Many of my friends refer to printers that use optical imaging as laser printers. In fact, this kind of design is not accurate because in optical imaging printers, in addition to laser printers that use lasers as imaging sources, LEDs that use LEDs as light sources are also available. printer. So, what are the differences in the working principle between LED printers and laser printers, and what are the advantages and disadvantages of LED printers?
Optical path principle of laser printers and LED printers
The imaging principle of the laser printer and the LED printer is basically the same, and the image latent image is formed by the light carrying the image signal on the photosensitive drum, and the image latent image is transferred to the printing paper and then fixed after the toner is absorbed. Finish the print job. The biggest difference is that the type of light source is different from the optical system.
The light source of the laser printer is a high-power laser diode. Under the control of the printing signal, the laser tube emits a laser beam according to the printing requirement. After the laser beam is focused by the focusing lens, it is projected onto a high-speed rotating polygon mirror, and the polygon mirror is not Stop rotating, changing the angle of the reflected laser beam at any time, thus forming a single-point beam with a change of position. After shaping and changing direction through the lens group, a reciprocating scanning axial laser is formed on the photosensitive drum to make the photosensitive The drum is exposed. After the single line is sensitized, the photosensitive drum rotates, and the laser beam continues to sensitize the next line, thereby completing the photosensitive process of the photosensitive drum.
The LED printer arranges thousands of tiny LED light-emitting diodes in a queue, placed in the axial direction of the photosensitive drum. Each physical resolution of the printer corresponds to one LED. Under the control of the printing signal, some LEDs need to be printed. The tubes are lit, and the light generated by them is directly projected on the surface of the photosensitive drum through the focusing head to expose the photosensitive drum. After the single-line photosensitive is completed, the photosensitive drum rotates, and the LED is again illuminated according to the printing requirement, so that the next line is photosensitive, thereby completing the photosensitive process.
Can I use an LED light source in a laser printer's optical path system or use a laser light source in an LED's optical path system? The answer is no, you should see that the laser printer's optical path system is long, the light has to be refracted and reflected many times, and the laser beam stays on the drum is very short. In this case, the ordinary light source will be Multiple times of refraction causes the light intensity to attenuate, and the light beam will diverge during the transmission process, resulting in insufficient light intensity to the surface of the photosensitive drum, and the beam diameter is large, so that the photosensitive drum cannot be normally exposed. Only laser beams with good transmission performance and concentrated power can meet the demand. The use of a laser tube for the optical path system of an LED printer is difficult to implement due to the complicated control circuit of the laser tube and high cost. The LED printer has a short optical path, and the light stays on the surface of the photosensitive drum for a long time, so that the ordinary light source can meet the requirements without using a laser.
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