Epson FX-870/1170 User Manual download pdf (Page 142)

Principles of Operation

Carriage Motor Drive Circuit

The carriage motor drive circuit controls the CR motor. An open loop, constant-current drive

arrangement runs the

CRmotor.

2-2 and 1-2 phases are used to excite the motor. A 2-2 phase step

is equivalent to a 1-2 phase step doubled. Table 6-6 describes the motor drive modes.

The CR motor drive circuit of the SLA7024M (IC6) detects and regulates the amount of current

flowing in the carriage motor coil. The current flowing through the coil varies, depending on the

speed of the CR motor. The CPU sets the amount of current via the I/O port of the gate array.

Signals are sent to the ports (L, M, HOLD) on the

SLA7024M.

The

SLA7024M

sets the coil current

depending on the CR motor speed.

The printer may stop printing to protect the CR motor from overheating if a continuous printing

of short columns (less than 10 columns) is repeated. The printer uses CPU ports

P60

to P63

exclusively to control the CR motor.

CPU

(IC2Cl)

P60

P61

P62

P63

SLA7024M

(IC6)

CR MOTOR

ASSEMBLY

4-phase,

200-p,

HB-type

pulse

motor

5.4

10%

(per

phase)

(at

77”

25°C)

Speed Mode

413

910

516

2l3

l/2

5/l

l/4

5124

Figure 6-27. Carriage Motor Drive Circuit

Table 6-6. Carriage Motor Drive Modes

PPS

4468

2-2

3840 2-2

3357 2-2

2800

2-2

2240

2-2

1680 1-2

1400

l-2

840

l-2

700

l-2

420

-2

Excitation Phase

Characters Printed

Super draft

Super draft copy

Draft 10 cpi

4/3

high duty

NLQ

5/12

high duty

l/4

high duty

6-27

Epson

FX-870/1170

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Epson FX-870/1170 User Manual Page 142

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