Liquid dispensing device

Abstract

To provide a liquid dispensing device that can suppress the deterioration of print quality. [Solution] The system comprises a liquid discharge unit 12 that discharges a settling first liquid and prints it onto a medium 20, a first supply unit 15, and a control unit 18. The first supply unit 15 has a first supply channel 35, a branch channel 36, a liquid delivery unit 37 located in the branch channel 36, and a first pressure regulating valve 38 provided in the first supply channel 35 between the confluence position P2 and the liquid discharge unit 12. The first pressure regulating valve 38 closes the first supply channel 35 when the negative pressure downstream of the first pressure regulating valve 38 is less than a predetermined negative pressure, and opens the first supply channel 35 when the negative pressure downstream of the first pressure regulating valve 38 is equal to or greater than the predetermined negative pressure. The control unit 18 drives the liquid delivery unit 37 to cause the liquid to flow in the branch channel 36 from the confluence position P2 to the branch position P1, thereby circulating the liquid in the first supply channel 35 and the branch channel 36, which is performed during the printing operation in which the liquid discharge unit 12 prints onto the medium 20.

Description

Technical Field

[0001] The present invention relates to a liquid ejection device such as a printer.

Background Art

[0002] For example, as in Patent Document 1, there is a printer which is an example of a liquid ejection device that ejects ink, which is an example of a liquid, from a liquid ejection head which is an example of a liquid ejection unit to perform printing. The printer includes an ink supply tube which is an example of a supply flow path, a circulation tube which is an example of a branch flow path, a circulation pump which is an example of a liquid feeding unit, and a maintenance mechanism. The ink supply tube supplies ink from an ink cartridge which is an example of a liquid storage unit to the liquid ejection head. The circulation tube forms a circulation flow path with the ink supply tube.

[0003] The ink may have pigment particles settle in the ink supply tube to form deposits. The printer drives the circulation pump to circulate the ink, thereby stirring the ink and discharging the ink in the supply tube that cannot be stirred to the maintenance mechanism.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Sedimentation of the liquid also occurs during printing. Therefore, if the printing time is long, there is a risk that the sedimented liquid will be ejected and affect the print quality. However, if printing is interrupted and circulated, there is a risk that the color tone will change between the part printed before the interruption and the part printed after the interruption.

Means for Solving the Problems

[0006] A liquid dispensing device that solves the above problems comprises a liquid dispensing unit that dispenses a settling liquid and prints it onto a medium, a supply unit that supplies liquid from a liquid storage unit to the liquid dispensing unit, and a control unit. The supply unit comprises a supply channel connecting the liquid storage unit and the liquid dispensing unit, a branch channel that branches off from the supply channel at a branching position and merges with the supply channel at a confluence position downstream of the branching position, a liquid delivery unit located in the branch channel, and a pressure regulating valve provided in the supply channel between the confluence position and the liquid dispensing unit. The pressure regulating valve closes the supply channel when the negative pressure downstream of the pressure regulating valve is less than a predetermined negative pressure, and opens the supply channel when the negative pressure downstream of the pressure regulating valve is equal to or greater than the predetermined negative pressure. The control unit drives the liquid delivery unit to cause liquid to flow in the branch channel from the confluence position to the branching position, thereby circulating the liquid in the supply channel and the branch channel during the printing operation in which the liquid dispensing unit prints onto the medium. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic diagram of one embodiment of a liquid dispensing device. [Modes for carrying out the invention]

[0008] [Embodiment] Hereinafter, one embodiment of the liquid dispensing device will be described with reference to the drawings. The liquid dispensing device is an inkjet printer that prints by dispensing ink, which is an example of a liquid, onto a medium such as paper, fabric, vinyl sheet, plastic parts, or metal parts.

[0009] <Liquid discharge device> As shown in Figure 1, the liquid dispensing device 11 may include a liquid dispensing unit 12, a transport unit 13, a mounting unit 14, a first supply unit 15 (an example of a supply unit), a second supply unit 16, a notification unit 17, and a control unit 18.

