Carriage Motor Controller/Driver Circuit - Epson DLQ-3000 Service Manual

Operating Principles

2.3.8 Carriage Motor Controller/Driver Circuit

The carriage motor is a hybrid type stepping motor which is driven with 1-2 phase or 2-2 phase
excitation in proportion to the desired rotational speed. This motor can be rotated in both
directions and stopped at any position. Four phase signals are directly output from the CPU and
pass through driver IC SLA7026M (ICI).
There are 10 speed modes which correspond to the desired printing speed. Beside these, there is
also a hold mode.
When the speed mode is changed, the current setting for the SLA7026M (ICI) motor driver is
changed. This enables it to supply the motor with the proper current for the speed mode setting.
The PFA and PFB terminals of the SLA7026M (ICI) ports are used to set the reference voltage for
the built-in chopping controller. The voltage is set at the output voltage level of the drive current
switching circuit.
The drive current switching signals (which set the voltage level between the PFA and PFB
terminals of the SLA7026M (IC1)) are output from general ports of gate array E05A88 (IC1l).
This circuit is also equipped with a drive voltage cut-off circuit. If an error occurs, there maybe a
condition in which the carriage motor energizing cannot be terminated, or an instantaneous
over-current may be supplied to the carnage motor. In such cases, some elements could be
damaged and faulty operation could occur. This is the reason for the drive voltage cut-off circuit.
When an error is detected, the all CPU ports are set HIGH, and all current setting ports of E05A88
motor driver to LOW. This cuts off the ~arnage motor energizing.
Table 2-25 gives the carnage motor controller/driver circuit specifications.
Table 2-25. Carriage Motor Controller / Driver Circuit Specifications
Source Voltage
Drive Method
CR speed x 4
Drive
Frequency —
Excitation 2-2
Method phase phase phase phase phase
Drive Current
Accelerating
Constant 2.5
2.0
speed /
decelerating
(A/phase)
2-24
35 VDC t 10%
Chopper constant current drive, 1-2/2-2 phase excitation
x 3 x 2 x 3/2
4320 2880 4320
2-2 2-2 1-2
2.0 2.0
1.5 1.5
x 3/4
x 4/3 x l
3640 2860 2160
1-2 1-2 1-2
phase phase phase phase phase
1.0 1.0
1.5
1.0 1.0 0.6
x 2/3 x 112 x 1/3 ~••ˆøRy•ˆ••ˆ••x•€Ö`••
1920 1440 960
1-2 1-2 1-2
1.0
0.6 0.6 0.6