| 摘要 |
PURPOSE: To allow a light transmission plate to be fitted to a casing without using any other members and to make the whole device thinner and light weight. CONSTITUTION: A casing 3, on the side where a wire-shaped light source 7 of the light transmission plate 6 is situated, is provided with projection 3a, and fulfills its duty to control the detaching of the light transmission plate 6. The light transmission plate 3 has a wedge shape with the first end surface 6a on the wire-shaped light source 7 side being thick and the second end surface 6b on the opposite side being thin in thickness to make the gross weight light. A recessed groove 3b having a U-letter shaped section is formed in the casing 3 so as to be fitted with the second end surface 6b. Further, both side surface of the light transmission plate 6 to be fitted with an approximately L-letter shaped notched part is provided with protruding parts 6c biased toward one side of the thickness direction of the light transmission plate 6. Rigidity as a whole is improved for inserting the light transmission plate 6 into the casing 3, and further, erroneous vertical and lateral insertion of the light transmission plate 6 at the time of assembly is prevented because the protruding part 6c of the light transmission plate 6 is biasedly installed. |
