is the backlight part of the lcd screen free sample

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.

Illuminating Arrangement for a Field-Effect Liquid-Crystal Display as well as Fabrication and Application of the Illuminating Arrangement, filed Oct. 15, 1976.

"First-Hand Histories: Liquid Crystal Display Evolution - Swiss Contributions". Engineering and Technology History Wiki. Archived from the original on July 3, 2017. Retrieved June 30, 2017.

Competing display technologies for the best image performance; A.J.S.M. de Vaan; Journal of the society of information displays, Volume 15, Issue 9 September 2007 Pages 657–666; http://onlinelibrary.wiley.com/doi/10.1889/1.2785199/abstract?

LED TVs: 10 things you need to know; David Carnoy, David Katzmaier; CNET.com/news; 3 June 2010; "LED TVs: 10 things you need to know". Archived from the original on 2017-12-01. Retrieved 2017-11-22.

Method of and device for generating an image having a desired brightness; D.A. Stanton; M.V.C. Stroomer; A.J.S.M. de Vaan; US patent USRE42428E; 7 June 2011; https://worldwide.espacenet.com/publicationDetails/biblio?CC=US&NR=RE42428E

LED local dimming explained; G. Morrison; CNET.com/news; 26 march 2016; "LED local dimming explained". Archived from the original on 2017-11-23. Retrieved 2017-11-20.

Pixel-by-pixel local dimming for high dynamic range liquid crystal displays; H. Chen; R. Zhu; M.C. Li; S.L. Lee and S.T. Wu; Vol. 25, No. 3; 6 Feb 2017; Optics Express 1973; https://www.osapublishing.org/oe/viewmedia.cfm?uri=oe-25-3-1973&seq=0

Dimming options for LCD brightness; J. Moronski; Electronicproducts.com; 3 Januari 2004; "Dimming options for LCD brightness control". March 2004. Archived from the original on 2017-07-28. Retrieved 2017-11-20.

Brochure 3M Display Materials & Systems Division Solutions for Large Displays: The right look matters; "Archived copy" (PDF). Archived (PDF) from the original on 2017-08-02. Retrieved 2017-11-20.link)

Broadband reflective polarizers based on form birefringence for ultra-thin liquid crystal displays; S.U. Pan; L. Tan and H.S. Kwok; Vol. 25, No. 15; 24 Jul 2017; Optics Express 17499; https://www.osapublishing.org/oe/viewmedia.cfm?uri=oe-25-15-17499&seq=0

Polarisation-sensitive beam splitter; D.J. Broer; A.J.S.M. de Vaan; J. Brambring; European patent EP0428213B1; 27 July 1994; https://worldwide.espacenet.com/publicationDetails/biblio?CC=EP&NR=0428213B1&KC=B1&FT=D#

Energy Efficiency Success Story: TV Energy Consumption Shrinks as Screen Size and Performance Grow, Finds New CTA Study; Consumer Technology Association; press release 12 July 2017;

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Controlling Power Consumption for Displays With Backlight Dimming; Claire Mantel et al; Journal of Display Technology; Volume: 9, Issue: 12, Dec. 2013; Mantel, Claire; Burini, Nino; Nadernejad, Ehsan; Korhonen, Jari; Forchhammer, Soren; Pedersen, Jesper Meldgaard (2013). "Controlling Power Consumption for Displays with Backlight Dimming". Journal of Display Technology. 9 (12): 933–941. Bibcode:2013JDisT...9..933M. doi:10.1109/JDT.2013.2260131. S2CID 24082090.

LED LCD backlights are small light strips, or light sources, contained inside a display, TV, or monitor to provide lighting for the screen. All LED TVs are LCD panels with LED backlighting. A common misconception is that LED displays are different from LCD when fundamentally they are the same. LED is better described as a sub-set of LCD devices.

