| 摘要 |
PURPOSE:To obtain a stable density picture without fail by detecting the density of a picture formed on a recording paper after picture development so as to control the makeup of an concentrated solution supplied to liquid toner. CONSTITUTION:A density detector 12 such as an optical sensor is installed the back of a developing unit 5 at a position where a developed detection patch 4 can be detected, and the picture density of the detection patch 4 after development is detected. After a density signal detected by the density detector 12 is A/D-converted by an A/D converter circuit 13, it is inputted to a density control circuit 14, in which a reference value is preset. If the picture density detected by the density detector 12 is lower than the reference value, a signal is transmitted to a drive circuit 15 to open a solenoid valve 9. Thus a pump 6 supplies the concentrated solution in a makeup tank 10 to the developing unit 5 together with the liquid toner in a tank 8. |
