition, the same code | symbol is suitably attached | subjected to the structure similar to 1st Embodiment, and description is abbreviate | omitted. As shown in FIG. 7, the ink storage chamber 136 of the sub-tank 117 of this embodiment has a communication port 136c in a part of its upper wall portion 136b. A serpentine labyrinth channel 136d in a plan view is recessed in the upper surface of the upper wall 136b. One end of the labyrinth channel 136d communicates with the communication port 136c and the other end communicates with the gas flow chamber 41. Communicate.

  An open / close valve 147 is inserted into the gas flow chamber 41 so as to be movable up and down. The on-off valve 147 includes a spring seat portion 147a and a contact shaft portion 147b that protrudes downward from the spring seat portion 147a through the gas introduction hole 41a and faces the communication hole 44a of the spring seat portion 147a. A seal member 149 is attached to the upper surface. The seal member 149 has an area capable of closing the communication hole 44a and the periphery thereof in plan view. The seal member 149 has a higher sealing pressure than the seal ring 48 for sealing the gas introduction hole 41a. For example, the seal ring 48 has a seal pressure with a negative pressure of about 2 KPa, while the seal member 149 has a seal pressure with a positive pressure of 60 KPa or more.

  An opening 144c is formed in the upper wall of the pressure buffer chamber 144, and the resin film 143 is attached to the entire upper surface of the sub tank 117, whereby the communication port 136c and the labyrinth flow path 136d are closed and the opening 144c is closed. Is closed.

  FIG. 8 is a cross-sectional view in which the on-off valve 147 is in the “second position” in the same cross section as FIG. 7. As shown in FIG. 8, when the gas introduction pipe 62 is driven to rise, the seal member 68 comes into close contact with the periphery of the gas introduction hole 41a on the lower surface of the gas circulation chamber 41, and the on-off valve 147 contacts the tip 62d. The shaft portion 147b is pushed upward to open the gas introduction hole 41a. Then, the internal flow path 67 of the gas introduction pipe 62 is hermetically communicated with the gas circulation chamber 41 via the gas introduction hole 41a, and the seal member 149 of the on-off valve 147 is in close contact with the communication hole 44a and its surroundings, and the communication hole. 44a is tightly closed. Then, the communication between the pressure buffer chamber 144 and the gas flow chamber 41 is blocked, and the volume of the space communicating with the ink storage chamber 36 is reduced by the amount of the pressure buffer chamber 44.

  With the above configuration, the seal member 149 that performs sealing at the time of positive pressure purge that supplies compressed air to the gas circulation chamber 41 has a higher seal pressure resistance than the seal ring 48 that performs sealing at normal time. It can be performed stably. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

(Third embodiment)
FIG. 9 is a cross-sectional view of the on / off valve 147 according to the third embodiment of the present invention in the “first position”. FIG. 10 is a cross-sectional view in which the on-off valve 147 is in the “second position” in the same cross section as FIG. 9. The difference from the first embodiment is that a negative pressure control valve 270 is provided in the pressure buffer chamber 244. In addition, the same code | symbol is suitably attached | subjected to the structure similar to 1st and 2nd embodiment, and description is abbreviate | omitted. As shown in FIGS. 9 and 10, a third atmosphere opening hole 244 c is formed in the upper wall of the pressure buffer chamber 244. A negative pressure control valve 270 is provided in the pressure buffer chamber 244 so as to reciprocate so as to open and close the third atmosphere opening hole 244c. The negative pressure control valve 270 has a spring seat portion 270a and a shaft portion 270b that protrudes upward from the spring seat portion 270a and passes through the third atmosphere opening hole 244b. The shaft portion 270b has a clearance partially between the inner peripheral surface of the third atmosphere opening hole 244c, and this clearance communicates with the upper and lower spaces sandwiching the third atmosphere opening hole 244c.

  A seal ring 271 is attached to the inner surface of the pressure buffer chamber 244 around the third atmosphere opening hole 244c. The negative pressure control valve 270 is provided with a coil spring 272 that biases the spring seat 270a toward the seal ring 271. Therefore, when a negative pressure of a predetermined value or more is generated in the ink storage chamber 136, the negative pressure is transmitted to the pressure buffer chamber 244, and the negative pressure control valve 270 is separated from the seal ring 271 against the coil spring 272. The third atmosphere opening hole 244c is opened. Then, the gas circulation chamber 41 and the ink storage chamber 136 communicating with the pressure buffer chamber 244 are opened to the atmosphere. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

  Each of the above-described embodiments is an application of the present invention to an ink jet recording apparatus, but may be applied to an apparatus that discharges a liquid other than ink. In each of the embodiments described above, the pressure buffer chamber, the gas circulation chamber, and the like are formed integrally with the ink storage chamber to form the sub tank. However, the pressure buffer chamber, the gas circulation chamber, and the like are separate from the ink storage chamber. It may be formed of a body.

