Led tvs how do they work

Unfortunately, there was no way to avoid eventual burn-in, and almost every plasma TV suffered from it. OLED TVs have similar characteristics to plasmas with their infinite contrast ratio, wide viewing angles, near-instant response time, and to a lesser extent, the risk of permanent burn-in. An LCD screen is composed of two parts: the actual liquid crystal display and a light source at the back of the screen called backlight. A light diffuser is placed between the backlight and the LCD screen to make the source of light uniform across the screen.

The LCD panel doesn't emit light by itself, and this is why it needs a backlight; it only acts as a filter to block the light on a per-pixel basis. The backlight is always on, and the pixels in the display rotate to allow light through, creating the colors needed for the image. If the screen wants to display black, the LCD pixels rotate to try to block the light completely.

If it wants to display white, it lets all light through. Since the display is only a filter, the blacks will not be as deep as with a plasma screen because an LCD panel will always let a small portion of light through. There are different types of LCD panels, each with its unique characteristics.

Vertical Alignment VA panels generally have a high contrast ratio and narrow viewing angles, while In-Plane Switching IPS panels have a low contrast ratio with wide viewing angles. You can read about their differences here.

The backlight is a series of light tubes placed behind the screen. These tubes are very similar to fluorescent lamps used in buildings but smaller. Also, LED TVs have more control over their backlight, resulting in vivid colors and better picture quality.

There are three main configurations of LED as backlights for television screens: full-array, edge-lit, and direct-lit. This method is considered the best LED backlight type and is usually found on higher-end models, but as of , some mid-range models have it too. This produces a more uniform backlight and provides more effective use of local dimming , where it can turn off and dim complete zones of LEDs.

Depending on the display, it can be all around the screen, on the left and right sides, or at the top and bottom. This allows the screen to be very thin. However, it can cause some spots on the screen to be brighter than others, like the edges.

This problem is called flashlighting or clouding. It can be seen when watching a dark scene in a dark environment. Also, edge-lit screens usually don't result in good local dimming as they don't have control over the dimming zones.

Like the full-array method, the LEDs are directly behind the screen. However, there are very few of them, and they can't be controlled separately to match the luminosity of the picture. This allows for more lights, creating a brighter image and more control over local dimming. Only a handful of Mini LED TVs were produced before , but it now seems that manufacturers are starting to use the technology more often. Another technology, Micro LED, is only in its initial phases of development.

Plasma and LCD each present advantages and disadvantages when it comes to picture quality. Plasma TVs generally offer better contrast, wider viewing angles, and improved response times, while LCD TVs get much brighter and have better reflection handling. LCDs also cost less and can be much thinner, which are two of the main reasons why they took over the market share from plasmas in the mids.

Get insider access. Best TVs. TV Recommendations. In a plasma television, little cells of noble gases, usually Neon and Xenon, are excited and get into a supercharged state known as the plasma state. In this state, the subatomic components of these gases emit ultraviolet light. The ultraviolet light itself is not visible. However, there are little phosphors inside those cells that absorb this ultraviolet light and then re-emit it as light in the visible spectrum.

That is what you eventually see as the viewer of the television. Within each pixel, there are 3 smaller pixels that each emit red, blue, or green light.

For brighter light, the gas is excited to a higher degree. Meanwhile, these three colors combine in different proportions to produce all the colors you see on your television. Because of the nature of light production, the pixels are excited in little bursts of power, which causes them to flicker. In the early days of plasma display technology, this flickering was visible to the naked eye and affected the user experience.

On higher end models the flickering happens much faster, which reduces the effect. One of the strengths of plasma display technology is how deep the blacks are. This is mainly because each pixel individually emits its own light. For black to be displayed , the pixels in the associated area will simply not emit any light at all. The pixels also stop emitting light as soon as the excitement stops, which makes images change more smoothly.

This is another advantage that plasma displays have over LCD displays, which often suffer from motion blur. One major disadvantage of plasma displays is image retention, which occurs when the same image has been on the plasma display for a long time. Technology has improved the situation and, while image retention still occurs, it rarely lasts for more than a few minutes, unless the image has been on display for many days at a time a problem more common among public advertisement displays.

Full-array backlighting swaps the outdated CCFLs for an array of LEDs spanning the back of the screen, comprising zones of LEDs that can be lit or dimmed in a process called local dimming. While there are some drawbacks to edge lighting compared to full-array or direct backlight displays, the upshot is edge lighting that allows manufacturers to make thinner TVs that cost less to manufacture.

To better close the local-dimming quality gap between edge-lit TVs and full-array back-lit TVs, manufacturers like Sony and Samsung developed their own advanced edge lighting forms.

These keep the slim form factor achievable through edge-lit design and local dimming quality more on par with full-array backlighting.

This is accomplished by selectively dimming the LEDs when that particular part of the picture — or region — is intended to be dark. The quality of local dimming varies depending on which type of backlighting your LCD uses, how many individual zones of backlighting are employed, and the quality of the processing. TVs with full-array backlighting have the most accurate local dimming and therefore tend to offer the best contrast. Since an array of LEDs spans the entire back of the LCD screen, regions can generally be dimmed with more finesse than on edge-lit TVs, and brightness tends to be uniform across the entire screen.

Because edge lighting employs LEDs positioned on the edge or edges of the screen to project light across the back of the LCD screen, as opposed to coming from directly behind it, it can result in very subtle blocks or bands of lighter pixels within or around areas that should be dark. It should also be noted that not all LED edge-lit TVs offer local dimming, which is why it is not uncommon to see glowing strips of light at the edges of a TV and less brightness toward the center of the screen.

This is especially noticeable in scenes with high contrast, as the dark portions of the picture may appear too bright or washed out. An OLED display uses a panel of pixel-sized organic compounds that respond to electricity.