CN210041674U

CN210041674U - Actuator driving device

Info

Publication number: CN210041674U
Application number: CN201890000468.2U
Authority: CN
Inventors: 中矶俊幸
Original assignee: Murata Manufacturing Co Ltd
Current assignee: Murata Manufacturing Co Ltd
Priority date: 2017-12-06
Filing date: 2018-09-12
Publication date: 2020-02-07
Anticipated expiration: 2028-09-12
Also published as: WO2019111480A1

Abstract

The utility model provides an actuator driving device. The actuator driving device (111) is provided with an actuator (11) that displaces or deforms in accordance with an applied voltage, and an actuator control circuit (110) that controls the applied voltage to the actuator (11). The actuator control circuit (110) is configured to include: the variable capacitance device comprises a variable capacitance unit (21C) connected to the actuator (11) and determining the capacitance according to a control voltage, a variable capacitance element control circuit (30) applying the control voltage to the variable capacitance unit (21C), and a power supply circuit (40) applying the voltage to a circuit including the actuator (11) and the variable capacitance unit (21C).

Description

Actuator driving device

Technical Field

The present invention relates to an actuator driving device that controls a voltage applied to an actuator that displaces or deforms according to an applied voltage.

Background

Patent document 1 discloses that a variable capacitance element is connected in series to an equivalent capacitance type actuator, a constant voltage source for applying a voltage to the actuator and both ends of the variable capacitance element is provided, and the voltage applied to the actuator is adjusted by changing the capacitance of the variable capacitance element.

Patent document 1: international publication No. 2006/082807

In the actuator driving device described in patent document 1, a variable capacitor connected in series with an equivalent capacitive actuator changes the electrostatic capacitance by mechanically changing the inter-electrode distance or the like, or a fixed capacitor is connected in parallel to a variable capacitive element, and the parallel connection of the fixed capacitors is intermittently switched via a switch, thereby equivalently changing the combined capacitance.

However, in the above-described configuration in which the electrostatic capacitance is mechanically changed, the response is poor, and the actuator cannot be driven at high speed. In addition, in the configuration in which the synthesized capacitance is changed equivalently by intermittently switching through the switch, it is necessary to turn on and off the switch at a frequency higher than the upper limit of the frequency responsiveness of the actuator, and therefore a circuit for controlling the switch is required to have high-speed responsiveness, and the circuit configuration is also complicated and expensive.

The contents of the utility model

Therefore, an object of the present invention is to provide an actuator driving device configured to determine a capacitance electrically by controlling a voltage, thereby allowing a displacement amount or a deformation amount of an actuator to be specified at a high speed.

(1) The actuator driving device of the present invention includes an actuator that displaces or deforms in accordance with an applied voltage, and an actuator control circuit that controls the applied voltage to the actuator.

Further, the actuator control circuit is characterized by comprising: the variable capacitance element is connected to an actuator and determines an electrostatic capacitance according to a control voltage, the variable capacitance element control circuit applies the control voltage to the variable capacitance element, and the power supply circuit applies the voltage to a circuit including the actuator and the variable capacitance element.

According to the above configuration, since the capacitance of the variable capacitance element can be defined at high speed, the actuator can be driven at high speed.

(2) The variable capacitance element includes, for example, at least two capacitor electrodes and a ferroelectric film formed between the two capacitor electrodes, and is a ferroelectric capacitor whose capacitance is determined according to a control voltage value applied between the two capacitor electrodes. According to this configuration, a high capacitance value can be specified without polarity, and the displacement amount or deformation amount of the actuator can be controlled in a wide range.

(3) The variable capacitance element control circuit includes, for example: the voltage dividing circuit includes a resistance voltage dividing circuit based on a plurality of resistance elements having different resistance values, and a voltage dividing ratio setting circuit that sets a voltage dividing ratio of the resistance voltage dividing circuit. Thus, the capacitance of the variable capacitance element can be defined only by setting the voltage dividing ratio of the resistance voltage dividing circuit, and the control voltage to be applied to the variable capacitance element can be configured with a simple circuit.

