Pattern Generator; Automatic Thread Tension - promelectroavtomat ULT2003D Service Manual

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
www.promelectroavtomat.ru
-6-