JPWO2018180006A1 - Droplet ejection device - Google Patents

Abstract

An object of the present invention is to provide a droplet discharge device capable of increasing a displacement amount while maintaining responsiveness of a piezoelectric element. A droplet discharge device includes a liquid storage unit having a liquid discharge port, a diaphragm configured to change the volume of the liquid storage unit, a receiving member fixed to the diaphragm, and a receiving member. And a piezoelectric element 14 for applying pressure vibration to the piezoelectric element. The piezoelectric element 14 is not fixed or fastened to the receiving member 13.

Description

The present invention relates to a droplet discharge device.

A piezoelectric element that performs energy conversion from electrical energy to mechanical energy by the piezoelectric effect has excellent responsiveness. In a wide range of fields, such as semiconductors, printing, and chemicals, a liquid droplet is discharged onto a surface of an object in a liquid field. Used in equipment.

Here, in order to increase the amount of displacement of the piezoelectric element, a method of providing a displacement enlarging mechanism using a hinge structure has been proposed (see Patent Documents 1 and 2).

Patent Document 1: Japanese Patent Application Laid-Open No. 2005-349387 Patent Document 2: Japanese Patent Application Laid-Open No. 2008-54492

However, in the methods of Patent Literatures 1 and 2, since the displacement of the piezoelectric element needs to be increased through a hinge structure, the response of the piezoelectric element is impaired.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a droplet discharge device capable of increasing the amount of displacement while maintaining the responsiveness of a piezoelectric element.

One aspect of the droplet discharge device of the present invention is a liquid storage unit having a liquid discharge port, a diaphragm that changes the volume of the liquid storage unit, a receiving member fixed to the diaphragm, and pressure vibration applied to the receiving member. And a piezoelectric element to be added. The piezoelectric element is not fixed or fastened to the receiving member.

According to one aspect of the present invention, it is possible to provide a droplet discharge device capable of increasing the amount of displacement while maintaining the responsiveness of the piezoelectric element.

Schematic diagram showing the configuration of the droplet discharge device according to the first embodiment 4 is a graph showing displacement waveforms of the diaphragm and the piezoelectric element according to the first embodiment. Schematic diagram for explaining states of the diaphragm and the piezoelectric element according to the first embodiment. Schematic diagram for explaining states of the diaphragm and the piezoelectric element according to the first embodiment. Schematic diagram for explaining states of the diaphragm and the piezoelectric element according to the first embodiment. Schematic diagram showing the configuration of the droplet discharge device according to the second embodiment 4 is a graph showing displacement waveforms of a diaphragm and a piezoelectric element according to a second embodiment. 4 is a graph showing displacement waveforms of a diaphragm and a piezoelectric element according to a second embodiment. 4 is a graph showing displacement waveforms of a diaphragm and a piezoelectric element according to a second embodiment.

Hereinafter, an appearance inspection apparatus according to an 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 number of each structure may be different from the scale and number of the actual structure in order to make each configuration easy to understand.

In this specification, the term “perpendicular” is a concept that includes not only a vertical case in a physically strict sense but also a substantially vertical case. The term “substantially vertical” refers to a case where it is inclined within a range of 15 ° or less.

1. First Embodiment (Configuration of Droplet Discharge Apparatus 10) FIG. 1 is a schematic diagram illustrating a configuration of a droplet discharge apparatus 10 according to a first embodiment.

The droplet discharge device 10 includes a liquid storage unit 11, a diaphragm 12, a receiving member 13, a piezoelectric element 14, a contact member 15, and a control unit 16.

(1) Liquid Storage Unit 11 The liquid storage unit 11 has a main body 11a, a liquid chamber 11b, and a liquid discharge port 11c.

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

The liquid chamber 11b is formed inside the main body 11a. The liquid is stored in the liquid chamber 11b. Examples of the liquid include a solder, a thermosetting resin, ink, and a coating liquid for forming a functional thin film (such as an alignment film, a resist, a color filter, and organic electroluminescence).

