LCD MSLA vs DLP Resin Printing

What is the difference between MSLA and DLP resin printers and which one should you get?

DLP printers like the Anycubic Photon Ultra or Mars 4 DLP are enhanced with actuated pixels that allow for a drastic increase in resolution. Even though the native resolution from the light source is low, the enhancement allows for theoretical XY resolutions of 0.04 mm, putting the Photon Ultra in-between monochrome screen printers like the Photon Mono and the Phrozen Mini 4K.

While the XY resolution is good, DLP printers are limited in size; this will be the biggest constraint for most consumers. However, if you are doing small commercial items such as jewelry or custom bullion then you will be able to take advantage of the reduced energy consumption and longer component lifespan compared to MSLA printers.

Resolution and Quality

To start, lets ask what is the resolution in terms of 3D printing? Commonly, you will see sizes of 35 µm to 50 µm for the newer monochrome resin printers, and we will convert this from micrometer to millimeter for simplicity's sake; these become 0.035 mm and 0.05 mm. This XY resolution is also known as the dot pitch, which is simply the distance between the center of two pixels. Another way of talking about the resolution is in terms of pixels per inch (PPI). The PPI is inverse to the dot pitch, so a smaller dot pitch and larger PPI means better resolution.


For the first example printer, we will first look at the Anycubic Photon Mono which has a dot pitch of 0.051 mm. The monochrome screen used is 2560 by 1620 pixels. The screen length of 130.05 mm and width of 82.58 mm matches the print area. The PPI for this printer is 498.3.

Then we will look at a higher resolution printer such as the Phrozen Mini 4K. This printer has a dot pitch of 0.0352 mm, a PPI of 722.3, a monochrome screen of 3840 by 2160 pixels, and a screen length of 135.04 mm and width of 75.96 mm.

Finally, lets look at the Anycubic Photon Ultra, the DLP printer. The optical resolution of the light source is only 1280 by 720 pixels, but due to the actuated pixels from the Texas Instrument's chipset, the image displayed on the resin is actually 2560 by 1440 pixels. The native resolution of 1280 by 720 pixels provides the advertised dot pitch of 0.08 mm and a PPI of 317.5 for the print length of 102.4 mm and width of 57.6 mm. The actuated pixels allow for the increased resolution of 2560 by 1440 pixels, thereby increasing the theoretical dot pitch to 0.04 mm and PPI to 635.
Texas Instruments confirms this on their TDS by stating "3.6 Megapixels, 2560 x 1440 pixels on the resin."

So what does this mean in terms of print accuracy and quality compared to the LCD printers? A printer like the Photon Ultra will fall in-between the Photon Mono and Mini 4K. If you are planning to make an upgrade in XY resolution from a Photon Mono, then you should consider both higher-resolution MSLA printers like the Mini 4K and DLP printers like the Photon Ultra.

Intended Line

Native

Actuated Pixels (Enhanced)

Components' Lifespan and Replacement Cost

Texas Instruments notes that projectors in their reliability labs were often able to last over 26,000 hours before any artifacts appear, but for budget-commercial projectors it is common to see manufacturers estimate a lifespan of only up to 20,000 hours. As for the cost, based on small projectors coming out of China, $100-200 is a good estimate for a replacement, and the final price will depend on how much profit the company wants.

Reduced Energy Consumption and Layer Times

The reduced energy consumption comes from two factors:

• The increased efficiency of UV light delivery to the resin
• Using LEDs with a lower total power consumption

The increased efficiency of UV light delivery is a result of removing the LCD screen as a barrier. Since the efficiency has increased, the LEDs can be toned down, and their power has to be reduced either way, due to the limitations of the TI chipset. However, there is a TI chipset that boasts the ability to handle increased power, and if we were to assume that the Photon Ultra carries the base chipset, then we can expect to see cure times below even 1.5 seconds in future models.

Sources

• 10.1016/j.bioactmat.2019.12.003
  
• https://superbacker.co/anycubic-photon-ultra/
  
• https://www.ti.com/lit/ml/sprpe98/sprpe98.pdf?ts=1630417210247
  
• https://www.ti.com/lit/ds/symlink/dlp300s.pdf?ts=1630244750796
  
• https://www.ti.com/lit/sl/dlpt019e/dlpt019e.pdf?ts=1630244329570
  
• https://www.ti.com/lit/an/dlpa078a/dlpa078a.pdf?ts=1630186939012
  
• https://www.ti.com/lit/an/dlpa008b/dlpa008b.pdf?ts=1630279247327
  
• https://www.ti.com/lit/an/dlpa052/dlpa052.pdf?ts=1630416489938
  

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