Television-makers are pitting rival technologies against each other

OVER THE decades since its invention, the goggle box has been transformed almost beyond recognition. What was once a bulky cabinet sitting in the corner of the living room has grown like Topsy in height and width and shrunk like Ant-Man in depth. The picture itself, once a blurry black-and-white image composed of scanning lines visible to the eye, is now a pin-sharp display presented in a spectrum of hues so rich than even Van Gogh would not have balked at using them. It takes only a slight stretch of the imagination to view TVs as objects more like oil paintings, better suited to hanging on a wall than sitting on the floor. And that, increasingly, is where they do hang.

Yet as good as televisions have become, they are about to get yet better. Rival makers of the two types of screen technology, one, called LED, based on liquid crystals and inorganic light-emitting diodes, the other, called OLED, on organic light-emitting diodes with no liquid crystals involved, are beautifying their offerings to the point where they are more dazzling than Lady Gaga. TVs of the future will have yet brighter images with yet higher contrast. Their screens will be bendable and may even become transparent.

Alphabet soup

All of this is driven by intense competition. At the cheap end of the market, most television-makers offer customers both LEDs and OLEDs. But at the top of their ranges they have become specialists. Samsung, a South Korean firm that is the world’s biggest television-maker, and TCL Electronics, a giant Chinese group, focus on LED models. By contrast LG, another South Korean electronics outfit, devotes its upmarket efforts to OLED. These three firms now dominate the provision of television sets, jointly accounting for more than 40% of global sales, according to IHS Markit, a research firm. And they are deadly rivals.

Despite their similar acronyms, LED sets and OLED sets work in substantially different ways. Indeed, the term LED is a bit of a misnomer for the former. The crucial parts of the screen are actually the liquid crystals. These are tiny, electronically manipulated shutters that permit or prevent the passage of light. Individual picture elements, known as pixels, consist of a trio of these shutters, each masking a filter that passes light of one of the primary colours, red, green or blue. Behind all this paraphernalia is a strong white backlight which is, indeed, generated these days by light-emitting diodes, but which was once the product of fluorescent bulbs. A pixel’s hue in an LED set is determined by how open or closed each of its shutters is, and thus what mixture of primaries gets through them.

An OLED TV, by contrast, has no backlight. Its pixels are made of organic materials that emit light when stimulated by an electric current. Different materials emit different frequencies, so different colours can be mixed in this way.

There is also one other difference. When an OLED pixel is switched off, it relaxes to a deep, dark black. Even when closed, however, the shutters of an LED system permit some of the backlight to sneak through. The result is not so much black as grey, which reduces the contrast between illuminated and unilluminated pixels.

The upshot of these various strengths and weaknesses is that LED TVs have bright, high-definition images, while pictures displayed on OLED TVs have richer colours and more contrast. Moreover, lacking a backlight, OLED TVs can be made slimmer and lighter than the LED variety. OLED screens are, however, trickier to manufacture. TVs made with them are therefore more expensive—sometimes more than twice the price of a similar sized LED television. For the customer, it is thus a matter of, “you pays your money and you takes your choice”.

One answer to the backlighting problem is to call on the services of micro LEDs. Unlike standard LEDs, these are small enough to be assembled like OLEDs into image-forming pixels. Both Samsung, in the form of a monster called The Wall, which measures 146 inches (3.7 metres) from corner to corner, and Sony, a Japanese firm, in the form of a product called Crystal LED, have micro-LED systems built from individual screen modules which can be assembled to make displays of various sizes for commercial use in places like sports stadiums. Now, though, micro-LED televisions aimed at the retail market are on their way. At this January’s Consumer Electronics Show (CES), held online rather than, as is more usually the case, in Las Vegas, Samsung unveiled a 110-inch micro-LED television constructed as a single unit. This, it says, will be the first in a new range of TVs of various sizes that will go on sale later this year. Television aficionados will, though, need deep pockets to buy one. Reports from South Korea suggest the new model will cost more than $150,000.

