Head unit, liquid dispensing device, coating device, drive device, and drive method

Abstract

To reduce a discharge failure of liquid caused by air bubbles entrained into a nozzle hole for discharging liquid.SOLUTION: A head unit includes: a liquid discharge head which has a liquid chamber for storing pressurized liquid, a nozzle hole for discharging the liquid, a valve element provided in the liquid chamber, and a driving body for moving the valve element to a position where the valve element closes the nozzle hole and a position where the valve element opens the nozzle hole; and a drive control section which applies an open voltage for moving the valve element to the position where the nozzle hole is opened and a closed voltage for moving the valve element to the position where the nozzle hole is closed to the driving body. A signal waveform of the open voltage has a first period when a first voltage is applied and a second period when a second voltage different from the first voltage is applied after the first period.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a head unit, a liquid ejection device, a coating device, a drive device, and a drive method.

Background Art

[0002] Patent Document 1 describes a paint injection nozzle including a nozzle hole for injecting paint, a paint chamber that supplies paint to the nozzle hole, a needle valve disposed inside the paint chamber and configured to close or open the nozzle hole at a tip end thereof, and a drive mechanism that causes the needle valve to advance and retract, wherein when the needle valve opens the nozzle hole, the needle valve is retracted at a speed higher than the deformation recovery speed of a synthetic resin layer formed at the tip of the needle valve.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when the retraction speed of the needle valve is increased, the vibration of the needle valve caused by the opening of the needle valve becomes large, and there is a problem that bubbles are entrained from the nozzle hole due to the vibration, leading to liquid ejection failure.

Means for Solving the Problems

[0005] The present invention relates to a head unit comprising: a liquid discharge head having a liquid chamber for containing pressurized liquid; a nozzle hole for discharging the liquid; a valve body provided in the liquid chamber; and a drive body for moving the valve body to a position where the valve body closes the nozzle hole and a position where the valve body opens the nozzle hole; and a drive control unit for applying an opening voltage to the drive body to move the valve body to a position where the nozzle hole is open and a closing voltage to move the valve body to a position where the nozzle hole is closed, wherein the signal waveform of the opening voltage has a first period for applying a first voltage and a second period after the first period for applying a second voltage different from the first voltage. The second voltage is the voltage between the closing voltage and the first voltage, the valve body vibrates at a natural vibration period in the direction of movement of the valve body when the nozzle hole is open, and the second period is shorter than half of the natural vibration period. It is characterized by the following. [Effects of the Invention]

[0006] According to the present invention, it is possible to reduce liquid discharge failures caused by air bubbles being trapped in the nozzle holes for discharging liquid. [Brief explanation of the drawing]

[0007] [Figure 1] A cross-sectional view showing an example of a head unit according to the embodiment. [Figure 2] An explanatory diagram showing an example of a pressurizing mechanism and a moving mechanism. [Figure 3] A block diagram showing an example of the control system for the head unit, pressurizing mechanism, and moving mechanism. [Figure 4] Diagram illustrating the opening and closing operation of the nozzle hole. [Figure 5] An explanatory diagram showing the relationship between the drive signal and needle displacement in a comparative example. [Figure 6] An explanatory diagram showing the relationship between the drive signal and the needle displacement in the first embodiment. [Figure 7] An explanatory diagram showing the relationship between the drive signal and the needle displacement in the second embodiment. [Figure 8] An explanatory diagram showing the relationship between the drive signal and the needle displacement in the third embodiment. [Figure 9] An explanatory diagram showing the relationship between the drive signal and the needle displacement in the fourth embodiment. [Figure 10]An explanatory diagram showing the relationship between the drive signal and the needle displacement in the fifth embodiment. [Figure 11] A cross-sectional view showing another configuration example of the head unit according to the embodiment. [Figure 12] An explanatory diagram showing an example of a method for measuring the natural vibration period. [Figure 13] An explanatory diagram showing an example of a coating apparatus. [Figure 14] An explanatory diagram showing an example of how to use the coating device. [Figure 15] An explanatory diagram showing an example of an electrode manufacturing apparatus. [Figure 16] An explanatory diagram showing an example of its application. [Modes for carrying out the invention]

[0008] The embodiments for carrying out the invention will be described below with reference to the drawings. In the description of the drawings, the same elements will be denoted by the same reference numeral, and redundant explanations will be omitted.

[0009] [Head unit configuration] First, the configuration of the head unit according to the embodiment will be described with reference to Figure 1. Figure 1 is a cross-sectional view showing an example of the head unit according to the embodiment.

[0010] The head unit illustrated in Figure 1 is an inkjet head unit that ejects ink, which is an example of a liquid. The inkjet head unit HU (hereinafter referred to as the head unit) consists of an inkjet head 100 (hereinafter referred to as the head), which is an example of a liquid ejection head, and a drive control unit 500 that controls the drive of the head 100. The drive control unit 500 is also an example of a drive device. The head 100 comprises a hollow housing 110 and a nozzle plate 101 provided at one end of the housing 110. The nozzle plate 101 is a plate-shaped member in which nozzle holes 102 for ejecting ink 10 are formed.

[0011] The housing 110 includes an injection port 113 for injecting ink 10 on the side surface close to the nozzle hole 102. The ink 10 injected from the injection port 113 is stored in the liquid chamber 114 inside the housing 110. The liquid chamber 114 is generally formed by a space formed between the nozzle plate 101 and a sealing member 135 provided inside the housing 110.

[0012] Inside the liquid chamber 114, a needle 131 which is an example of a valve element is provided. A valve member 130 is joined to the tip end portion of the needle 131 on the side where the nozzle plate 101 is positioned so as to face the nozzle hole 102. The valve member 130 is made of an elastic body such as rubber. By providing the valve member 130 at the tip end portion of the needle 131, the adhesion to the nozzle hole 102 is improved, and the nozzle hole 102 can be closed more reliably. Note that the configuration of the needle 131 is not limited to the above. For example, a configuration in which the nozzle hole 102 is directly closed by the tip end portion of the needle 131 without providing the valve member 130 may be adopted.

[0013] The sealing member 135 is made of an elastic body such as rubber. In the present embodiment, a rubber O-ring is used as the sealing member 135, and the O-ring is fitted to the needle 131 so as to seal the gap between the inner surface of the housing 110 and the outer peripheral surface of the needle 131. Thereby, the sealing member 135 prevents the ink 10 in the liquid chamber 114 from flowing toward the piezoelectric element 132 side.

[0014] One example of a drive unit, the piezoelectric element 132, is provided in a space formed next to the liquid chamber 114 (above in Figure 1), separated by the sealing member 135. The piezoelectric element 132 moves the needle 131 between a position that closes the nozzle hole 102 and a position that opens the nozzle hole 102, in response to a drive signal from the drive control unit 500. In the position that closes the nozzle hole 102, the valve member 130 is in contact with the nozzle plate 101, and in the position that opens the nozzle hole 102, the valve member 130 is separated from the nozzle plate 101. In the case of a configuration without a valve member 130, in the position that closes the nozzle hole 102, the needle 131 is in contact with the nozzle plate 101, and in the position that opens the nozzle hole 102, the needle 131 is separated from the nozzle plate 101.

[0015] The piezoelectric element 132 is a piezoelectric element formed using zirconia ceramics or the like, and the shape of the piezoelectric element 132 is appropriately set according to the amount of ink droplets to be ejected.

[0016] The drive control unit 500 is electrically connected to the piezoelectric element 132 and controls the driving of the piezoelectric element 132.

[0017] [Configuration of the pressurizing mechanism and the moving mechanism] Next, the pressurizing mechanism that supplies ink 10 to the head 100 under pressure, and the moving mechanism that moves the head 100 relative to the object will be described using Figures 2 and 3. Figure 2 is an explanatory diagram showing an example of the pressurizing mechanism and the moving mechanism, and Figure 3 is a block diagram showing an example of the control system for the head unit, pressurizing mechanism and moving mechanism.

[0018] In Figure 2, the ink 10 ejected from the print head 100 is contained in a sealed ink tank 202. The ink tank 202 and the ink inlet 113 of the print head 100 are connected by a tube 201.

[0019] The ink tank 202 is connected to the compressor 205 via a pipe 203 that includes an air regulator 204. The air regulator 204 adjusts the pressure of the compressed air created by the compressor 205 to the required air pressure and supplies pressurized air from the compressor 205 to the ink tank 202. As a result, pressurized ink 10 is supplied to the liquid chamber 114 of the print head 100, and the valve member 130 separates from the nozzle plate 101, allowing the liquid chamber 114 and the nozzle hole 102 to communicate, and the ink 10 is discharged from the nozzle hole 102. Here, the tube 201, ink tank 202, pipe 203, air regulator 204, and compressor 205 constitute a pressurizing mechanism 200 for supplying pressurized ink 10 to the liquid chamber 114 of the print head 100. The pressurizing mechanism 200 is an example of a pressurizing means.

[0020] Furthermore, a portion of the housing 110 of the head 100 (the upper part in Figure 2) is held by the head holding member 301. The head holding member 301 is connected to a drive unit 302, and by driving the drive unit 302, the head holding member 301 can move along the rail member 303 in the directions of arrows A and B. As a result, the head 100 held by the head holding member 301 also moves along the rail member 303 in the directions of arrows A and B. Here, the head holding member 301, the drive unit 302, and the rail member 303 constitute a head moving mechanism 300 for moving the head 100 relative to an object. The head moving mechanism 300 is an example of a moving means.

[0021] The drive unit 302 and rail member 303 may be appropriately configured using well-known mechanisms such as a feed screw mechanism using a ball screw, a feed mechanism using a rack and pinion, or a feed mechanism using a power transmission belt and pulley.

[0022] Here, the head unit HU (head 100, drive control unit 500) connected to the pressurizing mechanism 200 and the head moving mechanism 300 is an example of a liquid dispensing device.

[0023] As shown in Figure 3, the head unit HU, the pressurizing mechanism 200, and the head moving mechanism 300 are electrically connected to the control unit 600. The control unit 600 may, for example, control the overall operation of the coating apparatus described later, and additional components may be added as needed, in addition to the components shown in Figure 3.

[0024] The control unit 600 transmits, for example, an ink ejection cycle signal based on image data to the drive control unit 500 of the head unit HU. The control unit 600 receives status information of the head 100, etc., via the drive control unit 500. The control unit 600 also transmits a switching signal to the pressurizing mechanism 200 to switch the pressurization on and off. Furthermore, the control unit 600 transmits a movement signal to the head moving mechanism 300 to move the head 100.

[0025] The drive control unit 500 of the head unit HU includes an input unit 501, a drive voltage generation unit 502, an amplification unit 503, and an output unit 504.

[0026] The input unit 501 receives ink ejection cycle signals and the like based on image data from the control unit 600.

[0027] The drive voltage generation unit 502 generates a drive voltage to drive the piezoelectric element 132 of the head 100 in accordance with information such as the ink ejection cycle signal received by the input unit 501.

[0028] The amplification unit 503 amplifies the drive voltage generated by the drive voltage generation unit 502 and outputs the amplified signal to the output unit 504.

[0029] The output unit 504 applies a drive voltage to the piezoelectric element 132 based on the signal amplified by the amplification unit 503.

[0030] Each of the functions, such as the input unit 501, the drive voltage generation unit 502, the amplification unit 503, and the output unit 504, can be implemented by electrical circuits, or some of these functions can be implemented by software (CPU: Central Processing Unit). Furthermore, each of the above functions may be implemented by multiple circuits or multiple software programs.

[0031] As described above, the drive control unit 500 generates a drive signal based on the ink ejection cycle signal received from the control unit 600, and drives the head 100 using the generated drive signal. The head 100 opens and closes the nozzle holes 102 in response to the drive signal from the drive control unit 500 and ejects ink.

[0032] The pressurizing mechanism 200 switches the compressor 205 (or air regulator 204) on and off based on a switching signal received from the control unit 600, thereby switching the ink 10 sent to the liquid chamber 114 between a pressurized state and an unpressurized state.

[0033] Based on a movement signal received from the control unit 600, the head movement mechanism 300 drives the drive unit 302 in a predetermined direction by a predetermined distance, moving the head 100 to a desired position via the head holding member 301.

[0034] [Regarding the opening and closing operation of the nozzle holes] Next, we will explain the opening and closing operation of the nozzle hole using Figure 4.

[0035] When a drive voltage is applied to the piezoelectric element 132 from the drive control unit 500, and a closing voltage is applied to the piezoelectric element 132, the valve member 130 is in contact with the nozzle plate 101, as shown in Figure 4(a), and the valve member 130 closes the nozzle hole 102. Therefore, the ink 10 in the liquid chamber 114 is not ejected from the nozzle hole 102.

[0036] When an open-circuit voltage is applied to the piezoelectric element 132, as shown in Figure 4(b), the piezoelectric element 132 contracts, causing the needle 131 to move upward in the figure. This movement of the needle 131 causes the valve member 130, which is joined to the needle 131, to move away from the nozzle plate 101, and a gap G is formed between the tip of the valve member 130 and the nozzle hole 102. Since the ink 10 in the liquid chamber 114 is supplied under pressure at a predetermined pressure by the pressurization mechanism 200, as the gap G is formed, the ink 10 in the liquid chamber 114 is ejected from the nozzle hole 102 as ink droplets 10'.

[0037] In this manner, when a driving voltage (closing voltage, opening voltage) is applied to the piezoelectric element 132, the valve member 130 moves between a position in contact with the nozzle plate 101 and a position separated from it (in the direction of arrow C in Figure 4(b)), and the valve member 130 opens and closes the nozzle hole 102.

[0038] [Drive signal] The relationship between the drive signal output from the drive control unit 500 and the operation of the needle 131 provided by the head 100 will be explained below with reference to Figures 5 to 10. Figures 5 to 10 are explanatory diagrams showing the relationship between the drive signal and the displacement of the needle, with Figure 5 being a comparative example and Figures 6 to 10 being embodiments based on the present invention.

[0039] <Comparative Example> In the comparative example, the drive signal is a square wave defined by a closing voltage E1 and an open voltage E2, as shown in Figure 5(a). Here, the closing voltage refers to the drive voltage applied to the piezoelectric element 132 when moving the needle 131 to the position that closes the nozzle hole 102. The open voltage refers to the drive voltage applied to the piezoelectric element 132 when moving the needle 131 to the position that opens the nozzle hole 102.

[0040] When an open-circuit voltage E2 is applied to the piezoelectric element 132, the piezoelectric element 132 contracts, and as a result of this contraction, the needle 131 is displaced from position P1 to position P2 as shown in Figure 5(b). That is, the needle 131 moves in a direction that separates the valve member 130 from the nozzle plate 101 based on the drive signal. When the valve member 130 is separated from the nozzle plate 101 and a gap G is formed between the valve member 130 and the nozzle hole 102 as shown in Figure 4(b), the ink 10 in the liquid chamber 114 becomes ready to be ejected from the nozzle hole 102. However, in reality, as shown in Figure 5, when an open-circuit voltage E2 is applied to the piezoelectric element 132, the needle 131 vibrates at its natural vibration period T, leading to the following ejection failure.

[0041] In other words, because the displacement of the needle 131 from position P1 to position P2 based on the application of the open-circuit voltage E2 to the piezoelectric element 132 is steep, if the pressure applied from the pressurizing mechanism 200 to the liquid chamber 114 is not fast enough, the pressure inside the liquid chamber 114 fluctuates along with the displacement of the needle 131. As a result, during the process of the needle 131 moving from position P1 to position P2 (the section labeled "bubble entrapment 1" in Figure 5(b)), bubbles are entrapped (sucked) into the liquid chamber 114 from the nozzle hole 102.

[0042] The bubbles trapped in the liquid chamber 114 are pushed out when pressure is applied to the liquid chamber 114 from the pressurizing mechanism 200, and are gradually discharged out of the liquid chamber 114 through the nozzle hole 102 (corresponding to the "bubble discharge" section in Figure 5(b)).

[0043] However, during the period t1 when the open-circuit voltage E2 is applied to the piezoelectric element 132, the needle 131 vibrates at its natural vibration period T, causing the pressure inside the liquid chamber 114 to fluctuate in sync with the natural vibration period T of the needle 131. As a result, as shown in the "bubble entrapment 2" section of Figure 5(b), when the needle 131 is displaced again towards position P2, bubbles are again entrapped into the liquid chamber 114 from the nozzle hole 102.

[0044] After time t1, when a closing voltage E1 is applied to the piezoelectric element 132, the piezoelectric element 132 extends, and as it extends, the needle 131 is displaced to position P1, as shown in the "droplet ejection" section of Figure 5(b). That is, the needle 131 moves in a direction that brings the valve member 130 into contact with the nozzle plate 101 based on the drive signal. Then, during the process until the needle 131 reaches position P1 (the "droplet ejection" section of Figure 5(b)), the ink 10 in the liquid chamber 114 is ejected from the nozzle hole 102 as an ink droplet 10'.

[0045] As described above, the comparative example re-introduces air bubbles that have been discharged from the liquid chamber, resulting in droplets containing air bubbles being ejected from the nozzle hole, thus failing to achieve the desired liquid discharge.

[0046] <First Embodiment> Next, the first embodiment will be described using Figure 6. Figure 6 is an explanatory diagram showing the relationship between the drive signal and the needle displacement in the first embodiment.

[0047] The drive signal in the first embodiment is a stepped waveform defined by a closing voltage E1 and two types of open voltages E2 and E3, as shown in Figure 6(a). The closing voltage refers to the drive voltage applied to the piezoelectric element 132 when moving the needle 131 to the position that closes the nozzle hole 102. The open voltage refers to the drive voltage applied to the piezoelectric element 132 when moving the needle 131 to the position that opens the nozzle hole 102.

[0048] The open-circuit voltage E2 is set to a different value from the open-circuit voltage E3 (a smaller value than the open-circuit voltage E3 in this embodiment). First, the open-circuit voltage E3 is applied to the piezoelectric element 132 for a period of time t1, and then the open-circuit voltage E2 is applied to the piezoelectric element 132 for a period of time t2. In the first embodiment, the open-circuit voltage E3 is an example of a "first voltage," and the open-circuit voltage E2 is an example of a "second voltage." Also, the period of time t1 during which the open-circuit voltage E3 is applied is an example of a "first period," and the period of time t2 during which the open-circuit voltage E2 is applied is an example of a "second period."

[0049] In the first embodiment, when the first voltage, the open-circuit voltage E3, is applied to the piezoelectric element 132, the piezoelectric element 132 contracts, and as a result of this contraction, the needle 131 is displaced from position P1 to position P2 as shown in Figure 6(b). That is, the needle 131 moves in a direction that separates the valve member 130 from the nozzle plate 101 based on the drive signal. Similar to the comparative example, the displacement of the needle 131 from position P1 to position P2 at this time is steep, so if the pressure applied from the pressurizing mechanism 200 to the liquid chamber 114 is not fast enough, the pressure inside the liquid chamber 114 fluctuates along with the displacement of the needle 131. As a result, during the process of the needle 131 moving from position P1 to position P2 (the "bubble entrapment" section in Figure 6(b)), bubbles are entrapped (sucked in) from the nozzle hole 102 into the liquid chamber 114.

[0050] The bubbles trapped in the liquid chamber 114 are pushed out when pressure is applied to the liquid chamber 114 from the pressurizing mechanism 200, and are gradually discharged out of the liquid chamber 114 through the nozzle hole 102 (corresponding to the section labeled "bubble discharge 1" in Figure 6(b)).

[0051] Next, at the moment when the needle 131 begins to displace again toward position P2 due to its natural vibration period T, the drive control unit 500 applies a second voltage, the open-circuit voltage E2, to the piezoelectric element 132. The application of the open-circuit voltage E2 causes the piezoelectric element 132 to extend, and as it extends, the needle 131 moves in a direction that moves the valve member 130 toward the nozzle plate 101, and the displacement of the needle 131 toward position P2 is suppressed, as shown in the "bubble discharge 2" section of Figure 6(b).

[0052] After time t2, when a closing voltage E1 is applied to the piezoelectric element 132, the piezoelectric element 132 extends, and as it extends, the needle 131 is displaced to position P1, as shown in the "droplet ejection" section of Figure 6(b). That is, the needle 131 moves in a direction that brings the valve member 130 into contact with the nozzle plate 101 based on the drive signal. Then, during the process until the needle 131 reaches position P1 (the "droplet ejection" section of Figure 6(b)), the ink 10 in the liquid chamber 114 is ejected from the nozzle hole 102 as an ink droplet 10'.

[0053] As described above, according to the first embodiment, re-entrainment of air bubbles from the nozzle holes can be prevented. In the case of the first embodiment, as shown in FIG. 6(b), the peak values after "air bubble discharge 2" are suppressed to low values, and the needle 131 (valve member 130) is positioned on the side closer to the nozzle plate 101. However, since no air bubbles are contained in the liquid chamber 114, the liquid discharge amount can be ensured.

[0054] As an example of the first embodiment, when the natural vibration period of the needle 131 is defined as T, the time t1 is specified to satisfy the relationship of T<t1<3 / 2T, and the time t2 is specified to satisfy the relationship of t2<1 / 2T. Thereby, the vibration of the needle 131 can be efficiently suppressed at a timing slightly delayed after the start of transition from "air bubble discharge 1" to "air bubble discharge 2" in FIG. 6(b), and liquid can be efficiently discharged at the timing when "air bubble discharge 2" ends. Further, the open voltage E2 is specified to satisfy the relationship of 1 / 2E3<E2<E3 with respect to the open voltage E3.

[0055] As described above, the present embodiment is a head unit HU including: a head 100 having a liquid chamber 114 that stores pressurized ink 10, a nozzle hole 102 that discharges the ink 10, a needle 131 provided in the liquid chamber 114, and a piezoelectric element 132 that moves the needle 131 to a position where the needle 131 closes the nozzle hole 102 and a position where the needle 131 opens the nozzle hole 102; and a drive control unit 500 that applies an open voltage for moving the needle 131 to the position where the nozzle hole 102 is opened and a closing voltage for moving the needle 131 to the position where the nozzle hole 102 is closed to the piezoelectric element 132, wherein the signal waveform of the open voltage has a time t1 during which the open voltage E3 is applied, and a time t2 during which the open voltage E2 different from the open voltage E3 is applied after the time t1.

[0056] Further, as described above, the open voltage E2 is provided to be a voltage between the closing voltage E1 and the open voltage E3.

[0057] Furthermore, as described above, when the nozzle hole 102 is open, the needle 131 vibrates with a natural vibration period T in the direction of movement of the needle 131, and time t2 is shorter than half of the natural vibration period T.

[0058] Furthermore, when the nozzle hole 102 is open, the needle 131 vibrates with a natural period T in the direction of movement of the needle 131, and time t1 is longer than the natural period T and shorter than 3 / 2 of the natural period T.

[0059] As a result, when an open-circuit voltage E2 is applied to the piezoelectric element 132, it is possible to prevent air bubbles from being drawn in and to prevent unintended discharge.

[0060] <Second Embodiment> Next, a second embodiment will be described using Figure 7. Figure 7 is an explanatory diagram showing the relationship between the drive signal and the needle displacement in the second embodiment.

[0061] In the second embodiment, the drive signal is a stepped waveform defined by a closed voltage E1 and two open voltages E2 and E3, as shown in Figure 7(a). The definitions of the closed voltage and open voltage are the same as in the first embodiment.

[0062] The open-circuit voltage E2 is set to a different value from the open-circuit voltage E3 (a smaller value than the open-circuit voltage E3 in this embodiment). First, the open-circuit voltage E2 is applied to the piezoelectric element 132 for a period of time t1, and then the open-circuit voltage E3 is applied to the piezoelectric element 132 for a period of time t2. In the second embodiment, the open-circuit voltage E2 is an example of the "first voltage," and the open-circuit voltage E3 is an example of the "second voltage." Also, the period of time t1 during which the open-circuit voltage E2 is applied is an example of the "first period," and the period of time t2 during which the open-circuit voltage E3 is applied is an example of the "second period."

[0063] In the second embodiment, when the first voltage, which is the open-circuit voltage E2, is applied to the piezoelectric element 132, the piezoelectric element 132 contracts, and as it contracts, the needle 131 is displaced from position P1 to position P2 as shown in Figure 7(b). That is, the needle 131 moves in a direction that separates the valve member 130 from the nozzle plate 101 based on the drive signal. For the same reasons as in the comparative example and the first embodiment, during the process in which the needle 131 moves from position P1 to position P2 (the "bubble entrapment" section in Figure 7(b)), bubbles are entrapped into the liquid chamber 114 from the nozzle hole 102.

[0064] Next, at the moment when the needle 131 begins to displace from position P2 towards position P1 due to its natural vibration period T, the drive control unit 500 applies a second voltage, the open-circuit voltage E3, to the piezoelectric element 132. Applying the open-circuit voltage E3 to the piezoelectric element 132 causes it to contract further, and as it contracts, the needle 131 also moves to position P3, which is further away from the nozzle plate 101. This increases the volume of the discharged droplet.

[0065] As described above, in the second embodiment, when the needle 131 begins to displace from position P2 towards position P1, the needle 131 is moved further away from the nozzle plate 101, making it possible to maintain the needle 131 at approximately position P2. Then, in the "bubble discharge" section of Figure 7(b), the needle 131 is almost stationary near position P3, so the bubbles trapped in the liquid chamber 114 are gradually discharged by the pressure applied to the liquid chamber 114 from the pressurizing mechanism 200.

[0066] Furthermore, in the second embodiment, the displacement of the needle 131 immediately before droplet ejection is large, which allows for a larger droplet volume.

[0067] As an example of the second embodiment, when the natural vibration period of the needle 131 is T, the time t1 is defined to satisfy the relationship of 1 / 2T<t1<T, and the time t2 is defined to satisfy the relationship of 1 / 2T<t2<T. Thereby, the vibration of the needle 131 can be efficiently suppressed at the timing when the needle 131 starts to displace from the position P2 toward the position P1 side, and the liquid can be efficiently discharged at the timing when "bubble discharge" is completed. Further, with respect to the release voltage E2, the release voltage E3 is defined to satisfy the relationship of E2<E3<4 / 3E2. Thereby, when the release voltage E3 is applied to the piezoelectric element 132, the volume of the liquid droplet can be increased without entraining air bubbles and while preventing unintended discharge.

[0068] As described above, in the present embodiment, the release voltage E2 is a voltage between the closing voltage E1 and the release voltage E3.

[0069] Further, as described above, at the position where the nozzle hole 102 is opened, the needle 131 vibrates at the natural vibration period T in the moving direction of the needle 131, and the time t1 is longer than half of the natural vibration period T and shorter than the natural vibration period T.

[0070] Thereby, when the release voltage E3 is applied to the piezoelectric element 132, it is possible to prevent entrainment of air bubbles and unintended discharge.

[0071] <Third Embodiment> Next, the third embodiment will be described with reference to FIG. 8. FIG. 8 is an explanatory diagram showing the relationship between the drive signal and the displacement of the needle in the third embodiment.

[0072] The drive signal in the third embodiment is a stepped waveform defined by the closing voltage E1 and two types of release voltages E2 and E3 as shown in FIG. 8(a). The definitions of the closing voltage and the release voltage are the same as those in the first embodiment.

[0073] The open-circuit voltage E2 is set to a different value from the open-circuit voltage E3 (a smaller value than the open-circuit voltage E3 in this embodiment). First, the open-circuit voltage E2 is applied to the piezoelectric element 132 for a period of time t1, and then the open-circuit voltage E3 is applied to the piezoelectric element 132 for a period of time t2. In the third embodiment, the open-circuit voltage E2 is an example of a "first voltage," and the open-circuit voltage E3 is an example of a "second voltage." Also, the period of time t1 during which the open-circuit voltage E2 is applied is an example of a "first period," and the period of time t2 during which the open-circuit voltage E3 is applied is an example of a "second period."

[0074] In the third embodiment, when the first voltage, the open-circuit voltage E2, is applied to the piezoelectric element 132, the piezoelectric element 132 contracts, and as a result of this contraction, the needle 131 is displaced from position P1 to position P2 as shown in Figure 8(b). That is, the needle 131 moves in a direction that separates the valve member 130 from the nozzle plate 101 based on the drive signal. For the same reasons as in the comparative example and the first embodiment, during the process in which the needle 131 moves from position P1 to position P2 (the section labeled "bubble entrapment 1" in Figure 8(b)), bubbles are entrapped into the liquid chamber 114 from the nozzle hole 102.

[0075] Next, at the moment when the needle 131 begins to displace from position P2 towards position P1 (the moment when it begins to move into the "bubble discharge 1" section in Figure 8(b)), a second voltage, the open-circuit voltage E3, is applied to the piezoelectric element 132. Since the open-circuit voltage E3 is a larger value than the open-circuit voltage E3 in the second embodiment, the needle 131 is moved to position P3, which is further away from the nozzle plate 101. This makes it possible to increase the volume of the discharged droplet compared to the second embodiment.

[0076] During the process of the needle 131 moving from position P2 to position P3 (the "bubble entrapment 2" section in Figure 8(b)), bubbles are entrapped into the liquid chamber 114 from the nozzle hole 102, but these bubbles are discharged in the next "bubble discharge 2" section. Time t2 is set to be sufficient time for the bubbles to be discharged from the liquid chamber 114 by the pressure applied by the pressurizing mechanism 200.

[0077] As an example of the third embodiment, when the natural vibration period of the needle 131 is T, the time t1 is defined so as to satisfy the relationship of 1 / 2T<t1<T, and the time t2 is defined so as to satisfy the relationship of T<t2. Thereby, the vibration of the needle 131 can be efficiently suppressed at the timing when the needle 131 starts to displace from the position P2 toward the position P1 side, and the liquid can be discharged in a state where air bubbles are discharged at the timing when "air bubble discharge 2" ends. Further, the open-circuit voltage E3 is defined so as to satisfy the relationship of 4 / 3E2<E3<3 / 2E2 with respect to the open-circuit voltage E2. Thereby, the volume of the liquid droplet can be further increased while preventing unintended discharge.

[0078] As described above, in the first to third embodiments, the configuration has been described in which the needle 131 displaced to the position P2 based on the open-circuit voltage suppresses or amplifies the vibration of the needle 131 at the timing when the needle 131 starts to displace toward the position P1 side according to its own natural vibration period, so as to discharge air bubbles.

[0079] The fourth and fifth embodiments described below are intended to suppress the vibration of the needle 131 at the time of rising when an open-circuit voltage is applied to the piezoelectric element 132, and reduce the suction of air bubbles at the time of rising.

[0080] <Fourth Embodiment> The fourth embodiment will be described with reference to FIG. 9. FIG. 9 is an explanatory diagram showing the relationship between the drive signal and the displacement of the needle in the fourth embodiment.

[0081] The drive signal in the fourth embodiment is a stepped waveform defined by the closing voltage E1 and two types of open-circuit voltages Em and E2, as shown in FIG. 9(a). The definitions of the closing voltage and the open-circuit voltage are the same as in the above-described embodiments.

[0082] The open-circuit voltage Em is set to a value different from the open-circuit voltage E2 (in the present embodiment, a value smaller than the open-circuit voltage E2). First, the open-circuit voltage Em is applied to the piezoelectric element 132 for a period of time t1, and then the open-circuit voltage E2 is applied to the piezoelectric element 132 for a period of time t2. In the fourth embodiment, the open-circuit voltage Em is an example of a "first voltage", and the open-circuit voltage E2 is an example of a "second voltage". Further, the period of time t1 during which the open-circuit voltage Em is applied is an example of a "first period", and the period of time t2 during which the open-circuit voltage E2 is applied is an example of a "second period".

[0083] In the fourth embodiment, the needle 131 is not displaced all at once from the position P1 to the position P2, but a period for maintaining the position Pm as shown in Fig. 9(b) is provided on the way. Thereby, rapid pressure fluctuations in the liquid chamber 114 can be suppressed. In addition, since the vibration of the needle 131 becomes gentle, the entrainment of air bubbles into the liquid chamber 114 can be reduced, and heat generation of the piezoelectric element 132 can be reduced.

[0084] Note that, in the needle 131 after reaching the position P2, there is a possibility that air bubbles are entrained again due to vibration at the natural vibration period T of the needle 131. However, if a needle with a small free vibration amplitude is used, the amount of air bubbles entrained again is small, and the present configuration is effective.

[0085] As an example of the fourth embodiment, when the natural vibration period of the needle 131 is T, the time t1 is defined to satisfy the relationship t1<1 / 2T, and the time t2 is defined to satisfy the relationship T<t2<3 / 2T. Thereby, the needle 131 is temporarily stagnated near the position Pm in the middle of being displaced toward the position P2, so that entrainment of air bubbles can be suppressed, and at the timing when "air bubble discharge 2" ends, liquid can be discharged in a state where air bubbles have been discharged. Further, the open-circuit voltage Em is defined to satisfy the relationship 2 / 3E2<Em<E2 with respect to the open-circuit voltage E2.

[0086] As described above, in this embodiment, the needle 131 vibrates at a natural vibration period T in the direction of movement of the needle 131 when the nozzle hole 102 is open, and time t1 is shorter than half of the natural vibration period T.

[0087] Furthermore, as described above, when the nozzle hole 102 is open, the needle 131 vibrates with a natural vibration period T in the direction of movement of the needle 131, and time t2 is longer than half of the natural vibration period T.

[0088] Furthermore, as described above, the open-circuit voltage Em is set to be a voltage between the closed-circuit voltage E1 and the open-circuit voltage E2.

