Graphic Imagers : Wide Format Technology

The end products that you wish to manufacture will drive the equipment choice for the printer you purchase. Having said that, there are distinct advantages to understanding the pluses and minuses of each imaging technology and the end products it was designed to produce. Let's explore some of the common characteristics to better understand the variations inherent within these products.

In general terms, each piece of equipment used to output digitally imaged graphics could be classified into one of three format designations:

• Narrow format (less than 36" in width)

• Wide format (36" to 96")

• Grand format (greater than 96")

Speed

The print speed of any given device is dictated by its printing technology and the output resolution printed at. For inkjet printing systems, lowering a printer's output resolution will increase print speed. Increases in printing speed can also be achieved by using a printer that has multiple print heads for each ink color.

Resolution

Image resolution is the number of pixels displayed per unit of length in an image, usually measured in "pixels per inch" or "pixels per centimeter." Dots per inch, for example, typically refers to the number of dots printed along a linear inch or centimeter.

Number of Colors

The first color inkjet devices had four heads, one for each color: cyan, magenta, yellow and black, or CMYK. The limitations of this four head, four-color set appeared as banding in gradient fills and a somewhat compressed tonal scale. The next logical step was to introduce a light cyan (Lc) and a light magenta (Lm), with an additional head for each new color. While color choices range from four to twelve, six colors could be considered a realistic minimum for viewing close up POP display work. More colors expand the color gamut dramatically; while light or multi-density inks improve resolution, color vibrancy, blends and gradients.

Roll-to-Roll

Output Devices Roll-based digital output devices use a substrate delivered on a roll and printed after it is fed into the machine. Roll-based devices allow printing on flexible surfaces including paper, vinyl, fabrics and thin plastics, and on papers used in thermal image transfer processes such as dye sublimation.

Flatbed Inkjet Output Devices

Flatbed devices allow direct printing on rigid substrates, which can range from the common, such as poster board, foam board or rigid plastics; to the uncommon, including metal, glass, wood and other substrates. Printing directly on these rigid substrates may eliminate the mounting processes required of many images printed on roll-to-roll units.

Direct Photographic Imaging Exposure Technology

Direct photographic imaging consists of two primary technologies. The first uses three colored lasers (red, green and blue), controlled by sensors with an optical system. The exposure of the digitized images is made one line at a time, pixel by pixel, at the selected resolution of either 200 ppi or 400 ppi, on photosensitive roll materials. Another solution involves a solid state LED (light emitting diode) head that is coupled with an optical system providing resolutions of either 300 ppi or 425 ppi. Either system requires an RA4 photographic material processor for processing of the photographic media.

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