used lcd panel for tv free sample
Wholesalers on Alibaba.com have a wide range of functions and such a curved monitorphone. LEDs are an excellent choice for smart watches as they are wireless and have a built-in Light-emitting Diode (LAG)) for the convenience of large-sized ones, LEDs are equipped with all the functions as a curved monitorphone, and it has a built-in media player and the possibility to see a difference in the second-hand TV of the choice. LED smart watches are wirelessly designed and allow the user to see the image in all, and they"re looking great for them.
With all the advantages and disadvantages, lcdds are essentially a good choice for those who see the TV starting from 4k smartphone. Nowadays, in addition to the wholesale models, lcdds are essentially a good option for those that don ’ t have the capacity of a device.
Dirty Screen Effect is a term and acronym often tossed around by TV reviewers and A/V forum enthusiasts as if everyone knows what it is. And, yet, very few folks have ever heard of it before. You may have seen it, though. In fact, if you’ve recently purchased a TV and it doesn’t look quite right, your TV might be suffering from Dirty Screen Effect, more commonly referred to as DSE.
In this quick guide we’ll cover what Dirty Screen Effect looks like, what’s happening on a technical level, and what, if anything, you can do to get rid of it. We’ll also touch on the notion of the so-called “panel lottery” and how that plays into how clean — or dirty — your new TV screen might look.
Dirty Screen Effect (DSE) is a term that’s used to describe an LCD panel that has inconsistent luminance performance across its surface area. It can appear as random splotches, uniform lines, wide bars, and, in some cases, vignetting (a slight darkening toward the corners). DSE once plagued plasma TV panels as well. But since those are no longer in production, we’ll keep this explainer focused on LCD-based TVs.
As a reminder, any TV that uses an LED backlight also uses an LCD panel, so TVs marketed as LED, QLED, and mini-LED are all susceptible. Due to what causes DSE on a technical level, some may argue it can only apply to LCD-based TVs. However, similar effects can be seen in OLED-based displays — thus the term is often applied — so we’ll include those types of TVs as well, but address them separately.
While DSE can be seen in any number of scenarios, you are most likely to see it when there are big swatches of the same color on the screen. Take an ice hockey game, for example. Some areas of the ice will appear to be dingier or darker than other areas of the ice. You might also see DSE more easily when watching golf; when there are vast sections of grass on the screen, some parts of the grass may appear to be darker or more muted in color than other parts.
Some DSE is severe and some is so faint you may not notice it unless you look hard for it. As a very clear example of what DSE looks like when exposed by testing slides, we’ve included an example below.
There are a number of factors stemming from the manufacturing of an LCD panel that can cause Dirty Screen Effect, from variance in backlight distribution to variance in TFT switching for sub-pixels, to variance in conductivity and/or capacitance of transparent electrodes. That’s super-nerdy, though, and the actual cause is less important than the common theme here: inconsistency.
In panel manufacturing, there are numerous variables that can be introduced that would cause an LCD panel to have groups of pixels that shine less bright than others. This variance is, unfortunately, part of the tech that makes our TVs. And the manner in which different manufacturers handle that variance is also … you guessed it: Varied.
Dirty Screen Effect also can be caused by damage to the panel in shipping or mishandling of the TV during the setup or installation process. Generally speaking, it’s recommended one avoids “pinching” or otherwise exerting pressure on the front of the TV screen.
This is a difficult question to answer because I do not have data that supports objective analysis on the prevalence of DSE in newly manufactured televisions. However, I can offer some anecdotal perspective based on my experience as a TV reviewer and the feedback I get from readers and viewers, as well as reports I see in A/V forums.
From what I’ve seen, DSE — ranging from insignificant to severe — seems fairly common among newly manufactured LCD-based televisions, due primarily to the nature of LCD panel manufacturing. Very broadly, the less expensive a TV is, the more likely it is to exhibit some level of DSE. More expensive TVs are not immune to the issue, but some manufacturers have tighter quality assurance tolerances for their high-end products so — again, very broadly speaking — DSE tends to be less prevalent among those models.
DSE as a symptom of age is virtually impossible to track, however — again, anecdotally — I have witnessed DSE creep into a TV’s display panel slowly over time and worsen with age. I’ve seen it happen in TVs I own, TVs friends and family have owned, and TVs installed in commercial environments such as hotels and bars.
First, a warning: Once you see DSE on your TV, it’s tough to “un-see.” So, if you are happy with your TV’s performance and wish to stay that way, then you may wish to subscribe to the “ignorance is bliss” theory and forego the following tests.
If, however, you suspect that your new TV may have levels of DSE that you deem to be unacceptable, you can use this YouTube video (also posted at the top of this article) to look for signs of DSE. In our video, we not only provide testing slides that help to expose DSE, but guide you on how to spot it.
Unfortunately, there’s no way to eliminate DSE. Some websites suggest loosening the screws on the back of a TV to lessen the strain on the panel. We do not recommend this tactic as it could stand to void an active warranty. Also, it’s not very likely to work.
Really, the best way to get rid of DSE on a newly purchased TV is to catch it early and return or exchange the TV within the typical 30-day customer satisfaction period. It is rare for a manufacturer’s warranty to cover a repair or replacement when the complaint is over a flaw that the said manufacturer has already deemed to be within an acceptable margin of error.
Most TVs offer a “game mode” which, due to its tendency to brighten everything on-screen, can help to obscure DSE. But this is really just a Band-Aid measure. The DSE is still there, but it may be less obvious. Another somewhat helpful tip to reduce the appearance of DSE in LCD panels is to view the TV from as direct an angle as possible. As you move off-axis (view a TV from an angle) DSE tends to become more obvious.
In very limited instances, some cases of DSE on OLED TVs can be remedied by manually triggering the TV’s built-in “pixel refresh” system, usually located somewhere in the TV’s system menu.