LCD is an acronym for Liquid Crystal Display, which is a type of monitor or screen—and flat-panel technology—that relies on thousands or millions of pixels, arranged in a rectangular grid. When an LCD is turned on, each pixel takes on a red, green, or blue sub-pixel (RGB) that is either enabled or disabled. When the pixels are off, the individual section appears black, and when all of the sub-pixels are on, it appears white. Collectively, the arranged pixels provide the sharp image on the display by being in either an on or off configuration.

The LED backlight illuminates the pixels, from behind, making them appear richer and brighter. Not all LCDs have a backlight, and for those that do, not all of them utilize LED backlighting. Some displays also use CCFL lighting or Cold-Cathode Fluorescent Lamps. Although, it should be noted that CCFL displays are being phased out in favor of LED-backlit panels.

The liquid crystals inside an LCD panel don’t have any illumination on their own and require the light to come from a separate component, which, in this case, is provided by the LED backlighting.

Older display types, such as cathode ray tubes (CRT) produce illumination already and so they do not need an additional light source like LCD devices.

While it can be confusing at first, LED-backlit panels are different from a full LED. LED-backlit panels have LED strips lining the edges of the screen whereas full HD illuminates the entirety of the display often with higher brightness and color accuracy. Full LED panels achieve this thanks to an evenly distributed light source across the rear of the set.

This changes the picture on the display, particularly when it comes to dark scenes and true black colors. On an LED-backlit display, for example, dark scenes may appear washed out because of how the light is focused on the edges and spreads thinly into the center.

Full LEDs, on the other hand, can achieve true blacks, with even brightness levels because the light spreads across the entire panel accurately. That also means the lights in the full-LED panel can be disabled or turned off individually to create a darker image.

Because both types are fundamentally LCD panels, both LED and LED-backlit displays produce bright and vivid pictures. However, scenes may appear brighter or slightly washed out, depending on how the light source is distributed, such as from edge backlighting versus evenly distributed lighting. If you prefer a more accurate picture, full LED panels are the way to go, but they are more expensive.

Similar to TVs and other displays, an LED-backlit LCD monitor is an LCD panel with LED backlights. What often sets a monitor or computer monitor apart from standard displays is they don’t include a built-in tuner, which is needed to access cable. They often include different video or display ports, such as HDMI, DisplayPort, VGA, and so on. They"re designed to be used as a primary or secondary display for desktop computers, laptops, and beyond.

Monitors are generally full LED panels with a fully distributed light source. This allows them to provide a brighter and sharper image overall, which is ideal for computer-related activities and media.

LED-backlit TVs, monitors, and displays are used in many different places including ATMs, cash registers, digital billboards, fitness equipment like treadmills, vehicle infotainment systems, gas station pumps, Pachinko, and casino machines, mobile devices, and much more.

To clean a flat-screen TV, turn off the device and use a dry microfiber cloth to gently wipe the screen. If necessary, dampen the cloth with distilled water or an equal ratio of distilled water to white vinegar.

If you want to replace your TV or computer screen, you should check with the manufacturer to see if they offer repair services. If not, try Best Buy or another electronics repair shop.

While all LED TVs are LCD TVs, not all LCD TVs are LED TVs. If a TV is marketed as LCD with no mention of LED, then it probably uses a different type of backlighting such as CCFL.

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.

LCD displays don’t emit light by themselves. They need a light source, and LED backlights are now dominating the market. In this article, Orient Display’s Bill Cheung provides a complete overview of LED backlight technology, discussing different types, driver technologies, color deviation, brightness options and more.

LCD (liquid crystal display) has long been the dominant technology in the display world. Certainly, there are some emerging competing display technologies—such as OLED (Organic Light Emitting Diode) [1] and micro-LED—that have the potential to threaten LCD’s position in the market. But both are currently only used for niche and high-end markets.

