I've recently become re-acquainted with the joy of adding lighting to unlit handhelds, and in the process came across the seeming impossibility of backlighting a Gameboy Color screen. There's an excellent video that attempts to explain why this can't be done: But I'm not entirely satisfied with the notion that the reflector can't removed from the screen. Obviously it can't be removed easily. So in my quest to find out for myself I bought a supposedly broken GBC from eBay to experiment on. Unfortunately (or fortunately depending on how you look at it) the unit I bought for peanuts wasn't broken at all, it was just really really dirty. After scrubbing laundry soap off of the mainboard and a couple of shots of contact cleaner it was good as new. I broke the screen all the way down to get a better look at the "bottom" layer of glass to see if it could be removed. Unfortunately the ribbon cable is attached to that layer and there are several traces visible inside that layer so removing it entirely would almost definitely destroy the screen. My original intention was to split the thing apart anyway and see if the reflector and polarizer could be removed somehow, but since it was in perfect working condition I couldn't bring myself to do it. So I contacted a repair shop and asked them to sell me a defective or damaged GBC LCD. They shipped me a screen covered in rust (from the metal backing) and with a visible hole in the ribbon cable. I was not gentle removing it from the metal frame, but after I scrubbed the rust down and cleaned the ribbon cable contacts, I plugged it into a working GBC and amazingly, even with a hole in the ribbon cable it seems to work perfectly. I can't spot a single bad or stuck pixel on it. But I digress. What I'm here asking for are a couple of sanity checks before I go forward with my attempt to remove the reflector. If you have any particular knowledge that refutes or validates anything below, please let me know. Obsevations: 1. The screen is actually translucent. Holding it up to the light you can see right through it. However all that shining a light through the back accomplishes is completely washing out the screen. My suspicion is that this is the action of destructive interference and the polarization layer. To put it another way the polarization film is causing the exact opposite effect on light coming through the back - actually blocking any light that would strike the pixels. 2. There are three distinct layers of glass comprising the screen. 3. The third, or bottom/back layer is affixed to the upper layers by a visible ring of milky white adhesive that was apparently injected from a spot on the edge. Assumptions: 1. The LCD itself is contained in the upper two layers (front and middle) of glass, and the third/bottom/back layer serves the dual purpose of being an attachment panel for the LCD signal traces, and for holding the polarization and reflective film in place. 2. There are no traces running through the glass behind the reflector/polarizer. My insane plan: I'm going to mask off a section of the back layer of glass directly behind the reflective layer, etch it out with a diamond cutting tool and attempt to pull off a section of glass directly behind the LCD without damaging the LCD itself. I'm going to do this by cutting an outline and etching an X shape across the back of the screen. Then I'm going to use gorilla glue to stick a flat piece of metal (probably the short side of a PC card bracket) to one of the sections, and pull away from the screen. Hopefully it will break along the etching and not damage any of the internals of the screen itself. There are probably a million ways this could go wrong, obviously. Here are my predictions from best to worst: 1. The glass separates cleanly, the LCD is not damaged and the reflector/polarizer comes off with it, or is not adhered and can be removed without resistance. 2. The glass separates cleanly, the LCD is not damaged, but the reflector/polarizer are attached to the back of the LCD with adhesive and must be peeled off - which will probably damage the LCD. 3. The glass does not separate cleanly and the LCD traces (inside the glass) are damaged in the process. 4. The glass separates cleanly but actually contains traces running behind the reflector and thus the screen is inoperable. The most helpful piece of information going into this would be knowing which two edges actually have LCD traces attached (it's really hard to see because they seem to be completely transparent) . Constructive or cautionary commentary is welcome.
Awesome research so far! I can not help you much, but I will make sure to be following your post for progress. I have wanted a backlit gbc since always, so it's good to see someone working it!
My new DMG backlight kit finally arrived so I could take some final photos of the experiment before I go ahead and start the destructive stuff. Here's the "broken" screen attached to a working GBC in ideal reflected light - note the hole in the ribbon cable on the right. These next pics were just for the sake of completeness - I knew going into this if it was that easy someone would have done it by now, but since I hadn't seen any examples or read about anyone actually trying it, I decided to do it to be able to say I tried. Remember the screen is translucent, so we have to at least see what happens when we push light through it from the back: Here's what it looks like with the same external light as the image above: As you can tell the backlight almost completely washed the screen out and overpowers the reflected light. And here's what it looks like when you add the polarization layer behind it: Surprisingly it seems to improve the situation slightly, but it's still unusable. Here's what it looks like with the polarizer turned 90 degrees: And finally, this is what it looks like without any ambient or reflected light: If I get time today I'm going to begin very carefully trying to cut the reflective layer out of the back of the screen. Will update - I do not expect success, but at least failure won't come from lack of trying
I *think* the images should be working now. After talking it over with a couple of craft junkies at work I think I have a way to control the depth of the cut into the glass a little better and thus increase the odds of success, but sadly it will probably be a week or more before I can get all the materials together.