The so-called “panel lottery” refers to the game TV buyers unwittingly play when purchasing a TV. Sometimes you “win the panel lottery,” which is a way of saying that the TV you got was in especially pristine shape and shows no signs of DSE. It’s also a term used to easily express that there’s such a variance in panel quality that it’s virtually impossible you’ll win a perfect panel. In other words, it’s all up to chance.
Shopping for a new TV is like wading through a never-ending pool of tech jargon, display terminology, and head-spinning acronyms. It was one thing when 4K resolution landed in the homes of consumers, with TV brands touting the new UHD viewing spec as a major marketing grab. But over the last several years, the plot has only continued to thicken when it comes to three- and four-letter acronyms with the introduction of state-of-the-art lighting and screen technology. But between OLEDs, QLEDs, mini-LEDs, and now QD-OLEDs, there’s one battle of words that rests at the core of TV vocabulary: LED versus LCD.
Despite having a different acronym, LED TV is just a specific type of LCD TV, which uses a liquid crystal display (LCD) panel to control where light is displayed on your screen. These panels are typically composed of two sheets of polarizing material with a liquid crystal solution between them. When an electric current passes through the liquid, it causes the crystals to align, so that light can (or can’t) pass through. Think of it as a shutter, either allowing light to pass through or blocking it out.
Since both LED and LCD TVs are based around LCD technology, the question remains: what is the difference? Actually, it’s about what the difference was. Older LCD TVs used cold cathode fluorescent lamps (CCFLs) to provide lighting, whereas LED LCD TVs used an array of smaller, more efficient light-emitting diodes (LEDs) to illuminate the screen.
Since the technology is better, all LCD TVs now use LED lights and are colloquially considered LED TVs. For those interested, we’ll go deeper into backlighting below, or you can move onto the Local Dimming section.
Three basic illumination forms have been used in LCD TVs: CCFL backlighting, full-array LED backlighting, and LED edge lighting. Each of these illumination technologies is different from one another in important ways. Let’s dig into each.
CCFL backlighting is an older, now-abandoned form of display technology in which a series of cold cathode lamps sit across the inside of the TV behind the LCD. The lights illuminate the crystals fairly evenly, which means all regions of the picture will have similar brightness levels. This affects some aspects of picture quality, which we discuss in more detail below. Since CCFLs are larger than LED arrays, CCFL-based LCD TVs are thicker than LED-backlit LCD TVs.
Full-array backlighting swaps the outdated CCFLs for an array of LEDs spanning the back of the screen, comprising zones of LEDs that can be lit or dimmed in a process called local dimming. TVs using full-array LED backlighting to make up a healthy chunk of the high-end LED TV market, and with good reason — with more precise and even illumination, they can create better picture quality than CCFL LCD TVs were ever able to achieve, with better energy efficiency to boot.
Another form of LCD screen illumination is LED edge lighting. As the name implies, edge-lit TVs have LEDs along the edges of a screen. There are a few different configurations, including LEDs along just the bottom, LEDs on the top and bottom, LEDs left and right, and LEDs along all four edges. These different configurations result in picture quality differences, but the overall brightness capabilities still exceed what CCFL LCD TVs could achieve. While there are some drawbacks to edge lighting compared to full-array or direct backlight displays, the upshot is edge lighting that allows manufacturers to make thinner TVs that cost less to manufacture.
To better close the local-dimming quality gap between edge-lit TVs and full-array back-lit TVs, manufacturers like Sony and Samsung developed their own advanced edge lighting forms. Sony’s technology is known as “Slim Backlight Master Drive,” while Samsung has “Infinite Array” employed in its line of QLED TVs. These keep the slim form factor achievable through edge-lit design and local dimming quality more on par with full-array backlighting.
Local dimming is a feature of LED LCD TVs wherein the LED light source behind the LCD is dimmed and illuminated to match what the picture demands. LCDs can’t completely prevent light from passing through, even during dark scenes, so dimming the light source itself aids in creating deeper blacks and more impressive contrast in the picture. This is accomplished by selectively dimming the LEDs when that particular part of the picture — or region — is intended to be dark.
Local dimming helps LED/LCD TVs more closely match the quality of modern OLED displays, which feature better contrast levels by their nature — something CCFL LCD TVs couldn’t do. The quality of local dimming varies depending on which type of backlighting your LCD uses, how many individual zones of backlighting are employed, and the quality of the processing. Here’s an overview of how effective local dimming is on each type of LCD TV.
TVs with full-array backlighting have the most accurate local dimming and therefore tend to offer the best contrast. Since an array of LEDs spans the entire back of the LCD screen, regions can generally be dimmed with more finesse than on edge-lit TVs, and brightness tends to be uniform across the entire screen. Hisense’s impressive U7G TVs are great examples of relatively affordable models that use multiple-zone, full-array backlighting with local dimming.
“Direct local dimming” is essentially the same thing as full-array dimming, just with fewer LEDs spread further apart in the array. However, it’s worth noting that many manufacturers do not differentiate “direct local dimming” from full-array dimming as two separate forms of local dimming. We still feel it’s important to note the difference, as fewer, further-spaced LEDs will not have the same accuracy and consistency as full-array displays.
Because edge lighting employs LEDs positioned on the edge or edges of the screen to project light across the back of the LCD screen, as opposed to coming from directly behind it, it can result in very subtle blocks or bands of lighter pixels within or around areas that should be dark. The local dimming of edge-lit TVs can sometimes result in some murkiness in dark areas compared with full-array LED TVs. It should also be noted that not all LED edge-lit TVs offer local dimming, which is why it is not uncommon to see glowing strips of light at the edges of a TV and less brightness toward the center of the screen.
Since CCFL backlit TVs do not use LEDs, models with this lighting style do not have dimming abilities. Instead, the LCD panel of CCFL LCDs is constantly and evenly illuminated, making a noticeable difference in picture quality compared to LED LCDs. This is especially noticeable in scenes with high contrast, as the dark portions of the picture may appear too bright or washed out. When watching in a well-lit room, it’s easier to ignore or miss the difference, but in a dark room, it will be, well, glaring.
