Liquid ejection device

Abstract

The present application provides a liquid ejection device capable of recovering a pressure drop in a storage portion accompanying discharge of liquid from a nozzle without increasing the size of the device. A controller of a multifunction peripheral counts a count value indicating an amount of ink discharged from a nozzle of a head while a valve unit provided in a storage portion of the ink is in a closed state, and makes the valve unit into an open state on condition that the count value reaches an open threshold ΔV. When a volume of the storage portion is set to Vtmax, a maximum amount of ink that can be stored in the storage portion is set to Vi, atmospheric pressure is set to P, and a meniscus pressure of the ink formed at the nozzle is set to Pm, the open threshold ΔV satisfies ΔV ≤ (Vtmax - Vi) × Pm / (P - Pm).

Description

TECHNICAL FIELD

[0001] The present application relates to a liquid ejecting apparatus having a head which ejects a liquid supplied from a reservoir. BACKGROUND

[0002] As an apparatus which ejects ink stored in a tank from a nozzle to perform image recording, an ink jet pen is known (see Patent Document 1). In the ink jet pen, a liquid surface of ink stored in an ink cartridge is located at a position higher than an opening of the nozzle. In the ink cartridge, a gas layer is not communicated with the outside, or a valve is provided on a gas flow path which communicates the gas layer with the outside.

[0003] PRIOR ART DOCUMENT

[0004] PATENT DOCUMENT

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 55-65560 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] If the gas layer of the ink cartridge is not communicated with the outside, as ink is consumed, the pressure of the gas layer decreases, and as a result, the meniscus formed at the opening of the nozzle can be broken. The smaller the volume of the gas layer, the more easily the pressure of the gas layer of the ink cartridge decreases. However, if the volume of the gas layer is increased in the ink cartridge, the ink cartridge becomes large, and as a result, the apparatus becomes large.

[0008] The present application has been achieved in view of the above-described circumstances, and has an object to provide a structure which recovers a decrease in pressure in a reservoir accompanying discharge of a liquid from a nozzle without making an apparatus large.

[0009] TECHNICAL SOLUTION FOR SOLVING THE PROBLEMS

[0010] (1) A liquid ejecting apparatus according to the present application includes: a head having a nozzle which ejects a liquid; a reservoir in which the liquid is stored with a liquid surface, the reservoir being capable of storing a maximum amount of the liquid at a height which is higher than an opening of the nozzle; a gas flow path which communicates a gas layer of the reservoir with the outside through an atmosphere opening which is open to the outside; a valve unit which opens or closes the atmosphere opening or the gas flow path; a memory; and a controller. The memory stores an opening threshold AV, and the controller counts a count value which indicates an amount of the liquid discharged from the nozzle in a closed state in which the valve unit closes the atmosphere opening or the gas flow path, and causes the valve unit to be in an open state in which the atmosphere opening or the gas flow path is opened, on condition that the count value reaches the opening threshold AV, the opening threshold AV satisfying the following equation (1),

[0011] ΔV ≤ (Vtmax - Vi) x Pm / (P - Pm)...(1)

[0012] wherein Vtmax is the volume of the storage section, Vi is the maximum amount of liquid that can be stored in the storage section, P is the atmospheric pressure, and Pm is the meniscus pressure of the liquid formed in the nozzle.

[0013] According to the liquid ejection apparatus described above, the volume of the storage section can be reduced, and the pressure of the gas in the storage section is made to be the atmospheric pressure at an appropriate timing, so the liquid can be stably ejected from the nozzle.

[0014] (2) Preferably, the controller resets the count value to an initial value after making the valve unit to be in the open state.

[0015] According to this structure, the valve unit can be made to be in the open state every time the count value reaches the open threshold ΔV.

[0016] (3) Preferably, the controller acquires the remaining amount of the liquid stored in the storage section after resetting the count value to the initial value, and changes the open threshold ΔV according to the acquired remaining amount.

[0017] According to this structure, the open threshold ΔV that is appropriate for the remaining amount of the storage section is set.

[0018] (4) Preferably, the controller makes the valve unit to be in the open state on the condition that the liquid is not discharged from the nozzle.

[0019] (5) Preferably, Vtmax is 25 mL or less, Vi is 4.2 mL or less, and the open threshold ΔV is 0.53 mL or less.

[0020] (6) Preferably, Vtmax is 25 mL or less, Vi is 12.5 mL or less, and the open threshold ΔV is 0.32 mL or less.

[0021] (7) Preferably, the open threshold ΔV is 0.16 mL or more.

[0022] Effects of the Invention

[0023] According to the present application, the pressure decrease in the storage section accompanying the discharge of the liquid from the nozzle can be recovered without making the apparatus large. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a perspective view of a multifunction peripheral 10 as an example of an embodiment of the present application.

[0025] Figure 2is a longitudinal sectional view schematically showing the internal structure of the printing section 11.

[0026] Figure 3 is a sectional view showing the section of the recording section 24 after being cut with a plane orthogonal to the front-rear direction 8.

[0027] Figure 4 is a functional block diagram showing the multifunction peripheral 10.

[0028] Figure 5 is a diagram for explaining the operation of the valve unit 91, Figure 5 A in FIG. 6 is a diagram showing the valve unit 91 in a closed state, Figure 5 B in FIG. 6 is a diagram showing the valve unit 91 in an open state.

[0029] Figure 6 is a flowchart for explaining the image recording control and the pressure release control by the controller 130.

[0030] Figure 7 is a diagram schematically showing the state of the gas layer of the storage section 80, Figure 7 A in FIG. 7 is a diagram showing the state before image recording, Figure 7 B in FIG. 7 is a diagram showing the state after image recording.

[0031] Figure 8 is a diagram showing the range of the open threshold value AV and the volume Vtmax of the storage section 80, Figure 8 A in FIG. 8 is a diagram showing the range in the case where the amount of the ink 99 is set to 4.2 mL, Figure 8 B in FIG. 8 is a diagram showing the range in the case where the amount of the ink 99 is set to 12.5 mL.

[0032] Figure 9 is a longitudinal sectional view showing the section of the storage section 80 of the deformation example, cut with a plane orthogonal to the front-rear direction 8.

[0033] Figure 10 is a longitudinal sectional view showing the section of the storage section 80 of the other deformation example, cut with a plane orthogonal to the front-rear direction 8. DETAILED DESCRIPTION

[0034] Hereinafter, an embodiment of the present application will be described. Furthermore, the embodiment described below is only one example of the present application, and it is needless to say that the embodiment of the present application can be appropriately changed within a range not changing the gist of the present application. In addition, in the following description, the progress from the start point of an arrow toward the end point is expressed as a direction, and the to-and-fro on the line connecting the start point and the end point of the arrow is expressed as a direction. In addition, in the following description, the state in which the multifunction peripheral 10 is set to be usable (the state in which the multifunction peripheral 10 is set to be usable is the state in which the multifunction peripheral 10 is set to be usable in the following description) Figure 1The up-and-down direction 7 is defined with the state of the paper sheet 12 as a reference, the front-and-back direction 8 is defined with the surface provided with the opening 13 as a front surface 23, and the left-and-right direction 9 is defined with the complex machine 10 viewed from the front. The up-and-down direction 7, the front-and-back direction 8, and the left-and-right direction 9 are orthogonal to each other.

