Toner Density Detection And Toner Supply; Toner Density Detection - Ricoh FT4430 Service Manual

16 April '88
TONER DENSITY DETECTION AND TONER
SUPPLY

TONER DENSITY DETECTION

A
[Low Toner]
Developed Sensor
The main CPU checks toner density by directly sensing the image density at
the beginning of the first copy cycle after the main switch is turned on, and at
every 10th copy after that.
During the check cycles, the sensor pattern is exposed prior to exposure of
the original. After the sensor pattern is developed, its reflectivity is checked by
the image density sensor (which is a hotosensor). The CPU notes the
reflectivity. If the reflected light is too strong, indicating a too low toner density
condition, it adds toner to the development unit.
The toner is not added all at once. The CPU energizes the toner supply
solenoid for the proper amount of time to add a selected amount of toner
over the next 10 cycles.
Sensor Original Lead Edge
D E
B c
2-36
.
Edge Erase