Specifications

6. TONER DENSITY DETECTION AND TONER
SUPPLY
6.1 DETECT SUPPLY MODE
The CPU checks toner density by directly sensing the image density every 10
copy cycles (every 5 copies for the color development unit). If the RAM is
cleared (SP mode #99), or a new RAM is installed, the CPU checks the
image density at the beginning of the first copy cycle.
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 (a photosensor). The CPU notes the reflectivity.
If the reflected light is too strong, indicating a too low toner density condition,
toner is added to the development unit.
The toner is not added all at once. The CPU energizes the toner supply
clutch solenoid for the proper amount of time to add a selected amount of
toner over the next 10 cycles.
When a color development unit is used, the CPU automatically selects fixed
toner supply mode.
Development
Bias
ID Sensor
Pattern
1234567891011121314 202122
Toner Density Detection Toner Density Detection Toner Density
Detection
RAM Clear
Low Toner Density
Toner Supply Timing
Toner Add
Toner Supply Clutch ON
(10 times)
Detection
Detection
1st
2nd 3rd
Sensor
Pattern
Original Lead Edge
Original
Leading Edge Erase
A B C
D E
ON OFF ON OFF
1 December 1990
2-35