What happens if you dim the light of the backlight using a pot to see if that helps clean out the image while still having some light. I know not ideal but worth a little experiment.
I too am curious. Maybe even a dim backlight in addition to a dim frontlight would yield the best results...
The problem with that is that it'll probably be brighter at the bottom than at the top. Maybe you'd need some kind of diffusion layer to help spread the light.. At that point though, might as well manufacture your own (which is what the video in first post is basically saying).
Well, prior to taking those pics I experimented with other, dimmer light sources. Basically if the room is lit, the intensity of the backlight will drown out the reflected light in direct proportion. If the room is dark, the LCD activity is completely invisible with lower intensity backlight sources. There isn't really a magic fix there either.
The first attempt, as predicted, ended in failure. Thankfully it was just because I got impatient. I'll try to upload pics later on, but the short story is that I did not cut all the way through the glass before attempting to pull it apart with a powerful suction cup. The good news is that after successfully separating the bottom glass layer and seeing how it's put together I'm more optimistic that this can actually be done..
Okay, well, obviously it took me much longer to get back to this than I anticipated. Finally had time today to get everything set up and execute the plan. The short version: The second attempt also failed and I'm pretty sure now that it is not possible to remove the reflective layer without destroying the LCD, I just have a better idea now of why. The "liquid" part of the GBC Liquid Crystal Display is actually held between the second and third layers of glass - even if a section of the back layer behind the pixels could be removed without damaging the conductive paths, the LCD would no longer function because the liquid would be exposed and not stay in place. The long version: Lessons Learned There really is no such thing as cutting glass. Glass cutters actually score (scratch) the surface of the glass to create thousands of micro-fractures that weaken the glass in the right spot to be broken in a predictable and desirable way. This is not really an option when you have multiple layers of glass because each layer represents a separate structure that will be unaffected by the scoring of adjacent panes. Since glass 'cutting' is not possible in this instance, my only option was grinding. Grinding glass is REALLY dangerous because it produces a very very find dust, which if breathed in sufficient quantities can cause a very nasty and un-treatable condition called 'silicosis'. The best way to prevent glass dust is to cover the spot you're working with with a liquid to trap the particles. This also keeps the grinding element from overheating and results in a much clearer grind (dry grinding results in whitish spots - I believe because of more microfractures) The path to knowledge: During the first attempt, I had the LCD covered with oil (I used jojoba because it's a very fine oil and can stand high temperatures) so when the two layers of the LCD were separated the oil and the LCD liquid mixed and I didn't realize I had exposed the liquid layer. My plan for the second attempt was to use a diamond-tip burr bit to grind down the outline of the screen so the border was paper thin and could more easily be broken away without damaging the rest of the glass. To control the depth of the bit, I used the front part of the screen from my first attempt and locked the depth stop on my drill press to a hair's breadth above where the bit made contact. Below you can see where I've placed oil on the screen and begun drilling the corners. Once I had the corners drilled, I pushed the bit along the outline to create the "cutout" square. Unfortunately my attempt to control the depth failed and I ended up grinding all the way through. The Pic is a little blurry, but you can see the line and where the liquid crystal was exposed around it. Incidentally I reconnected it to a GBC after this happened and the darkened spot did not work at all. I wish I had taken pictures to show it, but basically that dark area was completely dead, though the rest of the screen still worked. Here's a shot of the "breach" from the other side. I was pretty sure by that point that even if I did successfully remove the back without damaging the conduits, the LCD wouldn't work anyway. With the entire outline cut down paper-thin, I decided to try to pull the back off with a suction-cup. ...and sadly, the damn thing still did not come away cleanly. But since this time the oil I was using to catch the dust had been completely removed and the outside of the LCD was completely dry when I tried to separate it, it was very obvious that what I was looking at was the liquid in the display itself. So, if this were Mythbusters, I'd say 'busted". Anyway, thanks for reading. Hope this was educational and entertaining
I think I maybe understand how that screen work. Everything is hypothetical because I wait for shipping old gbc from japan. If I'm right that means that LCD is crazy piece of science and engineering stuff.
If I only know wy that work. I assume that should work perfectly but in test is something more happening in that LCD.