[0089] This allows the displacement of the needle 131 and the entrapment of air bubbles to be almost completed in the initial short time, and subsequent entrapment of air bubbles can be suppressed. In addition, the heat generation of the piezoelectric element 132 can be suppressed.

[0090] <Fifth Embodiment> Next, a fifth embodiment will be described using Figure 10. Figure 10 is an explanatory diagram showing the relationship between the drive signal and the needle displacement in the fifth embodiment.

[0091] In the fifth embodiment, the drive signal is a stepped waveform defined by a closed voltage E1 and two open voltages Em and E2, as shown in Figure 10(a). The definitions of the closed voltage and open voltage are the same as in the embodiments described above.

[0092] The open-circuit voltage Em is set to a different value from the open-circuit voltage E2 (a value smaller than the open-circuit voltage E2 in this embodiment). First, the open-circuit voltage Em is applied to the piezoelectric element 132 for a period of time t1, and then the open-circuit voltage E2 is applied to the piezoelectric element 132 for a period of time t2. In the fifth embodiment, the open-circuit voltage Em is an example of a "first voltage," and the open-circuit voltage E2 is an example of a "second voltage." Also, the period of time t1 during which the open-circuit voltage Em is applied is an example of a "first period," and the period of time t2 during which the open-circuit voltage E2 is applied is an example of a "second period."

[0093] Also in the fifth embodiment, similarly to the fourth embodiment, the needle 131 is not displaced all at once from the position P1 to the position P2, but a period for maintaining the position Pm as shown in Fig. 10(b) is provided on the way. Thereby, rapid pressure fluctuation in the liquid chamber 114 can be suppressed. In addition, since the vibration of the needle 131 becomes gentle, entrainment of air bubbles into the liquid chamber 114 can be reduced, and heat generation of the piezoelectric element 132 can be reduced.

[0094] When discharging liquid droplets at a high-speed cycle, the time spent until discharging can be set to one peak of the amplitude of the needle 131. In this case, as shown in Fig. 10(b), entrainment of air bubbles can be reduced by suppressing the steepness (the slope of the curve) until reaching the position P2 from the position P1.

[0095] As an example of the fifth embodiment, when the natural vibration period of the needle 131 is T, the time t1 is defined so as to satisfy the relationship of t1<1 / 2T, and the time t2 is defined so as to satisfy the relationship of t2<1 / 2T. Thereby, the needle 131 can be temporarily stagnated near the position Pm in the middle of being displaced toward the position P2 to suppress entrainment of air bubbles, and at the timing when "air bubble discharge" ends, the liquid can be discharged in a state where the air bubbles have been discharged. In addition, the open-circuit voltage Em is defined so as to satisfy the relationship of 2 / 3E2<Em<E2 with respect to the open-circuit voltage E2. It is desirable that the voltage slew rate makes the rise time of the waveform 1 / 8T or less. For example, if the waveform of the drive signal is the drive waveform as shown in Fig. 10, two rises occur in the process of elapsing the time of 1 / 2T, so that 1 / 4T divided into two is allocated to each individual rise. Further, considering that the respective times are not equal, it is desirable to set it to 1 / 8T.

[0096] As described above, in the present embodiment, the needle 131 vibrates at the natural vibration period T in the moving direction of the needle 131 at the position where the nozzle hole 102 is opened, and the time t1 is shorter than half of the natural vibration period T.

[0097] Furthermore, as mentioned above, time t2 is shorter than half of the natural oscillation period T.

[0098] This suppresses the entrapment of air bubbles and allows the liquid to be dispensed while the air bubbles are expelled.

[0099] Furthermore, the drive signals shown in the first to fifth embodiments may not be perfect square waves, but rather waveforms having a predetermined slope for the connecting portion (slew rate). In other words, the voltages between the closing voltage, the first voltage, and the second voltage may be switched by a predetermined slew rate. In that case, the slew rate is preferably sufficiently short compared to the natural oscillation period T of the needle 131, for example, preferably 1 / 8T or less.

[0100] [Another example of a head unit configuration] Another example of the head unit configuration will be described with reference to Figure 11. Figure 11 is a cross-sectional view showing another example of the head unit configuration according to the embodiment, where Figure 11(a) is a cross-sectional view showing the nozzle holes in a closed state, and Figure 11(b) is a cross-sectional view showing the nozzle holes in an open state.

[0101] This configuration example differs from the head unit configuration shown in Figure 1 and other figures in that it includes a reverse spring mechanism 134 as an example of a transmission mechanism between the needle 131 and the piezoelectric element 132. Therefore, this explanation will focus on the configuration and operation of the reverse spring mechanism 134, and components having the same configuration and function as those in the head unit of Figure 1 will be given the same reference numerals and their descriptions will be omitted. In this configuration example, the piezoelectric element 132 used has the characteristic of expanding and contracting toward the nozzle plate 101 when a voltage is applied.

[0102] The reverse spring mechanism 134 is an elastic member formed by molding rubber, soft resin, or a thin metal plate that can be appropriately deformed. The reverse spring mechanism 134 comprises a deformable portion 134a, a fixed portion 134b, a guide portion 134c, and a bent edge 134d.

[0103] The deformed portion 134a has a substantially trapezoidal cross-section and is formed so as to abut against the base end surface of the needle 131 (the upper end surface of the needle 131 in Figure 11(a)).

[0104] The fixing portion 134b is fixed to the deformable portion 134a and to the inner wall surface of the housing 110.

[0105] The guide section 134c connects the fixing section 134b and the piezoelectric element 132.

[0106] The bent side 134d connects the longer side (corresponding to the bottom base of the trapezoid) of the trapezoidal deformation part 134a to the fixing part 134b.

[0107] In the reverse spring mechanism 134 configured as described above, when a predetermined voltage is applied to the piezoelectric element 132 and the piezoelectric element 132 extends, the extension of the piezoelectric element 132 pushes the guide portion 134c toward the nozzle hole 102 (in the direction of arrow a in Figure 11(b)).

[0108] This pushing force pulls the deformable portion 134a away from the nozzle hole 102 (in the direction of arrow b in Figure 11(b)). In other words, the reverse spring mechanism 134 converts the stretching force of the piezoelectric element 132 into a force that pulls in the needle 131, and then transmits it to the needle 131.

[0109] In this configuration example, when a voltage is applied to the piezoelectric element 132 of the head 100, the piezoelectric element 132 extends, and consequently the valve member 130 opens the nozzle hole 102, discharging a droplet 10' from the nozzle hole 102.

[0110] As described above, this configuration example includes a reverse spring mechanism 134 between the needle 131 and the piezoelectric element 132 that converts the stretching force of the piezoelectric element 132 into a force that pulls the needle 131 in, that is, a force opposite to the stretching force of the piezoelectric element 132, and then transmits it to the needle 131.

[0111] In the head unit HU of this configuration example, by using the drive signals described in the first to fifth embodiments, it is possible to reduce liquid discharge failures caused by air bubbles being trapped in the nozzle hole 102. However, in the case of the head unit shown in Figure 4, the nozzle hole 102 closes when the piezoelectric element 132 extends and opens when the piezoelectric element 132 contracts, but in the case of a head unit equipped with a reverse spring mechanism 134, this relationship is reversed.

[0112] In other words, in the case of a head unit equipped with a reverse spring mechanism 134, when the piezoelectric element 132 extends, the nozzle hole 102 opens as shown in Figure 11(b), and when the piezoelectric element 132 contracts, the nozzle hole 102 closes as shown in Figure 11(a). Therefore, in a head unit equipped with a reverse spring mechanism 134, the drive signals shown in the first to fifth embodiments should be used, taking into account that the relationship between the extension and contraction of the piezoelectric element 132 and the opening and closing of the nozzle hole 102 is reversed.

[0113] The head 100 equipped with the reverse spring mechanism 134 can obtain a large displacement with less displacement of the piezoelectric element 132 compared to a head without the reverse spring mechanism. Furthermore, by providing the reverse spring mechanism 134 between the needle 131 and the piezoelectric element 132, the natural vibration period can be lengthened, thereby suppressing the natural vibration speed of the needle 131 during the first or second period, and reducing the entrapment of air bubbles.

[0114] Furthermore, the present invention can be applied not only to heads equipped with a reverse spring mechanism, but also to heads with low rigidity, heads that easily pick up vibrations originating from liquid dispensing devices, and the like.

[0115] Furthermore, the above description assumes a piezoelectric element having expansion and contraction characteristics, which extend when voltage E1 is applied and contract when a voltage greater than E1 is applied. However, the present invention is not limited to this. For example, a piezoelectric element having expansion and contraction characteristics, which contract when voltage E1 is applied and extend when a voltage greater than E1 is applied, may be used.

