Printing Barcode

Barcode symbols can be produced on-site or off-site using a range of print technologies -- direct thermal, thermal transfer, dot matrix, ink jet, and laser -- each suited to different volumes and quality requirements.

Barcode symbols may be produced in a variety of ways: by direct marking, such as laser etching or ink jet printing, or, more commonly, by imaging or printing the barcode symbol onto a separate label. For our purposes, the terms "print" and "printer" refer to the production of a barcode whether the image is printed, etched, or imaged. The importance of precise barcode printing cannot be overstated; the success of the whole set of integrated technologies that comprise a barcode system depends on barcode print quality.

Barcode printing applications fall into two categories:

• ON-SITE, user-controlled printing
• OFF-SITE, label supplier-controlled printing

On-site printing generally takes place at or near the point of use. The data encoded is usually variable, entered by an operator via a keyboard or downloaded from the host computer. The most common barcode print technologies for on-site use are:

Direct Thermal: Heating elements in the printhead are selectively heated to form an image made of overlapping dots on a heat-sensitive substrate.

Thermal Transfer: Thermal transfer technology uses much the same type of printhead as direct thermal, except that an intervening ribbon coated with resin-based or wax-based ink is heated, transferring the image from the ribbon to the substrate.

Dot Matrix Impact: A moving printhead, with one or more vertical rows of hammers, produces images through multiple passes over a ribbon. These passes create rows of overlapping dots on the substrate to form an image. Serial dot matrix printers produce images character by character; high-volume dot matrix line printers print an entire line in one pass.

Ink Jet: This technology uses a fixed printhead with a number of tiny orifices that project tiny droplets of ink onto a substrate to form an image made of overlapping dots. Ink jet printers are used for in-line direct marking on products or containers.

Laser (Xerographic): The image is formed on an electrostatically charged, photo-conductive drum using a controlled laser beam. The charged areas attract toner particles, which are then transferred and fused onto the substrate.

On-site barcode printers come in a range of configurations as well as a wide variety of technologies. User choices include:

• Large, copy-machine-sized dot matrix line printers, in-line ink jet printers, or in-line thermal transfer print applicators for high-volume applications
• Desktop dot matrix, laser, direct thermal, and thermal transfer printers for variable-demand print jobs
• Wireless direct thermal or thermal transfer printers for portable and field applications

Clearly, with the staggering range of choices available, users need to carefully determine their application parameters before purchasing a barcode printer.

On-site printing most often involves purchasing label-design software in addition to printer hardware. Barcode printers come with their own proprietary programming languages that support all the standard symbologies, and are capable of printing simple static-data or serialized barcode labels on their own. However, labels requiring additional formatted text, graphics, or multiple fields will require a separate label-design software package. More than 100 such packages currently exist, designed for a wide range of platforms and offering an even wider range of features. Once the domain of programmers, label design can now be accomplished by non-programmers via easy-to-use WYSIWYG graphical interfaces.

Generally speaking, commercial label printers may use flexographic, letterpress, offset lithographic, rotogravure, photocomposition, hot stamping, laser etching, or digital processes to produce a consistently higher-grade label than those produced by on-site printers. If the content of the barcode symbol is known ahead of time, a commercial label supplier is generally the best choice. However, there are tradeoffs. Commercially supplied labels must be ordered, stocked, and kept in inventory. A business with frequent product line or label changes will need to weigh its options carefully.