(4) The actuator is, for example, a piezoelectric actuator that displaces or deforms according to the inverse piezoelectric effect. With this configuration, a large displacement amount or a large deformation amount can be obtained at a relatively low voltage.

(5) The actuator is, for example, an electrostatic actuator that is displaced or deformed by an electrostatic force corresponding to an applied voltage. With this configuration, displacement or deformation in a minute space is facilitated.

(6) The actuator control circuit further includes a thermistor connected to the variable capacitance element. With this configuration, the temperature-capacitance characteristic of the variable capacitance element can be compensated by the temperature-resistance characteristic of the thermistor, and a stable displacement or deformation amount of the actuator can be obtained in a wide temperature environment. Further, when the actuator has temperature dependency, the characteristic of the displacement amount or the deformation amount with respect to the applied voltage to the actuator can be compensated by the characteristic of the temperature of the thermistor with respect to the resistance value, and a stable displacement amount or deformation amount of the actuator can be obtained in a wide temperature environment.

(7) The actuator control circuit further includes a temperature sensor that detects a temperature of the variable capacitance element, and the variable capacitance element control circuit corrects the control voltage applied to the variable capacitance element based on the temperature detection by the temperature sensor. With this configuration, the temperature dependence of the variable capacitance element can be reduced, and stable displacement or deformation of the actuator can be obtained in a wide temperature environment. In addition, when the actuator has temperature dependence, the temperature dependence can be reduced, and stable displacement or deformation of the actuator can be obtained in a wide temperature environment.

Effect of the utility model

According to the present invention, the actuator driving device can be obtained in which the capacitance is electrically determined by the control voltage, and the displacement amount or the deformation amount of the actuator can be specified at high speed.

Drawings

Fig. 1 is a block diagram showing a configuration of an actuator driving device 111 according to the first embodiment.

Fig. 2(a) and 2(B) are perspective views showing examples of the configuration of the actuator 11.

Fig. 3 is a diagram showing a relationship between a displacement amount of the actuator 11 with respect to an applied voltage.

Fig. 4 is a sectional view of a main portion of the variable capacitance module 21.

Fig. 5 is a diagram showing an example of the relationship between the control voltage and the capacitance value with respect to variable capacitance section 21C of variable capacitance module 21.

Fig. 6 is a circuit diagram of the entire inside of the variable capacitance module 21.

Fig. 7 is a diagram showing a relationship between a value (number of steps) of 5 bits based on the ports P21 to P25 shown in fig. 6 and a resistance-voltage-dividing ratio.

Fig. 8(a), 8(B), and 8(C) are circuit diagrams showing a connection structure of the variable capacitance element to the actuator according to the second embodiment.

Fig. 9 is a configuration example of a temperature compensation circuit in the actuator driving device according to the third embodiment.

Fig. 10(a) to 10(E) show examples of temperature compensation circuits other than the temperature compensation circuit shown in fig. 9.

Fig. 11(a) is a block diagram showing a configuration of an actuator driving device 114A according to the fourth embodiment. Fig. 11(B) is a block diagram showing a configuration of another actuator driving device 114B according to the fourth embodiment.

Fig. 12 is a block diagram showing a configuration of an actuator driving device 115 according to a fifth embodiment.

Fig. 13(a), 13(B), and 13(C) are front views of the actuator 12A according to the sixth embodiment.

Fig. 14(a), 14(B), and 14(C) are front views of other actuators 12B according to the sixth embodiment.

Fig. 15(a) is a perspective view of an actuator 13 according to the seventh embodiment, and fig. 15(B) is an equivalent circuit diagram thereof.

Fig. 16(a) and 16(B) are plan views of another actuator 14 according to the seventh embodiment.

