Stepping Motor Drive Circuit - Panasonic KX-FT21BX Service Manual

4-4. STEPPING MOTOR DRIVE CIRCUIT

(1) Function
One individual stepping motor is used for transmission and reception. It feeds the document or recording paper
synchronized for reading or printing.
(2) Circuit Operation
During motor drive, gate array IC1 pin 153 becomes a high level, and Q14 and Q7 go ON as a result. +24 V is supplied to
the motor coil.
Stepping pulses are output from gate array IC1, causing driver IC7 to go ON. The motor coil is energized sequentially in
2 phase increments or 1-2 phase increments, which causes a 1-step rotation. A 1-step rotation is 0.13mm of recording
paper or document paper.
The timing chart is below.
Timing Chart (2 Phase)
T2
T3
T4
T5
Circuit Diagram
GATE ARRAY
IC4
T0 153
152 6
T2
151 5
T3
150 4
T4
149 3
T5
When the motor is OFF, gate array IC1 pin 153 becomes a low level and Q14 and Q7 also turns OFF. Instead of +24V, +5V
is supplied through D2 so that the motor is held in place.
Function
Copy
FAX
+24V
R63
R64
Q7
Q14
IC7
D4 D3
9
11
12
13
14
Stepping Motor Phase Pattern
Mode
Fine/Half Tone
Super Fine
STD
Fine/Half Tone
Super Fine
Paper Feed
1-2. Phase (Asic T2-T5, output)
T2
T3
+5V
T4
T5
D2
CN3
4
(RECEPTION)
5
TRANSMISSION
MOTOR
3
2
1
- 125 -
KX-FT21LA
Drive Phase
Speed
Pattern
1-2 217 pps
1-2 108.5 pps
2 217 pps
1-2 217 pps
1-2 108.5 pps
1-2 434 pps