| 摘要 |
PURPOSE:To reduce the down time of copying works by issuing an abnormality warning when the output of a density sensor becomes lower than a prescribed level due to the characteristic attenuation of the sensor and, at the same time, continuing the copying works under a preset condition thereafter so that picture density control can be performed. CONSTITUTION:A flexible optical fiber 19 provided with a light leading-in section 19a which leads rays of light containing density information from an original 2 based on detected rays of light 16 at one end and is connected with a position facing a photodetector 18 by the other end is provided and a density sensor is constituted of the fiber 19 and photodetector 18. The sensor issues an abnormality warning when the sensor output becomes lower than a preset prescribed level due to the characteristics attenuation of the sensor 18 and 19 and, at the same time, copying operations are continued under a preset reference processing condition so that picture density control can be performed. Therefore, even when automatic density control does not work properly, the copying operations are performed under a processing condition of a level which is considered to be a normal background density of originals. Thus copying operations can be performed even when the automatic density control does not work. |
