A weird and quirky idea - CRT shaped glass/acrylic slab for LCD screens.

[Maximus]

This has been running around my head for a little while now and I don't even know if the physics of the idea would even work, like I said in the title it's a bit of a weird idea but...

I'm thinking of a cast piece of uhmmmmm 'clear something' that's flat on the back and has the contour of a typical CRT screen on the front. Designed to sit flat against the surface of an LCD screen and give the curvature of a CRT, I'm wondering what effect the clear cast would have on the optics, whether you'd get any nice blooming etc.

  just one of the things that popped into my head one day 

[charlieram]

That could be quite interesting, especially if one side had something like a fresnel lens to give the impression of scan lines.

[CoryBee]

This has been running around my head for a little while now and I don't even know if the physics of the idea would even work, like I said in the title it's a bit of a weird idea but...

I'm thinking of a cast piece of uhmmmmm 'clear something' that's flat on the back and has the contour of a typical CRT screen on the front. Designed to sit flat against the surface of an LCD screen and give the curvature of a CRT, I'm wondering what effect the clear cast would have on the optics, whether you'd get any nice blooming etc.

  just one of the things that popped into my head one day 

I had knocked that idea around my head several times and getting a glass maker to do something like that would cost a bunch more than getting an actual CRT screen in there.

[jdbailey1206]

Yeah.  Glass is damned expensive.  You would almost need a Monitor Magnifier matched with a plano convex piece of glass.  CRT's just seem to be the way to go.

I would talk to Sjaak.  In his version of Fix It Felix he made it seem as though the screen is curved.  I'm sure that someone can create a program to give this illusion.

[Maximus]

Yeah there are filters that do a nice job of that. This was more of an experiment in physical approaches. Perhaps clear cast acrylic? I bout it would need to be more than about 3/4" thick

[BadMouth]

I'd think you'd need something with optical fiber properties, otherwise it would just look like an LCD at the bottom of a glass dome.

I remember having a rock like that once.  Not sure what it was made out of. 

[jdbailey1206]

This thread seems to show you how to achieve it with the software end.  I'm just at a loss on how one would accomplish this with an lcd monitor.  Physically I mean.

[BadMouth]

You could heat something like this over a CRT until it took the shape of the CRT glass.
http://www.ebay.com/itm/Full-Page-Magnifying-Sheet-Fresnel-Lens-3XMagnification-/250837545942?pt=LH_DefaultDomain_0&hash=item3a671533d6

If it's right up against the LCD, I guess there's a chance it wouldn't look horribly distorted.

[jdbailey1206]

Just wonder if that would work BadMouth if you shot the resolution on your monitor up.

[Maximus]

That's why I'm thinking it has to be cast, you need that solid piece to have the transmission quality that you are looking for, you can't have any gap between the surface of the LCD and the 'DOME'

[jdbailey1206]

Let me ask this.  What goal are you trying to reach by doing this?  Is it for the sake of doing it or are you just sick of finding CRT monitors since they are becoming so rare?

[EightBySix]

What about starting with a thick slab and shaping it? It could be machined/cnc cut and then polished

[Maximus]

Let me ask this.  What goal are you trying to reach by doing this?  Is it for the sake of doing it or are you just sick of finding CRT monitors since they are becoming so rare?

The reason I do everything 'I wonder if this will work' 

I just like the idea that there may be a possible new option out there for builders to try and recreate that CRT feel when one isn't available or practical for their project. Imagine being able to build a 25" 'CeeAreTee' (Copyright my brain) screen into an ultra slim full sized cab - all the advantages without the footprint.

[jdbailey1206]

The reason I do everything 'I wonder if this will work' 

I tried the 'I wonder if this will work' method once and got slapped.   

I got it!  We are working backwords!  Just bend the LCD!  Now that is a brain patent. 

Too late.

[Maximus]

You could heat something like this over a CRT until it took the shape of the CRT glass.
http://www.ebay.com/itm/Full-Page-Magnifying-Sheet-Fresnel-Lens-3XMagnification-/250837545942?pt=LH_DefaultDomain_0&hash=item3a671533d6

If it's right up against the LCD, I guess there's a chance it wouldn't look horribly distorted.

For that price it would be worth an experiment just for fun, although you'd need something a bit bigger to experiment with a common size 4:3 LCD like a 17" or 19". Hell I have a 23.1" 4:3 Planar sitting in my garage, it would be fun to see if I could get that to look all CeeAreTee Copyright JGD Brain Labs Inc. LLC .Org

[PL1]

Did a few experiments to see what would happen.

