ANGULAR VELOCITY SENSOR AND SYNCHRONOUS DETECTION CIRCUIT USED THEREIN
First Claim
1. An angular velocity sensor comprising:
- an annular flexible portion arranged along an XY plane and having a center through which a Z axis passes through;
a mass portion supported on an inner edge of said flexible portion;
a support portion for supporting an outer edge of said flexible portion;
a driving portion for vibrating said mass portion in a direction of said Z axis;
a first piezoelectric element provided on a positive side of an X axis or a Y axis and having a first electrode fixed to a front surface of said flexible portion;
a second piezoelectric element provided on a negative side of said X axis or said Y axis and having a first electrode fixed to the front surface of said flexible portion; and
an operation circuit for finding an angular velocity around said Y axis or said X axis based on quantities of charge generated at the first and second electrodes of each of said first and second piezoelectric elements,wherein the first and second electrodes of said first piezoelectric element are connected to the second and first electrodes of said second piezoelectric element, respectively.
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Accused Products
Abstract
In an angular velocity sensor, an upper electrode of a first piezoelectric element and a lower electrode of a second piezoelectric element are connected to an input terminal of a first Q/V conversion circuit, and a lower electrode of the first piezoelectric element and an upper electrode of the second piezoelectric element are connected to an input terminal of a second Q/V conversion circuit. Thus, vibration noise components of the quantities of charge generated at the first and second piezoelectric elements are cancelled out, and Coriolis components of the quantities of charge generated at the first and second piezoelectric elements are added, whereby only the Coriolis components are extracted.
31 Citations
20 Claims
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1. An angular velocity sensor comprising:
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an annular flexible portion arranged along an XY plane and having a center through which a Z axis passes through; a mass portion supported on an inner edge of said flexible portion; a support portion for supporting an outer edge of said flexible portion; a driving portion for vibrating said mass portion in a direction of said Z axis; a first piezoelectric element provided on a positive side of an X axis or a Y axis and having a first electrode fixed to a front surface of said flexible portion; a second piezoelectric element provided on a negative side of said X axis or said Y axis and having a first electrode fixed to the front surface of said flexible portion; and an operation circuit for finding an angular velocity around said Y axis or said X axis based on quantities of charge generated at the first and second electrodes of each of said first and second piezoelectric elements, wherein the first and second electrodes of said first piezoelectric element are connected to the second and first electrodes of said second piezoelectric element, respectively. - View Dependent Claims (2, 3, 4)
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5. An angular velocity sensor comprising:
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an annular flexible portion arranged along an XY plane and having a center through which a Z axis passes through; a mass portion supported on an inner edge of said flexible portion; a support portion for supporting an outer edge of said flexible portion; a driving portion for vibrating said mass portion in a direction of said Z axis; and a detection portion for detecting an angular velocity around an X axis or a Y axis, based on vibration of said mass portion, said driving portion including a first piezoelectric element fixed to said flexible portion for vibrating said mass portion, a second piezoelectric element fixed to said flexible portion for detecting vibration of said mass portion, a driving circuit for providing a driving signal to said first piezoelectric element, a delay circuit for delaying a phase of said driving signal by 90 degrees, and a phase control circuit for comparing a phase of an output signal of said second piezoelectric element and a phase of an output signal of said delay circuit and controlling the phase of said driving signal such that a phase difference between these signals is eliminated. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12)
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13. A synchronous detection circuit for use in an angular velocity sensor, comprising:
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an analog switch; and an integration circuit including a resistor element and a capacitor, wherein a sensor signal including a driving signal component and an angular velocity signal component superposed on each other is input to an input terminal of said analog switch, and an input node of said integration circuit is connected to an output terminal of said analog switch, and ON/OFF of said analog switch is controlled by a sampling pulse having a same cycle as a cycle of said sensor signal, and a duty ratio of said sampling pulse is less than 50%. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification