Epson MX-80 Technical Manual page 27

(4) 8041
The LSI "8041" is called a "slave CPU." In the MX-80. this LSI produces the drive signals
for the two stepper motors; one to control the carriage assembly of the print head and
the other to control paper feeding. These two stepper motors are driven by two two-
phase excitation signals. The sequence of each phase for the carriage stepper motor is
shown in Fig. 2.9 and the same for the paper feed stepper motor, in Fig. 2.10.
Phase CPA-
Phase CRB"
Phase CRC-
Phase CRD-
Phase LFA'
Phase LFB
Phase LFD
Phase LFC
Fig. 2.9 Carriage Stepper Motor Drive Signals (Forward)
Fig. 2.10 Paper Feed Stepper Motor Drive Signals
As Shown in Figs. 2.9 and 2.10. the respective stepper motors are driven by two two-
phase excitation signals. However, the driving pulse width ti of the carriage stepper
motor differs depending on the type of character to be printed, as shown below.
(a) ti of carriage stepper motor
1) Approx. 2.08 msec (with normal and enlarged characters)
2) Approx. 4.16 msec (with condensed characters)
(b) t2 of paper feed stepper motor: Approx. 4.16 msec
In addition to the two stepper motor drive signals, the 8041 generates a control signal
which lowers the applied voltage of each stepper motor so that the motor is not exposed
to unwanted heat when it is not driven. Fig. 2.11 shows the 8041 and its peripheral
circuits.
REV. A 2-14