Main Motor Control; Pattern Generator - Brother PC8200 SUPER GALAXIE 2000 Service Manual

5.

MAIN MOTOR CONTROL

The main motor for the sewing machine is required to smoothly change from low speed to high speed without any
fluctuations due to load or temperature changes. To fully comply with this requirement, the Super Galaxie adopts
PWM control using FET.
6.

PATTERN GENERATOR

For conventional sewing machines, the pattern was generated by rocking the needle bar and the feed regulator by
means of a pattern cam onto which the pattern data had been mechanically engraved. In contrast to this, this model
stores the data electronically in memory and uses a feed pulse motor, horizontal pulse motor and a zigzag pulse
motor to directly rock the needle bar and the feed regulator to generate the pattern. As a result of this, it is possible to
increase the number of patterns and the number of stitches simply by adding extra memory capacity, so that about
3,800 patterns comprising a total of approximately 20,000 stitches can be stored. In addition, the pulse motors must
move the position of the needle while the needle is raised and stop it in the correct position (and similarly, they must
move the position of the feed regulator while the needle is lowered). Thus, highly-precise positioning and a fast
response speed are required. Because of this, the feed pulse motor, horizontal pulse motor and a zigzag pulse motor
were adopted, and a simple open-loop structure circuit structure was employed.
Block diagram of pattern generator control
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