is the backlight part of the lcd screen brands

2023-01-03 12:32:11

This article is about backlights in liquid crystal displays. For the rear window of an automobile, see Car glass. For the lighting design practice, see Backlighting (lighting design). For other uses, see Backlight (disambiguation).

A backlight is a form of illumination used in liquid crystal displays (LCDs). As LCDs do not produce light by themselves—unlike, for example, cathode ray tube (CRT), plasma (PDP) or OLED displays—they need illumination (ambient light or a special light source) to produce a visible image. Backlights illuminate the LCD from the side or back of the display panel, unlike frontlights, which are placed in front of the LCD. Backlights are used in small displays to increase readability in low light conditions such as in wristwatches,smart phones, computer displays and LCD televisions to produce light in a manner similar to a CRT display. A review of some early backlighting schemes for LCDs is given in a report Engineering and Technology History by Peter J. Wild.

Simple types of LCDs such as in pocket calculators are built without an internal light source, requiring external light sources to convey the display image to the user. Most LCD screens, however, are built with an internal light source. Such screens consist of several layers. The backlight is usually the first layer from the back. Light valves then vary the amount of light reaching the eye, by blocking its passage in some way. Most use a fixed polarizing filter and a switching one, to block the undesired light.

An ELP gives off uniform light over its entire surface, but other backlights frequently employ a diffuser to provide even lighting from an uneven source.

Backlights come in many colors. Monochrome LCDs typically have yellow, green, blue, or white backlights, while color displays use white backlights that cover most of the color spectrum.

Colored LED backlighting is most commonly used in small, inexpensive LCD panels. White LED backlighting is becoming dominant. ELP backlighting is often used for larger displays or when even backlighting is important; it can also be either colored or white. An ELP must be driven by relatively highAC power, which is provided by an inverter circuit. CCFL backlights are used on larger displays such as computer monitors, and are typically white in color; these also require the use of an inverter and diffuser. Incandescent backlighting was used by early LCD panels to achieve high brightness, but the limited life and excess heat produced by incandescent bulbs were severe limitations. The heat generated by incandescent bulbs typically requires the bulbs to be mounted away from the display to prevent damage.

For several years (until about 2010), the preferred backlight for matrix-addressed large LCD panels such as in monitors and TVs was based on a cold-cathode fluorescent lamp (CCFL) by using two CCFLs at opposite edges of the LCD or by an array of CCFLs behind the LCD (see picture of an array with 18 CCFLs for a 40-inch LCD TV). Due to the disadvantages in comparison with LED illumination (higher voltage and power needed, thicker panel design, no high-speed switching, faster aging), LED backlighting is becoming more popular.

LED backlighting in color screens comes in two varieties: white LED backlights and RGB LED backlights.blue LED with broad spectrum yellow phosphor to result in the emission of white light. However, because the spectral curve peaks at yellow, it is a poor match to the transmission peaks of the red and green color filters of the LCD. This causes the red and green primaries to shift toward yellow, reducing the color gamut of the display.a red, a blue, and a green LED and can be controlled to produce different color temperatures of white. RGB LEDs for backlighting are found in high end color proofing displays such as the HP DreamColor LP2480zx monitor or selected HP EliteBook notebooks, as well as more recent consumer-grade displays such as Dell"s Studio series laptops which have an optional RGB LED display.

RGB LEDs can deliver an enormous color gamut to screens.additive color) the backlight can produce a color spectrum that closely matches the color filters in the LCD pixels themselves. In this way, the filter passband can be narrowed so that each color component lets only a very narrow band of spectrum through the LCD. This improves the efficiency of the display since less light is blocked when white is displayed. Also, the actual red, green, and blue points can be moved farther out so that the display is capable of reproducing more vivid colors.

