Toner Density Control - Ricoh FT7770 Service Manual

5. Toner Density Control

The CPU checks toner density by directly sensing the image density at the
end of the first copy cycle after the main switch turns on, and at every
fifth copy after that.
On check cycles, a black sensor pattern is exposed after exposure of the
original on the glass.
located under the right scale.)
reflectivity is checked by the image density sensor (photosensor).
If the reflectivity of the developed pattern is too strong, it indicates that
the toner density is too low. When this condition exists, the CPU energizes
the toner supply clutch to add toner to the development unit.
The toner is not all added at one time. The CPU energizes the toner supply
clutch long enough to add a selected amount of toner over the next five
copy cycles.
(This sensor pattern is mounted on a bracket that is
After this sensor pattern is developed, its
2-29
30
April, '89