Piezoelectric vibration angular velocity meter and camera using the same

• US 5,765,046 A
• Filed: 04/10/1996
• Issued: 06/09/1998
• Est. Priority Date: 08/31/1994
• Status: Expired due to Term

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Nomura, Tatsushi, Sango, Yoshinori, Fujii, Toru, Watanabe, Shunji, Hattori, Tetsuo, Fujiu, Takamitsu
• Primary Examiner(s): PERKEY, WILLIAM B
• Application Number:
  US08/630,824
• Time in Patent Office: 790 Days
• Field of Search: 396/53, 73/504.14, 73/504.12, 310/348, 310/352, 310/351, 310/365, 310/366, 310/354
• US Class Current: 396/53
• CPC Class Codes: G01C 19/5642 using vibrating bars or beams

Abstract

A piezoelectric angular velocity meter includes a piezoelectric element. The piezoelectric element includes a first piezoelectric element and a second piezoelectric element bonded to the first piezoelectric element. The second piezoelectric element includes a second member made of a piezoelectric crystal, and upper- and lower-surface electrodes sandwiching the second member. The first piezoelectric element is fixed to the upper-surface electrode of said second piezoelectric element with an adhesive. The first piezoelectric element includes a first member made of a piezoelectric crystal, upper-surface electrodes, and a lower-surface electrode. The upper- and lower-surface electrodes sandwich the first member of the first piezoelectric element. The piezoelectric element is supported by two support portions.

Claims

1. A camera comprising:

a substrate;

a piezoelectric element; and

at least two support portions for supporting said piezoelectric element, said support portions being interposed between said substrate and said piezoelectric element,

wherein said piezoelectric element comprises a first piezoelectric element including,

a first member comprised of a piezoelectric crystal,

a left electrode arranged on an upper surface of said first member,

a right electrode arranged on the upper surface of said first member,

a middle electrode arranged between said left and right electrodes on the upper surface of said first member, and

a lower-surface electrode arranged on a lower surface of said first member.

2. A camera comprising:

a substrate;

a piezoelectric element; and

at least two support portions for supporting said piezoelectric element, said support portions being interposed between said substrate and said piezoelectric element,

wherein said piezoelectric element comprises;

a first piezoelectric element including,

a first member comprised of a piezoelectric crystal,

a left electrode arranged on an upper surface of said first member,

a right electrode arranged on the upper surface of said first member,

a middle electrode arranged between said left and right electrodes on the upper surface of said first member, and

a first lower-surface electrode arranged on a lower surface of said first member;

a second piezoelectric element including,

a second member comprised of a piezoelectric crystal,

an upper-surface electrode arranged on an upper surface of said second member, and

a second lower-surface electrode arranged on a lower surface of said second member; and

an adhesive interposed between said first and second piezoelectric elements.

3. A camera according to claim 2, further comprising:

wires respectively connected to said left electrode, said right electrode, said middle electrode, said upper-surface electrode, said first lower-surface electrode, and said second lower-surface electrode;

a circuit board having an upper surface to which said substrate is fixed, the upper surface having terminals to which said wires are respectively connected; and

a circuit unit arranged on a lower surface of said circuit board, said circuit unit including a circuit, electrically connected to the terminals, for applying an AC voltage to said piezoelectric element, and a circuit for processing a signal output from said piezoelectric element.

4. A camera according to claim 3, further comprising a lower case having a cavity in which said circuit unit is housed.

5. A camera according to claim 3, wherein said lower case includes at least two surfaces which support said circuit board in contact with the lower surface thereof.

6. A camera according to claim 3, further comprising:

a lower case having a cavity in which said circuit unit is housed; and

an upper case for housing said piezoelectric element, said upper case being fixed to said lower case with an adhesive.

7. A camera according to claim 2, further comprising:

a circuit for applying an AC voltage between said upper-surface electrode and said second lower-surface electrode; and

an automatic level control circuit for controlling an amplitude of the AC voltage generated by said circuit such that an amplitude of an AC voltage induced between said middle electrode and said first lower-surface electrode is kept constant.

