CANON NP6021
Service Manual

I

OPERATIONS

AND TIMING

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Input Signals from the DC Controller PCE to the Composite Power Supply PCB Half pre- Fullpre- Fluorescent Fluorescent heating heating lamp I� lampONII� ON

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Scanning Lamp ON PreiHeating (copying operation I)

Control

I IN.1

II
/
FLON signal ON ON
OFF

:??%cT!? r

OFF

Filament 2.5vrms 4.5vrms 3.6Vrms 4.1Vrms voltage *ON Duty Ratio (against 1 KHz) of the FLON signal: ON I control if 40% or more; ON II if less than 40%.
FLPRHT signal

j

LS_?HZ ;1/44.4%

Figure 3-307 Table 3-301 fl Half Pre-Heating Control (between power-on and Copy Start key-on; pan of scanner reverse movement)
OFF FLON signal 5KHz :..........I

5. Controlling
l

the Intensity Scanning Lamp (FLl)

of the

If the intensity is low when the scanning lamp turns on, The start-up power of the adjustment sensor decreases and the fluorescent lamp adjustment signal (FLS) of the amplifier circuit on the DC controller PCB increases. Using this signal, the microprocessor (U402) on the composite power supply PCB decreases the duty ratio, thereby increasing the ON period of the FLON signal. Current flows to the filament of the fluorescent lamp when both MPWM signal (150 KHz) and FLON signal (1 KHz) are ON.

Figure 3-305
l

n Full Pre-Heating Control (initial rotation, last rotation; part of scanner reverse movement)
OFF FLON signal

If the intensity of the fluorescent lamp is high when the fluorescent lamp turns ON, The start-up power of the adjustment sensor increases, and the fluorescent lamp signal (FLS) of the amplifier circuit on the DC controller PCB decreases. Using this signal, the microprocessor (U402) on the composite power supply PCB increases the duty ratio, thereby decreasing the ON period of the FLON signal.

; 5KHz r---------1 FLPRHTsig�p, f)-l r-y; 1:

Figure 3-306

3-40

COPVRI6WT01986 CANONINC.

CANON NPA521REV.lOEC.1996 PfUNTEOIN.lAPAN(IMPfUMEAUJAWN)