LED-backlit LCDs are not self-illuminating (unlike pure-LED systems). There are several methods of backlighting an LCD panel using LEDs, including the use of either white or RGB (Red, Green, and Blue) LED arrays behind the panel and edge-LED lighting (which uses white LEDs around the inside frame of the TV and a light-diffusion panel to spread the light evenly behind the LCD panel). Variations in LED backlighting offer different benefits. The first commercial full-array LED-backlit LCD TV was the Sony Qualia 005 (introduced in 2004),[12][13][14][15][16] which used RGB LED arrays to produce a color gamut about twice that of a conventional CCFL LCD television. This was possible because red, green and blue LEDs have sharp spectral peaks which (combined with the LCD panel filters) result in significantly less bleed-through to adjacent color channels. Unwanted bleed-through channels do not "whiten" the desired color as much, resulting in a larger gamut. RGB LED technology continues to be used on Sony BRAVIA LCD models. LED backlighting using white LEDs produces a broader spectrum source feeding the individual LCD panel filters (similar to CCFL sources), resulting in a more limited display gamut than RGB LEDs at lower cost.[citation needed]

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Mini LED displays are LED-backlit LCDs with mini-LED–based backlighting supporting over a thousand full array local dimming (FALD) zones, providing deeper blacks and a higher contrast ratio.[44] An example of a product that uses Mini LED backlighting is Apple's 2021 year 12.9 inch iPad Pro.[45]

First, some objects are just better observed in infrared wavelengths. Some bodies of matter that are cool and do not emit much energy or visible brightness, like people or a young planet, still radiate in the infrared. Humans perceive this as heat, while some other animals, like snakes, are able to “see” infrared energy.

Full-array mini-LED backlights, consisting of several thousand WLEDs, were being researched for TVs and mobile devices in 2017.[36]

Infraredwavelength

A small full-color illustration of the Earth, which is labeled in white text, appears at far left. From the Earth, a dark purple triangle begins, slowly enlarging toward the right to cover the area where a small illustration of the James Webb Space Telescope appears and a long, wavy multicolored line. The purple triangle blends into the black background as it becomes taller toward the right.

The white LEDs in LED backlights may use special silicate phosphors, which are brighter but degrade faster.[37] The size of the LEDs is one of the factors that determines the size of the bezel of LED-backlit LCDs.[38]

infraredradiation中文

This homogeneous backlight is ideal for inspecting and measuring outlines. The lateral coupling of the LED light ensures a very homogeneous radiation over the ...

Midinfrared

Additionally a special diffusion panel (light guide plate, LGP) is often used to spread the light evenly behind the screen.

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Visible light’s short, tight wavelengths are prone to bouncing off dust particles, making it hard for visible light to escape from a dense nebula or protoplanetary cloud of gas and dust. The longer wavelengths of infrared light slip past dust more easily, and therefore instruments that detect infrared light—like those on Webb—are able to see the objects that emitted that light inside a dusty cloud. Low-energy brown dwarfs and young protostars forming in the midst of a nebula are among the difficult-to-observe cosmic objects that Webb can study. In this way, Webb will reveal a “hidden” universe of star and planet formation that is literally not visible.

Infrared light

A first dynamic "local dimming" LED backlight was public demonstrated by BrightSide Technologies in 2003,[33] and later commercially introduced for professional markets (such as video post-production).[34] Edge LED lighting was first introduced by Sony in September 2008 on the 40-inch (1,000 mm) BRAVIA KLV-40ZX1M (known as the ZX1 in Europe). Edge-LED lighting for LCDs allows thinner housing; the Sony BRAVIA KLV-40ZX1M is 1 cm thick, and others are also extremely thin.[citation needed]

Televisions that use a combination of an LED backlight with an LCD panel are sometimes advertised as LED TVs, although they are not truly LED displays.[1][2]

The prismatic and reflective polarization films are generally achieved using so called DBEF films manufactured and supplied by 3M.[30][31] These reflective polarization films using uniaxial oriented polymerized liquid crystals (birefringent polymers or birefringent glue) were invented in 1989 by Philips researchers Dirk Broer, Adrianus de Vaan and Joerg Brambring.[32]

Safety lens tint for enhanced contrast These amber shooting glasses are commonly used during shooting, hunting, and target practice.

... Figure 1: UV and visible light spectrum with UV classifications ... UV-B or a combination of both to achieve their target effect. If a ...

