Sony UP-890CE Service Manual page 49

INT-V A
a Synchronized
0 1 2 3 4 5 tts, 63 64 65
STB | | | | |
To us Te [Ts Ts LS ae Tes Tes
64CLK | |
——,
CLK | [ | |
5.3MHz '
4th stair
|
lst stair 2nd stair 3rd stair Sth stair 6th stair 64th stair
DATA 16 bara} fara] foaral foara) foata) _foatal [paral mal
|
64 bits transferred for one block ;
in all 16 blocks of data are sent in parallel
(64DATA X16=10240aTA)
OR
Fig.5-10. Stair Generation
5-6-3. Basic operation
All the signals are input to head from IC103. This section only explains the
operations for one block. (The operations for the other blocks are the same.)
(i) The 64 data items of screen printing are input to the shift register
synchronized with CLK.
(ii) When the STB pulse is input, the data input in (i) is moved from the shift
register section to the latch section.
(iii) When the DR pulse is input, the output stage transistors are switched ON/OFF
by the "H" and "L" latch section data. While the transistors are on, the
resistors heat up and thermosensitive paper changes color. The amount of heat
generated is controlled by varying the length of the DR pulses, so the color
darkness of the printing on thermosensitive paper can be varied.
* Note: The BEO terminal goes from "L" to "H" only when the power is turned on.
After that it stays "H".
5-6-4. 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 also possible to change the darkness
by changing the high and low data input to the latch section. This section explains
this method.
(i) The data recorded in video memory IC104 during print is input to gradation data
generation circuit IC103 by one print line using a picture variable power operation
circuit in IC103. The stair data generation circuit outputs the 6 bits of data
recorded in IC103 as one of 64 levels. If the 6-bit data is "3" , then DATA "H"
is sent to the head during the 1st, 2nd, and 3rd stairs of DATA 1 to 6 in Fig.5-
10, but from the 4th stairs and later, the DATA "L" is sent.
In this way, the screen is printed with the third stair, but from the fourth stair
and later is not printed.(See the explanation of the basic oerations in 5-6-3.)
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