公开(公告)号：EP0825458A4

公开(公告)日：1998-07-01

申请号：EP97906865

申请日：1997-03-10

申请人： NIHON SHINGO KABUSHIKI KAISHA

发明人： ASADA NORIHIRO ,  FUTSUHARA KOICHI

IPC分类号： G01V8/10 ,  G01V8/12 ,  G01V8/20 ,  G01V8/26

CPC分类号： G01V8/10 ,  G01V8/12 ,  G01V8/20 ,  G01V8/26

摘要： A laser beam generated by a laser beam source (201) is reflected on a semiconductor galvanomirror (102) to allow the reflected beam (106) to scan a region (105) to be detected. The laser beam (106) passing through the region (105) is received by a photodetector array (130). An output pulse train from the photodetector array(130) is monitored by a signal processing circuit (206). When an obstruction enters the region (105) and causes some missing pulses in the pulse train, that incident is detected by a pulse detecting circuit (204). This configuration provides a low-cost optical barrier without spoiling the fail-safe characteristics thereof.