CONSTANT-TEMPERATURE PIEZOELECTRIC OSCILLATOR AND METHOD OF MANUFACTURING THE SAME

• US 20140070892A1
• Filed: 04/05/2013
• Published: 03/13/2014
• Est. Priority Date: 03/24/2010
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: MATSUOKA, Jun, SOGA, Tadayoshi, OGINO, Akitoshi, OINUMA, Yuichi
• Granted Patent: US 9,007,134 B2
• Time in Patent Office: Days
• US Class Current: 331/34
• CPC Class Codes: H03B 5/04 Modifications of generator to compensate for variations in physical values, e.g. power supply, load, temperature
• CPC Class Codes: H03B 5/32 being a piezoelectric resonator selection of piezoelectric material H10N30/00
• CPC Class Codes: H03L 1/022 by indirect stabilisation, i.e. by generating an electrical correction signal which is a function of the temperature H03L1/021 takes precedence
• CPC Class Codes: H03L 1/023 by using voltage variable capacitance diodes
• CPC Class Codes: H03L 1/04 Constructional details for maintaining temperature constant
• CPC Class Codes: Y10T 29/42 Piezoelectric device making

Abstract

A constant-temperature piezoelectric oscillator includes: a piezoelectric vibrator; an oscillation circuit; a frequency voltage control circuit; a temperature control section; and an arithmetic circuit, wherein the temperature control section includes a temperature-sensitive element, a heating element, and a temperature control circuit, the frequency voltage control circuit includes a voltage-controlled capacitance circuit capable of varying the capacitance value in accordance with the voltage, and a compensation voltage generation circuit, and the arithmetic circuit makes the compensation voltage generation circuit generate a voltage for compensating a frequency deviation due to a temperature difference between zero temperature coefficient temperature Tp of the piezoelectric vibrator and setting temperature Tov of the temperature control section based on a frequency-temperature characteristic compensation amount approximate formula adapted to compensate the frequency deviation, and then applies the voltage to the voltage-controlled capacitance circuit to compensate the frequency.

Claims

1. A constant-temperature oscillator, comprising:

a vibrator that has a zero temperature coefficient as a frequency-temperature characteristic;

an oscillation circuit that excites the vibrator;

a voltage-controlled capacitance circuit that configures a resonant circuit with the vibrator;

a temperature controller that controls a temperature of the vibrator so as to adjust the temperature to a predetermined temperature; and

a compensation voltage generation circuit that outputs a compensation voltage to the voltage-controlled capacitance circuit, wherein

the compensation voltage compensates an oscillating frequency deviation between a first oscillating frequency of the oscillation circuit when the vibrator is at a zero temperature coefficient temperature and a second oscillating frequency of the oscillation circuit when the vibrator is at the predetermined temperature.

2. The constant-temperature oscillator according to claim 1, further comprising:

an arithmetic circuit that outputs a signal to the compensation voltage generation circuit, wherein

the signal dictates the compensation voltage.

3. The constant-temperature oscillator according to claim 2, wherein

the arithmetic circuit has a memory that stores data for setting the signal.

4. The constant-temperature oscillator according to claim 3, wherein

the data is a coefficient of a linear polynomial expression related to the compensation voltage.

5. The constant-temperature oscillator according to claim 3, wherein

the data is a coefficient of a cubic polynomial expression related to the compensation voltage.

6. The constant-temperature oscillator according to claim 3, wherein

the data is a coefficient of a fifth-order polynomial expression related to the compensation voltage.

7. A method for manufacturing a constant-temperature oscillator, comprising:

providing;

a vibrator that has a zero temperature coefficient as a frequency-temperature characteristic,

an oscillation circuit that excites the vibrator,

a voltage-controlled capacitance circuit that configures a resonant circuit with the vibrator,

a temperature controller that controls a temperature of the vibrator so as to adjust the temperature to a predetermined temperature,

a compensation voltage generation circuit that outputs a compensation voltage to the voltage-controlled capacitance circuit, the compensation voltage compensating an oscillating frequency deviation between a first oscillating frequency of the oscillation circuit when the vibrator is at a zero temperature coefficient temperature and a second oscillating frequency of the oscillation circuit when the vibrator is at the predetermined temperature, and

a memory that stores data for determining the compensation voltage;

measuring the zero temperature coefficient temperature of the vibrator;

storing the zero temperature coefficient temperature into the memory;

heating the vibrator to the predetermined temperature by the temperature controller;

storing the data associated with a temperature difference between the zero temperature coefficient temperature and the predetermined temperature and associated with the oscillating frequency deviation;

providing the compensation voltage to the voltage-controlled capacitance circuit from the compensation voltage generation circuit; and

adjusting an oscillating frequency of the constant-temperature oscillator.

8. The method for manufacturing a constant-temperature oscillator according to claim 7, wherein

the data is a coefficient of a linear polynomial expression related to the compensation voltage.

9. The method for manufacturing a constant-temperature oscillator according to claim 7, wherein

the data is a coefficient of a cubic polynomial expression related to the compensation voltage.

10. The method for manufacturing a constant-temperature oscillator according to claim 7, wherein

the data is a coefficient of a fifth-order polynomial expression related to the compensation voltage.

11. A frequency voltage control circuit, comprising:

an oscillation circuit that excites a vibrator that has a zero temperature coefficient as a frequency-temperature characteristic;

a voltage-controlled capacitance circuit that compensates an oscillating frequency of the oscillation circuit;

a temperature controller that controls a temperature of the vibrator so as to adjust the temperature to a predetermined temperature; and

a compensation voltage generation circuit that outputs a compensation voltage to the voltage-controlled capacitance circuit, wherein

the compensation voltage compensates an oscillating frequency deviation between a first oscillating frequency of the oscillation circuit when the vibrator is at a zero temperature coefficient temperature and a second oscillating frequency of the oscillation circuit when the vibrator is at the predetermined temperature.

12. The frequency voltage control circuit according to claim 11, further comprising:

an arithmetic circuit that outputs a signal to the compensation voltage generation circuit, wherein

the signal dictates the compensation voltage.

13. The frequency voltage control circuit according to claim 12, wherein

the arithmetic circuit has a memory that stores data for setting the signal.

14. The frequency voltage control circuit according to claim 13, wherein

the data is a coefficient of a linear polynomial expression related to the compensation voltage.

15. The frequency voltage control circuit according to claim 13, wherein

the data is a coefficient of a cubic polynomial expression related to the compensation voltage.

16. The frequency voltage control circuit according to claim 13, wherein

the data is a coefficient of a fifth-order polynomial expression related to the compensation voltage.