| 摘要 |
<p>PURPOSE:To detect the presence of a transparent substrate or an opaque substrate without contacting. CONSTITUTION:In a wafer counter 3 for counting wafers W in a carrier C, a light directing and receiving sensor and a light receiving sensor are so located that the light directing and receiving surface and a light receiving surface face each other, a pair of these sensors is considered as one set, for instance, 25 sets of them in total are arranged in the length direction of a sensor board 31, and a judging portion is provided, to which either a light receiving signal from the light receiving portion of the light directing and receiving sensor or a light receiving signal from the light receiving portion of the light receiving sensor can be input by switching. The presence or absence of a substrate can be detected without contact by the presence or absence of the light receiving signal at the light receiving portion of the light directing and receiving sensor due to reflected light in the case of a transparent substrate and, on the other hand, by the presence or absence of the light receiving signal at the light receiving portion of the light receiving sensor due to incident light in the case of opaque substrate.</p> |
