Brother PT-1800 Service Manual page 21

n Adhesive Base Tape Feeding (only for laminated tape cassettes)
A laminated tape cassette contains both a transparent laminate tape roll and a separate
adhesive base tape roll.
When a transparent laminate tape and an adhesive base tape pass through the contact
point (between the tape feed roller and tape feed sub roller), they are then bonded
together into a single, printed tape. The ink printed on the laminate tape is, therefore,
sealed up with the adhesive base tape.
n Ink Ribbon Feeding (except for non-laminated thermal film tape cassettes and stamp
tape cassettes)
As the drive 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 feed
gear. The difference between the tape feed speeds at the platen 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.
Figure 2.1-4 Ribbon Feeding Mechanism
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