Fresnel lens placed on surface of LCD yields no magnification.

Add a layer of 1/4" plexi yields slight magnification.
(Directions recommend holding the lens 4" from the item you want to magnify)

The fresnel lens adds interference patterns, bending it makes them worse.

If you want to use casting acrylic, you might want to make a mold from the surface of a CRT -- not sure if it will work or if it will make the individual pixels stand out more.   


Scott

[Maximus]

Yep I don't think we want any magnification at all, and a Craftymech inline SLG would easily solve any scan line issues.

I like the idea of finding an existing piece of cast acrylic sheet maybe 1/2" or 3/4" thick and then possibly having it shaped and polished, although where???

[PL1]

Just spitballing here, but maybe something like this:

Start with a CRT -- preferrably a dead one.

Cut a piece of 1/4" acrylic slightly larger than the LCD.

Put the CRT face up in your powder coat oven with the acrylic on top.

Bake at 290(?) degrees until gravity bends the acrylic into a curve.

Allow it to cool.

Add side supports to the acrylic and use it as a mold.


Scott

[Maximus]

You can easily make a mold for a CRT with silicon, the hard part is casting clear acrylic that thick without any bubbles, also I am wondering how much it would cost for that much clear resin compared to the cost of buying a perfectly clear sheet and then milling it.

[Maximus]

To do a large monitor like the Planar 23.1" you'd need a 24" x24" sheet.

Some quick searches bring back these prices...

3/4" - $90 shipped - http://www.ebay.com/itm/Acrylic-Plexiglass-Plastic-Sheet-3-4-x-24-x-24-Clear-/141039391132
1/2" - $42+ shipping - http://freckleface.com/shopsite_sc/store/html/product75.html

But where/how would you get this shaped and polished.

[Maximus]

I used a calculator on the Smooth-on web site and it said that for a 1" thick 24x24" slab you would need 19lbs of product which seems like it would be crazy balls expensive so I don't think liquid casting would be a very viable option.

[ark_ader]

I would like to see a clear perspex cubed 4x LCD setup cab, so you can have four players in one game without bumping shoulders.

[paigeoliver]

I think the real longterm solution to getting the legacy CRT look in new displays will simply be a setting you can activate on the monitor.

An 8K resolution monitor should have more than enough resolution to do this, maybe even the 4K monitors could do it.

This is something that should be able to be programmed into the firmware of the monitor and will probably even eventually become necessary as the world is jammed packed with legacy video recordings that are too low quality to look right on a 1080p display much less a  7680 × 4320 Ultra-HD display.

[DGP]

What we need are smaller plasma sets without IR.

Although I would like to have one of those 4:3 Planar 23.1 LCD's. 

Jason

[UFO]

Just throwing it out there, but was reading with great interest about Mountain's Jukebox and his new method of vacuum bending etc...

Don't ask me any science questions - just do it.... somehow!

 

[Rick]

Just throwing it out there, but was reading with great interest about Mountain's Jukebox and his new method of vacuum bending etc... Don't ask me any science questions - just do it.... somehow!

Finally, someone posts something as crazy as my "bend it with your mind" idea. (Ok, so you're idea actually has merit. Damn.) Slick! Someone is thinking outside of the box!

[Maximus]

Slick! Someone is thinking outside of the box!

There is no spoon box

[Unstupid]

I think it would be easier to bend and lcd panel to the rounded dome shape...   

[SavannahLion]

I mentioned this elsewhere but I guess I wasn't elaborate enough.

Just spitballing here, but maybe something like this:

Start with a CRT -- preferrably a dead one.

Cut a piece of 1/4" acrylic slightly larger than the LCD.

Put the CRT face up in your powder coat oven with the acrylic on top.

Bake at 290(?) degrees until gravity bends the acrylic into a curve.

Allow it to cool.

Add side supports to the acrylic and use it as a mold.


Scott

This is the closest. I found a Mac forum (URL escapes me ATM) where old Apples are rebuilt with flat panels. To get the curved look, the dead CRT is removed and used for the Acrylic as either a "pull down" mold or in a vacuum mold.

Bubbling is often a problem but done correctly, you get a shaped piece of acrylic that fits the old shell exactly and gives a nice "pop" to the flat screen. The drawback of a "hollow" space between acrylic and monitor is obvious but unless you make an effort to look for it probably isn't that big of a deal. Overall, based on the build photos at the Apple forum, the results are very pleasing.

