| 摘要 |
PURPOSE:To display the soil of a detector which detects the toner concentration of a toner image formed on a photosensitive body. CONSTITUTION:The controller of an electrophotographic copying machine which controls copying conditions based on the toner concentration of a reference target 3 is provided with a circuit which controls the gain of the amplifier of a control circuit by detecting the photosensitive body 6 by means of a detector 10 prior to the formation of the latent image of the reference target 3 on the photosensitive body 6, thereby obtaining the a constant final amplified output; and a means which judges whether the amplified output of the main amplifier of the circuit prior to the formation of the latent image of the reference target 3 on the photosensitive body 6 is within the fixed level or not and displays when the output is below the fixed level. |
