Acceleration sensor
AssigneeMurata Manufacturing Co., Ltd.
InventorMuneharu Yamashita
Life of this patent
Estimating the term…
Abstract
An acceleration sensor includes a bridge circuit including two capacitors and two piezoelectric vibrators on which reverse stresses are exerted by acceleration, and a voltage-dividing impedance circuit provided between a second junction point and a third junction point. The signal of a voltage-dividing point of the voltage-dividing impedance circuit is fed back to a first junction point, so that an oscillation circuit is provided. An oscillating-output phase difference between the second and third junction points is detected by a phase-difference-signal processing circuit and is output as an acceleration-detection signal.
Claims20
An acceleration sensor comprising:
- first and second piezoelectric vibrators in which reverse stresses are generated by acceleration;
- a bridge circuit that includes a first impedance circuit including the first piezoelectric vibrator, a second impedance circuit including the second piezoelectric vibrator, a first load impedance circuit including a first capacitor, and a second load impedance circuit including a second capacitor, said first impedance circuit and said second impedance circuit are connected to a first junction point, said first impedance circuit and said first load impedance circuit are connected to a second junction point, said second impedance circuit and said second load impedance circuit are connected to a third junction point, and said first load impedance circuit and said second load impedance circuit are connected to a fourth junction point having a potential which defines a reference potential;
- a voltage-dividing impedance circuit provided between said second junction point and said third junction point;
- a feedback-signal processing circuit for feeding back the signal of a voltage-dividing point of said voltage-dividing impedance circuit to said first junction point;
- wherein
- an oscillating circuit is arranged;
- and
- a phase-difference-signal processing circuit which detects an oscillation-output-phase difference between said second junction point and said third junction point and which outputs an acceleration-detection signal.
An acceleration sensor comprising:
- first and second piezoelectric vibrators in which reverse stresses are generated by acceleration;
- a bridge circuit that includes a first impedance circuit including the first piezoelectric vibrator, a second impedance circuit including the second piezoelectric vibrator, a first load impedance circuit including a first capacitor, and a second load impedance circuit including a second capacitor, said first impedance circuit and said second impedance circuit are connected to a fourth junction point, said first impedance circuit and said first load impedance circuit are connected to a second junction point, said second impedance circuit and said second load impedance circuit are connected to a third junction point, and said first load impedance circuit and said second load impedance circuit are connected to a first junction point having a potential used as a reference potential;
- a voltage-dividing impedance circuit provided between said second junction point and said third junction point;
- a feedback-signal processing circuit for feeding back the signal of a voltage-dividing point of said voltage-dividing impedance circuit to said first junction point;
- whereby an oscillating circuit is provided;
- and
- a phase-difference-signal processing circuit which detects an oscillation-output-phase difference between said second junction point and said third junction point and which outputs an acceleration-detection signal.
Dependencies are inferred from the claim text.