| 摘要 |
<p>PROBLEM TO BE SOLVED: To accurately diagnose a sensor by using a means which shields the sensor and its operating means from a guarding environment. SOLUTION: When a guarding state is switched to a guarding cancel mode from a guarding mode, a control part 11 outputs a control signal to perform an operating test of a sensor 3. Thus, a shielding device control part 16 controls a shielding device 5 by the control signal and shields the sensor 3 and an infrared ray emitting part 4 from a guarding environment. Then the part 11 sends its control signal to a drive part 14, and the part 14 operates the part 4 to irradiate the infrared rays. If the sensor 3 does not sense a pattern as it is and no detection signal is sent to the part 11 from a detection part 13, the part 11 decides an abnormal operation of the sensor 3 and sends a facility abnormality alarm to a monitoring center. When the operating test is over, the part 16 controls the device 5 by the control signal sent from the part 11 to open the shielded sensor 3 and part 4.</p> |
