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12-02-2003
Page 2-14 of - 2-14 -
51
2.7 THERMAL HEAD CONTROL
Data Transfer to the Thermal Head
The PRN604-S transfers one dot line of data at 6 Mbps synchronized
with the CLOCK signal.
The data is transferred in order to the shift register inside the thermal
head from the left (when facing the paper feed direction).
The transferred data is then transferred by the head latch signal to the
latch register inside the thermal head. Turning on the head strobe
signal initiates printing of one dot line of data on the thermal paper.
2.7.1 Thermal Head Drive Operation
Generally, when the line thermal head is operating, the line is divided
into several blocks, which are activated one after another in succession.
For the line thermal head of the FTP604 printer mechanism, the line is
divided into 7 blocks called physical blocks, 216, 288 or 416 dots with
each. A strobe signal (/ST1 to /ST7) is allocated to each physical block
to activate it. To drive the head, physical blocks are activated in groups.
The group of physical blocks is called a logical block.
For the PRN604-S either dynamic division or fixed division can be
selected as the method of division for logical blocks. This selection is
made through a function. See settings for more information.
2.7.2 Peak power limitation
The PRN604-S counts the number of dots activated in each physical
block and groups the physical blocks into logical blocks to print a single
dot line so that the number does not exceed the specified maximum
number of activated dots. The PRN604-S determines logical blocks
each time it prints a single dot line.
In dynamic division, in order to avoid unclear printing, at the first step of
the motor the thermal head is driven and at the second step the paper
is fed.
Also, since the order of the printing blocks and printing speed are
changed in each dot line according to the content of the print data, print
quality may be lower than that in fixed division. If print quality is
regarded as important, printing in fixed division is recommended.
The maximum number of activated dots in the initialisation status is
specified using the function switches.
64 through 256 dots can, however, are set using the command for
setting the number of dynamic division dots.