Patent ID: 6769305
Filing Date: 2004-08-03
Classification: G01H,G01L,G01N,G01P

Abstract:
An acceleration sensor for detecting an acceleration caused by an object oscillated in an oscillation direction, comprising:a sensor casing having a center axis and to be positioned in coaxial alignment with said oscillation direction to receive said acceleration, said sensor casing having first and second circular inner surfaces opposing to and spaced apart along said center axis from each other at a first space distance less than 8.59 mm, and a third cylindrical inner surface connected at one end with said first inner surface and at the other end with said second inner surface to define a cylindrical closed space; an oscillation plate accommodated in said closed space of said sensor casing and having a central portion securely supported by said sensor casing and a peripheral portion integrally formed with said central portion and extending radially outwardly of said central portion to be freely movable with respect to said sensor casing, said oscillation plate having a peripheral end surface spaced apart from said third inner surface of said sensor casing at an annular gap small enough to enable said oscillation plate to oscillate with respect to said sensor casing, said oscillation plate having a first flat surface opposing to and spaced apart along said center axis from said first inner surface of said sensor casing at a second space distance, and a second flat surface opposing to and spaced apart along said center axis from said second inner surface of said sensor casing at a third space distance, said oscillation plate being partly oscillatable along said center axis with respect to said sensor casing; and a piezoelectric element having first and second surfaces and provided on at least one of said first and second flat surfaces of said oscillation plate to generate a voltage indicative of said acceleration when said acceleration is exerted on said sensor casing to have said oscillation plate partly oscillated along said center axis with respect to said sensor casing with said peripheral portion of said oscillation plate being deformed; in which said second space distance is less than or equal to the diameter of said third inner surface of said sensor casing multiplied by 0.1.