| 摘要 |
PURPOSE:To make it possible to directly detect the effective developing capability by providing a pair of toner catching electrode plates and a cleaning electrode wire in the passage of a developing agnet so that an AC voltage and a DC voltage at a toner attracting polarity are alternately and periodically applied. CONSTITUTION:A pair of toner catching transparent electrode plates 7 and 8 facing each other across the passage 5 of a developing agent, a complementary filter 10a of the color of the toner, a light emitting element 10 and a photoelectric element 11 are used to measure the quantity of the toner caught by the electrode plates 7 and 8. A toner cleaning electrode wire 9 is arranged on the center line of the passage 5. Switches 14 and 16 are alternately driven to alternately and periodically apply an AC voltage and a DC voltage at the toner attracting polarity to the electrode plates 7 ans 8 and the electrode wire 9. Thus, the output signals of the element 11 are pulsated between the output levels under the cleaning condition and under the toner cathing condition, and the amplitude of fluctuations of the two output levels indicate the value corresponding to the correct developing capability from which the cleaning level is eliminated. |
