DRIVE CIRCUIT AND PHYSICAL QUANTITY MEASURING DEVICE

• US 20120055254A1
• Filed: 08/31/2011
• Published: 03/08/2012
• Est. Priority Date: 09/02/2010
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: YAMAGUCHI, Masayuki
• Granted Patent: US 8,487,509 B2
• Time in Patent Office: Days
• US Class Current: 73/649
• CPC Class Codes: B06B 1/0207 Driving circuits specially adapted for particular applications, see the relevant subclass, e.g. G01; circuits for steering transducer arrays G10K11/34; basic circuits H03
• CPC Class Codes: G01C 19/5776 Signal processing not specific to any of the devices covered by groups G01C19/5607 - G01C19/5719
• CPC Class Codes: G01D 3/036 on measuring arrangements themselves
• CPC Class Codes: H02P 31/00 Arrangements for regulating or controlling electric motors not provided for in groups H02P1/00 - H02P5/00, H02P7/00 or H02P21/00 - H02P29/00
• CPC Class Codes: H10N 30/802 Circuitry or processes for operating piezoelectric or electrostrictive devices not otherwise provided for, e.g. drive circuits

Abstract

In order for keeping the amplitude of the excitation current of a vibrator constant irrespective not only of the temperature variation but also of the manufacturing variation and the variation in frequency, a comparison control circuit for controlling the amplitude of the drive signal for exciting the vibrator includes a comparative voltage supply circuit for supplying the comparative voltage, and the comparative voltage supply circuit generates the comparative voltage with a constant current source and a second resistor made of a material the same as a material of a first resistor included in a current-voltage conversion circuit.

Claims

1. A drive circuit adapted to output a drive signal for exciting a vibrator, comprising:

a current-voltage conversion circuit adapted to convert an excitation current input into a voltage;

a full-wave rectifying circuit adapted to perform full-wave rectification on an output voltage from the current-voltage conversion circuit;

a drive signal generation circuit adapted to generate the drive signal based on the output voltage from the current-voltage conversion circuit; and

a comparison control circuit adapted to compare an output voltage from the full-wave rectification circuit with a comparative voltage to thereby control an amplitude of the drive signal,

wherein the comparison control circuit includes a comparative voltage supply circuit adapted to supply the comparative voltage, and

the comparative voltage supply circuit generates the comparative voltage with a constant current source and a second resistor made of a material the same as a material of a first resistor included in the current-voltage conversion circuit.

2. The drive circuit according to claim 1, wherein

the first resistor and the second resistor are disposed in the same resistor area in an array fashion.

3. The drive circuit according to claim 1, wherein

the first resistor and the second resistor are each composed of one of a resistor cell and a combination of a plurality of resistor cells, the resistor cells each having the same resistance value.

4. The drive circuit according to claim 1, wherein

the resistance value of the first resistor and the resistance value of the second resistor are determined based on a result of calculation of comparing an amplitude of the excitation current and a limit value with which a breakage current causing breakage of the vibrator flows.

5. The drive circuit according to claim 1, wherein

the current-voltage conversion circuit and the comparison control circuit are connected to a common ground potential.

6. A physical quantity measuring device comprising the drive circuit according to claim 1.

7. A physical quantity measuring device comprising the drive circuit according to claim 2.

8. A physical quantity measuring device comprising the drive circuit according to claim 3.

9. A physical quantity measuring device comprising the drive circuit according to claim 4.

10. A physical quantity measuring device comprising the drive circuit according to claim 5.