| 摘要 |
PURPOSE:To set a highly accurate control voltage to improve the reliability of a toner density sensor by finding the control voltage obtained by averaging control voltages when the difference between the highest control voltage and the lowest control voltage which are set for data obtained by performing control voltage setting operation plural times. CONSTITUTION:A voltage Vs obtained by the toner density sensor 35 correspond ing to the density of a developer is converted by an A/D converter 13 into a digital signal, which is sent to a controller 11. A slice voltage comparing circuit 11b in the controller 11 judges whether or not the digital signal is less than the permissible value DELTAV of the slice voltage Vt and sends a command signal for varying the control voltage Vc by a specific quantity to a control voltage adjusting circuit 11a when not to outputs a corresponding voltage signal to a D/A converter 12, so that the control voltage is varied stepwise to Vc1 and Vc2. This operation is repeated to put the output voltage Vs closer to the slice voltage Vt. When it is judged that the output Vsd of the toner density sensor 35 is less than the permissible value DELTAV of the slice voltage Vt, the current control voltage Vcd is inputted to a memory 14 to obtain the control voltage Vcd for adjusting the toner density sensor 35. |
