| 摘要 |
PROBLEM TO BE SOLVED: To provide an obstacle detection device having a plurality of tiers of light projectors/receivers 9 and 10 installed along a guide rail 6 that restarts obstacle detection control by projecting and receiving light with light projectors/receivers 9-1 to i and 10-1 to i on i-th tier and above, when light projection and reception has been blocked for the light projectors/receivers 9-i and 10-i on the i-th tier due to adhesion of a foreign matter or other defects without a stop command, in a course of opening operation of a shutter curtain 4.SOLUTION: In a case of blocking of light projection/reception by the light projectors/receivers 9-i and 10-i on the i-th tier in a course of opening operation of the shutter curtain 4 and furthermore light projection/reception by the light projectors/receivers 9-1 and 10-1 on a topmost tier, obstacle detection control is restarted through light projection/reception by the light projectors/receivers 9-1 to i and 10-1 to i on the i-th tier and above, thus disabling a closing operation due to detection of an abnormality of the light projectors/receivers 9-i and 10-i in a next closing operation of the shutter curtain 4.SELECTED DRAWING: Figure 8 |
