Liquid discharge apparatus

Abstract

A liquid discharge apparatus includes a head having a nozzle, a reservoir configured to store a liquid such that, in a state in which the reservoir stores a maximum storable amount of the liquid, a liquid surface is positioned higher than an opening of the nozzle, and an atmospheric port connecting a gas layer of the reservoir and an outside. An inner diameter d of the nozzle and a head difference h satisfy an expression ρhd / σcosθ ≤ 4 / g, where ρ is a specific gravity of the liquid, σ is a surface tension of the liquid, θ is a contact angle of the liquid in the nozzle, and g is an acceleration of gravity, and the head difference h is a difference in height between a meniscus in the opening of the nozzle and the liquid surface in the state in which the reservoir stores the maximum storable amount of the liquid.

Description

Technical Field

[0001] The present invention relates to a liquid discharge device having a head configured to discharge liquid supplied from a reservoir. Background Technology

[0002] Inkjet pens are known as devices for recording images by discharging ink stored in a cartridge from a nozzle (see Patent Document 1). In such inkjet pens, the liquid surface of the ink stored in the cartridge is located above the nozzle opening. The gas layer in the cartridge is not in communication with the outside, or a valve is provided on the gas passage that connects the gas layer to the outside.

[0003] [List of Citations]

[0004] [Patent Literature]

[0005] [Patent Document 1] Japanese Patent Application Publication JPS55-65560 Summary of the Invention

[0006] [Technical Issues]

[0007] When the gas layer of the ink cartridge is not connected to the outside and ink is consumed, the pressure of the gas layer decreases. As a result, there are concerns that the meniscus formed in the nozzle opening may crack or be damaged. Furthermore, if valves or the like are configured to maintain a constant pressure in the ink cartridge's gas layer while allowing it to connect to the outside, the inkjet head structure may become more complex, or the inkjet head size may need to be increased. On the other hand, when the gas layer of the ink cartridge is always connected to the outside, there is a concern that the meniscus formed in the nozzle opening may be damaged due to head difference (water head difference).

[0008] The present invention was made in view of the above circumstances, and the object of the present invention is to provide a means for maintaining a meniscus formed in the opening of a nozzle while the reservoir storing liquid is in communication with the outside of the reservoir through an atmospheric port.

[0009] [Solution to the problem]

[0010] (1) A liquid discharge device of the present invention includes:

[0011] A head having a nozzle configured to discharge liquid;

[0012] A reservoir configured to store the liquid, such that the liquid has a liquid surface, and such that, with the reservoir storing a maximum storable amount of the liquid, the liquid surface is positioned above the opening of the nozzle, the maximum storable amount being the maximum amount of the liquid that can be stored in the reservoir; and

[0013] An atmospheric port connects the gas layer of the reservoir to the outside of the reservoir.

[0014] The inner diameter d and head difference h of the nozzle satisfy the expression ρhd / σcosθ≤4 / g, where ρ is the specific gravity of the liquid, σ is the surface tension of the liquid, θ is the contact angle of the liquid in the nozzle, and g is the acceleration due to gravity. The head difference h is the height difference between the meniscus formed in the opening of the nozzle and the liquid surface when the reservoir stores the maximum storable amount of the liquid.

[0015] According to the liquid discharge device, a meniscus is maintained in the nozzle opening while the reservoir storing the liquid is connected to the outside of the reservoir through an atmospheric port.

[0016] (2) Preferably, the inner diameter d is not less than 5 μm, and the inner diameter d is less than 20 μm; and

[0017] The head difference h does not exceed 664 mm.

[0018] (3) Preferably, the inner diameter d is not less than 20 μm, and the inner diameter d is less than 30 μm; and

[0019] The head difference h does not exceed 443mm.

[0020] (4) Preferably, the inner diameter d is not less than 30 μm, and the inner diameter d is less than 50 μm; and

[0021] The head difference h does not exceed 266mm.

[0022] (5) Preferably, the inner diameter d is not less than 50 μm, and the inner diameter d is less than 80 μm; and

[0023] The head difference h does not exceed 166mm.

[0024] (6) Preferably, the inner diameter d is not less than 80 μm, and the inner diameter d is less than 90 μm; and

[0025] The head difference h does not exceed 148mm.

[0026] (7) Preferably, the inner diameter d is not less than 90 μm, and the inner diameter d is less than 100 μm; and

[0027] The head difference h does not exceed 133mm.

[0028] (8) Preferably, the inner diameter d is not less than 100 μm, and the inner diameter d is less than 110 μm; and

[0029] The head difference h does not exceed 121mm.

[0030] (9) Preferably, the inner diameter d is not less than 110 μm, and the inner diameter d is less than 120 μm; and

[0031] The head difference h does not exceed 111 mm.

[0032] (10) Preferably, the inner diameter d is not less than 1 μm, and the inner diameter d is less than 133 μm; and

[0033] The head difference h does not exceed 100mm.

[0034] (11) Preferably, the inner diameter d is not less than 1 μm, and the inner diameter d is less than 66 μm; and

[0035] The head difference h is greater than 100mm and the head difference h does not exceed 200mm.

[0036] (12) Preferably, the inner diameter d is not less than 1 μm, and the inner diameter d is less than 33 μm; and

[0037] The head difference h is greater than 200mm and the head difference h does not exceed 400mm.

[0038] (13) Preferably, the inner diameter d is not less than 1 μm, and the inner diameter d is less than 22 μm; and

[0039] The head difference h is greater than 400mm and the head difference h does not exceed 600mm.

[0040] (14) Preferably, the viscosity of the liquid is not less than 2 cps and the viscosity of the liquid is less than 11 cps.

[0041] (15) Preferably, the liquid discharge device further includes a carriage configured to move with the head and the reservoir mounted on the carriage.

[0042] (16) Preferably, the liquid discharge device further includes a carriage configured to move when the head is mounted on the carriage.

[0043] The storage container is not mounted on the carriage; and

[0044] The reservoir and the head are connected by a liquid channel.

[0045] (17) Preferably, the carriage is configured to move in the scanning direction; and

[0046] The head is configured to discharge the liquid while the carriage is moving in the scanning direction.

[0047] (18) Preferably, the liquid discharge device further includes a gas passage continuous with the atmospheric port.

[0048] The gas channel has at least one of a labyrinth structure and a semi-permeable membrane.

[0049] [Beneficial effects of the invention]

[0050] According to the present invention, a meniscus formed in the nozzle opening is maintained while the reservoir storing the liquid is in communication with the outside of the reservoir through an atmospheric port. Attached Figure Description

[0051] Figure 1 This is a perspective view of a multifunctional peripheral device 10, which is an example of an embodiment of the present invention.

[0052] Figure 2 It is a vertical sectional view schematically depicting the internal structure of the printer section 11.

[0053] Figure 3 It is a vertical cross-sectional view depicting the section 24 when it is cut by a plane orthogonal to the front-back direction 8.

