Patent ID: 8890054
Filing Date: 2014-11-18
Classification: G01B,G01V

Abstract:
1. A photoelectric sensor comprising: a phototransmitter configured to output light toward a detection target region of an object comprising a thin substrate; an optical receiver configured to receive the light outputted from the phototransmitter; a signal processing unit configured to output a signal indicating that the thin substrate is detected in response to a decrease of an amount of light received by the optical receiver; and two first optical filters that are provided between the phototransmitter and the optical receiver to transmit only pieces of light having specific characteristics, wherein, in the phototransmitter, two kinds of light having different characteristics which do not interfere with each other are outputted from output regions in the light transmitting surface, one of the two first optical filters has a characteristic of transmitting only one of the two kinds of light and the other of the first optical filters has a characteristic of transmitting only the other of the two kinds of light, the two first optical filters are disposed opposite to output regions of the pieces of light different from the pieces of light of a selecting target while located across a detection target region, two second optical filters having characteristics identical to those of the first optical filters are arrayed along the light transmitting surface so as to be opposite to the first optical filters having different characteristics, the second optical filters being located across the detection target region, and pieces of the light passing through the two second optical filters of the phototransmitter are outputted as the two kinds of light; output directions of the two kinds of light are fixed such that whole surfaces of the first optical filters corresponding to the characteristics are irradiated with the two kinds of light from the phototransmitter when the first optical filters are disposed in a light transmitting surface while located away from each other by a predetermined distance or more, each of the two kinds of light crosses diagonally the detection target region, an area where the two kinds of light crosses is configured to be a detection area where the thin substrate is detected; wherein the detection region has a width which extends from the first optical filters to the second optical filters, and a height which extends generally perpendicular to the width; and wherein the thin substrate has a height which is less than the height of the detection region.