An LCD display can’t emit light by itself. In order to have an LCD display [2] used in a dim environment, a backlight has to be used as the light source. There are a few different technologies that are able to produce backlight ranging from EL (electroluminescent), CCFL (cold cathode fluorescent lamps) and LED (light emitting diode). However, a breakthrough in blue LED technology by Shuji Nakamura [3] led to LED backlights dominating the market.

One of the greatest benefits of LED backlighting is its long lifetime. Normally, LED lifetime can be measured with half-life when the original brightness decreases by 50%. With different LED chip manufacturing materials, technologies and environment used, the LED life can vary from 20,000 hours to well over 100,000 hours.

LED backlights have low power consumption and produce much less heat than other backlight technologies, which extends the durability and performance of the other display components. Furthermore, this reduces the risk of fire and explosion. LED backlights are also driven with DC (direct current) and low voltage (can be as low as 1.5V), which are good for battery drive and emit no interference to the circuitry. With the development of LED technology, the LED chips become small. So, it is possible to produce very thin backlight (0.5mm thick or thinner).

Although white LED is the most popular color, LED backlight can be made into different single colors, bi-colors and tri-colors [4] (Figure 1) (Figure 2). With RGB LED backlight color mixing, normal 8 color LED backlight can be produced (Figure 3).

LED backlight can be classified as bottom (array) lit and side (edge) lit backlights, and each have their plusses and minuses. The advantages of the bottom lit (array) backlight are that it is uniform and bright. Its disadvantage is high current draw, thickness, heat dissipation and cost. Meanwhile, the advantages of the side lit backlight are its thinness, flexibility in design, low current and lower cost. The main disadvantage of the side lit backlight is its non-uniformity—hot spots can be seen from most of the side lit backlight from certain angle. Figure 4 compares the bottom lit and side (edge) lit backlight LCD types.

Now let’s look at LED backlight structures. An LED backlight can be simplified into layers starting with a LED chip, light guide, diffusor and reflector (Figure 5). This is the lowest cost structure. Except for some very low current efficiency LCD displays—such as utility meters, battery-powered clock, watch, GPS and so on—most LCD displays need backlights to be visible in the dim lighting. Most often the backlight is actually at the back of the LCD. In rare cases, this light can be done as front light. The traditional LCD structure with LED backlight shown in Figure 6.

Direct current driving: This is the simple and low-cost way to drive a LED backlight, however, be mindful of the current limit otherwise the LED life can deteriorate quickly. The solution is simply to add a current limiting resistor in the circuit. Current limitation resistors value calculation formula: R = (V0– Vf)/If.Also be mindful of reverse drive, otherwise, the LED chip can break down easily.

LED driver with constant current: The advantage of constant current LED driver is that it will be the best option to use when building your own fixture or working with high powered LED because they avoid violating the maximum current specified for the LEDs, therefore avoiding burnout/thermal runaway. They are easier for designers to control applications, and help create a more consistent bright light.

LED driver with constant voltage: Using a constant voltage LED driver makes sense when using an LED or array that has been specified to take a certain voltage. This is helpful because constant voltage is a much more familiar technology for design and installation engineers. Moreover, the cost of these systems can be lower, especially in larger scale applications.

There are a variety of ways to connect a backlight and LCD module electrically. It can be done with wires that are soldered on the LCD or LCD module. It can be connected using pins, which can be soldered onto the LCD or LCD module. A third way is to use a FPC (flexible printed circuit), which can be soldered or plugged in a ZIF (zero insertion force) connector. And finally, there is the connector method. With this method you use connectors which can be plugged into mating connectors.

As the LED is manufactured via the semiconductor process, there are some color deviations that can be a quality control issue. One way to solve the issue is through a process of selection and sorting after manufacturing the LEDs. The LEDs are sorted into different categories or bins. How this sorting is done and what each bin actually contains is defined differently by each LED manufacturer. The backlight manufacturer can choose from which bin they take the LEDs for backlight color hue.

