4. How Card Printing Works

All Eltron plastic card printers feature the same basic printing operations - dye sublimation and/or thermal transfer printing. Both techniques involve a ribbon being heated as it passes under a thermal print head. The difference is that thermal transfer ribbons heat up and transfer ink onto the plastic card, and dye sublimation ribbons heat up and undergo a chemical change process that turns the ink into a gaseous state which then permeates the plastic card.

The ribbon used in color dye sublimation printing is divided into three separate color panels yellow, magenta, and cyan (see Figure 1). This configuration is referred to as YMC.

(Figure 1)
Yellow, magenta, and cyan are the primary colors used in printing
to produce all other colors including black.

The dye from the ribbon is applied to the plastic card via a multi-pass operation. This means the card will pass under the print head once for each of the three colored ribbon panels - the print head applies each color separately.

yellow	yellow & magenta	yellow, magenta & cyan

The term Dye Sublimation is also referred to as Dye Diffusion. When the Dye on the ribbon is heated by the print head it is transformed from a solid to a gas and diffused onto the plastic card (the card is specially coated to absorb the color dye). The hotter the elements in the print head, the more dye is converted to a gas and absorbed into the plastic card. At 300dpi the picture quality and continuous color tones produced by a dye sublimation printer outperform most laser or ink jet printers with higher resolutions.

The advantage of dye sublimation is the millions of colors that can be created. The colors result from a combination of the panels on the ribbon. By combining these colors and varying the intensity of the heat, providing various shades of each color, you are virtually unlimited in your color selection.

Thermal Transfer differs from Dye Sublimation in that Thermal Transfer uses Ink rather than Dye. Both Dye Sublimation and Thermal Ink (sometimes refered to as Resin) can be combined in one ribbon (see Figure 2). This ribbon is referred to as a YMCK Ribbon. The letter "K" is the designator for black in the printing industry.

(Figure 2)
Why do you need a separate black panel, when you can create
black by mixing the three basic YMC colors together?

When black is created by mixing the YMC colors together it creates what is referred to as "Composite Black." Composite Black typically looks muddy or has a grayish tint when compared to Thermal Transfer (TT or Resin) Black. Composite Black is not recommended for printing bar codes since combining the three colors together does not produce the sharp edge many scanners require. (This is invisible to the naked eye but can be observed under magnification). Composite Black is also invisible to IR scanners since there is no carbon in the dye. Since you may not know what type of scanner will be used, the rule is to always use TT (Resin) black to print bar codes.

All Eltron printers are capable of printing in monochrome using a single color ribbon. These ribbons are less expensive than full color multi-panel ribbons and can be either dye or ink (thermal transfer). The most commonly used monochrome ribbon is "Black" but there are several other colors available including red, green, blue, and yellow.

Dye Sublimation ribbons are preferred when you are printing pictures, since they can produce many shades of gray for a smoother look and a better picture quality. A resin black picture normally uses a dithered gray scale (gray made from a combination of pixels which limits the number of shades), producing a coarser, grainy look to the image.

Thermal Transfer (Resin) ribbons should be used to print text, bar codes or single color graphics such as simple logos. Black monochrome ribbons are represented by the letter "K" followed by a lower case "r or d", (Kr or Kd). The "r" designates a Thermal Transfer ribbon with resin ink. The "d" designates a dye sublimation ribbon.