[0116] [Method for measuring natural vibration period] Figure 12 is an explanatory diagram illustrating an example of a method for measuring the natural vibration period.

[0117] The natural vibration period T of the needle 131 is determined by measuring the surface of the needle 131 that contacts the nozzle plate 101' (in this embodiment, the end face of the valve member 130 joined to the needle 131).

[0118] A laser Doppler displacement sensor 901 is used for measurement. The laser beam 902 emitted from the laser Doppler displacement sensor 901 is irradiated onto the end face of the valve member 130, which is the object of measurement. The natural vibration period T can be determined by performing a Fourier analysis on the obtained measurement values.

[0119] Measurements should preferably be performed under the same driving conditions as the actual liquid ejection operation. This involves continuously applying the actual drive waveform to the print head, and, in the case of a print head where ink is supplied to the liquid chamber under pressure, it is desirable to perform the measurements while supplying the ink under pressure.

[0120] When the laser beam 902 is directed towards the nozzle hole 102', it may be obstructed by the ink droplets 10A' ejected from the nozzle hole 102' during measurement, making it impossible to correctly measure the object to be measured. Therefore, the laser beam 902 is directed away from the position of the nozzle hole 102'. However, the nozzle plate 101 actually used is not made of a material that allows the laser beam 902 to pass through. Therefore, when the laser beam 902 is directed away from the position of the nozzle hole 102' as described above, the problem arises that the laser beam 902 may not reach the object to be measured.

[0121] Therefore, in this embodiment, during measurement, the nozzle plate 101' is replaced with one made of a material that allows the laser beam 902 to pass through, so that the laser beam 902 can reach the object to be measured. The nozzle plate 101' can be made of any material that allows the laser beam 902 to pass through, and the material is not particularly limited, but glass is preferred from the viewpoint of laser beam 902 transmittance and component rigidity.

[0122] The ink 10A used for measurement is a transparent ink because, if it were the actual ink 10, for example, the filler components contained in the ink 10 would obstruct the transmission of the laser light 902. However, it is desirable to use an ink 10A that has kinematic viscosity characteristics equivalent to the actual ink 10 for measurement.

[0123] A deflection device 903 may be installed between the laser Doppler displacement meter 901 and the head 100 to change the direction of the ink droplet 10A'. The deflection device 903 consists of, for example, a blower fan, which blows air onto the ink droplet 10A' in a direction that moves the ink droplet 10A' away from the optical path of the laser beam 902. This prevents interference with measurements by the ink droplet 10A' and contamination of the laser Doppler displacement meter 901.

[0124] [Coating device] Next, we will describe a coating apparatus to which the above-mentioned head unit is applied.

[0125] <Examples of application to vehicle body painting systems> As an example of a coating apparatus, an application example to a vehicle body painting system will be explained using Figures 13 and 14. Figure 13 is an explanatory diagram showing an example of a coating apparatus. Figure 14 is an explanatory diagram showing an example of the use of the coating apparatus, where Figure 14(a) shows a first example of the placement of the coating apparatus on the object, and Figure 14(b) shows a second example of the placement of the coating apparatus on the object.

[0126] The coating apparatus 1001 includes at least one head 100, a camera 1004 disposed near the head 100, an XY table 1003 for moving the head 100 and camera 1004 in the X and Y directions, image editing software S for editing images captured by the camera 1004, a monitor 1010 for displaying the images to be edited, and a control unit 600, etc. The control unit 600 operates the XY table 1003 and discharges liquid from the head 100 based on a predetermined control program.

[0127] The coating device 1001 can apply the liquid (e.g., ink 10) dispensed by the head 100 to the object U.

[0128] The print head 100 ejects ink 10 from the nozzle hole 102 toward the surface of the object U to be coated. The ink 10 ejected from the nozzle hole 102 is ejected in a direction approximately perpendicular to the XY plane. The distance between the nozzle hole 102 and the surface of the object U to be coated is, for example, about 20 cm.

[0129] The XY table 1003 has an X-axis 1005 formed with a linear movement mechanism, and a Y-axis 1006 that moves the X-axis 1005 in the Y direction while holding the X-axis 1005 with two arms. The X-axis 1005 corresponds to the rail member 303 in Figure 2, and the head 100 and camera 1004 are attached to the head holding member 301 in Figure 2. A shaft 1007 is provided on the Y-axis 1006. By holding this shaft 1007 with the robot arm 1008, the head 100 and camera 1004 can be freely positioned relative to the object U.

[0130] For example, if the object U is a car, the robot arm 1008 can be positioned on top of the object U as shown in Figure 14(a), or to the side of the object U as shown in Figure 14(b). The control unit 600 controls the movement of the robot arm 1008 based on a predetermined program.

[0131] The camera 1004 moves with the head 100 in the XY direction and captures images of a predetermined area on the surface of the object U to be coated at constant minute intervals. The camera 1004 is, for example, a digital camera. In the camera 1004, specifications such as lens specifications or resolution are appropriately selected to enable the capture of multiple subdivided images that divide a predetermined area of ​​the surface to be coated. The capture of multiple subdivided images of the surface to be coated by the camera 1004 is performed continuously and automatically according to a program pre-programmed in the control unit 600.

[0132] As described above, the coating device 1001, having a head 100, can apply the ink 10 to a desired position on the object U with high precision, even when the distance between the object U and the nozzle hole 102 is long. Furthermore, since the head 100 can stably eject the ink 10, the coating device 1001 can apply the ink 10 to the object U with high precision.

[0133] <Examples of application to electrode manufacturing equipment> Next, as another example of a coating apparatus, we will explain its application to an electrode manufacturing apparatus using Figure 15. Figure 15 is an explanatory diagram showing an example of an electrode manufacturing apparatus.

[0134] The electrode manufacturing apparatus 800 is an apparatus for manufacturing electrodes having a layer containing electrode material by discharging a liquid composition using the head 100 described above.

[0135] By discharging the liquid composition from the head 100, the liquid composition can be applied to the target object to form a liquid composition layer. In this case, there are no particular restrictions on the target object as long as it is an object on which a layer containing electrode material can be formed, and it can be appropriately selected according to the purpose. Examples include electrode substrates (current collectors), active material layers, and layers containing solid electrode material. Furthermore, the application of the liquid composition to the target object may be done by directly discharging the liquid composition to form a layer containing electrode material on the target object, or by indirectly discharging the liquid composition to form a layer containing electrode material, as long as it is possible to form a layer containing electrode material on the target object.

[0136] Other components in the electrode manufacturing apparatus can be appropriately selected depending on the purpose, and examples include heating means. The heating means is a means for heating the liquid composition discharged by the head 100. Heating can dry the liquid composition layer.

[0137] Figure 15 shows an example of an electrode manufacturing apparatus, illustrating a configuration in which an electrode composite layer containing active material is formed on an electrode substrate (current collector).

[0138] The electrode manufacturing apparatus 800 includes an extrusion process section 801 which includes a step of applying a liquid composition onto a printing substrate W having an object to be manufactured to form a liquid composition layer, and a heating process section 802 which includes a heating step of heating the liquid composition layer to obtain an electrode composite layer.

[0139] The electrode manufacturing apparatus 800 includes transport units 803 and 804 for transporting the printing substrate W. The transport units 803 and 804 transport the printing substrate W at a preset speed in the order of the ejection process unit 801 and the heating process unit 802. There are no particular restrictions on the method for manufacturing the printing substrate W having an active material layer or the like, and known methods can be appropriately selected.

[0140] The discharge process unit 801 includes a printing apparatus 811 that performs a dispensing process for applying a liquid composition onto a printing substrate W, a storage container 812 for containing the liquid composition, and a supply tube 813 for supplying the liquid composition stored in the storage container 812 to the printing apparatus 811. The printing apparatus 811 is equipped with at least one of the heads 100 described above.

[0141] The containment container 812 contains the liquid composition 10B, and the dispensing process unit 801 dispenses the liquid composition 7 from the head 100 provided in the printing device 811 to apply the liquid composition 10B onto the printing substrate W, forming a thin film layer of the liquid composition. The containment container 812 may be integrated with the electrode manufacturing device 800, or it may be detachable from the electrode manufacturing device 800. Alternatively, it may be a container used for adding to the containment container 812, whether integrated with the electrode manufacturing device 800 or detachable from the electrode manufacturing device 800.

[0142] The containment container 812 and the supply tube 813 can be arbitrarily selected as long as they are capable of stably storing and supplying the liquid composition 10B.

