| 摘要 |
PURPOSE: To detect the reduction in specular reflectivity due to the application of toner grains by providing the desitometer with a means for projecting light rays to development grains on a photoconductive member and a means for generating a signal proportional to a total reflectivity, a signal proportional to a diffused component and a signal proportional to a mirror surface component. CONSTITUTION: Light rays generated from the light ray projecting means 102 are reflected from toner grains stuck to a photoconductive surface and an exposed part on the photoconductive surface and totally reflected light rays are received by a center photo-diode 126. Only a diffused component out of the reflected light rays is received by edge photodiodes 128, 130 to be detection means and generated electric signals are proportional only to the diffused component out of the reflected light rays. When the composite electric signal of these generated electric signals is subtracted from an electric signal generated from the diode 126, a voltage output V from a differential amplifier 132 is proportional only to a specular component out of a current output. Consequently the measurement value of an area coated with color toner grains stuck to the photoconductive surface is obtained. |
