| 摘要 |
PURPOSE:To make it possible to detect the concentration of the developing agent accurately and simply by providing a voltage applying means which switches and applies the voltages that absorb or repell the developing agent, in a detecting plane, which is arranged at the position equivalent to an image carrier position to which the developing agent is supplied. CONSTITUTION:A detecting window 5 for detecting the developing ability of the developing agent is arranged at the position similar to the developing position of a light detecting drum (the position at which the same action as the development of the light detecting drum 1 is perfomed by a developing sleeve 2). Said detecting window 5 is arranged so that a conducting plane 51 faces toward the side of the developing agent. Two voltages V1 and V2 (V1 is a toner attaching voltage and V2 is a cleaning voltage) are generated on the conductive plane 51 of the window 5 by a power source 9. When the developing sleeve 2 begins to rotate, the cleaning voltage V2 is applied to the detecting window 5 so that the drum 1 is cleaned. Then the attaching voltage V1 is applied so that the toner is attached to the detecting window. The detecting window 5 to which said toner is attached is lighted by a light source 6. The reflected light from the attached toner is received by a photocell 7, and converted into the electric signal. The signal is sent to a detecting circuit 8 and converted to the value indicating the developing ability. |