A newNanosys, claims that the color output of the dots can be tuned precisely by controlling the size of the nanocrystals. Other companies pursuing this method are Nanoco Group PLC (UK), QD Vision, 3M a licensee of Nanosys and Avantama of Switzerland.Sony has adapted Quantum Dot technology from the US company QD Visionedge-lit LED backlight marketed under the term Triluminos in 2013. With a blue LED and optimized nanocrystals for green and red colors in front of it, the resulting combined white light allows for an equivalent or better color gamut than that emitted by a more expensive set of three RGB LEDs. At the Consumer Electronics Show 2015, Samsung Electronics, LG Electronics, the Chinese TCL Corporation and Sony showed QD-enhanced LED-backlighting of LCD TVs.

CCFL backlighting has also improved in this respect. Many LCD models, from cheap TN-displays to color proofing S-IPS or S-PVA panels, have wide gamut CCFLs representing more than 95% of the NTSC color specification.

There are several challenges with LED backlights. Uniformity is hard to achieve, especially as the LEDs age, with each LED aging at a different rate. Also, the use of three separate light sources for red, green, and blue means that the white point of the display can move as the LEDs age at different rates; white LEDs are also affected by this phenomenon, with changes of several hundred kelvins being recorded. White LEDs also suffer from blue shifts at higher temperatures varying from 3141K to 3222K for 10 °C to 80 °C respectively.Benq G2420HDB consumer display has a 49W consumption compared to the 24W of the LED version of the same display (G2420HDBL).

To overcome the aforementioned challenges with RGB and white LED backlights an "advanced remote phosphor" cockpit displays,Air Traffic Control displays and medical displays. This technology uses blue pump LEDs in combination with a sheet on which phosphorous luminescent materials are printed for colour conversion. The principle is similar to Quantum Dots, but the phosphors applied are much more robust than the quantum dot nano-particles for applications that require long lifetime in more demanding operational conditions. Because the phosphor sheet is placed at a distance (remote) of the LED it experiences much less temperature stress than phosphors in white LEDs. As a result, the white point is less dependent on individual LEDs, and degrading of individual LEDs over lifetime, leading to a more homogenous backlight with improved colour consistency and lower lumen depreciation.

The use of LED backlights in notebook computers has been growing. Sony has used LED backlights in some of its higher-end slim VAIO notebooks since 2005, and Fujitsu introduced notebooks with LED backlights in 2006. In 2007, Asus, Dell, and Apple introduced LED backlights into some of their notebook models. As of 2008Lenovo has also announced LED-backlit notebooks. In October 2008, Apple announced that it would be using LED backlights for all of its notebooks and new 24-inch Apple Cinema Display, and one year later it introduced a new LED iMac, meaning all of Apple"s new computer screens are now LED. Almost every laptop with a 16:9 display introduced since September 2009 uses LED-backlit panels. This is also the case for most LCD television sets, which are marketed in some countries under the misleading name LED TV, although the image is still generated by an LCD panel.

Most LED backlights for LCDs are edge-lit, i.e. several LEDs are placed at the edges of a lightguide (Light guide plate, LGP), which distributes the light behind the LC panel. Advantages of this technique are the very thin flat-panel construction and low cost. A more expensive version is called full-array or direct LED and consists of many LEDs placed behind the LC panel (an array of LEDs), such that large panels can be evenly illuminated. This arrangement allows for local dimming to obtain darker black pixels depending on the image displayed.

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

If the frequency of the pulse-width modulation is too low or the user is very sensitive to flicker, this may cause discomfort and eye-strain, similar to the flicker of CRT displays.

For a non-ELP backlight to produce even lighting, which is critical for displays, the light is first passed through a lightguide (Light guide plate, LGP) - a specially designed layer of plastic that diffuses the light through a series of unevenly spaced bumps. The density of bumps increases further away from the light source according to a diffusion equation. The diffused light then travels to either side of the diffuser; the front faces the actual LCD panel, the back has a reflector to guide otherwise wasted light back toward the LCD panel. The reflector is sometimes made of aluminum foil or a simple white-pigmented surface.

