This has been a project I've had in mind since I saw the specs on the LG G3 phone. It would offer a HD resolution projector in a MUCH smaller size. However, this build does pose a few significant challenges I'll need some help with.
1) Isolating the LCD screen in this screen assembly is exceptionally difficult due to the use of industrial adhesive binding the glass, LCD, and digitizer together. Using a head gun to melt the glue is the most common approach to separating these parts. However, this will greatly shorten the life span of the LCD if not outright break it. However, if I can figure out exactly what type of glue was used, I might be able to find a compound or process that could remove it. Worst comes to worst, I'll have to carefully scrape the glue away. This I can probably figure out on my own, but any advice from anyone who has dealt with a similar situation would be really useful.
2) I'm not knowledgeable in the area of computer hardware. This screen obviously doesn't come with the same circuit board that a TV does, so one will have to be improvised. Ideally, I want this projector to project in as high a quality as possible and accept common video inputs. The screen itself has 1440 x 2560 pixels, so the image would have to be limited to whatever the source is, otherwise the projection would look very distorted. This is the thing I REALLY need help with, so any advice would be appreciated.
3) Because 5.5" x 3" is an odd size, finding the right Fresnel lenses might be difficult. I've done some research, but I haven't been able to find a lens with the right dimensions. If anyone knows a good place to look or a way around this problem, I'd be eternally grateful.
4) This is really just a personal preference, but I'd really like it to have an adjustable lens so I could modify the image when I bring it over someone else's house. Being that this would be a small build, it seems like it could be portable. Having the projection be adaptable would really help in that regard. However, that might be more trouble than it's worth.
Also, because of the small dimensions of the LED screen, I was curious if a light source that doesn't require a ballast could be used. I could save a lot of money if that was the case.
If this build is successful, I think the small size and quality would really make the DIY projector market seem much more attractive to the average consumer.
1) Isolating the LCD screen in this screen assembly is exceptionally difficult due to the use of industrial adhesive binding the glass, LCD, and digitizer together. Using a head gun to melt the glue is the most common approach to separating these parts. However, this will greatly shorten the life span of the LCD if not outright break it. However, if I can figure out exactly what type of glue was used, I might be able to find a compound or process that could remove it. Worst comes to worst, I'll have to carefully scrape the glue away. This I can probably figure out on my own, but any advice from anyone who has dealt with a similar situation would be really useful.
2) I'm not knowledgeable in the area of computer hardware. This screen obviously doesn't come with the same circuit board that a TV does, so one will have to be improvised. Ideally, I want this projector to project in as high a quality as possible and accept common video inputs. The screen itself has 1440 x 2560 pixels, so the image would have to be limited to whatever the source is, otherwise the projection would look very distorted. This is the thing I REALLY need help with, so any advice would be appreciated.
3) Because 5.5" x 3" is an odd size, finding the right Fresnel lenses might be difficult. I've done some research, but I haven't been able to find a lens with the right dimensions. If anyone knows a good place to look or a way around this problem, I'd be eternally grateful.
4) This is really just a personal preference, but I'd really like it to have an adjustable lens so I could modify the image when I bring it over someone else's house. Being that this would be a small build, it seems like it could be portable. Having the projection be adaptable would really help in that regard. However, that might be more trouble than it's worth.
Also, because of the small dimensions of the LED screen, I was curious if a light source that doesn't require a ballast could be used. I could save a lot of money if that was the case.
If this build is successful, I think the small size and quality would really make the DIY projector market seem much more attractive to the average consumer.
Awesome project you set your mind on and this crossed my mind a few times after I got a G3 off ebay for dirt cheap that can't make calls or have it's memory extended with an SD card.
1)Why isolate the IPS screen from the digitizer and Gorilla glass at all? I don't see the digitizer and Gorilla glass having a major impact on the transparency or clarity of the image. Just use a bluetooth mouse and pair it with the G3 (plenty of tutorials and videos on how to do this) and voila you have a mouse to move around which gives you full functionality as the digitizer does.
2)Again why do you want to completely isolate the screen from the phone. It's much much easier to just use the onboard memory or an sd card to put movies on and supports subtitles as well. sure you can probably get someone to design a controller for the screen and have all of those inputs you want, but the price would just be unreal.
