Top Thermal Receipt Printers
A thermal printer is a printer that uses heat and heat sensitive thermal paper to create a printout of text or graphics.
Thermal print heads consist of a series of heat points that are lined up and turned on and off as the paper or label passes under the printhead. In order to make a horizontal line across the paper, all of the heat points would need to be activated at the same time. To make a vertical line, a single heat point will be turned on and kept on as the paper gets pushed out of the printer. Any kind of diagonal line or shape would be a combination of the two techniques.
Thermal printing has become very popular in the Point of Sale industry in regards to receipt printing and label printing because it is faster and quieter than a printer that uses bond paper, ribbon, and impact printing methods. A thermal printer's speed is measured in inches per second or ips, with a slow printer being in the 2 ips range and a fast printer being 8 ips.
The quality of a thermal printer is measured in dots per inch or dpi. The more dots that the printer can print in a square inch the more fine and detailed the graphics and text can be. It's like drawing a picture with a marker versus drawing with a pencil. Most printers are in the 203 dpi range which can print the majority of fonts and standard sized barcodes.
Thermal printers cannot do any kind of gray scale. All graphics with a thermal printer are all done with mono-chrome dithering, meaning, the thermal printer will use a series of dots, lines, or shapes to fill in an area. Having more dots used in an area results in a darker shade of gray, where less dots will be lighter. The printer then uses this gradient logic to create the graphics.
Receipt printers use a continous paper that automatically adjusts its length to the size of the receipt. These printers come with an auto-cutter, cutting the receipt off at the end of the print or they have a tear bar.
Label printers typically use dye cut labels that are placed on a translucent backing and fed through the printer using a light to find the gaps between the labels. These printers can either use direct thermal printing in which the label changes color with heat, or thermal transfer printing which uses the same process but has a ribbon that transfers onto a non-heat sensitive label.