[0035] [Overall structure of the complex machine 10]

[0036] As shown in Figure 1 , the complex machine 10 (an example of a liquid discharge apparatus) has a substantially rectangular parallelepiped-shaped casing 14. A printing section 11 is provided at a lower portion of the casing 14. The complex machine 10 has various functions such as a facsimile function and a printing function. As the printing function, the complex machine 10 has a function of performing image recording on one surface of a paper sheet 12 (refer to Figure 2 ) in an inkjet manner. In addition, the complex machine 10 can also perform image recording on both surfaces of the paper sheet 12. An operation section 17 is provided at an upper portion of the casing 14. The operation section 17 is configured of buttons operated for instructions for image recording, various settings, a liquid crystal display that displays various information, and the like. In the present embodiment, the operation section 17 is configured of a touch panel having both functions of the buttons and the liquid crystal display.

[0037] As shown in Figure 2 , the printing section 11 is provided with a supply tray 20, a supply section 16, an outer guide member 18, an inner guide member 19, a pair of convey rollers 59, a pair of discharge rollers 44, a platen 42, a recording section 24, an encoder 35 (refer to Figure 4 ), a rotary encoder 75 (refer to Figure 4 ), a controller 130 (refer to Figure 4 ), and a memory 140 (refer to Figure 4 ). These components are arranged in the inside of the casing 14. Various state sensors (not shown) that detect the state of the complex machine 10 and output a signal corresponding to the detection result are arranged in the inside of the casing 14.

[0038] [Supply tray 20]

[0039] As shown in Figure 1 , the opening 13 is formed in the front surface 23 of the printing section 11. The supply tray 20 is capable of being inserted and withdrawn with respect to the casing 14 via the opening 13 by moving in the front-and-back direction 8. The supply tray 20 is capable of moving between a supply position (a position shown in Figure 1 and Figure 2 ) in which the supply tray 20 is attached to the casing 14 and a non-supply position in which the supply tray 20 is withdrawn from the casing 14. The supply tray 20 moves to the supply position by being inserted in the rearward direction with respect to the casing 14, and moves to the non-supply position by being pulled in the forward direction with respect to the casing 14.

[0040] The supply tray 20 is a box-shaped component that is open at the top and houses the paper sheet 12. As shown inFigure 2 As shown, the paper sheet 12 is supported in a superposed state on the bottom plate 22 of the feeding tray 20. The discharge tray 21 is disposed above the front portion of the feeding tray 20. The paper sheet 12 on which the image recording by the recording section 24 is performed and discharged is supported on the upper surface of the discharge tray 21. When the feeding tray 20 is in the feeding position, the paper sheet 12 supported on the feeding tray 20 can be fed to the conveyance path 65.

[0041] [Feeding section 16]

[0042] As shown, the feeding section 16 is disposed below the recording section 24 and above the bottom plate 22 of the feeding tray 20. The feeding section 16 has a feeding roller 25, a feeding arm 26, a drive transmission mechanism 27, and a shaft 28. The feeding roller 25 is rotatably supported at the front end portion of the feeding arm 26. The feeding arm 26 is turned about the shaft 28 provided at the base end portion in the direction of the arrow 29. Thus, the feeding roller 25 can be brought into abutment with and separated from the paper sheet 12 supported on the feeding tray 20 or the paper sheet 12 supported on the feeding tray 20. Figure 2

[0043] The feeding roller 25 is rotated by the drive transmission mechanism 27 formed by a plurality of gears engaged with each other, by the driving force of the feeding motor 102 (see FIG. 2) transmitted thereto. Thus, the uppermost paper sheet 12 of the paper sheets 12 supported on the bottom plate 22 of the feeding tray 20 in the feeding position, which is in abutment with the feeding roller 25, is fed to the conveyance path 65. Note that the drive transmission mechanism 27 is not limited to the plurality of gears engaged with each other, and may, for example, be a belt stretched over the shaft 28 and the shaft of the feeding roller 25. Figure 4

[0044] [Conveyance path 65]

[0045] As shown, the conveyance path 65 extends from the rear end portion of the feeding tray 20. The conveyance path 65 has a curved portion 33 and a straight portion 34. The curved portion 33 extends in a U-shape turning upward and from the rear to the front. The straight portion 34 extends substantially in the front-rear direction 8. Figure 2

[0046] The curved portion 33 is formed by the outer guide member 18 and the inner guide member 19 opposed to each other with a prescribed interval therebetween. The outer guide member 18 and the inner guide member 19 extend in the left-right direction 9. The straight portion 34 is formed by the recording section 24 and the platen 42 opposed to each other with a prescribed interval therebetween at the position where the recording section 24 is disposed.

[0047] ​​​Paper 12, supported on the feed tray 20, is conveyed by the feed roller 25 at the bend 33 and reaches the conveyor roller pair 59. The paper 12, held by the conveyor roller pair 59, is conveyed forward toward the recording unit 24 at the straight section 34. The paper 12, reaching directly below the recording unit 24, is image-recorded by the recording unit 24. The image-recorded paper 12 is then conveyed forward at the straight section 34 and discharged onto the discharge tray 21. Thus, the paper 12 moves along... Figure 2 The conveying direction 15, indicated by the arrow with a single dotted line, is conveyed.

[0048] [Conveyor roller pair 59 and discharge roller pair 44]

[0049] like Figure 2 As shown, a pair of conveying rollers 59 is arranged in the straight section 34. A pair of discharge rollers 44 is arranged in the straight section 34 downstream of the pair of conveying rollers 59 in the conveying direction 15.

[0050] The conveyor roller pair 59 includes a conveyor roller 60 and a pinch roller 61 disposed below and opposite the conveyor roller 60. The pinch roller 61 is pressed against the conveyor roller 60 by an elastic component (not shown) such as a helical spring. The conveyor roller pair 59 is capable of holding paper 12.

[0051] The discharge roller pair 44 includes a discharge roller 62 and a toothed roller 63 disposed above and opposite the discharge roller 62. The toothed roller 63 is pressed toward the discharge roller 62 by an elastic member such as a helical spring (not shown). The discharge roller pair 44 is capable of holding paper 12.