I thought of using a lens on a small flat before. Stole an interesting lens about 4" square from my brother in law. After teaching my five year old how to set random things on fire with it (all in the name of SCIENCE!!) I thought to show him what happens if I put the lens over his DSi screen. I was thinking of those old red digit calculators from yonkers ago.  The magnification was ridiculous and I think the line of focus is very narrowly defined for that kind of lens. I'm not an expert but given a monitor of X by Y you're almost guaranteed to find yourself grinding your own lens or find someone to do it for you. I honestly can see it happening but not cheaply or easily. Not as easily as the acrylic method.

[jimmer]

just wondering, when you've manufactured this lens and fixed it to your LCD panel, are you going to mount it all behind a flat sheet of plexi?

[jdbailey1206]

1" for thickness?  That seems to be a little over kill.  I put in .3 for a mold depth and got 1.96 Lbs.  Or .89 Kgs for those of us on the 'crazy' metric system.     That will get you 32 oz.  (1lb = 16 oz.)  I then found a website that offers a clear resin for $25.00 here.

I have not personally worked with resin. 
http://www.instructables.com/id/How-to-Polish-Resin/?ALLSTEPS]  Polishing Resin

Repairing Acrylic and Polycarbonate

And remember Edison once said that he figured out 1999 ways on how NOT to create a light bulb.  Hopefully you get this bird to fly.

[Maximus]

I think the important thing not to miss here is that whatever material you use it needs to be a solid block with one flat side that fits perfectly against the face of the LCD and the opposite side matches the contour of a CRT screen. Having an air gap in between will give a crappy effect.

[lilshawn]

what about heat forming the plexi over the tube as mentioned before...then trimming the plastic to the LCD size needed, sealing it to the LCD, and then filling the empty space with the liquid resin?

a similar technique is used in the old projection CRT TV's of the 80's and 90's. A lens was mounted to the front of the tube, then a liquid (coupling fluid) was inserted between the lens and the picture tube to "optically couple" them together.

[Maximus]

That sounds like it would work although what would you use to do that and have zero bubbles? Cool idea.

[lilshawn]

back in the day to force bubbles out of castings, they use to use a vacuum pump and vibration to pull out the air.

I would assume if you used a 2 part resin a guy would have to be super careful about introducing air into it as it was mixed. it would be hard, but doable.

what about something more of a liquid, like a ballistics gel. it' needn't be hard since it will be sealed away.

another alternative could be to seal the panel with silicone around the edge of the metal frame...apply the curved plastic to the front...seal it...and actually fill it with a liquid (mineral oil or silicon oil could work.)

Ive seen some pics of people who've built computers in mineral oil filled fishtanks... it shouldn't (in theory) eat the plastic on the LCD panel face. 

[NickG]

yes,yes.. cut the back from an old non-working crt, combine the methods used for making crt fishtanks and liquid lenses, you can seal the 'lens' instead of the lcd...maybe you even keep tint and front mask.

[RandyT]

Ok, I'll be the wet blanket.

I don't think anything one tries to do in this regard will give the effect desired.  CRT images are actually painted (with electrons) onto the phosphor, which is coating the interior surface of the tube  The only way to approximate something like this would be with an LCD projector, and a curved rear-projection screen, as this is essentially mimicking the way a CRT works.  One would, of course, need to apply any scanline treatments to the image through software.  Even after doing all of that, it still wouldn't be the same, as the pixels on a CRT are actually the light source, and they are sitting only about 1/4" under the face of the screen.

A large lens might get you part way there, but it will always look like a lens, with all of the off-axis aberrations, and cost more than a real CRT.  A domed piece of acrylic would just look like you put your LCD in an aquarium.

Wait for flexible OLED panels (or whatever tech replaces it) and then go nuts

[Maximus]

I was wondering about a small LED projector rear-projecting onto a light gray curved screen, using an SLG to generate the scanlines and then shifting the focus off just a tiny bit to soften the edges of the pixels, that would be an interesting effect.

[BadMouth]

I was wondering about a small LED projector rear-projecting onto a light gray curved screen, using an SLG to generate the scanlines and then shifting the focus off just a tiny bit to soften the edges of the pixels, that would be an interesting effect.

In using a projector you are taking up as much room as a CRT, so what is the benefit over using a CRT in the first place?

[Maximus]

Not necessarily you can bounce an image with a First Surface mirror although it will of course not be as space efficient as an LCD for sure.