Why can thermal paper print without ink or ribbon? This is because there is a thin coating on the surface of thermal paper, which contains some special chemicals called leuco dyes. Leuco dyes themselves are colorless, and at room temperature, thermal paper looks no different from ordinary paper.
Once the temperature rises, the leuco dyes and acidic substances melt into liquids one after another, and the molecules that can move freely react immediately when they meet, so the color quickly appears on the white paper. This is why thermal paper got its name – only when the temperature reaches a certain level will the paper change color.
In other words, when we print with thermal paper, the ink is not stored in the printer, but has been covered on the paper. With thermal paper, if you want to print text or graphics on its surface, you need a special printer to cooperate, which is a thermal printer.
If you have the opportunity to disassemble a thermal printer, you will find that its internal structure is very simple: there is no ink cartridge, and the main components are the roller and the print head.
The thermal paper used to print receipts is usually made into rolls. When a roll of thermal paper is put into the printer, it will be transported forward by the roller and contact the print head.
There are many tiny semiconductor components on the surface of the print head, which can heat specific areas of the paper according to the text or graphics we want to print.
At the moment when the thermal paper comes into contact with the print head, the high temperature generated by the print head causes the dye and acid on the surface of the thermal paper to melt into liquid and react chemically, so that text or graphics appear on the surface of the paper. Driven by the roller, a shopping receipt is printed.
Post time: Aug-05-2024