JP2018202644A - Liquid discharge device and control method therefor - Google Patents

Abstract

To improve discharge control of liquid in a liquid discharge device.SOLUTION: A control part of a liquid discharge device executes: pressurizing processing for causing a volume change part to reduce a volume of a liquid chamber, increase a pressure of the liquid chamber and start outflow of liquid from nozzles in a state where transmission of a pressure from the liquid chamber to a flow passage is suppressed by a pressure transmission adjustment part; pressure-reduction processing for reducing the pressure of the liquid chamber and separating droplets from the liquid of the nozzles by driving at least one of the pressure transmission adjustment part and the volume change part when predetermined lapse time elapses during the outflow of the liquid from the nozzles; and discharge amount control processing for determining the lapse time according to a target discharge amount of the liquid before executing the pressure-reduction processing.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a liquid ejection apparatus and a control method thereof.

  Conventionally, various liquids that eject liquid such as ink stored in a liquid chamber from nozzles communicating with the liquid chamber by changing the volume of the liquid chamber by an actuator and changing the pressure in the liquid chamber A discharge device has been proposed (for example, Patent Document 1 below).

JP 2007-320042 A

  In such a liquid ejecting apparatus, it is desirable that the amount of liquid ejected can be controlled more accurately. In the ink jet apparatus disclosed in Patent Document 1, the ink ejection speed and the ejection amount are set and changed by a resistance variable mechanism that varies the fluid resistance in the supply channel according to the amount of insertion of the tip end into the supply channel. However, in the technique of Patent Document 1, sufficient consideration is not given to the control of the pressure in the liquid chamber when the liquid is discharged from the nozzle. Therefore, when liquid is ejected from the nozzle, the liquid ejected from the nozzle is not properly interrupted, the rear end portion extends, and there is a possibility that the shape of the liquid droplet may collapse, and the amount of liquid ejected. There was a possibility of errors. In addition, when the droplets are separated, unnecessary mist more than expected is generated, and the flying state of the droplets and the landing state of the droplets may be deteriorated. As described above, there is still room for improvement in the liquid discharge control in the liquid discharge apparatus.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms.

[1] One embodiment of the present invention is provided as a liquid ejection device. The liquid ejection apparatus includes: a liquid chamber that contains a liquid; and a flow path of the liquid connected to the liquid chamber, the flow path including at least an inflow path for supplying the liquid to the liquid chamber; A nozzle connected to the liquid chamber for discharging the liquid in the liquid chamber; a volume changing unit for changing the volume of the liquid chamber and discharging the liquid from the nozzle; and the flow path from the liquid chamber; Controlling the flow of the liquid into the pressure chamber and adjusting the pressure transmission from the liquid chamber to the flow path; and controlling the volume changing section and the pressure transmission adjusting section; And a controller that discharges the liquid from the nozzle. The control unit reduces the volume of the liquid chamber by causing the volume changing unit to reduce the volume of the liquid chamber in a state where transmission of pressure from the liquid chamber to the flow path is suppressed by the pressure transmission adjusting unit. A pressurizing process for increasing the pressure and starting the outflow of the liquid from the nozzle; and after the pressurizing process is performed, a predetermined elapsed time is passed while the liquid is flowing out of the nozzle. When the time has elapsed, a pressure reduction process is performed in which at least one of the pressure transmission adjustment unit and the volume changing unit is driven to reduce the pressure of the liquid chamber and separate and eject droplets from the liquid of the nozzle. And a discharge amount control process for determining the elapsed time according to the target discharge amount of the liquid before the decompression process.
According to the liquid ejection device of this aspect, in the pressurizing process, the pressure of the liquid chamber is increased in a state where the transmission of the pressure of the liquid chamber to the flow path is suppressed. Therefore, the driving force for starting the outflow of the liquid from the nozzle can be efficiently transmitted to the nozzle. Moreover, the liquid and droplet of the nozzle can be efficiently separated by the pressure change caused by the decompression process. For this reason, for example, the occurrence of defective ejection is suppressed such that the liquid droplets ejected from the nozzles are unnecessarily tailed or accompanied with unnecessary mist. Furthermore, by adjusting the elapsed time after the pressurization process is performed, the liquid discharge amount can be easily controlled with high accuracy. As described above, according to the liquid ejection apparatus of this aspect, it is possible to improve the controllability of the liquid ejection amount while suppressing the occurrence of defective liquid ejection, and to improve the liquid ejection control in the liquid ejection apparatus.

[2] In the liquid ejection device according to the above aspect, the pressure transmission adjusting unit adjusts inflow of the liquid from the liquid chamber to the inflow path by changing a flow path resistance of the inflow path. The pressurizing process is performed in a state in which the flow resistance of the inflow path is increased by the inflow path resistance change section and the transmission of pressure from the liquid chamber to the inflow path is suppressed. The decompression process is performed by reducing the flow path resistance of the inflow path from the liquid chamber to the inflow path resistance change unit while the volume of the liquid chamber is reduced by the volume change unit. A process of reducing the pressure of the liquid chamber by promoting the escape of pressure into the inflow passage; the elapsed time is reduced in the volume of the liquid chamber in the volume changing unit in the pressurizing process After that, the decompression process It may be the time until the inflow channel resistance changing unit starts the operation for reducing the flow resistance of the inflow channel Te.
According to the liquid discharge apparatus of this aspect, the pressure is suppressed from being transmitted to the inflow path in the pressurizing process by the operation of increasing the flow path resistance of the inflow path by the inflow path resistance changing unit. Therefore, the pressure generated by the volume changing unit in the pressurizing process can be efficiently transmitted to the nozzle. Further, in the decompression process, the negative pressure for promoting the separation of the liquid droplets can be easily generated in the liquid chamber by the operation in which the inflow path resistance changing unit reduces the flow path resistance of the inflow path. Further, by controlling the drive timings of the volume changing unit and the inflow path resistance changing unit, the liquid discharge amount can be easily controlled with high accuracy.

[3] In the liquid ejection device according to the above aspect, the pressure transmission adjusting unit adjusts the transmission of pressure from the liquid chamber to the inflow path by changing the flow path resistance of the inflow path. And the pressurizing process is performed in a state in which the flow path resistance of the inflow path is increased by the inflow path resistance changing unit and the transmission of pressure from the liquid chamber to the inflow path is suppressed. The pressure reducing process reduces the pressure of the liquid chamber by increasing the volume of the liquid chamber in the volume changing unit while the pressure of the liquid chamber is higher than the pressure before the pressurizing process. In the pressurization process, the elapsed time causes the volume changing unit to reduce the volume of the liquid chamber, and then causes the volume changing unit to start increasing the volume of the liquid chamber in the decompression process. Time between Good.
According to the liquid ejection device of this aspect, the pressure flow is suppressed from being transmitted to the inflow path in the pressurizing process by the operation in which the inflow path resistance changing unit increases the flow path resistance of the inflow path. Therefore, the pressure generated by the volume changing unit in the pressurizing process can be efficiently transmitted to the nozzle. In addition, the negative pressure generated by the volume changing unit in the decompression process can be efficiently transmitted to the nozzle, and the separation of the droplets can be promoted. In addition, by controlling the timing at which the volume of the liquid chamber is changed by the volume changing unit, the liquid discharge amount can be easily controlled with high accuracy.

[4] In the liquid ejection device of the above aspect, the flow path further includes an outflow path for discharging the liquid in the liquid chamber; and the pressure transmission adjustment unit is configured to supply the liquid from the liquid chamber to the outflow path. An inflow amount changing unit that adjusts the pressure transfer from the liquid chamber to the outflow passage by changing the inflow amount of the liquid; and the pressurizing process is performed by the inflow amount changing portion by the liquid flowing into the outflow passage. The inflow amount of the liquid chamber is reduced, and the pressure transmission from the liquid chamber to the outflow passage is suppressed. The decompression process is performed while the volume of the liquid chamber is reduced by the volume changing unit. In addition, the inflow amount changing unit is a process of reducing the pressure of the liquid chamber by increasing the inflow amount of the liquid into the outflow path; the elapsed time is the volume change in the pressurizing process Reduced the volume of the liquid chamber May be the time between the to said inflow amount changing unit in a vacuum processing starts to operate to increase the inflow of the liquid into the outlet channel.
According to the liquid discharge apparatus of this aspect, by having the outflow path, it is possible to suppress the liquid from staying in the liquid chamber, and it is possible to suppress the liquid discharge failure due to the liquid retention. Further, the bubbles in the liquid chamber can be discharged together with the liquid from the outflow path, and the occurrence of defective liquid discharge due to the bubbles in the liquid chamber can be suppressed. According to the liquid ejection apparatus of this aspect, in the pressurization process, the outflow of the liquid to the outflow path is suppressed by the inflow amount changing unit, and the pressure of the liquid chamber is suppressed from being transmitted to the outflow path. Therefore, the pressure generated by the volume changing unit in the pressurizing process can be efficiently transmitted to the nozzle. Further, in the decompression process, the inflow amount changing unit can easily generate a negative pressure in the liquid chamber for promoting the separation of the liquid droplets by increasing the amount of the liquid flowing out to the outflow path. In addition, by controlling the drive timings of the volume changing unit and the inflow rate changing unit, the liquid discharge amount can be easily controlled with high accuracy.

