Electronic apparatus

• US 20030169130A1
• Filed: 03/04/2003
• Published: 09/11/2003
• Est. Priority Date: 03/06/2002
• Status: Active Grant

• Current Assignee: Piedek Technical Laboratory
• Original Assignee: Piedek Technical Laboratory
• Inventors: Kawashima, Hirofumi
• Granted Patent: US 6,897,743 B2
• Time in Patent Office: Days
• US Class Current: 333/200
• CPC Class Codes: H03H 2003/026 the resonators or networks being of the tuning fork type
• CPC Class Codes: H03H 2003/0492 during the manufacture of a tuning-fork
• CPC Class Codes: H03H 9/0547 consisting of a vertical arrangement H03H9/0566 takes precedence
• CPC Class Codes: H03H 9/1021 the BAW device being of the cantilever type
• CPC Class Codes: H03H 9/215 consisting of quartz

Abstract

The electronic apparatus comprises a display portion and a quartz crystal oscillator at least, and said electronic apparatus comprises at least two quartz crystal oscillators. Also, each of two quartz crystal oscillators of the at least two oscillators comprises a quartz crystal oscillating circuit having an amplification circuit and a feedback circuit. The feedback circuit is constructed by a flexural mode, quartz crystal tuning fork resonator or a width-extensional mode quartz crystal resonator or a thickness shear mode quartz crystal resonator and for example, the quartz crystal tuning fork resonator comprising tuning fork tines and tuning fork base that are formed integrally, is shown with novel shape and electrode construction. Also, the quartz crystal tuning fork resonator, capable of vibrating in a fundamental mode and having a high frequency stability can be provided with a small series resistance and a high quality factor, even when the tuning fork resonator is miniaturized. This is accomplished by grooves, groove dimensions and electrode construction on the tuning fork tines and/or tuning fork base of the quartz crystal tuning fork resonator. In addition, from a relationship of an amplification rate and a feedback rate, the quartz crystal oscillator having an output signal of a frequency of the fundamental mode vibration for the quartz crystal tuning fork resonator can be provided with the high frequency stability.

Claims

1. An electronic apparatus comprising a display portion and a quartz crystal oscillator at least, said electronic apparatus comprising at least two quartz crystal oscillators, each of two quartz crystal oscillators of said at least two quartz crystal oscillators comprising:

a quartz crystal oscillating circuit comprising;

one quartz crystal resonator of at least two quartz crystal resonators which are capable of vibrating in a different mode, respectively, said each quartz crystal oscillator comprising said quartz crystal oscillating circuit comprising an amplification circuit comprising an amplifier at least and a feedback circuit comprising said one quartz crystal resonator and capacitors at least,

said one quartz crystal resonator being a quartz crystal tuning fork resonator capable of vibrating in a flexural mode, and said quartz crystal tuning fork resonator comprising;

tuning fork tines each of which has a length, a width and a thickness and the length greater than the width and the thickness; and

a tuning fork base;

said tuning fork tines and said tuning fork base that are formed integrally;

grooves provided at said tuning fork tines; and

electrodes disposed opposite each other inside the grooves and on sides of said tuning fork tines so that the electrodes disposed opposite each other are of opposite electrical polarity and said tuning fork tines are capable of vibrating in inverse phase, wherein said quartz crystal oscillating circuit comprises said quartz crystal tuning fork resonator whose figure of merit M₁ of a fundamental mode vibration is larger than figure of merit M₂ of a second overtone mode vibration to suppress the second overtone mode vibration and to get a high frequency stability for the fundamental mode vibration, and a ratio of an absolute value of negative resistance, |−

RL₁| of the fundamental mode vibration of said amplification circuit and series resistance R₁ of the fundamental mode vibration is larger than that of an absolute value of negative resistance, |−

RL₂| of the second overtone mode vibration of said amplification circuit and series resistance R₂ of the second overtone mode vibration,

and wherein an output signal of said quartz crystal oscillating circuit comprising said quartz crystal tuning fork resonator capable of vibrating in the flexural mode has a frequency of the fundamental mode vibration thereof and is outputted through a buffer circuit, and said output signal is a clock signal which is used to display time at said display portion of said electronic apparatus.

2. The electronic apparatus according to claim 1, wherein said frequency of the fundamental mode vibration is within a range of 10 kHz to 200 kHz.

3. The electronic apparatus according to claim 2, wherein a ratio of groove width W₂ and tine width W is larger than 0.35 and less than 1, and a ratio of groove thickness t₁ and tine thickness t is less than 0.79.

4. The electronic apparatus according to claim 2, wherein said amplification circuit comprises a CMOS inverter and a feedback resistor, and said feedback circuit comprises said quartz crystal tuning fork resonator, a drain resistor, a capacitor of a gate side and a capacitor of a drain side.

5. The electronic apparatus according to claim 3, wherein the groove width W₂ is constructed so that W₂≧

W₁, W₃ and a part or all of at least one of the grooves is constructed so that W₁≧

W₃ or W₁<

W₃.