Quantum mechanics

That will not last long. All new electronic technologies start off being expensive in this way. When Westinghouse brought out the first colour TV in 1954 it cost $1,295, equivalent to some $12,500 today. By the 1960s colour televisions could be bought for a few hundred dollars. If new devices are successful, prices tumble as production volumes increase. Lining up 24m individually controlled micro LEDs, each only a few microns across, with the precision needed for them to work as self-illuminating pixels in such a big television screen is a tricky business. But Samsung says it has found a way of doing this, based on its production of semiconductor chips, which require similar precision.

Samsung reckons that, because micro LEDs are made of inorganic materials, they will last long enough for more than a decade of viewing. This is a dig at OLED screens. There has been some concern that the organic materials from which these are formed may deteriorate, shortening the life of a television which employs them. This was, indeed, once true. LG, though, maintains that it is no longer a problem because the manufacturing process has been refined using improved materials to make screens that are more resilient.

The logical end of this shrinkage of light-generating elements is a screen that has pixels made from quantum dots. These are tiny semiconductor particles which, if excited by light or electricity, glow in a specific colour that depends on their size. Larger dots give off light at the red end of the spectrum. Smaller ones shine blue.

Such dots are already used in some LED televisions as a layer above the backlight, an arrangement known as QLED that helps to produce brighter images and also improves contrast. Quantum dots could, though, at least in theory, be used in the way micro LEDs are, as elements of individual pixels that emit their own light directly from the screen. It is early days, but Samsung, for one, has been looking at some sort of hybrid screen which would combine quantum dots with OLEDs.

Enter the mini

Just to confuse things further, televisions called mini LEDs are also hitting the market. TCL already makes devices which employ them, and Samsung and LG have just launched their own versions.

Mini LEDS are not the same as micro LEDs. They do not produce an image but are, rather, used to improve backlighting. A standard set has a hundred or so LEDs. Mini LEDs can be packed together by the thousand. This multiplication permits different areas of the backlight to be brightened or dimmed independently of one another. The result, says Samsung, is that dark areas on the screen can be made darker and bright areas brighter, thus allowing mini-LED televisions to get even closer to rivalling the images produced by OLED sets.

LG disagrees. It reckons mini-LED TVs are limited in their ability to increase levels of contrast, and are still eclipsed by OLED televisions. To retain that advantage, LG has developed new organic materials and made other changes it is more cagey about. Because these new materials are around 20% more efficient at producing light, the firm says its OLEDs can now display even brighter and more vivid images.

That OLED TVs do not have to bother with a backlight helps with innovation of other sorts, as well. Both types of screen, if set on a plastic rather than a glass substrate, can be made pliable. But this is simpler to do with OLED screens as they have fewer layers. Hence OLEDs are the screens of choice in foldable mobile phones.

It’s showtime

Pliable screens are now spreading to televisions. At the CES, LG announced a bendable TV. Curved-screen televisions have been available for several years, but have not been successful. Such a screen may suit a single viewer, who can seat himself at the optimal point to benefit from its curvature, but it is not so great for a family looking at it from different directions. Bendable TVs get around this problem, LG says, because their screens can be curved around a single viewer (a proposition particularly appealing to some gamers) or straightened out for group audiences. Intriguingly, LG’s bendable screen can also be made to vibrate, and thus to work as a giant loudspeaker (see article).

Since they have no backlight to get in the way, OLED screens can even be made transparent—and such screens are already beginning to be deployed in shops and museums, and as see-through corporate-information boards. At the CES, LG displayed a consumer version which works as a television. The 55-inch set in question was featured at the foot of a bed, where it could be raised and lowered.

Whether that was a gimmick or a serious test of the market is not clear. LG has given no indication of when a transparent television might actually go on sale. As the television war continues, though, it is a fair bet that consumers will be in for more such treats. Since the days of John Logie Baird, the television’s inventor, manufacturers have constantly tried to outdo one another with better technology. They will continue to do so for many years to come.■