The invention of Thermal Transfer printing

Jack Kilby, an electrical engineer, created the first semi-conductor based thermal printer in 1965 while working for Texas Instrument. He later received the nobel prize in 2000. The Silent 700, a computer terminal with a thermal printer, was released in the market in 1969. The Silent 700 was the first thermal print system that printed on thermal paper.

The process

One of the digital printing method, is Thermal Transfer. It works by melting a coated ribbon. The coating will stay glued to the material it is being printed on. The ribbon is coated with wax, wax-resin r resin and these are acting as ink when melted by the print head.The substrate to be printed on would typically be paper, synthetics, or textile materials. The print head, the ribbon and the substrate form a sandwich with the ribbon in the middle. It contrasts with direct thermal printing, where no ribbon is present in the process.

When higher durability of printed material is necessary is another reason to go with Thermal Transfer printing rather than Direct Thermal printing. Thermal transfer is used to print labels. It is the most used in the world to print high-quality barcodes. For added durability, the print can be laminated.

Inside the print heads are the electrical dots. Standard number of dots exist. There are 203 dpi, 300 dpi and 600 dpi. Each dot can be heated to a specific and adjustable temperature. The wax or resin-based ink on the ribbon film melts, and the pressure applied by the print-head transfers it onto the support material. When a dot is no longer heated and that part of the ribbon is not melting anymore, it is dry. As the substrate comes out of the printer, it is completely dry and can be used immediately.

Ribbons are on rolls and are fitted onto a spool holder inside the printer. The used ribbon is rewound by a take-up spindle, forming a roll of "used" ribbon. It is a "one-trip" ribbon because once used, the ribbon is thrown away. The main advantage of one-trip thermal transfer ribbons is the density of the image. Unlike dot-matrix impact printer ribbon that will fade over time, Thermal transfer printing is reliable.

Variants

Color thermal printers

Thermal printing technology can be used to produce color images as there are (Wax, Resin or a blend of the two) colored ribbons. When cooled, the ink is permanently adhered to the paper. This type of thermal printer uses a like-sized panel of ribbon for each page to be printed, regardless of the contents of the page. Monochrome printers have a unique panel for each page to be printed, while color printers have either three (CMY) or four (CMYK) colored panels for each page. Each color being printed separatey. The dot intensity these printers cannot vary on these printers, which means that images must be dithered. The quality does not compare with inkjet printers and color laser printers. Rarely used for full-page printing, it is now employed for industrial label printing due to its water-fastness and speed. These printers are trustworthy due to their small number of moving parts. Wax is sensitive to abrasion, as the wax ink can be scraped, brushed off, or smeared. However, wax-resin compounds and full resins can be used on materials such as polypropylene or polyester in order to increase permanence.

Usage of TT printers in industry includes:

Barcode labels and clothing labels (shirt size etc.).

Label with plastic, paper, and metal label materials.

Barcode printers are asking for sizes of 4, 6 or 8 inches (100, 150 or 200 mm) wide labels. They produce barcode labels for product and shipping identification.

Thermal Transfer printing