[5] In the liquid ejection device according to the above aspect, the flow resistance between the inflow path and the nozzle is R, the inertance between the inflow path and the nozzle is M, and the inflow path to the nozzle The relationship of √ (M / C) <R / 2 may be satisfied, where C is the compliance between the two.
According to the liquid ejection device of this aspect, the liquid in the liquid chamber is vibrated due to the pressure change in the liquid pressure process and the pressure reduction process, and the ejection of the liquid from the nozzle is inhibited.

[6] Another embodiment of the present invention is provided as a method for controlling a liquid ejection apparatus. This control method increases the pressure of the liquid chamber and communicates with the liquid chamber in a state where transmission of pressure to the liquid flow path connected to the liquid chamber containing the liquid is suppressed. A pressurizing step for starting the outflow of the liquid from the nozzle being disposed; and after the start of the outflow of the liquid from the nozzle by the pressurizing step, the liquid is flowing out from the nozzle in advance. A depressurization step of reducing the pressure of the liquid chamber when the elapsed time has elapsed and separating and flying droplets from the liquid of the nozzle; and before the depressurization step, the elapsed time, A discharge amount control step that is determined according to a target discharge amount of the liquid.
According to the control method of this aspect, in the pressurization step, the pressure change for starting the outflow of the liquid from the nozzle can be efficiently transmitted to the nozzle. In addition, the pressure change generated by the decompression step can efficiently separate the liquid and droplets of the nozzle, and the occurrence of defective liquid discharge is suppressed. Furthermore, by adjusting the elapsed time after execution of the pressurization step, the liquid discharge amount can be easily controlled with high accuracy.

  A plurality of constituent elements of each aspect of the present invention described above are not indispensable, and some or all of the effects described in the present specification are to be solved to solve part or all of the above-described problems. In order to achieve the above, it is possible to appropriately change, delete, replace with a new other component, and partially delete the limited contents of some of the plurality of components. In order to solve part or all of the above-described problems or to achieve part or all of the effects described in this specification, technical features included in one embodiment of the present invention described above. A part or all of the technical features included in the other aspects of the present invention described above may be combined to form an independent form of the present invention.

  The present invention can also be realized in various forms other than the liquid ejection apparatus and its control method. For example, a liquid ejection system, a liquid ejection system control method, a liquid ejection method in a liquid ejection apparatus or a liquid ejection system, a computer program for realizing those methods, a non-temporary recording medium on which the computer program is recorded, etc. Can be realized.

1 is a schematic block diagram illustrating a configuration of a liquid ejection device according to a first embodiment. FIG. 3 is a schematic cross-sectional view showing an internal configuration of a head unit in the first embodiment. The flowchart which shows the control process of the control part in the discharge process of 1st Embodiment. Explanatory drawing which shows an example of the timing chart of the discharge process in 1st Embodiment. FIG. 6 is a first schematic diagram illustrating the operation of the head unit in the ejection processing of the first embodiment. FIG. 6 is a second schematic diagram illustrating the operation of the head unit in the ejection processing of the first embodiment. FIG. 9 is a third schematic diagram illustrating the operation of the head unit in the ejection processing of the first embodiment. Explanatory drawing which shows the time change of the pressure in a liquid chamber during execution of discharge processing. Explanatory drawing which shows an example of the map used in the discharge amount control process of 1st Embodiment. Schematic which shows the equivalent circuit of the head part of 2nd Embodiment. Explanatory drawing which shows an example of the timing chart of the discharge process in 3rd Embodiment. FIG. 10 is a first schematic diagram illustrating an operation of a head unit in a discharge process according to a third embodiment. FIG. 10 is a second schematic diagram illustrating the operation of the head unit in the ejection processing of the third embodiment. FIG. 10 is a schematic block diagram illustrating a configuration of a liquid ejection device in a fourth embodiment. FIG. 10 is a schematic cross-sectional view showing an internal configuration of a head unit in a fourth embodiment. Explanatory drawing which shows an example of the timing chart of the discharge process in 4th Embodiment. FIG. 10 is a first schematic diagram illustrating an operation of a head unit in a discharge process according to a fourth embodiment. FIG. 10 is a second schematic diagram showing the operation of the head unit in the ejection processing of the fourth embodiment. FIG. 10 is a third schematic diagram illustrating the operation of the head unit in the ejection processing of the fourth embodiment.

A. First embodiment:
FIG. 1 is a schematic block diagram illustrating the overall configuration of a liquid ejection apparatus 100A according to the first embodiment. The liquid ejection apparatus 100A according to the first embodiment includes a tank 10, a pressure adjustment unit 15, a supply path 16, a head unit 20A, and a control unit 25.

  The tank 10 contains a liquid. The liquid is, for example, ink having a predetermined viscosity. The liquid in the tank 10 is supplied to the head unit 20A through the supply path 16 connected to the head unit 20A.

  The pressure adjusting unit 15 is provided in the supply path 16 and adjusts the pressure of the liquid supplied to the head unit 20 </ b> A through the supply path 16 to a predetermined pressure. The pressure adjustment unit 15 includes a pump that sucks liquid from the tank 10 and a valve that opens and closes so that the pressure on the head unit 20A side becomes a predetermined pressure (not shown). The head unit 20 </ b> A discharges the liquid supplied from the supply path 16. The operation of the head unit 20A is controlled by the control unit 25. The configuration of the head unit 20A will be described later.

  The control unit 25 is configured as a computer having a CPU and a memory, and the CPU reads out and executes control programs and instructions stored in the memory, thereby executing various functions for controlling the liquid ejection apparatus 100A. Realize. The control program may be recorded on various tangible recording media that are not temporary. The control unit 25 may be configured by a circuit. The control unit 25 executes an ejection process for causing the head unit 20A to eject a liquid. The discharge process will be described later.

  FIG. 2 is a schematic cross-sectional view showing the internal configuration of the head portion 20A. FIG. 2 schematically shows the configuration of the head portion 20 </ b> A on a cut surface passing through the central axis (not shown) of the nozzle 31 and the inflow path 40. The head unit 20 </ b> A includes a liquid chamber 30, a nozzle 31, and an inflow path 40.

  The liquid chamber 30 is provided in the metal casing 21 of the head portion 20A. The liquid chamber 30 is configured as a room surrounded by the inner wall surface 30w and has a space for storing the liquid LQ. The nozzle 31 discharges the liquid LQ in the liquid chamber 30 as droplets DR to the outside of the head unit 20A. The nozzle 31 is formed as a through hole that penetrates the casing 21 of the head portion 20A. The nozzle 31 communicates with the liquid chamber 30 through a communication port 33 that opens on the bottom wall surface that is one of the inner wall surfaces 30 w of the liquid chamber 30. In the first embodiment, the nozzle 31 opens along the direction of gravity. The head unit 20A may include two or more nozzles 31 and two liquid chambers 30.

  The inflow path 40 is a flow path for the liquid LQ connected to the liquid chamber 30. It is provided in the housing 21 of the head portion 20A. The inflow path 40 communicates with the liquid chamber 30 through an inlet 41 that is open in the liquid chamber 30. The inflow path 40 is connected to the supply path 16 (FIG. 1), and supplies the liquid LQ supplied from the supply path 16 to the liquid chamber 30.

  The head unit 20 </ b> A further includes a volume changing unit 35 and an inflow path resistance changing unit 50. The volume changing unit 35 discharges the droplet DR from the nozzle 31 by changing the volume of the liquid chamber 30 under the control of the control unit 25 (FIG. 1). The volume changing unit 35 is accommodated in the first drive chamber 36. The first drive chamber 36 is a room provided above the liquid chamber 30 in the housing 21 of the head portion 20A. The liquid chamber 30 and the first drive chamber 36 are airtightly separated from each other by a diaphragm 37.

  The diaphragm 37 forms an upper wall surface that is one of the inner wall surfaces 30 w of the liquid chamber 30. In the first embodiment, the diaphragm 37 is formed of a metal thin film member. The diaphragm 37 may be configured by another flexible deformable thin film member such as elastic rubber.