Some customers might request very fine binning by the LED manufacturer, which can be very expensive since only a very small percentage of the LEDs manufactured would meet the requirements for a specific bin. Figure 7 shows an example of the bin selection from Nichia, the most renowned LED manufacturer in the world. Figure 8 shows the 1931 CIE chromaticity diagram. And Figure 9 shows the color deviations (bin definition) by Cree for a qualified production lot.

In actual LED backlight production, most customers will accept the LED color for two big categories: white with yellowish (warm) and white with bluish (cold). Of course, the LED brightness will also need to be defined. For general application, most customers will accept a brightness tolerance of 70 percent.

It is extremely hard to estimate the LED backlight lifetime or MTBF (mean time between failures) because there are so many variable factors. However, the most important is the temperature on the LED chip. The factors that can affect the LED chip temperature include: surrounding temperature, humidity, driving current, voltage, backlight design (how many LED chips to be used, how close to each other, heatsink design), backlight manufacturing process (type and thickness of adhesive), quality of the LED chip and so forth.

To test the LED life is also very time consuming, requiring at least 1,000 hours. That’s the reason why no LED manufacturers can guarantee LED backlight life and most backlight manufacturers also are reluctant to provide lifespan data. As for LCD manufacturers, they need to discuss it with the customer to understand the applications and provide suggestions. It is normal that the LCD datasheet lists the typical life time and avoids providing a minimum lifetime. From Figure 10, we can see that over room temperature, the current needs to decrease as the temperature increases. At over 85°C, the LED is not usable.

To estimate LED backlight lifetime, you can use ballpark estimation or theoretical calculation. Let’s first examine the ballpark method. To take white LED as example, the nominal biasing current is 20mA. If we use a safe lifetime estimation, we can estimate using Table 1.

Now let’s use the theoretical calculation approach. As we previously mentioned, LED life is affected by a lot of factors: surrounding temperature, humidity, driving current, voltage, backlight design (how many LED chips to be used, how close to each other, heatsink designed), backlight manufacturing process (type and thickness of adhesive), quality of the LED chip and so on. LED chip manufacturers are not willing to give absolute values of LED chip lifetimes, but there is a theoretical calculation that we can use.

Temperature is the determination factor for LED chip life, while LED chip manufacturers use LED junction temperature to predict LED chip life more accurately. An example is:

Where Tjis PN junction temperature (°C); Ts1 is solder temperature cathode side (°C); Rthj-s1 is thermal resistance of junction to Ts1 measuring point (°C/W); W is IF × VF; and, for Nichia NS6W083A Tj Max = 120°C, Rthj-s1= 10°C/W.

Finally, let’s look at ways to increase LED backlight brightness. There are many ways to increase LED backlight brightness, but all these measures are balanced with performance and cost. Here are some of the methods:

For the LCD module side, using better aperture opening ratio, anti-reflection coating on surface, optical bonding. This results in higher cost. Actually, this measure is not to increase LED backlight brightness directly but to increase to the visibility to users.

Using 3M film [6]: BEF (brightness enhancement film or prism film), DBEF (dual brightness enhancement film), DBEF II, ESR (enhanced specular reflector) and so on. These increase costs a lot, but these high-performance films are essential in tight power management like mobile phones and other battery-powered applications.

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Bill Cheung is an engineering lead and marketing manager at Orient Display, an LCD and display technology provider with over two decades of industry experience in delivering cutting edge display solutions. You can browse Orient Display"s knowledge base [7] to learn more about LCDs.

Affected devices were sold between October 2016 and February 2018. Apple or an Apple Authorized Service Provider will service affected MacBook Pro units, free of charge.

To identify your computer"s model and to see if it is eligible for this program, choose Apple () menu > About This Mac. Eligible models are listed below.

Please choose one of the options below for service. Your MacBook Pro will be examined prior to any service to verify that it is eligible for this program.

Note: If your MacBook Pro has any damage which impairs the service, that issue will need to be repaired first. In some cases, there may be a cost associated with the repair.