Description of the reference numerals

AS … point of action; a BM … beam; C1-C6 … capacitive elements; c31, C32 … capacitors; a D22 … diode; e1, E2 … electrodes; EE … external connection electrode; FS … fixed point; FS1, FS2, FS3 … ferroelectric films; MP … movable piece; P11-P14 … ports; P21-P25 … ports; a PC1 … moisture-resistant protective film; PC2 … organic protective film; PF … piezoelectric film; PT1, PT2 … capacitor electrodes; r1, R2, R3 … resistive element; R11-R17 … resistance elements; R21-R25 … resistance elements; RE1, RE2 … resistive film patterns; rt … thermistor; a SI … substrate; SP … fasteners; SR1, SR2, SR3 … interlayer insulating films; SR4 … solder resist film; a SU … substrate; TI1, TI2 … wiring films; 11. 12A, 12B, 13, 14 … actuator; 21 … variable capacitance module; 21C … variable capacitance section (variable capacitance element); 21R … control voltage application circuit; 22 … variable capacitance diode; 30 … variable capacitance element control circuit; 40 … power supply circuit; a 50 … temperature sensor; 60 … bias voltage generating circuit; 110 … actuator control circuit; 111. 114A, 114B, 115 … actuator drive.

Detailed Description

Hereinafter, a plurality of embodiments for carrying out the present invention will be described by way of examples with reference to the accompanying drawings. The same reference numerals are attached to the same positions in the drawings. The embodiments are shown separately for convenience in consideration of ease of explanation or understanding of points, but substitutions or combinations of parts of the configurations shown in different embodiments are possible. In the second embodiment and the following second embodiment, the description of the same matters as in the first embodiment will be omitted, and only the differences will be described. In particular, the same operations and effects are not provided by the same components in each embodiment.

First embodiment

Fig. 1 is a block diagram showing a configuration of an actuator driving device 111 according to the first embodiment. The actuator driving device 111 is constituted by the actuator 11 and the actuator control circuit 110. The actuator control circuit 110 is a circuit that controls the applied voltage applied to the actuator 11.

The actuator control circuit 110 includes a variable capacitance section 21C, a variable capacitance element control circuit 30, and a power supply circuit 40. The variable capacitance section 21C corresponds to a "variable capacitance element" of the present invention.

The actuator 11 is displaced or deformed in accordance with the applied voltage. The variable capacitance section 21C determines the capacitance based on the control voltage. The variable capacitance element control circuit 30 applies a predetermined control voltage to the variable capacitance section 21C.

The variable capacitance section 21C is connected in series to the actuator 11. The actuator 11 and the variable capacitance section 21C constitute a capacitance voltage dividing circuit.

The power supply circuit 40 applies a predetermined voltage to a circuit including the actuator 11 and the variable capacitance section 21C.

The dc voltage output from the power supply circuit 40 is capacitively divided by the actuator 11 and the variable capacitance section 21C. Therefore, the voltage applied to the actuator 11 is a voltage that is capacitively divided by the actuator 11 and the variable capacitance section 21C.

Since the capacitance of the variable capacitance section 21C is determined based on the control voltage output from the variable capacitance element control circuit 30, the voltage applied to the actuator 11 can be controlled by the control voltage output from the variable capacitance element control circuit 30. Therefore, even if the voltage output from the power supply circuit 40 is constant, the voltage applied to the actuator 11 can be controlled by the control voltage. In addition, according to the usage method, even if the control voltage output from the variable capacitance element control circuit 30 is constant, the voltage applied to the actuator 11 changes according to the change in the voltage output from the power supply circuit 40.

Fig. 2(a) and 2(B) are perspective views showing examples of the configuration of the actuator 11. Fig. 2(a) and 2(B) each show a laminate of piezoelectric ceramic layers with electrode patterns formed thereon. The actuator shown in fig. 2a is a piezoelectric actuator utilizing the piezoelectric longitudinal effect, and expands and contracts (displaces) in the Z-axis direction by applying a voltage between two external electrodes. The actuator shown in fig. 2B is a piezoelectric actuator utilizing the piezoelectric lateral effect, and expands and contracts (displaces) in the X-axis direction by applying a voltage between two external electrodes.

Fig. 3 is a diagram showing a relationship between a displacement amount of the actuator 11 with respect to an applied voltage. Qualitatively, the displacement amount of the actuator 11 is proportional to the applied voltage. The proportionality coefficient is determined by factors such as a piezoelectric constant and a shape of the element.

