Analog drive circuit and drive control unit for piezoelectric element

Abstract

The present invention relates to an analog drive circuit and a drive control unit for a piezoelectric element. In one embodiment, an analog drive circuit (1) having an amplifier section (2) includes a power supply voltage input (VDD), a signal voltage input (DAC), a ground voltage input (-VDD, GND), a signal output (VCP), a first transistor (T1) and a second transistor (T2) connected to the power supply voltage input (VDD), a third transistor (T3) connected to the first transistor (T1) and having its base connected to the signal voltage input (DAC), a fourth transistor (T4) connected to the second transistor (T2) and connected to the signal output (VCP), a fifth transistor (T5) and a sixth transistor (T6) connected to the ground voltage input (-VDD, GND) and having their bases connected to the power supply voltage input (VDD), the sixth transistor (T6) being connected to the third transistor (T3) and the fourth transistor (T4), and the fifth transistor (T5) being further connected to the power supply voltage input (VDD) via a current limiting resistor (R6).

Description

[Technical Field]

[0001] An analog drive circuit for a piezoelectric element is described, as well as a control unit comprising such a drive circuit. [Background technology]

[0002] Documents US7271520B2, US5982304A, US2002 / 0084721A1, US2006 / 0028095A1, US2009 / 0146533A1, US2012 / 0013220A1, EP2600224A1, US8605053B2, EP2763317A2, US8854319B1, EP3018824A1, EP3065029A1, EP2472365B1 and US4994955A relate to drive circuits.

[0003] Documents US2019 / 0067552A1, US2019 / 0334077A1 and US2021 / 0141456A1 describe piezoelectric contact actuators. Summary of the Invention

[0004] The problem to be solved is to provide a drive circuit that is reliable and can be efficiently constructed.

[0005] This problem is solved inter alia by a drive circuit and a drive control unit with the features of the independent claims. Preferred developments are the subject of the dependent claims.

[0006] The analog drive circuit described herein is designed for generating, for example, piezoelectric elements, particularly haptic feedback effects.

[0007] In one embodiment, an analog drive circuit has an amplifier portion, the amplifier portion comprising: a power supply voltage input, an analog signal voltage input, a ground voltage input, an analog signal output, first and second transistors connected to the power supply voltage input and having their bases connected to each other, a third transistor connected to the first transistor and having its base connected to the signal voltage input, a fourth transistor connected to the second transistor and having its base connected to a feedback channel, the fourth transistor connected to the signal output, and fifth and sixth transistors connected to the ground voltage input and having their bases connected to the power supply voltage input, the sixth transistor further connected to the third and fourth transistors, the fifth transistor further connected to the power supply voltage input through a current limiting resistor, which may be located directly between the power supply voltage input and the emitter or collector of the fifth transistor.

[0008] The transistor is specifically a bipolar transistor, not a metal oxide semiconductor field effect transistor or MOSFET.

[0009] Because the power supply voltage line and the power supply voltage input in the drive circuit are at the same potential, these components will not be distinguished from each other and will be collectively referred to as the power supply voltage input below. The same applies to the signal voltage input, ground voltage input, signal output, and feedback channel.

[0010] The term "connected" refers in particular to the emitter or collector of the associated transistor. That is, for example, if a transistor is "connected" to another component, this means that there is an indirect or direct electrical connection between that component and the emitter or collector of the associated transistor, unless otherwise specified.

[0011] A feedback coupling channel or feedback channel refers, for example, to an inverting and / or non-inverting feedback.

[0012] The voltage of the power supply voltage input is higher than the voltage of the ground voltage input. For example, if +VDD is applied to the power supply voltage input, the voltage of the ground voltage input will be between -VDD and GND, or the ground voltage input will be -VV or GND. GND refers to the earth connection, specifically 0V.

[0013] Piezoelectric touch response, also known as piezo-haptic feedback, is playing an increasingly important role in human-machine interaction and can be found, for example, in industrial equipment, household appliances, and displays in the automotive sector, where information about the system's operation is conveyed to the user via short tactile impulses, such as vibrations.

[0014] To achieve market penetration of haptic applications, cost-effective, market-oriented, energy-efficient, environmentally friendly and manufacturable electronics are required.

[0015] One way to do this is to build a driver circuit from discrete electronic components, which are more readily available on the market than components based on application-specific integrated circuits, also known as ASICs. The driver circuit described here is an analog circuit made up of discrete components.

