How can I convert a transmissive to a reflective LCD screen?

Hello everyone,

So basically a reflective LCD screen is one that has no backlight, and reflects ambient light off a type of mirror reflector, to allow the image on the LCD to be seen via reflection. An example of a reflective LCD screen is the Gameboy Advance's LCD screen.

A transmissive LCD is one that has a backlight that transmits light, but does not reflect light. These are typically 99.99% of the screens out there, such as PC Monitors, Smartphone screens, etc...

Now I would like to know how to turn a Transmissive LCD screen, into a Reflective screen, like the GBA screen, without the need for a backlight. The reason I ask this is because I need it for outdoor use (to be sunlight readable), and backlights can't compete with the sun, and having a strong backlight drains battery.

I have done a lot of research on this, but can't wrap my head around how the GBA screen works.

I have removed the backlight off my computer LCD screen, and added a reflective film beneath the rear polarizer on the LCD screen, but it obviously doesn't make it reflective. I'm obviously missing a crucial step.

Is the reflective film in the GBA, 'sandwhiched' somewhere in between the actual LCD screen?

Does anyone know how to make a Transmissive LCD computer monitor, into a Gameboy Advance Reflective Screen?

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freemerk1 month ago

Any news? I would like to do the same. Serch for a reddit pst explaining how gba screen works if you haven't found out yet.

gmoon1 year ago

Think of the difference between a photographic print, and a photographic transparency (commonly called a slide). Yeah, these are pretty retro concepts, I know.

The transparency works when you shine light through it from the opposite side of the viewer. For a print, light passes through the image twice: once through to the reflective background, is reflected, then passes through again back to the viewer.

Back many moons ago when I worked with a 4x5 (inch) view camera, I noted that really overexposed transparencies (I.E., super light, very thin) could be placed on a sheet of paper and they'd look exactly like a correct print.

Toga_Dan1 year ago

if you backlight the screen right now (with a flashlight, bare bulb, etc, can you see the info on the screen

davidwinst (author)  Toga_Dan1 year ago

Yes, of course. Even if I hold it up to sunlight, the screen is visible as normal. I just don't know how to make it reflective like the GBA screen. I tried adding a mirror behind the rear polarizer, but nothing is reflected.

I must be missing a crucial point that I just don't know about.

Is the mirror supposed to be behind the rear polarizer, or sandwhiched between the actual TN LCD screen?

I would think reflector behind everything.

Try the frosted side of aluminum foil. Careful not to short anything out. Try as many things as you can. Paper, tracing paper, mylar, etc. My guess is that being pressed firmly against the display is important. Use soft foam to do this.

If a dozen attempt fail, and one works, you suceeded. Share what u learned.
davidwinst (author)  Toga_Dan1 year ago

Yes, I already tried that, and yes I did manage to short it out, and now one of my green chip thingies does not work anymore. The Aluminum foil seems to reflect light, but not sufficiently to make anything on the screen readable, when compared to one of my Transflective displays (which has the backlight off).

I'm thinking of just opening up one of my Transflective LCD displays, because I still don't quite understand how light reflection works, and seeing exactly how it works. If I manage to find out how it works, and if it is doable, I may be able to swap out the Transflective film with a Reflective film, so it reflects all ambient light. Or better yet, just convert a regular Transmissive LCD to a Reflective LCD.

davidwinst (author)  davidwinst1 year ago

Or do I need an LCD screen that only has one polarizer, such as an IPS, VA, MVA, etc, screen? Because it seems that TN 'normally white' screens have 2 polarizers that only allow light between them, whereas IPS, VA or other 'normally black' screens only have one polarizer (according to other websites). But do they have one polarizer at the front, or at the rear of the display? I'm thinking of just purchasing a cheap IPS or VA screen to test this out, and see whether they truly only have 1 polarizer.

The problem is with the physics.
The two polarizers of a "normal" screen won't allow for any visible light to be reflected as the polarised lights cancell each outher out.
Only if the polarizer films are constructed or located on the back of the display you can see things on the screen.
A "workaround" these limitations (as it is next to impossible to remove the polarizer without damage) would be to use a light transmissive panel to catch the surrounding light and use it as a backlight.
Simlilar to how the light panels for big buildings work: Big acrylic sheets "catch" the light but as it mostly comes out the thin sides it can be directed onto a suitable sheet that transmits light towards the display, like the diffusors used on some TV screens.
If you take a big screen apart you'll notice several seemingly useless sheets of white or opaque plastic - they disperse the light evenly onto the display.

davidwinst (author)  Downunder35m1 year ago

I had removed both the front and back polarizer films on another TN LCD display, without damaging the LCD display, but still don't know where to add the reflective film, as all that is left is the LCD display which seems to be made up of 2 layers.

Yes, those sheets of diffused white plastic absorb and disperse light evenly, and by using those sheets you can see the LCD screen in broad daylight just like it has a backlight. It looks identical to a backlit screen.

The only problem with that is, on a bright sunny day, the screen is so bright, that it causes your eyes to bleed. It really hurts. Yes, I've tried it already, and it isn't feasible. It's like having a backlight the equivalent strength of the sun.

Do you have any other ideas in regards to making a reflective display like the GBA? Nintendo has stated that their reflective displays were cheap to make, so they used them, while other people say that reflective displays or even transflective displays are expensive to make, which I don't believe to be true.

If it too bright you can always add a filter of sorts.
The problem with reflective screens is that they need amient light to be visible.
But if the light is too much the display acts like a mirror.

The polarizing sheets are needed to make the LCD visible, without them you would need polarized sunnies to see what is happening on the screen.
And as you already noticed it not really easy to get things right so it would work in all light conditions.

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