[0052] The conveyor roller 60 and the discharge roller 62 are driven by the conveying motor 101 (see reference). Figure 4 The paper 12 is rotated by a driving force. When the conveyor roller 60 rotates while the paper 12 is held by the conveyor roller pair 59, the paper 12 is conveyed in the conveying direction 15 by the conveyor roller pair 59 and is conveyed onto the printing plate 42. When the discharge roller 62 rotates while the paper 12 is held by the discharge roller pair 44, the paper 12 is conveyed in the conveying direction 15 by the discharge roller pair 44 and is discharged onto the discharge tray 21. Furthermore, a common motor can be used as the conveying motor 101 and the feeding motor 102. In this case, the drive transmission path from the common motor to each roller can be switched.

[0053] Furthermore, the components for conveying the paper 12 are not limited to the roller pairs described above. For example, a conveyor belt can be configured instead of the conveyor roller pair 59 and the discharge roller pair 44.

[0054] [Imprint Plate 42]

[0055] like Figure 2As shown, the platen 42 is disposed in the straight portion 34 of the conveyance path 65. The platen 42 is opposed to the recording portion 24 in the up-down direction 7. The platen 42 supports the paper sheet 12 conveyed by the conveyance path 65 from below. The paper sheet 12 conveyed by the conveyance path 65 passes through a region (hereinafter, referred to as a medium passing region) between the right end and the left end of the platen 42 in the left-right direction 9.

[0056] [Recording portion 24]

[0057] As shown, the recording portion 24 is disposed in opposition to the platen 42 above the platen 42. The recording portion 24 is provided with a carriage 40, a head 38, and a storage portion 80. Figure 2

[0058] The carriage 40 is supported by two guide rails 56, 57 disposed at intervals in the front-rear direction 8 so as to be movable in the left-right direction 9 orthogonal to the conveyance direction 15. The carriage 40 is movable in the left-right direction 9 from the right of the medium passing region to the left of the medium passing region. Further, the moving direction of the carriage 40 is not limited to the left-right direction 9, but can be a direction crossing the conveyance direction 15.

[0059] The guide rail 56 is disposed upstream of the head 38 in the conveyance direction 15. The guide rail 57 is disposed downstream of the head 38 in the conveyance direction 15. The guide rails 56, 57 are supported by a pair of side frames (not shown) disposed outside the straight portion 34 of the conveyance path 65 in the left-right direction 9. The carriage 40 is moved by a driving force applied from a carriage drive motor 103 (refer to Figure 4 ).

[0060] An encoder 35 (refer to Figure 4 ) is disposed in the guide rail 56 or the guide rail 57. The encoder 35 is provided with an encoder belt extending in the left-right direction 9 and an optical sensor provided at a portion of the carriage 40 opposed to the encoder belt. A pattern in which light-transmitting portions and light-blocking portions are alternately disposed at equal intervals in the left-right direction 9 is recorded on the encoder belt. A pulse signal is detected by detecting the light-transmitting portions and the light-blocking portions by the optical sensor. The pulse signal is a signal corresponding to the position of the carriage 40 in the left-right direction 9. The pulse signal is output to a controller 130 (refer to Figure 4 ).

[0061] The head 38 is supported by the carriage 40. A lower surface 68 of the head 38 is exposed downward and opposes the platen 42. The head 38 is provided with a plurality of nozzles 39, an ink flow path 37, and a piezoelectric element 45 (refer to Figure 4 ).

[0062] The plurality of nozzles 39 are opened in the lower surface 68 of the head 38. The ink flow path 37 connects the storage portion 80 and the plurality of nozzles 39. The piezoelectric element 45 (refer to Figure 4 ​) ink droplets from the nozzles 39 downward by deforming a portion of the ink flow path 37. The piezoelectric element 45 is actuated by being supplied with electric power from the controller 130 (refer to Figure 4 ). In this way, the head 38 has the nozzles 39 that eject ink (an example of a liquid).

[0063] The storage portion 80 is supported to the carriage 40 in a state of being mounted to the carriage 40. The storage portion 80 has an internal space 81. In the internal space 81, the ink 99 is stored. In the present embodiment, the recording portion 24 is provided with one storage portion 80. In the one storage portion 80, the ink 99 of black color is stored. In addition, the color of the ink 99 stored in the storage portion 80 is not limited to black.

[0064] The storage portion 80 is located at a position higher than the head 38. In addition, in the present embodiment, the entire storage portion 80 is located at a position higher than the head 38, but it can be that a part of the storage portion 80 is located at a position higher than the head 38 and the other part of the storage portion 80 is located at a position lower than the head 38. The internal space 81 of the storage portion 80 communicates with the plurality of nozzles 39 via the ink flow path 37. Thereby, the ink 99 is supplied from the internal space 81 to the nozzles 39.

[0065] An injection port 83 for injecting the ink 99 into the internal space 81 is provided in an upper wall 82 of the storage portion 80. The injection port 83 penetrates the upper wall 82 in the thickness direction, and communicates the internal space 81 with the outside of the storage portion 80. A protruding wall 84 (refer to Figure 3 ) is provided around the injection port 83 on the upper surface of the upper wall 82. The injection port 83 is closed by fitting the lid 85 to the protruding wall 84. When the lid 85 is detached from the protruding wall 84, the injection port 83 is exposed to the outside. In this state, a bottle (not shown) is inserted into the injection port 83, and the ink 99 is injected from the bottle into the internal space 81 via the injection port 83. In addition, the injection port 83 can be provided at a position other than the upper wall 82 as long as it communicates the upper portion of the internal space 81 with the outside.

[0066] As shown in Figure 3 , an atmosphere opening 88 that opens to the outside of the storage portion 80 is provided in an upper side portion of a side wall 87 of the storage portion 80. Air enters a portion of the internal space 81 of the storage portion 80 in which the ink 99 is not present. The portion of the internal space 81 of the storage portion 80 in which air enters is referred to as a gas layer. A gas flow path 89 is formed between the gas layer of the storage portion 80 and the outside via the atmosphere opening 88. The gas flow path 89 communicates the gas layer of the storage portion 80 with the outside through the atmosphere opening 88 that opens to the outside.

[0067] A valve unit 91 is provided in the storage section 80 to open or close the atmospheric vent 88. The valve unit 91 includes a valve 92 and a coil spring 93. The valve 92 is a component that abuts against or separates from the atmospheric vent 88. The coil spring 93 is a component that applies force to the right to make the valve 92 abut against the atmospheric vent 88. A side surface 86 is formed in the storage section 80 opposite to the coil spring 93, facing the side wall 87. The left end of the coil spring 93 is connected to the side surface 86, and the right end is connected to the valve 92.

