Patent ID: 6148671
Filing Date: 2000-11-21
Classification: G01P

Abstract:
An acceleration sensor comprising:a piezoelectric ceramic substrate;a surface electrode pattern formed on a front surface of said piezoelectric ceramic substrate and including acceleration detecting electrodes for generating a signal depending on acceleration, output electrodes for externally outputting an output of said acceleration detecting electrodes and wiring patterns for electrically connecting said acceleration detecting electrodes and output electrodes to each other therethrough;a counter electrode pattern formed on a rear surface of said piezoelectric ceramic substrate and arranged opposite to at least said acceleration detecting electrodes;a weight arranged in a manner to be fixed with respect to said piezoelectric ceramic substrate to generate stress depending on said acceleration in a region in which said acceleration detecting electrodes are arranged; andlow-dielectric layers arranged between all of said wiring patterns or an essential part thereof and said piezoelectric ceramic substrate;said low-dielectric layers being substantially reduced in relative dielectric constant and being of sufficient thickness, as compared with that of said piezoelectric ceramic substrate so that any loss in the acceleration signal outputted from each of said output electrodes due to an electrostatic capacity formed between said wiring patterns and output electrodes, and said counter electrode pattern is minimized;said piezoelectric ceramic substrate being polarized at a portion thereof between said acceleration detecting electrodes and said counter electrode pattern.