[0054] Figure 4 This is a functional block diagram of the multi-functional peripheral device 10;

[0055] Figure 5 This is a flowchart illustrating the image recording control performed by the multi-functional peripheral device 10.

[0056] Figure 6A and Figure 6B Each is a view used to illustrate the meniscus formed within the opening of nozzle 39, wherein Figure 6A It is a schematic view depicting the reservoir 80 and the nozzle 39, and Figure 6B It is a view depicting the state in which a meniscus is formed in the opening of nozzle 39.

[0057] Figure 7 It is a view depicting the range of inner diameter (d) and head difference (h) satisfying expression (1).

[0058] Figure 8A and Figure 8B Each is a view depicting a specific example of the range in which the inner diameter (d) and head difference (h) satisfy expression (1), where Figure 8A It is a view depicting the range of head difference (h) relative to each range of the inner diameter (d), and Figure 8BIt is a view depicting the range of the inner diameter (d) relative to each range of the head difference (h).

[0059] Figure 9 It is a vertical cross-sectional view of the section when the modified recording part 24 is cut by a plane orthogonal to the front-back direction 8.

[0060] Figure 10 This is a schematic diagram showing the arrangement of the modified storage unit 80.

[0061] Figure 11A and Figure 11B Each is a perspective view depicting the upper wall 82 of a modified storage container 80, wherein Figure 11A This is a perspective view of the atmospheric communication channel 161 having a labyrinth structure 164, and Figure 11B This is a perspective view of the atmospheric communication channel 161 having a labyrinth structure 164 and a semi-permeable membrane 165.

[0062] List of reference numerals

[0063] 10: Multifunctional peripheral equipment (liquid discharge equipment)

[0064] 38: Head

[0065] 39: Nozzle

[0066] 40: Carriage

[0067] 80: Storage

[0068] 88: Atmospheric Open Port (Atmospheric Port)

[0069] 90: Ink (liquid)

[0070] 151: Tube (liquid channel)

[0071] 161: General connecting channel (gas channel)

[0072] 164: Maze Structure

[0073] 165: Semi-permeable membrane Detailed Implementation

[0074] In the following description, embodiments of the present invention will be described. Note that the embodiments described below are merely examples of the present invention; needless to say, these embodiments can be appropriately modified without altering the spirit of the invention. Furthermore, in the following description, advancement or movement (forward movement) from the starting point to the ending point of the arrow is expressed as "orientation," and back and forth along the line connecting the starting and ending points of the arrow is expressed as "direction." Additionally, in the following description, the multi-functional peripheral device 10 is operably installed in a state (…). Figure 1Using the state of the device as a reference, the vertical direction 7 is defined; when the side with the opening 13 is defined as the front surface 23, the front-back direction 8 is defined; and when the multifunctional peripheral device 10 is viewed from the front, the left-right direction 9 is defined. The vertical direction 7, the front-back direction 8, and the left-right direction 9 are orthogonal to each other.

[0075] [Overall Structure of Multifunctional Peripheral Device 10]

[0076] like Figure 1 As depicted, the multi-function peripheral device 10 (an example of a "liquid discharge device") has a housing (outer shell) 14, which has a generally rectangular parallelepiped shape. A printer portion 11 is disposed at the lower part of the housing 14. The multi-function peripheral device 10 has various functions, such as faxing and printing. As a printing function, the multi-function peripheral device 10 has a sheet 12 (paper sheet 12; see [link]) in the inkjet system. Figure 2 The device records images on one surface of the sheet 12. Note that the multi-functional peripheral device 10 can also be configured to record images on both surfaces of the sheet 12. An operation section 17 is provided on the upper part of the housing 14. This operation section 17 consists of buttons, a liquid crystal display, etc. The buttons are configured to instruct image recording, execute various settings, etc., and the liquid crystal display is configured to display various information. In this embodiment, the operation section 17 consists of a touch panel that has both button and liquid crystal display functions.

[0077] like Figure 2 As depicted, the printer section 11 has a feed tray 20, a feed section 16, an outer guide member 18, an inner guide member 19, a transfer roller pair 59, an discharge roller pair 44, a pressure plate 42, a recording section 24, and an encoder 35 (see [reference]) arranged inside the housing 14. Figure 4 ), rotary encoder 75 (see Figure 4 ), controller 130 (see Figure 4 ) and memory 140 (see Figure 4 Inside the housing 14, various status sensors (not shown in the figure) are arranged, which are configured to detect the status of the multifunctional peripheral device 10 and output signals based on the detection results.

[0078] [Feed tray 20]

[0079] like Figure 1 As depicted, an opening 13 is formed on the front surface 23 of the printer section 11. The feed tray 20 can be inserted and removed relative to the housing 14 via the opening 13 by moving in the front-rear direction 8. The feed tray 20 can be in a feed position where it is mounted in the housing 14. Figure 1 and Figure 2The feed tray 20 is moved between the position depicted in the diagram and the non-feed position where it is removed (disassembled) from the housing 14. The feed tray 20 is inserted rearward relative to the housing 14 to move to the feed position, and the feed tray 20 is pulled forward relative to the housing 14 to move to the non-feed position.

[0080] The feed tray 20 is a box-shaped component with an open top and is configured to store the sheet 12. For example... Figure 2 As depicted, multiple sheets 12 are supported by the base plate 22 of the feed tray 20 in an overlapping state. The discharge tray 21 is positioned above the front of the feed tray 20. The sheets 12, whose images have been recorded by the recording section 24 and are subsequently discharged, are supported by the upper surface of the discharge tray 21. When the feed tray 20 is in the feed position, the sheets 12 supported by the feed tray 20 are allowed to be fed into the transport path 65.

[0081] [Feed section 16]

[0082] like Figure 2 As depicted, the feed section 16 is positioned below the recording section 24 and above the base plate 22 of the feed tray 20. The feed section 16 includes a feed roller 25, a feed arm 26, a drive transmission mechanism 27, and a shaft 28. The feed roller 25 is rotatably supported at the front end of the feed arm 26. The feed arm 26 rotates about the shaft 28, which is located at its base, in the direction of arrow 29. Thus, the feed roller 25 can contact and separate from the feed tray 20 or the sheet 12 supported by the feed tray 20.

[0083] The feed roller 25 is fed by the feed motor 102 (see...) Figure 4 The feed roller 25 is rotated by a driving force, which is transmitted to the feed roller 25 through a drive transmission mechanism 27 consisting of multiple meshing gears. Thus, the uppermost sheet 12 of the sheet 12 supported by the base plate 22 of the feed tray 20 at the feed position, which is in contact with the feed roller 25, is fed into the conveying path 65. Note that the drive transmission mechanism 27 is not limited to or constrained by the meshing configuration of the multiple gears; for example, the drive transmission mechanism 27 may be a belt extending or crossing between the shaft 28 and the shaft of the feed roller 25.

[0084] [Teleportation Path 65]

[0085] like Figure 2 As depicted, the conveying path 65 extends from the rear end portion of the feed tray 20. The conveying path 65 includes a curved portion 33 and a straight portion 34. The curved portion 33 extends upward while making a U-shaped turn from the rear to the front. The straight portion 34 extends generally along the front-rear direction 8.