  The volume changing unit 35 is connected to the upper surface of the diaphragm 37 and applies an external force to the diaphragm 37 to bend and deform it. In the first embodiment, the volume changing unit 35 is configured by a piezo element, and flexes and deforms the diaphragm 37 vertically by expanding and contracting in the vertical direction. As described above, the diaphragm 37 constitutes a part of the inner wall surface 30 w of the liquid chamber 30. When the diaphragm 37 is bent and deformed, the volume of the liquid chamber 30 changes. The volume changing unit 35 changes the volume of the liquid chamber 30 and changes the pressure in the liquid chamber 30 by displacing the diaphragm 37 in the vertical direction.

  FIG. 2 illustrates a flat state in which the diaphragm 37 is not bent and deformed. Hereinafter, the length in the expansion / contraction direction of the volume changing unit 35 at this time is also referred to as “reference length” of the volume changing unit 35, and the volume of the liquid chamber 30 is also referred to as “reference volume”. When the volume changing unit 35 extends from the reference length, the volume of the liquid chamber 30 decreases from the reference volume. On the other hand, when the volume changing unit 35 contracts from the reference length, the volume of the liquid chamber 30 increases from the reference volume.

  The inflow path resistance changing unit 50 is provided in the inflow path 40. The inflow path resistance changing unit 50 changes the volume of the inflow path 40 and changes the flow path resistance of the inflow path 40 under the control of the control unit 25 (FIG. 1). The flow of the liquid LQ between the liquid chamber 30 and the inflow path 40 is controlled. As will be described later, the inflow path resistance changing unit 50 controls the inflow of the liquid LQ from the liquid chamber 30 to the inflow path 40 and adjusts the transmission of pressure from the liquid chamber 30 to the inflow path 40. Function as.

  The inflow path resistance changing unit 50 includes a drive unit 51 and a valve body 52. The drive unit 51 is accommodated in the second drive chamber 53. The second drive chamber 53 is a room provided in the housing 21 of the head unit 20A. In the first embodiment, the second drive chamber 53 is provided above the inflow path 40. The second drive chamber 53 is provided above the liquid chamber 30 and adjacent to the first drive chamber 36 in the horizontal direction. The inflow path 40 and the second drive chamber 53 communicate with each other through a through hole 54 that extends linearly.

  The valve body 52 is a metal columnar member. The valve body 52 is disposed across the inflow path 40 and the second drive chamber 53 through the through hole 54 described above. Hereinafter, the end portion 56 on the inflow path 40 side of the valve body 52 is referred to as a “front end portion 56”, and the end portion 56 on the second drive chamber 53 side is referred to as a “rear end portion 57”. In the first embodiment, the valve body 52 is disposed such that the front end portion 56 is set downward and the rear end portion 57 is set upward, and the longitudinal direction thereof is along the gravity direction. In 1st Embodiment, the front-end | tip part 56 of the valve body 52 is comprised as a hemispherical convex part. Note that the surface of the valve body 52 disposed in the inflow path 40 can be interpreted as constituting a part of the inner wall surface of the inflow path 40.

  The drive unit 51 is connected to the rear end portion 57 of the valve body 52 and applies an external force to the valve body 52 to displace the valve body 52 along its longitudinal direction. In the first embodiment, the drive unit 51 is configured by a piezo element, and moves the valve body 52 up and down in the second drive chamber 53 by vertically expanding and contracting. A seal member that seals the second drive chamber 53 in airtight contact with the side surface of the valve body 52 is disposed in the through hole 54 (not shown). The valve body 52 performs a piston motion while rubbing the inner peripheral surface of the seal portion.

  FIG. 2 illustrates a state in which the drive unit 51 is contracted and the length of the valve body 52 protruding into the inflow path 40 is the shortest. When the drive unit 51 extends from this state, the valve body 52 moves downward, the length of the valve body 52 protruding into the inflow path 40 increases, the volume of the inflow path 40 is reduced, and the inflow path 40 is reduced. The channel resistance increases. Conversely, when the drive unit 51 contracts, the volume of the inflow path 40 increases and the flow path resistance of the inflow path 40 is reduced.

  In the first embodiment, the inflow passage 40 has a valve seat portion 43. The valve seat portion 43 is provided at a position facing the distal end portion 56 of the valve body 52. The valve seat portion 43 is configured as a tapered portion whose diameter gradually decreases in the moving direction when the valve body 52 moves toward the inflow path 40. When the valve body 52 protrudes most into the inflow passage 40, the tip 56 contacts the inner wall surface of the valve seat portion 43 to close the inflow passage 40. In the state where the inflow path 40 is closed, the flow of the liquid LQ in the inflow path 40 may not be completely blocked. Thus, in 1st Embodiment, the inflow path resistance change part 50 moves the valve body 52 in the direction where the flow path resistance of the inflow path 40 increases, and closes the inflow path 40. FIG. Further, the valve body 52 is moved in a direction in which the flow path resistance of the inflow path 40 is reduced, and the inflow path 40 is opened.

  In addition to FIG. 2, the discharge process performed by the control unit 25 in the liquid discharge apparatus 100A will be described with reference to FIGS. 3, 4, and 5A to 5C. FIG. 3 is a flowchart showing a control process of the control unit 25 in the discharge process of the first embodiment. FIG. 4 is an explanatory diagram illustrating an example of a timing chart representing operations of the volume changing unit 35 and the inflow path resistance changing unit 50 in the discharge process of the first embodiment. In FIG. 4, the change in the volume of the liquid chamber 30 by the volume changing unit 35 is shown in the lower part of the drawing, and the displacement of the valve body 52 by the inflow path resistance changing unit 50 is shown in the upper drawing. 5A to 5C are schematic diagrams schematically showing the operation of the head unit 20A in the ejection processing of the first embodiment.

  The control unit 25 sets the head unit 20A to the initial state shown in FIG. 2 before starting the execution of the ejection process. In this initial state, the control unit 25 sets the volume of the liquid chamber 30 to the reference volume described above, and causes the inflow channel 40 to be opened by the inflow channel resistance changing unit 50. Further, the control unit 25 adjusts the pressure of the liquid chamber 30 to a predetermined reference pressure equal to or lower than the meniscus pressure resistance of the nozzle 31 by the pressure adjusting unit 15 (FIG. 1).

  Step 1 (FIG. 3) is a discharge amount control step of executing a discharge amount control process for determining an elapsed time ΔT, which will be described later, according to a target discharge amount that is a target value of the amount of liquid LQ discharged from the nozzle 31. is there. The elapsed time ΔT and the discharge amount control process will be described after describing the pressurizing process in step 2 and the depressurizing process in step 3.

Step 2 (FIG. 3) starts the outflow of the liquid LQ from the nozzle 31 by increasing the pressure of the liquid chamber 30 in a state where the transmission of the pressure to the inflow path 40 which is the flow path of the liquid LQ is suppressed. This is a pressurizing step. In step 2, the control unit 25 executes the following pressurizing process. In the pressurization process, the control unit 25 first increases the flow path resistance of the inflow path 40 to the inflow path resistance changing unit 50 so that the transmission of pressure from the liquid chamber 30 to the inflow path 40 is suppressed. To do. At time t ₀ , the control unit 25 extends the drive unit 51 of the inflow path resistance changing unit 50, displaces the valve body 52 downward by ΔL, and closes the inflow path 40 (FIGS. 4 and 5A).

In the pressurization process, the control unit 25 further decreases the volume of the liquid chamber 30 by the volume changing unit 35 and increases the pressure of the liquid chamber 30. At time t ₁ , the control unit 25 causes the volume changing unit 35 to instantaneously reduce the volume of the liquid chamber 30 from the reference volume by ΔV that is a predetermined decrease (FIG. 4). As a result, the pressure in the liquid chamber 30 increases, and the outflow of the liquid LQ from the nozzle 31 is started (FIG. 5B).

  In the pressurization process, as described above, since the transmission of pressure from the liquid chamber 30 to the inflow path 40 is suppressed, the pressure generated by the operation of the volume changing unit 35 is directed toward the inflow path 40. Escape is suppressed. Therefore, it is suppressed that the driving force that causes the liquid LQ to flow out from the nozzle 31 is reduced, and the efficiency of the liquid LQ from the nozzle 31 is increased.

  In step 3 (FIG. 3), after the liquid LQ starts flowing out of the nozzle 31 by the pressurizing step, the pressure in the liquid chamber 30 is reduced while the liquid LQ flows out of the nozzle 31, This is a decompression step in which the droplets DR are separated from the liquid LQ of the nozzle 31 and fly. In step 3, the control unit 25 performs the following decompression process.

