Before we delve into the differences between DLP and LCD, let's briefly understand what resin 3D printing is actually and how DLP and LCD work.

Resin 3D printing, also known as barrel polymerization, has three main flavors: SLA, DLP and LCD. This article will focus on DLP and LCD, but before trying to understand DLP and LCD, it is best to understand how SLA works.

All barrel polymerization technologies involve a photosensitive resin cured by a light source to produce a solid layer and ultimately the entire component. The resin is contained in a barrel or tank and cured on a construction platform that rises slowly from the tank as the part forms. The main difference between the three technologies discussed here is the light source.

The most famous and oldest of the three is stereolithography or SLA. It uses a laser guided by a galvanometer to cure the resin. The galvanometer can be considered as a mirror to guide the laser beam through the transparent tank bottom to a specific point on the construction platform.

Digital light processing (DLP) is not a laser, but uses a digital light projector to cure the resin. It flashes the image of the entire layer to the bottom of the bucket. Light is selectively guided using a digital micromirror device (DMD), a component composed of hundreds of thousands of micromirrors.

The layer generated by DLP printer consists of so-called voxels (equivalent to 3D of pixels). This is because the projector screen itself consists of pixels.

Compared with the other two technologies, LCD 3D printing is less common and almost the same as DLP. The LED will also flash through the LCD array, but not from the projector. The screen acts as a mask and displays only the pixels required by the current layer. Therefore, no special equipment is required to guide the light, just as in SLA and DLP.

Now that we have introduced the three main types of resin 3D printing, let's focus on the first two and determine the differences between them.

DLP projectors and LCD screens exist around us, in our schools, offices and homes. If you can imagine the difference between the two, you are already part of understanding the difference between DLP and LCD 3D printing.

Interrupter

The DLP projector creates an image of the layer by shining light through the lens onto the DMD, which must then direct the light to the bottom of the resin tank. Therefore, the light from the DLP projector must be extended from a small light source to cover a wide area. This essentially means that a wide model is more likely to have distorted pixels at its edges.

In addition, the number of pixels on the DLP projector is the same regardless of the print size. This means that smaller, narrower prints can have higher accuracy than wider prints done on the same DLP printer.

To visualize this effect, consider the photos you took on your smartphone. When you enlarge a photo, the sharpness decreases. This is what happens when you print large objects on a DLP printer - they are "shrunk".

In other words, it is important to remember that distortion can be corrected on more professional equipment with higher quality components. In addition, the "downsizing" problem does not necessarily mean that the DLP printer has poor print quality, but its resolution is more focused on smaller prints.

Liquid crystal display

The LCD 3D printer uses a series of UV LCDs as light sources. The light from the flat LCD panel shines directly on the construction area in a parallel manner. Since this light does not expand, pixel distortion is not a problem in LCD printing.

This means that the print quality of LCD printer depends on its LCD density. The more pixels it has, the better the print quality.

Compared with SLA, the benefit shared by DLP and LCD is the construction speed. Because there is a whole layer flashing at the same time, rather than a single point, these two technologies can usually produce parts faster.

DLP and LCD are used in dental, jewelry and engineering industries, to name just a few. Of course, a considerable number of amateurs use these two types of printers.

Throughout the market, the general trend is that DLP printers are more expensive and professional machines. LCD is a relatively new technology. So far, it mainly appears in desktop printers with reasonable prices.

As mentioned earlier, cheaper DLP printers sometimes suffer from slight voxel distortion. However, if more money is invested, this potential problem will become less problematic. This is because higher quality printers bring higher quality hardware designed to correct distortion.

In general, LCD 3D printers use cheaper components than DLP 3D printers, making them a cheaper resin 3D printing solution. This is a good thing because it extends the scope of resin 3D printing to a wider range of manufacturers.

Both DLP and LCD can achieve fast printing speed and excellent details, but with the increase of price, DLP 3D printer began to surpass LCD printer.

If you are a professional who needs high detail and fast printing speed, we suggest you consider using a professional DLP 3D printer. On the other hand, if you are a beginner of resin 3D printing, LCD will be a good choice.