Printers can be divided into serial printers and parallel printers according to the data transmission mode.
According to the working principle of the printer, the printer is divided into two categories: hit type and non-impact type.
String dot matrix character non-impact printers There are mainly two kinds of inkjet and thermal printers. (1) Inkjet printer. The most widely used printer. The basic principle is that the charged inkjet fog spot is deflected by the electrode and directly forms the desired glyph on the paper. The advantage is that the dots that make up characters and images are much smaller than dot matrix printers, so the resolution of character dots is high, and the printing quality is high and clear. Character size and font can be changed flexibly and easily. Ordinary paper is used for printing, and this typewriter can also be used to print directly on certain products. There is no mechanical wear and tear during the formation of characters and graphics, and the printing energy consumption is small. Print speed up to 500 characters/second. Charge-controlled (high-pressure type) and random inkjet (negative pressure) inkjet technology are widely used, and dry inkjet printing technology has appeared. (2) Thermal printer.
The heat generated by the pulsed current flowing through the point resistance of the printing head is transferred to the thermal paper, causing it to be thermally discolored, thereby printing characters and images. The main features are no noise, light and small structure, and clear printing. The disadvantages are slow speed and poor handwriting preservation.
Line dot matrix character non-impact printers mainly include laser, electrostatic, magnetic and light-emitting diode printers. (1) Laser printer. The laser beam emitted by the laser source is modulated by the acousto-optic deflector controlled by the character dot matrix information, enters the optical system, and scans the rotating photoconductor drum laterally through a multi-sided prism, so that an electrostatic latent image of a character or image is formed on the photoguide film layer on the photoconductor drum, and then after development, transfer and fixing, the required character or image is obtained on paper. The main advantage is the high printing speed, which can reach more than 20,000 lines per minute. The quality of printing is high, the noise is small, ordinary paper can be used, and characters, graphics and images can be printed. Because of the high printing speed, macroscopically, it is like printing one page at a time, so it is also called a page printer. (2) Electrostatic printer. The pulse voltage is applied directly to a special paper with a layer of dielectric material in order to obtain an electrostatic latent image on the dielectric, which is developed and heated to form characters and images. It is characterized by high printing quality, no fading handwriting, long-term storage, low power consumption to generate latent images, no noise, simple and reliable. However, special paper is required and the cost is high. (3) Magnetic printer. It is the application and development of electronic copying technology. The use of magnetically sensitive media to form character latent images does not require a high-power laser source, and its advantage is that it is insensitive to humidity and temperature changes. The printing speed can reach 8000 lines/min. Simple structure and low cost. (4) Light-emitting diode printer. In addition to using light-emitting diodes as light sources, its working principle is similar to that of laser printers. Due to the use of light-emitting diodes, the cost is reduced and the power consumption is reduced.