  In the depressurization process, while the liquid LQ flows out from the nozzle 31, when an elapse time ΔT to be described later elapses, the inflow path resistance changing unit 50, which is a pressure transmission adjusting unit, is driven to drive the liquid chamber 30. Reduce pressure. “While the liquid LQ is flowing out from the nozzle 31” means that the state in which the liquid LQ hangs down from the nozzle 31 is continued. This period is a period in which the state in which the volume of the liquid chamber 30 is reduced from the reference volume by the volume changing unit 35 is maintained, and the pressure of the liquid chamber 30 remains higher than before the pressurization process is performed. It is a period.

Control unit 25, at time t ₂ during that period, the driving portion 51 of the inlet channel resistance changing unit 50 is contracted, the valve body 52 is displaced upward by [Delta] L, it opens the inlet channel 40 (FIG. 4 , FIG. 5C). Thereby, the volume of the inflow path 40 increases, and the flow path resistance of the inflow path 40 is reduced. For this reason, the escape of pressure from the liquid chamber 30 to the inflow path 40 is promoted, the pressure of the liquid chamber 30 is reduced, and a negative pressure is generated that pulls the liquid LQ of the nozzle 31 back toward the liquid chamber 30. By this negative pressure, separation of the droplet DR from the liquid LQ of the nozzle 31 is promoted, and the droplet DR starts to fly.

The discharge amount control process in step 1 (FIG. 3) will be described. The discharge amount control process is a process for determining the elapsed time ΔT according to the target discharge amount. The elapsed time ΔT is the time for determining the start timing of the decompression process, and is the time between the execution of the pressurization process and the start of the decompression process. In the first embodiment, the elapsed time ΔT is determined by reducing the flow path resistance of the inflow path 40 by the inflow path resistance changing unit 50 after the volume changing unit 35 reduces the volume of the liquid chamber 30 in the pressurizing process. This is the time until the operation to start (time t _{1 to} t _{2 in} FIG. 4).

Please refer to FIG. FIG. 6 shows a graph showing the change over time of the pressure in the liquid chamber 30 during the execution of the discharge process. In FIG. 6, time t ₁ is the time immediately after the execution of the pressurizing process. Graphs Ga, Gb, and Gc respectively show time changes in pressure when the time at which the decompression process is started is delayed in order of t _2a , t _2b , and t _2c . Graphs Ga, Gb, and Gc in FIG. 6 respectively show pressure changes in the liquid chamber 30 when the elapsed time ΔT is set to ΔTa, ΔTb, ΔTc (ΔTa <ΔTb <ΔTc) and gradually longer.

As the graphs Ga, Gb, and Gc in FIG. 6 indicate, the longer the elapsed time ΔT, the more linear the pressure in the liquid chamber 30 at the times t _2a , t _2b , and t _2c when the decompression process is started. It is gradually decreasing. This is presumed to be because the outflow amount of the liquid LQ from the nozzle 31 increases linearly as the elapsed time ΔT increases. That is, the longer the elapsed time ΔT, the larger the amount of liquid LQ ejected in the ejection process, and the larger the size of the droplet DR. In the discharge amount control process, the control unit 25 determines the elapsed time ΔT according to the target discharge amount by using the correlation between the elapsed time ΔT and the outflow amount of the liquid LQ from the nozzle 31.

  FIG. 7 is an explanatory diagram illustrating an example of a map MP used by the control unit 25 to determine the elapsed time ΔT. The map MP has a relationship in which the elapsed time ΔT increases linearly as the target discharge amount Tv increases. The map MP is stored in advance in a storage unit (not shown) of the liquid ejection apparatus 100A. In the discharge amount control process of step 1, the control unit 25 refers to the map MP and acquires the elapsed time ΔT with respect to the target discharge amount Tv. After executing the pressurization process in step 2, the control unit 25 waits for the elapsed time ΔT determined in the discharge amount control process to start executing the decompression process in step 3. Thereby, in the liquid ejection apparatus 100A, the droplet DR having a size corresponding to the target ejection amount Tv is ejected.

  In the liquid ejection apparatus 100A, the control unit 25 uses a table or a function expression prepared in advance indicating the correspondence between the target ejection amount Tv and the elapsed time ΔT instead of the map MP, for the target ejection amount Tv. The elapsed time ΔT may be determined. Or the control part 25 is good also as what obtains the output of the elapsed time (DELTA) T with respect to the target discharge amount Tv using the circuit showing such a functional equation.

  As described above, according to the liquid ejection device 100A of the first embodiment, in the pressurization process, the pressure transmission from the liquid chamber 30 to the inflow path 40 is suppressed. The nozzle 31 can be efficiently transmitted. Further, in the decompression process, a negative pressure that promotes the separation of the droplets DR can be easily generated in the liquid chamber 30 by the operation in which the inflow path resistance changing unit 50 reduces the flow path resistance of the inflow path 40. . According to the liquid ejection device 100A of the first embodiment, by adjusting the elapsed time ΔT that determines the operation timing of the inflow path resistance changing unit 50, the ejection amount of the liquid LQ can be easily performed with high accuracy. In the liquid ejection device 100A of the first embodiment, the pressure reducing process is executed by the inflow path resistance changing unit 50 different from the volume changing unit 35 that executes the pressurizing process. Therefore, even if the elapsed time ΔT is shorter than the natural period of the volume changing unit 35, the decompression process can be started at an appropriate timing determined by the elapsed time ΔT. That is, the start timing of the decompression process is suppressed from being affected by the operation performance of the volume changing unit 35, and the droplet DR can be separated at a more suitable timing, and the droplet DR is discharged from the nozzle 31. Controllability is improved. In addition, since the timing at which the droplet DR is separated from the liquid LQ of the nozzle 31 can be controlled with higher accuracy, it is possible to suppress the droplet DR from being unnecessarily pulled, and generation of unnecessary mist or droplet DR. The deformation of the shape is suppressed. Therefore, deterioration of the flight state and landing state of the droplet DR is suppressed, and the reliability of ejection of the droplet DR by the head unit 20A is enhanced. In addition, according to the liquid ejection device 100A of the first embodiment and the control method for executing the ejection processing, various functions and effects described in the first embodiment can be achieved.

B. Second embodiment:
FIG. 8 is a schematic diagram illustrating an equivalent circuit of the head unit 20B included in the liquid ejection apparatus 100B of the second embodiment. The configuration of the liquid ejection apparatus 100B of the second embodiment is the same as that of the liquid ejection apparatus 100A of the first embodiment, except that the head section 20B of the second embodiment is provided instead of the head section 20A of the first embodiment. The configuration is almost the same. The configuration of the head portion 20B of the second embodiment is substantially the same as the head portion 20A of the first embodiment, except that the configuration described below is designed to be satisfied. The liquid ejection device 100B of the second embodiment performs the same ejection process as described in the first embodiment.

  The flow path resistance R, inertance M, and compliance C between the inflow path 40 and the nozzle 31 of the head portion 20B are obtained as in the following formulas (1) to (3). The flow path resistance Rp and the inertance Mp of the inflow path 40 are values when the inflow path 40 is closed by the inflow path resistance changing unit 50.

R = Rp · Rn / (Rp + Rn) (1)
M = Mp · Mn / (Mp + Mn) (2)
C = Cn + Cr (3)
Rp: Flow path resistance of the inflow path 40, Rn: Flow path resistance of the nozzle 31 Mp: Inertance of the inflow path 40, Mn: Inertance of the nozzle 31 Cn: Compliance of the nozzle 31, Cr: Compliance of the liquid chamber 30

  R, M, and C have a correlation with the viscosity η, density ρ, and compressibility κ of the liquid LQ as shown in the following formulas (4) to (6).

R∝η (4)
M = ρ · (L / S) (5)
C∝ (V ・ κ) (6)
L: Channel length, S: Channel cross-sectional area, V: Volume

At this time, the relationship of the following inequality (7) is satisfied in the head portion 20B.
√ (M / C) <R / 2 (7)

  Thus, even when the pressure wave pulse P is applied to the liquid LQ in the liquid chamber 30 from the volume changing unit 35 in the pressurizing process, the liquid LQ in the liquid chamber 30 is suppressed from vibrating, and the liquid LQ Occurrence of ejection failure is suppressed. In addition, according to the liquid ejection apparatus 100B of the second embodiment and the control method for executing the ejection process, various functions and effects similar to those described in the first embodiment can be achieved.

C. Third embodiment:
With reference to FIG. 9, FIG. 10A, and FIG. 10B, the discharge process which the control part 25 performs in the liquid discharge apparatus 100C of 3rd Embodiment is demonstrated. FIG. 9 is an explanatory diagram illustrating an example of a timing chart representing operations of the volume changing unit 35 and the inflow path resistance changing unit 50 in the discharge process of the third embodiment. In FIG. 9, the change in the volume of the liquid chamber 30 by the volume changing unit 35 is shown in the lower part of the drawing, and the displacement of the valve body 52 by the inflow path resistance changing unit 50 is shown in the upper drawing. 10A and 10B are schematic views schematically showing the operation of the head unit 20C of the third embodiment in the ejection processing of the third embodiment.