[0016] On the other hand, comparable circuits are usually based on specialized components for driving and controlling piezoelectric haptic applications, which are difficult to obtain on the market, often quite expensive, and some of which are not suitable for use in the automotive sector.

[0017] Another way to operate piezoelectric components is the H-bridge configuration described in US7271520B2, which describes only the H-bridge configuration, which is supplied with a PWM signal and buffered, and which only accepts positive voltages.

[0018] However, the drive circuit described here also allows for operation with bipolar drive voltages, thereby improving the piezoelectric performance of the system: it utilizes not only the expansion of the piezoelectric element under positive voltage, but also its contraction under negative voltage, significantly increasing the total displacement.

[0019] Furthermore, the embodiment shown in US Pat. No. 7,271,520 B2 has the drawback that, due to the single-stage H-bridge configuration, only piezoelectric elements with relatively small capacitance can be used, or the transistors used must be designed as power transistors, which leads to increased costs and space.

[0020] Document US5982304A describes a solution using two driver ICs connected in series. The proposed embodiment is less costly as it does not use a special driver IC, where IC stands for integrated circuit.

[0021] Document US2002 / 0084721A1 shows an alternative embodiment that differs significantly from the push-pull configuration described here.

[0022] In document US2006 / 0028095A1, signal amplification is achieved using an operational amplifier IC and a comparator IC. The drive circuit described therein does not use an operational amplifier IC or a comparator IC.

[0023] In document US2009 / 0146533A1, two operational amplifier ICs are used to transmit signals to both contacts of the piezoelectric element, and the described embodiment limits the drive voltage to +40 V. In contrast, the drive circuit described here does not use operational amplifier ICs and has no limitations on signal levels.

[0024] Document US2012 / 0013220A1 presents a design for converting PWM signals to analog signals. This design uses a series of operational amplifiers. However, the driver circuit described there uses analog input signals, specifically PWM signals between 0V and 3.3V, and does not use operational amplifiers. Furthermore, concepts based on PWM signals are susceptible to harmonics (Obertoene), which can cause noise in piezoelectric components. PWM stands for pulse width modulation.

[0025] Document EP 2600224 A1 describes a technical embodiment for sensing in haptic feedback applications, while the drive circuit described therein is not concerned with the sensing function but rather only with the generation of control signals in particular for the displacement of piezoelectric elements.

[0026] Document US8605053B2 describes a drive circuit in the form of a full-bridge configuration for supplying a drive signal for haptic feedback to a piezoelectric component, whereas the drive circuit described therein differs from this in that it uses a half-bridge configuration and / or a push-pull configuration.

[0027] Although the document EP2763317A2 discusses the system configuration, the document does not mention the design of the amplifier circuitry or the wiring of the piezoelectric haptic components with the drive signals.

[0028] Document US8854319B1 proposes a boost converter with a transformer, whereas the drive circuit described therein does not require a transformer.

[0029] Documents EP 3018824 A1, EP 3065029 A1 and EP 2472365 B1 relate to piezoelectric sensors, whereas the circuit presented therein serves as a drive solution.

[0030] Document US4994955A discusses a solution in which a special driver IC uses multiple MOSFETs and inductors. The driver circuit described therein does not use a driver IC, MOSFETs, or inductors.

[0031] The driver circuit described here may comprise, for example, two sections: an amplifier section and a half-bridge circuit for transmitting a signal to the piezoelectric element, the signal level being, for example, about 120V.

[0032] As active elements, preferably only npn and pnp transistors approved for the automotive sector are used.

[0033] The first part of the circuit, the amplifier part, ensures that the input signal is sufficiently amplified. For this purpose, a series of npn and pnp transistors are combined in such a way that the dispersion of the electrical characteristics of the active components does not substantially affect the generated signal. This allows the use of many transistors available on the market, making the selection of cost-effective components much easier. Furthermore, the space requirements on the printed circuit board are comparable to solutions based on ASIC components. However, the latter are significantly more expensive than the discrete components used in the proposed solution.

[0034] Furthermore, the proposed solution offers a much better signal quality than known solutions using ASICs, although when using ASIC components the signal usually contains harmonics, which introduce additional unwanted noise into the piezoelectric components, which is very detrimental for haptic feedback applications.

