Paper Feed Mechanism - Star Micronics NX-1020 Technical Manual

4-4. Paper Feed Mechanism

The paper feed motor is a PM (Permanent Magnet) type, four-phase and 48-pole pulse motor. Minimum paper feed is set
at 1/432 inch.
There are two ways of feeding paper available with this printer: Friction method and Tractor method. You can select one
of the two methods, using the release lever.
Position of release lever
Position of tractor
Tractor gear and tractor clutch
Holder roller position
Direction of rotation of tractor gear
Release lever position detector
Tractor position detector
Paper feed method
(1) Friction Method
Friction method is selected when the release lever is position [1]. With this method, paper is pressed between the
platen roller and the holder roller therefore, paper is fed as the rollers turn.
As the paper feed motor is driven, the motor gear, through the idler gear, turns the platen gear in the paper feeding
direction. However, since the tractor gear and the tractor clutch are not linked at this time, the tractor unit will not
be driven.
(2) Tractor Method
Tractor method is selected when the release lever is position [2] . Paper feeding is facilitated by rotation of the
sprocket pin of the tractor unit. When the tractor method is selected, the tractor gear is linked to the tractor cluch,
enabling the drive force generated by the paper feed motor to be transferred to the tractor unit via the idler gear and
the platen gear.
[1]
[A] (Down)
Not linked
Up
CW
Open
Closed
Friction
Fig. 2-23 Paper Feed Mechanism
– 35 –
THEORY OF OPERATION
[1] [2]
[B] (Up) [A] (Down)
Linked Linked
Up Down
CCW CW
Open Closed
Open Closed
(Error) Push tractor
[2]
[B] (Up)
Linked
Down
CCW
Closed
Open
Pull tractor