Thermal Receipt Printer

A thermal receipt printer (or direct thermal printer) produces a printed image by selectively heating coated thermo chromic paper (or thermal paper as it is commonly known) when the paper passes over the thermal print head. The coating turns black in the areas where it is heated, producing an image. Two-color direct thermal printers are capable of printing both black and an additional color (often red), by applying heat at two different temperatures.

Note: Thermal transfer printing is a related method that uses a heat-sensitive ribbon instead of heat-sensitive paper.

Essential Thermal Receipt Printer mechanisms

A thermal receipt printer comprises these key components:

• Thermal head — generates heat; prints on paper

• Platen — a rubber roller that feeds paper

• Spring — applies pressure to the thermal head, causing it to contact the thermo-sensitive paper

• Controller boards — for controlling the mechanism

In order to print, one inserts thermo-sensitive paper between the thermal head and the platen. The printer sends an electrical current to the heating register of the thermal head, which in turn generates heat in a prescribed pattern. The heat activates the thermo-sensitive coloring layer of the thermo-sensitive paper, which manifests a pattern of color change in response. Such a printing mechanism is known as a thermal system or direct system.

Controller boards are embedded with firmware to manage the thermal printer mechanisms. They can drive various sensors like paper low, paper out, door open, top of form etc., and they are available with the most commonly used interfaces (RS232, Parallel, USB, wireless). For POS application some boards can also control the cash drawer.

Dot Matrix Receipt Printer

Another type of popular receipt printer is the dot matrix receipt printer, which works like a typewriter by having its print head running back and forth on the page and prints by impact, striking and in-soaked cloth ribbon against the paper. Unlike a typewriter or, letters are drawn out of a dot matrix, and thus, varied fonts and arbitrary graphics can be produced.

Each dot is produced by a tiny metal rod, also called a "wire" or "pin". The moving portion of the printer is called the print head, and when running the printer as a generic text device generally prints one line of text at a time. Most dot matrix printers have a single vertical line of dot-making equipment on their print heads; others have a few interleaved rows in order to improve dot density.

Thermal VS. Dot Matrix

Thermal printers print faster and more quietly than dot matrix printer. They are also more economical since their only consumable is the paper itself. Even though the paper is more expensive, printers can be rapidly refilled, leading to almost zero downtime. Commercial applications of thermal printers include points of sale systems, filling station pumps, information kiosks, and voucher printers in slot machines.

Dot matrix printers, like any impact printer, can print on multi-part stationery or make carbon copies. Impact printers have one of the lowest printing costs per page. As the ink is running out, the printout gradually fades rather than suddenly stopping partway through a job. They are able to use continuous paper rather than requiring individual sheets, making them useful for data logging. They are good, reliable workhorses ideal for use in situations where printed content is more important than quality.

Dot matrix printers are usually noisier than thermal printers, to the extent that sound dampening enclosures are available for use in quiet environments. They can only print low resolution graphics, with limited color performance, limited quality and comparatively low speed.