[0035] The second part of the driver circuit can be configured as a switch, for example, in a push-pull half-bridge configuration, where an npn transistor and a pnp transistor in the push-pull configuration are regulated via an ohmic voltage divider. The second ohmic voltage divider acts as a feedback connection to the amplifier part of the circuit, so the maximum achievable voltage can be set by the second ohmic voltage divider.

[0036] Therefore, the drive circuit described here does not require a transformer, MOSFETs, or driver ICs. Furthermore, the signal quality of the proposed solution is clearly better than prior art solutions, and it is also less expensive.

[0037] According to at least one embodiment, the drive circuit further comprises a further circuit portion, preferably connected after the amplifier portion.

[0038] According to at least one embodiment, the further circuit portion comprises a seventh transistor having a base connected to the second and / or fourth transistor, for example connected to the power supply voltage input.

[0039] According to at least one embodiment, the further circuit portion comprises an eighth transistor having a base connected to the second and / or fourth transistor, for example connected to the ground voltage input.

[0040] According to at least one embodiment, the seventh and eighth transistors are connected to a signal output, and one or more resistors may be disposed between the seventh and eighth transistors and the signal output.

[0041] According to at least one embodiment, the bases of the seventh and eighth transistors are connected to the fourth transistor via electrical resistances, which means that only the corresponding electrical resistances are connected between, for example, the associated collector or emitter of the fourth transistor and the bases of the seventh and eighth transistors.

[0042] According to at least one embodiment, the seventh transistor is an npn transistor and the eighth transistor is a pnp transistor.

[0043] According to at least one embodiment, the drive circuit further comprises one or more circuit extensions. At least one circuit extension is configured similarly to the further circuit parts. This means, for example, that the at least one circuit extension and the further circuit parts have the same circuit configuration, in particular the same number and connections of transistors and resistors. The at least one circuit extension and the further circuit parts may differ from each other in the type of transistors and / or electrical resistors used. If there are multiple circuit extensions, all circuit extensions may have the same structure, or circuit extensions of different structures may be combined.

[0044] According to at least one embodiment, the at least one circuit extension and the further circuit part are connected to the fourth transistor and the signal output, respectively. The at least one circuit extension and the further circuit part may have the same electrical connection points to the amplifier part and / or the signal output.

[0045] According to at least one embodiment, the feedback channel is connected to the signal output and / or the ground voltage input via an electrical resistor, respectively, and can include an electrical trace that electrically extends from between the two resistors directly to the base of the fourth transistor.

[0046] According to at least one embodiment, the first transistor and / or the second transistor are each connected to the power supply voltage input via further electrical resistors, which may be of the same magnitude or may be different from each other.

[0047] According to at least one embodiment, the fifth and sixth transistors are directly connected to the ground voltage input, or alternatively, there may be an electrical resistor between them.

[0048] According to at least one embodiment, the base of the first transistor and / or the second transistor is connected to the emitter or collector of the third transistor via an additional electrical resistance, which may be higher than the resistance between the first and second transistors and the power supply voltage input.

[0049] According to at least one embodiment, the amplifier part and / or the further circuit part and / or at least one circuit extension part, or the entire drive circuit, does not include some or all of the following: transformers, field effect transistors, inductors, digital integrated circuits such as ASICs, etc. That is, at least one relevant part of the driver circuit may consist of bipolar transistors and electrical resistors.

[0050] According to at least one embodiment, the first transistor and / or the second transistor are pnp transistors. Alternatively or additionally, the third transistor, the fourth transistor, the fifth transistor and / or the sixth transistor are npn transistors.

[0051] According to at least one embodiment, the power supply voltage input is set to a voltage between 40 V and 250 V. For example, the voltage is at least 80 V or at least 100 V, and / or the voltage is a maximum of 200 V or a maximum of 140 V.

[0052] According to at least one embodiment, the signal voltage input is set to a voltage of at least −10 V to 10 V. For example, to drive and control the piezoelectric element in the signal output, the voltage of the signal voltage input varies as desired between 0 V to 3.3 V, 0 V to 5 V, −5 V to +5 V, or −3 V to +3 V.

[0053] According to at least one embodiment, the signal output is set to a value, in particular the capacitance of the piezoelectric element, e.g., with respect to the earth connection, of at least 0.1 μF and at most 0.1 mF, e.g., at least 0.5 μF and / or at most 10 μF or at most 5 μF.

[0054] Additionally, a drive control unit is described, which includes one or more of the drive circuits described in connection with one or more of the embodiments above, and therefore features of the drive circuits are also disclosed for the drive control unit, and vice versa.