[0143] The heating process section 802 includes a heating device 821 and includes a solvent removal step in which the solvent remaining in the liquid composition layer is heated and dried by the heating device 821 to remove it. This allows for the formation of an electrode composite layer. The heating process section 802 may perform the solvent removal step under reduced pressure.

[0144] There are no particular restrictions on the heating device 821, and it can be appropriately selected according to the purpose. Examples include substrate heating, IR heaters, and hot air heaters, and these may be combined. Furthermore, the heating temperature and time can be appropriately selected according to the boiling point of the solvent contained in the liquid composition 10B and the film thickness to be formed.

[0145] The electrode composite layer formed as described above can be suitably used, for example, as part of the configuration of an electrochemical element. There are no particular restrictions on components other than the electrode composite layer in the electrochemical element, and known components can be appropriately selected, such as a positive electrode, a negative electrode, and a separator.

[0146] The head unit according to this embodiment is not limited to a vehicle body painting system or an electrode manufacturing apparatus, but may also be an image forming apparatus that forms an image on a recording medium such as paper.

[0147] [Application Examples] Next, we will explain application examples with reference to Figure 16. Figure 16 is an explanatory diagram showing application examples.

[0148] As shown in Figure 16, the head module 700 is equipped with multiple (eight in the example of Figure 16) heads 100 in a housing 710. The housing 710 has a supply port 711 for supplying ink 10 into the housing 710, a supply passage 712 connecting the supply port 711 and the injection port 713, and an outlet port 715 provided on the opposite side of the injection port 713, across the liquid chamber 714. The housing 710 also has a recovery port 717 for recovering the ink 10 inside the housing 710, and a recovery passage 716 connecting the recovery port 717 and the outlet port 715.

[0149] The basic configuration of the multiple heads 100 is the same as that described in Figures 1 and 4, and in Figure 16, the corresponding elements are given symbols in the 700 series. Alternatively, the multiple heads 100 may be composed of heads equipped with the reverse spring mechanism shown in Figure 11.

[0150] In this application example, eight heads 100 are provided such that their respective nozzle holes 702 are arranged at approximately equal intervals in one direction (left-right direction in Figure 16). Each of the heads 100 extends vertically so as to eject ink 10 downwards from the nozzle hole 702 at the bottom of the figure.

[0151] The liquid chamber 714 of each of the eight heads 100 is provided to penetrate the arrangement of the eight heads 100, allowing the ink 10 to flow from one side (left side in Figure 16) to the other side (right side in Figure 16). In other words, the configuration differs from the above-described embodiment in that each head 100 has an outlet 715 on the opposite side of the injection port 713.

[0152] In the above configuration, by applying the drive signals described in the first to fifth embodiments to the piezoelectric elements 732 of each head 100, it is possible to reduce liquid discharge failures caused by air bubbles being trapped in each nozzle hole 702.

[0153] In this invention, the liquid may be a solution, suspension, emulsion, or the like containing a solvent such as water or an organic solvent, a coloring agent such as a dye or pigment, a polymerizable compound, a resin, a functionalizing material such as a surfactant, a biocompatible material such as DNA, amino acids or proteins, calcium, or an edible material such as a natural pigment.

[0154] These can be used, for example, in inkjet inks, coatings, surface treatment liquids, components for electronic elements and light-emitting elements, liquids for forming electronic circuit resist patterns, and 3D fabrication materials.

[0155] The above is merely an example, and the present invention provides specific effects in each of the following embodiments.

[0156] [First aspect] The first embodiment is a liquid discharge head (e.g., head 100) having a liquid chamber (e.g., liquid chamber 114) for containing a pressurized liquid (e.g., ink 10), a nozzle hole (e.g., nozzle hole 102) for discharging the liquid, a valve body (e.g., needle 131) provided in the liquid chamber, and a drive body (e.g., piezoelectric element 132) for moving the valve body to a position where the valve body closes the nozzle hole and a position where the valve body opens the nozzle hole, and an opening for the drive body to move the valve body to a position where the nozzle hole is open. A head unit (e.g., head unit HU) comprising a drive control unit (e.g., drive control unit 500) that applies a voltage and a closing voltage to move the valve body to a position that closes the nozzle hole, wherein the signal waveform of the open-circuit voltage has a first period (e.g., time t1 in Figure 6) in which a first voltage (e.g., open-circuit voltage E3 in Figure 6) is applied, and a second period (e.g., time t2 in Figure 6) after the first period in which a second voltage different from the first voltage (e.g., open-circuit voltage E2 in Figure 6) is applied.

[0157] [Second aspect] The second embodiment is characterized in that, in the first embodiment, the second voltage (for example, the open-circuit voltage E2 in Figure 6) is a voltage between the closed-circuit voltage (for example, the closed-circuit voltage E1 in Figure 6) and the first voltage (for example, the open-circuit voltage E3 in Figure 6).

[0158] [Third aspect] The third embodiment is characterized in that, in the second embodiment, the valve body (e.g., needle 131) vibrates at a natural vibration period (e.g., natural vibration period T in Figure 6) in the direction of movement of the valve body when the nozzle hole (e.g., nozzle hole 102) is open, and the second period (e.g., time t2 in Figure 6) is shorter than half of the natural vibration period.

[0159] [Fourth aspect] The fourth aspect is characterized in that, in the second aspect, the valve body (e.g., needle 131) vibrates at a natural vibration period (e.g., natural vibration period T in Figure 6) in the direction of movement of the valve body when the nozzle hole (e.g., nozzle hole 102) is open, and the first period (e.g., time t1 in Figure 6) is longer than the natural vibration period and shorter than 3 / 2 of the natural vibration period.

[0160] [Fifth aspect] The fifth embodiment is characterized in that, in the first embodiment, the first voltage (for example, the open-circuit voltage E2 in Figures 7 and 8, and the open-circuit voltage Em in Figures 9 and 10) is a voltage between the closed-circuit voltage (for example, the closed-circuit voltage E1 in Figures 7, 8, 9, and 10) and the second voltage (for example, the open-circuit voltage E3 in Figures 7 and 8, and the open-circuit voltage E2 in Figures 9 and 10).

[0161] [Sixth aspect] The sixth embodiment is characterized in that, in the first or fifth embodiment, the valve body (e.g., needle 131) vibrates at a natural vibration period (e.g., natural vibration period T in Figures 7 and 8) in the direction of movement of the valve body when the nozzle hole (e.g., nozzle hole 102) is open, and the first period (e.g., time t1 in Figures 7 and 8) is longer than half of the natural vibration period and shorter than the natural vibration period.

[0162] [Seventh aspect] The seventh embodiment is characterized in that, in the first, fifth, or sixth embodiment, the valve body (e.g., needle 131) vibrates at a natural vibration period in the direction of movement of the valve body (e.g., natural vibration period T in Figures 9 and 10) when the nozzle hole (e.g., nozzle hole 102) is open, and the first period (e.g., time t1 in Figures 9 and 10) is shorter than half of the natural vibration period.

[0163] [8th aspect] The eighth aspect is characterized in that, in the seventh aspect, the second period (for example, time t2 in Figure 10) is shorter than half of the natural vibration period (for example, the natural vibration period T in Figure 10).

[0164] [Ninth aspect] The ninth aspect is characterized in that, in any of the first to eighth aspects, the liquid discharge head (e.g., head 100) comprises a nozzle plate (e.g., nozzle plate 101) having the nozzle hole (e.g., nozzle hole 102) formed thereon, and the valve body (e.g., needle 131) closes the nozzle hole by contacting the nozzle plate and opens the nozzle by moving away from the nozzle plate.

[0165] [Tenth aspect] The tenth embodiment is characterized in that, in any of the first to ninth embodiments, a transmission mechanism (e.g., a reverse spring mechanism 134) is provided between the valve body (e.g., a needle 131) and the drive body (e.g., a piezoelectric element 132) that converts the extension force of the drive body into a force that pulls in the valve body and transmits it to the valve body.

[0166] [Phase 11] The eleventh embodiment is a liquid dispensing device characterized by comprising a head unit (e.g., head unit HU) according to any of the first to tenth embodiments, and a pressurizing means (e.g., pressurizing mechanism 200) for supplying pressurized liquid to a liquid dispensing head (e.g., head 100) provided on the head unit.

[0167] [12th aspect] The twelfth embodiment is characterized in that, in the eleventh embodiment, it is equipped with a moving means (e.g., a head moving mechanism 300) for moving the liquid discharge head (e.g., head 100) relative to the object.

