| 摘要 |
PURPOSE:To generate a secure light signal even on the condition wherein the temperature may rise by providing blades along slits of a code wheel stored in a casing and providing an air vent to the casing. CONSTITUTION:The air vent 8 is bored in the circumferential barrel part of the casing 1 and this air bent is provided with a baffleplate to prevent the entrance of stray light. The code wheel 8 is fitted to a rotating shaft 2 pivoted in the casing 1, and a light emitting element 4 such as an LED and a photodetecting element 5 such as a photodiode are arranged facing each other with the wheel 3 inbetween. Further, blades 11 are provided along slits 7 of the code wheel 3 radially from the circumferential side to the center of the code wheel. Consequently, a temperature rise is prevented in the casing and the light signal is prevented from becoming inaccurate. |