[0055] In one embodiment, the drive control unit comprises: a digital-to-analog control circuit; a buffer circuit connected directly or indirectly after the digital-to-analog control circuit, e.g., for impedance matching and / or preamplification; a drive circuit connected directly or indirectly after the buffer circuit; and one or more piezoelectric contact actuators connected directly or indirectly after the driver circuit.

[0056] The drive circuit and drive control unit described herein will be described in detail below by way of example with reference to the drawings, in which the same reference numerals refer to the same elements in the various drawings, although the drawings are not to scale and individual elements may be exaggerated for ease of understanding. [Brief explanation of the drawings]

[0057] [Figure 1] FIG. 1 shows a schematic block diagram of an embodiment of a drive control unit having a drive circuit as described herein. [Figure 2] 2 and 3 show schematic block diagrams of embodiments of the drive circuits described herein. DETAILED DESCRIPTION OF THE INVENTION

[0058] 1 shows an embodiment of a drive unit 10. The control unit 10 comprises a digital-to-analog control circuit 11 followed by a buffer circuit 12 for impedance matching and / or preamplification, followed by a drive circuit 1 and followed by at least one piezoelectric contact actuator 14.

[0059] In one embodiment, an analog signal, for example a signal with a voltage between 0V and 3.3V or between 0V and 5V, is provided from the DAC output of the digital-to-analog control circuit 11. The digital-to-analog control circuit 11 is, for example, a microcontroller such as an MCU DAC or a function generator. The digital-to-analog control circuit 11 therefore provides the input signal for the drive circuit 1.

[0060] This signal from the digital-to-analog control circuit 11 can optionally be pre-amplified, for example from 0-3 V to 0-5 V, via a buffer circuit 12, e.g., MCP6421T or TLV379IDBVT. Additionally or alternatively, the buffer circuit 12 can serve to match the impedance of this signal. However, it is also possible to omit the buffer circuit 12 and have the driver circuit 1 receive the input signal directly from the digital-to-analog control circuit 11.

[0061] In the drive circuit 1, the signal is amplified and transmitted to the piezoelectric contact element 14 via, for example, an H-bridge circuit.

[0062] Such a drive control unit 10 with integrated drive circuitry 1 can be used to provide haptic feedback, for example, on a screen, a switch element and / or a steering wheel, to improve the user experience. Furthermore, a sensor circuit can be integrated into the overall system 10, not shown, whereby, for example, actuation of a switch element triggers a signal from a piezoelectric haptic element 14, which is detected and evaluated by the controller.

[0063] 2 is a schematic diagram of an example of a drive circuit 1. The drive circuit 1 has a power supply voltage input VDD, for example, 120 V, an analog signal voltage input DAC, for example, 0 to 5 V, a ground voltage input, for example, −VDD or GND, and an analog signal output VCP. The signal output VCP is connected to a piezoelectric contact element 14 that is not part of the drive circuit 1 and is represented by a capacitance Cp.

[0064] The first amplifier section 2 of the driver circuit 1 comprises a number of bipolar transistors T1 to T6, designed as pnp or npn transistors (see the circuit symbol in Figure 1). Furthermore, a number of electrical resistors R3 to R7 are provided. The emitters of transistors T1 and T2 are connected to the power supply voltage input VDD via resistors R3 and R4, while the emitters of transistors T5 and T6 are directly connected to the ground voltage input -VDD. Furthermore, the bases of transistors T5 and T6 are connected to the power supply voltage input VDD via a current-limiting resistor R6, as is the collector of transistor T5. The current-limiting resistor R6 limits the maximum current flowing through the circuit. For example, the maximum current may be less than 2 A or 1 A.

[0065] The base of transistor T3 is directly connected to the signal voltage input DAC. The emitter of transistor T3 is connected to the collector of transistor T6 and also to the emitter of transistor T4. The collectors of transistors T3 and T4 are connected to the collectors of transistors T1 and T2. The collector of transistor T3 is also connected to the bases of transistors T1 and T2 via resistor R5.

[0066] The base of transistor T4 is connected to a feedback channel F. The feedback channel F branches between two resistors R1 and R2, which are connected in series and in parallel with a capacitor Cp, which is connected to GND.

[0067] The driver circuit 1 further comprises a circuit section 3, which forms an additional amplifier stage after the first amplifier section 2. Circuit section 3 comprises transistors T7 and T8, the bases of which are connected to the collectors of transistors T2 and T4 via a resistor R7. The collectors of transistors T7 and T8 are connected directly to the power supply voltage input VDD or to the ground voltage input −VDD. The emitters of transistors T7 and T8 are connected to each other via resistors R8 and R9 connected in series. A signal output VCP is tapped between resistors R8 and R9 and directed to a capacitor Cp via a subsequent resistor R10.

[0068] Therefore, as described above, the driver circuit 1 is supplied with an analog input signal DAC, a power supply voltage +VDD, for example 120V, and a ground voltage −VDD.

[0069] As shown in Figure 2, amplifier section 2, which includes transistors T1-T6, is differentially coupled between the DAC and GND. Transistors T3 and T4 are the non-inverting and inverting amplifier sections. Load transistors T1 and T2 form an active current mirror, converting a small differential input signal between the DAC and GND into a so-called single-ended amplified output signal VCP.

[0070] Transistors T5 and T6 are controlled by the power supply voltages +VDD and -VDD to sink a specific current value based on their respective base-emitter voltages. Transistors T7 and T8 form the second stage of output amplification. The output of transistor T4 is amplified by transistor T7, a configuration also known as a common-emitter configuration.

[0071] Two resistors R8 and R9 stabilize the transistors T7 and T8, ensuring the stability of the output signal VCP. The piezoelectric contact load Cp is supplied with the output signal VCP via a resistor R10. Resistors R1 and R2 feed a feedback signal back to the inverting part of amplifier 2, which is therefore coupled in a so-called follower configuration.

[0072] The piezoelectric tactile actuator 14 may be configured, for example, as described in US 2019 / 0067552 A1, US 2019 / 0334077 A1, or US 2021 / 0141456 A1, the disclosures of which relating to the piezoelectric tactile actuator 14 are incorporated by reference.

[0073] It should be noted that the explanation regarding FIG. 1 also applies to FIG. 2, and vice versa.

[0074] The drive circuit 1 illustrated in Figure 2 can be expanded as shown in Figure 3. This is particularly useful when operating larger haptic loads Cp.

[0075] Thus, there may be multiple circuit extensions 4 or only one circuit extension 4. Three circuit extensions 4 are provided according to Fig. 3, all of which are connected to the first tap point A and the second tap point B together with the further circuit portion 3. The further circuit portion 3 and the circuit extensions 4 may be of the same structure. In other words, four further circuit portions 3 may be provided, provided that the transistors T7, T8 and T9, T10 are the same, and the resistors R8, R9 and R11, R12 are the same.

[0076] Using the components in the table below and the circuit shown in Figures 2 and 3, an embodiment provides a piezoelectric load Cp of 1 µF to 3.6 µF, in particular Cp = 3.6 µF.

[0077] [Table 1]

[0078] The current can be adjusted via resistor R6, as the value of resistor R6 essentially determines the current.

[0079] The values ​​of resistors R1 to R5 and R7 to R11 may vary, for example, by up to 30%, up to 10%, up to 3% from the values ​​listed in the table.

[0080] In the example of driver circuit 1, the resistance ratios of R1 / R2 and / or R8 / R9 and / or R11 / R12 shown in the table above can be maintained individually or in combination with a tolerance of up to 30%, up to 10% or up to 3%.

[0081] It should be noted that the explanations regarding FIGS. 1 and 2 also apply to FIG. 3, and vice versa.

[0082] The components shown are preferably arranged in the order shown, in particular directly one above the other, unless otherwise specified. Components that are not touching in the drawings are preferably spaced apart from one another. Where lines are drawn parallel to one another, corresponding areas are preferably also parallel to one another. Furthermore, unless otherwise specified, the relative positions of the components shown are accurately reproduced.

[0083] The invention described herein is not limited by the illustrative examples, but rather includes each and every novel feature and each and every combination of features, and in particular includes each and every combination of features in the claims, even if that feature or combination itself is not explicitly recited in the claims or embodiments.

