| 摘要 |
PURPOSE:To prevent the malfunction due to external diffused light by forming a metallic shielding plate, which is placed between the aperture edge of a tube part and an optical system block and covers this aperture edge, as one body with a housing. CONSTITUTION:A metallic housing in which a pyroelectric, element 6, etc. are arranged consists of a hemispherical rotating body 12 and a cover body 10 covering the aperture face of the rotating body 12. The output from the element 6 is amplified by an amplifying circuit mounted on a printed board arranged in the rotating body 12 and is led to a processing circuit through a lead wire 14. Though unnecessary light such as external diffused light tries to strike a tube part 3 of the element 6, it strikes a shielding plate 5 because the shielding plate 5 is placed in the front of the aperture edge of the tube part 3, and heat due to this light is transmitted to the cover body 10 and is radiated but is not transmitted to the tube part 3; and thus, the element 6 is not affected and the malfunction is not caused therefore. |
