Stepping Motor (Tape Feed Motor) Drive Circuit - Brother PT-9200DX Service Manual

3.2.4

Stepping Motor (Tape Feed Motor) Drive Circuit

Fig. 3.2-4 shows the stepping motor drive circuit.
The Ø25 stepping motor is used to feed the ribbon and the tape. The stepping
motor feeds the tape 1/720 in. for one pulse (one dot for two pulses).
Drive pulses are transmitted from P104-P107 of the CPU (#1) to Q1-Q4 to drive the
motor with a unipolar 2-2 phase excitation (AB DA CD BC forward feed).
(1) Printing at fixed speed
The rate of fixed speed printing, at which printing is performed while the tape is
fed at a fixed speed, is 571 pps (1.75 msec/pulse).
The through-up pulses (including pre-excitation) and through-down pulses
(including post-excitation) are 56 and 5 pulses, respectively.
(2) Halfway stop of printing
If printing is stopped halfway, the circuit continuously drives the motor (overrun
for 198 pulses) after the stop, then shuts off the power.
(3) Printing interruption (margin cutting drive, half cutting drive, and buffer full
drive)
a) At the interruption of printing, the motor overruns (five through-down
pulses) before it stops.
b) If cutter operation is necessary, full or half cutting is performed.
c) The motor rotates counterclockwise for 70 pulses.
d) The motor rotates clockwise to resume printing with 3 dots printed again.
Fig. 3.2-4 Stepping Motor Drive Circuit
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