An OLED display uses a panel of pixel-sized organic compounds that respond to electricity. Since each tiny pixel (millions of which are present in modern displays) can be turned on or off individually, OLED displays are called “emissive” displays (meaning they require no backlight). They offer incredibly deep contrast ratios and better per-pixel accuracy than any other display type on the market.
Because they don’t require a separate light source, OLED displays are also amazingly thin — often just a few millimeters. OLED panels are often found on high-end TVs in place of LED/LCD technology, but that doesn’t mean that LED/LCDs aren’t without their own premium technology.
QLED is a premium tier of LED/LCD TVs from Samsung. Unlike OLED displays, QLED is not a so-called emissive display technology (lights still illuminate QLED pixels from behind). However, QLED TVs feature an updated illumination technology over regular LED LCDs in the form of Quantum Dot material (hence the “Q” in QLED), which raises overall efficiency and brightness. This translates to better, brighter grayscale and color and enhances HDR (High Dynamic Range) abilities.
And now to make things extra confusing, part of Samsung’s 2022 TV lineup is being billed as traditional OLEDs, although a deeper dive will reveal this is actually the company’s first foray into a new panel technology altogether called QD-OLED.
For a further description of QLED and its features, read our list of the best TVs you can buy. The article further compares the qualities of both QLED and OLED TV; however, we also recommend checking outfor a side-by-side look at these two top-notch technologies.
There are more even displays to become familiar with, too, including microLED and Mini-LED, which are lining up to be the latest head-to-head TV technologies. Consider checking out how the two features compare to current tech leaders in
In the world of TV technology, there’s never a dull moment. However, with this detailed research, we hope you feel empowered to make an informed shopping decision and keep your Best Buy salesperson on his or her toes.
Many Apple products use liquid crystal displays (LCD). LCD technology uses rows and columns of addressable points (pixels) that render text and images on the screen. Each pixel has three separate subpixels—red, green and blue—that allow an image to render in full color. Each subpixel has a corresponding transistor responsible for turning that subpixel on and off.
Depending on the display size, there can be thousands or millions of subpixels on the LCD panel. For example, the LCD panel used in the iMac (Retina 5K, 27-inch, 2019) has a display resolution of 5120 x 2880, which means there are over 14.7 million pixels. Each pixel is made up of a red, a green, and a blue subpixel, resulting in over 44 million individual picture elements on the 27-inch display. Occasionally, a transistor may not work perfectly, which results in the affected subpixel remaining off (dark) or on (bright). With the millions of subpixels on a display, it is possible to have a low number of such transistors on an LCD. In some cases a small piece of dust or other foreign material may appear to be a pixel anomaly. Apple strives to use the highest quality LCD panels in its products, however pixel anomalies can occur in a small percentage of panels.
In many cases pixel anomalies are caused by a piece of foreign material that is trapped somewhere in the display or on the front surface of the glass panel. Foreign material is typically irregular in shape and is usually most noticeable when viewed against a white background. Foreign material that is on the front surface of the glass panel can be easily removed using a lint free cloth. Foreign material that is trapped within the screen must be removed by an Apple Authorized Service Provider or Apple Retail Store.
If you are concerned about pixel anomalies on your display, take your Apple product in for closer examination at an Apple Store, Apple Authorized Service Provider, or an Independent Repair Provider. There may be a charge for the evaluation. Genuine Apple parts are also available for out-of-warranty repairs through Self Service Repair.*
The Hisense U8H matches the excellent brightness and color performance of much pricier LCD TVs, and its Google TV smart platform is a welcome addition. But it’s available in only three screen sizes.
The Hisense U8H is the best LCD/LED TV for most people because it delivers the performance of a much pricier TV yet starts at under $1,000, for the smallest (55-inch) screen size. This TV utilizes quantum dots, a full-array backlight with mini-LEDs, and a 120 Hz refresh rate to deliver a great-looking 4K HDR image. It’s compatible with every major HDR format. And it’s equipped with two full-bandwidth HDMI 2.1 inputs to support 4K 120 Hz gaming from the newest Xbox and PlayStation consoles. Add in the intuitive, fully featured Google TV smart-TV platform, and the U8H’s price-to-performance ratio is of inarguable value.
Chief among the U8H’s many strengths is its impressive peak brightness. When sending it HDR test patterns, I measured an average brightness of 1,500 nits, with peaks just north of 1,800 nits (a measurement of luminance; see TV features, defined for more info). To put that into perspective, consider that the 65-inch version of our budget 4K TV pick (the TCL 5-Series) typically costs around half as much as the 65-inch U8H but achieves only around 30% to 40% of its brightness. On the other side of the coin, the 65-inch version of our upgrade pick (the Samsung QN90B) costs almost twice as much as the 65-inch U8H, but it achieves only nominally higher brightness. Adequate light output creates convincing highlights and image contrast and (when necessary) combats ambient light from lamps or windows. It is a necessity for any TV worth buying—especially if you hope to watch HDR movies or play HDR games—and the U8H simply outpaces most TVs in its price range (and some in the next price bracket up, too).
Key to this functionality is the U8H’s employment of mini-LED backlighting with local dimming, which allows this TV to produce very bright light while still maintaining satisfyingly deep black levels that are typically free of blooming (or light bleed that’s visible around bright objects against a dark backdrop). This not only ensures impressive image contrast, it also makes the U8H a viable choice for most rooms, whether they’re brighter than average or dimmed down like a movie theater.
That’s not to say the U8H has pixel-precise light control—it’s not an OLED TV, after all—but it does a terrific job most of the time. In fact, in our tests, the U8H bested last year’s upgrade pick, the Samsung QN90A, in certain scenarios: The intro to Guillermo del Toro’s Cabinet of Curiosities on Netflix features the filmmaker against a pitch-black backdrop. Though last year’s QN90A failed to maintain perfect control over dimming elements during this scene (the black backdrop brightened distractingly once a sufficient amount of brighter content appeared on screen), the U8H did not. (For the record, the newer QN90B also passed this test.) The U8H’s mini-LEDs also help the screen look uniformly bright: Although the U8H is still not as good as an OLED TV in this respect, it shows very little indication of being a backlight-driven display, even during tricky scenes with large swaths of dim lighting.
