| 摘要 |
PURPOSE:To reliably monitor the wear of a brush by providing a deflector to flow brush cooling air through the light emitting front surface to a brush side when optically monitoring the wear of the brush, thereby preventing wear powder or dusts from adhering to the light emitted surface. CONSTITUTION:When a light emitting unit and a photoreceptor are disposed at both sides of a brush holder to optically detect the wear of a brush by the movement of the holder to monitor the wear of the brush, a deflector 20 is provided around the light emitting unit 10. The deflector 20 is so formed in the shape that brush cooling air 19 passes the front surface of the light emitting surface 17 of the unit 10 to flow smoothly to the brush side. Thus, since the wear powder or dusts generated by the wear of the brush do not adhere to the surface 17, the light emitter from the unit 10 can be always held constantly. |