8. A camera according to claim 7, wherein said automatic level control circuit comprises:

a first comparator for comparing a voltage induced between said middle electrode and said first lower-surface electrode with a first reference voltage, and outputting a voltage signal having a square wave;

a second comparator for comparing a voltage induced between said middle electrode and said first lower-surface electrode with a second reference voltage, and outputting a voltage signal having a square wave;

an integrating circuit for integrating the voltage signal output from said first comparator; and

a multiplier for multiplying the voltage signal output from said integrating circuit and the voltage signal output from said second comparator.

9. A camera according to claim 2, further comprising a differential amplifier for outputting a voltage signal representing a difference between a voltage signal output from said left electrode and a voltage signal output from said right electrode.

10. A camera according to claim 9, further comprising:

a housing in which a film is placed;

a lens, mounted in said housing, for forming an image of an object on the film;

a motor for moving said lens;

an A/D converter for converting the signal output from said differential amplifier into a digital signal; and

a central processing unit for receiving data output from said A/D converter and controlling said motor on the basis of the data.

11. A camera comprising:

a substrate;

a piezoelectric element; and

at least two support portions for supporting said piezoelectric element, said support portions being interposed between said substrate and said piezoelectric element,

wherein said piezoelectric element comprises;

a first member comprised of a piezoelectric crystal;

a lower-surface electrode arranged on a lower surface of said first member and having a rough surface;

a second member comprised of a piezoelectric crystal;

an upper-surface electrode arranged on an upper surface of said second member and having a rough surface; and

an adhesive layer interposed between said lower-surface electrode and said upper-surface electrode, said adhesive layer having a thickness larger than 0 mm and smaller than 1 mm, and said upper-surface electrode being electrically connected to said lower-surface electrode via said adhesive layer.

12. A device for detecting an angular velocity, comprising:

a substrate;

a piezoelectric element; and

at least two support portions for supporting said piezoelectric element, said support portions being interposed between said substrate and said piezoelectric element,

wherein said piezoelectric element comprises a first piezoelectric element including,

a first member comprised of a piezoelectric crystal,

a left electrode arranged on an upper surface of said first member,

a right electrode arranged on the upper surface of said first member,

a middle electrode arranged between said left and right electrodes on the upper surface of said first member, and

a lower-surface electrode arranged on a lower surface of said first member.

13. A device for detecting an angular velocity, comprising:

a substrate;

a piezoelectric element; and

at least two support portions for supporting said piezoelectric element, said support portions being interposed between said substrate and said piezoelectric element,

wherein said piezoelectric element comprises;

a first piezoelectric element including,

first member comprised of a piezoelectric crystal,

a left electrode arranged on an upper surface of said first member,

a right electrode arranged on the upper surface of said first member,

a middle electrode arranged between said left and right electrodes on the upper surface of said first member, and

a first lower-surface electrode arranged on a lower surface of said first member,

a second piezoelectric element including,

a second member comprised of a piezoelectric crystal,

an upper-surface electrode arranged on an upper surface of said second member, and

a second lower-surface electrode arranged on a lower surface of said second member; and

an adhesive interposed between said first and second piezoelectric elements.

14. A device for detecting an angular velocity, comprising:

a substrate;

a piezoelectric element; and

at least two support portions for supporting said piezoelectric element, said support portions being interposed between said substrate and said piezoelectric element,

wherein said piezoelectric element comprises;

a first member comprised of a piezoelectric crystal;

a lower-surface electrode arranged on a lower surface of said first member and having a rough surface;

a second member comprised of a piezoelectric crystal;

an upper-surface electrode arranged on an upper surface of said second member and having a rough surface; and

an adhesive layer interposed between said lower-surface electrode and said upper-surface electrode, said adhesive layer having a thickness larger than 0 mm and smaller than 1 mm, and said upper-surface electrode being electrically connected to said lower-surface electrode via said adhesive layer.