| 摘要 |
PURPOSE:To easily check damage, etc. of an optical system extending from a monitor window to a detecting element, by executing switching control so that an alarm is raised when an alarm circuit does not receive an output from the detecting element reversely to the time of usual monitor at the time of check. CONSTITUTION:A window part 1 consisting of a resin material transmitting infrared rays such as polyethylene, etc. having a roughly semicircular section is attached so as to surround a space of the front of a base 6, and a concave mirror 2a and an infrared-ray detecting element 3 for constituting an optical system are attached to the surface of the base 6 in the inside of this cover. A photodetecting surface 3a of the detecting element 3 usually sees a monitor frame area 1a of the window part 1 through the concave mirror 2a, but when a check is required, the element body moves to the diagonal upper part by a control mechanism 5, therefore, the window part 1 of the monitor window commands another visual field through a range which has been shifted from the monitor frame area 1a, as shown by a broken line.
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