Ricoh VT3500, Service Manual

Page: 173 / 330

For example, if all of one line data are black, the first and second outputs are
as follows:
[Previous Line’s Pixel is White]
A black datum is sent to the
corresponding thermal heating element
as the first output. The applied energy to
plot the pixel increases.
[Previous Line’s Pixel is Black]
A white datum is sent as the first output.
The applied energy to plot the pixel
decreases.
The line data sent to the thermal head drive PCB are stored in a line memory
(Memory 1). When the image data of the following scanning line are sent and
stored in the line memory, the previous line data move to another memory
(Memory 2). The line data and previous line data are compared, and the
pre-heat and/or cool data for each thermal heating element are serially sent
to the thermal head as the first output. The line data to plot the master are
picked out from the line memory (Memory 1) and are sent following the first
output.
The outputs are divided into four (DATA 1 to 4) in the image pixel data
decoder and are sent separately to the four blocks of the thermal head.
1153
~
2304
2305
~
3456
3457
~
4608
1
~
1152
CN705-16
R4608
72 55 54 37 36
19
18 2
1
R 1
Memory 1
Memory 2
Image
Data
Thermal Head Drive PCB
Thermal Head
1st Out put
2nd Out put
DATA 4
DATA 3
DATA 2
DATA 1
Block 4 Block 3 Block 2 Block 1
Previous Line
Plotting Line
1st Output
2nd Output
Main Scanning Direction
Black White
Image
Image
1 December 1993
2-137