The liquid discharge port 11c is formed so as to penetrate the main body 11a. In the present embodiment, the liquid ejection port 11c is formed at a position facing the diaphragm 12, but is not limited to this. The liquid in the liquid chamber 11b is discharged to the outside as liquid droplets from the liquid discharge port 11c. Although not shown in FIG. 1, the liquid storage section 11 has a liquid supply port for supplying liquid to the liquid chamber 11b.

(2) Diaphragm 12 The diaphragm 12 is disposed on the liquid storage unit 11. The diaphragm 12 seals the liquid chamber 11b of the liquid storage unit 11. The diaphragm 12 elastically vibrates together with the receiving member 13 when pressure vibration is applied to the receiving member 13 from a piezoelectric element 14 described later. Thereby, the diaphragm 12 changes the volume of the liquid chamber 11b.

The diaphragm 12 has a fixed part 12a and a flexible part 12b. The fixing section 12a is fixed to the main body 11a of the liquid storage section 11. The fixing portion 12a is an outer edge of the diaphragm 12. The flexible portion 12b is a portion surrounded by the fixing portion 12a. The flexible part 12b is not fixed to the main body part 11a of the liquid storage part 11, and is deformable.

When the flexible portion 12b curves convexly toward the inside of the liquid chamber 11b, the volume of the liquid chamber 11b becomes small. As a result, the liquid is discharged to the outside as liquid droplets from the liquid discharge port 11c. Thereafter, when the flexible portion 12b returns to the state of FIG. 1 due to its own elasticity, the volume of the liquid chamber 11b returns to the original state. At this time, the liquid is supplied to the liquid chamber 11b from the liquid supply port.

Although the material constituting the diaphragm 12 is not particularly limited, for example, an alloy material, a ceramic material, a synthetic resin material, or the like can be used.

(3) Receiving Member 13 The receiving member 13 is fixed to the outer surface 12S of the flexible portion 12b of the diaphragm 12. The receiving member 13 can be fastened to the flexible portion 12b by an adhesive or by welding.

Pressing vibration is applied to the receiving member 13 from a piezoelectric element 14 described later. When the pressure vibration is applied, the receiving member 13 functions as a weight of the diaphragm 12 and urges the diaphragm 12 with an inertial force. As a result, the diaphragm 12 can be largely displaced as compared with the case where the receiving member 13 is not provided. The displacement of the diaphragm 12 will be described later in detail.

The material forming the receiving member 13 is not particularly limited, but it is preferable to use a material having excellent impact resistance and abrasion resistance in order to suppress breakage or wear due to contact with the contact member 15 described below. Examples of such a material include ceramic materials such as zirconia and silicon nitride (silicon nitride). A material having excellent impact resistance and abrasion resistance is used for a portion of the receiving member 13 which comes into contact with the contact member 15, and a material having a relatively high density is used for other portions to secure weight as a weight. (Such as stainless steel alloy and brass) may be used.

The size of the receiving member 13 is not particularly limited. However, since the region of the flexible portion 12b to which the receiving member 13 is fixed is unlikely to bend, the size of the receiving member 13 is appropriately adjusted so as to secure the amount of bending of the flexible portion 12b. Adjustment is preferred.

Specifically, in a direction parallel to the outer surface 12S of the flexible portion 12b (hereinafter, referred to as a "first direction"), the width W1 of the receiving member 13 is preferably 60% or less of the width W2 of the flexible portion 12b. , 50% or less, more preferably 30% or less. For example, when the flexible portion 12b is a disk having a diameter of 10 mm, it is preferable to arrange a columnar receiving member 13 having a diameter of 6 mm or less at the center of the outer surface 12S. Thereby, since an annular flexible region can be left in the flexible portion 12b, the amount of bending of the diaphragm 12 can be secured.

(4) Piezoelectric element 14 The piezoelectric element 14 is arranged to face the receiving member 13. In the present embodiment, the piezoelectric element 14 is separated from the receiving member 13 in the second direction, and is not fixed or fastened to the receiving member 13. The base end portion 14p of the piezoelectric element 14 is fixed to a fixing member 19 and is a fixed end. A contact member 15 described below is fixed to the tip end portion 14q of the piezoelectric element 14, and is a free end.