[0010] <Liquid discharge part> The liquid dispensing unit 12 dispensing liquid to print on the medium 20. The liquid dispensing unit 12 prints on the medium 20 which is transported by the transport unit 13. The liquid dispensing unit 12 has a plurality of nozzles 21. The liquid dispensing unit 12 is configured to dispense liquid from a plurality of nozzles 21. The liquid dispensing unit 12 may dispense multiple types of liquids. The liquid dispensing unit 12 may dispense a first liquid and a second liquid, which are examples of liquids. The first liquid is a settling liquid. The first liquid may settle due to stagnation, causing its components to settle. The second liquid is less likely to settle than the first liquid.

[0011] <Conveying Section> The transport unit 13 may transport the medium 20 unwound from the roll body 23. The roll body 23 is the unprinted medium 20 wound into a roll. The transport unit 13 transports the long medium 20. The transport unit 13 may include a feed shaft 24, a support unit 25, a drive roller 26, a driven roller 27, and a winding shaft 28.

[0012] The dispensing shaft 24 rotatably supports the roll body 23. The dispensing shaft 24 dispenses the medium 20 by rotating the roll body 23. The support portion 25 is configured to support the medium 20.

[0013] The conveying unit 13 may include a plurality of drive rollers 26 and a plurality of driven rollers 27. The drive rollers 26 convey the medium 20 by rotating with the medium 20 sandwiched between them and the driven rollers 27. The driven rollers 27 rotate in response to the conveyance of the medium 20.

[0014] The winding shaft 28 winds up the printed medium 20. The winding shaft 28 rotatably supports the medium 20 wound in a roll. The winding shaft 28 pulls the medium 20 towards it by rotating the rolled medium 20.

[0015] <Mounting part> A liquid storage section 30 is detachably mounted on the mounting section 14. The liquid storage section 30 may be a replaceable cartridge. Multiple liquid storage sections 30 may be mounted on the mounting section 14. In this embodiment, a first liquid storage section 31 and a second liquid storage section 32 can be mounted on the mounting section 14. The liquid dispensing device 11 may separately include a mounting section 14 to which the first liquid storage section 31 is mounted and a mounting section 14 to which the second liquid storage section 32 is mounted. The first liquid storage section 31 contains the first liquid. The second liquid storage section 32 contains the second liquid.

[0016] <1st supply section> The first supply unit 15 supplies the first liquid from the first liquid storage unit 31 to the liquid discharge unit 12. The first supply unit 15 may also include a first supply pump 34, a first supply channel 35 which is an example of a supply channel, a branch channel 36, a liquid delivery unit 37, and a first pressure regulating valve 38 which is an example of a pressure regulating valve.

[0017] The first supply pump 34 is located in the first supply channel 35. The first supply pump 34 may supply the first liquid under pressure in the supply direction D1. The upstream end of the first supply channel 35 may be provided on the mounting section 14. The upstream end of the first supply channel 35 may be, for example, a hollow needle that pierces the first liquid storage section 31. By connecting the upstream end of the first supply channel 35 to the first liquid storage section 31 mounted on the mounting section 14, the first liquid stored in the first liquid storage section 31 can be discharged. The downstream end of the first supply channel 35 is connected to the liquid discharge section 12. The first supply channel 35 connects the first liquid storage section 31 and the liquid discharge section 12.

[0018] The branch flow path 36 is a flow path through which the first liquid flows. The branch flow path 36 branches from the first supply flow path 35. Specifically, the branch flow path 36 branches at the branch position P1 in the first supply flow path 35. After branching from the first supply flow path 35, the branch flow path 36 merges with the first supply flow path 35. Specifically, the branch flow path 36 merges at the merge position P2 in the first supply flow path 35. Both ends of the branch flow path 36 are connected to the first supply flow path 35. The merge position P2 is a position downstream of the branch position P1 in the first supply flow path 35. The branch flow path 36 forms a circulation flow path 40 together with the first supply flow path 35. Specifically, the first supply flow path 35 and the branch flow path 36 between the branch position P1 and the merge position P2 constitute the circulation flow path 40.

[0019] The liquid delivery unit 37 is located in the branch flow path 36. The liquid delivery unit 37 is a pump that causes the first liquid to flow in the branch flow path 36. The liquid delivery unit 37 causes the first liquid to flow in the circulation direction D2 from the merge position P2 toward the branch position P1 in the branch flow path 36.