[0086] The curved portion 33 is formed by an outer guide member 18 and an inner guide member 19 facing each other or opposite each other, with a predetermined interval between the outer guide member 18 and the inner guide member 19. The outer guide member 18 and the inner guide member 19 are arranged to extend in the left-right direction 9. At the position where the recording portion 24 is arranged, a straight portion 34 is formed by the recording portion 24 and the pressure plate 42, which face each other and have a predetermined interval between them.

[0087] The sheet 12, supported by the feed tray 20, is conveyed via the feed rollers 25 in the curved section 33 and reaches the transfer roller pair 59. The sheet 12, held or clamped by the transfer roller pair 59, is conveyed forward toward the recording section 24 in the straight section 34. The recording section 24 records an image on the sheet 12, which has reached a position directly below the recording section 24. The sheet 12 with the recorded image is conveyed forward in the straight section 34 and discharged onto the discharge tray 21. As described above, along the... Figure 2 The arrow with a dotted line in the middle indicates the conveying orientation 15 for conveying sheet 12.

[0088] [Conveyor roller pair 59 and discharge roller pair 44]

[0089] like Figure 2 As depicted, the conveyor roller pair 59 is arranged in the straight section 34. In the straight section 34, the discharge roller pair 44 is arranged on the downstream side of the conveyor orientation 15 relative to the conveyor roller pair 59.

[0090] The conveyor roller pair 59 includes a conveyor roller 60 and a clamping roller 61, which is positioned below the conveyor roller 60 and faces it. The clamping roller 61 is pressed against the conveyor roller 60 by an elastic member (not shown) such as a helical spring. The conveyor roller pair 59 is capable of clamping or holding the sheet 12 therebetween.

[0091] The discharge roller pair 44 includes a discharge roller 62 and a toothed roller 63, the toothed roller 63 being positioned above the discharge roller 62 to face it. The toothed roller 63 is pressed against the discharge roller 62 by an elastic member (not shown) such as a helical spring. The discharge roller pair 44 is capable of clamping or holding the sheet 12 therebetween.

[0092] From the transmission motor 101 (see Figure 4When a driving force is applied to the conveyor roller 60 and the discharge roller 62, the conveyor roller 60 and the discharge roller 62 rotate. When the conveyor roller 60 rotates with the sheet 12 held by the conveyor roller pair 59, the sheet 12 is conveyed by the conveyor roller pair 59 along the conveying orientation 15 and is conveyed onto the pressure plate 42. When the discharge roller 62 rotates with the sheet 12 held by the discharge roller pair 44, the sheet 12 is conveyed by the discharge roller pair 44 along the conveying orientation 15 and is discharged onto the discharge tray 21. Note that a common motor can be used as both the conveyor motor 101 and the feed motor 102. In this case, a configuration is provided in which the drive transmission path from the common motor to each roller is switchable.

[0093] Note that the mechanism or component configured to convey sheet 12 is not limited to the roller pair as described above. For example, a conveyor belt may be arranged in place of the conveyor roller pair 59 and the discharge roller pair 44.

[0094] [Pressure plate 42]

[0095] like Figure 2 As depicted, the pressure plate 42 is arranged in the straight section 34 of the transport path 65. The pressure plate 42 faces the recording section 24 in the vertical direction 7. The pressure plate 42 supports the sheet 12 being transported in the transport path 65 from below. The sheet 12 being transported in the transport path 65 passes through the area between the right and left ends of the pressure plate 42 in the horizontal direction 9 (hereinafter referred to as the "medium passage area").

[0096] [Record Section 24]

[0097] like Figure 2 As depicted, the recording section 24 is positioned above the pressure plate 42, thus facing the pressure plate 42. The recording section 24 includes a carriage 40, a head 38, and a storage unit (storage section, storage device) 80.

[0098] The carriage 40 is supported by two guide rails 56 and 57, enabling it to move in a left-right direction 9 (an example of a "scanning direction") orthogonal to the transport orientation 15. The two guide rails 56 and 57 are arranged at a distance from each other in the front-back direction 8. The carriage 40 is capable of moving in the left-right direction 9 between a position on the right side and a position on the left side of the media passage area. Note that the direction of movement of the carriage 40 is not limited to the left-right direction 9, and can also be a direction intersecting the transport orientation 15.

[0099] Guide rail 56 is arranged on the upstream side of the conveying orientation 15 relative to head 38. Guide rail 57 is arranged on the downstream side of the conveying orientation 15 relative to head 38. Guide rails 56 and 57 are supported by a pair of side frames (not shown in the figure), which are arranged in the left-right direction 9 outside the straight portion 34 of the conveying path 65. The driving force is transferred from the carriage drive motor 103 (see...) Figure 4 When applied to the carriage 40, the carriage 40 is moved.

[0100] Encoder 35 (see) Figure 4 The encoder 35 is arranged in guide rail 56 or guide rail 57. The encoder 35 includes: an encoder bar extending in the left-right direction 9; and an optical sensor disposed on the carriage 40 at a position facing the encoder bar. A pattern is formed in the encoder bar in which light-transmitting portions, each configured to allow light to pass through, and light-blocking portions, each configured to block light, are arranged alternately at equal pitch in the left-right direction 9. The optical sensor detects the light-transmitting portions and the light-blocking portions, thereby detecting a pulse signal. The pulse signal is a signal based on the position of the carriage 40 in the left-right direction 9. The pulse signal is output to the controller 130 (see...). Figure 4 ).

[0101] The head 38 is supported by a carriage 40. The lower surface 68 of the head 38 is exposed downwards and faces the pressure plate 42. The head 38 is provided with: multiple nozzles 39; ink channels 37; and piezoelectric elements 45 (see...). Figure 4 ).

[0102] The plurality of nozzles 39 open in the lower surface 68 of the head 38. An ink channel 37 connects to or links the reservoir 80 and the plurality of nozzles 39. A piezoelectric element 45 (see [link]). Figure 4 This causes a portion of the ink channel 37 to deform, thereby causing droplets (ink droplets) of ink to be ejected or sprayed downwards from the nozzle 39. The piezoelectric element 45 is supplied by the controller 130 (see...). Figure 4 The head 38 is powered or activated by the power supply. In this way, the head 38 has the plurality of nozzles 39 that discharge or jet ink ("liquid" example).

[0103] With the reservoir 80 mounted in the carriage 40, the reservoir 80 is supported by the carriage 40. The reservoir 80 has an internal space 81. Ink 90 is stored in the internal space 81. In this embodiment, the recording section 24 includes a reservoir 80. Black ink 90 (black ink) is stored in the reservoir 80. Note that the color of the ink 90 stored in the reservoir 80 is not limited to black.

