3. OPERATION AND TIMINGCOPYRIGHT © 2001 CANON INC. CANON CLC1000/1000S/3100 REV.2 MAY 2001 PRINTED IN JAPAN (IMPRIME AU JAPON)3-32C. Scanner Motor1. OutlineFigure 3-205 shows the circuit used to control the scanner motor, and the circuit has the followingfunctions:1 Controls the direction of rotation of the scanner motor.2 Controls the speed of rotation of the scanner motor.The scanner motor changes its direction of rotation between when the scanner moves forward andwhen it moves in reverse, and its speed of rotation varies according to the selected reproduction ratio.Its speed of rotation when the scanner is moved in reverse is the same regardless of the selectedreproduction ratio. It rotates about 10 times as fast as when the scanner is moved forward in Direct.Figure 3-2052. OperationThe CPU (Q651) on the scanner motor driver PCB receives mode, distance, and reproduction data fromthe image processor PCB. Then, in response to the start command, it sends drive pulses to the scannermotor to suit these data units. The scanner motor is a 5-phase stepping motor; the direction and the speed ofscanning are varied by changing the order of the drive pulses (A through E) and the frequency.To rotate the motor at a high speed when the scanner is moved in reverse, the drive voltage switchingcircuit switches the power used to drive the motor from 8 V (forward) to 24 V (reverse).The constant current control circuit controls the current flowing to the motor to a constant current to suitthe speed of rotation.The circuit cuts the current to the motor by the HOLD-OFF signal while the motor remains at rest duringstandby to prevent heating of the motor.Q651Voltage switching Drive voltageswitching circuitConstant currentcontrol circuitCurrent switchingScanner motor driver PCBScanner motor (M29)Reader controller PCBCurrentdetectionHOLD-OFFA~E+24V +8V24Vor8V4ABCDEA~E Motor drivercircuitMicroprocessor