[0020] The first pressure regulating valve 38 is provided in the first supply flow path 35 between the merge position P2 and the liquid discharge unit 12. The first pressure regulating valve 38 closes the first supply flow path 35 when the negative pressure downstream of the first pressure regulating valve 38 is less than a predetermined negative pressure. The first pressure regulating valve 38 opens the first supply flow path 35 when the negative pressure downstream of the first pressure regulating valve 38 becomes equal to or greater than the predetermined negative pressure. The predetermined negative pressure is the pressure at which a concave liquid surface is formed at the nozzle 21 with respect to the direction in which the first liquid is discharged from the nozzle 21. The first pressure regulating valve 38 stabilizes the pressure of the first liquid supplied to the nozzle 21 by adjusting the pressure of the first liquid supplied under pressure.

[0021] <Second Supply Unit> The second supply unit 16 supplies the second liquid from the second liquid storage unit 32 to the liquid discharge unit 12. The second supply unit 16 includes a second supply pump 42, a second supply flow path 43, and a second pressure regulating valve 44.

[0022] The second supply pump 42 is located in the second supply flow path 43. The second supply pump 42 may pressurize and supply the second liquid in the supply direction D1. The second supply channel 43 may have its upstream end provided at the mounting portion 14. The upstream end of the second supply channel 43 may be, for example, a hollow needle that pierces the second liquid storage portion 32. When the upstream end of the second supply channel 43 is connected to the second liquid storage portion 32 mounted on the mounting portion 14, the second liquid stored in the second liquid storage portion 32 can be led out. The downstream end of the second supply channel 43 is connected to the liquid ejection portion 12. The second supply channel 43 connects the second liquid storage portion 32 and the liquid ejection portion 12.

[0023] The second pressure regulating valve 44 is provided in the second supply channel 43. When the negative pressure downstream of the second pressure regulating valve 44 is less than a predetermined negative pressure, the second pressure regulating valve 44 closes the second supply channel 43. When the negative pressure downstream of the second pressure regulating valve 44 becomes equal to or greater than the predetermined negative pressure, the second pressure regulating valve 44 opens the second supply channel 43. The predetermined negative pressure is the pressure at which a concave liquid surface is formed at the nozzle 21 in the direction of ejecting the second liquid from the nozzle 21. The second pressure regulating valve 44 stabilizes the pressure of the second liquid supplied to the nozzle 21 by adjusting the pressure of the second liquid supplied under pressure.

[0024] <Notification unit> The notification unit 17 can, for example, notify a user of information. The notification unit 17 may be a monitor that notifies by displaying an image, characters, etc., or may be a touch panel that enables display and operation. The notification unit 17 may be a speaker that notifies by emitting sound, voice, etc., or may be a bell. The notification unit 17 may be a light that notifies by emitting light, blinking, etc. The notification unit 17 may be a communication unit that communicates with an external device such as a smartphone, a personal computer, a server, etc. and causes the external device to notify information.

[0025] <Control unit> The control unit 18 comprehensively controls the driving of each mechanism in the liquid ejection device 11 and controls various operations executed by the liquid ejection device 11.

[0026] The control unit 18 may be configured as a circuit including α: one or more processors that perform various processes according to a computer program, β: one or more dedicated hardware circuits that perform at least some of the various processes, or γ: a combination thereof. The hardware circuit is, for example, an application-specific integrated circuit. The processor includes a CPU and memory such as RAM and ROM, and the memory stores program code or instructions configured to cause the CPU to perform the processes. Memory, or computer-readable media, includes any readable media that can be accessed by a general-purpose or dedicated computer.

[0027] The control unit 18 is capable of performing printing and circulation operations. The printing operation is the operation in which the liquid discharge unit 12 prints onto the medium 20. The circulation operation is the operation in which the first liquid is circulated in the circulation direction D2 in the circulation channel 40. The control unit 18 performs the circulation operation by driving the liquid delivery unit 37. The circulation operation circulates the first liquid in the first supply channel 35 and the branch channel 36 by causing the first liquid to flow from the confluence position P2 to the branch position P1 in the branch channel 36. The first liquid is agitated by circulating in the circulation channel 40. The control unit 18 performs the circulation operation to prevent and eliminate sedimentation of the first liquid.

