Sony UP-980 - 4-6-3. Stair Generation; 4-6-4. Temperature Compensation; 4-6-5. Line Number Correction

4-6-3. Stair Generation
As explained in the last section on basic operation, the darkness of the printing can be controlled with the DR pulses,
but it is possible to change the darkness by changing the “H” and “L” data input to the latch section.
The method is explained as follows.
(1) One line image data recorded in image memory IC602 and 603 is fetched to line memory inside of IC601 every print
operation one line (nINTV) by controlling IC601.
(2) Fetched data in line memory is inputted to the stair generation circuit inside of IC601. The stair data generation circuit
outputs fetched 8 bit data in line memory as | through 256 stair data. If 8 bit data is 128, } through 128 stair of data 1
through 16 outputs “H” against the head, 129 stair or more outputs the data “L”.
(3) Output data from data generation circuit to the head is transferred to the shift register section of the head with
synchronized CLK outputted from IC601.
(4) When [C601 inputs the “1” STB pulse to the head, the 1st stair data is transferred to the latch section and 2nd stair data
is inputted to the shift register section. At the same time, the DR pulse goes to “L” and the “H” data among the data
input as the first stair data switches on the corresponding output stage transistors, heating up the corresponding resistors.
The “L” data switches OFF the corresponding output stage transistors so those resistors do not heat up. This operation
is carried out 256 times. If “H” data is sent the 1 through 256 times, the resistors generate heat the entire time and the
printing is the blackest possible. If the “H” data is only high until the 1 through 128 times, the printing is an
intermediate stair. This is how intermediate stairs are generated by sending number of data corresponding 8 bit data
size to the head and generating heat in the resistors that many times.
(5) Thus, by controlling the time until the next data is transferred to the latch, the darkness of intermediate stairs can be
achieved simply. In other words, intermediate stair darkness can be controlled by changing the STB intervals, T1, T2,
T3, T4, TS, T6 — T256. In this unit, IC601 matches the intervals T] to T256 to the paper’s gamma characteristic. This
is called gamma characteristic control.
(6) If the DR pulse is also controlled as described in 4-6-2. Basic Operation, even fine stair can be expressed.
Note: The portion () is generated when the STB pulse T interval is shorter than the transmission time to shift
resistor.
Thus, this unit provides smooth expression of intermediate stairs by controlling the STB pulse T interval and the DR pulse.
4-6-4. Temperature Compensation
As explained in 4-6-3. Stair Generation, intermediate stair are expressed by controlling the STB pulse T interval and the
DR pulses, but since the energy required to make thermosensitive paper turn color varies with the room temperature and
with the heat generated by and built up in the printing head during continuous printing. In this unit, 1C505 measures the
temperature change of the head from the thermistor (CN202 pins 15 and 16) included in thermal head and converts head
temperature data of 8 bit. IC505 corrects density change against the temperature by reflecting gamma characteristic control
of
IC601.
[C601
performs
to
compensate
for
temperature
change
controls
the
STB
pulse
T
interval
and
the
DR
pulse,
just
as
is
done
for
stair
generation.
Specifically,
when
the
temperature
rises
it
reduces
the
STB
pulse
T
interval
and
the
DR
pulses, but when the temperature falls, it increases the STB pulse T interval and the DR pulses.
4-6-5. Line Number Correction
When all resistors of the head are switched ON or when some resistors of the head are switched ON, total currents through
the
head
are
different.
Therefore,
the
energy
applied
to
each
resistor
has
an
error.
If
printing
operation
is
performed
without this correction, as a result, there is a line on the print where numbers of ON resistor are rapidly changed. And this
unit has [C601 that includes correction circuit of this.
4-16 UP-980(UC)
UP-980CE(CE)