  The configuration of the liquid ejection apparatus 100C of the third embodiment is substantially the same as the configuration of the liquid ejection apparatus 100A of the first embodiment (FIG. 1). The configuration of the head unit 20C of the third embodiment is substantially the same as the configuration of the head unit 20A of the first embodiment (FIG. 2). The flow of the control process of the control unit 25 in the discharge process of the third embodiment is substantially the same as the flow of the control process described in the first embodiment (FIG. 3). The discharge process of the third embodiment is the same as that of the first embodiment except that in the decompression process, a negative pressure for separating the droplet DR is generated in the liquid chamber 30 by the operation of the volume changing unit 35. It is almost the same as the discharge process.

  In step 1, the control unit 25 performs a discharge amount control process. In the discharge amount control process, the control unit 25 uses the map MP (FIG. 7) similar to that described in the first embodiment to determine the elapsed time ΔT corresponding to the target discharge amount Tv in advance before the decompression process. decide. In the third embodiment, the elapsed time ΔT is the time until the volume changing unit 35 starts to increase the volume of the liquid chamber 30 in the decompression process after the volume changing unit 35 reduces the volume of the liquid chamber 30 in the pressurizing process. Is the time between.

In step 2, the control unit 25 executes a pressurizing process. In the pressurizing process, the control unit 25 increases the flow resistance of the inflow path 40 to the inflow path resistance changing unit 50 functioning as a pressure transmission adjustment unit, as described in the first embodiment, A state is established in which the transmission of pressure from the chamber 30 to the inflow passage 40 is suppressed (time t _{0 in} FIG. 9). Then, the volume changing unit 35 reduces the volume of the liquid chamber 30 from the reference volume and increases the pressure of the liquid chamber 30 (time t ₁ in FIG. 9, FIG. 10A).

In step 3, the control unit 25 performs a decompression process. When the elapsed time ΔT has elapsed after the execution of the pressurizing process, the control unit 25 starts executing the decompression process (time t _{2 in} FIG. 9). In the depressurization process, the control unit 25 causes the volume changing unit 35 to increase the volume of the liquid chamber 30 to the reference volume while the pressure in the liquid chamber 30 is higher than the pressure before the pressurization process is performed. Is reduced (FIG. 10B). As a result, a negative pressure is generated in the liquid chamber 30 so as to draw the liquid LQ of the nozzle 31 back toward the liquid chamber 30, and the droplet DR can be separated from the liquid LQ of the nozzle 31.

  As described above, according to the liquid ejection device 100C of the third embodiment, since the inflow path resistance changing unit 50 increases the flow path resistance of the inflow path 40, the negative volume generated by the volume changing unit 35 in the decompression process. The pressure can be efficiently transmitted to the nozzle 31. Therefore, separation of the droplet DR from the liquid LQ of the nozzle 31 can be promoted in the ejection process. Further, by controlling the timing of reducing the volume of the liquid chamber 30 by the volume changing unit 35 after the pressurizing process, the discharge amount of the liquid LQ can be easily controlled with high accuracy. In addition, according to the liquid ejection apparatus 100C of the third embodiment and the control method for executing the ejection process, various functions and effects similar to those described in the first embodiment can be obtained.

D. Fourth embodiment:
FIG. 11 is a schematic block diagram illustrating an overall configuration of a liquid ejection apparatus 100D according to the fourth embodiment. The liquid ejection device 100D of the fourth embodiment has substantially the same configuration as the liquid ejection device 100A (FIG. 1) of the first embodiment except for the points described below. The liquid ejection apparatus 100D includes a pressurizing pump 60 instead of the pressure adjusting unit 15, and includes the head unit 20D of the fourth embodiment instead of the head unit 20A of the first embodiment. In addition, a discharge path 61, a liquid storage unit 63, a negative pressure generation source 64, and a circulation path 65 are added to the liquid ejection device 100D.

  The pressurizing pump 60 supplies the liquid in the tank 10 to the head unit 20 </ b> D through the supply path 16. The configuration of the head unit 20D will be described later. The discharge path 61 connects the head unit 20 </ b> D and the liquid storage unit 63. The liquid that has not been ejected by the head part 20 </ b> D is discharged to the liquid storage part 63 through the discharge path 61. A negative pressure generation source 64 is connected to the liquid storage unit 63. The negative pressure generation source 64 draws liquid from the head part 20 </ b> D through the discharge path 61 by setting the inside of the liquid storage part 63 to a negative pressure. The negative pressure generation source 64 is constituted by various pumps.

  In the liquid ejection device 100D, the pressurizing pump 60 and the negative pressure generation source 64 function as a liquid supply unit that generates a differential pressure in the supply path 16 and the discharge path 61 and supplies the liquid to the head unit 20D. Note that either the pressurizing pump 60 or the negative pressure generating source 64 may be omitted, and the liquid supply unit may be configured by either the pressurizing pump 60 or the negative pressure generating source 64 alone.

  The circulation path 65 is a flow path for circulating the liquid flowing out from the outflow path 70 of the head part 20D to the liquid chamber 30 of the head part 20D. The circulation path 65 connects the liquid storage unit 63 and the tank 10. The liquid discharged from the outflow path 70 of the head section 20D and stored in the liquid storage section 63 through the discharge path 61 is returned to the tank 10 through the circulation path 65, and again, the liquid chamber 30 of the head section 20D by the pressurizing pump 60. To be supplied. The outflow passage 70 and the liquid chamber 30 of the head portion 20D are shown in FIG. The circulation path 65 may be provided with a pump for sucking liquid from the liquid reservoir 63.

  In the liquid ejecting apparatus 100D, by providing the circulation path 65, the liquid LQ that has flowed out of the head portion 20D can be reused. Therefore, wasteful consumption of the liquid LQ can be suppressed, and the utilization efficiency of the liquid LQ is enhanced. The liquid storage unit 63 and the tank 10 may be provided with an adjustment unit that adjusts various states such as the concentration, viscosity, and temperature of the liquid LQ to be reused. Further, the discharge path 61 and the circulation path 65 may be provided with a filter unit for removing bubbles and foreign matters contained in the liquid LQ.

  FIG. 12 is a schematic cross-sectional view showing the internal configuration of the head unit 20D of the fourth embodiment. FIG. 12 schematically illustrates the configuration of the head portion 20 </ b> D on a cut surface passing through the central axis of the nozzle 31, the inflow path 40, and the outflow path 70. In FIG. 12, similarly to FIG. 2, the volume changing unit 35 is the reference length, the volume of the liquid chamber 30 is the reference volume, and the inflow path 40 is opened by the inflow path resistance changing unit 50. The state is illustrated.

  The configuration of the head unit 20D of the fourth embodiment is substantially the same as the configuration of the head unit 20A (FIG. 2) of the first embodiment, except that an outflow path 70 and an inflow amount changing unit 80 are added. It is. The head unit 20D may include two or more nozzles 31 and two liquid chambers 30.

  The outflow path 70 is one of the flow paths connected to the liquid chamber 30 and is provided in the housing 21. The outflow path 70 is connected to the discharge path 61. The outflow passage 70 causes the liquid LQ to flow out from the liquid chamber 30 through the outflow port 71 opened in the liquid chamber 30. In the fourth embodiment, the outflow channel 70 and the outflow port 71 are provided in a region opposite to the inflow channel 40 and the inflow port 41 with the volume changing unit 35 sandwiched in the horizontal direction in the head unit 20D.

  In the liquid ejection device 100D, the liquid LQ that has not been ejected is discharged from the head portion 20D through the outflow path 70. Thereby, in the liquid chamber 30, the flow of the liquid LQ from the inflow path 40 toward the outflow path 70 can be generated. Therefore, deterioration of the liquid LQ caused by the retention of the liquid LQ in the head portion 20D, such as deposition of sediment components in the liquid LQ in the head portion 20D and change in liquid concentration accompanying the evaporation of the liquid, is suppressed. Therefore, the occurrence of defective discharge of the droplet DR from the nozzle 31 due to the deterioration of the liquid LQ in the liquid chamber 30 is suppressed. Further, in the liquid ejection device 100D, bubbles generated by the outside air entering the liquid chamber 30 can be discharged from the outflow path 70 together with the liquid LQ. Therefore, the occurrence of defective discharge of the droplet DR from the nozzle 31 due to the bubbles in the liquid chamber 30 is suppressed.

