Backlighting the display
July 30, 2008
Time for a much-deserved update! Been busy at work the past couple weeks and then went on vacation for the last half of last week. Back to work now!
So, the replacement LCD arrived and everything works wonderfully again. I have everything hooked up and have moved on to working on the backlight enclosure. As I posted previously, I’m using the original LCD backlight but need to add reflective walls to the sides since the backlight now sits about two feet below the display.
Right now I have begun work using styrofoam insulation sheets. They are white which means no painting and they’re very light and easy to work with. They won’t add a ton of weight to the final product. I have two walls built so far to test and see if things will work like I had thought.
Upon turning everything back on, I was very pleased to notice that this had made a huge improvement over not having any walls. However, there was still a noticeable brightness difference in the area with the backlight and the areas where the walls could be seen. It is very faint, but definitely noticeable.
I happened to have a medium-sized mirror nearby and placed it in front of the styrofoam walls to see how such a surface would look. When the looking at the display, the area with the mirror had no noticeable difference in brightness from the actual backlighting panel.
This is great news. My plan now is to buy a product called Gesso to seal the styrofoam so that I can paint it with some chrome spray paint. This should produce about the same result as the mirror without the added weight or cost of purchasing actual mirrors to use in the wall panels.
I’ll post again once more progress has been made. It should come a bit quicker this time!
Thanks for the update! Great idea with the white/chrome walls. When doing a DI setup, we used some of insulation that they put on on homes (it’s covered in a sort of metallic foil) to help bounce light around the inside of the box. I’ll be interested to see how chrome paint turns out.
One quick question: where are you planning on putting the camera? Will putting it over the backlight create a dark spot, or do you think the light reflecting around inside the box will take care of that? Just curious what your thoughts on that were.
I’m really hoping that the camera doesn’t make a dark spot. Others have said that with reflective walls the light is bright enough to diffuse the camera placed on top … but we’ll see.
If needed, I may create a couple of rails of LED lights to add to the walls and hopefully this will make even more light bouncing around above the camera.
Chrome paint didn’t work at all. It ended up being more of a silver instead of a chrome. Very disappointing. Looking now at getting foil or some other metallic material to affix to the panels.
Sounds good. Sorry to hear that the chrome paint didn’t work out for you. We’re actually getting ready to go purchase a TV ourselves and give it a go. Mostly been doing a DI setup with a projector up until this point.
If you haven’t tried the foil by the time we have, we’ll let you know how it goes
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Well what you are doing ’til now if great just want to give you suggestion not to use spray paint because it has chemicals that will destroy the styrofoam.
Good luck. I am waiting to see the final result!
Hey, just wanted to give you a quick update on progress on our end. We now have a very similar setup to yours, and for the backlight we lined the box with foiled insulation. We were able to get fairly close to even illumination, except on the edges. So, we placed a piece of tracing paper directly underneath the screen to help diffuse and even out the light. Now it looks perfect!
However, we’re running in to other problems. The backlight puts off IR light (I think I saw another post talking about this, as well). So then I thought “great, we’ll just make it DI!” But, apparently some sort of filter exists in the screen itself (the TFT part that isn’t easy to take apart), and so there is no IR light coming up through the screen.
So, then we decided to use lasers (or FTIR). However, it seems like we’re losing about 50% of the IR light on its way down through the screen to our camera.
Have you done any experimenting yet with the actual IR light? What was your plan for creating the blobs?