Epson Stylus COLOR 800 Service Manual page 57

‰Black head nozzle selector circuit
The printing data is input from the data input ports D0 to D15 of the IC2 E05B33CB gate array to the
gate array to be converted into serial data and output to the nozzle selector from the BBHDATA and
BHADATA ports. The data is then separated to 2 sides through the port BBHDATA and BHADATA
which are allocated with 2 lines of black nozzles; the lines #1, #3 and #2, #4 respectively. The smaller-
numbered nozzle on each line receives data faster. Data is transferred from IC2 gate array to Nozzle
selector IC IR 2C72C at 64 bit / 2.5 MHz synchronizing with the BHCLK (Clock signal) and BHLAT
(latch signal). On/Off status of each nozzle in the nozzle selector is determined based on the data
transferred.
‰Common driver circuit for the color head
The circuit structure for the color head is basically the same as for the black head. The common driver
IC18 HBD2813C produces trapezoidal waveforms by combining the 6 different signals CCHG, CND1,
CND2, CMD1, CMD2 and CKC output from the IC2 E05B33CB gate array. There are 7 particular
types of trapezoidal waveforms produced for normal dot mode, Micro dot mode and so on, and each
form varies depending on the width of the combined signals. The rising form is determined by the
CCHG and CKC regardless of the printing mode. The falling form is determined by the 2 different pairs
of signals; CND1 and CND2 in the normal dot mode, and CMD1 and CMD2 in micro dot mode. The
VH voltage adjusting value stored in the EEPROM, which is unique to each head is read into the gate
array, and then transferred in 8-bit serial data via SBDATA signal to be set in the common driver. With
this procedure, the internal resistance is determined and the driver waveform is adjusted as the result.
‰Color head nozzle selector circuit
The printing data is input from the data input port D0 to D15 of the IC2 E05B33CB gate array to the
gate array to be converted into serial data, and output to the nozzle selector from the YHDATA,
MHDATA, and CHDATA ports according to the color. The data is then allocated to the corresponding
nozzle lines, alternating 2 lines; from #1 to #2. Data is transferred from IC2 gate array to Nozzle
selector IC IR 2C72C at 64 bit / 2.5 MHz synchronizing with the BHCLK (Clock signal) and CHLAT
(latch signal). On/Off status of each nozzle in the nozzle selector is determined based on the data
transferred.
Rev. A
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Figure 2-19 Waveform Producing Process for Color Nozzles
Operating Principles
2-17