[0068] [Rotary Encoder 75]

[0069] Figure 4 The rotary encoder 75 shown is mounted on the conveyor motor 101 (see reference). Figure 4 The encoder disk, which rotates along the shaft of the conveyor motor 101, and the optical sensor constitute a system. On the encoder disk, a pattern is formed where transmissive portions (allowing light to pass through) and non-transmissive portions (blocking light) are alternately arranged at equal intervals in the circumferential direction. When the encoder disk rotates, a pulse signal is generated whenever the optical sensor detects a transmissive or non-transmissive portion. The generated pulse signal is output to the controller 130 (see reference 130). Figure 4 The controller 130 calculates the rotation amount of the conveying motor 101 based on the pulse signal. In addition, the rotary encoder 75 may be provided in the conveying motor 102 or the conveying roller 60, for example, in addition to the conveying motor 101.

[0070] [Controller 130 and Memory 140]

[0071] The following is for reference Figure 4 The structure of the controller 130 and memory 140 is described below. The controller 130 controls the overall operation of the multifunction printer 10. The controller 130 includes a CPU 131 and an ASIC 135. The memory 140 includes a ROM 132, a RAM 133, and an EEPROM 134. The CPU 131, ASIC 135, ROM 132, RAM 133, and EEPROM 134 are connected via an internal bus 137.

[0072] ROM 132 stores programs used by CPU 131 to control various actions. RAM 133 is used as a storage area or data processing area to temporarily record data or signals used by CPU 131 when executing the above programs. EEPROM 134 stores settings, flags, etc. that should be retained even after power is off.

[0073] The transport motor 101, the feeding motor 102, and the carriage drive motor 103 are connected to the ASIC 135. A drive circuit that controls each motor is assembled in the ASIC 135. The CPU 131 outputs a drive signal for rotating each motor to the drive circuit corresponding to each motor. The drive circuit outputs a drive current corresponding to the drive signal acquired from the CPU 131 to the corresponding motor. As a result, the corresponding motor rotates. That is, the controller 130 controls the feeding motor 102 to cause the feeding section 16 to feed the sheet 12. In addition, the controller 130 controls the transport motor 101 to cause the transport roller pair 59 and the discharge roller pair 44 to transport the sheet 12. In addition, the controller 130 controls the carriage drive motor 103 to cause the carriage 40 to move.

[0074] In addition, an optical sensor of the rotary encoder 75 is connected to the ASIC 135. The controller 130 calculates the amount of rotation of the transport motor 101 on the basis of an electric signal received from the optical sensor of the rotary encoder 75. In addition, the encoder 35 is connected to the ASIC 135. The controller 130 identifies the position of the carriage 40, and whether or not the carriage 40 moves, on the basis of a pulse signal received from the encoder 35.

[0075] In addition, the piezoelectric element 45 is connected to the ASIC 135. The piezoelectric element 45 operates by being supplied with power from the controller 130 via a drive circuit not shown. The controller 130 controls the supply of power to the piezoelectric element 45 to selectively eject ink droplets from the nozzles 39. In addition, a state sensor (not shown) is connected to the ASIC 135. The controller 130 performs image recording processing, abnormality processing, and the like shown below on the basis of a signal received from the state sensor.

[0076] When image recording is performed on the sheet 12, the controller 130 alternately performs a transport process and a printing process. The transport process is a process of causing the transport roller pair 59 and the discharge roller pair 44 to transport the sheet 12 by a prescribed line feed amount. The controller 130 causes the transport roller pair 59 and the discharge roller pair 44 to perform the transport process by controlling the transport motor 101. The printing process is a process of moving the carriage 40 in the right-left direction 9 while controlling the supply of power to the piezoelectric element 45 to cause the head 38 to eject ink droplets from the nozzles 39. During the printing process, the carriage 40 is positioned in a medium passing region (a region between the right end and the left end of the platen 42) facing the platen 42.

[0077] The controller 130 stops the sheet 12 for a certain period between the present transport process and the next transport process. Then, the printing process is performed during the period when the sheet 12 is stopped. That is, the controller 130 performs the printing process while moving the carriage 40 to the right or to the left, and ejecting ink droplets from the nozzles 39 once. As a result, image recording is performed on the sheet 12 once.

[0078] By alternately and repeatedly executing transport and printing processes, the controller 130 is able to record images across the entire area of ​​the paper 12 where image recording is possible. That is, the controller 130 can record images onto a single sheet of paper 12 multiple times.

[0079] Furthermore, the controller 130 is not limited to the above; it may also be that only the CPU 131 performs various processes, only the ASIC 135 performs various processes, or the CPU 131 and ASIC 135 cooperate to perform various processes. Additionally, the controller 130 may be processed by a single CPU 131 or by multiple CPUs 131 sharing the processing. Furthermore, the controller 130 may be processed by a single ASIC 135 or by multiple ASICs 135 sharing the processing.

[0080] [Action of valve unit 91]

[0081] Valve unit 91 changes state between a closed state (closing the atmospheric opening 88) and a released state (opening the atmospheric opening 88). The carriage 40, under control from the controller 130, moves to a pressure release position set outside the medium passage area. In this embodiment, the pressure release position is located to the right of the medium passage area. When the carriage 40 is within the medium passage area, valve unit 91 is in a closed state. When the carriage 40 is in the pressure release position, valve unit 91 is in an open state.

[0082] Figure 5 Frame 151, shown as A, is a component that extends in the vertical direction 7 and the front-back direction 8 (not shown). The abutment portion 152 is a rod-shaped component that protrudes from frame 151 and extends in the left-right direction 9. The positions of the abutment portion 152 in the vertical direction 7 and the front-back direction 8 are the same as the positions of the atmospheric opening 88 in the vertical direction 7 and the left-right direction 9, respectively. The outer diameter of the abutment portion 152 is smaller than the inner diameter of the atmospheric opening 88.

[0083] like Figure 5 As shown in Figure A, during image recording, the carriage 40 moves in the left-right direction 9 from a position separated from the frame 151 and the abutment portion 152. At this time, the helical spring 93 applies force to the right to cause the valve 92 to abut against the atmospheric opening 88. Therefore, the valve unit 91 is in a closed state, closing the atmospheric opening 88.

[0084] On the other hand, such as Figure 5As shown in Figure B, when the carriage 40 moves to the pressure release position, the abutment part 152 presses the valve 92 from the right through the atmospheric opening 88 to the left. At this time, the valve 92 overcomes the force of the coil spring 93 and moves to the left, separating from the atmospheric opening 88. Therefore, the valve unit 91 is in the open state with the atmospheric opening 88 open. When the valve unit 91 is in the open state, the pressure of the gas layer in the storage unit 80 is equal to the atmospheric pressure.

[0085] When image recording resumes, the carriage 40 separates from the frame 151 and the abutment portion 152. At this time, the valve 92 moves to the right by the force of the coil spring 93, abutting against the atmospheric opening 88. Therefore, the valve unit 91 is closed again.

[0086] [Image recording control and pressure release control performed by controller 130]

[0087] In the printing unit 11 configured as described above, the controller 130 performs image recording control by feeding paper 12 and recording images on the fed paper 12. In addition, the controller 130 performs pressure release control by periodically opening the valve unit 91 (opening the atmospheric vent 88).

