PURPOSE: To protect a sensor from high temperature, high humidity, and dust, by a method wherein a cover for covering a peripheral wall of a case for a sensor employing a scanning line such as ray of light, heat rays is placed, cooling air is caused to run between the peripheral wall and the cover, and the cooling air is caused to blow against the front of a sensor window.
CONSTITUTION: A front window 9 is placed at an expansion chamber 7 consisting of a projecting chamber 9 provided with a sensor element 11 emitting infrared rays to, for example, a scanning line, and a light receiving chamber 10 provided with light receiving sensors 13 and 16, and a cover 20 is positioned so that an air flow path 25 is formed between the cover 1 and a peripheral wall 2 of a case 1 incorporating a circuit substrate 27 consisting of a printed substrate. An air-guiding window 24 in a spiral is formed in a projection on an inner surface of a peripheral wall 21 of the cover 20. A slit-shaped air exhaust hole 26 is formed between a front wall 3 of the case 1 and a front wall 22 of the cover 20 and in an upper part of the front of the window 6. This causes air to blow against a transparent plate 7 of the window 6. This enables a sensor to reliably operate even under a severe condition such as high temperature and high humidity, or dusty place.
KAMIMURA KIYOHARU
TAMAOKI MASAKATSU
SUNX LTD