Fig. 4 is a sectional view of a main portion of the variable capacitance module 21. In FIG. 4, the substrate SI has SiO formed on the surface₂A Si substrate of the film. On the substrate SI, a ferroelectric film FS1, a capacitor electrode PT1, a ferroelectric film FS2, a capacitor electrode PT2, and a ferroelectric film FS3 are alternately formed in this order to form a capacitor portion.

A moisture-resistant protective film PC1 is covered on the upper portion of the laminated film of the ferroelectric films FS1, FS2, and FS3 and the capacitor electrodes PT1 and PT 2. An organic protective film PC2 is further formed on the moisture-resistant protective film PC 1.

A wiring film TI1 is formed on the organic protective film PC 2. The wiring film TI1 is connected to predetermined positions of the capacitor electrodes PT1 and PT2 through contact holes. The wiring film TI1 is formed so as to cover the peripheries of the moisture-resistant protective film PC1 and the organic protective film PC 2.

An interlayer insulating film SR1 is formed on the surface of the wiring film TI 1. A resistive film pattern RE1 is formed on the surface of the interlayer insulating film SR 1. The surface of the resistive film pattern RE1 is covered with an interlayer insulating film SR2, and a resistive film pattern RE2 is formed on the surface of the interlayer insulating film SR 2. The surface of the resistive film pattern RE2 is covered with an interlayer insulating film SR 3.

The resistive film of the resistive film patterns RE1 and RE2 is formed by a thin film process (a process using photolithography and etching techniques) or a thick film process (a process using a printing technique such as screen printing). The resistance value of each resistive element is determined according to the width, length, and thickness of the resistive film pattern.

The resistive element 21B of the variable capacitance section is formed by the resistive film pattern RE 1. The resistive film pattern RE2 constitutes a control voltage application circuit 21R. The resistance element 21B and the control voltage applying circuit 21R of the variable capacitance section are shown later.

A wiring film TI2 is formed on the surface of the interlayer insulating film SR 3. The wiring film TI2 is connected to the wiring film TI1 via contact holes formed in the interlayer insulating films SR1, SR2, and SR 3.

The surface of the interlayer insulating film SR3 is covered with a solder resist film SR 4. An external connection electrode EE is formed on the opening of the solder resist film SR4 and on the surface of the wiring film TI 2.

The ferroelectric film FS1 is an insulating film for adhesion and diffusion prevention to the substrate SI and the moisture-resistant protective film PC 1. The ferroelectric film FS3 is an insulating film for adhesion to the moisture-resistant protective film PC 1. As the conductive material used for the capacitor electrodes PT1 and PT2, a high melting point noble metal material having good conductivity and excellent oxidation resistance can be used, and for example, PT or Au can be used.

As a thin film material used for the ferroelectric films FS1, FS2, and FS3, a dielectric material having a high dielectric constant can be used. Specifically, (Ba, Sr) TiO can be used₃(BST)、SrTiO₃、BaTiO₃、Pb(Zr，Ti)O₃Isoperovskite compound, SrBi₄Ti₄O₁₅And bismuth layer-structured compounds. By forming the variable capacitance element using these dielectric materials, when the displacement amount or the deformation amount of the actuator 11 is controlled, the variation width of the capacitance value can be obtained more largely, and the actuator 11 can be controlled more appropriately.

The wiring films TI1 and TI2 are formed of three layers of TI/Cu/TI, for example, with the TI layer formed to be 100nm and the Cu layer formed to be 1000nm, for example.

The external connection electrode EE is formed of two layers of Au/Ni, for example, the Ni layer of the first layer is formed to be 2000nm, for example, and the Au layer of the second layer is formed to be 200nm, for example.

The moisture-resistant protective film PC1 prevents moisture released from the organic protective film PC2 from entering the capacitor unit. As the moisture-resistant protective film PC1, SiNx or SiO can be used, for example₂、Al₂O₃、TiO₂And the like. In addition, the organic protective film PC2 absorbs mechanical stress from the outside. As the organic protective film PC2, PBO (polybenzoxazole) resin, polyimide resin, epoxy resin, or the like can be used.