The U8H’s brightness, black-level integrity, and local-dimming abilities make this an excellent TV for watching HDR content. The U8H is capable of playing HDR content in all of the major formats (HDR10, HDR10+, Dolby Vision, and HLG), but when it comes to impressive HDR, what’s under the hood is much more important than format compatibility. The most crucial thing for good HDR is high brightness and deep color saturation, and the U8H’s quantum dots achieve the latter. It’s not as simple as just having quantum dots, however: While many TVs (even the budget options) have quantum dots nowadays, what is often not taken into account is that brightness directly affects color saturation. For example, both the 2022 TCL 6-Series and the Hisense U8H are equipped with quantum dots, mini-LED backlights, and local dimming. But because the U8H is notably brighter than the 6-Series, it also achieves a higher total color volume. During our color-volume testing, the U8H exhibited color ranges at more than 100% of the DCI-P3 color space (the range of color needed to properly display HDR content), and it is capable of roughly 10% more total color volume compared with the 6-Series.
What does this mean in real-world terms? It means that the Hisense U8H truly excels as a modern 4K HDR TV, whether you’re watching the latest episode of Rings of Power or playing Overwatch 2. While watching HDR content side by side on the U8H and on our upgrade pick, the Samsung QN90B, I was truly surprised by how similar they looked at times, given that our upgrade pick is much more expensive. That said, though the U8H achieves impressive results where light output and color volume are concerned, it also exhibited some occasional video processing and upscaling issues (see Flaws but not dealbreakers), which videophiles and AV enthusiasts may take umbrage with. But in general, the picture quality punches well above its weight, metaphorically speaking.
And thanks to Hisense’s inclusion of Filmmaker Mode, it’s easy to rein in the U8H’s brightness abilities for a more-subdued and filmic experience in a darker room. Our measurements revealed that this mode has a very accurate white balance, mostly accurate colors (green is a bit oversaturated, but not egregiously so), and a perfect “dark room” gamma (which controls how quickly the video signal transitions from dark to light). Additionally, the TV’s 120 Hz refresh rate means it can play Blu-ray discs at 24 fps without the judder that’s usually present on TVs with 60 Hz refresh rates.
The TV’s higher refresh rate also reduces motion blur in faster-moving sports and allows for smoother, more stable motion in games. Two of the four HDMI inputs support 4K gaming at 120 Hz. The U8H measured low input lag while playing in 4K resolution, and Hisense’s helpful GameZone setting in the picture menu allowed me to confirm the presence of 120 Hz playback and variable refresh rate during games.
The onboard Google TV smart platform is another feather in this TV’s cap. As usual, however, it will be much more satisfying to use if you have a Google account and already take advantage of Google’s connected services, like Photos. The experience of navigating the TV’s smart features—scanning QR codes to sign into apps, using the onscreen keyboard, and browsing your Google Photos to set a photo as a screensaver—was very satisfying in terms of responsiveness and speed. Powering on the TV and booting into an app took just seconds. The included Bluetooth remote is also equipped with a handy “Hey Google” button, allowing you to pull up Google’s assistant and use voice commands to search for content or set a reminder. If you have multiple users with their own Google accounts, you can designate separate profiles (attached to a Gmail account) so that each user can customize the experience to their liking, as well as access their own Google Drive or Photos. While some reviewers have reported instances of momentary freezing while using the U8H’s platform, I didn’t personally experience any instances of slowdown that were egregiously worse than with any other smart-TV platform.
In terms of design, the Hisense U8H is not as svelte as our upgrade pick, but it’s plenty sturdy and doesn’t look or feel cheap. Two narrow, metal feet jut out from beneath the panel and steadily hold the TV. They can be attached in two separate spots, either closer in toward the middle of the panel or out toward the edges, to account for different-size TV stands. The feet are also equipped with cable organization clasps—a nice touch for keeping your TV stand free of cable clutter. Though the TV is primarily plastic, its bezels are lined with metal strips, providing a bit more durability in the long run. I moved it around my home, and it was no worse for wear, but we’ll know more after doing some long-term testing.
The Hisense U8H has some difficulties with banding, or areas of uneven gradation, where transitions that should appear smooth instead look like “bands” of color (sometimes also called posterization). Like many current 4K HDR TVs, the U8H uses an 8-bit panel rather than a 10-bit panel, which affects the color decoding and color presentation process. This is usually relevant only with HDR video and games. When playing games on the PlayStation 5 and Xbox Series X, I saw a few instances where the content wasn’t rendered correctly and displayed ugly splotches of color on the screen. However, this almost always occurred during static screens (such as a pause menu or loading screen); I rarely spotted it during actual gameplay. Hisense has stated that it would address the problem in a future firmware update, but at the time of writing it was still present. This is a flaw that may give dedicated gamers pause, but we don’t consider it to be a dealbreaker for most people.
I also saw occasional instances of banding with TV shows and movies, though they were few and far between. The U8H isn’t the best at upscaling sub-4K content, so videos with a 1080p or lower resolution looked a little soft. You can get better overall video processing and upscaling by springing for our upgrade pick (this is one reason it’s more expensive, after all).
Although the UH8 TV has four HDMI inputs, only two of them are fully HDMI 2.1–compatible. And one of those is designated as the eARC input (intended as an audio connection for a soundbar or AV receiver connection). So if you’re pairing an external audio system with the U8H, you may have only one input remaining that can support HDMI 2.1 features like 4K 120 Hz playback, variable refresh rate, and auto game mode; this could be a dealbreaker if you own more than one current-gen gaming console. If you’re in that boat, you may want to splash out some extra dough for our upgrade pick. Additionally, folks using pre-HDMI source devices—like the five-cable composite connector with green, red, blue, and red/white audio inputs—should be aware that this TV requires an adapter to allow those devices to connect, and an adapter is not included in the box.
