Cr Motor Drive Circuit - Epson LG1-1070 Service Manual

Appendix B

CR Motor Drive Circuit

Figure B-7 shows the CR motor drive circuit, which uses an open-loop, constant-
current drive control to drive the CR motor. The motor is driven with 2-2 phase
excitation and 1-2 phase excitation. The 2-2 phase excitation corresponds to two 1-2
phase excitation steps, so for each single step phase change of a 2-2 phase excitation
motor, the carriage
moves
phase excitation motor, the carriage moves l/240 inch.
The CR motor drive circuit of the STK-67128 detects the amount of current flow in
the CR motor coil and regulates it. The current flowing through the coil varies
depending on the speed of the CR motor. The amount of current is set by the CPU
via the E05A50 I/O port. Signals are sent to Vrefl or Vret2 on the STK-67128. The
SIX-67128 sets the coil current to correspond to the CR motor speed. Ports P60 to
P63 on the CPU are used exclusively as phase control ports for the stepping motor.
P62
Drive Mode Excitation Type
3 x speed 2-2 phase
2 x speed 2-2 phase
1.5 x speed
2-2 phase
l-2 phase
1 x speed l-2 phase
l-2 phase
l-2 phase
B-12
Figure B-7. CR Motor Drive Circuit
Table B-9. CR Motor Drive Modes
Type Drive Frequency
2695 pulses per second (pps)
1773 pps
1347 pps
1191 pps
1796 pps
1347 pps
119opps
698 pps
Standard Print Character
High speed LO
Draft (emphasized, condensed)
LQ
Epson LQ-570+/1 070+