| 摘要 |
PURPOSE:To always detect developer concentration by a normal developer concentration sensor by generating concentration data based on the output of plural developer concentration sensors and the discriminated result by a discriminating means. CONSTITUTION:The respective outputs from plural developer concentration detecting sensors 12 and 13 are compared to discriminate whether the actuated states of the sensors 12 and 13 are normal or abnormal by the discriminating means 15. Based on the output of the plural sensors 12 and 13 and the discriminated result by the discriminating means 15, a concentration data generating means 18 generates concentration detecting data from the output of the normal developer concentration sensor. Thus, the normal detection of the developer concentration is always executed, and the stable image density is secured even when some abnormality occurs in the sensors 12 and 13, thereby improving the image quality of a copying machine. |
