Table of Contents
Advertisement
B. Motor control circuit
[a] Paper feed motor (DFM) speed control circuit
S20
DFMRS
+5V
12
14
C56
R86
15
17
This circuit maintains the motor rotation at constant, and controls power supply to the paper feed motor so that the paper feed motor rotation sensor
frequency coincides with the clock signal frequency.
This circuit is composed of the following four blocks:
(A) Reference clock switch circuit
(B) PLL circuit
(C) PWM circuit
(D) Overshoot prevention circuit
As the basic operations, the frequency difference and the phase difference of the paper feed motor rotation signal and the reference clock are
converted into a voltage by the IC9 and PWM-modulated to synchronize the motor speed.
When rising to the low speed, the duty ratio of the PWM signal is forcibly limited to minimize overshoot of rotating speed.
TP67
VDD-+5V
+5V
2
3
Fref
Fsig
7
19
R93
FGin
DO
5
8
R125
LW
APC
9
R124
R/S
AFC
10
C
Vro
13
D6
LD
IC9
11
R137
RL
RV
18
RM
VC
16
C38
4
R42
NC
Test
6
NC
ZD 8
+5V
C45
TP24
TP25
R139
R65
5
C54
+
7
6
C51
-
+
R136
IC5-1
+
R138
Motor control circuit
– 27 –
VCC-DC+24V
GND-GND
5
+5V
Ct
IC8
6
10
Rt
E2
15
11
CL-
R141
C2
16
TP41
CL+
9
2
E1
EA-
1
8
13
12
61
EA +
C1
3
14
Fead
Ref
IC12.6
4
13
Dead
OC
R33
R34
TP40
R92
21
C37
M1PWM
PWM8
Advertisement
Table of Contents