[0088] For pressure release control, controller 130 counts a value. This count represents the amount of ink discharged from nozzle 39 while valve unit 91 is in the closed state. Memory 140 stores an opening threshold ΔV associated with the count value. The opening threshold ΔV is stored, for example, in RAM 133 within memory 140. Controller 130 opens valve unit 91 when the count value reaches the opening threshold ΔV.

[0089] The following is for reference Figure 6 The flowchart shown illustrates the image recording control and pressure release control performed by the controller 130. When the controller 130 receives a print command, it performs... Figure 6 The control shown. The print command is issued from the operation unit 17 of the multifunction printer 10 (see reference). Figure 1 The controller 130 receives instructions from external devices connected to the multifunction printer 10, including instructions to begin image recording control, information related to the size of the paper 12, and print data for recording images onto the paper 12. At the moment the print instruction is received, the valve unit 91 is in a closed state.

[0090] First, the controller 130 determines whether or not the ink is depleted (S110). In S110, it is determined whether or not the ink 99 stored in the storage portion 80 is empty, using any method. The controller 130 can determine whether or not the ink is depleted, for example, using a method of detecting the position of a float (not shown) provided inside the storage portion 80, or a method of detecting light reflected by a prism (not shown) provided inside the storage portion 80. The amount of the ink 99 determined to be depleted is predetermined. The controller 130 can determine that the ink is depleted when it is determined that the ink 99 is completely empty, or can determine that the ink is depleted when it is determined that the ink 99 is less than a prescribed amount.

[0091] With the condition that it is determined in S110 that the ink is depleted (S110: YES), the controller 130 controls the carriage drive motor 103 to move the carriage 40 to an ink replenishment position (S120). During the carriage 40 is located at the ink replenishment position, the ink is replenished (S130). In S130, the cap 85 is detached from the protruding wall 84, and the ink 99 is injected from a bottle (not shown) into the internal space 81 via the injection port 83. The ink replenishment position can be the same as the pressure release position, or can be different from the pressure release position. With the condition that it is determined in S110 that the ink is not depleted (S110: NO), the controller 130 does not execute S120 and S130, and proceeds to S140.

[0092] Next, the controller 130 performs flushing of the nozzle 39 and feeding of the paper sheet 12 (S140). The flushing of the nozzle 39 is performed by the controller 130 controlling the carriage drive motor 103 to move the carriage 40 to a flushing position, and then controlling the piezoelectric element 45. The feeding of the paper sheet 12 is performed by the controller 130 controlling the feeding motor 102. The flushing of the nozzle 39 and the feeding of the paper sheet 12 are performed in parallel.

[0093] Next, the controller 130 again determines whether or not the ink is depleted (S150). With the condition that it is determined in S150 that the ink is depleted (S150: YES), the controller 130 controls the carriage drive motor 103 to move the carriage 40 to an ink replenishment position (S160). During the carriage 40 is located at the ink replenishment position, the ink is replenished (S170). The processes of S160 and S170 are the same as those of S120 and S130, respectively. With the condition that it is determined in S150 that the ink is not depleted (S150: NO), the controller 130 does not execute S160 and S170, and proceeds to S180. Further, the reason for performing S150 is because there is a case where the ink is depleted due to the flushing of S140 even if it is determined in S110 that the ink is not depleted.

[0094] Next, the controller 130 determines whether the count value is ΔV or more (S180). The process of S180 is an example of a process of determining whether the count value reaches the opening threshold value ΔV. With a condition that the determination in S180 is ΔV or more (S180: YES), the controller 130 performs pressure release and resets the count value to the initial value (S190). With a condition that the determination in S180 is not ΔV or more (S180: NO), the controller 130 does not execute S190 and proceeds to S200.

[0095] In S190, the controller 130 controls the carriage drive motor 103 to move the carriage 40 to the pressure release position. When the carriage 40 is moved to the pressure release position, the valve unit 91 becomes the open state of the open air opening 88 and the pressure of the gas layer of the storage portion 80 becomes equal to the atmospheric pressure. The pressure release is performed with a condition that the carriage 40 is positioned at the pressure release position and no ink is discharged from the nozzle 39. After the pressure release, the controller 130 controls the carriage drive motor 103 to move the carriage 40 to the original position. In parallel with the pressure release, the controller 130 resets the count value to the initial value. The initial value of the count value is, for example, 0.

[0096] Next, the controller 130 updates the count value while performing printing (S210). In S210, the controller 130 performs image recording on one sheet 12. The controller 130 records an image on the entire region of the sheet 12 on which image recording is possible by alternately repeating the conveyance process and the printing process. The controller 130 calculates, for example, the amount of ink discharged from the nozzle 39 when image recording is performed on one sheet 12 based on the print data. The controller 130 adds the amount of ink to the count value.

[0097] Next, the controller 130 determines whether the count value is ΔV or more (S210). Like the process of S180, the process of S210 is a process of determining whether the count value reaches the opening threshold value ΔV. With a condition that the determination in S210 is ΔV or more (S210: YES), the controller 130 performs pressure release and resets the count value to the initial value (S220). The process of S220 is the same as the process of S190. With a condition that the determination in S210 is not ΔV or more (S210: NO), the controller 130 does not execute S220 and proceeds to S230.

[0098] Next, the controller 130 performs ejection of the sheet 12 (S230). In S230, the controller 130 causes the conveyance roller pair 59 and the ejection roller pair 44 to convey the sheet 12 in the conveyance direction 15 and eject the sheet 12 to the ejection tray 21.

[0099] Next, the controller 130 determines whether or not the printing is ended (S240). In S240, the controller 130 determines whether or not the image data included in the print instruction has been recorded on the paper 12.

[0100] With a condition that it is determined in S240 that the printing is not ended (S240: No), the controller 130 performs the feeding of the paper 12 (S250). The process of S250 is the same as the feeding of S140. After that, the controller 130 proceeds to S150. Further, the feeding of the subsequent paper 12 can also be performed in parallel with the ejection of the preceding paper 12 (S230).

[0101] With a condition that it is determined in S240 that the printing is ended (S240: Yes), the controller 130 performs the pressure release and resets the count value to the initial value (S260). The process of S260 is the same as the processes of S190 and S220. Thereby, the controller 130 ends the image recording control and the pressure release control.

[0102] Thus, the controller 130 counts the count value indicating the amount of ink discharged from the nozzle 39 during the closed state of the valve unit 91. The controller 130 causes the valve unit 91 to be in the open state with a condition that the count value reaches the open threshold value AV. The controller 130 resets the count value to the initial value after causing the valve unit 91 to be in the open state in S190, S220, and S260. The controller 130 causes the valve unit 91 to be in the open state with a condition that no ink is discharged from the nozzle 39.

