| 摘要 |
PROBLEM TO BE SOLVED: To detect troubles such as optical misalignment and breakage in advance even when an obstacle sensor is constituted using a photoelectric sensor which does not have a self-checking function.SOLUTION: Troubles are detected in advance by checking whether a photoelectric sensor as sensing means is in normal operation by performing, for example, ON/OFF control over a light emission state of a projector of the photoelectric sensor as the sense means. The light emission state is ceased by cutting off supply of electric power to the projector of the sense means so as to create the same state with presence of an obstacle between the projector and light receiver of the photoelectric sensor, and then it is checked whether the photoelectric sensor is in normal operation by detecting whether an obstacle detection signal is output from the light receiver of the photoelectric sensor. The check on normalcy is made in a stop state of opening/closing means, namely, in a movement stop state after the opening/closing means is fully opened or fully closed, or in a state in which the opening/closing means stops halfway in opening operation or closing operation. |