The LCD backlight systems are made highly efficient by applying optical films such as prismatic structure to gain the light into the desired viewer directions and reflective polarizing films that recycle the polarized light that was formerly absorbed by the first polarizer of the LCD (invented by Philips researchers Adrianus de Vaan and Paulus Schaareman),

The evolution of energy standards and the increasing public expectations regarding power consumption have 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.

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

While not an LED display, a television using such a combination of an LED backlight with an LCD panel is advertised as an LED TV by some manufacturers and suppliers.

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.

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.

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), 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.

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.

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,

A first dynamic "local dimming" LED backlight was public demonstrated by BrightSide Technologies in 2003,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.

LED-backlit LCDs have longer life and better energy efficiency than plasma and CCFL LCD TVs.mercury, an environmental pollutant, in their manufacture. 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.

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.

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 dors may be in a separate layer as a quantum dot enhacement 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.Consumer Electronics Show 2015.quantum dot displays at CES 2017 and later formed the "QLED Alliance" with Hisense and TCL to market the technology.

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.

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.

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is the backlight part of the lcd screen brands

Choosing a backlight system for LCD screen displays is a major consideration. It will determine a lot about your experience of the display and requirements during production. Different backlight options provide widely different effects in the contrast and brightness of the display. Also, depending on which backlight option you choose, it will affect some or all of the following: the cost of the overall product; how many products you will have to order due to manufacturing constraints; and how environmentally friendly the component parts are that make up the product.

The word LCD has been used to describe many display technologies. Often people believe that LCD screen displays are the same as a CRT (Cathode Ray Tube), an LED Display (Light Emitting Diode) or a Plasma display. This is not the case! Let’s discuss what an LCD is and what it is not.

Think of the liquid crystal display (LCD) as a window blind. Positioned in one direction the blinds allow light to pass through, or turned another direction they block the light. Just like a window blind, the LCD does not create its own light, it only blocks or allows it to pass through.

As you know, you can adjust the blinds to alter the amount of light desired. When fully closed, the blinds block light completely; when open, all light passes through; and when angled, partial light comes in. An LCD works similarly to this, with one significant enhancement: an LCD has the ability to block light in some areas and allow light to pass in other locations of the glass. An example of this is the display used on a gas pump. The customer sees numbers where the light is blocked, and a clear area where the light is allowed to pass through.

LCD’s are not CRT’s, LED’s, nor are they Plasma displays. Each of these types of displays produces their own light and are called emissive displays. Emissive displays require more power than an LCD.

Emissive displays have a distinct advantage in that they can be seen clearly at night whereas LCD’s cannot. However, the solution to this problem of low-light visibility is to install a backlight behind the LCD. Backlights do require more power than the LCD itself, but they can be turned on only when necessary. Many products that are powered by batteries will have the backlight dim or shut off after a certain amount of time. This can be seen on cell phones and watches. Consequently, even though a little more power is used for the backlight than used in a stand-alone LCD, because it is not constantly on, the LCD’s with backlights wind up using less power than their emissive display competitors. LCD screen displays using backlights become the clear choice.

This option is the most popular for products that have a lower power budget. Products that run on battery need to conserve power and the lowest powered backlight available is to have no backlight at all.

The Amazon Kindle is a perfect example. The Kindle makes use of a display technology called ‘e-paper’, which looks more like a printed page than any other device on the market currently. This specific e-book reader does not contain a backlight. Because it omits the backlight it can operate up to one month without recharging. Imagine, you could take it on a cruise to Fiji and back and never have to worry about recharging it!

Thinking back to your product, not all products can omit a backlight; in fact it may require one. If it does need a backlight the most popular option is an LED.

A light emitting Diode (LED) is a semiconductor that produces light when current is passed through the device. Light is created from the energy conversion that takes place in the LED die. The advantages of an LED are:LED lights are much more rugged and can handle shock much better than other types of lights.

LED backlights are made up of an array of LED’s. They come in a variety of colors including red, green, yellow, amber, blue, white and R/G/B (Red/Green/Blue). From the R/G/B trio any color in the rainbow can be made.

