Canon NP6045 Service Manual page 88

CHAPTER 3 EXPOSURE SYSTEM
The rotation speed control circuit compares the scanner speed signal and the clock
pulse (SCMCLK) generated by the scanner motor and sends control signals to the motor
drive circuit according to the difference.
The motor drive circuit does not change the voltage applied to the motor but rather
turns ON and OFF the power to the motor at short intervals to control the speed of
rotation. (The voltage is maintained constant, but the ON/OFF periods are varied.)
Since the rotation speed of the scanner motor must be varied to suit the selected
reproduction ratio, the reproduction ratio selection signal (M3MD0, 1, 2) is generated by
the DC controller PCB as shown in Table 3-303.
Scanner motor drive signal
Scanner forward signal
Scanner speed
control signal
Scanner stop signal
Scanner home
position sensor
Scanner original leading
edge 1 sensor
3-12
COPYRIGHT © 1997 CANON INC.
M3MD2 M3MD1
0 0
0 0
0 1
0 1
1 0
1 0
1 1
1 1
Table 3-303
Copy Start key ON
INTR
Figure 3-305
M3MD0 One-sidey copy
0 204~172
1 171~144
0 143~120
1 119~100
0 99~79
1 78~62
0 61~49
1 Scanner reverse
movement
SCFW SCRV
*1:Scanner slow-down braking.
*2:Scanner stop braking.
CANON NP6045 REV. 1 MAR. 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)
LSTR
*1
*2