The resistive material of the resistive film patterns RE1 and RE2 is, for example, Ni or Cr alloy.

In this way, since the ferroelectric capacitor is used as the variable capacitance element and the plurality of resistance patterns having different resistance values are used as the bias voltage applying circuit, the variable capacitance module 21 with the control voltage applying circuit can be configured to be small.

The present invention is not limited to the above embodiments. For example, the film thicknesses, the formation methods, the formation conditions, and the like of the respective layers shown in the above embodiments are merely examples, and can be arbitrarily changed within a range in which a desired function is not impaired as a thin film capacitor.

In the above-described embodiment, the case where the capacitor portion has a single-layer structure having one capacitance generating portion was described, but the present invention can be similarly applied to a case where the capacitor portion has a multi-layer structure having two or more capacitance generating portions.

Fig. 5 is a diagram showing an example of a relationship between a control voltage and a capacitance value with respect to the variable capacitance section 21C of the variable capacitance module 21. Since the ferroelectric film exhibits a dielectric constant that changes as the polarization amount changes according to the strength of an applied electric field, the capacitance value changes according to the change in the control voltage. Since the relationship between the control voltage and the capacitance is continuous in this way, the capacitance can be determined in a wide range by the control voltage.

Fig. 6 is a circuit diagram of the entire inside of the variable capacitance module 21. The variable capacitance module 21 includes a control voltage applying circuit 21R and a variable capacitance section 21C. The control voltage applying circuit 21R is a part of the variable capacitance element control circuit 30 shown in fig. 1. The variable capacitance section 21C determines the capacitance values between the ports P11 to P12 based on the voltages applied between the ports P13 to P14. The ports P21 to P25 of the control voltage applying circuit 21R are connected to I/O ports of an external control circuit. One ends of the resistor elements R21 to R25 are connected to the ports P21 to P25, and the other ends of the resistor elements R21 to R25 are connected in common to the port P13.

The external control circuit selectively sets the I/O port to a high level (power supply voltage) or a low level (ground voltage). Thus, the resistor elements R21 to R25 function as a resistor voltage divider circuit, and a control voltage corresponding to the voltage division ratio and the power supply voltage is applied to the port P13 of the variable capacitor portion 21C. Since the port P14 of the variable capacitance section 21C is grounded, the control voltage is applied between the ports P13 to P14 of the variable capacitance section 21C. The role of this partial pressure is detailed later.

In the variable capacitor section 21C, control voltages are applied to both ends of the capacitor elements C1 to C6 via the resistor elements R11 to R17. The resistance elements R11 to R17 correspond to the resistance element 21B shown in fig. 4. The resistance values of the resistance elements R11 to R17 are equal.

The capacitor elements C1 to C6 are ferroelectric capacitors in which ferroelectric films are sandwiched between opposing electrodes.

Fig. 7 is a diagram showing a relationship between a value (number of steps) of 5 bits and a resistance-voltage-dividing ratio based on the ports P21 to P25 shown in fig. 6. The lowest resistance value among the resistance values of the resistance elements R21 to R25 shown in fig. 6 is determined at a multiplication ratio of 2 as a reference. For example, the ratio of the resistance values of the resistance elements R21, R22, R23, R24, R25 is determined to be 1: 2: 4: 8: 16. for example, if R21 is 10k Ω, R22 is 20k Ω and R25 is 160k Ω.

For example, when the port P21 is at a high level and all of the ports P22 to P25 are at a low level, the resistor element R21 forms an upper arm of the resistance voltage divider circuit, and the parallel circuit of the resistor elements R22 to R25 forms a lower arm. For example, when the ports P21 and P22 are at a high level and the ports P23, P24, and P25 are at a low level, the parallel circuit of the resistance elements R21 and R22 forms the upper arm of the resistance voltage divider circuit, and the parallel circuit of the resistance elements R23 to R25 forms the lower arm. Further, since the lowest resistance value among the resistance values of the resistance elements R21 to R25 is determined at a ratio of 2 to 2, the above-described voltage division ratio can be set to 2 to the power of 5(═ 32) according to the combination of the high level and the low level of the ports P21 to P25.

