JPS6446609A - Plate thickness measuring instrument for body to be measured with film - Google Patents

Abstract

PURPOSE:To accurately measure the plate thickness of the body to be measured which does not includes a film from a border surface reflected wave and a bottom surface reflected wave extracted on the basis of a surface reflected wave. CONSTITUTION:A signal selector 22 selects the surface reflected wave, border surface reflected surface, and bottom surface reflected wave received by the receiving member 6 of an ultrasonic wave contactor 15. A comparator 25 which inputs the received wave (a) of the surface reflected wave and the received signal (b) of the border surface reflected wave outputs only a signal (c) based upon only the received signal (b) which is inputted with delay and a pulse gate circuit 34 which inputs the output signal (e) of an FF circuit 29 inputting the signal (c) and the received signal (d) of the bottom surface reflected wave and the output signal (f) of a timer pulse generator 33 outputs a signal (g) which is twice as large as the propagation time of the ultrasonic wave pulse of the body 10 to be measured; and this signal (g) is processed to find the plate thickness of the object body 10.