Gyro-compass

• US 5,375,336 A
• Filed: 04/29/1993
• Issued: 12/27/1994
• Est. Priority Date: 05/08/1992
• Status: Expired due to Term

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Nakamura, Takeshi
• Primary Examiner(s): Fulton, Christopher W.
• Application Number:
  US08/053,659
• Time in Patent Office: 607 Days
• Field of Search: 33/324, 33/351, 33/318, 33/320, 33/322, 33/333, 33/354, 73/504, 364/443, 364/449, 364/453
• US Class Current: 33/324
• CPC Class Codes: G01C 19/5649 Signal processing

Abstract

A support base of an angular velocity sensor is supported rotatably at one end, and the support base is vibrated by a piezoelectric element. By this vibration, a known rotational angular velocity is applied to the angular velocity sensor. For example, a difference of two output signals of the angular velocity sensor is measured. This difference of the output signals is detected in synchronism with phases which differ from each other by 180°, in two synchronous detection circuits. The detected signal is smoothed in smoothing circuits, and further, amplified in amplifying circuits. An output signal of the amplifying circuit is composed in a variable resistor as a composite circuit. Meanwhile, from the output signal of the amplifying circuit, the output signal of the variable resistor and a signal corresponding to the known rotational angular velocity are subtracted.

Claims

1. A gyro-compass comprising:

an angular velocity sensor;

angular velocity applying means for applying a known rotational angular velocity to said angular velocity sensor;

a plurality of synchronous detection circuits for detecting an output signal of said angular velocity sensor in synchronism with different phases;

a plurality of smoothing circuits for smoothing output signals of said plurality of synchronous detection circuits;

a composite circuit for composing output signals of said plurality of smoothing circuits;

a differential circuit for obtaining a difference between one output signal of said plurality of smoothing circuits and an output signal of said composite circuit; and

a separate differential circuit for obtaining a difference between an output of said differential circuit and a signal corresponding to the known rotational angular velocity applied by said angular velocity applying means.

2. A gyro-compass in accordance with claim 1, wherein by detecting the output signal of said angular velocity sensor at the phase difference of 180°

respectively in said plurality of synchronous detection circuits, a positive portion and a negative portion of the output signal of said angular velocity sensor are detected.

3. A gyro-compass in accordance with claim 1, wherein said composite circuit is a variable resistor.

4. A gyro-compass in accordance with claim 1, wherein said angular velocity applying means includes piezoelectric elements for generating vibration within a circle about said angular velocity sensor, and an oscillation circuit for driving said piezoelectric elements, and a signal corresponding to a known rotational angular velocity is obtained by smoothing an output signal of said oscillation circuit.

5. A gyro-compass in accordance with claim 1, wherein said angular velocity sensor is a vibrating gyroscope utilizing bending and vibrating movement of a columnar vibrator.

6. A gyro-compass in accordance with claim 5, wherein said vibrating gyroscope includes said vibrator of triangular columnar shape and piezoelectric elements formed on the side faces of said vibrator.

7. A gyro-compass in accordance with claim 4, wherein a difference of output signals obtained from two piezoelectric elements among said piezoelectric elements formed on said vibrating gyroscope is input to said synchronous detection circuits.

8. A gyro-compass in accordance with claim 5, wherein said vibrating gyroscope is bent and vibrated by a driving circuit consisting of an oscillation circuit and a phase circuit, and a signal for synchronous detection is applied to said synchronous detection circuit from said phase circuit.