Finally, like most TVs that use vertical alignment (VA) LCD panels, the U8H has a limited horizontal viewing angle, which may be a bit annoying if you’re hoping to entertain a large crowd. Our upgrade pick uses a special wide-angle technology to address this.
For gaming, use the game picture mode (the TV should switch into this mode automatically when paired with the newer game consoles), and then go into the Gaming submenu to make sure the right settings (VRR) are enabled. We recommend leaving the HDMI setting in “auto,” unless you notice that your game console is incorrectly identified.
Glass substrate with ITO electrodes. The shapes of these electrodes will determine the shapes that will appear when the LCD is switched ON. Vertical ridges etched on the surface are smooth.
A liquid-crystal display (LCD) is a flat-panel display or other electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizers. Liquid crystals do not emit light directlybacklight or reflector to produce images in color or monochrome.seven-segment displays, as in a digital clock, are all good examples of devices with these displays. They use the same basic technology, except that arbitrary images are made from a matrix of small pixels, while other displays have larger elements. LCDs can either be normally on (positive) or off (negative), depending on the polarizer arrangement. For example, a character positive LCD with a backlight will have black lettering on a background that is the color of the backlight, and a character negative LCD will have a black background with the letters being of the same color as the backlight. Optical filters are added to white on blue LCDs to give them their characteristic appearance.
LCDs are used in a wide range of applications, including LCD televisions, computer monitors, instrument panels, aircraft cockpit displays, and indoor and outdoor signage. Small LCD screens are common in LCD projectors and portable consumer devices such as digital cameras, watches, calculators, and mobile telephones, including smartphones. LCD screens have replaced heavy, bulky and less energy-efficient cathode-ray tube (CRT) displays in nearly all applications. The phosphors used in CRTs make them vulnerable to image burn-in when a static image is displayed on a screen for a long time, e.g., the table frame for an airline flight schedule on an indoor sign. LCDs do not have this weakness, but are still susceptible to image persistence.
Each pixel of an LCD typically consists of a layer of molecules aligned between two transparent electrodes, often made of Indium-Tin oxide (ITO) and two polarizing filters (parallel and perpendicular polarizers), the axes of transmission of which are (in most of the cases) perpendicular to each other. Without the liquid crystal between the polarizing filters, light passing through the first filter would be blocked by the second (crossed) polarizer. Before an electric field is applied, the orientation of the liquid-crystal molecules is determined by the alignment at the surfaces of electrodes. In a twisted nematic (TN) device, the surface alignment directions at the two electrodes are perpendicular to each other, and so the molecules arrange themselves in a helical structure, or twist. This induces the rotation of the polarization of the incident light, and the device appears gray. If the applied voltage is large enough, the liquid crystal molecules in the center of the layer are almost completely untwisted and the polarization of the incident light is not rotated as it passes through the liquid crystal layer. This light will then be mainly polarized perpendicular to the second filter, and thus be blocked and the pixel will appear black. By controlling the voltage applied across the liquid crystal layer in each pixel, light can be allowed to pass through in varying amounts thus constituting different levels of gray.
The chemical formula of the liquid crystals used in LCDs may vary. Formulas may be patented.Sharp Corporation. The patent that covered that specific mixture expired.
Most color LCD systems use the same technique, with color filters used to generate red, green, and blue subpixels. The LCD color filters are made with a photolithography process on large glass sheets that are later glued with other glass sheets containing a TFT array, spacers and liquid crystal, creating several color LCDs that are then cut from one another and laminated with polarizer sheets. Red, green, blue and black photoresists (resists) are used. All resists contain a finely ground powdered pigment, with particles being just 40 nanometers across. The black resist is the first to be applied; this will create a black grid (known in the industry as a black matrix) that will separate red, green and blue subpixels from one another, increasing contrast ratios and preventing light from leaking from one subpixel onto other surrounding subpixels.Super-twisted nematic LCD, where the variable twist between tighter-spaced plates causes a varying double refraction birefringence, thus changing the hue.
LCD in a Texas Instruments calculator with top polarizer removed from device and placed on top, such that the top and bottom polarizers are perpendicular. As a result, the colors are inverted.
The optical effect of a TN device in the voltage-on state is far less dependent on variations in the device thickness than that in the voltage-off state. Because of this, TN displays with low information content and no backlighting are usually operated between crossed polarizers such that they appear bright with no voltage (the eye is much more sensitive to variations in the dark state than the bright state). As most of 2010-era LCDs are used in television sets, monitors and smartphones, they have high-resolution matrix arrays of pixels to display arbitrary images using backlighting with a dark background. When no image is displayed, different arrangements are used. For this purpose, TN LCDs are operated between parallel polarizers, whereas IPS LCDs feature crossed polarizers. In many applications IPS LCDs have replaced TN LCDs, particularly in smartphones. Both the liquid crystal material and the alignment layer material contain ionic compounds. If an electric field of one particular polarity is applied for a long period of time, this ionic material is attracted to the surfaces and degrades the device performance. This is avoided either by applying an alternating current or by reversing the polarity of the electric field as the device is addressed (the response of the liquid crystal layer is identical, regardless of the polarity of the applied field).
Displays for a small number of individual digits or fixed symbols (as in digital watches and pocket calculators) can be implemented with independent electrodes for each segment.alphanumeric or variable graphics displays are usually implemented with pixels arranged as a matrix consisting of electrically connected rows on one side of the LC layer and columns on the other side, which makes it possible to address each pixel at the intersections. The general method of matrix addressing consists of sequentially addressing one side of the matrix, for example by selecting the rows one-by-one and applying the picture information on the other side at the columns row-by-row. For details on the various matrix addressing schemes see passive-matrix and active-matrix addressed LCDs.
LCDs are manufactured in cleanrooms borrowing techniques from semiconductor manufacturing and using large sheets of glass whose size has increased over time. Several displays are manufactured at the same time, and then cut from the sheet of glass, also known as the mother glass or LCD glass substrate. The increase in size allows more displays or larger displays to be made, just like with increasing wafer sizes in semiconductor manufacturing. The glass sizes are as follows:
Until Gen 8, manufacturers would not agree on a single mother glass size and as a result, different manufacturers would use slightly different glass sizes for the same generation. Some manufacturers have adopted Gen 8.6 mother glass sheets which are only slightly larger than Gen 8.5, allowing for more 50 and 58 inch LCDs to be made per mother glass, specially 58 inch LCDs, in which case 6 can be produced on a Gen 8.6 mother glass vs only 3 on a Gen 8.5 mother glass, significantly reducing waste.AGC Inc., Corning Inc., and Nippon Electric Glass.
In 1922, Georges Friedel described the structure and properties of liquid crystals and classified them in three types (nematics, smectics and cholesterics). In 1927, Vsevolod Frederiks devised the electrically switched light valve, called the Fréedericksz transition, the essential effect of all LCD technology. In 1936, the Marconi Wireless Telegraph company patented the first practical application of the technology, "The Liquid Crystal Light Valve". In 1962, the first major English language publication Molecular Structure and Properties of Liquid Crystals was published by Dr. George W. Gray.RCA found that liquid crystals had some interesting electro-optic characteristics and he realized an electro-optical effect by generating stripe-patterns in a thin layer of liquid crystal material by the application of a voltage. This effect is based on an electro-hydrodynamic instability forming what are now called "Williams domains" inside the liquid crystal.
In the late 1960s, pioneering work on liquid crystals was undertaken by the UK"s Royal Radar Establishment at Malvern, England. The team at RRE supported ongoing work by George William Gray and his team at the University of Hull who ultimately discovered the cyanobiphenyl liquid crystals, which had correct stability and temperature properties for application in LCDs.
The idea of a TFT-based liquid-crystal display (LCD) was conceived by Bernard Lechner of RCA Laboratories in 1968.dynamic scattering mode (DSM) LCD that used standard discrete MOSFETs.
On December 4, 1970, the twisted nematic field effect (TN) in liquid crystals was filed for patent by Hoffmann-LaRoche in Switzerland, (Swiss patent No. 532 261) with Wolfgang Helfrich and Martin Schadt (then working for the Central Research Laboratories) listed as inventors.Brown, Boveri & Cie, its joint venture partner at that time, which produced TN displays for wristwatches and other applications during the 1970s for the international markets including the Japanese electronics industry, which soon produced the first digital quartz wristwatches with TN-LCDs and numerous other products. James Fergason, while working with Sardari Arora and Alfred Saupe at Kent State University Liquid Crystal Institute, filed an identical patent in the United States on April 22, 1971.ILIXCO (now LXD Incorporated), produced LCDs based on the TN-effect, which soon superseded the poor-quality DSM types due to improvements of lower operating voltages and lower power consumption. Tetsuro Hama and Izuhiko Nishimura of Seiko received a US patent dated February 1971, for an electronic wristwatch incorporating a TN-LCD.
In 1972, the concept of the active-matrix thin-film transistor (TFT) liquid-crystal display panel was prototyped in the United States by T. Peter Brody"s team at Westinghouse, in Pittsburgh, Pennsylvania.Westinghouse Research Laboratories demonstrated the first thin-film-transistor liquid-crystal display (TFT LCD).high-resolution and high-quality electronic visual display devices use TFT-based active matrix displays.active-matrix liquid-crystal display (AM LCD) in 1974, and then Brody coined the term "active matrix" in 1975.
In 1972 North American Rockwell Microelectronics Corp introduced the use of DSM LCDs for calculators for marketing by Lloyds Electronics Inc, though these required an internal light source for illumination.Sharp Corporation followed with DSM LCDs for pocket-sized calculators in 1973Seiko and its first 6-digit TN-LCD quartz wristwatch, and Casio"s "Casiotron". Color LCDs based on Guest-Host interaction were invented by a team at RCA in 1968.TFT LCDs similar to the prototypes developed by a Westinghouse team in 1972 were patented in 1976 by a team at Sharp consisting of Fumiaki Funada, Masataka Matsuura, and Tomio Wada,
In 1983, researchers at Brown, Boveri & Cie (BBC) Research Center, Switzerland, invented the passive matrix-addressed LCDs. H. Amstutz et al. were listed as inventors in the corresponding patent applications filed in Switzerland on July 7, 1983, and October 28, 1983. Patents were granted in Switzerland CH 665491, Europe EP 0131216,
The first color LCD televisions were developed as handheld televisions in Japan. In 1980, Hattori Seiko"s R&D group began development on color LCD pocket televisions.Seiko Epson released the first LCD television, the Epson TV Watch, a wristwatch equipped with a small active-matrix LCD television.dot matrix TN-LCD in 1983.Citizen Watch,TFT LCD.computer monitors and LCD televisions.3LCD projection technology in the 1980s, and licensed it for use in projectors in 1988.compact, full-color LCD projector.
In 1990, under different titles, inventors conceived electro optical effects as alternatives to twisted nematic field effect LCDs (TN- and STN- LCDs). One approach was to use interdigital electrodes on one glass substrate only to produce an electric field essentially parallel to the glass substrates.Germany by Guenter Baur et al. and patented in various countries.Hitachi work out various practical details of the IPS technology to interconnect the thin-film transistor array as a matrix and to avoid undesirable stray fields in between pixels.
Hitachi also improved the viewing angle dependence further by optimizing the shape of the electrodes (Super IPS). NEC and Hitachi become early manufacturers of active-matrix addressed LCDs based on the IPS technology. This is a milestone for implementing large-screen LCDs having acceptable visual performance for flat-panel computer monitors and television screens. In 1996, Samsung developed the optical patterning technique that enables multi-domain LCD. Multi-domain and In Plane Switching subsequently remain the dominant LCD designs through 2006.South Korea and Taiwan,
In 2007 the image quality of LCD televisions surpassed the image quality of cathode-ray-tube-based (CRT) TVs.LCD TVs were projected to account 50% of the 200 million TVs to be shipped globally in 2006, according to Displaybank.Toshiba announced 2560 × 1600 pixels on a 6.1-inch (155 mm) LCD panel, suitable for use in a tablet computer,
In 2016, Panasonic developed IPS LCDs with a contrast ratio of 1,000,000:1, rivaling OLEDs. This technology was later put into mass production as dual layer, dual panel or LMCL (Light Modulating Cell Layer) LCDs. The technology uses 2 liquid crystal layers instead of one, and may be used along with a mini-LED backlight and quantum dot sheets.
