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Hi,
I am building my 3D DLP printer with an LCD screen. But I realized that the UV did not pass the screen ... making polymerization impossible.
I do not understand why the UV are stopped by the screen, do you have any ideas?
Information:
- I have 6x 405nm UV LEDs of 10W each : 60W in total.
- the screen has these characteristics:
Display size: 7 inches
Touch screen: does not support
Dimensions: 165 (W) × 100 (H) × 5 (D) mm
Observation area: 154.08 (H) × 85.92 (V)
Resolution: 1024 × 3 (rvb) × 600
Distance from Point: 0.05 (W) × 0.15 (H) mm
Viewing angle: L70 ° R70 ° U50 ° D60
Panel type: TFT
Display color: 262 K
Contrast: 500: 1
Brightness: 220cd / m2
Interface type: Digital
The number of connection: 50 pin digital (TTL) TCON
Backlight: LED
Applications: Mobile DVD, digital photo frame, automotive systems, multimedia applications and other audiovisual systems
I do not know if I'm in the right forum but I hope someone can help me.
Thank you
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The backlight should be removed
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Yes for the test I had already removed, but I found the solution thank you very much.
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Yes for the test I had already removed, but I found the solution thank you very much.
What was your solution?
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I bought another 8.9 "2K screen
"made for 3D DLP printers" according to the seller, but the resin still does not polymerize. I wonder if it's not the resin that would not work well. This is a sample that someone gave me but I do not know the characteristics of this resin. But in direct contact with UV led the resin works.
So I do not know where the problem is.
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On my printer I have the same problem after replacing the display instead of broken one. Replaced display is original (from printer seller) and the same as old broken. But now curing time became more then twice as much and still not enough for quality printing. I ask manufacturer about this. He told me about some darker polarized film on the top of the display. LCD display has 2 polarized films (top and buttom). Every such film in general LCD display absorbs more then 50% of UV 405nm. So the total absorbation is more then 75% of UV. If LCD has transflective mirror film on the buttom the total light transmission is lower. So, not every display is suitable for SLA. And 3D printer manufacturer can replace polarized film by another with higher UV transmittance
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yes, I also have a reflective film on the back. Do you know if we can replace this film or if we can buy a screen without this reflective film?
But I find it strange because some project on the internet works with a conventional screen, without modification. Like the printer from: https://www.youtube.com/watch?v=zdHR6w-UEnI or : https://www.youtube.com/watch?v=Mf8mAcwtlbU (both of them do several video on their 3D DLP printer and it both work.)
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Its transreflective film, not fully reflective. Its half transparent film. I want to try one of displays without this "mirror".
About UV transmittance. You wrote that total power is 60W. For 8.9" Display it seems to be very low power. If you drop some resin on the display it will be hardened?
Last edited by VikluhaVaklay (2019-07-24 09:49:32)
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For the power of the LEDs I compared with a whanao printer that has a UV LED of 30W, so I thought that 60 will be largely enough ..
And the resin hardened in a few seconds in direct contact with the UV but not on the screen.
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LEDs may be very different. If resin doesn't hardened on the display that means UV spectre needed for this resin is fully absorbed by the display. Did you unmount additional protective films and glasses? Some such glasses and films may cut UV at all. Did you try to use another kind of resin?
Last edited by VikluhaVaklay (2019-07-24 10:07:27)
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No, on the screen I simply removed the backlight, is it possible to remove the reflective part without making the screen unusable?
I only have a sample of resin that is quite old, but kept in a glass bottle in the shelter of the light.
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Resin may be suitable not for 405 nm UV spectre, and this "spectre noise lower 405nm" is mostly absorbed by the display. I advice you to try another resin suitable for 405nm UV. You could buy Anycubic resin, they declared compatibility with 405nm LED
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I'll see who gave me this resin this Thursday, so I'll have confirmation of the type of resin it is.
I spotted this resin cheap but effective and made for UV 405nm: https://www.atome3d.com/collections/fun … l?ls=fr-FR
Last edited by Pixel3D (2019-07-24 10:28:25)
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It may be obvious question but while testing you open shutter LCD fully without color filter?
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when I test the screen I display a totally white image
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You have to take all the films off the back of the LCD, not just the backlight. After the backlight, there are multiple reflective and refractive films that help distribute the light from the backlight across the screen. With no backlight, there is no more need of this films.
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