Brother PT-D600 Service Manual page 18

 Ink Ribbon Feeding
As the stepping motor rotates, the ribbon drive cam located at the middle of the gear
train rotates counterclockwise. When fitted on the ribbon drive cam, the ribbon take-
up roll in the tape cassette also rotates to take up the ink ribbon.
To apply proper tension to the ink ribbon between the platen and the ribbon drive cam,
the feed amount of the ribbon drive cam is slightly greater than that of the tape idle
gear. The difference between the feed speeds at the platen roller and at the ribbon
drive cam is absorbed by the clutch spring which is integrated in the ribbon drive cam
and allows the cam to slip.
This way, the ink ribbon is kept tense, which enables the ribbon to clearly separate
from the tape at the stabilized angle after printing.
Tape feed roller built
in a tape cassette
(Tape idle gear)
Tape feed sub roller
Platen roller
Tape idle gear
Platen idle gear
Frame ASSY
Figure 2.1-7 Ribbon Feeding Mechanism
II - 7
Ink ribbon
Roller holder ASSY
Ribbon drive cam
Stepping motor
Thermal head ASSY