  As described above, the liquid ejection apparatus according to the present invention has an excellent effect of simplifying the apparatus, saving space, and reducing the number of parts, and an ink jet recording apparatus that can exhibit the significance of this effect. Can be widely applied to.

1 is a perspective view showing a multifunction machine having an inkjet recording apparatus (liquid ejection apparatus) according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view schematically illustrating the inkjet recording apparatus of the multifunction machine illustrated in FIG. 1. FIG. 2 is a plan view of a main part in an ink replenishment state of the inkjet recording apparatus of the multifunction peripheral shown in FIG. 1. FIG. 2 is a plan view of a main part in a maintenance state of the inkjet recording apparatus of the multifunction machine shown in FIG. 1. FIG. 5 is a cross-sectional view taken along the line V-V in FIG. FIG. 6 is a cross-sectional view in which the on-off valve is in a “second position” in the same cross section as FIG. 5. It is sectional drawing in which the on-off valve of 2nd Embodiment of this invention is in "1st position." FIG. 8 is a cross-sectional view in which the on-off valve is in a “second position” in the same cross section as FIG. 7. It is sectional drawing in which the on-off valve of 3rd Embodiment of this invention exists in a "1st position." FIG. 10 is a cross-sectional view in which the on-off valve is in a “second position” in the same cross section as FIG. 9.

Explanation of symbols

1 MFP 3 Inkjet recording device (liquid ejection device)
16 Discharge head 17 Sub tank 36 Ink storage chamber (liquid storage chamber)
40 Positive pressure purge mechanism (gas introduction means)
41 Gas distribution chamber 41a Gas introduction hole 44 Pressure buffer chamber 44a Communication hole 47 On-off valve 48 Seal ring 49 Seal member 50 Positive pressure control valve 62 Gas introduction pipe 62d Tip

Claims (8)

A liquid storage chamber that communicates with the discharge head and stores liquid supplied to the discharge head;
A gas flow chamber having a gas introduction hole for introducing gas while communicating with the air layer of the liquid storage chamber;
A pressure buffer chamber communicating with the gas flow chamber through a communication hole;
An on-off valve capable of opening and closing the gas introduction hole;
Gas introduction means for sending the liquid in the liquid storage chamber to the ejection head by introducing gas from the gas introduction hole, and forcibly ejecting the liquid from the ejection head;
The on-off valve is displaceable between a first position that closes the gas introduction hole and opens the communication hole, and a second position that opens the gas introduction hole and closes the communication hole. A liquid ejecting apparatus characterized by being configured. The gas introduction hole is disposed opposite to the communication hole, and the on-off valve is urged by an urging means in a direction away from the communication hole to close the gas introduction hole,
The liquid ejection device according to claim 1, wherein the communication hole is closed when the on-off valve is opened against the urging force.   3. The liquid ejection apparatus according to claim 1, wherein the on-off valve is configured to have elasticity so that each of a side facing the gas introduction hole and a side facing the communication hole exhibits a sealing function.   4. The liquid according to claim 3, wherein the gas introduction hole and the communication hole are vertically opposed to each other, and the gas introduction hole and the communication hole are opened and closed when the on-off valve is displaced up and down. Discharge device.   The on-off valve is configured to open the gas introduction hole by overcoming an urging force of the urging means by a negative pressure generated in the gas circulation chamber when the liquid in the liquid storage chamber decreases by a predetermined amount or more. The liquid ejection device according to 2 or 3.   6. The liquid ejection apparatus according to claim 5, wherein the pressure buffer chamber is not provided with a negative pressure control valve that opens to the atmosphere when the negative pressure in the pressure buffer chamber exceeds a predetermined value. The gas introduction means further includes a gas introduction pipe member for introducing gas into the gas introduction hole,
The gas introduction pipe member is configured to airtightly communicate with the gas circulation chamber by approaching the gas introduction hole and push the opening / closing valve at a tip portion thereof to open the gas introduction hole. The liquid discharge apparatus according to claim 1.   The liquid ejection device according to claim 1, wherein the pressure buffering chamber is provided with a positive pressure control valve that opens to the atmosphere when the positive pressure in the pressure buffering chamber exceeds a predetermined value.

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