JPWO2019064770A1 - Liquid agent application device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid agent coating device capable of suppressing damage to a piezoelectric element. A liquid agent coating device (10) includes a diaphragm (12) for changing the internal volume of a liquid agent storage unit (11), a piezoelectric element (13) located on the diaphragm (12), and a preload spring (14) located on the piezoelectric element (13). ..

Description

The present invention relates to a liquid agent coating device.

Piezoelectric elements that convert energy from electrical energy to mechanical energy by the piezoelectric effect have excellent responsiveness. Therefore, in a wide range of fields such as semiconductors, printing, and chemicals, a liquid agent coating device that discharges a liquid agent onto the surface of an object. It is used for.

The liquid agent coating device generally includes a liquid agent storage unit having a discharge port, a diaphragm that changes the volume in the liquid agent storage unit, and a piezoelectric element that pressurizes and vibrates the diaphragm (see, for example, Patent Document 1).

JP-A-2007-160701

However, when the stretched piezoelectric element contracts, the contraction speed of the piezoelectric element is faster than the return speed of the diaphragm, so that the piezoelectric element may be damaged.

Specifically, when the piezoelectric element is connected to the diaphragm (that is, when the piezoelectric element is fixed to the diaphragm), a tensile force is applied from the diaphragm to the piezoelectric element, causing the piezoelectric element to peel off from the diaphragm. Alternatively, the inside of the piezoelectric element may be damaged.

Further, when the piezoelectric element is in contact with the diaphragm (that is, when the piezoelectric element is not fixed to the diaphragm), the weight of the piezoelectric element causes a tensile force inside the piezoelectric element, causing damage to the inside of the piezoelectric element. May occur.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a liquid agent coating device capable of suppressing damage to a piezoelectric element.

The liquid agent coating device according to one aspect of the present invention includes a liquid agent storage unit, a diaphragm, a drive unit, and a preload mechanism. The liquid agent storage unit has a liquid agent discharge port. The diaphragm changes the internal volume of the liquid agent reservoir. The drive unit is located above the diaphragm. The preload mechanism is located above the drive unit.

According to one aspect of the present invention, it is possible to provide a liquid agent coating device capable of suppressing damage to the piezoelectric element.

It is a schematic diagram which shows the structure of the liquid agent coating apparatus which concerns on embodiment. It is a schematic diagram which shows the other structure of the liquid agent coating apparatus which concerns on embodiment. It is a schematic diagram for demonstrating the operation when the piezoelectric element which concerns on embodiment is in contact with a diaphragm. It is a schematic diagram for demonstrating the operation when the piezoelectric element which concerns on embodiment is connected to a diaphragm.

Hereinafter, the liquid agent coating device according to the embodiment of the present invention will be described with reference to the drawings. However, the scope of the present invention is not limited to the following embodiments, and can be arbitrarily changed within the scope of the technical idea of the present invention. Further, in the following drawings, the scale and the number of each structure may be different from the scale and the number of the actual structure in order to make each configuration easy to understand.

As used herein, "connection" means a state in which two members are fixed or connected to each other. Therefore, when two members are connected, they always operate together. Further, "contact" means a state in which the two members are in direct contact with each other, but the two members are not fixed or connected to each other. When two members are in contact, they may work together or they may not work together.

FIG. 1 is a schematic view showing the configuration of the liquid agent coating device 10 according to the first embodiment.

The liquid agent coating device 10 includes a liquid agent storage unit 11, a diaphragm 12, a piezoelectric element 13, a preload spring 14 (an example of a preload mechanism), a fixing member 15, and a control unit 16. The liquid agent storage portion 11, the diaphragm 12, the piezoelectric element 13, and the fixing member 15 constitute the head 17.

(1) Liquid agent storage unit 11 The liquid agent storage unit 11 has a housing 11a and a nozzle 11b.

The housing 11a is formed in a hollow shape. In the present embodiment, the housing 11a is formed in a tubular shape, but the housing 11a is not limited to this. The housing 11a can be made of, for example, an alloy material, a ceramic material, a synthetic resin material, or the like.

A pressure chamber 11c is formed inside the housing 11a. The liquid agent is stored in the pressure chamber 11c. Examples of the liquid agent include, but are not limited to, solder, thermosetting resin, ink, and a coating liquid for forming a functional thin film (alignment film, resist, color filter, organic electroluminescence, etc.).

A liquid agent supply port 11d is formed on the side wall of the housing 11a. The liquid agent supplied from the liquid agent supply device 30 via the liquid agent supply pipe 31 passes through the liquid agent supply port 11d and is replenished in the pressure chamber 11c.