[0103] Further, in this embodiment, the case where the controller 130 normally performs the image recording is described, but the controller 130 can also perform a process of detecting an abnormality while performing the image recording and a process when an abnormality is detected (both not illustrated).

[0104] [Open threshold value AV]

[0105] Hereinafter, the open threshold value AV used for the pressure release control is described. When the volume of the storage portion 80 is set to Vtmax, the maximum amount of ink that can be stored in the storage portion 80 is set to Vi, the atmospheric pressure is set to P, and the meniscus resistance of the ink formed at the nozzle 39 is set to Pm, the open threshold value AV satisfies the following equation (1).

[0106] AV≤(Vtmax-Vi) x Pm / (P-Pm) ··· Equation (1).

[0107] Reference is made to A in Figure 7 and B in Figure 7 for a description of the derivation process of Equation (1). Figure 7 A in Figure 7B in the diagram schematically represents the state of the gas layer in the storage section 80 when the valve unit 91 is in the closed state. Figure 7 In this context, A represents the state before image recording. Figure 7 In this context, B represents the state after the image is recorded. For example... Figure 7 A and Figure 7 As shown in B, ink 99 forms a liquid surface and is stored in the storage section 80. The maximum amount of ink 99 that can be stored in the storage section 80 is located above the opening of the nozzle 39.

[0108] like Figure 7 As shown in Figure A, before image recording, the pressure of the gas layer in the storage unit 80 is atmospheric pressure P, and the volume of the gas layer in the storage unit 80 is V. Figure 7 In the state shown in Figure A, the ink 99 discharged by ΔV (ΔV is a positive value) is recorded by the image, and the change is as follows: Figure 8 The state shown in B is as follows. Assuming that the storage unit 80 is a rigid body that does not deform due to image recording, when ink 99 with a volume of ΔV is discharged, the volume of the gas layer in the storage unit 80 increases by ΔV to become (V+ΔV). If the decrease in pressure of the gas layer in the storage unit 80 at this time is set as ΔP (ΔP is a positive value), then the following equation (2) holds.

[0109] PV=(P-ΔP)(V+ΔV)···Equation (2).

[0110] Equation (3) is derived from equation (2).

[0111] ΔP=P×ΔV / (V+ΔV)···Equation (3).

[0112] When the ink 99 stored in the storage section 80 decreases by ΔV, if the pressure of the storage section 80 is released during a period when the pressure fluctuation (increase) of the gas layer in the storage section 80 is below the meniscus pressure Pm, the meniscus of the ink formed in the nozzle 39 is maintained. On the other hand, the smaller the volume of the gas layer in the storage section 80 (the more ink 99 is stored in the storage section 80), the easier it is for the pressure of the gas layer in the storage section 80 to fluctuate. Therefore, when the ink 99 decreases by ΔV, it can be said that maintaining the meniscus at the maximum amount of ink 99 that can be stored in the storage section 80 is the most difficult.

[0113] Therefore, when ΔV in equation (3) is set as the opening threshold ΔV for pressure release control, if the maximum amount of ink 99 that can be stored in the storage section 80 is stored, and if ΔP in equation (3) is below the meniscus pressure Pm, the meniscus of the ink formed in the nozzle 39 is maintained regardless of the amount of ink 99 stored in the storage section 80. When the maximum amount of ink 99 that can be stored in the storage section 80 is stored, V = Vtmax - Vi.

[0114] By solving the inequality Pm< ΔV, the result of substituting this into the right side of equation (3) is Pm< ΔV, and equation (1) is derived.

[0115] [Specific example of the opening threshold ΔV]

[0116] A specific example of the opening threshold ΔV will be described below. When evaluating the speed of a printer or the like, an ISO chart including four color images is sometimes used. When printing the four color images included in the ISO chart using inks of four colors (magenta, yellow, cyan, and black), the black ink is consumed the most among the inks of the four colors, and the average of the consumption amount of the black ink per one image is 0.020 mL. When this value is adopted as the ink amount required for printing one image, the ink amount required for printing 200 images is 4.2 mL, and the ink amount required for printing 600 images is 12.5 mL.

[0117] The atmospheric pressure is set to 101.3 kPa, and the meniscus pressure resistance of the ink 99 formed at the nozzle 39 is set to 2.5 kPa. The volume of the gas layer of the storage portion 80 varies depending on the opening threshold ΔV in the following manner. Under the above assumptions, when the opening threshold ΔV is set to 0.2 mL, the volume of the gas layer is 7.90 mL or more. Under the same assumptions, when the opening threshold ΔV is set to 0.3 mL, the volume of the gas layer is 11.85 mL or more. Under the same assumptions, when the opening threshold ΔV is set to 0.4 mL, the volume of the gas layer is 15.82 mL. Under the same assumptions, when the opening threshold ΔV is set to 0.5 mL, the volume of the gas layer is 19.75 mL or more. Under the same assumptions, when the opening threshold ΔV is set to 0.6 mL, the volume of the gas layer is 23.70 mL or more.

[0118] When the print sheet number is set to 200 (corresponding to an ink amount of 4.2 mL) and the opening threshold ΔV is set to 0.2 mL, the volume of the storage portion 80 satisfying equation (1) is 12.07 mL or less. When the print sheet number is set to the same and the opening threshold ΔV is set to 0.3 mL, the volume of the storage portion 80 satisfying equation (1) is 16.02 mL or less. When the print sheet number is set to the same and the opening threshold ΔV is set to 0.4 mL, the volume of the storage portion 80 satisfying equation (1) is 19.99 mL or less. When the print sheet number is set to the same and the opening threshold ΔV is set to 0.5 mL, the volume of the storage portion 80 satisfying equation (1) is 23.92 mL or less. When the print sheet number is set to the same and the opening threshold ΔV is set to 0.6 mL, the volume of the storage portion 80 satisfying equation (1) is 27.87 mL or less.

[0119] When the number of print sheets is set to 600 sheets (corresponding to an ink amount of 12.5 mL) and the open threshold AV is set to 0.2 mL, the volume of the storage portion 80 satisfying the expression (1) is 20.40 mL or less. When the number of print sheets is set to the same and the open threshold AV is set to 0.3 mL, the volume of the storage portion 80 satisfying the expression (1) is 24.35 mL or less. When the number of print sheets is set to the same and the open threshold AV is set to 0.4 mL, the volume of the storage portion 80 satisfying the expression (1) is 28.32 mL or less. When the number of print sheets is set to the same and the open threshold AV is set to 0.5 mL, the volume of the storage portion 80 satisfying the expression (1) is 32.25 mL or less. When the number of print sheets is set to the same and the open threshold AV is set to 0.6 mL, the volume of the storage portion 80 satisfying the expression (1) is 36.20 mL or less.

[0120] The multifunction printer 10 preferably does not release the pressure of the storage portion 80 until the speed evaluation using the ISO chart is completed. For example, when the print speed of the multifunction printer 10 is 6 ipm (Image Per Minute: the number of pages that can be output per minute), in the speed evaluation using the ISO chart, 4 color images included in 1 copy are sequentially printed, and then images included in the minimum number of copies whose printing time exceeds 30 seconds (in this case, 4 color images) are printed, so that a total of 8 images are printed. The ink amount required for the printing of the 8 images is 0.16 mL. In view of this, the open threshold AV is set to 0.16 mL or more.

[0121] In addition, in order to downsize the multifunction printer 10, it is necessary to downsize the storage portion 80 as well. In view of the size of the multifunction printer 10, the volume Vtmax of the storage portion 80 is set to 25 mL or less.

[0122] When the number of print sheets is set to 200 sheets (corresponding to an ink amount of 4.2 mL), AV is 0.16 mL or more, Vtmax is 25 mL or less, and the range of the open threshold AV and the volume Vtmax of the storage portion 80 satisfying the expression (1) is Figure 8 the range indicated by the slant line in A in Figure 8 In the slant line portion of A in

[0123] When the number of print sheets is set to 600 sheets (corresponding to an ink amount of 12.5 mL), AV is 0.16 mL or more, Vtmax is 25 mL or less, and the range of the open threshold AV and the volume Vtmax of the storage portion 80 satisfying the expression (1) is Figure 8 the range indicated by the slant line in B inFigure 6 In the slant portion of B in FIG. 19, the opening threshold AV is 0.32 mL or less. Therefore, the volume Vtmax of the storage portion 80 is 25 mL or less, and when the maximum amount Vi of the ink 99 that can be stored in the storage portion 80 is 12.5 mL or less, the opening threshold AV is 0.32 mL or less.

[0124] [Control of opening threshold AV corresponding to ink remaining amount]

[0125] If the opening threshold AV is set to a smaller value within the range satisfying the expression (1), the pressure of the gas layer of the storage portion 80 can be maintained within an appropriate range, and the ink 99 can be stably ejected from the nozzle 39. On the other hand, if the opening threshold AV is set to a larger value within the range satisfying the expression (1), the frequency of pressure release can be reduced, and the printing speed can be increased. In view of these points, the controller 130 can also acquire the remaining amount of the ink 99 stored in the storage portion 80 after resetting the count value to the initial value, and change the opening threshold AV according to the acquired remaining amount.

[0126] The controller 130 counts, for example, a count value (hereinafter referred to as a total count value) different from the above-described count value in order to control the opening threshold AV according to the remaining amount of the ink. The total count value indicates the amount of the ink 99 consumed from the time point at which the maximum amount of the ink 99 is stored in the storage portion 80 to the time point. The controller 130 counts the total count value based on the print data.

[0127] The memory 140 stores a table in which the total count value (or the range of the total count value) and the opening threshold AV are associated with each other. In the table, the smaller the total count value (that is, the more the remaining amount of the ink 99), the smaller the opening threshold AV stored. The controller 130 reads out the opening threshold AV corresponding to the total count value at the time point from the above-described table after resetting the count value to the initial value in S190, S220, and S250 illustrated in FIG. 19, and uses the read-out opening threshold AV in the subsequent pressure release control. The total count value can correspond to the remaining amount of the ink 99 stored in the storage portion 80. By this method, the controller 130 acquires the remaining amount of the ink 99 stored in the storage portion 80, and changes the opening threshold AV according to the acquired remaining amount. Figure 9

[0128] ​When the remaining amount of ink 99 is large, the volume of the gas layer of the storage portion 80 is small. When ink 99 is discharged from the nozzle 39 in this state, the pressure of the gas layer of the storage portion 80 greatly changes. Therefore, the pressure of the gas layer of the storage portion 80 easily deviates from the preferable range, and it is difficult to stably discharge ink 99 from the nozzle 39. Therefore, when the remaining amount of ink 99 is large, a relatively small value is used as the opening threshold AV. Thus, the pressure of the gas layer of the storage portion 80 can be kept within the preferable range, and ink 99 can be stably discharged from the nozzle 39.

[0129] On the other hand, when the remaining amount of ink 99 is small, the volume of the gas layer of the storage portion 80 is large. Even when ink 99 is discharged from the nozzle 39 in this state, the pressure of the gas layer of the storage portion 80 does not greatly change. Therefore, the pressure of the gas layer of the storage portion 80 does not easily deviate from the preferable range, and ink 99 can be stably discharged from the nozzle 39. However, if the opening threshold AV is too small, the frequency of pressure release increases, and the printing speed decreases. Therefore, when the remaining amount of ink 99 is small, a relatively large value is used as the opening threshold AV. Thus, the frequency of pressure release can be reduced, and a decrease in the printing speed can be prevented.

[0130] In this way, by changing the opening threshold AV according to the remaining amount of ink 99, the opening threshold AV that is appropriate for the remaining amount of the storage portion 80 is set. Thus, ink 99 can be stably discharged from the nozzle 39, and a decrease in the printing speed can be prevented.

[0131] Further, the controller 130 can acquire the remaining amount of ink 99 stored in the storage portion 80 by a method other than the above-described methods. The controller 130 acquires the remaining amount of ink 99 stored in the storage portion 80, for example, using a method of detecting the position of a float (not shown) provided inside the storage portion 80, or a method of detecting light reflected by a prism (not shown) provided inside the storage portion 80. The controller 130 can acquire the remaining amount of ink 99 using the same method as in S110 and S150, or using a different method from S110 and S150.

[0132] In this case, the controller 130 does not need to acquire an accurate value of the remaining amount of ink 99, and can acquire an approximate value of the remaining amount of ink 99. As the remaining amount of ink 99, the controller 130 can acquire, for example, two levels (high level and low level), or three levels (high level, intermediate level, and low level).

[0133] [Effects of Embodiments]

[0134] According to the liquid discharge apparatus described above, it is possible to reduce the volume of the storage portion 80 and to make the pressure of the gas in the storage portion 80 atmospheric pressure at an appropriate timing, and thus it is possible to stably discharge liquid from the nozzle 39.

[0135] In addition, the controller 130 resets the count value to the initial value after making the valve unit 91 an open state, and thus is able to make the valve unit 91 an open state each time the count value reaches the open threshold ΔV.

[0136] In addition, the controller 130 resets the count value to the initial value, acquires the remaining amount of the ink 99 stored in the storage portion 80, changes the open threshold ΔV according to the acquired remaining amount, and thus sets the open threshold ΔV appropriate for the remaining amount of the storage portion 80.

[0137] [Modified Example]

[0138] In the above-described embodiment, the valve unit 91 opens or closes the atmospheric air opening 88, but the valve unit 91 can open or close the gas flow path 89. For example, in the storage portion 80 shown in FIG. 9, the valve unit 91 is provided in the middle of the gas flow path 89, and opens or closes the gas flow path 89 without opening or closing the atmospheric air opening 88. In this way, the valve unit 91 can open or close the atmospheric air opening 88 or the gas flow path 89. Figure 10

[0139] In the above-described embodiment, only one storage portion 80 is provided in the recording portion 24, but a plurality of storage portions 80 can be provided in the recording portion 24. For example, as shown in FIG. 10, the recording portion 24 can be provided with four storage portions 80C, 80M, 80Y, and 80B. In addition, in the above-described embodiment, the valve unit 91 changes the state in accordance with the position of the carriage 40, but the valve unit 91 can change the state regardless of the position of the carriage 40. Figure 10

[0140] In the storage portion 80C, cyan ink (not shown) is stored. In the storage portion 80M, magenta ink (not shown) is stored. In the storage portion 80Y, yellow ink (not shown) is stored. In the storage portion 80B, black ink (not shown) is stored. The storage portions 80C, 80M, 80Y, and 80B are arranged in the left-right direction 9. In addition, the storage portions 80C, 80M, 80Y, and 80B can be arranged, for example, in the front-rear direction 8 in addition to the left-right direction 9. In addition, the arrangement order of the storage portions 80C, 80M, 80Y, and 80B is not limited to the order shown in FIG. 10. In addition, the sizes of the respective storage portions 80C, 80M, 80Y, and 80B can be the same or different. Figure 10

[0141] ​​​The atmosphere opening 88 is provided to each of the storage portions 80C, 80M, 80Y, and 80B. In correspondence with each of the atmosphere openings 88, a valve unit 91 is provided. Each of the valve units 91 is provided with a valve 92 and a solenoid 94. Each of the valves 92 is supported by the corresponding solenoid 94 so as to be movable in the up-and-down direction 7. Further, in Figure 10 four valve units 91 are shown in a closed state. In addition, in Figure 10 the illustration of the member that supports the solenoid 94 is omitted. By supplying electric current to the four solenoids 94 from the controller 130, each of the valves 92 is brought into abutment against or separation from the atmosphere opening 88 located at the upper end of the gas flow path 89, independently. When the valve 92 is in abutment with the atmosphere opening 88, the corresponding valve unit 91 is in a closed state. When the valve 92 is separated from the atmosphere opening, the corresponding valve unit 91 is in an open state.

[0142] In the example shown in ​ four valve units 91 are provided in correspondence with the four atmosphere openings 88, but one valve unit 91 can be provided in correspondence with the four atmosphere openings 88. In this case, the valve unit is provided with four valves 92 and one solenoid 94. By supplying electric current to the solenoid 94 from the controller 130, the four valves 92 are simultaneously brought into abutment against or separation from the atmosphere openings 88 located at the upper end of the gas flow path 89.

[0143] In the above-described embodiment, the manner in which the head 38 records an image on the paper sheet 12 is a serial head type in which the head 38 is moved by the carriage 40 and an image is recorded on the paper sheet 12, but can be a line head type in which the recording portion 24 is not provided with the carriage 40 and the head 38 records an image on the paper sheet 12 without moving. In the case of the line head type, the head 38 is provided from the right end to the left end of the medium passing region. In addition, the conveyance processing and the printing processing are performed in parallel and continuously. That is, the paper sheet 12 is conveyed while ink droplets are continuously ejected from the nozzles 39. In addition, in the case of the line head type, the head 38 is supported to a frame of the housing 14. The frame corresponds to the support member.

[0144] In the above-described embodiment, the storage portion 80 is mounted to the carriage 40 and ink is replenished by being injected from the injection port 83. However, the storage portion 80 is not limited to such a structure. For example, the storage portion 80 can be a cartridge that is detachable with respect to the carriage 40. In this case, when the ink stored in the cartridge becomes low or runs out, a new cartridge is replaced.

[0145] In the above-described embodiment, the storage portion 80 is supported to the carriage 40, but can not be supported to the carriage 40. For example, the storage portion 80 can be disposed at a position different from the carriage 40 in the multifunction peripheral 10. In this case, the storage portion 80 and the head 38 are connected by a tube or the like, and the ink stored in the storage portion 80 is supplied to the head 38 via the tube or the like. In this case, at least a part of the storage portion 80 is located at a position higher than the head 38.

[0146] Reference Signs List

[0147] 10... compound machine (liquid discharge device)

[0148] 38... head

[0149] 39... nozzle

[0150] 80... storage section

[0151] 88... atmosphere opening

[0152] 89... gas flow path

[0153] 91... valve unit

[0154] 99... ink (liquid)

[0155] 130... controller

[0156] 140... memory

Claims

1. A liquid discharge apparatus comprising: a head having a nozzle that discharges liquid; a storage portion in which liquid forms a liquid surface and is stored, the storage portion being capable of storing a maximum amount of liquid whose height is located at a position higher than an opening of the nozzle; a gas flow path that communicates a gas layer of the storage portion with the outside through an atmosphere opening that is open to the outside; a valve unit that opens or closes the atmosphere opening or the gas flow path; a storage; and a controller, the storage stores an opening threshold AV, the controller counts a count value that indicates an amount of liquid discharged from the nozzle in a closed state in which the valve unit closes the atmosphere opening or the gas flow path, the controller causes the valve unit to be in an open state in which the valve unit opens the atmosphere opening or the gas flow path, on condition that the count value reaches the opening threshold AV, the controller causes the valve unit to be in the open state on condition that liquid is not discharged from the nozzle, the opening threshold AV satisfies the following expression (1), AV ≤ (Vtmax - Vi) x Pm / (P - Pm) • • • (1), Vtmax is a volume of the storage portion, Vi is a maximum amount of liquid that can be stored in the storage portion, P is an atmospheric pressure, and Pm is a meniscus pressure of the liquid formed at the nozzle.

2. The liquid discharge apparatus according to claim 1, wherein the controller resets the count value to an initial value after causing the valve unit to be in the open state.

3. The liquid discharge apparatus according to claim 2, wherein the controller acquires a remaining amount of liquid stored in the storage portion after resetting the count value to the initial value, and changes the opening threshold AV in accordance with the acquired remaining amount.

4. The liquid discharge apparatus according to any one of claims 1 to 3, wherein Vtmax is 25 mL or less, Vi is 4.2 mL or less, and the opening threshold AV is 0.53 mL or less.

5. The liquid discharge apparatus according to claim 4, wherein the opening threshold AV is 0.16 mL or more.

6. The liquid discharge apparatus according to any one of claims 1 to 3, wherein Vtmax is 25 mL or less, Vi is 12.5 mL or less, and the opening threshold AV is 0.32 mL or less.

7. The liquid discharge apparatus according to claim 6, wherein the opening threshold AV is 0.16 mL or more. ​ ​ ​ ​ ​ ​ wherein ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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