  The inflow amount changing unit 80 is provided in the outflow passage 70. The inflow rate changing unit 80 changes the flow resistance of the outflow channel 70 by changing the volume of the outflow channel 70 under the control of the control unit 25 (FIG. 11), and flows into the outflow channel 70 from the liquid chamber 30. The inflow amount of the liquid LQ to be controlled is controlled. In the head part 20 </ b> D, the inflow amount changing unit 80 adjusts the inflow amount of the liquid LQ from the liquid chamber 30 to the outflow path 70, thereby adjusting the pressure transmitted from the liquid chamber 30 to the outflow path 70. In the fourth embodiment, in addition to the volume changing unit 35, the inflow amount changing unit 80 is included in the pressure transmission adjusting unit that adjusts the pressure transmitted from the liquid chamber 30 to the flow paths 40 and 70.

  The inflow amount changing unit 80 includes a drive unit 81 and a valve body 82. The drive unit 81 and the valve body 82 of the inflow amount changing unit 80 have the same configuration as the drive unit 51 and the valve body 82 of the inflow path resistance changing unit 50. The drive unit 81 of the inflow amount changing unit 80 is accommodated in the third drive chamber 83. The third drive chamber 83 is a room provided in the casing 21 of the head unit 20D. The third drive chamber 83 is provided above the outflow passage 70. The third drive chamber 83 and the outflow passage 70 are communicated with each other through a through hole 84 that extends linearly.

  The valve body 82 is disposed in the through hole 84 so that the distal end portion 86 is exposed to the outflow passage 70. In the through hole 84, a seal member is disposed (not shown) as in the case of the through hole 54 of the inflow path resistance changing unit 50. In addition, it can be interpreted that the surface of the valve body 82 arranged in the outflow passage 70 constitutes a part of the inner wall surface of the outflow passage 70.

  In the inflow amount changing unit 80, the drive unit 81 connected to the rear end portion 87 of the valve body 82 expands and contracts in the vertical direction, thereby causing the valve body 82 to perform a piston motion up and down. In the inflow amount changing unit 80, the extension of the drive unit 81 reduces the volume of the outflow path 70 and increases the flow path resistance of the outflow path 70. On the contrary, when the drive part 81 contracts, the volume of the outflow path 70 increases and the flow path resistance of the outflow path 70 is reduced.

  In the fourth embodiment, the outflow passage 70 has a valve seat portion 73 similar to the valve seat portion 43 of the inflow passage 40. The valve seat portion 73 is provided at a position facing the distal end portion 86 of the valve body 82 of the inflow amount changing portion 80. When the valve body 82 protrudes most into the outflow passage 70, the tip end portion 86 comes into contact with the inner wall surface of the valve seat portion 73 and closes the outflow passage 70. Thus, the inflow amount changing unit 80 moves the valve element 82 in the direction in which the flow path resistance of the outflow path 70 increases, and closes the outflow path 70. Further, the valve body 82 is moved in a direction in which the flow path resistance of the outflow path 70 is reduced, and the outflow path 70 is opened.

  In addition to FIG. 12, the discharge process performed by the control unit 25 in the liquid discharge apparatus 100D will be described with reference to FIGS. 13 and 14A to 14C. FIG. 13 is an explanatory diagram illustrating an example of a timing chart representing operations of the volume changing unit 35 and the inflow path resistance changing unit 50 in the discharge process of the fourth embodiment. In FIG. 13, the change in the volume of the liquid chamber 30 by the volume changing unit 35 is shown in the lower part of the drawing, the displacement of the valve body 52 by the inflow path resistance changing unit 50 is shown in the middle of the drawing, and the valve element by the inflow amount changing unit 80. The displacement of 82 is shown in the upper part of the drawing. 14A to 14C are schematic views schematically illustrating the operation of the head unit 20A in the ejection processing of the fourth embodiment.

  The flow of the control process of the control unit 25 in the discharge process of the fourth embodiment is substantially the same as the flow of the control process described in the first embodiment (FIG. 3). The discharge process of the fourth embodiment is the same as that of the first embodiment except that in the decompression process, a negative pressure for separating the droplets DR is generated in the liquid chamber 30 by the operation of the inflow amount changing unit 80. This is almost the same as the discharge process.

  The control unit 25 sets the head unit 20A to the initial state shown in FIG. 12 before starting the execution of the ejection process. In this initial state, the control unit 25 closes the outflow path 70 by the valve body 82 of the inflow amount changing unit 80. By closing the outflow path 70, the amount of the liquid LQ flowing into the outflow path 70 is reduced, and the pressure from the liquid chamber 30 to the outflow path 70 is suppressed from being released. Moreover, the control part 25 makes the volume of the liquid chamber 30 the reference | standard volume mentioned above, and makes the inflow path 40 open by the inflow path resistance change part 50. FIG. Then, the pressure adjusting unit 15 (FIG. 1) adjusts the pressure in the liquid chamber 30 to a predetermined reference pressure equal to or lower than the meniscus pressure resistance of the nozzle 31.

  In step 1, the control unit 25 performs a discharge amount control process. In the discharge amount control process, the control unit 25 uses the map MP (FIG. 7) similar to that described in the first embodiment to determine the elapsed time ΔT corresponding to the target discharge amount Tv in advance before the decompression process. decide. In the fourth embodiment, the elapsed time ΔT is obtained by reducing the volume of the liquid chamber 30 in the volume changing unit 35 in the pressurizing process, and then in the inflow amount changing unit 80 in the pressure reducing process. This is the time until the operation for increasing the inflow amount is started.

In step 2, the control unit 25 executes a pressurizing process. In the pressurizing process, the control unit 25 increases the flow resistance of the inflow path 40 to the inflow path resistance changing unit 50 functioning as a pressure transmission adjustment unit, as described in the first embodiment, The pressure is transferred from the chamber 30 to the inflow path 40 (time t ₀ in FIG. 13, FIG. 14A). Then, the volume changing unit 35 reduces the volume of the liquid chamber 30 from the reference volume and increases the pressure of the liquid chamber 30 (time t ₁ in FIG. 13, FIG. 14B).

In step 3, the control unit 25 performs a decompression process. When the elapsed time ΔT has elapsed after execution of the pressurizing process, the control unit 25 starts executing the decompression process (time t _{2 in} FIG. 13). While the liquid LQ is flowing out from the nozzle 31, the control unit 25 causes the inflow amount changing unit 80 to start an operation for increasing the inflow amount of the liquid LQ into the outflow path 70 (FIG. 14C). In the fourth embodiment, the control unit 25 contracts the driving unit 81 of the inflow amount changing unit 80, moves the valve body 82 upward, and opens the outflow channel 70, whereby the liquid LQ flows into the outflow channel 70. Increase the amount. Accordingly, the pressure in the liquid chamber 30 can be released to the outflow path 70, and the pressure in the liquid chamber 30 is reduced. Therefore, a negative pressure is generated in the liquid chamber 30 so as to draw the liquid LQ of the nozzle 31 back toward the liquid chamber 30, and the droplet DR can be separated from the liquid LQ of the nozzle 31.

  As described above, according to the liquid ejection device 100D of the fourth embodiment, in the decompression process, the inflow amount changing unit 80 increases the inflow amount of the liquid LQ into the outflow passage 70, thereby causing the droplets DR to be ejected from the nozzle 31. The negative pressure for separating from the liquid LQ can be easily generated. According to the liquid ejection device 100D of the fourth embodiment, the ejection amount of the liquid LQ can be easily performed with high accuracy by adjusting the elapsed time ΔT that determines the operation timing of the inflow amount changing unit 80 after the pressurizing process. it can. In the liquid ejection device 100D of the fourth embodiment, the pressure reduction process is executed by the inflow amount changing unit 80 different from the volume changing unit 35 that executes the pressurizing process. Therefore, the start timing of the decompression process is suppressed from being affected by the operation performance of the volume changing unit 35, and the droplet DR can be separated at a more suitable timing. In addition, according to the liquid ejection apparatus 100D of the fourth embodiment and the control method for executing the ejection process, various effects described in the first embodiment can be achieved.

E. Other embodiments:
The various configurations described in the above embodiments can be modified as follows, for example. Any of the other embodiments described below is positioned as an example of an embodiment for carrying out the invention, like the above-described embodiments.

E1. Other Embodiment 1:
In each of the above embodiments, the volume changing unit 35, the driving unit 51 of the inflow path resistance changing unit 50, and the driving unit 81 of the inflow amount changing unit 80 are configured by piezoelectric elements. On the other hand, the volume changing unit 35 and the driving units 51 and 81 may be configured by an actuator other than the piezoelectric element. The volume changing unit 35 and the driving units 51 and 81 may be configured by other actuators such as an air cylinder, a solenoid, and a magnetostrictive element, for example.