[0104] The reservoir 80 is located above the head 38. Note that although the entire reservoir 80 is located above the head 38 in this embodiment, it is also permissible for a portion of the reservoir 80 to be located above the head 38, and another portion of the reservoir 80, distinct from this portion, to be located at a height equal to or below the height of the head 38. The internal space 81 of the reservoir 80 communicates with the plurality of nozzles 39 via ink channels 37. Thus, ink 90 is supplied from the internal space 81 to the plurality of nozzles 39.

[0105] An inlet port 83 is provided in the upper wall 82 of the reservoir 80, through which ink 90 is poured or supplied to the internal space 81. The inlet port 83 penetrates the upper wall 82 in the thickness direction to communicate (connect) the internal space 81 with the outside of the reservoir 80. A protruding wall 84 is provided in the upper surface of the upper wall 82 around the inlet port 83 (see...). Figure 3 The cap 85 engages with the protruding wall 84, thereby closing the inlet port 83. When the cap 85 is removed or detached from the protruding wall 84, the inlet port 83 is exposed to the outside. In this state, a bottle (not shown) is inserted into the inlet port 83, and ink 90 is poured from the bottle into the interior space 81 via the inlet port 83. Note that the inlet port 83 can be located at a different location than the upper wall 82, provided that such a location allows communication between the upper part of the interior space 81 and the outside.

[0106] like Figure 3 As depicted, an atmospheric opening port (atmospheric port) 88 is provided on the upper wall 82 of the reservoir 80. Air enters the portion of the internal space 81 of the reservoir 80 where ink 90 is not present. The portion of the internal space 81 where air has entered is referred to as the gas layer. The atmospheric opening port 88 connects the gas layer of the reservoir 80 to the outside of the reservoir 80.

[0107] [Rotary Encoder 75]

[0108] Figure 4 The rotary encoder 75 depicted consists of an encoder disk and an optical sensor, the encoder disk being mounted on the transmission motor 101 (see [reference]). Figure 4 The encoder disk is mounted on a shaft and configured to rotate together with the transmission motor 101. A pattern is formed in the encoder disk in which transmissive portions, each configured to allow light to pass through, and non-transmissive portions, each configured to prevent light from passing through, are arranged alternately at equal pitches in the circumferential direction of the encoder disk. As the encoder disk rotates, a pulse signal is generated each time a transmissive or non-transmissive portion is detected by the optical sensor. The generated pulse signal is output to the controller 130 (see [link to controller 130]). Figure 4The controller 130 calculates the rotation of the transmission motor 101 based on the pulse signal. Note that the rotary encoder 75 can be set in a different location than the transmission motor 101, for example, on the feed motor 102, the transmission roller 60, etc.

[0109] [Controller 130 and memory 140]

[0110] In the following text, reference will be made to Figure 4 The configuration of controller 130 and memory 140 is described below. Controller 130 is configured to control the entire operation of multi-function peripheral device 10. Controller 130 includes CPU 131 and ASIC 135. Memory 140 includes ROM 132, RAM 133, and EEPROM 134. CPU 131, ASIC 135, ROM 132, RAM 133, and EEPROM 134 are interconnected via internal bus 137.

[0111] ROM 132 stores programs that cause CPU 131 to control various operations. RAM 133 is used as a temporary storage area for data and / or signals that will be used when CPU 131 executes the program, or as a working area for data processing. EEPROM 134 stores settings and / or flags that must be retained or stored even after power is cut off.

[0112] The conveyor motor 101, feed motor 102, and carriage drive motor 103 are connected to the ASIC 135. Drive circuits are installed in the ASIC 135, with each drive circuit controlling one of the motors. The CPU 131 outputs drive signals to the drive circuit corresponding to one of the motors, each drive signal causing the motor to rotate. Each drive circuit outputs drive current to the motor corresponding to its drive signal from the CPU 131. Thus, the corresponding motor rotates. Specifically, the controller 130 controls the feed motor 102 to cause the feed section 16 to feed the sheet 12. Furthermore, the controller 130 controls the conveyor motor 101 to cause the conveyor roller pair 59 and the discharge roller pair 44 to convey the sheet 12. Additionally, the controller 130 controls the carriage drive motor 103 to move the carriage 40.

[0113] Furthermore, the optical sensor of the rotary encoder 75 is connected to the ASIC 135. The controller 130 calculates the rotation amount of the transmission motor 101 based on the electrical signals received from the optical sensor of the rotary encoder 75. Additionally, the encoder 35 is connected to the ASIC 135. The controller 130 identifies the position of the carriage 40 and / or the presence or absence of movement of the carriage 40 based on pulse signals received from the encoder 35.

[0114] Furthermore, piezoelectric element 45 is connected to ASIC 135. Piezoelectric element 45 is driven or activated by power from controller 130 via a drive circuit (not shown). Controller 130 controls the power supply to piezoelectric element 45 to selectively eject or spray ink droplets from the plurality of nozzles 39. Additionally, a status sensor (not shown) is connected to ASIC 135. Controller 130 performs image recording processing, anomaly handling, etc., which will be described later, based on signals received from the status sensor.

[0115] While the controller 130 is recording an image on the sheet 12, the controller 130 alternately performs transport processing and printing processing. Transport processing involves causing the transport roller pair 59 and the discharge roller pair 44 to transport the sheet 12 only with a predetermined line feed. The controller 130 controls the transport motor 101, thereby causing the transport roller pair 59 and the discharge roller pair 44 to perform transport processing. Printing processing involves controlling the power supply to the piezoelectric element 45 while moving the carriage 40 in the left-right direction 9, thereby causing the head 38 to discharge ink droplets from the nozzle 39. During printing processing, the carriage 40 is located in the media passage area (the area between the right and left ends of the pressure plate 42) and faces or is opposite the pressure plate 42.

[0116] During the time interval between the currently executing transport process (current transport process) and the next transport process to be executed (next transport process), the controller 130 stops the sheet 12 for a predetermined time period. Furthermore, the controller 130 performs printing processing during the time the sheet 12 is stopped. That is, in the printing process, the controller 130 performs a one-pass operation, which causes ink droplets to be ejected from the nozzle 39 while simultaneously causing the carriage 40 to move left or right. Thus, image recording is performed on the sheet 12 for the one-pass operation.

[0117] The controller 130 is capable of recording images over the entire recordable area of ​​the sheet 12 by alternately and repeatedly performing transfer and printing processes. That is, the controller 130 records images on a sheet 12 through multiple passes (performing multiple passes). In this manner, in the multi-function peripheral device 10, the carriage 40 moves together with the head 38 mounted on the carriage 40 and the reservoir 80. The carriage 40 moves in the left-right direction 9, and while the carriage 40 moves in the left-right direction 9, the head 38 discharges ink.

[0118] Note that controller 130 is not limited to or construed as described above. Controller 130 may be configured such that only CPU 131 performs various processes, or only ASIC 135 performs various processes, or CPU 131 and ASIC 135 perform various processes in a cooperative manner. Alternatively, controller 130 may be configured such that a single CPU 131 performs a process, or multiple components of CPU 131 perform a process in a shared manner. Again, alternatively, controller 130 may be configured such that a single ASIC 135 performs a process, or multiple components of ASIC 135 perform a process in a shared manner.