The majority of the LED backlight colors will operate with a half-life of 50K to 70K hours. (Remember, half-life is when the light will be half as bright as when it was first turned on. This is not when the LED will burn out.) Blue and white LED’s do have a shorter half-life than other colors. Presently, they are rated at 30K hours. That means that if you turned them on today and left them on, in 3.4 years they would be half as bright as they are today! One thing to take into account is that as technology improves, the lifetime of the LED’s will become longer, which will also increase the half-life. Below is a photo of a blue LED backlight.

To make LED’s display correctly, they are placed behind the LCD screen display in an array pattern. The challenge is that LED’s, similar to a light bulb, project a beam of light which can show spots of light. These spots are called hot spots. This can be an issue with LED’s since they will make the display look like it has polka dots. Below is a photo of a LED behind the LCD glass. This problem will be solved with the use of a diffuser.

A diffuser is like a lamp shade and is placed between the glass and the LED’s. The goal is to disperse the light or make it more even. Below is a photo of a diffuser. At the bottom of the diffuser you will see the LED’s. This is where you can see hot spots. But as the light travels further into the diffuser, the light becomes more even. The diffuser solves the issue with hot spots and makes LED’s a very attractive option.

EL (Electro Luminescent) backlights, also known as ELP’s (Electroluminescence Panel), have been used as a backlight for LCD’s for several years. They are available in a range of colors with white being the most popular. EL technology makes use of colored phosphors to generate light. They require AC (alternating current) rating of 100VAC @ 400Hz.

In the last three to four years, EL backlights have decreased in popularity. There are several reasons for this drop in popularity.The EL backlight requires an inverter to convert DC to AC. The cost of the inverter increases the cost of the overall LCD Display.

The half-life of an EL is an estimated 3,000 to 5,000 hours. (Once again, half-life is when the backlight is half as bright as when it was first turned on.)

LCD screen display manufacturers now require an MOQ (Minimum Order Quantity) of no less than 500 displays for orders that include EL backlights. This MOQ number is likely to increase in the future as this type of backlight becomes less popular. Additionally, as the demand drops the price will naturally increase.

A Cold Cathode Fluorescent Lamp (CCFL) is similar to the long fluorescent light bulbs you see in the ceilings of offices. Below are photos of various types.

This technology has been in use for many years, but in the last few years the popularity of this type of backlight has decreased. There are a few reasons why this is so.Similar to EL backlights, this technology operates on AC.

The majority of LCD screen display manufacturers no longer offer CCFL as an option. There are too many negatives and not enough positives to their use. The suppliers that do offer this now require a very high MOQ (Minimum Order Quantity).

When choosing the type of backlight for your LCD screen displays it is important to keep in mind MOQ’s and future availability. Make sure you are choosing a technology with a future so that your product has one too!

is the backlight part of the lcd screen brands

The world of LCD backlights can be a confusing one. Determining the right option for your LCD screen can be a challenge as a result. The solution you choose depends on the application, frequency of use, and perhaps your budget. However, different types of backlighting produce different results.

Whether you’re looking to replace your LCD lighting with LED or CCFL lights or just want to know which option is best for you, this brief guide will help you better understand what LCD backlighting is and what options are available.

First, let’s explore what LCD backlighting is. If you’ve made it this far, chances are you already have a general idea, but for those of you who don’t, LCD stands for Liquid Crystal Displays. Because pixels in LCDs are similar to shutters, their contrast relies on the underlying electrical current. To properly illuminate an LCD, a light source must be placed behind the color pixel panel.

It’s important to note that not all LCDs use a backlight. Backlighting simply allows the viewer to see the display more clearly in low light conditions. For commercial purposes, this is important since the consumer must be able to use the screen properly regardless of the external lighting conditions.

LCD displays often run 24/7, which means they lose their brightness over time, often in 3 years or fewer. That’s why replacements are often necessary. There are two primary types of LCD backlighting replacements—CCFL and LED.

