JPS5719638A - Inspection for air leak of wrist watch - Google Patents

Abstract

PURPOSE:To enable to perform an accurate inspection to find whether a water proof is good or bad, by a method wherein the occurrence of air leak can be decided even if a distortion amount of a glass or a reverse lid diminishes while the inside of a capsul is increased in an air pressurization. CONSTITUTION:An output C of a comparator 14 is a >b as shown in a drawing while a distortion signal voltage (a) increases, and thereby it is a high level ''H''. Meanwhile, it is a <b when the distortion signal voltage (a) is 1% or more lower than a peak value, and thereby it is designed to be brought into a low level ''L'' through the inversion of the output (c) of the comparision 14. Even if the distortion signal voltage (a) changes as shown in a solid line, a voltage (b) changes as shown in a dashe line, and the output of the comparator 14 is once brought into ''L'' from ''H'' and brought into ''H'' again for the duration of an air pressure increasing time T1. Thus, even in this case, it is decided that an air exists when the output (c) of the comparator 14 inverts to ''L'' from ''H''. As a result, when an air pressure becomes in a constant state, the air leak can be detected even if a distortion amount does not change, and this permits the improvement of a water proof test.