The horizontal axis of fig. 7 indicates a 5-bit value based on the ports P21 to P25. The vertical axis represents a voltage ratio with respect to the power supply voltage.

According to the present embodiment, the capacitance of the variable capacitance section 21C can be determined at high speed by electric control, and therefore the actuator 11 can be driven at high speed. Further, since a circuit for directly controlling a power supply circuit that generates a relatively high voltage to be applied to the actuator 11 is not necessary, the entire aperture opening performance is simplified and the cost is reduced.

Second embodiment

In the second embodiment, a few examples of the connection structure of the variable capacitance element to the actuator are shown.

Fig. 8(a) shows an example in which the variable capacitance section 21C of the variable capacitance module is connected in series to the actuator 11. The circuit configuration is as shown in the first embodiment.

Fig. 8(B) shows an example in which a parallel connection circuit is formed by the actuator 11 and the variable capacitance section 21C, and a capacitor C31 is connected in series to the parallel connection circuit. According to this circuit configuration, the capacitance is divided by the capacitor C31 and the combined capacitance obtained by the parallel connection of the actuator 11 and the variable capacitance section 21C.

Fig. 8(C) shows an example in which a parallel connection circuit is formed by variable capacitance section 21C and capacitor C32, and actuator 11 is connected in series with this parallel connection circuit. According to this circuit configuration, the capacitance is divided by the combined capacitance of the variable capacitance section 21C and the capacitor C32 connected in parallel and the capacitance of the actuator 11.

In any of the circuit configurations shown in fig. 8(B) and 8(C), the range of change in the voltage applied to the actuator 11 with respect to the range of change in the capacitance of the variable capacitance section 21C can be narrowed, and the amount of displacement or the amount of deformation of the actuator 11 can be controlled with higher accuracy.

Third embodiment

The third embodiment shows an actuator driving device in which the temperature dependence of the variable capacitance element or the temperature dependence of the actuator is reduced.

Fig. 9 is a configuration example of a temperature compensation circuit in the actuator driving device according to the third embodiment. In fig. 9, the variable capacitance module 21 is configured as shown in the first embodiment. In the example shown in fig. 9, a thermistor Rt is inserted between the port P14 of the variable capacitance module 21 and the ground. Therefore, the bias voltage for the variable capacitance section 21C of the variable capacitance module 21 is determined by the resistance voltage division of the resistance elements R11 to R17 and the thermistor Rt.

The thermistor Rt is an example of the "temperature sensing element" in the present invention, and detects the temperature of the variable capacitance module including the variable capacitance section 21C or the temperature in the vicinity thereof. The capacitance of the variable capacitance section 21C of the variable capacitance module 21 has a positive temperature dependence with respect to temperature. On the other hand, the resistance value of the thermistor Rt has negative temperature dependence with respect to temperature. Therefore, as the temperature increases, the resistance value of the thermistor Rt decreases, and the control voltage applied to the variable capacitance section 21C increases, whereby the capacitance value of the variable capacitance section 21C decreases. This compensates the temperature of the variable capacitance section 21C.

Fig. 10(a) to 10(E) show examples of temperature compensation circuits other than the temperature compensation circuit shown in fig. 9. In the example of fig. 10(a), a resistance element R1 is connected in series to the thermistor Rt. In the example of fig. 10(B), the resistance element R2 is connected in parallel to the thermistor Rt. In the example of fig. 10(C), the thermistor Rt and the resistor element R2 form a parallel circuit, and the resistor element R1 is connected in series to the parallel circuit. In the example of fig. 10(D), the thermistor Rt and the resistor element R1 form a series circuit, and the resistor element R3 is connected in parallel to the series circuit. In the example of fig. 10(E), the thermistor Rt and the resistor element R2 form a parallel circuit, and the resistor element R1 is connected in series to the parallel circuit. The resistor element R3 is connected in parallel to a circuit including the thermistor Rt and the resistor elements R1 and R2. In this way, the dependence of the resistance value with respect to temperature can also be adjusted by the combination of the thermistor and the resistance element.

