User's Manual Part 1

3.3 CIRCUITRY
As shown in Figure 3-2, the printer has the following circuits:
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Print Head Circuitry
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Motor Control Circuitry
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Status Circuitry
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Host and Module Interconnect Ports
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Operator Panel Circuitry
If possible, spend some time with this figure. The intent is to offer another perspective to
descriptions given in other parts of the manual.
Printer Modules have three printed circuit boards—a Main CPU board, an Extension board, and
a second Processor board that controls Clear Material feeds. The figure depicts soldered-in
circuit blocks without shading. The lighter shading indicates socketed ICs. The darker shading
indicates external assemblies connected to the circuit boards by cabling.
The Microcontroller determines all operations through data and address busses and control
signals. Flash memory contains the associated micro-code. Note also that the Address bus
primarily serves transfers involving the Flash and DRAM chips. Most other data transfers occur
with a chip enable or other Microcontroller signal.
Two types of status are collected—sensor and parameter. Analog comparators receive inputs
from the LED-Photo transistor detectors. The D/A Converter allows the Microcontroller to
trigger an integration signal sent to the comparators placed on the Extension board.
Comparators operate using single-slope integration as a basis for checking sensor levels.
Single-slope integration times the interval between the start of a sawtooth wave and the point an
analog comparator switches state.
Motors exist in two types—dc, and stepper. The solenoid and all dc motors, including the one in
the Shear, receive 24-volt dc power. This same supply powers a dc-to-dc converter that delivers
5-volt power to the remaining circuitry.
Print data, still in compressed bit-map form, enters the RAM. After reception, the Microcontroller
sends the data to the Print Head Drive circuitry. Decompression occurs after the Microcontroller
retrieves data and before its delivery to the Print Head Drive circuitry.
Word-by-word, the data shifts into the 672 print head registers that feed the elements of the print
head. Print Head registers receive the data in two serial streams from the Print Head Drive
circuitry. For Clear Card color printing, the Microcontroller loads the 672 registers five times,
each time followed by a different pulse width that enables delivery of data to the Print Head
elements. Each pulse width produces a different heat for those elements that have received an
active data bit. Each element can, therefore, deposit up to 32 different dye densities on a card for
each of the ribbon panel colors. When expanded to include all ribbon panels, 32K possibilities
exist. This process continues for each line of imaging and through all panels of the installed color
ribbon. In contrast, monochrome imaging only employs one pulse width per line of imaging.
3-8
980286-001 Rev. A
CHAPTER 3
THEORY OF OPERATION