Brother PT-1090 Service Manual page 12

The roller holder ASSY supports the platen roller and tape feed sub roller so that they
can move perpendicularly to the thermal head and tape feed roller built in a tape
cassette, respectively, as well as rotating freely.
Closing the cassette cover presses the platen roller perpendicularly against the
thermal head with the tape and ink ribbon sandwiched inbetween under a uniform
load by the upper and lower roller holder springs. At the same time, the platen gear
becomes engaged with the platen idle gear.
The tape feed sub roller is pressed perpendicularly against the tape feed roller built in
the tape cassette with the tape (and adhesive base paper when using laminate tape
cassettes) sandwiched inbetween under a uniform load by the upper and lower roller
holder springs. At the same time, the sub roller gear becomes engaged with the tape
idle gear.
Opening the cassette cover pulls out its holder cam so that the roller holder release
spring retracts the roller holder ASSY from the thermal head, providing you with
enough space to replace the tape cassette.
Adhesive base tape
Tape cassette
Platen idle gear
Tape feed roller built in
a tape cassette
(Tape idle gear)
Tape feed sub roller
Holder cam
(provided on the
cassette cover)
Platen roller gear
Sub roller gear
Tape feed sub roller
Figure 2.1-4 Roller Holder ASSY Setting & Retracting Mechanism
Shaft (Bottom cover)
Roller holder ASSY
Platen roller
A
Roller holder spring, lower
Roller holder release spring
Platen roller
II - 3
Laminate tape
Ink ribbon
Thermal head ASSY
Roller holder spring, upper