[0028] <Operation of this embodiment> The operation of this embodiment will now be described. The control unit 18 may cause the liquid supply unit 37 to perform a periodic circulation operation. If the timing for performing the circulation operation is during a printing operation, the control unit 18 will perform the circulation operation without interrupting the printing operation. In other words, the control unit 18 will perform the circulation operation during the printing operation.

[0029] In this embodiment, the circulation operation performed during printing is also called simultaneous circulation, and the circulation operation performed when printing is not being performed is also called standalone circulation. The control unit 18 may set the pressure at which the liquid supply unit 37 sends the first liquid during simultaneous circulation to be lower than the pressure at which the liquid supply unit 37 sends the first liquid during standalone circulation.

[0030] The control unit 18 may instruct the notification unit 17 to notify it that it will perform a cyclic operation. The control unit 18 may perform the cyclic operation after being notified. If the timing for performing a cyclic operation occurs during a printing operation, the control unit 18 may instruct the notification unit 17 to notify it that it will perform a cyclic operation during a printing operation before performing the printing operation.

[0031] <Effects of this embodiment> The effects of this embodiment will now be explained. (1-1) The first pressure regulating valve 38 opens and closes the first supply channel 35 in accordance with the pressure of the first liquid downstream. Therefore, even if the first liquid is circulated upstream of the first pressure regulating valve 38, pressure fluctuations associated with the circulation of the first liquid do not easily affect the downstream side of the first pressure regulating valve 38. The control unit 18 performs a circulation operation during the printing operation. By performing a circulation operation, the first liquid can be stirred, thereby reducing the risk of the first liquid that has settled being supplied to the liquid discharge unit 12. Therefore, a decrease in print quality can be suppressed.

[0032] (1-2) The liquid discharge unit 12 prints on a long medium 20 unwound from the roll body 23. When printing on a long medium 20, the printing time may be long. However, by performing a circulation operation during the printing operation, even when the printing time is long, the risk of the first liquid that has settled is supplied to the liquid discharge unit 12 can be reduced.

[0033] (1-3) The second supply unit 16 supplies the second liquid to the liquid discharge unit 12. The second liquid is less likely to settle than the first liquid. In other words, by not providing the branching channel 36 and the liquid delivery unit 37 in the second supply unit 16 which supplies the second liquid which is less likely to settle, the liquid discharge device 11 can be made smaller.

[0034] (1-4) The control unit 18 periodically performs a circulation operation. Therefore, the control load can be reduced compared to, for example, the case where the circulation operation is performed in accordance with the degree of sedimentation of the first liquid.

[0035] (1-5) The liquid storage section 30 is mounted on the mounting section 14. By mounting the liquid storage section 30, the liquid storage section 30 can be easily connected to the first supply channel 35 and the second supply channel 43.

[0036] (1-6) The control unit 18 can perform circulation operations during printing and when printing is not being performed. During circulation operations during printing, the pressure at which the liquid supply unit 37 sends the first liquid can be reduced, thereby reducing pressure fluctuations of the first liquid sent to the liquid discharge unit 12 even if the first pressure regulating valve 38 opens the first supply passage 35 during circulation operations. During circulation operations performed when printing is not being performed, the pressure at which the liquid supply unit 37 sends the first liquid can be increased, thereby shortening the time required to agitate the first liquid.

[0037] (1-7) The control unit 18 notifies the user that it is performing a cyclic operation. This allows the user to be informed that if the print quality does not meet the required level, the cause may be a cyclic operation.

[0038] (1-8) The control unit 18 notifies the notification unit 17 that it will perform a cyclic operation during the printing operation before the printing operation is performed. Therefore, the user can choose whether to perform the cyclic operation before the printing operation is performed, or to start the printing operation immediately.

[0039] [Example of changes] This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0040] The first supply unit 15 may be configured without a first supply pump 34. The first supply unit 15 may supply the first liquid from the first liquid storage unit 31 to the liquid discharge unit 12 by water head. The second supply unit 16 may be configured without a second supply pump 42. The second supply unit 16 may supply the second liquid from the second liquid storage unit 32 to the liquid discharge unit 12 by water head.

