2. Turning On and Off the Scanning LampThe microprocessor (Q301) on the DC controller PCB exerts control so that themicroprocessor (Q512) on the composite power supply PCB generates the scanninglamp ON signal (FLON)=0 (pulse signal, 1 kHz). At the time, the fluorescent lamp drivecircuit applies the output of the secondary side of the transformer (T101) to the scanninglamp (FL1), thereby allowing current to flow through the scanning lamp and causing thelamp 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 DCcontroller 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-heatcircuit. Based on the signal, the scanning lamp pre-heat circuit modulates the amplitudeof the signal (32 kHz); in response, the secondary side of the transformer (T401) turnson to allow the fluorescent lamp pre-heat current to flow, thereby starting pre-heatingoperation. (For the sequence of operations, see Figure 4-105.)4. Sequence of Operations (scanning lamp pre-heating control; AE, A4,continuous, 2 copies)1 half pre-heating control.2 full pre-heating control.3 ON pre-heating I or II control.Figure 4-105COPYRIGHT © 1997 CANON INC. CANON NP6218 REV. 0 MAY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)CHAPTER 4 IMAGE FORMATION SYSTEM4-5 STBYPower switchONCopy Start keyONAER *1*3 *3*2*1*1 *2INTR SCFW SCRV SCFW SCRV LSTR STBYScannerScanning lampPrimary charging1.5 sec