3)Depends where you're based and you can find plenty from China, but I live in the UK and there's lots of small lenses on ebay here
4)If by an adjustable lens you mean a zoom lens, forget about it now. even with such a small size screen it would still be very very hard designing a decent quality zoom lens and not to mention you'd have to sell your house to pay for it.
In theory yes, practice NO. Why? Because any other light sources other than metal halide, xenon or mercury lamps, all of which require ballasts, are WAY to dim and spread out their lumens over a very large surface area.
You definitely don't want to use those "high power" leds off ebay as they are very dim in comparison to a MH light and have a very large emitting area which would give you a TERRIBLE focus across the screen, especially in the corners.
There are small and insanely bright leds like the Phlatlight range from Luminus or Cree, but Luminus are the most bright and compact ones. Never tried one of these myself but I still doubt you would get a decent screen brightness out of them.
I hope I didn't burst your bubble and you stick with this as this would be an awesome build
good luck
1)Why isolate the IPS screen from the digitizer and Gorilla glass at all? I don't see the digitizer and Gorilla glass having a major impact on the transparency or clarity of the image. Just use a bluetooth mouse and pair it with the G3 (plenty of tutorials and videos on how to do this) and voila you have a mouse to move around which gives you full functionality as the digitizer does.
2)Again why do you want to completely isolate the screen from the phone. It's much much easier to just use the onboard memory or an sd card to put movies on and supports subtitles as well. sure you can probably get someone to design a controller for the screen and have all of those inputs you want, but the price would just be unreal.
3)Depends where you're based and you can find plenty from China, but I live in the UK and there's lots of small lenses on ebay here
4)If by an adjustable lens you mean a zoom lens, forget about it now. even with such a small size screen it would still be very very hard designing a decent quality zoom lens and not to mention you'd have to sell your house to pay for it.
In theory yes, practice NO. Why? Because any other light sources other than metal halide, xenon or mercury lamps, all of which require ballasts, are WAY to dim and spread out their lumens over a very large surface area.
You definitely don't want to use those "high power" leds off ebay as they are very dim in comparison to a MH light and have a very large emitting area which would give you a TERRIBLE focus across the screen, especially in the corners.
There are small and insanely bright leds like the Phlatlight range from Luminus or Cree, but Luminus are the most bright and compact ones. Never tried one of these myself but I still doubt you would get a decent screen brightness out of them.
I hope I didn't burst your bubble and you stick with this as this would be an awesome build
good luck
Thanks for the awesome feedback. I was not aware that the digitizer was not in the way of the projection, I had assumed it would need to be removed to project through the LCD. I also assumed that the glass would distort the projection. Since neither of these are the case, this build should be a lot easier.
I wasn't planning on using this just for movies. I was going to use it as a projection screen for my desktop, where game emulators and videos could be played from easily. Because of that, translating the input of the phone to at least my desktop would be a must. Being that I'm not very well versed in computer hardware, that seemed like the most daunting task...and as you said, probably the most expensive. I will be rooming with some computer engineers and software engineers this year though, so we might be able to work something out since we'll all be using it if we can get it to work.
I tried finding the lenses I needed on google, but couldn't find the exact measurement...probably because I was using the English system. I'll look again with the metric system...that only just occurred to me and now I feel stupid.
If you happened to find a lens which exactly met my specifications, I'd appreciate a link in case I'm still unable to find just what I need.
Those LEDs you mentioned sounded interesting...but by the time I got enough of them close enough together to produce the needed brightness, it would probably end up more expensive than a ballast and a strong lightsource. I'll probably just go the traditional route with this one.
I had wondered why none of the diy projectors had a zoom lens, now I know. It would have been pretty cool to have, but I guess I'll have to figure out a good common range which will work in both my dorm and the average dorm.
You've been tremendously helpful. If I happen to get this build working I'll post the specs, build instructions, and any files needed to make the board work.
One of my previous projectors had a 5.6" 720p LCD and I used a 120mm collector fresnel and a 180mm field fresnel and 180mm Kodak projection lens.
This gave me an 80" image from around 2.8 meters from the screen which I found was the ideal ratio for me.
