| 摘要 |
<p>The invention relates to a highly reliable mat sensor which can also detect temporary faults in a sensor portion. Two sensor portions (21, 22) are provided, and agreement or disagreement of an ON/OFF condition of the output from the two sensor portions (21, 22) is detected, and when the output conditions of the two sensor portions (21, 22) are in agreement, then a normal judgment signal (K) for both sensor portions (21, 22) is generated. When the normal judgment signal (K) is generated and the two sensor portions (21, 22) are OFF, an operation permit signal for a movable portion of a machine is generated. Moreover, the presence or absence of a body is detected from a change in value of the electrostatic capacity of one sensor portion (24). In this way, a temporary poor contact attributable to deterioration of the sensor portion can also be detected, and the movable portion of the machine can be stopped. <IMAGE></p> |
