Chapter Ii Mechanism; Theory Of Operation; Print Mechanism - Brother P-touch PT-1180 Service Manual

CHAPTER II
2.1

THEORY OF OPERATION

2.1.1

Print Mechanism

(1) Structure of Thermal Head
This machine uses thermal transfer printing. The thermal print head has a heat generator
consisting of 64 heating elements which are vertically aligned as shown in Fig. 2.1-1.
Each heating element is 0.195 mm wide by 0.141 mm high.
(2) Printing process
When the cylindrical rubber platen roller is pressed against the thermal print head with the
tape* and ink ribbon sandwiched inbetween, the CPU applies electric power to the selected
ones of those 64 heating elements.
* Laminated tape when using laminated tape cassettes.
Non-laminated tape when using non-laminated cassettes.
[For tape cassette except non-laminated thermal film tape cassettes]
If the selected heating element(s) generates heat, the ink on the sandwiched ribbon will be
melted and transferred to the tape, producing a dot(s) on the tape. The ink ribbon and the
tape are advanced and then the next heating cycle is repeated, thus forming a character on
the tape.
[For non-laminated thermal film tape cassettes]
If the selected heating element(s) generates heat, the thermal film tape develops itself to
produce a dot on the tape. The tape is advanced and the next heating cycle is repeated,
thus froming a character on the tape.
(3) Character Formation
While the drive motor (DC motor) feeds the tape and ink ribbon by 0.141 mm for approx
14.0 ms, the thermal head generates heat once. The feed amount of 0.141 mm is smaller
than the
heating cycle will overlap with the next heating cycle. This forms a character having no gap
between adjacent printed dots.
MECHANISM
Fig. 2.1-1 Heat Generator of Thermal Head
width (0.195 mm) of the heating elements so that the heat generated at one
II-1