Transparent TVs Are Here and How They Work Is Fascinating

At CES in January, both LG and Samsung showed off transparent TVs. These seemingly magical devices can show an image just like a regular TV, except you can also see right through them. Images seem to float in the air. When off, they seem like they're part of the furniture. 

For home use, these will almost certainly just be the toys of the ultrarich for the foreseeable future. You're likely going to see transparent displays out in the wild in a variety of commercial settings. They can be used to add more info about what you're seeing through it, add advertising while remaining generally clear, enable more engaging teleconferencing, and more. 

At this point, you're probably wondering, as I certainly did, how? How can you make a TV transparent? Don't you need wires and stuff? How do the pixels disappear enough to be able to see through the TV? Is there a performance penalty for this magic? While neither LG nor Samsung have offered up much info, we spoke to Jacky Qiu from OTI Lumionics which has been working on these displays for years, most recently with LG. Here's what we found out. 

Sadly, not literally magic

In some ways, transparent TVs are remarkably similar to their non-transparent elders. There are new technologies needed to make these work, but in many ways, it's more evolution than revolution.

To start, let's discuss a few basic things that are needed to display a picture on any TV. To begin with, you need something that can create an image, and this starts with the pixel. Pixels, which are a portmanteau of "picture elements," do vary slightly depending on the TV's technology. OLED TVs, for instance, are a stack of organic elements that emit light when supplied with electricity. With MicroLED, it's a similar stack but of a different material. There's also LED LCD, which comprises the vast majority of TVs on the market, but that tech isn't used in transparent TVs so we'll skip that. You can learn more about them all in general in our OLED vs. LED vs. MiniLED vs. LCD: What's the Best? article. 

Beyond the pixels, you also need a way to get electricity to the pixels. You need to be able to tell each pixel when and how bright to be to create an image. For simplicity we'll just refer to the pixel as a whole, just know that each pixel is three (or sometimes four) sub-pixels that each create red, green, blue and sometimes white. To oversimplify, you can think of all these wires used to address each pixel like a massive game of Battleship. If you need a specific pixel to light up, the TV's processor calls out the equivalent of "E6" and the pixel at the "E6" location lights up. It's vastly more complicated and happens thousands of times a second over the millions of pixels in a TV, but that's the general idea. 

The challenge, as far as transparent TVs are concerned, is neither the pixels nor the wires, are, you know, transparent. Quite the opposite. So two things had to happen before transparent TVs were possible. You might be thinking "uh, make the pixels clear?" That's sort of right, but not exactly. They had to get brighter. By making them brighter, the light-emitting part of the pixel could be smaller while maintaining the same, or at least similar brightness. The bigger challenge is making the wires and other parts of the pixel transparent. 

Nearly every wire you've ever touched is either copper, aluminum, or some combination of those. They're obviously opaque and solid. Not just an invention of Star Trek's Commander Scott, transparent aluminum is a real thing but in TV's case it's not that helpful. Instead, materials such as indium tin oxide (also used in touchscreens) allow the current to flow while being essentially clear. 

So with the wires largely out of sight, and making the light-emitting portions of the pixels smaller, the space around the pixels is now available to let light pass through. That's the big trick. Transparent TVs aren't "clear," more "clear-ish." The panels are a very fine mesh. Imagine standing some distance from a screen door. You can see through it perfectly well, but if you get close, you can see the wires. This is the case with transparent TVs. If you get really close, like with a microscope (as in the image directly above), you'll be able to see the pixels. The pixels themselves are smaller than you'd find in a similarly sized normal TV, with larger gaps between them. 

That leaves the rest of the TV. Behind the screen of a normal TV, there are inputs, circuit boards and so on. These can be placed below the screen, like in LG's discontinued and commercial 55EW5F-A, or in a separate external unit connected with a cable. Then it's just a matter of removing the opaque back panel, and the result looks like magic.

The last step for home use is some mechanism to revert all that and make the TV not transparent so you can watch a TV show as normal. That's the big issue. No TV can "create" black. On a transparent TV anything that's supposed to be black is clear. Not exactly what you want when you're just trying to enjoy your 8th rewatch of The Expanse (which incidentally has transparent displays for all the hand terminal "cell phones" and tablets). The LG prototype from CES, for example, had a retractable anti-reflector that converts the transparent TV into a normal TV by rolling up a black screen behind it.

The clear-adjacent future

This all makes it sound significantly easier than it is. That's why transparent TVs are going to be very expensive for the foreseeable future. Other than being undeniably cool, and an easy conversation piece, I don't think most people will want an expensive transparent TV at home anyway. Beyond the price, the other issue is performance. No matter how bright the pixels get in a transparent TV, they're always going to be worse performing than a non-transparent TV using the same technology. Those undersized pixels? The full-size version is going to be way brighter, which means the regular TV is going to be brighter and therefore have a better contrast ratio.

Home use will probably be one of the least common uses of transparent displays. There are the commercial possibilities mentioned above, as well as windows that offer weather or other info about the view beyond, windshields that show speed and GPS directions, store displays that have product names and prices, and more. In the last few years, there have been some vehicles with small transparent displays as a heads-up display, but that older tech is too dark to use across an entire windshield.

The structure of a transparent TV is more akin to a phone display than a TV, so it's not surprising we've already seen some phones with this feature. In this use case, the whole screen isn't transparent, just a portion, under which is a camera. No more notches or cutouts in the screen, just an edge-to-edge screen hiding a selfie camera and potentially more. Imagine a laptop screen where, during a Zoom meeting, you can look right at the person's face and have them see you looking right at them and not down at your computer. There are some serious design challenges to making this work while maintaining image quality, so it will be interesting to see how this develops.

As far as home use goes, in the short term, these will just be toys for rich people. Perhaps in rooms that don't have their 200-inch MicroLED walls. For the rest of us, the transparent future at home will roll out more slowly, but much faster out in the corporate wilds.

As well as covering audio and display tech, Geoff does photo tours of cool museums and locations around the world, including nuclear submarines, aircraft carriers, medieval castles, epic 10,000-mile road trips and more.

Also check out Budget Travel for Dummies, his travel book and his bestselling sci-fi novel about city-size submarines. You can follow him on Instagram and YouTube.