How Thermal Printers Work

In our daily life, we all come into contact with thermal paper. Unlike ordinary thermal paper, thermal paper produces marks by heating and does not require ink or ribbon for printing. So how is it done? This article will detail how thermal printers work and how to achieve inkless printing.

A thermal printer is a device that uses thermal paper or thermal labels to print. Its working principle is to use the characteristics of the thermal print head and thermal paper. By heating the thermal energy of the thermal print head product, a chemical reaction occurs at a specific position on the thermal paper to change the color of the paper, thereby achieving printing. Specifically, it consists of the following steps:

1. Signal input: Users input printing information through computers and other devices, which is transmitted to the thermal printer through data lines.
2. Thermal print head: The thermal print head is composed of many small resistors, each corresponding to a series of printed points. When the printer receives a signal, it generates a current. When the current passes through the resistor, the resistor heats up and is converted into heat energy.
3. Thermal paper: There is a layer of heat-sensitive coating on the surface of the thermal paper. After receiving heat energy, the coating will undergo a chemical reaction and change color at the relevant location.
4. Printing process: During printing, the control circuit applies current to the thermal print head according to the content to be printed, and the thermal print head heats the corresponding position.
5. Display: The pattern or text to be printed is displayed on the thermal paper, and printing is completed.

There are two common principles for realizing inkless printing technology:

1. Electrothermal chemical printing technology: Using electrochemical reactions to replace traditional ink and ribbon printing. Thermal paper usually contains two layers: one is the photosensitive layer, and the other is the protective layer. When current passes through the thermal print head in the printer, the thermal print head begins to heat. The thermochromic dye in the photosensitive layer of the thermal paper will be heated to its reaction temperature, a chemical reaction will occur, and the color will change to form a printed pattern or text.


2. Laser burning printing technology: Use laser beam to burn special photosensitive materials to form patterns and text. The photosensitive material is a special polymer film with a layer of ink primer on the material. The laser beam is focused on a specific position on the photosensitive material through the laser print head, and the laser energy is converted into heat energy, causing a burning reaction. The burning reaction causes the ink primer in local areas of the photosensitive material to change color, forming the desired pattern or text.

Thermal paper realizes ink-free printing through electric current heating and color change. Its working principle has more advantages than traditional ink printing and ribbon printing. Printing is convenient, fast, and does not require other consumables, greatly reducing printing costs.

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