| 摘要 |
PURPOSE:To enable exact detection of a toner with high precision, by optically detecting concentration of the toner attached to a conductive rotary body same in voltage as development bias voltage applied to a magnet roller forming a magnetic brush. CONSTITUTION:Bias voltage is applied to rotary conductive disk 22, rotating adjacently to magnet roller 14 forming magnetic bursh 15, from bias voltage source 16 also applying the same bias voltage to roller 14 in order to keep disk 22 and roller 14 in the same potential. This structure permits always stable toner attachment characteristics to be ensured by disk 22 without enlarging the capacity of source 16 and independent of resistance of a developer, and high precision exact detection of developer concentration to be carried out with optical detector 26. |