CCFL stands for Cold Cathode Fluorescent Lamps. These backlights work very much like the traditional fluorescent lamp and come in a single straight or shaped glass tube. Inside the tube is low-pressure mercury vapor. Once ionized, it emits ultraviolet light. Since humans cannot detect UV light, a coat of phosphorus inside the tube translates it into a white bright light that we can see.

LED stands for Light-Emitting Diode. LED backlights work much differently than CCFLs in that they require 10 to 18 white individual LEDs. They are laid in a uniform pattern. To make things even more complex, white LEDs are actually blue LEDs with a yellow phosphor coating that causes us to see a white light.

To control where and how light is displayed on your chosen screen, a display panel consisting of two sheets of polarizing material with a liquid crystal solution placed in between is utilized. Again, this is where an electric current comes into play. That current will pass through the liquid. The result is a pattern based on how the crystals align, depending on if the light should or shouldn’t pass through it. Crystals serve as a barrier to create the resulting light display.

Keep in mind that both CFFL and Led can be custom tuned to produce nearly any color and color temperature of light. However, they each have different advantages and disadvantages.

CCFLs are the traditional standard for backlighting. They are the tried-and-true option for backlighting any LCD display. Why? There are several reasons.

On the other hand, LED backlights are getting more traction as of late. They are relatively new and most experts consider them the backlighting preference of the future. Most new displays are only available with LED replacements. However, LEDs do come with one major downside—they cost more than CCFLs, sometimes twice as much. Keep in mind, it is typically best to stick with using the type of backlight that your OEM screen was designed to use, regardless if it is LED or CCFL. One exception is if you have customized your display for LED use.

Yet, some of the advantages of choosing an LED include superior brightness levels, no inverter is required (only a power supply), durability is better, and they can provide longer life (for more cost).

Depending on your application, other types of backlighting might also be available. LCD TVs, for example, use both full-array and direct local backlighting. Direct local dimming is similar to full-array, but there are fewer LEDs spread across a wider area than you’d see with full-array backlighting. For manufacturers, however, there is a difference. LEDs that are spaced farther apart do not have the same consistency or accuracy in lighting that full-array displays do.

If your LCD screen is dimming and not offering the same consistent bright display as it once did, it could be time for repairs. A common repair is CCFL or LED replacement. In fact, companies like Plazmo make exact OEM replacements for the original backlight in the LCD, regardless if it is LED or CCFL.

LCD repair or removing and replacing LCD backlighting is simple but does require some steps. It is far more cost effective than total replacement as well. Your LCD is unique, which means you need to carefully analyze the manufacturer’s information before you go about removing the previous CCFL backlight. You’ll likely need to remove any outer casing you encounter and possibly the screen itself, depending on the application.

You will also have to work around a copper ground or LCD controller board because these often limit access to the backlight. Noting where you removed these items and where they should go back to is important during the removal process.

Next, access the CCFL bulb. Often it has its very own spot. Remove the rubber caps from the previous bulb and add them to your replacement bulb. Run the power cable back into one end of the new bulb—potentially using a soldering tool to do so. If you don’t want to do the rebuilding of your CCFL assembly, check out our mail in repair services here.

After you finish these steps, replace the CCFL and any other components back into your display and test the result. In the vast majority of cases, your screen will be returned to its full brightness potential, just like new.

Did replacing your bulb not do any good? Then you might be dealing with dying capacitors, inverters, or transistors. You’ll need electrical equipment like a voltmeter, to take a measurement of the electrical current flowing into important components.

Whether you aren’t quite sure which backlight your LCD repair needs, or you have not been able to find the CCFL or LED for your screen anywhere, it might be time to contact a professional. Finding the correct backlight can be challenging and getting it wrong can cause you a serious headache.

The good news is, if you opt to choose Plazmo for your replacement parts or LCD repairs, you’re in good hands. We offer affordable replacements that get your screen back to its original brightness without the high costs of buying an entirely new panel.