The nozzle 11b is formed in a plate shape. The nozzle 11b is arranged so as to close one end opening of the housing 11a. A discharge port 11e is formed in the nozzle 11b. The liquid agent in the pressure chamber 11c is discharged to the outside as droplets from the discharge port 11e.

(2) Diaphragm 12 The diaphragm 12 is arranged so as to close the other end opening of the housing 11a. The diaphragm 12 elastically vibrates when pressure vibration is applied from the piezoelectric element 13 described later. As a result, the diaphragm 12 changes the volume of the pressure chamber 11c formed in the liquid agent storage portion 11.

When the diaphragm 12 curves convexly toward the inside of the pressure chamber 11c, the volume of the pressure chamber 11c becomes smaller. As a result, the liquid agent is discharged from the discharge port 11e. After that, when the diaphragm 12 returns to the steady state due to its own elasticity, the volume of the pressure chamber 11c also returns to the original state. At this time, the liquid agent is replenished from the liquid agent supply port 11d to the pressure chamber 11c.

The constituent material of the diaphragm 12 is not particularly limited, but for example, an alloy material, a ceramic material, a synthetic resin material, or the like can be used.

(3) Piezoelectric element 13 The piezoelectric element 13 is an example of a “driving unit” that vibrates and drives the diaphragm 12. The piezoelectric element 13 is located above the diaphragm 12. The piezoelectric element 13 is arranged between the diaphragm 12 and the preload spring 14. The piezoelectric element 13 is sandwiched between the diaphragm 12 and the preload spring 14.

The first end portion 13p of the piezoelectric element 13 comes into contact with the diaphragm 12. The first end portion 13p of the piezoelectric element 13 may only be in contact with the diaphragm 12 or may be connected to the diaphragm 12. That is, the first end portion 13p of the piezoelectric element 13 may or may not be fixed to the diaphragm 12. When connecting the first end portion 13p of the piezoelectric element 13 to the diaphragm 12, an adhesive such as an epoxy resin can be used. The first end portion 13p of the piezoelectric element 13 is an end portion on the diaphragm 12 side in the expansion / contraction direction of the piezoelectric element 13.

The second end portion 13q of the piezoelectric element 13 is connected to the preload spring 14. That is, the second end portion 13q of the piezoelectric element 13 is fixed to the preload spring 14. The preload spring 14 may be directly fastened to the second end portion 13q of the piezoelectric element 13, or may be connected via an adhesive such as an epoxy resin.

The piezoelectric element 13 has a plurality of piezoelectric bodies 13a, a plurality of internal electrodes 13b, and a pair of side electrodes 13c and 13c. The piezoelectric bodies 13a and the internal electrodes 13b are alternately laminated. Each piezoelectric body 13a is composed of piezoelectric ceramics such as lead zirconate titanate (PZT). Each internal electrode 13b is electrically connected to one of a pair of side electrodes 13c and 13c. That is, the internal electrode 13b electrically connected to one side electrode 13c is electrically insulated from the other side electrode 13c. Such a structure is generally referred to as a partial electrode structure. However, the piezoelectric element 13 may include at least one piezoelectric body and a pair of electrodes, and various well-known piezoelectric elements can be used as the piezoelectric element 13.

The piezoelectric element 13 vibrates in response to a drive voltage signal (that is, a drive pulse) applied from the control unit 16 described later. Specifically, when a drive voltage signal is applied from the control unit 16 to the pair of side electrodes 13c and 13c, each piezoelectric body 13a expands and contracts. Pressurized vibration is applied to the diaphragm 12 as the piezoelectric bodies 13a expand and contract.

(4) Preload spring 14 The preload spring 14 is located above the piezoelectric element 13. The preload spring 14 is arranged so as to be sandwiched between the piezoelectric element 13 and the fixing member 15.

The first end portion 14p of the preload spring 14 opposite to the piezoelectric element 13 is connected to the fixing member 15. That is, the first end portion 14p of the preload spring 14 is fixed to the fixing member 15. Therefore, the first end portion 14p of the preload spring 14 is a fixed end. The first end portion 14p of the preload spring 14 may be directly fastened to the fixing member 15, or may be connected to the fixing member 15 via an adhesive such as an epoxy resin. The first end portion 14p of the preload spring 14 is an end portion on the side opposite to the piezoelectric element 13 in the expansion / contraction direction of the piezoelectric element 13.

The second end portion 14q of the preload spring 14 on the piezoelectric element 13 side is connected to the first end portion 13p of the piezoelectric element 13. That is, the second end portion 14q of the preload spring 14 is fixed to the first end portion 13p of the piezoelectric element 13. Therefore, in the present embodiment, the first end portion 13p of the piezoelectric element 13 is not a fixed end. The second end portion 14q of the preload spring 14 may be directly fastened to the piezoelectric element 13, or may be connected to the piezoelectric element 13 via an adhesive such as an epoxy resin. The second end portion 14q of the preload spring 14 is an end portion on the piezoelectric element 13 side in the expansion / contraction direction of the piezoelectric element 13.

FIG. 1 shows a case where a coil spring is used as the preload spring 14, but the present invention is not limited to this. As the preload spring 14, a well-known spring such as a disc spring, a leaf spring, or a spiral spring can be used.

Further, the fixing member 15 may be formed of an elastic member, whereby the function of the preload spring 14 may be exerted. In this case, the fixing member 15 plays a functional role as the preload mechanism without the need for the component of the preload spring 14, and the number of parts and the size can be reduced.

An example of this configuration is shown in FIG. In FIG. 2, the fixing member 18 has a structure having elasticity, and the piezoelectric element 13 is preloaded by fixing the second end portion 13q of the piezoelectric element 13 on the side opposite to the diaphragm 12 to the fixing member 18. Give and hold. The fixing member 18 of FIG. 2 is made to have a desired spring constant by partially reducing the thickness of the piezoelectric element 13 in the expansion / contraction direction. Of course, regardless of this, it is also effective to use a material having appropriate elasticity. Further, in FIG. 2, the fixing member 18 is supported by a support portion 19 located above the liquid agent storage portion 11, but the method for supporting the fixing member 18 is not limited to this.

The spring constant of the preload spring 14 is preferably larger than the spring constant of the diaphragm 12. As a result, the expansion / contraction force of the piezoelectric element 13 can be suppressed from being transmitted to the preload spring 14 side (that is, the upward direction in FIG. 1), and the expansion / contraction force of the piezoelectric element 13 can be efficiently transmitted to the diaphragm 12. Specifically, the piezoelectric element 13 sandwiched between the preload spring 14 and the diaphragm 12 is compressed by the two springs and fits in a balanced position, and the diaphragm 12 is slightly bent toward the pressure chamber 11c. Therefore, the preload spring 14 is in a compressed state as compared with the initial state. When the piezoelectric element 13 is extended in this state, the spring constant of the preload spring 14 is larger than the spring constant of the diaphragm 12, so that the displacement on the diaphragm 12 side becomes large, the pressing force on the pressure chamber 11c can be increased, and the driving efficiency is increased. Can be done.

The preload spring 14 presses the piezoelectric element 13 against the diaphragm 12. The preload spring 14 presses the piezoelectric element 13 against the diaphragm 12 regardless of whether the piezoelectric element 13 is in the expanded state or the contracted state. However, when the second end portion 13q of the piezoelectric element 13 is connected to the diaphragm 12 and the piezoelectric element 13 is in the contracted state, the pressing force from the preload spring 14 to the piezoelectric element 13 is "0". There may be.

Here, as shown in FIG. 3, when the first end portion 13p of the piezoelectric element 13 is in contact with the diaphragm 12, when the stretched piezoelectric element 13 contracts, the inside of the piezoelectric element 13 is pulled by expansion. Not only is force generated, but the piezoelectric element 13 itself may ring. However, in the present embodiment, as described above, the piezoelectric element 13 can be pressed against the diaphragm 12 by the pressing force of the preload spring 14. Therefore, the tensile force generated in the piezoelectric element 13 can be suppressed, and the ringing of the piezoelectric element 13 can be suppressed.

Further, when the first end portion 13p of the piezoelectric element 13 is in contact with the diaphragm 12, when the contracted piezoelectric element 13 expands, if the piezoelectric element 13 is separated from the diaphragm 12, the piezoelectric element 13 itself expands. The force may damage the inside of the piezoelectric element 13. Specifically, there is a risk that the laminated portion will be peeled off, the electrodes and wiring will be broken, and the like. However, in the present embodiment, as described above, the piezoelectric element 13 can be pressed against the diaphragm 12 by the pressing force of the preload spring 14. Therefore, it is possible to prevent the inside of the piezoelectric element 13 from being damaged.

On the other hand, as shown in FIG. 4, when the second end portion 13q of the piezoelectric element 13 is connected to the diaphragm 12, when the stretched piezoelectric element 13 contracts, the contraction speed of the piezoelectric element 13 is the return speed of the diaphragm 12. Since it is faster than the above, a tensile force is applied from the diaphragm 12 to the piezoelectric element 13. As a result, the piezoelectric element 13 may be peeled off from the diaphragm 12, or the inside of the piezoelectric element 13 may be damaged. However, in the present embodiment, as described above, the piezoelectric element 13 can always be pressed against the diaphragm 12 by the pressing force of the preload spring 14. Therefore, it is possible to prevent the piezoelectric element 13 from peeling off or the inside of the piezoelectric element 13 from being damaged.

