OSCILLATION DRIVE DEVICE, PHYSICAL QUANTITY MEASUREMENT DEVICE AND ELECTRONIC APPARATUS

• US 20100206074A1
• Filed: 02/12/2010
• Published: 08/19/2010
• Est. Priority Date: 02/19/2009
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: YOSHIDA, Naoki, KANAI, Masahiro
• Granted Patent: US 8,618,889 B2
• Time in Patent Office: Days
• US Class Current: 73/504.120
• CPC Class Codes: G01C 19/56 Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
• CPC Class Codes: H03B 5/06 Modifications of generator to ensure starting of oscillations
• CPC Class Codes: H03B 5/32 being a piezoelectric resonator selection of piezoelectric material H10N30/00
• CPC Class Codes: H03K 5/1515 non-overlapping
• CPC Class Codes: H03K 5/2481 with at least one differential stage

Abstract

There is provided an oscillation drive device that forms an oscillation loop with a vibrator for exciting a driving vibration on the vibrator. The oscillation drive device includes: a comparator that excites a driving vibration on the vibrator based on a signal in the oscillation loop with a given voltage as a reference; an oscillation detector that detects oscillation in the oscillation loop; a signal generation circuit that generates a switching control signal based on an oscillation result given by the oscillation detector; and a switch circuit inserted between the vibrator in the oscillation loop and an output of the comparator, wherein, during an oscillation startup stage in which oscillation in the oscillation loop is not detected by the oscillation detector, the switch circuit alternately switches, based on the switching control signal, between a period in which the output of the comparator and the vibrator are electrically connected and a period in which a predetermined set voltage is supplied to the vibrator.

Claims

1. An oscillation drive device that forms an oscillation loop with a vibrator for exciting a driving vibration on the vibrator, the oscillation drive device comprising:

a comparator that excites a driving vibration on the vibrator based on a signal in the oscillation loop with a given voltage as a reference;

an oscillation detector that detects oscillation in the oscillation loop;

a signal generation circuit that generates a switching control signal based on an oscillation result given by the oscillation detector; and

a switch circuit inserted between the vibrator in the oscillation loop and an output of the comparator,

wherein, during an oscillation startup stage in which oscillation in the oscillation loop is not detected by the oscillation detector, the switch circuit alternately switches, based on the switching control signal, between a period in which the output of the comparator and the vibrator are electrically connected and a period in which a predetermined set voltage is supplied to the vibrator.

2. An oscillation drive device according to claim 1, wherein the switch circuit electrically connects the output of the comparator with the vibrator based on the switching control signal in a stationary oscillation state in which oscillation in the oscillation loop is detected by the oscillation detector.

3. An oscillation drive device according to claim 1, wherein the set voltage is a voltage between a high potential side voltage of the comparator and a low potential side voltage of the comparator.

8. An oscillation drive device according to claim 1, wherein the comparator is a gain control amplifier that excites the oscillation amplitude in the oscillation loop to the driving vibration of the vibrator.

9. An oscillation drive device according to claim 1, wherein the signal generation circuit generates the switching control signal having a given frequency only during a predetermined period with the start timing of power-on reset of the oscillation drive device as a reference.

10. An oscillation drive device according to claim 1, wherein an end timing of the predetermined period is a timing at which the signal in the oscillation loop exceeds a predetermined threshold level is detected, or a predetermined count number is counted with the start timing of the predetermined period as a reference.

11. An oscillation drive device according to claim 1, wherein the signal generation circuit includes a power-on reset circuit that generates a power-on reset signal, and a pulse generation circuit that generates a pulse or a plurality of pulses based on the power-on reset signal in a predetermined period, wherein the pulse generation circuit includes a plurality of delay units wherein each of the delay units generates a pulse based on an input signal, and each of the delay units outputs a calculation result of logical addition of the generated pulse, wherein the signal with the given frequency is outputted during a period starting with a timing of a change in the power-on reset signal as a reference until a timing of a change in the detection result signal indicating that the signal in the oscillation loop exceeds the predetermined threshold level.

12. A physical quantity measurement device that measures a physical quantity corresponding to a detection signal that is outputted from a vibrator, based on a driving vibration excited by the vibrator and a physical quantity to be measured, the physical quantity measurement device comprising:

a vibrator;

the oscillation drive device recited in claim 1 for exciting a driving vibration on the vibrator; and

a detection device that detects an output signal corresponding to the physical quantity based on the detection signal,

wherein the detection device includes a synchronous wave detector that synchronously detects the detection signal based on an output of a synchronous wave detection comparator that generates a reference signal for synchronous wave detection based on a signal in the oscillation loop.

13. A physical quantity measurement device according to claim 12, wherein the detection device includes a phase shifter for adjusting phases of an output of the synchronous wave detection comparator and the detection signal.

14. An electronic apparatus comprising the physical quantity measurement device recited in claim 12.

4. An oscillation drive device that forms an oscillation loop with a vibrator for exciting a driving vibration in the vibrator, the oscillation drive device comprising:

a comparator that excites a driving vibration on the vibrator based on a signal in the oscillation loop with a given voltage as a reference;

a synchronous wave detection comparator that generates a reference signal for synchronous detection based on a signal in the oscillation loop;

an oscillation detector that detects oscillation in the oscillation loop;

a signal generation circuit that generates a switching control signal based on an oscillation result given by the oscillation detector;

a first switch circuit inserted between the vibrator in the oscillation loop and an output of the comparator; and

a second switch circuit inserted between an output of the synchronous wave detection comparator and the vibrator,

wherein, during an oscillation startup stage in which oscillation in the oscillation loop is not detected by the oscillation detector, the first switch circuit electrically shuts off the output of the comparator from the vibrator based on the switching control signal, and the second switch alternately switches based on the switching control signal between a period in which an output of the synchronous wave detection comparator and the vibrator are electrically connected and a period in which a predetermined set voltage is supplied to the vibrator.

5. An oscillation drive device according to claim 4, wherein, in the stationary oscillation state in which oscillation in the oscillation loop is detected by the oscillation detector, an output of the synchronous wave detection comparator is outputted as the reference signal based on the switching control signal, and the first switch circuit electrically connects the output of the comparator with the vibrator based on the switching control signal.

6. An oscillation drive device according to claim 4, wherein the polarity of the output of the comparator is the same as the polarity of the output of the synchronous wave detection comparator.

7. An oscillation drive device according to claim 4, wherein the set voltage is a voltage between a high potential side voltage of the synchronous wave detection comparator and a low potential side voltage of the synchronous wave detection comparator.