I attached an awesome calculator app that lets you play around with those distances and also gives you distances from LCD - lens, lens - fresnel, etc. This small app was created by Dazzla on the Lumenlab forums which shut down a while ago, but the thing is I couldn't get it to work on any OS higher than XP but if you can get XP this app will definitely help you.
You can also try this ALLINBOX from the awesome allinbox.com website which is in French but has loads of useful info.
I looked around for small fresnel lenses and couldn't find much. I managed to find the exact same ones I used in my old projector though.
Rigid Fresnel Lens Sheet Magnifier Magnifying Glass 163mm x 107mm (6.5" x 4") | eBay
Rigid Fresnel Lens Sheet Magnifier Magnifying Glass | eBay
As for projection lenses I never got a good image out of conventional triplets as I could get the center or edges in focus but never both. Although more pricey I would recommend you look into copy or large photography lenses as most of them have great colour correction, cross-field focus and excellent contrast, meaning you'd do justice to the high-rez screen you're using.
I previously used a beseler 18" triplet lens in my 15.4" 1080p build which is very similar to the common OHP triplet lens (except for the size
) and then I switched over to a Rodenstock Rodagon 360mm copy lens and the difference in clarity, contrast and corner-to-corner focus definitely justified the 100 pounds I paid for it.
If you get the G3's LCD to work with some sort of controller or maybe keeping the G3's board and feeding it external video signal then please post how you did it as I'm sure a lot of people on this website would be very interested myself included.
As for the LED I suggested, the light source for this will be a bit tricky as I used a fairly compact Osram Powerball 150W metal halide bulb with my 5.6" build and found it to be way to dim even with all lights out it was only putting out around 60 Lumens but I know the LCD I used was VERY dark and didn't let much light through. As you're the first one to actually use the G3's screen you can't know if the screen is too dark and how much light it lets through. Plus I also remember reading somewhere that IPS LCDs block much more light than regular LCDs so you might get away with one of those LEDs I mentioned like the CBT90 or CBT140 or you might have to use a 250 metal halide to get a reasonable brightness out of it, but this will mean you'll then have heating problems depending on how large your box is.
This gave me an 80" image from around 2.8 meters from the screen which I found was the ideal ratio for me.
I attached an awesome calculator app that lets you play around with those distances and also gives you distances from LCD - lens, lens - fresnel, etc. This small app was created by Dazzla on the Lumenlab forums which shut down a while ago, but the thing is I couldn't get it to work on any OS higher than XP but if you can get XP this app will definitely help you.
You can also try this ALLINBOX from the awesome allinbox.com website which is in French but has loads of useful info.
I looked around for small fresnel lenses and couldn't find much. I managed to find the exact same ones I used in my old projector though.
Rigid Fresnel Lens Sheet Magnifier Magnifying Glass 163mm x 107mm (6.5" x 4") | eBay
Rigid Fresnel Lens Sheet Magnifier Magnifying Glass | eBay
As for projection lenses I never got a good image out of conventional triplets as I could get the center or edges in focus but never both. Although more pricey I would recommend you look into copy or large photography lenses as most of them have great colour correction, cross-field focus and excellent contrast, meaning you'd do justice to the high-rez screen you're using.
I previously used a beseler 18" triplet lens in my 15.4" 1080p build which is very similar to the common OHP triplet lens (except for the size
) and then I switched over to a Rodenstock Rodagon 360mm copy lens and the difference in clarity, contrast and corner-to-corner focus definitely justified the 100 pounds I paid for it.If you get the G3's LCD to work with some sort of controller or maybe keeping the G3's board and feeding it external video signal then please post how you did it as I'm sure a lot of people on this website would be very interested myself included.
As for the LED I suggested, the light source for this will be a bit tricky as I used a fairly compact Osram Powerball 150W metal halide bulb with my 5.6" build and found it to be way to dim even with all lights out it was only putting out around 60 Lumens but I know the LCD I used was VERY dark and didn't let much light through. As you're the first one to actually use the G3's screen you can't know if the screen is too dark and how much light it lets through. Plus I also remember reading somewhere that IPS LCDs block much more light than regular LCDs so you might get away with one of those LEDs I mentioned like the CBT90 or CBT140 or you might have to use a 250 metal halide to get a reasonable brightness out of it, but this will mean you'll then have heating problems depending on how large your box is.
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