Since LCDs produce no light of their own, they require external light to produce a visible image.backlight. Active-matrix LCDs are almost always backlit.Transflective LCDs combine the features of a backlit transmissive display and a reflective display.
CCFL: The LCD panel is lit either by two cold cathode fluorescent lamps placed at opposite edges of the display or an array of parallel CCFLs behind larger displays. A diffuser (made of PMMA acrylic plastic, also known as a wave or light guide/guiding plateinverter to convert whatever DC voltage the device uses (usually 5 or 12 V) to ≈1000 V needed to light a CCFL.
EL-WLED: The LCD panel is lit by a row of white LEDs placed at one or more edges of the screen. A light diffuser (light guide plate, LGP) is then used to spread the light evenly across the whole display, similarly to edge-lit CCFL LCD backlights. The diffuser is made out of either PMMA plastic or special glass, PMMA is used in most cases because it is rugged, while special glass is used when the thickness of the LCD is of primary concern, because it doesn"t expand as much when heated or exposed to moisture, which allows LCDs to be just 5mm thick. Quantum dots may be placed on top of the diffuser as a quantum dot enhancement film (QDEF, in which case they need a layer to be protected from heat and humidity) or on the color filter of the LCD, replacing the resists that are normally used.
WLED array: The LCD panel is lit by a full array of white LEDs placed behind a diffuser behind the panel. LCDs that use this implementation will usually have the ability to dim or completely turn off the LEDs in the dark areas of the image being displayed, effectively increasing the contrast ratio of the display. The precision with which this can be done will depend on the number of dimming zones of the display. The more dimming zones, the more precise the dimming, with less obvious blooming artifacts which are visible as dark grey patches surrounded by the unlit areas of the LCD. As of 2012, this design gets most of its use from upscale, larger-screen LCD televisions.
RGB-LED array: Similar to the WLED array, except the panel is lit by a full array of RGB LEDs. While displays lit with white LEDs usually have a poorer color gamut than CCFL lit displays, panels lit with RGB LEDs have very wide color gamuts. This implementation is most popular on professional graphics editing LCDs. As of 2012, LCDs in this category usually cost more than $1000. As of 2016 the cost of this category has drastically reduced and such LCD televisions obtained same price levels as the former 28" (71 cm) CRT based categories.
Monochrome LEDs: such as red, green, yellow or blue LEDs are used in the small passive monochrome LCDs typically used in clocks, watches and small appliances.
Today, most LCD screens are being designed with an LED backlight instead of the traditional CCFL backlight, while that backlight is dynamically controlled with the video information (dynamic backlight control). The combination with the dynamic backlight control, invented by Philips researchers Douglas Stanton, Martinus Stroomer and Adrianus de Vaan, simultaneously increases the dynamic range of the display system (also marketed as HDR, high dynamic range television or FLAD, full-area local area dimming).
The LCD backlight systems are made highly efficient by applying optical films such as prismatic structure (prism sheet) 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),
A pink elastomeric connector mating an LCD panel to circuit board traces, shown next to a centimeter-scale ruler. The conductive and insulating layers in the black stripe are very small.
A standard television receiver screen, a modern LCD panel, has over six million pixels, and they are all individually powered by a wire network embedded in the screen. The fine wires, or pathways, form a grid with vertical wires across the whole screen on one side of the screen and horizontal wires across the whole screen on the other side of the screen. To this grid each pixel has a positive connection on one side and a negative connection on the other side. So the total amount of wires needed for a 1080p display is 3 x 1920 going vertically and 1080 going horizontally for a total of 6840 wires horizontally and vertically. That"s three for red, green and blue and 1920 columns of pixels for each color for a total of 5760 wires going vertically and 1080 rows of wires going horizontally. For a panel that is 28.8 inches (73 centimeters) wide, that means a wire density of 200 wires per inch along the horizontal edge.
The LCD panel is powered by LCD drivers that are carefully matched up with the edge of the LCD panel at the factory level. The drivers may be installed using several methods, the most common of which are COG (Chip-On-Glass) and TAB (Tape-automated bonding) These same principles apply also for smartphone screens that are much smaller than TV screens.anisotropic conductive film or, for lower densities, elastomeric connectors.
Monochrome and later color passive-matrix LCDs were standard in most early laptops (although a few used plasma displaysGame Boyactive-matrix became standard on all laptops. The commercially unsuccessful Macintosh Portable (released in 1989) was one of the first to use an active-matrix display (though still monochrome). Passive-matrix LCDs are still used in the 2010s for applications less demanding than laptop computers and TVs, such as inexpensive calculators. In particular, these are used on portable devices where less information content needs to be displayed, lowest power consumption (no backlight) and low cost are desired or readability in direct sunlight is needed.
STN LCDs have to be continuously refreshed by alternating pulsed voltages of one polarity during one frame and pulses of opposite polarity during the next frame. Individual pixels are addressed by the corresponding row and column circuits. This type of display is called response times and poor contrast are typical of passive-matrix addressed LCDs with too many pixels and driven according to the "Alt & Pleshko" drive scheme. Welzen and de Vaan also invented a non RMS drive scheme enabling to drive STN displays with video rates and enabling to show smooth moving video images on an STN display.
Bistable LCDs do not require continuous refreshing. Rewriting is only required for picture information changes. In 1984 HA van Sprang and AJSM de Vaan invented an STN type display that could be operated in a bistable mode, enabling extremely high resolution images up to 4000 lines or more using only low voltages.