The piezoelectric element 14 has a plurality of piezoelectric bodies 14a, a plurality of internal electrodes 14b, and a pair of side electrodes 14c. Each piezoelectric body 14a and each internal electrode 14b are alternately stacked. Each piezoelectric body 14a is made of a piezoelectric ceramic such as lead zirconate titanate (PZT). Each of the inner electrodes 14b is electrically connected to one of the pair of side electrodes 14c. That is, the internal electrode 14c electrically connected to the one side electrode 14c is electrically insulated from the other side electrode 14c. Such a structure is generally called a partial electrode structure.

However, the piezoelectric element 14 only needs to include at least one piezoelectric body and a pair of electrodes, and various known piezoelectric elements can be applied to the piezoelectric element 14.

The piezoelectric element 14 expands and contracts in a direction perpendicular to the first direction (hereinafter, referred to as a “second direction”) in response to application of a voltage. Specifically, the piezoelectric element 14 has a natural length when no voltage is applied to the pair of side electrodes 14c. The piezoelectric element 14 expands toward the receiving member 13 as the voltage applied to the pair of side electrodes 14c, 14c increases. Then, when a drive voltage (that is, the highest potential) is applied to the pair of side electrodes 14c, 14c, the piezoelectric element 14 is in a state of being extended most toward the receiving member 13 side.

With the extension operation of the piezoelectric element 14, a pressure vibration is applied to the receiving member 13 in the non-restrained state. The non-restrained state means a state where the receiving member 13 is not fixed or fastened to the piezoelectric element 14 and the receiving member 13 can move independently of the piezoelectric element 14.

When the voltage applied to the pair of side electrodes 14c, 14c becomes smaller than the driving voltage, the piezoelectric element 14 contracts toward the opposite side of the receiving member 13 and returns to the natural length state.

(5) Contact Member 15 The contact member 15 is inserted between the receiving member 13 and the piezoelectric element 14. The contact member 15 is fixed to the tip 14q of the piezoelectric element 14. The contact member 15 can be fastened to the piezoelectric element 14 by an adhesive or by welding. The contact member 15 moves in the second direction together with the piezoelectric element 14 as the piezoelectric element 14 expands and contracts.

The contact member 15 is not fixed or fastened to the receiving member 13. The contact member 15 contacts the receiving member 13 in a freely detachable manner.

The contact member 15 has a curved surface 15S and a flat surface 15T. The curved surface 15S faces the outer surface 13S of the receiving member 13. The plane 15T is connected to the end face 14S of the piezoelectric element 14. Therefore, the contact member 15 makes a point contact with the receiving member 13 and makes a surface contact with the piezoelectric element 14. Therefore, the force applied from the receiving member 13 to the contact member 15 is evenly transmitted to the piezoelectric element 14 via the contact member 15. As a result, it is possible to prevent the compressive stress from concentrating inside the piezoelectric element 14 and breakage.

In the present embodiment, the contact member 15 is formed in a substantially hemispherical shape, but is not limited to this. The contact member 15 may have any shape as long as it can make point contact with the receiving member 13 and make surface contact with the piezoelectric element 14.

The material forming the contact member 15 is not particularly limited. However, in order to suppress breakage or wear due to collision with the receiving member 13, a material having excellent impact resistance and abrasion resistance is used similarly to the receiving member 13. Is preferred. A material having excellent impact resistance and abrasion resistance may be used for a portion of the contact member 15 that comes into contact with the receiving member 13, and a material having a relatively high density may be used for other portions.

(6) Control Unit 16 The control unit 16 includes a microprocessor such as a CPU (Central Processing Unit) or a DSP (Digital Signal Processor), or an ASIC (Appl.
communication specific integrated circuit).

