Brother PC-3000 Service Manual download pdf (Page 8)

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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

7. AUTOMATIC THREAD TENSION BLOCK DIAGRAM

1 2 3 4 5 6 7 8 9 10 11 12 13 ... 66 67

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Brother PC-3000 Service Manual Page 8