Ricoh FT4215, Service Training Manual

Page: 68 / 208

6.2 ID SENSOR FUNCTION IN DETECT SUPPLY MODE
The image density sensor checks the density of the sensor pattern image
once every 10 copy cycles. The CPU receives two voltage values directly
from the sensor: the value for the bare drum (Vsg) and the value for the
sensor pattern (Vsp). These two values are then compared to determine
whether more toner should be added.
1. Vsp
≤
1/8 Vsg ..... No toner is added. (High density)
2. Vsp > 1/8 Vsg .....Toner is added. (Low density)
When the image density is too low, the CPU activates the toner supply clutch
to add toner over the next 10 copy cycles. The amount of toner added
depends on the value of Vsp, the selected toner supply ratio (SP31), ID
sensor data and the paper size in use. (See page 2-43 for more information.)
When the data of SP35 is set to "1" (factory setting = "0"), the CPU changes
the interval of the ID check from every 10 copies to every 5 copies for the
black development unit.
ID Sensor LED
CN110-1
CN110-3
CN110-2
ID Sensor Output
TP 106
(PIN)
+5V
A
K
C
E
B
C
A
VR102
R
MC1
+24V
CN118-2
CN118-1
CPU
I/D Sensor
Main Board
Toner
Supply
CL
[BLACK]
Vsg 4V
Vsp
Low Density
High Density
(1/8 Vsg)
FT4220/4222 2-37 STM