| 摘要 |
PURPOSE:To allow one light projecting element and one photodetector to be used respectively and to reduce the cost of a device by adjusting the light projection angle of the flux of light beams with the aid of a light projection angle changing means. CONSTITUTION:Infrared rays projected from the light projecting element 1 is condensed by a light projecting lens 3 to irradiate an object 2 and the reflected light from the object 2 is received by the photodetector 4 through a light receiving lens 5. The light projection angle of the flux of light beams projected from the element 1 is changed by moving the lens 3 back and forth in a light projecting direction. The lens 3 is attached to a movable lens holder 6 so as to constitute the light projection angle changing means 17. By driving a motor 13, the holder 6 is moved back and forth in the light projecting direction. When the output of the element 4 is not obtained for the small light projection angle of the means 17 but obtained for the large one, a specified signal output means transmits a signal to lens driving means to move an image pickup lens to a usual focusing direction, then the image pickup lens is moved to a position where focusing direction, then the image pickup lens is moved to a position where focusing is performed in an infinity distance when the output of the element 5 is not obtained for any light projection angle of the means 17. |
