| 摘要 |
PROBLEM TO BE SOLVED: To provide a bar-shaped lens with which the residual amount of toner is surely detected by eliminating the sticking of the toner to the body part surface of a lens and obtaining stable output. SOLUTION: The lens body parts of the bar-shaped lenses 7 and 8, which are the lenses for detection of the residual amount of the toner are covered with covering members 9 and 10, to cover the lens body part, and the toner 6 is stuck to the body parts of the covering members 9 and 10. Infrared rays, radiated from a light emitting element 2, are emitted while being reflected in the inside of the bar-shaped lens 7 disposed on the side of the light-emitting element 2, and the particles of the toner 6 float in the inside of a case 1 due to a toner stirring member 4 rotating and stick to the end faces of the bar- shaped lenses 7 and 8 and the outer peripheral surfaces of the coating members 9 and 10. The toner 6, striking to the end faces of the bar-shaped lenses 7 and 8, is scraped off by a lens-cleaning member 5 attached to the toner stirring member 4. The infrared rays, emitted by the bar-shaped lens 7, are transmitted, are made incident on the inside of the bar-shaped lens 8 on the side of a light- receiving element 3, and are reflected in inside thereof so that the rays are detected by the light-receiving device 3. |