[0041] The control unit 18 may, when it is time to perform a cyclic operation during the printing operation, notify the user that a cyclic operation will be performed during the printing operation. The control unit 18 may also notify the notification unit 17 that it has performed a cyclic operation during the printing operation, or after the cyclic operation has been performed.

[0042] The control unit 18 may set the pressure at which the liquid delivery unit 37 delivers the first liquid to be the same in both simultaneous circulation operation and independent circulation operation. The control unit 18 may also set the pressure at which the liquid delivery unit 37 delivers the first liquid in simultaneous circulation operation to be greater than the pressure at which the liquid delivery unit 37 delivers the first liquid in independent circulation operation.

[0043] The liquid storage section 30 may be a tank fixed to the mounting section 14. The liquid storage section 30 may be refillable. The control unit 18 may perform a circulation operation at a timing specified by the user. The control unit 18 may also perform a circulation operation at a timing corresponding to printing conditions such as printing frequency and amount of liquid used, and liquid conditions such as the color of the liquid and the contents of the liquid.

[0044] The liquid dispensing device 11 may be a device that dispenses one type of liquid to perform monochrome printing. In this case, the liquid dispensing unit 12 may be configured without a second supply unit 16. The liquid dispensing device 11 may include a plurality of first supply units 15. Each of the plurality of first supply units 15 may supply a plurality of types of first liquids that have settling properties. The plurality of first supply units 15 may supply at least one type of first liquid and at least one type of second liquid to the liquid dispensing unit 12.

[0045] The liquid dispensing device 11 may print on short-length media 20 such as standard paper, postcards, business cards, cards, and envelopes. The liquid dispensing device 11 may be a liquid dispensing device that sprays or dispenses liquids other than ink. The state of the liquid dispensed from the liquid dispensing device as minute droplets may include granular, teardrop-shaped, or thread-like forms. The liquid referred to here may be any material that can be dispensed from the liquid dispensing device. For example, the liquid may be any state in which a substance is in the liquid phase, and may include highly or low viscosity liquids, sols, gel water, other inorganic solvents, organic solvents, solutions, liquid resins, liquid metals, and other fluids. The liquid may include not only liquids as a state of matter, but also functional material particles consisting of solids such as pigments and metal particles dissolved, dispersed, or mixed in a solvent. Typical examples of liquids include inks and liquid crystals as described in the above embodiments. Here, ink refers to general water-based inks and oil-based inks, as well as various liquid compositions such as gel inks and hot-melt inks. Specific examples of liquid dispensing devices include devices that dispense liquids containing materials such as electrode materials and colorants in the form of dispersion or dissolution, used in the manufacture of liquid crystal displays, electroluminescent displays, surface-emitting displays, and color filters. Liquid dispensing devices may also be devices that dispense bio-organic substances used in biochip manufacturing, devices that dispense liquid samples used as precision pipettes, printing devices, microdispensers, etc. Liquid dispensing devices may also be devices that dispense lubricating oil to precision machinery such as watches and cameras with pinpoint accuracy, or devices that dispense transparent resin liquids such as ultraviolet-curing resins onto substrates to form minute hemispherical lenses, optical lenses, etc. used in optical communication elements. Liquid dispensing devices may also be devices that dispense etching solutions such as acids or alkalis to etch substrates.

[0046] [Definition] As used herein, the expression "at least one" means "one or more" of the desired options. For example, as used herein, if there are two options, the expression "at least one" means "only one option" or "both of the two options." As another example, as used herein, the expression "at least one" means "only one option," "a combination of two arbitrary options," or "a combination of three or more arbitrary options" if there are three or more options.

[0047] [Note] The following describes the technical concepts and their effects that can be understood from the embodiments and modifications described above.

