Ink Jet Printer

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    HIGH-LEVEL VIEW OF PLOTTING PROCESS

    HP-GL/2

    HP Graphics Language. Postscript Page Description Language.

    Page script is interpreted and then converted into raster

    format.

    Raster Format

    Picture in two dimensional array of dots. Quadruplet of intensities Red, Green, Blue, Black.

    Plotter Controller Reads rasterized image and sends

    command to plotter carriage to put ink on paper.

    Print engine

    Plotter carriage and other units.

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    HIGH-LEVEL VIEW OF PLOTTING PROCESS

    HP-GL/2 PostScript

    Rasterizer

    Raster memory

    Plotter controller

    PLOTTERCARRIAGE

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    DESIGN CONSIDERATIONS

    Memory space is important

    36 inch plot at 300 dpi.

    Reduce the amount of raster memory.

    Real time control is required

    Very high speed control to transfer ink to paper.

    Intensity must be controlled.

    Head is scanned across page and paper moved with servo

    Multiple events are happening at once

    Events are ink jets, Head, Paper, Carriage.

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    ARCHITECTURAL DIFFICULTIES

    Specialized graphics processors too slow

    General purpose processor

    for parsing

    Graphics chip raster conversion.

    DESIGN COMPONENTS

    Single RISC microprocessor

    Intel 80960 KA

    Modular I/O port

    RS 232/422 and parallel interfaces

    Single inline Memory Modules(SIMM)

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    HARDWARE DESIGN

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    CONT...

    RISC microprocessor

    Two microcontrollers

    Three Application specific IC

    Pen interface ASIC

    Processor support ASIC

    Carriage ASIC

    Servo processor controls servo motor on print carriage,

    front panel display, scans keyboard and runs service

    station

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    PARSING & RASTERIZATION

    Page description comes through I/O port to mainprocessor and memory

    Page description is parsed and pixels are generated.

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    SWATH GENERATION

    Generated pixels are stored in swath section of rasterized plot.

    Swath memory is kept separated from main processor memory

    Pixels from main processor are in row order which must be fed incolumn

    Swath memory is used by pen interface ASIC.

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    DRAWING

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    PROCESSOR SUPPORT ASIC

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    CONT...

    It connects 960 and servo processor

    Main processor allows it to talk to 960 and generateinterrupts.

    Servo processor interface talks to 8052

    Intercommunication block communication between two

    processors. Motion controller decodes position of print carriage and

    paper axes.

    Fire pulse controller synchronizing output for each

    column of pen data DRAM controller refresh signals

    Serial I/O interface basic RS-232/422 interface.

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    PEN INTERFACE ASIC

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    CONT...

    Key component of shuffler subsystem

    Pixel address generator SRAM array for programmable

    sequencer, column counter, adder.

    Pixel counter

    counts number of pixels to be printed

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    CARRIAGE ASIC

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    CONT..

    Delayed pipeline registers are programmed with delay

    values in order to control pen alignment.

    Shuffling algorithm in pen interface and carriage ASIC

    Algorithm were developed using Behavioural model in C

    Graphical stubs for both input and output are used to

    visualize the result

    Processor-support and pen-notify ASIC were build with

    combination of fast high speed PLD, standard parts, UART

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    SOFTWARE DESIGN

    Three challenges faced by designers

    Hardware platform not available for several months

    Unfamiliar with 960

    Team was small

    Software development environment run on Unix

    workstation

    Main processor was developed around Real Time

    Operating System(RTOS)

    HP-GL/2 language subsystem was used on printers.

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    THANK YOU