Automatic measuring apparatus having a switching means to generate an output signal only when a sensor is positioned at a predetermined space

An automatic measuring apparatus comprising:

• distance sensor means mounted on one of a pair of surface plates which are rotatable with respect to each other with a plurality of carriers each holding a work piece being sandwiched therebetween for radiating an electromagnetic wave toward the other surface plate to thereby detect a distance thereto and for generating an analog signal representative of the thus detected distance;
• analog/digital conversion means for converting the analog signal from said distance sensor means into a corresponding digital voltage signal at a predetermined sampling frequency;
• switching means for allowing the digital voltage signals from said analog/digital conversion means to pass only when said distance sensor means is positioned at a space between said carriers;
• and
• arithmetic operation means for determining a thickness of each work piece based on a voltage value of a digital voltage signal having a maximum frequency among said digital voltage signals from said switching means.