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US 2006/0123908 A1Published application
Gyro sensor
AssigneeDenso Corporation
InventorHajime Ito
Life of this patent
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Abstract
The electrostatically-driven/capacitance-detection type gyro sensor has a sensing element including a movable part, the sensitivity of the sensing element and accordingly the sensitivity of a sensor output signal thereof being kept unchanged by controlling the amplitude of displacement or displacing velocity of the movable part and by using a reference voltage independent of variation of a power supply voltage, even there occurs a change in the vibrating state of the movable part due to temperature change or secular variation.
Claims6
An electrostatically-driven/capacitance-detection type gyro sensor comprising:
- a sensing element including
- a movable part displaceable in a motion plane,
- a first electrode provided in said movable part and applied with a bias voltage;
- a second electrode applied with a drive signal to generate an electrostatic force acting on said movable part in order that said movable part vibrates along a first direction on said motion plane,
- a third electrode forming a first variable capacitor with said movable part, a capacitance of said first variable capacitor varying in accordance with a displacement of said movable part along said first direction, and
- a fourth electrode forming a second variable capacitor with said movable part, a capacitance of said second variable capacitor varying in accordance with a displacement of said movable part along a second direction on said motion plane, said second direction being orthogonal to said first direction;
- a reference voltage generator generating, from a power supply voltage supplied from outside said gyro sensor, a reference voltage which is constant irrespective of variation of said power supply voltage;
- a bias voltage generator generating said bias voltage by amplifying said reference voltage;
- a capacitance-voltage converter converting said capacitance of said first variable capacitance into a first voltage signal whose voltage level varies following variation of said capacitance of said first variable capacitor, and converting said capacitance of said second variable capacitance into a second voltage signal whose voltage level varies following variation of said capacitance of said second variable capacitor;
- a drive signal generator generating said drive signal by amplifying and phase-adjusting said first voltage signal, said drive signal having an offset voltage proportional to said reference voltage;
- and
- a sensor output signal generator generating, from said second voltage signal, a sensor output signal having a magnitude corresponding to said voltage level of said second voltage signal, said sensor output signal having an offset voltage proportional to said power supply voltage.
9 more elements
Dependencies are inferred from the claim text.