[0119] [Image recording control performed by controller 130]

[0120] In the printer section 11 constructed as described above, a series of image recording controls are executed by the controller 130, through which the sheet 12 is conveyed and an image is recorded on the conveyed sheet 12. Reference will be made below. Figure 5 The flowchart depicted illustrates the image recording control performed by the controller 130.

[0121] When image recording control is not performed, the carriage 40 is located outside the media passage area in the left-right direction 9 (this position is referred to as the "maintenance position"), and the carriage 40 does not face the pressure plate 42.

[0122] The print command is transmitted from the operation section 17 of the multifunction peripheral device 10 (see...). Figure 1 The print command is sent to the controller 130 via an external device or apparatus connected to the multifunction peripheral device 10. The print command includes a command to start image recording control, information about the size of the sheet 12, and print data for image recording to be performed on the sheet 12.

[0123] When the controller 130 receives a printing command (step S10: Yes), the controller 130 executes the feeding of the sheet 12 supported by the feed tray 20 (step S20).

[0124] In step S20, the controller 130 drives the feed motor 102. As a result, the feed roller 25 feeds the sheet 12, supported by the feed tray 20, onto the conveying path 65. Furthermore, the controller 130 drives the transfer motor 101. Thus, when the leading edge of the sheet 12 fed by the feed roller 25 onto the conveying path 65 reaches the transfer roller pair 59, the transfer roller pair 59 transfers the sheet 12 along the transfer orientation 15.

[0125] Next, the controller 130 drives the carriage drive motor 103, thereby moving the carriage 40 from the maintenance position to the starting position. The starting position is the position at which the carriage 40 begins to move during the printing process (step S30), and is determined based on the printing data. In step S20, the feeding operation of the sheet 12 and the moving operation of the carriage 40 are performed in parallel.

[0126] Next, the controller 130 performs the printing process (step S30). In the printing process of step S30, the controller 130 performs a single pass. That is, while the controller 130 moves the carriage 40 from the starting position, the controller 130 causes ink droplets to be ejected from the nozzle 39. Note that it is permissible for the carriage 40, which has already started moving from the maintenance position in step S20, not to stop at the starting position, but to continue moving for the printing process. Of course, it is permissible for the carriage 40 to temporarily stop at the starting position.

[0127] Next, the controller 130 determines whether to end image recording on the current sheet 12 based on the information about the size of the sheet 12 included in the print command and / or the print data (step S40).

[0128] In step S40, if image recording on the current sheet 12 has not ended (step S40: No), a transfer process is performed (step S50). In the transfer process of step S50, the controller 130 drives the transfer motor 101, thereby causing the transfer roller pair 59 and the discharge roller pair 44 to transfer the sheet 12 at a predetermined feed rate. Afterwards, the control of the controller 130 proceeds to step S30.

[0129] In step S40, when the image recording on the current sheet 12 ends (step S40: Yes), the controller 130 causes the conveyor roller pair 59 and the discharge roller pair 44 to convey the sheet 12 on the conveyor orientation 15, thereby discharging the sheet 12 to the discharge tray 21 (step S60).

[0130] Next, the controller 130 determines whether there is still image data included in the print command but not yet recorded on the sheet 12, i.e., whether there is image recording to be performed on the next page (step S70).

[0131] If there is an image recording to be performed on the next page (step S70: Yes), the controller 130 proceeds to step S20. In this case, the controller 130 feeds the subsequent sheet 12 from the feed tray 20 to the transport path 65 (step S20). Note that the feeding of the subsequent sheet 12 (step S20) can be performed in parallel with the discharge of the previous sheet 12 (step S60). If there is no image recording to be performed on the next page (step S70: No), the controller 130 terminates the series of image recording controls.

[0132] Note that while the normal image recording process of controller 130 has been described here, it is also permissible for controller 130 to perform anomaly detection processing and processing to be performed if an anomaly has been detected while performing image recording (each of these processes is not depicted in the accompanying drawings).

[0133] [Conditions for maintaining the meniscus]

[0134] In the following text, regarding the image recording performed by the multi-functional peripheral device 10, the conditions for maintaining the meniscus of the nozzle 39 of the head 38 will be explained. Figure 6A The reservoir 80 and nozzle 39 are schematically depicted in the image. Although in... Figure 6A For ease of understanding, the accompanying drawings depict one nozzle 39, but in reality, there are multiple nozzles 39.

[0135] like Figure 6A As depicted, ink 90 is stored in reservoir 80 while forming the liquid surface LS. Figure 6A In the figure, LS is used as the reference numeral. max The dotted line depicts the liquid surface LS when the maximum storable amount of ink 90 (i.e., the maximum amount of ink 90 that can be stored in the reservoir 80) is stored in the reservoir 80. In this embodiment, the maximum storable amount corresponds to the amount when the ink 90 fills the internal space 81 and the liquid surface LS of the ink 90 is coplanar with the upper end of the atmospheric opening port 88 (or the upper surface 80u of the reservoir 80). When the maximum storable amount of ink 90 is stored in the reservoir 80, the height of the liquid surface LS is above the opening of the nozzle 39 (i.e., at a position higher than the opening of the nozzle 39). The atmospheric opening port 88 connects the gas layer of the reservoir 80 (the portion of the internal space 81 where ink 90 is not present) to the outside.

[0136] like Figure 6BAs depicted, the ink 90 in the opening of the nozzle 39 forms a meniscus with a downwardly projecting or convex shape. The downward-acting gravity F1 and the upward-acting surface tension F2 due to the contact between the ink 90 and the inner surface of the nozzle 39 act on the ink 90 near the opening of the nozzle 39. The meniscus formed in the opening of the nozzle 39 is maintained as long as the surface tension F2 is not less than the gravity F1.

[0137] The specifications are as follows: the inner diameter of nozzle 39 is (d), the head difference (water head difference) is (h), the head difference is the height difference between the meniscus formed in the opening of nozzle 39 (i.e., the position of the base of the meniscus or the position of the opening of nozzle 39) and the liquid surface LS in the maximum amount (maximum storable amount) of ink 90 that can be stored in reservoir 80; the specific gravity (specific gravitational force) of ink 90 is (ρ); the surface tension of ink 90 is (σ); the contact angle defined between ink 90 and the inner surface of nozzle 39 is (θ); and the gravitational acceleration is (g). The gravitational force F1 acting downward on the ink near the opening of nozzle 39 is given by the following formula: πd 2 / 4×ρgh. The surface tension F2 acting upward on the ink near the opening of nozzle 39 is given by the following formula: πdσcosθ. Substituting these formulas and rearranging them in the relational expression F1≤F2, we obtain the following expression (1):

[0138] ρhd / σcosθ≤4 / g…expression(1).

[0139] In the multi-functional peripheral device 10, given the specific gravity (ρ) of ink 90, the surface tension (σ) of ink 90, and the contact angle (θ) defined between ink 90 and the inner surface of nozzle 39, the inner diameter (d) and head difference (h) of nozzle 39 are determined to satisfy expression (1). When the inner diameter (d) is taken as the horizontal axis and the head difference (h) as the vertical axis, the range satisfying expression (1) is... Figure 7 The lower left side of the curve shown (shaded area). The combination of the values ​​of the inner diameter (d) and the head difference (h) is located at... Figure 7 In the case of the shaded area shown, the meniscus formed in the opening of the nozzle 39 is maintained.

[0140] The following will provide specific examples of how the inner diameter (d) and head difference (h) of nozzle 39 satisfy the range of expression (1). The ink used in printers of inkjet systems such as the multifunction peripheral device 10 has a viscosity, for example, not less than 2 cps and less than 11 cps. As ink, for example, a water-based ink containing not less than 50% and not more than 70% water is used. The specific gravity (ρ) of the ink is, for example, not less than 1.03 g / cm³. 3 And not exceeding 1.13 g / cm 3The surface tension σ of the ink is, for example, not less than 25 mN / m and not more than 37 mN / m. The contact angle (θ) defined between the inner surface of the nozzle and the ink is, for example, not less than 25° and not more than 50°.

[0141] The surface tension (σ) of the ink is obtained, for example, by using the Wilhelmy method. The contact angle (θ) defined between the inner surface of the nozzle and the ink is obtained by measuring the contact angle defined when the ink is dropped onto a plate made of the same material as the nozzle, for example, using the θ / 2 method (half-angle method).

[0142] In the following text, "the specific gravity (ρ) of ink is 1.03 g / cm³". 3 The set of conditions, namely, "the surface tension (σ) of the ink is 37 mN / m" and "the contact angle (θ) between the inner surface of the nozzle and the ink is 25°", is called the "first condition", and "the specific gravity (ρ) of the ink is 1.13 g / cm³". 3 The set of conditions that "the surface tension (σ) of the ink is 25 mN / m" and "the contact angle (θ) between the inner surface of the nozzle and the ink is 50°" is called the "second condition".

[0143] Under the condition that the first condition is met in the multi-functional peripheral device 10, the range that satisfies expression (1) is: Figure 8A and Figure 8B The lower left side of the curve shown. (As shown) Figure 8A As shown, eight regions 211 to 218 are defined on the lower left side of the curve. Figure 8B As shown, four regions 221 to 224 are set on the lower left side of the curve. When the combination of the values ​​of the inner diameter (d) and the head difference (h) is in any of the regions 211 to 218 and 221 to 224, expression (1) is satisfied, and the meniscus formed in the opening of the nozzle 39 is maintained.

[0144] Figure 8A The region 211 shown is a region with an inner diameter (d) of not less than 5 μm and less than 20 μm and a head difference (h) of not more than 664 mm. When the inner diameter (d) is not less than 5 μm and less than 20 μm, by making the head difference (h) not more than 664 mm, expression (1) is satisfied, and the meniscus formed in the opening of the nozzle 39 is maintained.

[0145] Region 212 is a region with an inner diameter (d) of not less than 20 μm and less than 30 μm and a head difference (h) of not more than 443 mm. When the inner diameter (d) is not less than 20 μm and less than 30 μm, by making the head difference (h) not more than 443 mm, expression (1) is satisfied, and the meniscus formed in the opening of nozzle 39 is maintained.

[0146] Region 213 is a region with an inner diameter (d) of not less than 30 μm and less than 50 μm and a head difference (h) of not more than 266 mm. When the inner diameter (d) is not less than 30 μm and less than 50 μm, by making the head difference (h) not more than 266 mm, expression (1) is satisfied, and the meniscus formed in the opening of nozzle 39 is maintained.

[0147] Region 214 is a region with an inner diameter (d) of not less than 50 μm and less than 80 μm and a head difference (h) of not more than 166 mm. When the inner diameter (d) is not less than 50 μm and less than 80 μm, by making the head difference (h) not more than 166 mm, expression (1) is satisfied, and the meniscus formed in the opening of nozzle 39 is maintained.

[0148] Region 215 is a region with an inner diameter (d) of not less than 80 μm and less than 90 μm and a head difference (h) of not more than 148 mm. When the inner diameter (d) is not less than 80 μm and less than 90 μm, by making the head difference (h) not more than 148 mm, expression (1) is satisfied, and the meniscus formed in the opening of nozzle 39 is maintained.

[0149] Region 216 is a region with an inner diameter (d) of not less than 90 μm and less than 100 μm and a head difference (h) of not more than 133 mm. When the inner diameter (d) is not less than 90 μm and less than 100 μm, expression (1) is satisfied by keeping the head difference (h) of not more than 133 mm, and the meniscus formed in the opening of nozzle 39 is maintained.

[0150] Region 217 is a region with an inner diameter (d) of not less than 100 μm and less than 110 μm and a head difference (h) of not more than 121 mm. When the inner diameter (d) is not less than 100 μm and less than 110 μm, expression (1) is satisfied by keeping the head difference (h) of not more than 121 mm, and the meniscus formed in the opening of nozzle 39 is maintained.

[0151] Region 218 is a region with an inner diameter (d) of not less than 110 μm and less than 120 μm and a head difference (h) of not more than 111 mm. When the inner diameter (d) is not less than 110 μm and less than 120 μm, by making the head difference (h) not more than 111 mm, expression (1) is satisfied, and the meniscus formed in the opening of nozzle 39 is maintained.

[0152] Figure 8BThe region 221 depicted is a region with an inner diameter (d) of not less than 1 μm and less than 133 μm and a head difference (h) of not more than 100 mm. When the head difference (h) is not more than 100 mm, by making the inner diameter (d) not less than 1 μm and less than 133 μm, expression (1) is satisfied, and the meniscus formed in the opening of the nozzle 39 is maintained.

[0153] Region 222 is a region with an inner diameter (d) of not less than 1 μm and less than 66 μm and a head difference (h) of greater than 100 mm and not more than 200 mm. When the head difference (h) is greater than 100 mm and not more than 200 mm, by making the inner diameter (d) not less than 1 μm and less than 66 μm, expression (1) is satisfied, and the meniscus formed in the opening of nozzle 39 is maintained.

[0154] Region 223 is a region with an inner diameter (d) of not less than 1 μm and less than 33 μm and a head difference (h) of greater than 200 mm and not more than 400 mm. When the head difference (h) is greater than 200 mm and not more than 400 mm, by making the inner diameter (d) not less than 1 μm and less than 33 μm, expression (1) is satisfied, and the meniscus formed in the opening of nozzle 39 is maintained.

[0155] Region 224 is a region with an inner diameter (d) of not less than 1 μm and less than 22 μm and a head difference (h) of greater than 400 mm and not more than 600 mm. When the head difference (h) is greater than 400 mm and not more than 600 mm, by ensuring that the inner diameter (d) is not less than 1 μm and less than 22 μm, expression (1) is satisfied, and the meniscus formed in the opening of nozzle 39 is maintained. Note that the reason for ensuring that the inner diameter (d) of nozzle 39 is not less than 1 μm is that if the inner diameter (d) is less than 1 μm, ink clogging may frequently occur.

