Angular velocity sensor with displacement scale and sensor means
First Claim
1. An angular velocity sensor comprising:
- a rod-like shaft having a specified portion thereof supported on a housing;
excitation means for vibrating a free end portion of said shaft in an X direction with a lengthwise axis of said shaft set in a Z direction of an XYZ rectangular coordinate system;
displacement sensing means for producing an output by sensing a displacement of the free end portion of said shaft in a Y direction; and
operation means for deriving an angular velocity about said shaft based on the output from said displacement sensing means;
wherein said displacement sensing means includes a main scale fixed on the free end portion of said shaft, an index scale fixed on said housing and confronting said main scale, a light emitting element for emitting light to illuminate said main scale, and a plurality of light sensors for sensing light which is reflected by said main scale and passed through said index scale.
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Accused Products
Abstract
In one type of an angular velocity sensor, a constant vibration is applied in an X direction to one end of a vibrator which is fixed at another end and the vibrator vibrates in a Y direction perpendicular to the X direction by an action of Coriolis force caused by the angular velocity of the vibrator about the Z axis with an amplitude proportional to an angular velocity about a Z axis. An angular velocity sensor of this invention utilizes a photoelectric encoder for measurement of the vibration amplitude of the vibrator in the Y direction. The encoder includes a main scale mounted on the free end of the vibrator; an index scale mounted on a housing of the sensor to face the main scale; and a photoelectric element for sensing light reflected from the main scale and passing through the index scale. The angular velocity sensor utilizing the photoelectric encoder is less subject to influence of variation in the temperature in comparison with the conventional sensor utilizing piezoelectric elements and a higher precision can be attained.
23 Citations
17 Claims
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1. An angular velocity sensor comprising:
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a rod-like shaft having a specified portion thereof supported on a housing; excitation means for vibrating a free end portion of said shaft in an X direction with a lengthwise axis of said shaft set in a Z direction of an XYZ rectangular coordinate system; displacement sensing means for producing an output by sensing a displacement of the free end portion of said shaft in a Y direction; and operation means for deriving an angular velocity about said shaft based on the output from said displacement sensing means; wherein said displacement sensing means includes a main scale fixed on the free end portion of said shaft, an index scale fixed on said housing and confronting said main scale, a light emitting element for emitting light to illuminate said main scale, and a plurality of light sensors for sensing light which is reflected by said main scale and passed through said index scale.
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2. An angular velocity sensor comprising:
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a rod-like shaft having a specified portion thereof supported on a housing; excitation means for vibrating a free end portion of said shaft in an X direction with a lengthwise axis of said shaft set in a Z direction of an XYZ rectangular coordinate system; displacement sensing means for producing an output by sensing a displacement of the free end portion of said shaft in the X direction and a Y direction; and operation means for deriving an angular velocity about said shaft based on the output from said displacement sensing means; wherein said displacement sensing means includes a main scale fixed on the free end portion of said shaft, an index scale fixed on said housing and confronting said main scale, a light emitting element for emitting light to illuminate said main scale, and a plurality of light sensors for sensing light which is reflected by said main scale and passed through said index scale.
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3. An angular velocity sensor comprising:
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a rod-like shaft having a specified portion thereof supported on a housing; excitation means for vibrating a free end portion of said shaft in an X direction with a lengthwise axis of said shaft set in a Z direction of an XYZ rectangular coordinate system; displacement sensing means for producing an output by sensing a displacement of the free end portion of said shaft in the X direction and a Y direction; control means for controlling said excitation means to keep constant a first signal of the output from said displacement sensing means, the first signal indicating a displacement in the X direction; and operation means for deriving an angular velocity about said shaft based on a second signal of the output from said displacement sensing means, the second signal indicating a displacement in the Y direction; wherein said displacement sensing means includes a main scale fixed on the free end portion of said shaft, an index scale disposed to face said main scale, a light emitting element for emitting light to illuminate said main scale, and a plurality of light sensors for sensing light which is reflected by said main scale and passed through said index scale. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification