THIN-DISK-STATE FORCE SENSOR

PURPOSE: To effect attachment without machining the peripheral part, by a thin disk type force sensor. CONSTITUTION: In order to evade breakdown of a fitted piezoelectric disk, measuring elements 6, 7 with a diameter of (d) which measure only partial force of the total screw force and eliminate danger of breakdown are used. The purpose of each of the measuring elements 6, 7 is to obtain the one which has rigidity as large as possible, i.e., discontinuous surface as little as possible because undesirable gap spring effect is contained in the elements. In order to restrain the influence of a gap spring layer which still exists, the measuring elements are welded to an annular measuring disk 14 under high mechanical preload. After that, the whole surface is ground and lap-finished as smooth as possible. In order to improve the force measurement ratio, a vapor deposition film 24 is formed on the surfaces of the measuring elements 6, 7. In many uses, it is advantageous to fit an impedance transformer as a preamplifier in a connector part.