Since the voltage applied to the actuator is affected by the temperature dependence of the variable capacitance section 21C and the actuator itself also has temperature dependence, the temperature compensation may be determined such that the temperature dependence of the displacement amount or deformation amount of the actuator becomes small.

Fourth embodiment

The fourth embodiment shows an actuator driving device in which the temperature dependence of the variable capacitance element or the temperature dependence of the actuator is reduced.

In the example shown in fig. 11(a), a temperature sensor 50 is connected to the variable capacitance element control circuit 30. The temperature sensor 50 detects the temperature of the variable capacitance module including the variable capacitance section 21C or the temperature in the vicinity thereof. The variable capacitance element control circuit 30 corrects the control voltage to the variable capacitance section 21C based on the temperature detection result of the temperature sensor 50. This correction is a correction that ultimately reduces the temperature dependence of the displacement amount or deformation amount of the actuator.

In the example shown in fig. 11(B), the temperature sensor 50 is connected to the power supply circuit 40. The power supply circuit 40 corrects the voltage applied to the series circuit of the actuator 11 and the variable capacitance section 21C based on the temperature detection result of the temperature sensor 50. This correction is a correction that ultimately reduces the temperature dependence of the displacement amount or deformation amount of the actuator.

Fifth embodiment

In the fifth embodiment, an example in which a variable capacitance diode is used as a variable capacitance element is shown.

Fig. 12 is a block diagram showing a configuration of an actuator driving device 115 according to a fifth embodiment. The actuator driving device 115 is constituted by the actuator 11, the variable capacitance diode 22, the diode D22, and the bias voltage generating circuit 60.

The bias voltage generating circuit 60 applies a reverse bias voltage to the variable capacitance diode 22 via the diode D22. The diode D22 is a reverse flow prevention diode.

The actuator 11 and the variable capacitance diode 22 constitute a capacitance voltage dividing circuit, and the voltage applied to the actuator 11 is controlled by the capacitance of the variable capacitance diode 22.

As described above, even when a variable capacitance diode is used as the variable capacitance element, a capacitance voltage divider circuit with an actuator can be configured in combination with a fixed capacitance element as shown in fig. 8(a), 8(B), and 8 (C).

Sixth embodiment

In the sixth embodiment, an example of a type of actuator different from the actuator shown in the first embodiment is shown.

Fig. 13(a), 13(B), and 13(C) are front views of the actuator 12A according to the sixth embodiment. The actuator 12A forms a piezoelectric film PF on the base SU. The actuator 12A is fixed at its fixation point FS. The actuator 12A undergoes bending deformation, and the point of action AS is displaced.

The applied voltage in fig. 13(a) is 0V, and the polarities of the applied voltages are different in fig. 13(B) and 13 (C).

In this way, the operating point of the end of the actuator can be displaced in the vertical direction or in the direction along the arc according to the voltage applied to the actuator 12A.

Fig. 14(a), 14(B), and 14(C) are front views of other actuators 12B according to the sixth embodiment. The actuator 12B has a piezoelectric film PF formed on the base SU. The actuator 12B is fixed at its fixed point FS. The actuator 12B undergoes bending deformation, and the point of action AS is displaced.

The applied voltage in fig. 14(a) is 0V, and the polarities of the applied voltages are different in fig. 14(B) and 14 (C).

In this way, the central operating point of the actuator can be displaced in the vertical direction by the voltage applied to the actuator 12B.

The power supply circuit 40 shown in fig. 1 generates the positive and negative voltages described above. The amount of displacement in either the positive or negative direction can be increased or decreased by the control of the variable capacitance element control circuit 30.

Seventh embodiment

An example of an electrostatic actuator is shown in the seventh embodiment.

The actuator 13 is composed of an insulating stator SP, electrodes E1 and E2 formed on the stator, and a movable element MP. The movable element MP is a conductive body, and is separated from the electrodes E1 and E2 and supported by a support mechanism outside the figure.

