Brother PT 1000 - P-Touch 1000 B/W Thermal Transfer Printer, Service Manual

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II - 1
CHAPTER II THEORY OF OPERATION
2.1 Outline of Mechanisms
2.1.1 Print Mechanism
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Structure of Thermal Head
This machine uses direct thermal printing. The thermal print head has a heat generator
consisting of 64 heating elements which are vertically aligned in 180 dpi as shown in
Figure 2.1-1. Each heating element is 0.195 mm wide by 0.141 mm high.
Figure 2.1-1 Heat Generator of Thermal Head
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Printing Process
When the cylindrical rubber platen is pressed against the thermal print head with the tape
and ink ribbon sandwiched inbetween, the CPU applies current to the selected ones out of
the 64 heating elements.
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 graphic
pattern on the tape.
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Graphic Pattern Formation
While the drive motor (DC motor) feeds the tape and ink ribbon by 0.141 mm for 14.1 ms,
the thermal head generates heat once. The feed amount of 0.141 mm is smaller than the
width (0.195 mm) of the heating elements so that the heat generated at one heating cycle
will overlap with the next heating cycle. This forms a graphic pattern having no gap
between adjacent printed dots.