JPS54153037A - Developing power control device of two color developer - Google Patents

Abstract

PURPOSE:To readily and accurately control respective developing powers of two color toners by alternately and periodically applying voltages of different polarities between electrode plates and a fine wire electrode and respectively measuring the toner quantitites deposited. CONSTITUTION:When the negative pole of a DC power source 13 is connected to a fine wire electrode 11 and the positive pole to electrode plates 5, 6 via ground and the polarities of the voltages having been applied to the electrodes are inverted by a switch 12, the red toner of two color developers 19 having deposited on the electrode plates 5, 6 repulse to the electrode plates and detach therefrom because of a reverse electric field, thus falling down together with the flowing-down developer particles. In addition, the black toner having charged negative out of the subsequent developers deposits on the electrode plates 5, 6 in place of the red toner. In this way the developing powers may be radily and accurately controlled by measuring the respective toner quantities having deposited on both electrode plates with the light emitting element 8 and photo detector 10 provided to a developer guide tube 4, comparing these with the reference signals for the respective toners by a comparing operational amplifier 15, detecting the deviations from the reference values and replenishing the necessary qunatities of the respective toners.