What Is a Thermal Printer?
A thermal printer is a contact-type printer that prints by thermal transfer by pressing a metal letterform onto a printer tape called foil tape.
Features of Thermal Printers
- No drying is required because foil tape is used instead of ink.
- Clear printing.
- No need to clean hands or machine.
- The print is pressed against the substrate, making it uneven and difficult to tamper with.
However, compared to non-contact inkjet printers, the following disadvantages exist:
- Running costs for printer tape, type, etc. are required.
- Takes time for heating or cooling at startup or after trouble stops.
- Printer tape roll-in may occur.
- Printing may not be stable due to wear of the type or variations in contact pressure.
Uses of Thermal Printers
Thermal printers are mainly used to print expiration dates, lot numbers, and factory-specific symbols on product packaging films.
In horizontal pillow packaging, in which products flowing on a conveyor belt are packaged, continuous thermal printers are used, in which the type portion rotates to print continuously.
On the other hand, for vertical pillow packaging, in which liquid or powder is dropped onto the conveyor belt, an intermittent thermal printer is used to print when the film is sealed or cut.
Since foil tape is used, the machine and hands are less likely to get dirty, making it suitable for printing on packaging for food and medical products.
Principle of Thermal Printers
Thermal printers use foil, not ink, for the printer tape. By pressing metal type heated to approximately 150°C against the object to be printed through the printer tape, the foil is peeled off from the printed area and transferred to the object to be printed.
The foil tape transferred by heat consists of a film, a release layer, a color layer, and an adhesive layer from the type side. Unlike ink, there is no need to allow drying time after heat transfer.
The disadvantage of using thermal printers is that it takes time to change the printer tape and to reach the transfer temperature. Therefore, since around 2000, thermal printers, which do not use type and allow non-contact thermal transfer, have been widely used.
Thermal printers are attractive in that they can print barcodes in addition to letters because they do not use type.