The program covers eligible MacBook Pro models for 5 years after the first retail sale of the unit or 3 years from the start date of this program, whichever is longer.

This graphic LCD module acts as a shield for Arduino Uno-style microcontrollers. The pins on the carrier board match up to the Arduino Uno"s ports, so the module simply presses on and is fully and correctly connected. Plus, this carrier board is able to be connected to either a 3.3v logic level or a 5v logic level device. (Read our blog post if you have questions about logic level.)

This module is also available with a white-on-blue graphic display, or as a fully built kit with an included Seeeduino (Arduino Uno clone) loaded with code to demonstrate the graphic display.

The hardware design of this carrier board is open source. Under the Datasheets & Files tab is a downloadable zip file that contains everything you need to manufacture your own boards: Gerber files, PADs source schematic and layout, and full BOM. If you have any questions, please contact our knowledgeable and friendly support staff by email, phone, or chat.

Liquid Crystal monomers don’t have protein. Their chemical structures look like below. The effect of these chemicals shows in MSDS (Material Safety Data Sheet).

– In Proceedings of the National Academy of Sciences, Giesy’s research team assembled and analyzed a comprehensive list of 362 commonly used liquid crystal monomers gathered from 10 different industries and examined each chemical for its potential toxicity. When inhaled or ingested, these toxic chemicals can build up in the body over time with toxic effects, potentially causing digestive problems and other health issues.

-“These chemicals are semi-liquid and can get into the environment at any time during manufacturing and recycling, and they are vaporized during burning,” said University of Saskatchewan environmental toxicologist and lead author John Giesy in a press release. “Now we also know that these chemicals are being released by products just by using them.”

-The researchers found the specific monomers isolated from the smartphones were potentially hazardous to animals and the environment. In lab testing, the chemicals were found to have properties known to inhibit animals’ ability to digest nutrients and to disrupt the proper functioning of the gallbladder and thyroid–similar to dioxins and flame retardants which are known to cause toxic effects in humans and wildlife.

-To be clear, the researchers didn’t observe any adverse health effects from the accumulation of liquid crystals in the human body; they only found that these crystals do in fact leak from devices, and that they have the potential to be toxic. “We don’t know yet whether this a problem, but we do know that people are being exposed, and these chemicals have the potential to cause adverse effects,” said Giesy.

-Any artificial chemicals have potential hazard to human health. If you read the notes of your prescription drug, the statement is likely more alarming than above.

-If you crack LCD screens and find the liquid crystal leakage, don’t panic. Just remember that the liquid crystal materials might not be more toxic than your detergents for stove or washroom. Just wash your hands with soup throughout. Never try to play with it or even worse to taste it. The liquid of the cracked computer screen will not evaporate, no emissions worries.

-Any electronics has environment impact and can’t be used landfills. If you want to get rid of old LCD monitors or LCD TVs, give them to electronic collection stations. Let’s the professionals to handle them. They will extract some precious metals/parts and make them into something useful or at least not hazard. FYI, liquid crystal materials are retrievable.

Newhaven 16x2 character Liquid Crystal Display shows characters with bright red pixels on a black background when powered on. This transmissive LCD Display requires a backlight for visibility while offering a wide operating temperature range from -20 to 70 degrees Celsius. This NHD-0216K1Z-NSR-FBW-L display has an optimal view of 6:00. This display operates at 5V supply voltage and is RoHS compliant.

Adjust the length, position, and pinout of your cables or add additional connectors. Get a cable solution that’s precisely designed to make your connections streamlined and secure.

Easily modify any connectors on your display to meet your application’s requirements. Our engineers are able to perform soldering for pin headers, boxed headers, right angle headers, and any other connectors your display may require.

Choose from a wide selection of interface options or talk to our experts to select the best one for your project. We can incorporate HDMI, USB, SPI, VGA and more into your display to achieve your design goals.

Choose from a wide selection of changes including shape, size, pinout, and component layout of your PCB to make it a perfect fit for your application.