[0048] [1] The liquid dispensing device comprises a liquid dispensing unit that dispenses a settling liquid for printing on a medium, a supply unit that supplies liquid from a liquid storage unit to the liquid dispensing unit, and a control unit, wherein the supply unit has a supply channel connecting the liquid storage unit and the liquid dispensing unit, a branch channel that branches off from the supply channel at a branching position and merges with the supply channel at a merging position downstream of the branching position in the supply channel, a liquid delivery unit located in the branch channel, and a pressure regulating valve provided in the supply channel between the merging position and the liquid dispensing unit, wherein the pressure regulating valve closes the supply channel when the negative pressure downstream of the pressure regulating valve is less than a predetermined negative pressure, and opens the supply channel when the negative pressure downstream of the pressure regulating valve is equal to or greater than the predetermined negative pressure, and the control unit drives the liquid delivery unit to cause liquid to flow in the branch channel from the merging position to the branching position, thereby performing a circulation operation to circulate the liquid in the supply channel and the branch channel during the printing operation in which the liquid dispensing unit prints on a medium.

[0049] In this configuration, the pressure regulating valve opens and closes the supply channel in accordance with the pressure of the liquid downstream. Therefore, even if the liquid is circulated upstream of the pressure regulating valve, the pressure fluctuations associated with the circulation of the liquid are less likely to affect the downstream side. The control unit performs the circulation operation during the printing operation. By performing the circulation operation, the liquid can be agitated, which reduces the risk of sedimented liquid being supplied to the liquid discharge section. Therefore, a decrease in print quality can be suppressed.

[0050] [2] The liquid dispensing device described in [1] above includes a transport unit for transporting a medium unwound from a roll body, and the liquid dispensing unit may print on the medium transported by the transport unit. In this configuration, the liquid dispensing unit prints on a long medium unwound from a roll. When printing on a long medium, the printing time can be long. However, by performing a circulation operation during the printing process, the risk of sedimented liquid being supplied to the liquid dispensing unit can be reduced, even when the printing time is long.

[0051] [3] In the liquid discharge device described in [1] or [2] above, when the liquid storage section is referred to as the first liquid storage section, the supply section as the first supply section, the liquid stored in the first liquid storage section as the first liquid, the supply channel as the first supply channel, and the pressure regulating valve as the first pressure regulating valve, the device may be provided with a second supply section that supplies a second liquid, which is less likely to settle than the first liquid, from the second liquid storage section to the liquid discharge section, and the second supply section may have a second supply channel connecting the second liquid storage section and the liquid discharge section, and a second pressure regulating valve provided in the second supply channel.

[0052] In this configuration, the second supply unit supplies the second liquid to the liquid discharge unit. The second liquid is less likely to settle than the first liquid. In other words, by not providing a branching channel and a liquid delivery unit in the second supply unit that supplies the second liquid which is less likely to settle, the liquid discharge device can be made smaller.

[0053] [4] In any one of the liquid dispensing devices described in [1] to [3] above, the control unit may cause the liquid supply unit to periodically perform the circulation operation. With this configuration, the control unit periodically performs a circulation operation. Therefore, the control load can be reduced compared to, for example, a case where the circulation operation is performed in accordance with the degree of liquid sedimentation.

[0054] [5] Any one of the liquid dispensing devices described in [1] to [4] above may be equipped with a mounting section to which the liquid storage section is detachably attached. In this configuration, the liquid container is attached to the mounting section. By attaching the liquid container, it can be easily connected to the supply channel.

[0055] [6] In any one of the liquid dispensing devices described in [1] to [5] above, the control unit may reduce the pressure at which the liquid supply unit delivers liquid during the circulation operation performed during the printing operation to a lower pressure than the pressure at which the liquid supply unit delivers liquid during the circulation operation performed when the printing operation is not being performed.

[0056] With this configuration, the control unit can perform circulation operations both during and when printing is not being performed. During circulation operations while printing, the pressure at which the liquid supply unit sends the liquid can be reduced, thereby minimizing pressure fluctuations in the liquid sent to the liquid discharge unit even if the pressure regulating valve opens the supply passage during circulation. During circulation operations performed when printing is not being performed, the pressure at which the liquid supply unit sends the liquid can be increased, thereby shortening the time required for liquid agitation.

[0057] [7] In any one of the liquid dispensing devices described in [1] to [6] above, the control unit may cause the notification unit to notify it that it is performing the circulation operation. With this configuration, the control unit is notified when a cyclic operation is being performed. Therefore, if the print quality does not meet the required level, the user can be informed that the cause may be a cyclic operation.