The control unit 16 generates a drive pulse for expanding and contracting the piezoelectric element 14, and applies a voltage to the pair of side electrodes 14c of the piezoelectric element 14 based on the generated drive pulse. The control unit 16 can appropriately set the highest potential (i.e., the drive voltage) and the waveform of the drive pulse.

(Operation of Droplet Discharge Apparatus 10) Next, the operation of the droplet discharge apparatus 10 will be described with reference to the drawings.

FIG. 2 is a graph showing changes in the displacement D of the diaphragm 12 and the displacement E of the piezoelectric element 14. FIGS. 3 to 5 are schematic diagrams for explaining the states of the diaphragm 12 and the piezoelectric element 14 at times T1 to T3. The transition of the displacement amount D of the diaphragm 12 refers to a displacement waveform of the diaphragm 12. The transition of the displacement E of the piezoelectric element 14 is the same as the waveform of the drive pulse generated by the control unit 16.

The control unit 16 has not applied a voltage to the piezoelectric element 14 at time T0. Therefore, at time T0, the piezoelectric element 14 is not extended, and no pressure vibration is applied to the receiving member 13 (see FIG. 1). At time T0, the volume of the liquid storage unit 11 is the maximum.

The control unit 16 gradually increases the voltage applied to the piezoelectric element 14 at times T0 to T1, and applies the highest potential (drive voltage) at time T1. Therefore, at times T0 to T1, the piezoelectric element 14 expands from the displacement amount 0 to the maximum displacement amount Emax, and the diaphragm 12 is urged by the piezoelectric element 14 to move together with the piezoelectric element 14 to the first displacement amount Da ( (See FIG. 3). The first displacement Da of the diaphragm 12 is the same as the maximum displacement Emax of the piezoelectric element 14.

The control unit 16 gradually lowers the voltage applied to the piezoelectric element 14 from time T1 to T2, and returns to a state where no voltage is applied at time T2. Therefore, between times T1 and T2, the piezoelectric element 14 contracts from the maximum displacement amount Emax to the displacement amount 0 (see FIG. 4). On the other hand, at times T1 to T2, the diaphragm 12 is further displaced from the first displacement Da to the second displacement Db (> Da) by being urged by the inertial force of the receiving member 13 functioning as a weight. (See FIG. 4).

The control unit 16 has not applied a voltage to the piezoelectric element 14 between times T2 and T3. Therefore, the displacement of the piezoelectric element 14 is maintained at 0 (see FIG. 5). On the other hand, also at times T2 to T3, the diaphragm 12 is further displaced from the second displacement Db to the maximum displacement Dmax (> Db) by being further urged by the inertial force of the receiving member 13 functioning as a weight. (See FIG. 5). The maximum displacement Dmax of the diaphragm 12 is larger than the maximum displacement Emax of the piezoelectric element 14. At time T3, the volume of the liquid storage unit 11 is the minimum.

The controller 16 has not applied a voltage to the piezoelectric element 14 after time T3, but as shown in FIG. 2, the diaphragm 12 is in a state in which it is not bent at time T4 (hereinafter, referred to as an “original state”). After returning, the amount of displacement approaches zero while damping and vibrating at a natural frequency corresponding to its own elasticity. Therefore, in the displacement waveform of the diaphragm 12, after the first wave, continuous or transient second to n-th waves (hereinafter, referred to as "ringing") are generated.

(Features) (1) In the droplet discharge device 10, the diaphragm 12 is provided with the receiving member 13 functioning as a weight. Therefore, after the piezoelectric element 14 is displaced to the maximum displacement amount Emax, the diaphragm 12 can be displaced to the maximum displacement amount Dmax by being urged by the inertial force of the receiving member 13. Therefore, a large force can be applied to the liquid stored in the liquid storage unit 11. As a result, even if the liquid has a high viscosity, the liquid can be discharged smoothly without providing a heating mechanism (see JP-A-2003-103207 and JP-A-2000-317371). Further, since the pressurized vibration from the piezoelectric element 14 can be directly applied to the diaphragm 12, a displacement enlarging mechanism using a hinge structure (see JP-A-2005-349387 and JP-A-2008-54492). Responsiveness can be improved as compared with the case where the device is provided. As described above, according to the droplet discharge device 10 according to the first embodiment, the displacement of the diaphragm 12 can be increased while the responsiveness of the piezoelectric element 14 is maintained.

