n Scanning Lamp ON Pre-Heating Control (during copying operation I)Figure 4-1085. Controlling the Intensity of the Scanning Lamp (FL1)• If the intensity of the fluorescent lamp is too low at power-on,The starting power of the intensity adjustment sensor lowers, and the fluorescent lampintensity adjustment signal (FLS) of the amplifier circuit on the DC controller increases.In response to the signal, the microprocessor (Q512) on the composite power supplyPCB reduces the duty ratio, thereby increasing the ON time of the FLON signal.The current flows through the filament of the fluorescent lamp when both the MPWMsignal (150 kHz) and the FLON signal (1 kHz) are on.• If the intensity of the fluorescent lamp is too high at power-on,The starting power of the intensity adjustment sensor rises, and the fluorescent lampintensity adjustment signal (FLS) of the amplifier circuit on the DC controller PCBdecreases. In response to the signal, the microprocessor (Q512) on the compositePCB increases the duty ratio, thereby decreasing the ON time of the FLON signal.Caution:Gain Adjustment for the Intensity Adjustment Sensor (VR301)If you replaced the intensity adjustment sensor or the scanning lamp (fluorescentlamp, FL1), or the DC controller PCB, you must always perform gain adjustment forthe intensity adjustment sensor using VR301 on the DC controller PCB. (See the p.10-10.)COPYRIGHT © 1997 CANON INC. CANON NP6218 REV. 0 MAY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)CHAPTER 4 IMAGE FORMATION SYSTEM4-7FLON signalFLPRHT signalON ON5KHz1KHz5V0V44.4%OFF OFF40% or more
