Specifications

7-2. AIDC Sensor
To provide image stabilization control, this copier has AIDC Sensor UN9
fitted to the Cleaning Unit of the PC Unit. The sensor is used to detect the
toner density and background level on the PC Drum.
Theory of Operation
1. The UN9’s LED projects approx. 940-nm infrared light onto the surface
of the PC Drum.
2. The UN9’s phototransistor detects the amount of light reflected back.
3. The phototransistor outputs a voltage corresponding to the intensity of
the light reflected back.
PC Drum Surface
Output GND LED Power Supply
Toner Density Reflected Light Output
High Small High
Low Large Low
The AIDC Sensor LED is turned ON or OFF by the pulse signal output from
pin 13 of IC1A on Master Board PWB-A. The intensity of the light emitted by
the LED is controlled by varying the pulse width as shown below.
IC1A-13
1075T184CA
OFF ON ON ON ONOFF OFF
Pulse Width
AIDC Sensor
LED
Light Amount : Small Light Amount : Large
M-18