Patent ID: 7281427

Claim:
An acceleration sensor, comprising: a frame section having an X axis, a Y axis and a Z axis of a three-dimensional coordinate system; a mass section disposed inside the frame section; a beam section including a plurality of X-direction beam elements extending in an X axis direction and a plurality of Y-direction beam elements extending in a Y axis direction, for flexibly connecting the mass section to the frame section by the plurality of X-direction beam elements and the plurality of Y-direction beam elements; a plurality of X-axis piezo-resistor pairs associated with the plurality of X-direction beam elements, respectively, each said X-axis piezo-resistor pair including a first X-axis piezo-resistor with a first length disposed in contact with one end of the associated X-direction beam element, and a second X-axis piezo-resistor with the first length disposed in contact with the other end of the associated X-direction beam element; a plurality of Y-axis piezo-resistor pairs associated with the plurality of Y-direction beam elements, respectively, each said Y-axis piezo-resistor pair including a first Y-axis piezo-resistor with the first length disposed in contact with one end of the associated Y-direction beam element, and a second Y-axis piezo-resistor with the first length disposed in contact with the other end of the associated Y-direction beam element; and a plurality of Z-axis piezo-resistor pairs associated with the plurality of X-axis piezo-resistor pairs, respectively, each said Z-axis piezo-resistor pair including a first Z-axis piezo-resistor with a second length disposed in the vicinity of the first X-axis piezo-resistor of the associated X-axis piezo-resistor pair, and a second Z-axis piezo-resistor with the second length disposed in the vicinity of the second X-axis piezo-resistor of the associated X-axis piezo-resistor pair, the second length being greater than the first length.