Sheet thickness measuring apparatus.

摘要

A sheet thickness measuring apparatus comprises a metallic back-up surface for supporting the sheet, a magnetic field utilizing sensor disposed above the metallic back-up surface and the sheet for outputting a measured value representative of a distance up to the metallic back-up surface, an optical sensor and a computing unit. The optical sensor comprises a light projecting unit for projecting a beam-like light on a position in the vicinity of the metallic back-up surface on which the sheet is disposed in a lateral direction and a light receiving unit for receiving the projected beam-like light which is disposed on an opposite side of the light projecting unit with respect to the light projected position, so that a measured value representative of the width along which the projected light is shielded by the metallic back-up surface and the sheet may be outputted on the basis of a change in the amount of the light shielded by the metallic back-up surface and the thickness of the sheet on the metallic back-up surface or the amount of the deviation of the position at which the light is shielded or the like. The computing unit computes the thickness of the sheet on the basis of the distance value measured by the magnetic field utilizing sensor and the value of the width of the shielded light measured by the optical sensor.