| 摘要 |
PURPOSE:To make a position detecting device compact and to eliminate malfunction by reflecting light emitted from a light emitting means by a light reflecting means stuck to the outer periphery of a cam frame and providing a main body having a hole through which light is received by a light receiving means. CONSTITUTION:The light reflecting means 6 is provided on the outer periphery of the cam frame 3 and the main body 11 having the hole 1b through which the light emitted from the light emitting means 8a and the light reflected by the light reflecting means 6 pass is also provided. By sticking the light reflecting means 6 on the outer periphery of the cam frame 3 and forming the hole 1b on the main body 1 positioned between the light reflecting means 6 and the light emitting means 8a and the light receiving means 8b, the emission, the reflection and the reception of the light can be sensed and the respective means for emitting the light, for reflecting the light and for receiving the light are housed in a zoom ring. Then, the light reflecting means 6, the light emitting means 8a and the light receiving means 8b are covered with the zoom ring, so that the external light is prevented from entering. Thus, the compact position detecting device without malfunction is obtained. |