(5) Fixing member 15 The fixing member 15 is a member that fixes the first end portion 14p of the preload spring 14. The fixing member 15 is located above the liquid agent storage portion 11. However, the fixing member 15 may be separated from the liquid agent storage portion 11 as long as the first end portion 14p of the preload spring 14 can be fixed. Further, the shape of the fixing member 15 is not limited to the shape shown in FIG. 1, and can be appropriately changed in consideration of the arrangement relationship with the peripheral members.

Further, as described above, the fixing member 15 may be formed of an elastic member, whereby the function of the preload spring 14 may be exerted (see the fixing member 18 in FIG. 2).

(6) Control unit 16 The control unit 16 includes a microprocessor such as a CPU (Central Processing Unit) and a DSP (Digital Signal Processor), an arithmetic unit such as an ASIC (Application Specific Integrated Circuit), and a power MOSFET (Metal-Oxide). -It is realized by a power amplifier composed of Semiconductor Field-Effect Transistor).

The control unit 16 generates a drive voltage signal for driving the piezoelectric element 13. The control unit 16 sends the generated drive voltage signal to the power amplifier to amplify the electric power, and applies this to each of the pair of side electrodes 13c and 13c of the piezoelectric element 13 to vibrate the piezoelectric element 13.

(Other Embodiments) Although the present invention has been described in accordance with the above embodiments, the statements and drawings that form part of this disclosure should not be understood to limit the invention. Various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art from this disclosure.

In the above embodiment, the piezoelectric element 13 has been described as an example of the “driving unit” that vibrates the diaphragm 12, but the “driving unit” may include a member other than the piezoelectric element 13.

For example, the "driving unit" may include a horn for increasing the vibration amplitude of the piezoelectric element 13. For the horn, for example, a cylindrical metal rod can be used. The vibration amplitude of the piezoelectric element 13 can be increased by setting the natural vibration frequency of the horn to be equal to or less than the drive limit frequency of the piezoelectric element 13 and making the natural vibration frequency and the frequency of the drive voltage signal a multiple relationship. The natural vibration frequency is the frequency at which the horn vibrates freely. The drive limit frequency is the maximum value of the limit frequency at which the piezoelectric element 13 can be driven with a stable amplitude.

Further, the "driving unit" may include a piezoelectric element for vibration for vibrating the diaphragm 12 at a high frequency. The excitation piezoelectric element vibrates in response to a high frequency signal having a higher frequency than the drive voltage signal applied to the piezoelectric element 13. By applying a minute pressurizing vibration to the diaphragm 12 so that the liquid agent is not discharged from the discharge port 11e, the fluidity of the liquid agent stored in the liquid agent storage unit 11 is improved, and the liquid agent liquid discharged from the discharge port 11e is improved. The sharpness can be improved.

In the above embodiment, the first end 13p of the piezoelectric element 13 is directly in contact with or connected to the diaphragm 12, but the piezoelectric element 13 and the surface are between the first end 13p and the diaphragm 12. An intermediate member that comes into contact with the diaphragm 12 and makes point contact with the diaphragm 12 may be sandwiched. The intermediate member is fixed to the first end portion 13p of the piezoelectric element 13 and can be attached to and detached from the diaphragm 12. By sandwiching such an intermediate member, it is possible to prevent the pressure from being concentrated on a part of the first end portion 13p of the piezoelectric element 13, so that damage to the piezoelectric element 13 can be further suppressed.

10 Liquid agent coating device 11 Liquid agent storage unit 11a Housing 11b Nozzle 11c Pressure chamber 11d Liquid agent supply port 11e Discharge port 12 Diaphragm 13 Piezoelectric element 14 Preload spring 15 Fixing member 16 Control unit

Claims (7)

A liquid agent having a liquid agent storage unit having a liquid agent discharge port, a diaphragm for changing the internal volume of the liquid agent storage unit, a drive unit located on the diaphragm, and a preload mechanism located on the drive unit. Coating device. The liquid agent coating device according to claim 1, wherein the end of the preload mechanism opposite to the driving portion is a fixed end. The liquid agent coating device according to claim 1 or 2, wherein the driving unit is in contact with the diaphragm. The liquid agent coating device according to any one of claims 1 to 3, wherein the driving unit is connected to the diaphragm. The liquid agent coating device according to any one of claims 1 to 4, wherein the spring constant of the preload mechanism is larger than the spring constant of the diaphragm. The liquid agent coating device according to any one of claims 1 to 5, further comprising a fixing member to which an end portion of the preload mechanism opposite to the drive portion is fixed, wherein the preload mechanism is a preload spring. The preload mechanism is a fixing member to which an end portion of the driving portion opposite to the diaphragm is fixed, and the fixing member is composed of an elastic member, according to any one of claims 1 to 5. Liquid application device.

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