# US 8,786,162 B2 · Device for driving a piezoelectric element

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- Number: US 8,786,162 B2
- Document ID: US8786162B2
- Status: Granted
- Kind: B2
- Application number: 13/398,838
- Filed: 2012-02-17
- Published: 2012-08-23
- Granted: 2014-07-22
- Earliest claimed: 2011-02-21
- Assignees: Renesas Electronics Corporation
- Applicants: Shingo Tajima; Shoji Tsuchioka; Takehiko Umeyama
- Inventors: Shingo Tajima; Shoji Tsuchioka; Takehiko Umeyama
- Web page: https://patentgrep.com/patent/US8786162B2

## CPC

- H10N 30/802: {Circuitry or processes for operating piezoelectric or electrostrictive devices not otherwise provided for, e.g. drive circuits}
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR

## Abstract

The disclosed invention provides a device for driving a piezoelectric element, making it possible to make an output voltage follow a control voltage during a discharging action. A charging circuit charges a piezo element through a first node. A discharging circuit discharges electric charge charged in the piezo element through the first node. A control circuit makes switching to cause the discharging circuit to perform a discharging action or cause the charging circuit to perform a charging action, based on a comparison between the magnitude of a voltage being applied to the piezo element and the magnitude of a control voltage.

## Claims

### Claim 1

A device for driving a piezoelectric element, comprising:
a charging circuit that charges the piezoelectric element through a first node;
a discharging circuit that discharges electric charge charged in the piezoelectric element through the first node; and
a control circuit that controls switching to cause the discharging circuit to perform a discharging action or cause the charging circuit to perform a charging action, based on a comparison between the magnitude of a voltage being applied to the piezoelectric element and the magnitude of a control voltage,
wherein the discharging circuit includes:
a current output amplifier;
a first switch that is provided between the first node and a ground and controlled by the output of the current output amplifier; and
a second switch that is provided between the output of the current output amplifier and a ground, and
wherein the control circuit controls an input voltage to the current output amplifier and controls ON/OFF of the second switch.

### Claim 2 (depends on 1)

The device for driving a piezoelectric element according to claim 1, further comprising an H bridge circuit provided between the first node and a low potential power supply,
wherein the piezoelectric element is coupled between a first output node of the H bridge circuit and a second output node of the H bridge circuit.

### Claim 3 (depends on 2)

The device for driving a piezoelectric element according to claim 2,
wherein the control circuit includes a voltage detecting circuit that detects an output voltage corresponding to a difference between a voltage at the first output node of the H bridge circuit and a voltage at the second output node of the H bridge circuit.

### Claim 4 (depends on 3)

The device for driving a piezoelectric element according to claim 3,
wherein the control circuit includes an error amplifier that outputs a voltage depending on an error between the output voltage detected by the voltage detecting circuit and the control voltage.

### Claim 5 (depends on 1)

The device for driving a piezoelectric element according to claim 1, wherein the charging circuit is a voltage up circuit that outputs a voltage more than or equal to an input voltage.

### Claim 6 (depends on 1)

The device for driving a piezoelectric element according to claim 1, wherein the charging circuit is a voltage up/down converter that outputs a voltage more than or equal to an input voltage in a voltage up mode and outputs a voltage less than the input voltage in a voltage down mode.