Ricoh FT5034 Service Manual page 64

2. Toner Density Control
Full Erase
[Low Toner]
Developed Sensor
Pattern Image
The main CPU checks toner density by directly detecting 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.
When the image density is too low, the CPU activates the toner supply clutch to add
a selected amount of toner over the next 10 copy cycles.
During image density detection cycles, the center block of the erase lamps turns off
(A5 Lengthwise size) long enough for the sensor pattern to be developed. When the
sensor pattern image on the drum is over the ID sensor, the LED of the ID sensor
turns on and the light reflected off the sensor pattern image is checked by the ID
sensor (which is a photosensor). While the sensor pattern is being developed, the
bias voltage is set at 470 volts.
Sensor Pattern
Full Erase
A5 Lengthwise
Low Toner
Image Density
Sensor
PTL
Original Lead Edge
Leading Edge Erase
[Enough Toner]
- 63 -
Original
Enough Toner