MoniServ, Inc.(lcdparts.net/lcdpart.com), we carry thousands of replacement parts  for all types of industrial LCD screens (LCD panels), such as the LCD screens for ATM, PLC,   Kiosks, POS, CNC machinery, Medical, Gaming, Digital signage, Avionic and other industrial applications. Varieties of LED backlight upgrade kits are also available! With simple tools, you can repair these expensive display assemblies at the fraction of the cost

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LCD panels are backlit by LED lights, so they rely on a backlight behind the panel to make the picture visible, and the LCD layer can"t prevent all light from escaping out of the screen. This means that even in a black scene, the backlight is still on, and some light escapes, causing blacks to appear gray.

In an attempt to mask this shortcoming, some LED TVs employ local dimming to target dark portions of the screen and dim the backlight in those areas. The intended result is that dark portions become darker, but everything else is left as bright as it should be, increasing the contrast between dark and light objects.

OLEDs use self-emitting pixels and don"t have a backlight, and because of this, they don"t have local dimming features. However, we score OLEDs as a perfect 10 for local dimming, because they do everything that a local dimming feature on an LED TV should do. Dark areas are completely off, leaving bright areas to stand out without any blooming.

Some TVs offer different local dimming settings. Low settings will usually dim the backlight less, but then the local dimming will also be less effective at improving the contrast. Higher settings will dim more, but may also make blooming, or other related issues, more visible. Local dimming preferences are subjective, so if you have multiple options, try out the different settings and choose the one you like best. Apart from that, there"s no way to get better results from local dimming. If this is a feature that matters to you, be sure to get a TV that scores highly in this test.

Contrast/Brightness: These settings aim to improve the contrast ratio by tinkering with the white and black levels. It doesn"t have a direct effect on the local dimming but can improve the picture quality. The contrast setting increases the luminosity of the brightest whites, while brightness (sometimes called black level), makes blacks darker. Keep in mind the brightness setting on some TVs controls the backlight, which doesn"t affect picture quality.

Samsung"s UHD Dimming: This processes the video in an attempt to mimic local dimming. It doesn’t dim the backlight but instead changes the contrast of different areas of the picture. Video purists usually dislike it, because it messes with the video settings of the TV, changing contrast from frame to frame. We don’t recommend using it.

Frame dimming: Frame dimming, or CE dimming on Samsung TVs, is a basic version of local dimming, but it dims the entire backlight instead of zones. Usually found on edge-lit TVs, it causes small highlights to become dim as well. It may improve the contrast a bit, but it"s not very useful for most scenes.

Local dimming features on LED TVs are a way to improve the contrast ratio. Since these TVs consist of LED backlights behind an LCD panel, local dimming aims to turn off, or dim, certain zones of the LED backlight, making blacks look darker and highlights brighter. However, there may be some issues with local dimming on some TVs as it could cause blooming around bright objects or for entire zones to light up when there"s a small object. Overall, most local dimming features on modern TV do an effective job at improving the picture quality in dark scenes, and only some lower-end models will have glaring problems.

Monitor displays are commonly used peripheral output devices in computers. These peripheral devices are also called ‘display monitors’ or ‘monitors’ or ‘displays’. They display information to a computer user.[1] There are a few important reasons why practicing radiologists should have a working knowledge of monitor displays and these are described below.

Impact of digital imaging: Computers play an important role in contemporary radiology practice. Most radiology modalities today use monitor displays to aid analysis of images. Monitors have become integral components of digital radiography, USG, CT / MRI consoles and workstations, and PACS terminals.

Image chain: There is an image chain that radiologists need to be aware of while working on computers with monitor displays. At one end of the image chain is the modality. Here pixels, gray scale values, processing, postprocessing, and window level and width are important parameters that govern the appearance of any given image. In the middle of the image chain is the computer with its display controller, graphic cards, and look-up tables (LUT) memory, which influence the digital generation of an image. The human observer"s visual system is the final element of the image chain. Its performance is strongly affected by ambient light, environment, reflection, veiling glare, angular response, and visual acuity.