[0058] [8] In the liquid dispensing device described in [4] above, if the timing for executing the circulation operation is to be performed during the printing operation, the control unit may have the notification unit notify the notification unit that the circulation operation will be performed during the printing operation before the printing operation is performed.

[0059] In this configuration, the control unit notifies the notification unit before the printing operation is performed that a cyclic operation will be performed during the printing operation. Therefore, the user can choose whether to perform the cyclic operation before the printing operation, or to start the printing operation immediately. [Explanation of symbols]

[0060] 11...Liquid discharge device, 12...Liquid discharge section, 13...Conveying section, 14...Mounting section, 15...First supply section, 16...Second supply section, 17...Notification section, 18...Control unit, 20...Media, 21...Nozzle, 23...Roll body, 24...Feeding shaft, 25...Support section, 26...Driven roller, 27...Driven roller, 28...Winding shaft, 30...Liquid storage section, 31...First liquid storage section, 32...Second liquid storage section, 34...First supply pump, 35...First supply channel, 36...Branching channel, 37...Liquid delivery section, 38...First pressure regulating valve, 40...Circulation channel, 42...Second supply pump, 43...Second supply channel, 44...Second pressure regulating valve, D1...Supply direction, D2...Circulation direction, P1...Branching position, P2...Merging position.

Claims

1. A liquid dispensing unit that dispenses a settling liquid and prints it onto a medium, A supply unit that supplies liquid from the liquid storage unit to the liquid discharge unit, Control unit and Equipped with, The aforementioned supply unit is A supply channel connecting the liquid storage section and the liquid discharge section, A branch channel that branches off from the supply channel at a branching point, wherein the branch channel merges with the supply channel at a merging point downstream of the branching point in the supply channel, The liquid delivery unit located in the aforementioned branched channel, A pressure regulating valve is provided in the supply channel between the confluence point and the liquid discharge section, It has, The pressure regulating valve closes the supply passage when the negative pressure downstream of the pressure regulating valve is less than a predetermined negative pressure, and opens the supply passage when the negative pressure downstream of the pressure regulating valve is equal to or greater than the predetermined negative pressure. A liquid dispensing device characterized in that the control unit drives the liquid supply unit and causes the liquid to flow in the branched channel from the confluence position to the branching position, thereby performing a circulation operation that circulates the liquid in the supply channel and the branched channel, while the liquid dispensing unit is performing a printing operation that prints on a medium.

2. It is equipped with a transport unit that transports the medium unwound from the roll, The liquid dispensing apparatus according to claim 1, characterized in that the liquid dispensing unit prints onto a medium conveyed by the conveying unit.

3. When the liquid storage section is referred to as the first liquid storage section, the supply section as the first supply section, the liquid stored in the first liquid storage section as the first liquid, the supply channel as the first supply channel, and the pressure regulating valve as the first pressure regulating valve, The system includes a second supply unit that supplies a second liquid, which is less likely to settle than the first liquid, from a second liquid storage unit to the liquid discharge unit. The second supply unit is, A second supply channel connecting the second liquid storage section and the liquid discharge section, A second pressure regulating valve is provided in the second supply channel, A liquid dispensing device according to claim 1, characterized by having the following features.

4. The liquid dispensing device according to claim 1, characterized in that the control unit causes the liquid supply unit to periodically perform the circulation operation.

5. The liquid dispensing device according to claim 1, characterized in that it comprises a mounting portion to which the liquid storage portion is detachably attached.

6. The liquid dispensing device according to claim 1, characterized in that the control unit reduces the pressure at which the liquid supply unit sends liquid during the circulation operation performed during the printing operation to a lower pressure at which the liquid supply unit sends liquid during the circulation operation performed when the printing operation is not being performed.

7. The liquid dispensing device according to any one of claims 1 to 6, characterized in that the control unit causes the notification unit to notify it that it is performing the circulation operation.

8. The liquid dispensing device according to claim 4, characterized in that when the timing for executing the circulation operation is to be performed during the printing operation, the control unit causes the notification unit to notify the notification unit that the circulation operation will be performed during the printing operation before the printing operation is performed.

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