[0168] [The 13th aspect] The 13th embodiment is a coating apparatus that comprises a liquid dispensing device according to the 11th or 12th embodiment, and is characterized by applying the liquid to an object (for example, object U in Figure 14, printing substrate W in Figure 15).

[0169] [Aspect 14] The 14th embodiment is a drive device (e.g., drive control unit 500) for driving a liquid discharge head (e.g., head 100) having a liquid chamber (e.g., liquid chamber 114) for containing a pressurized liquid (e.g., ink 10), a nozzle hole (e.g., nozzle hole 102) for discharging the liquid, a valve body (e.g., needle 131) provided in the liquid chamber, and a drive body (e.g., piezoelectric element 132) for moving the valve body to a position where the valve body closes the nozzle hole and a position where the valve body opens the nozzle hole, wherein the drive device moves the drive body to a position where the nozzle hole opens An open-circuit voltage is applied to move the valve body to a position, controlling the discharge of the liquid from the nozzle hole; a closing voltage is applied to the drive body to move the valve body to a position that closes the nozzle hole, controlling the discharge of the liquid from the nozzle hole; the signal waveform of the open-circuit voltage is characterized by having a first period (for example, time t1 in Figure 6) in which a first voltage (for example, open-circuit voltage E3 in Figure 6) is applied, and a second period (for example, time t2 in Figure 6) after the first period in which a second voltage different from the first voltage (for example, open-circuit voltage E2 in Figure 6) is applied.

[0170] [Aspect 15] The 15th aspect is a driving method for driving a liquid discharge head (e.g., head 100) having a liquid chamber (e.g., liquid chamber 114) for containing a pressurized liquid (e.g., ink 10), a nozzle hole (e.g., nozzle hole 102) for discharging the liquid, a valve body (e.g., needle 131) provided in the liquid chamber, and a drive body (e.g., piezoelectric element 132) for moving the valve body to a position where the valve body closes the nozzle hole and a position where the valve body opens the nozzle hole, wherein the drive body moves to a position where the nozzle hole opens The invention is characterized by comprising: a first step of applying a first voltage (for example, the open-circuit voltage E3 in Figure 6) to move the valve body; a second step, after the first step, of applying a second voltage (for example, the open-circuit voltage E2 in Figure 6) to the drive body, which is a voltage that moves the valve body to a position that opens the nozzle hole and is different from the first voltage; and a third step, after the second step, of applying a closing voltage (for example, the closing voltage E1 in Figure 6) to the drive body to move the valve body to a position that closes the nozzle hole. [Explanation of symbols]

[0171] 10 Ink 100 heads 101 Nozzle Plate 102 Nozzle holes 113 Inlet 114 Liquid chamber 130 Valve member 131 Needle (an example of a valve body) 132 Piezoelectric element (an example of a driving element) 134 Reverse spring mechanism (an example of a transmission mechanism) 500 Drive Control Unit (Example of a drive device) 200 Pressurization mechanism (an example of pressurization means) 300 Head movement mechanism (an example of a means of movement) 600 Control Unit HU Head Unit

Claims

1. A liquid discharge head having a liquid chamber for containing pressurized liquid, a nozzle hole for discharging the liquid, a valve body provided in the liquid chamber, and a drive body for moving the valve body to a position where the valve body closes the nozzle hole and a position where the valve body opens the nozzle hole, A head unit comprising the drive body and a drive control unit that applies an opening voltage to move the valve body to a position that opens the nozzle hole and a closing voltage to move the valve body to a position that closes the nozzle hole, The signal waveform of the open-circuit voltage has a first period during which a first voltage is applied, and a second period after the first period during which a second voltage different from the first voltage is applied. The second voltage is the voltage between the closing voltage and the first voltage, The valve body vibrates at a natural vibration period in the direction of movement of the valve body when the nozzle hole is open. The head unit is characterized in that the second period is shorter than half of the natural vibration period.

2. A liquid discharge head having a liquid chamber for containing a pressurized liquid, a nozzle hole for discharging the liquid, a valve body provided in the liquid chamber, and a drive body for moving the valve body to a position in which the valve body closes the nozzle hole and a position in which the valve body opens the nozzle hole, A head unit comprising the drive body and a drive control unit that applies an opening voltage to move the valve body to a position that opens the nozzle hole and a closing voltage to move the valve body to a position that closes the nozzle hole, The signal waveform of the open-circuit voltage has a first period during which a first voltage is applied, and a second period after the first period during which a second voltage different from the first voltage is applied. The second voltage is the voltage between the closing voltage and the first voltage, The valve body vibrates at a natural vibration period in the direction of movement of the valve body when the nozzle hole is open. The head unit is characterized in that the first period is longer than the natural vibration period and shorter than 3 / 2 of the natural vibration period.

3. A liquid discharge head having a liquid chamber for containing a pressurized liquid, a nozzle hole for discharging the liquid, a valve body provided in the liquid chamber, and a drive body for moving the valve body to a position where the valve body closes the nozzle hole and a position where the valve body opens the nozzle hole, A head unit comprising the drive body and a drive control unit that applies an opening voltage to move the valve body to a position that opens the nozzle hole and a closing voltage to move the valve body to a position that closes the nozzle hole, The signal waveform of the open-circuit voltage has a first period during which a first voltage is applied, and a second period after the first period during which a second voltage different from the first voltage is applied. The head unit according to claim 1, characterized in that the first voltage is a voltage between the closing voltage and the second voltage.

4. The valve body vibrates at a natural vibration period in the direction of movement of the valve body when the nozzle hole is open. The head unit according to claim 3, characterized in that the first period is longer than half of the natural vibration period and shorter than the natural vibration period.

5. The valve body vibrates at a natural vibration period in the direction of movement of the valve body when the nozzle hole is open. The head unit according to claim 3, characterized in that the first period is shorter than half of the natural vibration period.

6. The head unit according to claim 5, characterized in that the second period is shorter than half of the natural vibration period.

7. The liquid discharge head comprises a nozzle plate in which the nozzle holes are formed, The head unit according to claim 1, characterized in that the valve body closes the nozzle hole by contacting the nozzle plate and opens the nozzle hole by moving away from the nozzle plate.

8. The head unit according to claim 1, further comprising a transmission mechanism between the valve body and the drive body that converts the extension force of the drive body into a force that pulls the valve body in and transmits it to the valve body.

9. A head unit according to any one of claims 1 to 8, A liquid dispensing device characterized by comprising a pressurizing means for supplying pressurized liquid to a liquid dispensing head provided in the head unit.

10. The liquid dispensing device according to claim 9, further comprising a means for moving the liquid dispensing head relative to an object.

11. A coating apparatus comprising a liquid dispensing device as described in claim 9, characterized in that it applies the liquid to an object.

12. A drive device for driving a liquid discharge head having a liquid chamber for containing pressurized liquid, a nozzle hole for discharging the liquid, a valve body provided in the liquid chamber, and a drive body for moving the valve body to a position where the valve body closes the nozzle hole and a position where the valve body opens the nozzle hole, An open-circuit voltage is applied to the drive unit to move the valve body to a position that opens the nozzle hole, and the liquid is controlled to be discharged from the nozzle hole. A closing voltage is applied to the drive unit to move the valve body to a position that closes the nozzle hole, thereby controlling the system so that the liquid is not discharged from the nozzle hole. The signal waveform of the open-circuit voltage has a first period during which a first voltage is applied, and a second period after the first period during which a second voltage different from the first voltage is applied. The second voltage is the voltage between the closing voltage and the first voltage, The valve body vibrates at a natural vibration period in the direction of movement of the valve body when the nozzle hole is open. The drive device is characterized in that the second period is shorter than half of the natural vibration period.

13. A driving method for driving a liquid discharge head having a liquid chamber for containing a pressurized liquid, a nozzle hole for discharging the liquid, a valve body provided in the liquid chamber, and a drive body for moving the valve body to a position where the valve body closes the nozzle hole and a position where the valve body opens the nozzle hole, The first step is to apply a first voltage to the drive unit to move the valve body to a position that opens the nozzle hole, A second step is to apply a second voltage to the drive body, which is different from the first voltage, and is a voltage that moves the valve body to a position that opens the nozzle hole. The third step, performed after the second step, involves applying a closing voltage to the drive unit to move the valve body to a position that closes the nozzle hole. The second voltage is the voltage between the closing voltage and the first voltage, The valve body vibrates at a natural vibration period in the direction of movement of the valve body when the nozzle hole is open. A driving method characterized in that the period during which the second voltage is applied in the second step is shorter than half of the natural oscillation period.

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