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PRINCIPLES OF OPERATION
2-2. Data Arrangement and Printing
2-2-1. Arrangement
The CPU reads data sequentially from RAM and arranges this data in accordance with program instructions stored in
EPROM. The arranged data is then converted from parallel to serial form. The gate array then outputs the resulting serial
data to the drive controller in the thermal printhead.
2-2-2. Thermal printhead
The thermal printhead has 576 heat elements. Printing is executed by switching these elements ON and OFF as required.
The printhead contains a built-in dedicated drive controller. The controller consists of shift register, latch circuit, and
driver circuit, as illustrated below. The controller receives serial data (SI) from the gate array in sync with the CLK signal.
It latches this incoming data (by LATCH signal), then outputs the data to the elements in sync with the falling edge of
the STROBE signal. A data value of LOW corresponds to an element value of ON (generating print).
Fig. 2-4 Drive Circuitry of Thermal Printhead
B. E. O
LATCH
CLOCK
STROBE4
STROBE3
STROBE2
STROBE1
V
H
DATE IN
(SI)
SO
R576 R1
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