When you go to a shopping mall to buy something you needed, the cashier will give you a ticket. Have you thought about how these ticket print out?
We usually refer to printing, is given by way of ink transferred to specific area of the paper, we want to give the text or graphics. Paper chemicals constitute any color of light absorption are not clear, so that when the light reflected from the surface of the paper into our eyes, we will see the white paper. The ink pigment or dye capable of some or all of the visible color of light absorption, so that when the ink is applied to the surface of the paper, on the surface of white paper put on color. We usually use inkjet printers or laser printers at home or office. The principle of the inkjet printer is ejecting fine droplets of ink onto the paper. The laser printer is trough electrostatic attraction method, the toner absorbed onto the photosensitive drum, and then transfer them to paper. However, shopping ticket printing is not carried out in such a way, it uses a special paper-thermal paper.
Compared with ordinary paper, thermal paper’s surface with a thin layer of multi-coating layer, which contains some special chemicals called leuco dye. Leuco dye itself is colorless, so bought a new thermal paper looks the same as regular white paper. However, once met the right condition, they will be a chemical reaction, new substances that absorb visible light, so we see color. At room temperature, the thermal paper looks as ordinary paper, once the temperature rises, the leuco dye and an acidic substance have been melted into liquid, can meet freely molecular reaction occurred immediately, so white paper show color soon. This is the reason for the name of thermal paper-only at high temperature to a certain extent it will make the paper color.
With thermal paper, we want to print out the text or graphics also need special printer, which is a thermal printer. Its internal structure is very simple, there is no cartridge, the main component is the drum and the print head. For small ticket printing thermal paper roll is usually made of a roll. When the roll of thermal paper in the printer, it will be transmitted in the forward drive roller, in contact with the print head. Surface of the printing head has many tiny semiconductor element, according to our text or graphics to be printed on a particular area of the paper is heated. At that moment thermal paper with the print head into contact, the temperature of the print head to produce an acidic substance such dyes and thermal paper together and melted into a liquid chemical reaction, so the surface of the paper appeared in the text or graphics. In the drum drive, a shopping small ticket was printed out.
Why customers choose thermal printers instead of laser or inkjet printers? Thermal printers with small volume, low cost, fast print, it’s more convenient for customers.
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