Give our site a browse to find the right components for your LCD display or contact us at sales@plazmo.com if you’d like to have us do the heavy lifting for your repairs.

is the backlight part of the lcd screen brands

Traditional LCDs use CCFLs, or cold-cathode florescent lamps, as their backlight. While cheap, they"re not as energy efficient as LEDs. More importantly, all contain mercury, and aren"t able to do some of the fancy area-lighting of which some LED backlit models are capable. Because of these issues and the falling prices of LEDs, CCFL backlit LCD TVs will disappear entirely very soon. In 2013

Most LED LCDs on the market today are edge-lit, which means the LEDs are in the sides of the TV, facing in toward the screen. In the image at the top, the LED strips are above and to the side of this exploded-view of an LCD panel. There"s a close-up view here (full article with more images

There are a few models that are have their LEDs arrayed on the back of the TV, facing you. These are less common, though are making a comeback in the form of cheaper, but thicker, mostly low-end LED LCDs. There are a handful of high-end TVs that use full-array LED backlighting in a slightly different way, which we"ll discuss later.

Because the light is brightest nearest the LEDs, it"s common for edge-lit LED LCDs to have poor uniformity. This is especially noticeable on dark scenes, where areas of the screen will appear brighter than others. Corners or edges can have what looks like tiny flashlights shining on the screen. Check out

Each manufacturer has a preferred method for edge-lighting, but some models may feature one type, while other models feature another type. Generally speaking, the fewer LEDs the cheaper the TV is to produce. Fewer LEDs also mean better energy efficiency, but LED LCDs are already so efficient that this is a tiny improvement. Unfortunately, specific details about where a TV"s LEDs are located (beyond "direct" or "edge"), the number of LEDs, and other useful information about the backlighting, are rarely listed on a TV"s spec sheet.

The biggest difference between all the LED back/edge-lighting methods is how effective their "local dimming" is, which as you"ll see, has become a pretty broad term.

This design has all the LEDs along the bottom of the TV. Though manufacturers don"t like to reveal how many LEDs they use, this is likely the type with the least number of LEDs.

Though TVs of this style claim to have "local dimming" you can see how this is a pretty broad definition of "local." Even if each LED is dimmable independently (highly unlikely), you"re still only able to dim columns that stretch from top to bottom. Something like this:

As you can guess, this design has LEDs on the top and bottom edges of the screen. The local dimming here is a little better, where the zones can be slightly smaller areas of the screen, like this:

This is a less common method now, as it requires more LEDs than any of the other edge-lighting methods. The local dimming can get a little more accurate, but is still limited to large-ish zones. If we used our moon example image, the result with an all-sides edge-lit would look just like top and bottom. But with regular video (that has more light sources than just the moon), it will have a more zones to work with, sort of like this:

All Sides used to be the most common edge-lighting method. But as the light guides improved, and costs had to come down (to make cheaper LED LCDs), this method became fairly rare.

Nearly all "backlit" LED LCDs use this method. The LEDs are arrayed on the back of the TV, facing you, but there is no processing to dim them individually. They work instead as a uniform backlight, like most CCFL LCDs. The least expensive LED LCDs use this method, as do most of Sharp"s

This is the ultimate LED LCD, offering performance that rivals the better plasmas. Like the "direct-lit" TVs, these have their LEDs behind the screen (the image above for direct-lit works as a visual aid for this type as well). The full local-dimming aspect means the TV is able to dim zones behind the dark areas of the screen in fairly specific areas to make the image really pop, drastically increasing the apparent contrast ratio.

However, they basically don"t exist. The LG LM9600 wasn"t great last year, and LG has yet to announce any full-array local-dimming TVs for 2013. The only other local-dimming LED LCD was the Sony HX950, which was excellent, and is still current. In his review David Katzmaier called

The two biggest-selling TV makers in the U.S. are Samsung and Vizio, and neither has sold a full-array local-dimming LED TV for the last couple years. At CES 2013, Samsung"s only such TV announced was the insanely-expensive E420i-A1, saying "Sure, black levels get darker, but the trade-off in shadow detail is one I"m not willing to make," and concluded that its "local dimming does nothing to improve picture quality."

