Patent ID: 7134339

Claim:
An acceleration sensor comprising: a base plate; and first and second resonators each including a piezoelectric material and each having electrodes on two opposite main surfaces thereof, each of the first and second resonators having a vibrating section at an intermediate portion of the resonator with respect to the longitudinal direction thereof; wherein the first and second resonators are attached to opposite sides of the base plate with respect to a direction in which acceleration is applied so as to define an acceleration-sensor element, only one longitudinal end of the acceleration-sensor element is fixed and the other longitudinal end of the acceleration-sensor element is free such that the first and second resonators bend in the same direction in response to the acceleration, and changes in frequency or changes in impedance in the first and second resonators caused by the bending of the acceleration-sensor element are differentially detected in order to detect the acceleration, the acceleration-sensor element is bendable about a central bending plane in response to the acceleration, the central bending plane being positioned at a central portion of the base plate with respect to the application direction of acceleration, and the vibrating section of each of the first and second resonators is disposed closer to the fixed longitudinal end than to the free longitudinal end of the acceleration-sensor element.