Jan 25, 2021 11:27 PM
https://www.economist.com/science-and-te...each-other
EXCERPTS: . . . 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 tarting up their offerings to the point where they are more dazzling than Lady Gaga [...]
All of this is driven by intense competition. [...] 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 backlighting. Its pixels are layers of organic materials that emit light of their own when stimulated by an electric current. Different organic materials emit light of 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...
One answer to the backlighting problem is to introduce pixels assembled from so-called micro LEDs. Unlike standard LEDs, these are small enough to be placed in the screen to emit lightly directly, like OLEDs. [...] micro-LED televisions aimed at the retail market are on their way ... Reports from South Korea suggest the new [110-inch] model will cost more than $150,000.
That will not last long. All new electronic technologies start off being expensive in this way. [...] 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... (MORE - details)
EXCERPTS: . . . 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 tarting up their offerings to the point where they are more dazzling than Lady Gaga [...]
All of this is driven by intense competition. [...] 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 backlighting. Its pixels are layers of organic materials that emit light of their own when stimulated by an electric current. Different organic materials emit light of 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...
One answer to the backlighting problem is to introduce pixels assembled from so-called micro LEDs. Unlike standard LEDs, these are small enough to be placed in the screen to emit lightly directly, like OLEDs. [...] micro-LED televisions aimed at the retail market are on their way ... Reports from South Korea suggest the new [110-inch] model will cost more than $150,000.
That will not last long. All new electronic technologies start off being expensive in this way. [...] 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... (MORE - details)