As shown in fig. 15(B), electrostatic capacitances are formed between the mover MP and the electrodes E1, E2, respectively, and when a voltage is applied between the electrodes E1, E2, the mover MP is attracted by the electrostatic force. Then, the height of the movable element MP is determined by the voltage applied between the electrodes E1 and E2.

Fig. 16(a) and 16(B) are plan views of another actuator 14 according to the seventh embodiment. The actuator 14 is constituted by a fixed electrode E1, a beam BM, and an electrode E2 formed on the beam BM. The electrodes E1-E2 are comb-shaped into each other. When a voltage is applied between the electrodes E1 to E2, the beam BM is bent and deformed by an electrostatic force between the electrodes E1 to E2, and the point of action AS is displaced.

Other embodiments

In the above-described embodiments, the power supply circuit 40 has been described as outputting a constant voltage and controlling the capacitance of the variable capacitance section 21C by the control of the variable capacitance element control circuit 30, but the power supply circuit 40 may be a circuit that determines an output voltage based on a control signal given from the outside. In this case, the displacement amount or deformation amount of the actuator may be controlled in combination with the voltage generated by the control power supply circuit 40. For example, the control of the variable capacitance element control circuit 30 may be the primary control, and the control of the output voltage of the power supply circuit 40 may be the secondary control. Further, a component having a high fluctuation frequency of the actuator may be controlled by the variable capacitance element control circuit 30, and a component having a low fluctuation frequency may be controlled by the power supply circuit 40.

In the examples shown in fig. 13(a), 13(B), 13(C), 14(a), 14(B), and 14(C), the piezoelectric body is expanded and contracted to bend the entire body, but the actuator may be configured such that the deformable member is deformed by the expansion and contraction of the piezoelectric body. Further, the actuator may be configured to deform the deformable member into the barreled state by applying a compressive force to the deformable member.

Finally, the above description of the embodiments is not intended to be limiting in all respects. It is obvious to those skilled in the art that the modifications and variations can be made as appropriate. The scope of the present invention is not shown by the above embodiments, but by the scope of the present invention. The scope of the present invention includes modifications from the embodiments within the scope and range of equivalents.

Claims

1. An actuator driving device, characterized in that,

the actuator driving device includes an actuator that displaces or deforms in accordance with an applied voltage, and an actuator control circuit that controls the applied voltage to the actuator,

the actuator control circuit is constituted by: a variable capacitance element, a variable capacitance element control circuit, and a power supply circuit,

the variable capacitance element is connected to the actuator and determines an electrostatic capacitance according to a control voltage,

the variable capacitance element control circuit applies a control voltage to the variable capacitance element,

the power supply circuit applies a voltage to a circuit including the actuator and the variable capacitance element.

2. Actuator driving device according to claim 1,

the variable capacitance element includes at least two capacitor electrodes and a ferroelectric film formed between the two capacitor electrodes, and is a ferroelectric capacitor whose electrostatic capacitance is determined according to a control voltage value applied between the two capacitor electrodes.

3. Actuator driving device according to claim 2,

the variable capacitance element control circuit includes: the voltage divider circuit includes a resistance voltage divider circuit based on a plurality of resistance elements having different resistance values, and a voltage division ratio setting circuit that sets a voltage division ratio of the resistance voltage divider circuit.

4. Actuator drive arrangement according to one of the claims 1 to 3,

the actuator is a piezoelectric actuator that displaces or deforms according to the inverse piezoelectric effect.

5. Actuator drive arrangement according to one of the claims 1 to 3,

the actuator is an electrostatic actuator that is displaced or deformed by an electrostatic force corresponding to an applied voltage.

6. Actuator drive arrangement according to one of the claims 1 to 3,

the actuator control circuit further includes a thermistor connected to the variable capacitance element.

7. Actuator driving device according to claim 4,

8. Actuator driving device according to claim 5,

9. Actuator drive arrangement according to one of the claims 1 to 3,

the actuator control circuit further includes a temperature sensor that detects a temperature of the variable capacitance element, and the variable capacitance element control circuit corrects the control voltage applied to the variable capacitance element based on the temperature detection by the temperature sensor.

10. Actuator driving device according to claim 4,

11. Actuator driving device according to claim 5,