[0084] This application claims priority from German patent application 102023104733.7, the disclosure of which is incorporated by reference. [Explanation of symbols]

[0085] 1 Drive circuit 2 Amplification section (Verstaerkungsteil) 3 Other circuit parts 4 Circuit extension (Schaltungserweiterung) 10 Drive control unit 11 Digital-analog control circuit 12 Buffer circuit 14 Piezo-haptischer Aktuator A First Tap Point B 2nd tap point (zweiter Abgriffpunkt) Cp Piezoelectric capacitance F Feedback-coupled channel, feedback channel (Rueckkopplungskanal, Feedback-Kanal) T Bipolar Transistor R Electrical resistance GND Earth, ground voltage input (Erdanschluss, Grundspannungseingang) VAC Analog signal voltage input VCP Analog signal output VDD Power supply voltage input (Versorgungspannungseingang)

Claims

1. An analog drive circuit (1) having an amplifier section (2), The amplification portion (2) is A power supply voltage input (VDD), an analog signal voltage input (DAC), a ground voltage input (-VDD, GND), and an analog signal output (VCP). a first transistor (T1) and a second transistor (T2) connected to the power supply voltage input (VDD) and having bases connected to each other; a third transistor (T3) connected to the first transistor (T1) and having a base connected to the signal voltage input (DAC); a fourth transistor (T4) connected to the second transistor (T2) and having a base connected to a feedback channel (F), the fourth transistor (T4) being connected to the signal output (VCP); a fifth transistor (T5) and a sixth transistor (T6) connected to the ground voltage input (-VDD, GND) and having their bases connected to the power supply voltage input (VDD), the sixth transistor (T6) further connected to the third transistor (T3) and the fourth transistor (T4), and the fifth transistor (T5) further connected to the power supply voltage input (VDD) via a current limiting resistor (R6).

2. The amplifier further includes a further circuit section (3) connected to a stage subsequent to the amplifier section (2), the further circuit section (3) comprising: a seventh transistor (T7) connected to the power supply voltage input (VDD) and having a base connected to the second transistor (T2) and the fourth transistor (T4); an eighth transistor (T8) connected to the ground voltage input (-VDD, GND) and having a base connected to the second transistor (T2) and the fourth transistor (T4); 2. A drive circuit (1) according to claim 1, wherein the seventh transistor (T7) and the eighth transistor (T8) are connected to the signal output (VCP).

3. The bases of the seventh transistor (T7) and the eighth transistor (T8) are connected to the fourth transistor (T4) via an electrical resistor (R7); 3. A drive circuit (1) according to claim 2, wherein said seventh transistor (T7) is an npn transistor and said eighth transistor (T8) is a pnp transistor.

4. Further comprising at least one circuit extension (4), 4. The drive circuit (1) according to claim 2 or 3, wherein the circuit extension (4) is configured similarly to the further circuit part (3), and the at least one circuit extension (4) and the further circuit part (3) are connected to the fourth transistor (T4) and the signal output (VCP), respectively.

5. 5. The drive circuit (1) according to any one of claims 1 to 4, wherein the feedback channel (F) is connected to the signal output (VCP) and to a ground connection (GND) via respective electrical resistors (R1, R2).

6. the first transistor (T1) and the second transistor (T2) are each connected to the power supply voltage input (VDD) via further electrical resistors (R3, R4); The drive circuit (1) according to any one of claims 1 to 5, wherein the fifth transistor (T5) and the sixth transistor (T6) are directly connected to the ground voltage input (-VDD, GND).

7. 7. The drive circuit (1) according to claim 1, wherein the bases of the first transistor (T1) and the second transistor (T2) are connected to the third transistor (T3) via an additional electrical resistor (R5).

8. 8. The drive circuit (1) according to any one of the preceding claims, wherein at least the amplifier part (2) is free of transformers, field effect transistors, inductors and digital integrated circuits.

9. the first transistor (T1) and the second transistor (T2) are each pnp transistors, and the third transistor (T3), the fourth transistor (T4), the fifth transistor (T5), and the sixth transistor (T6) are each npn transistors; the power supply voltage input (VDD) is set to a voltage of 40 V or more and 250 V or less, and the signal voltage input (DAC) is set to at least one voltage of −10 V or more and 10 V or less; 9. The drive circuit (1) according to claim 1, wherein the capacitance (Cp) of the signal output (VCP) to the earth (GND) is set to be equal to or greater than 0.1 μF and equal to or less than 0.1 mF.

10. A drive control unit (10), A digital-analog control circuit (11); a buffer circuit (12) connected after the digital-analog control circuit (11) for impedance matching and / or preamplification; a drive circuit (1) according to any one of claims 1 to 9, connected to a stage subsequent to the buffer circuit (12); A drive control unit (10) comprising a piezoelectric tactile actuator (14) connected to the rear stage of the drive circuit (1).

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