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The LCD resin printers I've looked at have pretty standard resolutions like for a smartphone and I understand they use the same technology. However, color LCD screens have three RGB sub-pixels for each color pixel. Check for example this magnified picture of an S-IPS LCD screen: enter image description here It seems like they could just omit the color filter and have three grayscale pixels for each color pixel.

3D printing just uses one color - UV. So why don't they have resolutions that are multiples of three of the usual resolutions?

All results about sub-pixels that I could find are about anti-aliasing, which is different (using the existing pixels better vs. having more pixels).

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    $\begingroup$ (As a reply on a now self deleted comment) I think that the OP is asking about LCD resin printers. $\endgroup$
    – Mick
    Jul 21, 2019 at 1:36
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    $\begingroup$ @Mick That is correct. $\endgroup$
    – Nobody
    Jul 22, 2019 at 9:23
  • $\begingroup$ Too speculative to be an answer: Probably because nobody has thought of doing this before. Or maybe people are doing it and we don't know about it? I can't think of any reason why it wouldn't work. As a side note, the resolution would only be tripled in one direction. $\endgroup$
    – Tom van der Zanden
    Jul 22, 2019 at 16:20
  • $\begingroup$ @TomvanderZanden I can hardly believe this, but if so, then I would be glad to triple the amount of pixels on mine. :D And yes, it's only tripled in one direction. And it also depends on the subpixel layout how the resolution would be increased exactly. $\endgroup$
    – Nobody
    Jul 22, 2019 at 16:32
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    $\begingroup$ I just realized it's possible they use smartphone panels including the color filters. Then the blue sub pixels would provide most of the light and the other sub pixels would be useless. $\endgroup$
    – Nobody
    Jul 22, 2019 at 21:37

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If what Thomas Sanladerer states is correct, the Mars 2 Pro (monochrome LCD, no color filter) has a layer time approximately 1/3 as long as the Mars/Pro printers (where color LCDs are used):

This would indicate that the light passing through the LCD, when the color filter is present, is 1/3. Put it in other words, only ONE subpixel is capable of transmitting UV light.

Consequently, using all of them would not improve resolution because the other subpixels are always opaque.

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It should be as simple as using a monochrome LCD. You don't actually want any color filters to interfere with the UV light.

Do we know that LCD printers are not using monochrome LCD panels? It always seemed so obvious that I assumed it was the practice. All you need are the front and back polarizer layer and the LCD itself to rotate the light.

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  • $\begingroup$ "Do we know that LCD printers are not using monochrome LCD panels?" That's the question. Resolution wise, they look like repurposed smartphone color panels (i.e. front and back polarizer layer and the lcd). $\endgroup$
    – Nobody
    Jul 22, 2019 at 18:23
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    $\begingroup$ The Wanhao Duplicator 7 apparently uses the LS055R1SX03 LCD which is an RGB LCD. These are obviously repurposed smartphone LCDs. There is very little demand for monochrome high-resolution LCDs so they would probably be prohibitively expensive (if available at all). $\endgroup$
    – Tom van der Zanden
    Jul 22, 2019 at 18:53
  • $\begingroup$ I agree that demand is low. Making anything in low volume is expensive unless you can piggy-back on the key tech. That said, some modifications are less costly than others. It is possible that a run of a few thousand panels could be done without the filter layer, or, perhaps more likely, with the filter layer but without colorants in the filter layer. The Alibaba site offers to ship the LS055R1SX03 LCD without a backlight specifically for resin 3D printers, but say nothing about the filter layer. It may be that all three colors are similarly transmissive of UV light. Only testing tells. $\endgroup$
    – cmm
    Jul 22, 2019 at 19:32
  • $\begingroup$ @TomvanderZanden That's the printer I own (well, plus version). :) Thanks, I will definitely try to make use of the subpixels then. I guess it's possible (even likely) that it would be sufficient to just use color .png instead of monochrome .png (i.e. the borders of white areas would appear in funny colors). That and a microscope to figure out the subpixel arrangement. Could probably use an existing slicer without modification by increasing the resolution there and then converting the output image files with a simple script. $\endgroup$
    – Nobody
    Jul 22, 2019 at 20:09
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    $\begingroup$ Different colors transmit UV differently. It may even be that only the blue color is transmissive and the other ones always opaque, even when theoretically ON. Using subpixels would require different exposure time and difficult or impossible calibration. $\endgroup$
    – FarO
    Dec 14, 2020 at 20:35

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