Canon NP6085 Service Manual page 104

3. OPERATIONS AND TIMING
The rotation speed control circuit compares
the scanner speed signal and the clock pulses
(M2CLK) 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/OFF the power to the motor at short intervals
(while keeping the voltage constant), thereby con-
trolling the speed by varying the intervals.
The DC controller PCB generates the repro-
duction ratio selection signal (M2MD0, 1, 2) as
shown in Table 3-203 to change the speed of
scanner motor according to the selected repro-
duction ratio.
Copy Start key ON
Scanner motor drive
signal (M2ON)
Scanner forward signal
(M2F/R)
Scanner speed control
signal (M2FS)
Scanner stop signal
(M2BRK)
Scanner home position
sensor (Q5)
Scanner original leading
edge 1 sensor (Q4)
3-46
COPYRIGHT © 1996 CANON INC.
M2
MD2
0
0
0
0
1
1
1
1
INTR SCFW
Figure 3-216
CANON NP6085 REV.0 JULY 1996 PRINTED IN JAPAN (IMPRIME AU JAPON)
DC
M2 M2
controller
MD1 MD0
PCB driver PCB
0 0
200%~
0 1
172%
171%~
1 0
151%
150%~
1 1
91%
92%~
0 0
72%
71%~
0 1
68%
67%~
1 0
64%
1 1 Motor drive circuit
Table 3-203
SCRV
*1
*2
*1 Scanner slow-down braking
*2 Scanner stop braking
Scanner
Motor stop
motor
circuit
64%~
62%
61%~
50%
LSTR