Label Printer - Mechanisms

Mechanisms

Label printers use a wide range of label materials, including paper and synthetic polymer ("plastic") materials. Several types of print mechanisms are also used, including laser and impact, but thermal printer mechanisms are probably the most common. Two types of thermal printer are seen:

• Direct Thermal - Uses heat sensitive paper (similar to thermal fax paper). Direct thermal labels tend to fade over time (typically 6 to 12 months); if exposed to heat, direct sunlight or chemical vapors, the life is shortened. Therefore, direct thermal labels are primarily used for short duration applications, such as shipping labels.
• Thermal Transfer - Uses heat to transfer ink from ribbon onto the label for a permanent print. Some thermal transfer printers are also capable of direct thermal printing.

There are three grades of ribbon for use with a thermal transfer printers:

• Wax is the most popular with some smudge resistance, and is suitable for matte and semi-gloss paper labels.
• Wax / Resin is smudge resistant, suitable for semi-gloss paper and some synthetic labels.
• Resin is scratch and chemical resistant, suitable for coated synthetic labels.

When printing on continuous label stock, there is a tendency for the print location to shift slightly from label to label. To ensure registration of the print area with the target media, many label printers use a sensor that detects a gap, notch, line or perforation between labels. This allows the printer to adjust the intake of label stock so that the print aligns correctly with the media.