E2. Other embodiment 2:
In each of the embodiments described above, the volume changing unit 35 changes the volume of the liquid chamber 30 by bending and deforming the diaphragm 37 constituting a part of the inner wall surface 30 w of the liquid chamber 30. On the other hand, the volume changing unit 35 may change the volume of the liquid chamber 30 with another configuration. The volume changing unit 35 is configured to change the volume of the liquid chamber 30 by, for example, moving a valve body such as the valve body 52 of the inflow path resistance changing unit 50 toward the communication port 33 of the nozzle 31. There may be.

E3. Other embodiment 3:
In each of the above embodiments, the inflow path resistance changing unit 50 operates so as to open and close the inflow path 40. However, the inflow path resistance changing unit 50 does not have to make the inflow path 40 completely closed or open. The inflow path resistance changing unit 50 may change the flow path resistance of the inflow path 40 by an operation of changing the volume of the inflow path 40. In this case, the valve seat 43 of the inflow path 40 may be omitted. The same applies to the inflow amount changing portion 80 and the valve seat portion 73 of the outflow passage 70. In each of the above embodiments, the operation of changing the volume of the inflow channel 40 by the inflow channel resistance changing unit 50 can be interpreted as a configuration for changing the flow path cross-sectional area of the inflow channel 40. The same applies to the operation of changing the volume of the outflow passage 70 by the inflow amount changing unit 80.

E4. Other embodiment 4:
In each said embodiment, the inflow path resistance change part 50 displaces the valve body 52 by the drive part 51, changes the volume of the inflow path 40, and changes the flow path resistance of the inflow path 40. FIG. On the other hand, the inflow path resistance changing unit 50 may change the flow path resistance of the inflow path 40 by changing the volume of the inflow path 40 by a configuration other than the configuration in each of the above embodiments. For example, the inflow path resistance changing unit 50 may change the volume of the inflow path 40 by flexing and deforming a diaphragm that forms a part of the inner wall surface of the inflow path 40, like the volume changing unit 35. Further, the inflow path resistance changing unit 50 may be configured to change the flow path resistance of the inflow path 40 by changing the volume of the inflow path 40 by a shutter wall portion that moves across the inflow path 40. . In the inflow amount changing unit 80, the same configuration modification may be applied.

E5. Other embodiment 5:
The head unit 20C included in the liquid discharge device 100C of the third embodiment and the head unit 20D included in the liquid discharge device 100D of the fourth embodiment satisfy the relationship of the inequality (7) described in the second embodiment. It may be configured.

E6. Other embodiment 6:
In the liquid ejection device 100D of the fourth embodiment, the inflow amount changing unit 80 changes the inflow amount of the liquid LQ to the outflow passage 70 by causing the valve body 82 to perform a piston motion to change from the liquid chamber 30 to the outflow passage 70. The pressure transmission state is adjusted. On the other hand, the inflow amount changing unit 80 may change the inflow amount of the liquid LQ to the outflow passage 70 and adjust the pressure transmission state from the liquid chamber 30 to the outflow passage 70 by another configuration. Good. The inflow amount changing unit 80 may be configured by a pump that sucks the liquid LQ from the liquid chamber 30 to the outflow path 70. In the case of this configuration, the control unit 25 stops the driving of the pump when the pressurizing process is executed, and reduces the inflow amount of the liquid LQ into the outflow path 70, so that the outflow path 70 from the liquid chamber 30. The state where the transmission of pressure to is suppressed. In the depressurization process, when the elapsed time ΔT elapses, the pump is started to reduce the pressure in the liquid chamber 30. The inflow amount changing unit 80 may be the negative pressure generation source 64. The inflow amount changing unit 80 may be configured by a valve such as a negative pressure valve that adjusts the inflow amount of the liquid LQ into the outflow passage 70 by an opening / closing operation.

E7. Other embodiment 7:
In the first embodiment, the second embodiment, and the third embodiment, the outflow passage 70 and the inflow amount changing unit 80 described in the fourth embodiment may be provided in the head units 20A, 20B, and 20C. In this case, it is desirable that the control unit 25 drives the inflow amount changing unit 80 so that the transmission of pressure to the outflow passage 70 is suppressed when the pressurizing process or the depressurizing process is performed. .

E8. Other embodiment 8:
In the liquid ejection devices 100C and 100D of the third embodiment and the fourth embodiment, a configuration in which the circulation path 65 is omitted and the liquid LQ is not circulated may be applied. For example, a configuration in which the liquid LQ that has flowed out to the discharge path 61 is directly discharged to the outside may be applied.

E9. Other embodiment 9:
In the discharge process of each of the embodiments described above, the discharge amount control process is performed in step 1. In contrast, the discharge amount control process may be executed at the time of the discharge process, and may be executed at a timing other than during the execution of the discharge process. The control unit 25 may collectively determine the elapsed time ΔT used in each discharge process in advance according to the target discharge amount Tv before starting execution of a plurality of discharge processes. The discharge amount control process only needs to be performed at least before the decompression process is performed.

E10. Other embodiment 10:
In the decompression process of the first embodiment, the second embodiment, and the third embodiment, the control unit 25 drives the volume changing unit 35 together with the inflow path resistance changing unit 50 that is a pressure transmission adjusting unit, and the liquid chamber. The pressure of 30 may be reduced. In the decompression process of the fourth embodiment, the control unit 25 may drive the volume changing unit 35 together with the inflow amount changing unit 80 which is a pressure transmission adjusting unit to reduce the pressure in the liquid chamber 30. . Alternatively, the inflow channel resistance changing unit 50 may be driven together with the inflow amount changing unit 80 to reduce the pressure in the liquid chamber 30, or the volume changing unit 35 and the inflow channel resistance changing unit together with the inflow amount changing unit 80. 50 may be driven to reduce the pressure in the liquid chamber 30. Further, instead of the inflow amount changing unit 80, the volume changing unit 35 or the inflow path resistance changing unit 50 may be driven to reduce the pressure in the liquid chamber 30, or instead of the inflow amount changing unit 80. Alternatively, both the volume changing unit 35 and the inflow path resistance changing unit 50 may be driven to reduce the pressure in the liquid chamber 30. In the decompression process, the control unit 25 may drive at least one of the pressure transmission adjusting unit and the volume changing unit 35.

E11. Other embodiment 11:
In the first embodiment, the second embodiment, and the third embodiment, the control unit 25 increases the flow resistance of the inflow path 40 by the inflow path resistance changing unit 50 when the pressurizing process is performed. The transmission of pressure from the chamber 30 to the inflow path 40 is suppressed. On the other hand, the control unit 25 increases the flow resistance of the inflow path 40 in advance by the inflow path resistance changing unit 50 before starting the execution of the pressurizing process, so that the flow from the liquid chamber 30 to the inflow path 40 is increased. You may make it the state by which transmission of pressure is suppressed. In the fourth embodiment, the control unit 25, the inflow amount changing unit 80, and the inflow amount of the liquid LQ to the outflow passage 70 are reduced before the pressurization process is performed. The transmission of pressure to 40 is suppressed. On the other hand, the control unit 25 drives the inflow amount changing unit 80 together with the inflow channel resistance changing unit 50 during the pressurization process, and the transmission of pressure from the liquid chamber 30 to the inflow channel 40 is suppressed. You may be in a state to be. In the pressurization process, in a state where pressure transmission from the liquid chamber 30 to the flow path such as the inflow path 40 and the outflow path 70 is suppressed by the pressure transmission adjustment section such as the inflow path resistance change section 50 and the inflow amount change section 80. The operation of increasing the pressure of the liquid chamber 30 by the volume changing unit 35 may be executed.

E12. Other embodiment 12:
The present invention is not limited to a liquid ejecting apparatus that ejects ink, but can be applied to any liquid ejecting apparatus that ejects liquid other than ink. For example, the present invention is applicable to the following various liquid ejection devices.
(1) An image recording apparatus such as a facsimile apparatus.
(2) A color material discharge device used for manufacturing a color filter for an image display device such as a liquid crystal display.
(3) An electrode material discharge device used for electrode formation such as an organic EL (Electro Luminescence) display and a surface emission display (Field Emission Display, FED).
(4) A liquid ejection device that ejects a liquid containing a bio-organic material used for biochip manufacture.
(5) Sample discharge device as a precision pipette.
(6) A lubricating oil discharge device.
(7) Resin liquid discharge device.
(8) A liquid ejection device that ejects lubricating oil pinpoint to precision machines such as watches and cameras.
(9) A liquid ejection apparatus that ejects a transparent resin liquid such as an ultraviolet curable resin liquid onto a substrate in order to form a micro hemispherical lens (optical lens) used for an optical communication element or the like.
(10) A liquid discharge apparatus that discharges an acidic or alkaline etchant to etch a substrate or the like.
(11) A liquid discharge apparatus including a liquid discharge head that discharges another arbitrary minute amount of liquid droplets.

