| 摘要 |
<p>PURPOSE:To sense the sticking extent of dust in a shelf by standing a dust sticking net between a light emitting element and a light receiving element provided on a printed board mounted in the shelf and operating a warning device outside the shelf when the dust sticks on the net to shield a photodetecting circuit. CONSTITUTION:The light emitting element 31 and light receiving element 32 are provided opposite each other on the printed board 2 packaged in the shelf 1. Further, the dust sticking net 4 is stood between the elements 31 and 32 to form the photodetecting circuit 3 which detects the quantity of light passing through the net 4 from the element 31 by the element 32. Then the warning device 5 which can be recognized outside the shelf 1 is connected to the detecting circuit 3 and when the dust sticks on the net 4 to interrupt the optical path of the detecting circuit 3, the warning device is put in operation. Therefore, the sticking state of the dust can be sensed from outside without extracting the board 2 from the shelf 1. Consequently, maintenance inspection is performed at a proper time and the operation efficiency of the system is improved.</p> |