As I mentioned at the top, there"s no easy way to tell, just by looking at a spec sheet, what kind of backlight a TV has. By extension, there"s no way to tell how good its local dimming will be. Bad local dimming can, at worst, just be marketing hyperbole. At best, it does little to improve the picture. Good local dimming, however, can make a punchy image, with lots of apparent depth and realism. Or to put it differently, the best LCDs on the market have the best local dimming, allowing them to rival plasmas on the picture quality front. The better TV reviews, like ahem those here on CNET, will talk about all this, so you"re not duped into paying for a "feature" that"s little more than a check mark on a spec sheet.

Got a question for Geoff? First, check out all the other articles he"s written on topics like Send him an e-mail! He won"t tell you what TV to buy, but he might use your letter in a future article. You can also send him a message on Twitter: @TechWriterGeoff.

is the backlight part of the lcd screen brands

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is the backlight part of the lcd screen brands

Plasma screens contain tiny pockets of gas that get excited when voltage is applied to them, turning them into a state of plasma. In that state, the voltage then strikes electrons of mercury, turning them into ultraviolet (UV) light, which isn"t visible to the human eye. The UV light then passes through phosphor cells; each pixel contains red, green, and blue phosphor cells. Thanks to these phosphor cells, the TV can turn the UV light into colors that are visible on the light spectrum. Essentially, plasma TVs don"t require a light, and each pixel is self-emissive, so how one pixel displays itself is independent of the next pixel.

Since each pixel emits its own light, blacks are really deep. When the television wants to display black, it simply emits no light at all for the selected pixels. However, these aren"t perfect blacks because each pixel retains a bit of voltage, leaving a bit of light to pass through. Each pixel emits light in all directions, creating wide viewing angles, so the image remains accurate when viewing from the side.

The pixels aren"t excited continuously, but in short pulses, and some plasma TVs can pulse up to 600 times every second. The naked eye perceives this as flickering, and some people are very sensitive to this. There can also be some advantages to this; since each pixel holds a certain charge, it"s ready to turn on and off as needed, resulting in minimal motion blur. This means that fast-moving content, like in sports or video games, appears smooth.

One of the downsides of plasmas was how they suffered from occasional image retention if they displayed the same image for a long period. So if you watched the news for about an hour, with all of its static displays, then switch channels, you"d still see the outline of the static elements. Eventually, they disappeared, but it could have been particularly annoying. Also, after several years in use, plasmas suffered from permanent burn-in. This happened when the phosphor cells simply stayed stuck in one color and couldn"t display any colors. 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. Since 2012, they"ve replaced plasma as a competitor to LCD TVs, and to learn more about OLEDs and how they differ from LCD TVs, see here.

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.

By using a backlight, LCD TVs use much less power than plasmas, which you can read about here. Also, LCD TVs tend to get much brighter than plasmas, making them more suitable for well-lit rooms. There are two main types of backlights used in LCD screens: CCFL and LEDs.

When someone refers to an LCD TV, they usually mean a Cold-Cathode Fluorescent Lamp (CCFL) backlit LCD screen. The first LCD TVs were lit by CCFLs, but they"re extremely rare as of the start of the 2020s. 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.

CCFL-backlit LCD TVs were eventually replaced by LED TVs because they cost less, were made thinner, and required less power. Also, LED TVs have more control over their backlight, resulting in vivid colors and better picture quality.

An LED (Light-Emitting Diode) screen is an LCD screen, but instead of having a normal CCFL backlight, it uses LEDs as the source of light behind the screen. Companies label their TVs as LED, even though they"re technically LCD; it can be confusing at times, but if you see an LED TV, you know it has an LCD panel. These TVs are more energy-efficient and a lot smaller than CCFLs, enabling a thinner television screen.

In a full-array LED screen, the LEDs are distributed evenly behind the entire screen. 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.