[0156] When the second condition is met in the multifunctional peripheral device 10, the conditions for maintaining the meniscus formed in the opening of the nozzle 39 are as follows: Specifically, when the inner diameter (d) is not less than 5 μm and less than 20 μm, the head difference (h) is required to be no more than 290 mm; when the inner diameter (d) is not less than 20 μm and less than 30 μm, the head difference (h) is required to be no more than 193 mm; when the inner diameter (d) is not less than 30 μm and less than 50 μm, the head difference (h) is required to be no more than 116 mm; when the inner diameter (d) is not less than 50 μm and less than 80 μm, the head difference (h) is required to be no more than 73 mm; When the inner diameter (d) is not less than 80μm and less than 90μm, the head difference (h) is required to be no more than 64mm; when the inner diameter (d) is not less than 90μm and less than 100μm, the head difference (h) is required to be no more than 58mm; when the inner diameter (d) is not less than 100μm and less than 110μm, the head difference (h) is required to be no more than 53mm; and when the inner diameter (d) is not less than 110μm and less than 120μm, the head difference (h) is required to be no more than 48mm.

[0157] When the second condition is met in the multifunctional peripheral device 10, the conditions for maintaining the meniscus formed in the opening of the nozzle 39 are as follows: When the head difference (h) does not exceed 100 mm, the inner diameter (d) is required to be not less than 1 μm and less than 58 μm; when the head difference (h) is greater than 100 mm but not more than 200 mm, the inner diameter (d) is required to be not less than 1 μm and less than 29 μm; when the head difference (h) is greater than 200 mm but not more than 400 mm, the inner diameter (d) is required to be not less than 1 μm and less than 14 μm; and when the head difference (h) is greater than 400 mm but not more than 600 mm, the inner diameter (d) is required to be not less than 1 μm and less than 9 μm.

[0158] In the multi-functional peripheral device 10, the specific gravity (ρ) of the ink is not less than 1.03 g / cm³. 3 And not exceeding 1.13 g / cm 3 When the surface tension (σ) of the ink is not less than 25 mN / m and not more than 37 mN / m and the contact angle θ between the inner surface of the nozzle and the ink is not less than 25° and not more than 50°, in a manner similar to that in the case where the second condition is met in the multi-functional peripheral device 10, the expression (1) is satisfied by determining the head difference (h) based on the inner diameter (d) or by determining the inner diameter (d) based on the head difference (h), and the meniscus formed in the opening of the nozzle 39 is maintained.

[0159] [Effects of the Example]

[0160] According to this embodiment, since the inner diameter (d) and head difference (h) of the nozzle 39 satisfy expression (1), the surface tension F2 acting upward on the ink near the opening of the nozzle 39 is not less than the gravity F1 acting downward on the ink near the opening of the nozzle 39. Therefore, the meniscus of the nozzle 39 can be maintained when the gas layer of the reservoir 80 is in communication with the outside.

[0161] [Variation]

[0162] In the above embodiment, the inner diameter (d) and head difference (h) of the nozzle 39 are determined under the condition that the maximum storable amount corresponds to the amount when the liquid surface LS of the ink 90 is coplanar with the upper end of the atmospheric open port 88. However, there are no limitations on this. The maximum storable amount can be set to any amount that is not greater than the amount when the liquid surface LS of the ink 90 is coplanar with the upper end of the atmospheric open port 88.

[0163] For example, if any marking (e.g., line drawing, raised area, etc.) is formed (e.g., on the sidewall 80s of the reservoir 80), the maximum storable amount can be set to an amount that is not greater than the amount when the liquid surface LS of the ink 90 is coplanar with the upper end of the atmospheric open port 88 and not less than the amount when the liquid surface LS of the ink 90 is at the height of the marking. In this case, the maximum storable amount is based on the set maximum storable amount and the maximum liquid surface LS corresponding to the set maximum storable amount. max The position is used to determine the inner diameter (d) and head difference (h) of nozzle 39.

[0164] A mark can be formed to indicate to the user of the multifunction peripheral device 10 the height of the ink surface corresponding to the indicated maximum storage capacity. Note that the indicated maximum storage capacity is different from the maximum storage capacity used to determine the inner diameter (d), etc. For fail-safe designs, the indicated maximum storage capacity can be less than the maximum storage capacity, and the mark can be formed on the maximum liquid surface LS above the maximum storage capacity. max At a low altitude.

[0165] In the above embodiment, although only one memory 80 is provided on the recording section 24, it is permissible to provide multiple memory 80s on the recording section 24. For example, such as Figure 9 As depicted, the recording section 24 may be equipped with four storage devices 80C, 80M, 80Y and 80B.

[0166] Cyan ink (not shown in the figure) is stored in reservoir 80C. Magenta ink (not shown in the figure) is stored in reservoir 80M. Yellow ink (not shown in the figure) is stored in reservoir 80Y. Black ink (not shown in the figure) is stored in reservoir 80B. Reservoirs 80C, 80M, 80Y, and 80B are arranged side by side in the left-right direction 9. An atmospheric open port 88 is provided on each of reservoirs 80C, 80M, 80Y, and 80B. Note that reservoirs 80C, 80M, 80Y, and 80B can be arranged side by side in a direction different from the left-right direction 9, for example, in the front-back direction 8. Furthermore, the order in which reservoirs 80C, 80M, 80Y, and 80B are arranged is not limited to this. Figure 9 The order described in the document. Furthermore, the sizes of the individual storage units 80C, 80M, 80Y, and 80B may be the same or different from each other.

[0167] In the above embodiments, the system for the head 38 to record images on the sheet 12 is a serial head type, in which the head 38 records images on the sheet 12 while being moved by the carriage 40. However, it is permissible for the system for the head 38 to record images on the sheet 12 to be a line head type, in which the recording section 24 is not provided with the carriage 40, and the head 38 records images on the sheet 12 without moving. In the case of the line head type, the head 38 is configured to span from the right end to the left end of the media passage area. Furthermore, the transport operation and the printing operation are performed in parallel and continuously. That is, while transporting the sheet 12, ink droplets are continuously ejected from the nozzle 39. Furthermore, in the case of the line head type, the head 38 is supported by the frame of the housing 14.

[0168] In this embodiment, the reservoir 80 is mounted in the carriage 40 and replenished by pouring ink from the inlet port 83. However, the reservoir 80 is not limited to this configuration. For example, the reservoir 80 may be a cartridge that is attachable and removable relative to the carriage 40. In this case, if the amount of ink stored in the cartridge decreases, or if the ink runs out, the cartridge is replaced with a new one.