(2) In the droplet discharge device 10, the contact member 15 includes the contact member 15 fixed to the piezoelectric element 14 and in contact with the receiving member 13 in a detachable manner. Therefore, it is possible to suppress the piezoelectric element 14 itself from being damaged or worn as compared with the case where the piezoelectric element 14 contacts the receiving member 13. In addition, since the contact member 15 is not fixed to the receiving member 13, the non-restricted state of the receiving member 13 can be maintained.

(3) The contact member 15 is in point contact with the receiving member 13 and is in surface contact with the piezoelectric element 14. Therefore, since the force applied from the receiving member 13 to the contact member 15 can be evenly transmitted to the piezoelectric element 14, it is possible to prevent the compressive stress from being concentrated inside the piezoelectric element 14 and to be damaged.

2. Second Embodiment A configuration of a droplet discharge device 20 according to a second embodiment will be described.

In the droplet discharge device 10 according to the first embodiment, ringing occurs after the first wave in the displacement waveform of the diaphragm 12, but in the droplet discharge device 20 according to the second embodiment, (Hereinafter, referred to as “ringing suppression control”) is executed. Hereinafter, differences from the first embodiment will be mainly described.

(Configuration of Droplet Discharge Apparatus 20) FIG. 6 is a schematic diagram illustrating a configuration of the droplet discharge apparatus 20. The droplet discharge device 20 includes a strain gauge 17 and an amplifier device 18 in addition to the configuration of the droplet discharge device 10 described above.

The strain gauge 17 is provided on the outer surface 12S of the flexible portion 12b of the diaphragm 12. The strain gauge 17 detects the amount of distortion of the flexible part 12b according to the increase or decrease of the resistance value of the flexible part 12b. The strain gauge 17 is an example of a “displacement gauge” for detecting a displacement waveform (transitional change of displacement) of the diaphragm 12. The strain gauge 17 outputs the detected strain amount to the amplifier device 18. The amplifier device 18 amplifies the amount of distortion input from the strain gauge 17 and outputs the amplified amount to the control unit 16.

The control unit 16 acquires a displacement waveform of the diaphragm 12 based on the input distortion amount. The control unit 16 executes the ringing suppression control in the next pressurized vibration based on the displacement waveform of the diaphragm 12 in the previous pressurized vibration.

(Ringing Suppression Control) Hereinafter, an example of the ringing suppression control by the control unit 16 will be described with reference to the drawings. Various methods can be considered as a specific method of the ringing suppression control. In the ringing suppression control described below, based on the displacement waveform of the diaphragm 12 in the previous pressurized vibration, the diaphragm 12 in the next pressurized vibration is used. It is assumed that ringing is suppressed. According to such ringing suppression control, ringing can be gradually suppressed each time pressure vibration of the diaphragm 12 is repeated.

7 to 9 are graphs showing the transition of the displacement D of the diaphragm 12 and the displacement E of the piezoelectric element 14. FIG. The transition of the displacement amount D of the diaphragm 12 is a displacement waveform of the diaphragm 12. The transition of the displacement E of the piezoelectric element 14 is the same as the waveform of the drive pulse generated by the control unit 16.

7 to 9, it is assumed that the diaphragm 12 continuously vibrates three times at predetermined time intervals. In the first pressing vibration M1 shown in FIG. 7, the ringing suppression control is not executed, and in the second pressing vibration M2 shown in FIG. 8, the ringing suppression control is executed based on the displacement waveform of FIG. In the third pressurization vibration M3 shown in FIG. 9, the ringing suppression control is executed based on the displacement waveform of FIG. Hereinafter, the details will be described.

In the first pressurization vibration M1 shown in FIG. 7, the first wave X1 to the n-th wave Xn are included in the displacement waveform of the diaphragm 12, and the second wave X2 to the n-th wave Xn are ringing.

In the second pressurization vibration M2 shown in FIG. 8, the displacement waveform of the diaphragm 12 includes the first wave Y1 to the n-th wave Yn, of which the second wave Y2 to the n-th wave Yn are ringing.

In the third pressurization vibration M3 shown in FIG. 9, the first waveform Z1 to the n-th Zn are included in the displacement waveform of the diaphragm 12, and the second wave Z2 to the n-th Zn are ringing.

(First Pressing Vibration M1) The first pressing vibration M1 is the same as the pressurizing vibration described with reference to FIG. 2 in the first embodiment. The control unit 16 controls the piezoelectric element 14 by a drive pulse having a voltage rising section from time T0 to T1 and a voltage falling section from time T1 to T2.

Therefore, the voltage applied to the piezoelectric element 14 increases from 0 (reference potential) to the drive voltage (maximum potential) at times T0 to T1, and then decreases from the drive voltage to 0 at times T1 to T2.

As shown in FIG. 7, in the first pressurization vibration M1, in the voltage drop section from time T1 to T2, LE1 indicating the displacement of the piezoelectric element 14 does not intersect with the line segment LD1 indicating the displacement of the diaphragm 12. . Therefore, since the diaphragm 12 does not contact the contact member 15 until the diaphragm 12 returns to the original state at the time T4, the ringing remains.

(Second Pressing Vibration M2) Next, the control unit 16 acquires the displacement waveform in FIG. Then, the control unit 16 determines the voltage decreasing timing and the voltage decreasing speed (slope) so that the ringing included in the displacement waveform of FIG. 7 is reduced, and adjusts the waveform of the drive pulse based on the timing. .

Specifically, as shown in FIG. 8, the control unit 16 generates a drive pulse having a voltage rising section between times T5 and T6, a voltage maintaining section between times T6 and T7, and a voltage falling section between times T7 and T8. This controls the piezoelectric element 14.

Therefore, the voltage applied to the piezoelectric element 14 rises from 0 (reference potential) to the drive voltage (maximum potential) at times T5 to T6, and is maintained at the drive voltage at times T6 to T7, and then at times T7 to T8. In this case, the drive voltage drops from 0 to 0. The time width of the voltage maintaining section between times T6 and T7 is TW1.

As shown in FIG. 8, in the second pressurization vibration M2, in the voltage drop section from time T7 to T8, LE2 indicating the displacement of the piezoelectric element 14 intersects with the line segment LD2 indicating the displacement of the diaphragm 12. . This means that the diaphragm 12 is in contact with the contracting abutting member 15 during the return to the original state between the times T7 and T8.

For this reason, the vibration of the diaphragm 12 is absorbed by the contraction of the contact member 15, so that the ringing in FIG. 8 is reduced as compared with the ringing in FIG.

(Third Pressing Vibration M3) Next, the control unit 16 acquires the displacement waveform in FIG. Then, the control unit 16 determines the timing of decreasing the voltage and the decreasing speed (gradient) of the voltage so that the ringing included in the displacement waveform of FIG. 8 is further reduced, and further changes the waveform of the drive pulse based on the timing. adjust.

Specifically, as shown in FIG. 9, the control unit 16 generates a drive pulse having a voltage rising section from time T9 to T10, a voltage maintaining section from time T10 to T11, and a voltage falling section from time T11 to T12. This controls the piezoelectric element 14. Therefore, the voltage applied to the piezoelectric element 14 rises from 0 (reference potential) to the drive voltage (maximum potential) from time T9 to T10, and is maintained at the drive voltage from time T10 to T11, and then from time T11 to T12. In this case, the drive voltage drops from 0 to 0. The time width TW2 of the voltage maintaining section at times T10 to T11 is longer than the time width TW1 of the voltage maintaining section at times T6 to T7 of the second pressurization vibration M2.

As shown in FIG. 9, in the third pressurization vibration M3, in the voltage drop section from time T10 to T11, LE3 indicating the displacement of the piezoelectric element 14 intersects with the line segment LD3 indicating the displacement of the diaphragm 12. . Therefore, the diaphragm 12 is in contact with the contracting contact member 15 during the return to the original state at the times T11 to T12.

Further, since the time width TW2 of the voltage maintaining section is set longer than the time width TW1, the timing at which the diaphragm 12 contacts the contact member 15 is slightly delayed. Therefore, the vibration of the diaphragm 12 is absorbed by the contraction of the contact member 15, so that the ringing in FIG. 9 is further reduced as compared with the ringing in FIG.

(Fourth Pressing Vibration) The third pressurizing vibration has been described above, but the same ringing suppression control may be continuously executed after the fourth pressing vibration. Alternatively, the drive pulse when the maximum displacement of the ringing becomes less than the predetermined value is continuously used thereafter, and the ringing suppression control is restarted when the maximum displacement of the ringing becomes more than the predetermined value. Good.

(Characteristics) (1) In the droplet discharge device 20, the control unit 16 applies a driving voltage to the piezoelectric element 14 in the second pressurization vibration M2, and then controls the ringing at times T7 to T8 so as to reduce ringing. The ringing suppression control is being executed. Therefore, it is possible to limit the amount of liquid that is discharged as liquid droplets from the liquid discharge port 11c to the outside, and it is possible to discharge liquid droplets with high definition.

(2) In the droplet discharge device 20, the control unit 16 controls the times T11 to T11 so that the ringing z2 to zn in the third pressurization vibration M3 is further reduced than the ringing in the second pressurization vibration M2. At T12, the ringing suppression control is improved. Therefore, the amount of liquid discharged from the liquid discharge port 11c as liquid droplets to the outside can be further restricted, so that liquid droplets can be discharged with higher definition.

(Other Embodiments) Although the present invention has been described by the above embodiments, it should not be understood that the description and drawings forming part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples, and operation techniques will be apparent to those skilled in the art.

In the first and second embodiments, the contact member 15 is interposed between the diaphragm 12 and the piezoelectric element 14, but the contact member 15 may not be interposed. In this case, the receiving member 13 comes into direct contact with the piezoelectric element 14. When the receiving member 13 comes into direct contact with the piezoelectric element 14, it is preferable that the receiving member 13 makes point contact with the piezoelectric element 14.

In the first and second embodiments, the contact member 15 has the curved surface 15S that makes point contact with the receiving member 13, but is not limited to this. The contact member 15 only needs to be in point contact with the receiving member 13. For example, when the receiving member 13 has a curved surface, the contact member 15 may be flat.

In the first and second embodiments, the contact member 15 is formed in a substantially hemispherical shape, and the whole is inserted between the receiving member 13 and the piezoelectric element 14, but is not limited thereto. Not something. The contact member 15 may be partially inserted between the receiving member 13 and the piezoelectric element 14. For example, the contact member 15 may be a box-shaped container that stores the piezoelectric element 14. In this case, the bottom plate of the container sandwiched between the receiving member 13 and the piezoelectric element 14 functions as a contact member.

Although not specifically mentioned in the first and second embodiments, the second direction in which the piezoelectric element 14 expands and contracts may be a vertical direction or a direction intersecting the vertical direction. That is, the expansion and contraction direction of the piezoelectric element 14 can be freely set regardless of the vertical direction. Therefore, the diaphragm 12 may be disposed on the side surface of the liquid storage unit 11 or may be disposed on the bottom surface of the liquid storage unit 11.

In the second embodiment, the control unit 16 executes the ringing suppression control so as to reduce all of the ringing in the second and third pressurization vibrations M2 and M3, but is not limited thereto. is not. The control unit 16 may execute the ringing suppression control so that a part of the ringing is not reduced. In this way, for example, by leaving the second wave and the third wave without reducing them, the volume of the droplet can be increased.

In the above-described second embodiment, the droplet discharge device 20 determines the voltage reduction timing and the voltage reduction speed of the diaphragm 12 each time in the ringing suppression control. However, the present invention is not limited to this. For example, the voltage decrease timing and the voltage decrease speed determined based on the first displacement waveform may be continuously used thereafter. In this case, the time when the displacement of the diaphragm 12 becomes equal to or less than a predetermined value may be set as the voltage decrease timing.

In the second embodiment, the droplet discharge device 20 includes the strain gauge 17 and the amplifier device 18 in order to execute the ringing suppression control. However, the droplet discharge device 20 may not include the strain gauge 17 and the amplifier device 18. Ringing suppression control can be executed. For example, if a displacement waveform of the diaphragm 12 when a desired liquid is used is obtained in advance and a drive pulse capable of suppressing ringing is determined, the control unit 16 does not need to adjust the drive pulse. The gauge 17 and the amplifier device 18 are unnecessary.

In the second embodiment, the control unit 16 adjusts the time width of the voltage maintaining section, that is, the timing of decreasing the voltage in the third pressurization oscillation M3, but is not limited to this. Absent. The control unit 16 can also adjust the amount of reduction in ringing by adjusting the rate of decrease in voltage (decrease potential per unit time). Adjusting the voltage decreasing rate specifically means changing the falling slope by changing the time from T7 to T8 in FIG. 8 and T11 to T12 in FIG. Further, the control unit 16 can also adjust the amount of reduction in ringing by adjusting both the timing of decreasing the voltage and the rate of decrease of the voltage.

In the second embodiment, the control unit 16 executes the ringing suppression control based on the displacement amount of the diaphragm 12 in the first and second pressurizing vibrations M1 and M2, but is not limited thereto. Absent. The control unit 16 can execute the ringing suppression control by using a predetermined drive pulse preset for the ringing suppression control. In this case, the droplet discharge device 20 need not include the strain gauge 17 and the amplifier device 18.

In the second embodiment, the strain gauge 17 has been described as an example of the displacement gauge for detecting the displacement waveform of the diaphragm 12, but the present invention is not limited to this. As the displacement meter, a shape measuring device or the like for directly measuring the dimensions of the diaphragm 12 can be used.

REFERENCE SIGNS LIST 10 droplet discharge device 11 liquid storage unit 12 diaphragm 13 receiving member 14 piezoelectric element 15 contact member 16 control unit 17 strain gauge

Claims (7)

A liquid storage unit having a liquid discharge port, a diaphragm that changes the volume of the liquid storage unit, a receiving member fixed to the diaphragm, and a piezoelectric element that applies pressure vibration to the receiving member. A droplet discharging device, wherein the element is not fixed to the receiving member. The droplet discharging device according to claim 1, further comprising a contact member that contacts the receiving member, wherein the contact member is fixed to the piezoelectric element and is not fixed to the receiving member. 2. The droplet discharge device according to claim 1, wherein the contact member makes point contact with the receiving member and makes surface contact with the piezoelectric element. 3. A control unit that controls an amount of expansion of the piezoelectric element by applying a voltage to the piezoelectric element, wherein the control unit reduces at least a part of ringing of the diaphragm after applying a voltage to the piezoelectric element. 4. The droplet discharge device according to claim 1, wherein the control device executes ringing suppression control for decreasing the voltage so as to reduce the voltage. 5. The droplet discharge device according to claim 4, wherein the control unit executes the ringing suppression control so as not to reduce a part of the ringing of the diaphragm. 5. The apparatus according to claim 4, further comprising: a displacement meter configured to detect a displacement waveform of the diaphragm, wherein the control unit determines, based on the displacement waveform of the diaphragm, a timing at which a voltage is reduced in the ringing suppression control and a rate at which the voltage is reduced. Or the droplet discharge device according to 5. The control unit, based on a displacement waveform in which ringing has been reduced at the start timing and the reduction speed, changes at least one of a timing at which a voltage is reduced in the next ringing suppression control and a voltage reduction speed. Item 7. A droplet discharge device according to Item 6.

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