With an edge-lit LED screen, the LEDs are placed at the edges of the screen. 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.

As TV companies attempt to improve their technology, a new type of LED backlighting has emerged: Mini LED. It uses the same traditional LED backlighting behind an LCD panel, except the LED lights are even smaller. 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 2021, but it now seems that manufacturers are starting to use the technology more often. The Samsung QN90A QLED is an example of a Mini LED TV.

Another technology, Micro LED, is only in its initial phases of development. This doesn"t even have an LCD panel as each LED pixel is self-emissive, similar to OLEDs, but without the burn-in risk. Currently, there aren"t any Micro LED TVs available at the consumer level; Samsung has produced large Micro LED TVs (over 100 inches), and they"re very expensive. However, we may begin to see Micro LED technology in the consumer TV market soon.

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 mid-2000s. Plasma TVs are now extinct, and although OLEDs share many of the same characteristics, LED-backlight LCD TVs are now the norm, and it"s likely your next TV purchase will have an LCD panel.

is the backlight part of the lcd screen brands

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.

is the backlight part of the lcd screen brands

The headphone jack sounds like a classic mechanical problem -- the iPod series will pause playback if they think you have unplugged the headphones. Pocket lint often finds its way into the jack, and you can fix it temporarily by blowing air into the jack, but it will eventually fail. You might open the whole thing up to fix the LCD and see if you can clean it better from inside -- there are no specific guides for it, probably because it seems to be soldered in :/

The backlight is part of the LCD assembly -- it"s possible that the problem is with the logic board, but it sounds pretty likely that replacing the LCD will fix your problem.

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is the backlight part of the lcd screen brands

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is the backlight part of the lcd screen brands

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is the backlight part of the lcd screen brands

Armed with a warehouse filled with LCD displays, cameras, ultrasound systems, film digitizers, graphics cards, and imaging accessories, the necessary tools to complete your medical suite are easily acquired through Ampronix.

LED Backlight flat panel LCD monitors present physicians with clear imagery, accurate depth perception, and lag free transmission. Featuring full HD or 4K Resolution, these displays cover a wide color gamut to produce the most intricate of details of the human viscera during a procedure. With presented images of unrivaled color Ampronix distributes LED Backlight displays from world renowned companies like Barco, Sony, and NEC to ensure healthcare efficacy and ensure physician and surgeon satisfaction in the procedure. These monitors can be used in a variety of healthcare environments including OR"s, radiology labs, presentations, in endoscopy exams, and in conference room settings.

Ampronix supplies the best in new and refurbished LED Backlight Displays and accessories such as power supplies, transmitters, controller cards and cable extensions. Almost all LED Backlight Displays come with an Ampronix warranty for one year after purchase.

As a leader in medical imaging technology since 1982, Ampronix develops, distributes, and services groundbreaking solutions that promote optimal patient outcome. Our goal is to offer the assurance necessary to overcome operational and financial obstacles of the evolving healthcare industry.

The world class Research and Development team at Ampronix specializes in developing innovative medical imaging solutions to overcome challenges created by gaps in current technology. Our expert engineers design products as a solution for OEM (Original Equipment Manufacturer) companies that always exceed their expectations.

After 40+ years of building relationships with industry leaders, Ampronix has become an established master distributor for many reputable brands. Maintaining these prosperous partnerships is how Ampronix is able to offer high caliber products with preferred pricing. Moreover, we equip international distributors with a variety of our innovative products in order to support their growth.

With over a century of combined experience, Ampronix’s state of the art service facility employs highly qualified technicians to diagnose and repair all types of imaging equipment and peripherals. In fact, our experts expose and correct manufacturer weaknesses, which result in longer lasting, more efficient equipment.

Since our humble beginnings, we have focused on putting the satisfaction of clients first, as professionalism is our cornerstone. With reliability, safety, and quality at the core of our philosophy, Ampronix is dedicated to helping others save lives and create a healthier tomorrow for future generations.

is the backlight part of the lcd screen brands

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