Brother PT-H100 Service Manual page 16

■ Ink Ribbon Feeding
As the DC 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
DC motor
Tape idle gear
Platen roller
Roller holder ASSY
Figure 2.1-9 Ribbon Feeding Mechanism
II - 7
Ink ribbon
Thermal head ASSY
Frame ASSY
Ribbon drive cam
Platen idle gear