[0169] In this embodiment, although the reservoir 80 is supported by the carriage 40, it is permissible for the reservoir 80 not to be supported by the carriage 40. For example, as Figure 10As depicted, the reservoir 80 can be arranged in a different location from the carriage 40 within the multi-functional peripheral device 10. In this case, the reservoir 80 and the head 38 are connected to each other via a pipe 151 (an example of a "liquid channel"); ink 90 stored in the reservoir 80 is supplied to the head 38 via the pipe 151, etc. Also in this case, at least a portion of the reservoir 80 is located above the head 38. In this variation, while the head 38 is mounted on the carriage 40, the carriage 40 moves, the reservoir 80 is not mounted on the carriage 40, and the reservoir 80 and the head 38 are connected to each other via the pipe 151, etc.

[0170] In this embodiment, although an atmospheric-only open port 88 is provided on the upper wall 82 of the reservoir 80, as Figure 11A and Figure 11B As depicted, it is permissible to further provide an atmospheric communication channel 161 (an example of a "gas channel") on the upper wall 82 of the reservoir 80, which is continuous with the atmospheric open port 88.

[0171] exist Figure 11A In the example depicted, the atmospheric communication channel 161 is formed as a groove in the upper wall 82 of the reservoir 80, and the upper side of the atmospheric communication channel 161 is closed by a membrane 162. One end of the atmospheric communication channel 161 communicates with the gas layer of the reservoir 80 via an opening 163. The other end of the atmospheric communication channel 161 communicates with the outside via an atmospheric opening port 88 formed in the upper wall 82. The atmospheric communication channel 161 has a labyrinth structure 164 that repeats U-shaped turns in the front-rear direction 8 while extending along the left-right direction 9.

[0172] exist Figure 11B In the example depicted, a semi-permeable membrane 165, which closes the atmospheric open port 88, is attached to the atmospheric open port 88, which communicates with the other end of the atmospheric communication channel 161. The semi-permeable membrane 165 is a porous membrane having tiny pores that block the passage of ink while allowing the passage of gas. For example, the semi-permeable membrane 165 is formed of a fluorinated resin (fluororesin) such as polytetrafluoroethylene, polychlorotrifluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-ethylene copolymer, etc. Thus, the ink 90 stored in the internal space 81 of the reservoir 80 is blocked by the semi-permeable membrane 165 and therefore does not flow out to the outside of the reservoir 80 via the atmospheric communication channel 161 and the atmospheric open port 88. On the other hand, air can move freely between the gas layer of the reservoir 80 and the outside.

[0173] The atmospheric communication channel 161 may have the following structure: it has a semi-permeable membrane 165 that blocks the atmospheric opening port 88, but does not have a labyrinth structure 164. As described above, the atmospheric communication channel 161 may be configured to have at least one of the labyrinth structure 164 and the semi-permeable membrane 165.

[0174] In this embodiment, although no valve unit is provided on the atmospheric open port 88, it is permissible to provide a valve unit on the atmospheric open port 88. The valve unit is configured to switch the gas layer and the outside of the reservoir 80 between an open state and a blocked state. In this variant, when the inner diameter (d) and head difference (h) of the nozzle 39 are determined to satisfy expression (1), the meniscus formed in the opening of the nozzle 39 is maintained when the valve unit is in the open state.

Claims

1. A liquid discharge device, comprising: A head having a nozzle configured to discharge liquid; A reservoir configured to store the liquid, such that the liquid has a liquid surface, and such that, with the reservoir storing a maximum storable amount of the liquid, the liquid surface is positioned above the opening of the nozzle, the maximum storable amount being the maximum amount of the liquid that can be stored in the reservoir. and An atmospheric port connects the gas layer of the reservoir to the outside of the reservoir, the gas layer being located within the reservoir and above the liquid surface. The inner diameter d and head difference h of the nozzle satisfy the expression ρhd / σcosθ≤4 / g, where ρ is the specific gravity of the liquid, σ is the surface tension of the liquid, θ is the contact angle of the liquid in the nozzle, and g is the acceleration due to gravity. The head difference h is the height difference between the meniscus formed in the opening of the nozzle and the upper end of the atmospheric port.

2. The liquid discharge device according to claim 1, wherein the inner diameter d is not less than 5 μm, and the inner diameter d is less than 20 μm; and The head difference h does not exceed 664 mm.

3. The liquid discharge device according to claim 1, wherein the inner diameter d is not less than 20 μm, and the inner diameter d is less than 30 μm; and The head difference h does not exceed 443mm.

4. The liquid discharge device according to claim 1, wherein the inner diameter d is not less than 30 μm, and the inner diameter d is less than 50 μm; and The head difference h does not exceed 266mm.

5. The liquid discharge device according to claim 1, wherein the inner diameter d is not less than 50 μm, and the inner diameter d is less than 80 μm; and The head difference h does not exceed 166mm.

6. The liquid discharge device according to claim 1, wherein the inner diameter d is not less than 80 μm and the inner diameter d is less than 90 μm; and The head difference h does not exceed 148mm.

7. The liquid discharge device according to claim 1, wherein the inner diameter d is not less than 90 μm, and the inner diameter d is less than 100 μm; and The head difference h does not exceed 133mm.

8. The liquid discharge device according to claim 1, wherein the inner diameter d is not less than 100 μm, and the inner diameter d is less than 110 μm; and The head difference h does not exceed 121mm.

9. The liquid discharge device according to claim 1, wherein the inner diameter d is not less than 110 μm and the inner diameter d is less than 120 μm; and The head difference h does not exceed 111 mm.

10. The liquid discharge device according to claim 1, wherein the inner diameter d is not less than 1 μm, and the inner diameter d is less than 133 μm; and The head difference h does not exceed 100mm.

11. The liquid discharge device according to claim 1, wherein the inner diameter d is not less than 1 μm, and the inner diameter d is less than 66 μm; and The head difference h is greater than 100mm and the head difference h does not exceed 200mm.

12. The liquid discharge device according to claim 1, wherein the inner diameter d is not less than 1 μm, and the inner diameter d is less than 33 μm; and The head difference h is greater than 200mm and the head difference h does not exceed 400mm.

13. The liquid discharge device according to claim 1, wherein the inner diameter d is not less than 1 μm, and the inner diameter d is less than 22 μm; and The head difference h is greater than 400mm and the head difference h does not exceed 600mm.

14. The liquid discharge device according to any one of claims 1 to 13, wherein the viscosity of the liquid is not less than 2 cps and the viscosity of the liquid is less than 11 cps.

15. The liquid discharge device according to any one of claims 1 to 13, further comprising a carriage configured to move with the head and the reservoir mounted on the carriage.

16. The liquid discharge device according to any one of claims 1 to 13, further comprising a carriage configured to move with the head mounted on the carriage. The storage container is not mounted on the carriage; and The reservoir and the head are connected by a liquid channel.

17. The liquid discharge device of claim 15, wherein the carriage is configured to move in the scanning direction; and The head is configured to discharge the liquid while the carriage is moving in the scanning direction.

18. The liquid discharge device according to any one of claims 1 to 13, further comprising a gas passage continuous with the atmospheric port. The gas channel has at least one of a labyrinth structure and a semi-permeable membrane.

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