6. The electronic apparatus according to claim 4, wherein one of said two quartz crystal oscillators comprises a quartz crystal oscillating circuit comprising a width-extensional mode quartz crystal resonator capable of vibrating in a width-extensional mode.

7. The electronic apparatus according to claim 4, wherein one of said two quartz crystal oscillators comprises a quartz crystal oscillating circuit comprising a thickness shear mode quartz crystal resonator capable of vibrating in a thickness shear mode.

8. The electronic apparatus according to claim 5, wherein a ratio of groove length l₁ and total length l is within a range of 0.2 to 0.78.

9. An electronic apparatus comprising a display portion and a quartz crystal oscillator at least, said electronic apparatus comprising at least two quartz crystal oscillators, each of two quartz crystal oscillators of said at least two quartz crystal oscillators comprising:

a quartz crystal oscillating circuit comprising;

one quartz crystal resonator of at least two quartz crystal resonators which are capable of vibrating in a different mode, respectively, said each quartz crystal oscillator comprising said quartz crystal oscillating circuit comprising an amplification circuit comprising an amplifier at least and a feedback circuit comprising said one quartz crystal resonator and capacitors at least,

said one quartz crystal resonator being a quartz crystal tuning fork resonator capable of vibrating in a flexural mode, and said quartz crystal tuning fork resonator comprising;

tuning fork tines each of which has a length, a width and a thickness and the length greater than the width and the thickness; and

a tuning fork base;

said tuning fork tines and said tuning fork base that are formed integrally;

grooves provided at said tuning fork tines; and

electrodes disposed opposite each other inside the grooves and on sides of said tuning fork tines so that the electrodes disposed opposite each other are of opposite electrical polarity and said tuning fork tines are capable of vibrating in inverse phase, wherein said quartz crystal oscillating circuit comprises said quartz crystal tuning fork resonator whose figure of merit M₁ of a fundamental mode vibration is larger than figure of merit M₂ of a second overtone mode vibration to suppress the second overtone mode vibration and to get a high frequency stability for the fundamental mode vibration, and a ratio of an amplification rate α

₁ of the fundamental mode vibration and an amplification rate α

₂ of the second overtone mode vibration of said amplification circuit is larger than that of a feedback rate β

₂ of the second overtone mode vibration and a feedback rate β

₁ of the fundamental mode vibration of said feedback circuit and a product of the amplification rate α

₁ and the feedback rate β

₁ of the fundamental mode vibration is larger than 1,

and wherein an output signal of said quartz crystal oscillating circuit comprising said quartz crystal tuning fork resonator capable of vibrating in the flexural mode has a frequency of the fundamental mode vibration thereof and is outputted through a buffer circuit, and said output signal is a clock signal which is used to display time at said display portion of said electronic apparatus.

10. The electronic apparatus according to claim 9, wherein said frequency of the fundamental mode vibration is within a range of 10 kHz to 200 kHz.

11. The electronic apparatus according to claim 10, wherein said quartz crystal oscillating circuit comprises a CMOS inverter, a feedback resistor, said quartz crystal tuning fork resonator, a drain resistor, a capacitor of a gate side and a capacitor of a drain side.

12. An electronic apparatus comprising a display portion and a quartz crystal oscillator at least, said electronic apparatus comprising at least two quartz crystal oscillators, each of two quartz crystal oscillators of said at least two quartz crystal oscillators comprising:

a quartz crystal oscillating circuit comprising;

one quartz crystal resonator of at least two quartz crystal resonators which are capable of vibrating in a different mode, respectively, said each quartz crystal oscillator comprising said quartz crystal oscillating circuit comprising an amplification circuit comprising an amplifier at least and a feedback circuit comprising said one quartz crystal resonator and capacitors at least,

said one quartz crystal resonator being a width-extensional mode quartz crystal resonator capable of vibrating in a width-extensional mode, and said width-extensional mode quartz crystal resonator comprising;

a vibrational portion having a length greater than a width and a thickness smaller than the width;

connecting portions located at ends of said vibrational portion;

supporting portions connected to said vibrational portion through said connecting portions; and

electrodes disposed on upper and lower faces of said vibrational portion, wherein a piezoelectric constant e₁₂ of said resonator is within a range of 0.095 C/m² to 0.18 C/m² in the absolute value,

and wherein an output signal of said one quartz crystal oscillator comprising said width-extensional mode quartz crystal resonator is outputted through a buffer circuit, and said output signal is a clock signal which is used except time display of said electronic apparatus.

13. The electronic apparatus according to claim 12, wherein a cutting angle of said resonator is within a range of XZtw(−

25+-+25°

)/(−

30°

-+30°

).

14. The electronic apparatus according to claim 12, wherein a cutting angle of said resonator is within a range of XZt(−

12°

-−

13.5°

) or XZt(−

18.5°

-−

19.8°

) or XZtw(−

13°

-−

18°

)/±

(+0.5°

-+30°

).

15. The electronic apparatus according to claim 12, wherein said quartz crystal oscillating circuit comprises a CMOS inverter, a feedback resistor, said width-extensional mode quartz crystal resonator, a drain resistor, a capacitor of a gate side and a capacitor of a drain side.