Toner Density Detection - Ricoh FT5540 Service Manual

31 August 1989

6.3 TONER DENSITY DETECTION

E: Full Erase
F: ID Check
G: Edge Erase (copy cycle)
H: Low Toner Condition
I: Enough Toner Condition
J: Sensor Pattern Image
The main CPU checks the image density of the sensor pattern at the beginning of the first
copy cycle (after the main switch is turned on) and at every tenth copy cycle.
Alter the sensor pattern [A] is developed, the image density sensor [B] (a photosensor)
checks its reflectivity. If the reflected light is too strong, the CPU determines that the toner
density is too low. It then adds toner to the development unit.
Toner is not added all at once. The CPU energizes the toner supply clutch to add a selected
amount of toner over the next 10 cycles.
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