Panasonic DP-CL18 Technical Manual page 35

3.5.10. Color Registration Sensor Circuit
This circuit is for reading the color registration check pattern generated on the accumulator belt by software and IC1 (CPU) receives
this information through IC8 and IC14. IC1 (CPU) controls the charge bias, development bias, toner supply bias, first transfer bias
(FTR), reverse bias to performing a fine color adjustment.
This circuit has 2 sensors: left color registration sensor and right color registration sensor. The signals LED-L and LED-R are the
light emitting signal. The SEN-L and SEN-R are the output signal from the photo transistors in the left and right color registration
sensors. These signals are inputted to IC14 (signals REG1, REG2) through IC8 and IC9 [to IC1 (signals AREG1, AREG2) through
IC8].
The current that flows in the LEDs of color registration sensors are controlled by the duty of signals REGLED1 (pin120) and
REGLED2 (pin118). When the duty is enlarged, the current is increased. This increases the light form the LED, and the voltages
of signals AREG1 & AREG2 raise because the reflected light from the accumulator belt increases. At the power on, IC1 (CPU)
receives the signals AREG1 & AREG2 that are created by directly reflected light from the surface of accumulator belt. If this signals
are 2.5V or less, IC1 (CPU) raises the voltages of these signals to 3.0 ± 0.1V by enlarging the duty of signals REGLED1 (pin120)
& REGLED2 (pin118). At this sensing condition, the voltages of signals AREG1 and AREG2 are 1.5 ~ 2V when sensing the color
registration detection pattern. If each of theses signals is 2.5V or more, the error message "Printer Error 56" is displayed.
The signals AREG1 and AREG2 are changed from the analog signal to the digital signal by the comparator IC9 and are inputted
to IC14. IC14 compares these digital signals with the predetermined pulse number by the internal counter. These sensing is called
"Color Registration Sensing"
First color registration sensing is done at the power on and each 250 sheet printings thereafter.
Movement Direction of Accumulator Belt
Accumulator Belt
LED-L
LED-R
AREG1
(pin 89, IC1)
AREG2
(pin 90, IC1)
Approx.2 sec
Approx. 3V
AREG1, AREG2
Vref
(pins 2, 6: IC9)
REG1 (pin 110, IC14)
REG2 (pin 116, IC14)
Created Color Registration
Detection Pattern on accumulator belt
Approx.6.7 sec
2.5V
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DP-CL18