3–4
COPYRIGHT
©
1998 CANON INC. CANON NP7161/NP7160 REV.0 AUG. 1998 PRINTED IN JAPAN (IMPRIME AU JAPON)

CHAPTER 3 EXPOSURE SYSTEM

2. Motor Control CircuitThe lens motor (M3) and the mirror motor (M4) are 4-phase stepping motors, and arecontrolled by the motor drive power supply signal (COM) and four drive pulse signals (A, B, A*,B*) generated by the DC controller PCB.The direction of rotation of the motor is switched by changing the timing at which the fourdrive pulse signals (A, B, A*, B*) are generated.The motor drive power supply signal (COM) is used to supply +24 V when rotating eachmotor. It is used to provide +5 V when the motors are at rest, thereby ensuring that the lens andthe No. 4/No. 5 mirror unit remain still against vibration.
-3
-5
-4
-2
-1
-3
-1
-2
-4
-5
J101
-A3
-A1
-A2
-A4
-A5
Lens motor
LNS_A
LNS_COM
LNS_A*
LNS_B
LNS_B*
J38
M3
-3
-5
-4
-2
-1
-3
-1
-2
-4
-5
J103
-A7
-A5
-A6
-A8
-A9
Mirror motor
MMR_A
MMR_COM
MMR_A*
MMR_B
MMR_B*
J39
M4
Lens
motor
drive
circuit
DC controller PCB
+5V
+24V
Mirror
motor
drive
circuit
IC119
(CPU)
+5V
+24V
Figure 3-202