| 摘要 |
PURPOSE:To keep the recording density of a copying machine constant and to perform the stable control of the machine by automatically adjusting the control target value of the concentration of developer in a developing means and automatically adjusting bias voltage for the developing means in accordance with the density of an original surface. CONSTITUTION:The bias voltage for the developing means 3-6 is set in accordance with the ratio of the light reflectance OD1 of a reference density pattern means 22 to the light reflectance OD2 of the actual original surface. Namely, since the density of the reference density pattern means 22 is constant, the developing bias voltage is automatically adjusted in accordance with the actual density of the original. Then, the control target value of the concentration of the developer in the developing means 3-6 is set in accordance with the light reflectance of a toner image with comparatively high density which is formed on a charge carrier 19 such as a photosensitive body, that means, a 2nd recording density ID2. Thus, the control target value of the concentration of the developer is adjusted lest the actual concentration of the developer should be changed greatly, whereas there is no possibility that the scattering of toner caused by the excessive replenishment of toner occurs. |
