Retina iPad Display

[philipesantiago]

Hi there,

This is my first post, I just dropped by researching for sla 3d printing. Reading several threads here and learning a lot btw, this one got my eyes on.
Even though this is about ipad retina display, some ide as about general TF panels could be applied certainly.

- removing the color filter

There is a possible way of getting rid of color filter in to panels. The color filter is a photocured colored resin applied on to glass. It's done by photo lithography using high light transmission polymers. On top of it, the front polarizer sheet is glued. If the polarizer could be removed and the color filter be "printed" on the TF glass outside, the color filter could be washed out from the TF glass using some kind of solvent (e.g. acetone, gasoline, querosene, or any specific one, etc). Otherwise, no chance.





Removing the color filter could increase the light transmission and even get a possible resolution increase in width once there are 3 subpixel transistors (r, g, b) for each pixel. But this last one needs some work to output "colored slices".

This has never been tested, so it should be done in any old display first.


- Replacing both polarizer sheets

Some displays are uv filtered through its polarizers, so replacing these for those uv permissive sheets could open new possibilities to use real UV LEDS like 365nm that are more suitable to most resins. I don't really know if ipad display's polarizer are uv filtered or if there is a uv coating over the glass that could be removed as the color filter mentioned above.


Visible light polarizer


Uv polarizers



- adding micro lenses sheet

Using some kind of micro lenses sheet could help getting light coming from the leds more uniform without diffusing rays to much. There are different types that could be tested mainly changing the structure ( Convex semitubes, convex honeycomb, convex circular). However adding this layer in between LEDs and TF glass reduce some ligth transmission. Other issue could be high Temps coming from LEDs since those lenticular sheets are usually made of thermoplastics.








- oil cooling LEDs

About liquid cooling, this could be an alternative to keep LEDs cool, 'cause there's a better heating transport over fluids compared with air . Water could damage electronic components, so mineral oil seems to be a better alternative. Passive Heat sinks could be attached to the enclosure or even an active external PC liquid cooling could be adapted if Temps are too high.





So, sorry if I wrote I lot of bulls**t, I have no expertise on 3d printing, I'm just a "wanna be" that wants to help. Lcd masking seems really promising, faster and larger high detail prints while more compact printers.

Thanks for your patience and good luck on projects,

See ya

[PacManFan]

Thanks for the expert advice. This is a lot of good information. portions of this had been stated before, but this was very concisely written.
-Steve

[AndersonTa]

Used a radiometer to see how much power is being lost thru the screen...ultimately A LOT is being lost. So started to see if I could remove anything else, the back of the LCD assembly has a reflective mylar backing. Figured removing that would help...sadly, it didn't.

It doesn't seem to have done any harm either though, I did also accidentally take out a small piece of the polarizer. Take a look.

https://www.dropbox.com/s/wf5y2rub1pq3i ... 9.jpg?dl=0

[zachnfine]

A thought on the need for a display controller -- rather than hooking the iPad screen to a displayport-adapter connected to a Mac or a PC with a display port card, maybe the iPad screen could just be controlled by an actual iPad. It'd need to be set to not lock or power down when plugged in, notifications off, and with its browser open and aimed at a web page to which one's computer pushes image after image to expose each layer.

This would require splitting open an iPad, removing the screen, connecting the screen via some sort of LVDS extension cable (if that is possible), coding up a web page that displays images pushed from elsewhere, and altering existing SLA image display software to push images to a server rather than just display them in a window. There's also software like "Air Display" available, which allows an iPad screen to function as an additional display attached to a computer via network. Such an approach could be fun with an iPad mini retina resolution-wise, as that's a 7.9" 326ppi screen, and could also work with Android devices, some of which have high-ppi screens.

Just thinking out loud. I've seen used retina iPads as low as $189 on Cowboom. That's more spendy than the screens alone, but add in the displayport adapter and then a display port card for computer and it gets a little closer price-wise and might reduce the complexity (or increase it, I dunno).

[AndersonTa]

Well, made some bad assumptions about the layer heights I've been using. I thought I was <50 microns but in reality I was closer to 170 microns! So 8 seconds at 170 micron layers is not bad at all, exposure time should go down w/ smaller layer heights.

Also having removed that layer of mylar on the back of the screen (I'm also assuming it is mylar based on others discussion of it), it has little difference, so it would be best not to remove it in the future.

Here is a short vid of exposed base of the Vornoi Bunny by Virtox. Good test for controlled curing and intricate features, voids stay open and no signs of webbing.

https://www.dropbox.com/s/g4vbo83w7wrii ... 1.mov?dl=0

[g4uts]

I have built a dlp printer, with usable Resin i sourced from mainland china. I am so inspired by you guys and tried to make new one with retina lcd screen. However, I failed on retina display on every attempts.

Here are the attempts:
1 Bridgelux 210w led, can cure resin instantly, but can't cure through the lcd.
2 my dlp projector, can't cure through LCD screen.
3 3w led , 400-410nm, 410-420nm, 420-430nm failed through lcd Screen.

I have no idea, what may go wrong, I've taken retina screen apart as you guys did, front is black color and back is shining silver. It didn't let much light through though.

[zachnfine]

[Phife]

[zachnfine]

[Phife]

Removing the polarizers is not too diffucult, replacement can be done, but the non-uv blocking polarizers are expensive and then there's the potential damage to the liquid crystals when exposed to UV.

I think eventually it will be the way to go, perhaps a custom LCD can be made for our purpose one day but for now this is where we are at.