Ricoh Robin Service Manual page 20

24 June 1994
1. DRUM
1.1 DRUM CHARACTERISTICS
An organic photoconductor (OPC) drum is used in this model.
The OPC drum has the characteristics of:
1. Being able to accept a high negative electrical charge in the dark. (The
electrical resistance of a photoconductor is high in the absence of light.)
2. Dissipating the electrical charge when exposed to light. (Exposure to light
greatly increases the conductivity of a photoconductor.)
3. Dissipating an amount of charge in direct proportion to the intensity of the
light. That is, where stronger light is directed to the photoconductor
surface, a smaller voltage remains on the drum.
4. Being less sensitive to changes in temperature (when compared to
selenium F type drums).
5. During the drum's life, drum residual voltage gradually increases and the
photoconductive surface becomes worn.
Therefore, some compensation for these characteristics is required.
2-1
DRUM