CHAPTER 4 IMAGE FORMATION SYSTEM

2. Turning On and Off the Scanning Lamp

The microprocessor (Q301) on the DC controller PCB exerts control so that the microprocessor (Q512) on the composite power supply PCB generates the scanning lamp ON signal (FLON)=0 (pulse signal, 1 kHz). At the time, the fluorescent lamp drive circuit applies the output of the secondary side of the transformer (T101) to the scanning lamp (FL1), thereby allowing current to flow through the scanning lamp and causing the lamp to turn on at a high frequency (about 120 kHz).

3. Pre-Heating Control (scanning lamp)

The copier exerts four modes of control; namely, half pre-heating, full pre-heating, ON pre-heating I, and ON pre-heating II.

These modes of control are executed by the microprocessor (Q301) on the DC controller by varying the duty ratio of the fluorescent lamp pre-heat signal (FLPRHT; pulse) of 5 kHz to suit each pre-heat control mode sent to each scanning lamp pre-heat circuit. Based on the signal, the scanning lamp pre-heat circuit modulates the amplitude of the signal (32 kHz); in response, the secondary side of the transformer (T401) turns on to allow the fluorescent lamp pre-heat current to flow, thereby starting pre-heating operation. (For the sequence of operations, see Figure 4-105.)

4.Sequence of Operations (scanning lamp pre-heating control; AE, A4, continuous, 2 copies)

Power switch Copy Start key

ON

ON

STBY

INTR

Scanner

*1

*2 1.5sec

Scanning lamp

Primary charging

AER

SCFW

*3

SCRV

*1 *2

SCFW

*3

SCRV LSTR STBY

*1

1half pre-heating control.

2full pre-heating control.

3ON pre-heating I or II control.

Figure 4-105

COPYRIGHT © 1997 CANON INC.

CANON NP6218 REV. 0 MAY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)

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Canon FY8-13EX-000, NP6218 service manual Turning On and Off the Scanning Lamp, Pre-Heating Control scanning lamp