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Principle of dlplcd stereolithography 3D printing process

Nov 30,20

Principle of dlplcd stereolithography 3D printing process
At present, there are three mainstream single material photosensitive resin 3D printing technology: SLA, DLP, LCD. Today, let's learn about the other two (DLP / LCD) stereolithography 3D printing.
The most commonly used projectors in our daily life and office can be divided into two categories: DLP and LCD.
The working principle of DLP projection technology is: after the beam is decomposed into R, G and B primary colors through a high-speed rotating color wheel (color separation device, a prism), it projects DMD chip. DMD chip consists of many tiny lenses, each of which can rotate freely between + 10 ° and - 10 ° and is located by electromagnetic field. After the input signal is processed, it acts on the DMD chip to control the opening and deflection of the lens. After reflected by DMD lens, the incident light is projected and imaged by the projection lens (optical lens) and projected on the large screen.
The working principle of the three piece LCD projector is that the optical system forms R, G and B three beams of light through the beam splitter, which respectively transmits through the RGB three color liquid crystal board. The signal source is converted by ad, modulated and added to the liquid crystal board. By controlling the opening and closing of the liquid crystal unit, the on-off of the light path is controlled. Finally, the RGB light converges in the prism and is projected onto the screen by the projection lens to form a color image.
These two technologies have their own advantages and disadvantages. DLP projector produces a higher picture contrast, and the optical system is more compact, so it has advantages in volume and weight. Moreover, due to the reflective principle, DLP projector can achieve higher black-and-white contrast; LCD is a strong point in brightness uniformity, color and detail performance, but because LCD is converged into a pixel by three-color light, there will be some burr and shadow on the edge of pixel.
When these two kinds of projection technology are applied to stereolithography 3D printer, instead of single laser light source in SLA printer, it is a new PLD / LCD stereolithography equipment. The principle of these two new 3D printing and forming technologies is very simple. First, the model is sliced with slicing software, and the projector plays slides. Each layer of image generates photopolymerization reaction and solidifies in the thin area of resin layer to form a thin layer of parts. Then the molding table moves one layer, and the projector continues to play the next slide and continue to process the next layer, Through the end of printing, not only high precision molding, but also very fast printing speed.
What are the advantages and disadvantages of these two and similar molding methods?
In printing small parts, we have mentioned that DLP projection technology is based on reflective principle. Therefore, when displaying some thin lines and small font text, DLP projection is clearer than LCD projector. In this way, DLP printer is better than LCD in printing some small structure of model.
In terms of printing speed, the two printing principles are full face molding, so there is no obvious difference in printing speed.
In terms of equipment stability, these two kinds of UV curing molding technologies need to use high-power UV irradiation, and use a very small amount of UV light to cure. The LCD screen itself is afraid of ultraviolet radiation, and it will quickly aging after being irradiated. At the same time, the core component not only has to withstand the test of heat resistance and high temperature heat dissipation, but also has to withstand several hours of high-intensity baking of dozens of watt 405 LED lamp beads, so its service life is relatively short. If it is often used, its core component LCD screen will be damaged in a few months, so it is necessary to replace the LCD screen frequently. However, after a lot of innovation and optimization by some teams, the service life of LCD screen has been successfully increased to more than half a year.