Shift in analysis model: In the traditional model of radiology practice, hardcopy images displayed on viewboxes were the first point of analysis. Today, in most instances, softcopy images displayed on monitors are the first point of analysis. As a result, key steps like viewing, analysis, processing, and postprocessing of softcopy images are executed directly at monitors of consoles, workstations, and office desktops.[2]

Heterogeneity of data: The data displayed on the monitors in a radiology department is heterogeneous. It is often a variable combination of monochrome and gray-scale and/or color images viewed alongside text, audio, and/or video.[3] In such circumstances, radiologists need to possess a working knowledge of important performance parameters like resolution, brightness, contrast ratio, and viewing angles.

Growth of RIS, PACS, and teleradiology: Image transfer across a variety of networks and radiology modalities is common practice these days. Images are increasingly being stored as part of a patient"s electronic medical records, to be analyzed as and when required; images are often transferred over departmental networks and to teleradiology workstations for analysis[3] In such a diverse set of locations, it is common to find different types of monitors used for displaying assorted types of data.

Original dataset: The American College of Radiology (ACR) has devised guidelines for monitor displays, based on the matrix size of the original digital image dataset. Monitors for small matrix datasets [typically sourced from CT, MRI, USG, nuclear medicine (NM), digital fluorography, and digital subtraction angiography (DSA)] have different performance guidelines as compared to monitors required for large matrix datasets [e.g., sourced from digital radiography (DR), computed radiography (CR), digitized films, and digital mammography][4]. The large matrix datasets require monitors with higher performance. As a rule of thumb, the resolution of the selected display system, ideally, should match the matrix of the image acquisition data.[4]

Image consistency: Each and every computer and its monitor at our workplace, handles gray-scale images in a different way. This is governed by factors such as acquisition parameters, application technique, graphics board, video board memory and processing, LUTs, and display signal processing. Therefore, there is a growing awareness of the need to maintain image consistency and gray-scale calibration across a broad variety of monitor displays.[5]

Ever had your TV showing nothing but a black screen even if the audio was working? Unfortunately, that’s a common issue with low/middle-end LCD/LED TVs these days… Even more frustrating, this issue often comes from a rather tiny and cheap component that can be easily replaced. Most common issues are:

One of my relatives had this exact symptom happening all of a sudden. This problem on low-end TVs often occurs within the first couple years. As the repair costs for that kind of TV is pretty low, considering repairing it yourself might be a good idea!

The first step into repair is to find the root cause of the issue. As backlight failure is a very common issue, this is the first thing to test. To do so, the easiest way is to power on your screen, put a flashlight very close to it and check if you can see the image through. The image would be very dark, like turning the brightness of the screen very very low.

That implies disassembling the TV to access the backlight which is between the LCD screen in the front and the boards in the rear. In my case, with a Samsung F5000, I had to process as follows:

First we have to remove the back housing to reveal the boards (from left to right: main board, T-CON, power supply) and disconnect the LCD panel from the T-CON board.

Note: Older TVs have neon tubes for backlight, which is thicker and less exposed to this kind of failure. LED backlight is the most common thing these days, but do not mistake an LED TV with an OLED TV. The first one is a classic LCD panel with a LED backlight, whereas the second is an OLED panel that doesn’t need any backlight as it is integrated in each pixels (making the spare parts much more expensive by the way).

As we can see, the backlight system is made of 5 LED strips. First thing to do is look for burnt LEDs. Most LED backlight systems have strips set in series, meaning that if one of the them fails, all the system goes dark…

Using a multimeter, we can confirm that the strips are indeed set in series, so now we have to test each strip individually. Professionals use LED testers such as this one (about 40$ on amazon) but as I didn’t had one at the time, I decided to make one, McGyver style!