| 摘要 |
PURPOSE:To hold toner concentration constant and to maintain stable picture quality by decreasing or increasing the toner concentration set value of a toner concentration control mechanism with the lapse of time. CONSTITUTION:Relays 9-13 operate in order with a signal from an I/O port 18 and the voltage of a DC power source 15 is divided by a resistance 14 and one of the relays 9-13 and supplied to a terminal of a comparator 4 for a reference voltage Vts6. Namely, the value of the reference voltage Vts6 for the number of print pages is stepwise as shown by the relation graph between the number of print pages and reference voltage Vts. The concentration setting reference voltage Vts6 of a toner concentration control mechanism for a developer decreases with the lapse of time under said control as the number of print pages increases. Therefore, the concentration setting reference voltage Vts6 of the toner concentration control mechanism decreases eventually with the lapse of time, so the toner concentration can be held almost constant even if the number of print pages increases as shown by the relation graph between the number of print pages and toner concentration. Consequently, a formed image is stable. |