  In this specification, the “liquid” may be any material that can be consumed by the liquid ejection device. For example, the “liquid” may be a material in a state in which the substance is in a liquid phase, such as a material in a liquid state having high or low viscosity, and sol, gel water, other inorganic solvents, organic solvents, solutions, Liquid materials such as liquid resins and liquid metals (metal melts) are also included in the “liquid”. Further, “liquid” includes not only a liquid as one state of a substance but also a liquid obtained by dissolving, dispersing or mixing particles of a functional material made of a solid such as a pigment or metal particles in a solvent. Typical examples of the liquid include ink and liquid crystal. Here, the ink includes various liquid compositions such as general water-based ink and oil-based ink, gel ink, and hot-melt ink. The “droplet” refers to the state of the liquid ejected from the liquid ejecting apparatus, and includes those that have tails in the form of particles, tears, and threads.

E13. Other embodiment 13:
In the above embodiment, some or all of the functions and processes realized by software may be realized by hardware. In addition, some or all of the functions and processes realized by hardware may be realized by software. As the hardware, for example, various circuits such as an integrated circuit, a discrete circuit, or a circuit module combining these circuits can be used.

  The present invention is not limited to the above-described embodiments, examples, and modifications, and can be realized with various configurations without departing from the spirit thereof. For example, the technical features in the embodiments, examples, and modifications corresponding to the technical features in each embodiment described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the above effects, replacement or combination can be performed as appropriate. In addition, the technical features are not limited to those described in the specification as being essential, and if the technical features are not described as essential in the specification, they may be deleted as appropriate. Is possible.

  In each of the above embodiments, the liquid flow path included in the liquid ejection devices 100A to 100D includes at least the inflow path 40. In the fourth embodiment, the inflow path 40 and the outflow path 70 are included. Yes. The inflow path resistance changing unit 50 of the first embodiment, the second embodiment, and the third embodiment and the inflow amount changing unit 80 of the fourth embodiment are flow paths connected from the liquid chamber 30 to the liquid chamber 30. It is included in the pressure transmission adjustment unit that adjusts the transmission of pressure to

DESCRIPTION OF SYMBOLS 10 ... Tank, 15 ... Pressure adjustment part, 16 ... Supply path, 20A ... Head part, 20B ... Head part, 20C ... Head part, 20D ... Head part, 21 ... Case, 25 ... Control part, 30 ... Liquid chamber, 30 ... Inner wall surface, 31 ... Nozzle, 33 ... Communication port, 35 ... Volume changing part, 36 ... First drive chamber, 37 ... Diaphragm, 40 ... Inflow path, 41 ... Inlet, 43 ... Valve seat part, 50 ... Inflow Road resistance changing unit, 51 ... driving unit, 52 ... valve body, 53 ... second driving chamber, 54 ... through hole, 56 ... front end part, 57 ... rear end part, 60 ... pressure pump, 61 ... discharge path, 63 DESCRIPTION OF SYMBOLS ... Liquid storage part, 64 ... Negative pressure generation source, 65 ... Circulation path, 70 ... Outflow path, 71 ... Outlet, 73 ... Valve seat part, 80 ... Inflow amount change part, 81 ... Drive part, 82 ... Valve body, 83 ... Third drive chamber, 84 ... Through hole, 86 ... Front end, 87 ... Rear end, 100A ... Liquid ejection device, 10 B ... liquid discharge apparatus, 100C ... liquid discharge apparatus, 100D ... liquid discharge apparatus, DR ... droplets, LQ ... liquid, MP ... map, P ... pulse

Claims (6)

A liquid ejection device comprising:
A liquid chamber containing the liquid;
A flow path of the liquid connected to the liquid chamber, at least including a flow path for supplying the liquid to the liquid chamber;
A nozzle connected to the liquid chamber and discharging the liquid in the liquid chamber;
A volume changing section for changing the volume of the liquid chamber and discharging the liquid from the nozzle;
A pressure transmission adjustment unit that controls the inflow of the liquid from the liquid chamber to the flow path and adjusts the transmission of pressure from the liquid chamber to the flow path;
A control unit for controlling the volume changing unit and the pressure transmission adjusting unit to discharge the liquid from the nozzle;
With
The controller is
In a state where the pressure transmission adjustment unit suppresses the pressure transmission from the liquid chamber to the flow path, the volume changing unit reduces the volume of the liquid chamber to increase the pressure of the liquid chamber, A pressurizing process for starting the outflow of the liquid from the nozzle;
After the pressurizing process is performed, when the predetermined elapsed time has elapsed while the liquid is flowing out from the nozzle, at least one of the pressure transmission adjusting unit and the volume changing unit is driven. By reducing the pressure of the liquid chamber, the pressure reduction process for separating and flying droplets from the liquid of the nozzle,
A discharge amount control process for determining the elapsed time according to a target discharge amount of the liquid before the execution of the pressure reduction process;
Performing the liquid ejection device. The liquid ejection device according to claim 1,
The pressure transmission adjusting unit is an inflow path resistance changing unit that adjusts inflow of the liquid from the liquid chamber to the inflow path by changing a flow path resistance of the inflow path.
The pressurizing process is performed in a state where the flow path resistance of the inflow path is increased by the inflow path resistance changing unit and the transmission of pressure from the liquid chamber to the inflow path is suppressed,
The decompression process is performed by reducing the flow path resistance of the inflow path from the liquid chamber to the inflow path while the volume change section is reducing the volume of the liquid chamber. And by reducing the pressure of the liquid chamber by promoting the escape of pressure,
The elapsed time is the operation in which the inflow path resistance changing unit reduces the flow path resistance of the inflow path in the decompression process after the volume changing unit reduces the volume of the liquid chamber in the pressurizing process. The liquid ejection device, which is the time between The liquid ejection device according to claim 1,
The pressure transmission adjusting unit is an inflow path resistance changing unit that adjusts the transmission of pressure from the liquid chamber to the inflow path by changing the flow path resistance of the inflow path,
The pressurizing process is performed in a state where the flow path resistance of the inflow path is increased by the inflow path resistance changing unit and the transmission of pressure from the liquid chamber to the inflow path is suppressed,
The depressurization process is a process for reducing the pressure of the liquid chamber by increasing the volume of the liquid chamber in the volume changing unit while the pressure of the liquid chamber is higher than the pressure before the pressurization process. And
The elapsed time is a period of time from when the volume changing unit reduces the volume of the liquid chamber in the pressurizing process until the volume changing unit starts to increase the volume of the liquid chamber in the depressurizing process. A liquid ejection device. The liquid ejection device according to claim 1,
The flow path further includes an outflow path for discharging the liquid in the liquid chamber,
The pressure transmission adjustment unit is an inflow amount changing unit that changes the inflow amount of the liquid from the liquid chamber to the outflow passage and adjusts the transmission of pressure from the liquid chamber to the outflow passage,
The pressurizing process is executed in a state where the inflow amount of the liquid to the outflow passage is reduced by the inflow amount changing section and the transmission of pressure from the liquid chamber to the outflow passage is suppressed,
In the decompression process, while the volume of the liquid chamber is reduced by the volume changing unit, the inflow amount changing unit increases the inflow amount of the liquid into the outflow path. A process to reduce the pressure,
The elapsed time is an operation in which the inflow amount changing unit increases the inflow amount of the liquid into the outflow passage in the depressurization process after the volume changing unit reduces the volume of the liquid chamber in the pressurizing process. The liquid ejection device, which is the time until the start of The liquid ejection device according to any one of claims 1 to 4,
When the flow resistance from the inflow path to the nozzle is R, the inertance from the inflow path to the nozzle is M, and the compliance from the inflow path to the nozzle is C, √ (M / C) <R / 2, the liquid ejection device satisfying the relationship. A method for controlling a liquid ejection device, comprising:
In a state where the transmission of pressure to the liquid flow path connected to the liquid chamber containing the liquid is suppressed, the pressure of the liquid chamber is increased and the liquid communicates from the nozzle communicating with the liquid chamber. A pressurizing step for starting the outflow of
The pressure of the liquid chamber is determined when a predetermined elapsed time elapses while the liquid flows out of the nozzle after the liquid starts flowing out of the nozzle by the pressurizing step. Reducing pressure, separating the liquid droplets from the liquid of the nozzle and flying,
A discharge amount control step of determining the elapsed time according to a target discharge amount of the liquid before the pressure reducing step;
A control method comprising:

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