- HP Printer User Manual

68 MFP unit explanation ENWW
Gradation correction control must be
performed in two ways: 1-dot PWM (for
normal mode) and 2-dot PWM (for
photo mode).
b Timing
1 When the fuser temperature is lower
than 50° C at SW2 (sub power) on
2 Every 5,000 prints, upon completion
of the last job.
2 Signals
a Input signals
1 G_SIG_EX (TCSB to PRCB)
This signal monitors the output
voltage from the γ sensor (PD2) on
the TCSB (toner control sensor
board) as well as the light reflected by
the drum surface (without toner).
The voltage applied to the gradation
detection LED is corrected by
TNLED_REF so that the output
voltage becomes 3.0 V (calibration).
Reference voltage: 3.0 V
<Timing>
Before gradation correction.
b Output signal
1 γ LED CONT (PRCB to TCSB)
Gradation detection LED ON/OFF
control signal
[L]: LED on
[H]: LED off
Dot diameter correction control
Dot diameter is detected by TCSB (toner
control sensor board) and is controlled by
PRCB (printer control board).
1 Operation
Dot diameter correction is performed to
prevent the 1-dot laser beam diameter
from fluctuating due to the change in
developing characteristics (caused by
deteriorated developer) and soil in the
laser scanner unit.
a Method
Multiple dot pattern patches with the
same condensation are created to be
read by the γ sensor (PD2). The laser
power where the γ sensor output
reaches the reference voltage is used
as the MPC value.
b Timing
1 Every 10,000 prints, upon completion
of the last job.
PRCB
TCSB
DCPS
12V2
S.GND
12V
A.GND
G SIG EX
LED CONT
TNLED REF