Backlit LCDs cannot achieve true blacks for pixels, unlike OLED and microLED displays. This is because even in the "off" state, black pixels still allow some light from the backlight through. Some LED-backlit LCDs use local dimming zones to increase contrast between bright and dim areas of the display, but this can result in a "blooming" or "halo" effect on dark pixels in or adjacent to an illuminated zone.[3]

LED-backlit LCDs have longer life and better energy efficiency than plasma and CCFL LCD TVs.[35] Unlike CCFL backlights, LEDs do not use mercury in their manufacture, which is an environmental pollutant. However, other elements (such as gallium and arsenic) are used in the manufacture of the LED emitters; there is debate over whether they are a better long-term solution to the problem of screen disposal.[citation needed]

The rainbow of light that the human eye can see is a small portion of the total range of light, known in science as the electromagnetic spectrum. Telescopes can be engineered to detect light outside the visible range to show us otherwise hidden regions of space. The James Webb Space Telescope detects near-infrared and mid-infrared wavelengths, the light beyond the red end of the visible spectrum.

An LED-backlit LCD is a liquid-crystal display that uses LEDs for backlighting instead of traditional cold cathode fluorescent (CCFL) backlighting.[1] LED-backlit displays use the same TFT LCD (thin-film-transistor liquid-crystal display) technologies as CCFL-backlit LCDs, but offer a variety of advantages over them.

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Infrared light reveals new details in images, deepening our understanding of celestial objects. For more exploration of what we can learn from other wavelengths, visit NASA’s Universe of Learning ViewSpace Interactives.

Wavelengths for which the index of refraction is n + δn, where δn << n, are refracted at angle θ₂ + δθ. b. A beam of white light is incident on a piece of glass ...

Infraredspectroscopy

A 2016 study by the University of California (Berkeley) suggests that the subjectively perceived visual enhancement with common contrast source material levels off at about 60 LCD local dimming zones.[11]

Above each segment is a sine wave pattern indicating the relative wavelength of the band. The sine wave patterns are oriented vertically. The wavelengths increase from left to right. The wave pattern above Gamma is tightest (shortest wavelength). The wave pattern above Radio is more extended (longest wavelength).

The combination of LED dynamic backlight control[18] in combination with reflective polarizers and prismatic films (invented by Philips researchers Adrianus de Vaan and Paulus Schaareman[27] make these "LED" (LCD) televisions far more efficient than the previous CRT-based sets, leading to a worldwide energy saving of 600 TWh in 2017, equal to 10% of the electricity consumption of all households worldwide, or twice the energy production of all solar cells in the world.[28][29]

LED backlights are often dimmed by applying pulse-width modulation to the supply current, switching the backlight off and on more quickly than the eye can perceive. If the dimming-pulse frequency is too low or the user is sensitive to flicker, this may cause discomfort and eyestrain similar to the flicker of CRT displays at lower refresh rates.[46] This can be tested by simply waving a hand in front of the screen; if it appears to have sharply-defined edges as it moves, the backlight is pulsing at a fairly low frequency. If the hand appears blurry, the display either has a continuously-illuminated backlight or is operating at a frequency too high to perceive. Flicker can be reduced (or eliminated) by setting the display to full brightness, although this can degrade image quality and increases power consumption.[citation needed]

Observation of these early days in the universe’s history will shed light on perplexing questions of dark matter and energy, black holes, galaxy evolution over time, what the first stars were like, and how we arrived at the universe we experience today.

Quantum dots are photoluminescent; they are useful in displays because they emit light in specific, narrow normal distributions of wavelengths. To generate white light best suited as an LCD backlight, parts of the light of a blue-emitting LED are transformed by quantum dots into small-bandwidth green and red light such that the combined white light allows a nearly ideal color gamut to be generated by the RGB color filters of the LCD panel. The quantum dots may be in a separate layer as a quantum dot enhancement film, or replace pigment-based green and red resists normally used in LCD color filters. In addition, efficiency is improved, as intermediate colors are no longer present and do not have to be filtered out by the color filters of the LCD screen. This can result in a display that more accurately renders colors in the visible spectrum. Companies developing quantum dot solutions for displays include Nanosys, 3M as a licensee of Nanosys, QD Vision of Lexington, Massachusetts, US and Avantama of Switzerland.[39][40] This type of backlighting was demonstrated by various TV manufacturers at the Consumer Electronics Show 2015.[41] Samsung introduced their first 'QLED' quantum dot displays at CES 2017 and later formed the 'QLED Alliance' with Hisense and TCL to market the technology.[42][43]

The evolution of energy standards and the increasing public expectations regarding power consumption made it necessary for backlight systems to manage their power. As for other consumer electronics products (e.g., fridges or light bulbs), energy consumption categories are enforced for television sets.[21] Standards for power ratings for TV sets have been introduced, e.g., in the US, EU, Australia,[22] and China.[23] A 2008 study[24] showed that among European countries power consumption is one of the most important criteria for consumers when they choose a television, as important as the screen size.[25]

The diagram includes a horizontal bar consisting of seven labeled segments representing seven different bands of the electromagnetic spectrum. From left to right these are: Gamma, X-Ray, Ultraviolet, Visible, Infrared, Microwave, and Radio. Gamma, X-ray, Microwave, and Radio segments are all colored in shades of gray. The Ultraviolet segment is various shades of purple. The Infrared segments is shades of red and orange. The Visible segment is rainbow, from purple on the left to red on the right.

near-infraredlight

Lightpath definition: A section of an optical network in which light travels without being modified.

At the bottom of the graphic, there is a thin yellow bar. It includes several labels. Below Earth, but before the telescope illustration appears, the label reads “24 M L-Ys” (or light-years). A blue vertical line appears over the yellow bar just below the telescope illustration above.

InfraredWaves

LED backlights replace CCFL (fluorescent) lamps with a few to several hundred white, RGB or blue LEDs. An LCD with LED-Backlight may be edge- or direct-lit:[9]

Just past this section of the third yellow label, on the far right, there is a dotted half circle. To the right of the dotted half circle are more than a dozen small circles with dots at the center that represent galaxies. They appear in various shades of blue, purple, and pink. No two are the same, though all appear significantly smaller than Earth or Webb at left.

Below the wavelength bar are line sketches of three telescopes, labeled with the telescope name and wavelength range. From left to right: The Hubble Space Telescope has a wavelength range of 90 to 2,500 nanometers, corresponding to the right-most portion of the Ultraviolet segment, all of the Visible, and the left-most sliver of the Infrared segment. The James Webb Space Telescope has a wavelength range of 600 to 28,500 nanometers, corresponding to a sliver of red visible light and the left half of the Infrared segment. The Spitzer Space Telescope has a wavelength range of 3,000 to 160,000 nanometers, corresponding to the right half of the Infrared segment.

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This video begins in visible light and ends with an image in infrared light. Note what each wavelength reveals and conceals. Get video details and downloads in the Video gallery, or download video captions (no audio, VTT), and transcript of the audio description (Word Doc, 19 KB). Credit: NASA, ESA, G. Bacon (STScI).

Using PWM (pulse-width modulation), a technology where the intensity of the LEDs are kept constant but the brightness adjustment is achieved by varying a time interval of flashing these constant light intensity light sources,[26] the backlight is dimmed to the brightest color that appears on the screen while simultaneously boosting the LCD contrast to the maximum achievable levels, drastically increasing the perceived contrast ratio, increasing the dynamic range, improving the viewing angle dependency of the LCD and drastically reducing power consumption.[clarification needed]

Because LEDs can be switched on and off more quickly than CCFLs and can offer a higher light output, it is theoretically possible to offer very high contrast ratios. They can produce deep blacks (LEDs off) and high brightness (LEDs on). However, measurements made from pure-black and pure-white outputs are complicated by edge-LED lighting not allowing these outputs to be reproduced simultaneously on screen.[clarification needed]

Finally, infrared light holds clues to many mysteries from the beginning of everything, the first stars and galaxies in the early universe, after the big bang. Through a process called cosmological redshifting, light is stretched as the universe expands, so light from stars that is emitted in shorter ultraviolet and visible wavelengths is stretched to the longer wavelengths of infrared light.

infrared中文

The local dimming method of backlighting allows to dynamically control the level of light intensity of specific areas of darkness on the screen, resulting in much higher dynamic-contrast ratios, though at the cost of less detail in small, bright objects on a dark background, such as star fields or shadow details.[10]

A wavy line begins at the mirrors of the telescope and extends horizontally to the right side of the graphic to the location of the galaxies. The line appears red, with longer waves at left. It slowly changes into orange and yellow, and the waves become tighter. As the colors of the waves change to green and blue, the waves appear even tighter. As the line becomes purple, the waves are the closest to one another. This line is labeled “Light redshifted (stretched) by expansion of space.”

Infographic titled “Electomagnetic Spectrum” comparing the wavelengths of light that can be detected by the Hubble, Webb, and Spitzer space telescopes.

WhiteOptics offers a variety of optical products that can collimate, focus and guide light so designers have ultimate control on how to direct the light.

Television sets described as "LED TVs" are LCD-based, with the LEDs dynamically controlled using the video information[17] (dynamic backlight control or dynamic "local dimming" LED backlight, also marketed as HDR, high dynamic range television, invented by Philips researchers Douglas Stanton, Martinus Stroomer and Adrianus de Vaan[18][19][20]

Where the small telescope appears through about a third of the width of the graphic, the label reads “24 – 100 million light-years.” Approximately where this label ends, just about a third of the way across the overall graphic, is a second vertical blue line.