Thread Cutter - Brother NX600 Service Manual

Outline of Mechanism Pattern generator and thread cutter
Pattern generator
Conventionally, a cam that has the mechanical data cut into it has been used to move the adjuster and needle bar and
generate the pattern. However, this sewing machine operates an F pulse motor and Z pulse motor, moves the feed
adjuster and needle bar and generates the pattern using data (532 types) stored in internal CPU memory.

Thread cutter

Conventionally, the thread cutter mechanism has been driven by the rotation of the lower shaft. However, in this
machine, the thread cutter mechanism is driven by the rotation of an independent pulse motor to make for greater
accuracy in thread feed.
Since high positioning precision and response speed are required of the pulse motor, a PM pulse motor is used, and a
simple open loop circuit configuration is used.
Pattern generator control block diagram
Pattern selecting switch
(PCB ASSY:OPERATION)
Thread cutter switch
(PCB ASSY:SS-VR)
Z drive circuit
Pattern
F drive circuit
data
C drive circuit
S drive circuit
Needle bar
mechanism
Needle bar release
mechanism
Feed adjustment
mechanism
Thread cutting
mechanism
Side feed
mechanism
1 - 7