Patent ID: 6657762
Filing Date: 2003-12-02
Classification: G01V

Abstract:
An optical barrier apparatus comprising a first unit and a second unit facing each other with a detection area therebetween,wherein each of said first and second units comprises: optical beam generating means; optical beam scanning means for reflecting an optical beam generated by said optical beam generating means so as to scan an area containing said detection area; optical beam reflecting means for reflecting a scanning beam incident from said optical beam scanning means via said detection area by turning back at approximately 180 degrees; light receiving means arranged in the vicinity of said optical beam scanning means for receiving a reflection beam from said optical beam reflecting means; and signal deficiency detecting means for detecting the presence/absence of a deficiency of output signal of said light receiving means and generating a notification output for object absence at the time of no deficiency, and wherein the optical beam scanning means and the light receiving means of said first unit and the optical beam scanning means and the light receiving means of said second unit are arranged on either side of the detection area at approximately diagonal positions.