High-resolution color displays, such as modern LCD computer monitors and televisions, use an active-matrix structure. A matrix of thin-film transistors (TFTs) is added to the electrodes in contact with the LC layer. Each pixel has its own dedicated transistor, allowing each column line to access one pixel. When a row line is selected, all of the column lines are connected to a row of pixels and voltages corresponding to the picture information are driven onto all of the column lines. The row line is then deactivated and the next row line is selected. All of the row lines are selected in sequence during a refresh operation. Active-matrix addressed displays look brighter and sharper than passive-matrix addressed displays of the same size, and generally have quicker response times, producing much better images. Sharp produces bistable reflective LCDs with a 1-bit SRAM cell per pixel that only requires small amounts of power to maintain an image.
Segment LCDs can also have color by using Field Sequential Color (FSC LCD). This kind of displays have a high speed passive segment LCD panel with an RGB backlight. The backlight quickly changes color, making it appear white to the naked eye. The LCD panel is synchronized with the backlight. For example, to make a segment appear red, the segment is only turned ON when the backlight is red, and to make a segment appear magenta, the segment is turned ON when the backlight is blue, and it continues to be ON while the backlight becomes red, and it turns OFF when the backlight becomes green. To make a segment appear black, the segment is always turned ON. An FSC LCD divides a color image into 3 images (one Red, one Green and one Blue) and it displays them in order. Due to persistence of vision, the 3 monochromatic images appear as one color image. An FSC LCD needs an LCD panel with a refresh rate of 180 Hz, and the response time is reduced to just 5 milliseconds when compared with normal STN LCD panels which have a response time of 16 milliseconds.
Samsung introduced UFB (Ultra Fine & Bright) displays back in 2002, utilized the super-birefringent effect. It has the luminance, color gamut, and most of the contrast of a TFT-LCD, but only consumes as much power as an STN display, according to Samsung. It was being used in a variety of Samsung cellular-telephone models produced until late 2006, when Samsung stopped producing UFB displays. UFB displays were also used in certain models of LG mobile phones.
In-plane switching is an LCD technology that aligns the liquid crystals in a plane parallel to the glass substrates. In this method, the electrical field is applied through opposite electrodes on the same glass substrate, so that the liquid crystals can be reoriented (switched) essentially in the same plane, although fringe fields inhibit a homogeneous reorientation. This requires two transistors for each pixel instead of the single transistor needed for a standard thin-film transistor (TFT) display. The IPS technology is used in everything from televisions, computer monitors, and even wearable devices, especially almost all LCD smartphone panels are IPS/FFS mode. IPS displays belong to the LCD panel family screen types. The other two types are VA and TN. Before LG Enhanced IPS was introduced in 2001 by Hitachi as 17" monitor in Market, the additional transistors resulted in blocking more transmission area, thus requiring a brighter backlight and consuming more power, making this type of display less desirable for notebook computers. Panasonic Himeji G8.5 was using an enhanced version of IPS, also LGD in Korea, then currently the world biggest LCD panel manufacture BOE in China is also IPS/FFS mode TV panel.
In 2015 LG Display announced the implementation of a new technology called M+ which is the addition of white subpixel along with the regular RGB dots in their IPS panel technology.
Most of the new M+ technology was employed on 4K TV sets which led to a controversy after tests showed that the addition of a white sub pixel replacing the traditional RGB structure would reduce the resolution by around 25%. This means that a 4K TV cannot display the full UHD TV standard. The media and internet users later called this "RGBW" TVs because of the white sub pixel. Although LG Display has developed this technology for use in notebook display, outdoor and smartphones, it became more popular in the TV market because the announced 4K UHD resolution but still being incapable of achieving true UHD resolution defined by the CTA as 3840x2160 active pixels with 8-bit color. This negatively impacts the rendering of text, making it a bit fuzzier, which is especially noticeable when a TV is used as a PC monitor.
In 2011, LG claimed the smartphone LG Optimus Black (IPS LCD (LCD NOVA)) has the brightness up to 700 nits, while the competitor has only IPS LCD with 518 nits and double an active-matrix OLED (AMOLED) display with 305 nits. LG also claimed the NOVA display to be 50 percent more efficient than regular LCDs and to consume only 50 percent of the power of AMOLED displays when producing white on screen.
This pixel-layout is found in S-IPS LCDs. A chevron shape is used to widen the viewing cone (range of viewing directions with good contrast and low color shift).
Vertical-alignment displays are a form of LCDs in which the liquid crystals naturally align vertically to the glass substrates. When no voltage is applied, the liquid crystals remain perpendicular to the substrate, creating a black display between crossed polarizers. When voltage is applied, the liquid crystals shift to a tilted position, allowing light to pass through and create a gray-scale display depending on the amount of tilt generated by the electric field. It has a deeper-black background, a higher contrast ratio, a wider viewing angle, and better image quality at extreme temperatures than traditional twisted-nematic displays.
Blue phase mode LCDs have been shown as engineering samples early in 2008, but they are not in mass-production. The physics of blue phase mode LCDs suggest that very short switching times (≈1 ms) can be achieved, so time sequential color control can possibly be realized and expensive color filters would be obsolete.
Some LCD panels have defective transistors, causing permanently lit or unlit pixels which are commonly referred to as stuck pixels or dead pixels respectively. Unlike integrated circuits (ICs), LCD panels with a few defective transistors are usually still usable. Manufacturers" policies for the acceptable number of defective pixels vary greatly. At one point, Samsung held a zero-tolerance policy for LCD monitors sold in Korea.ISO 13406-2 standard.
Dead pixel policies are often hotly debated between manufacturers and customers. To regulate the acceptability of defects and to protect the end user, ISO released the ISO 13406-2 standard,ISO 9241, specifically ISO-9241-302, 303, 305, 307:2008 pixel defects. However, not every LCD manufacturer conforms to the ISO standard and the ISO standard is quite often interpreted in different ways. LCD panels are more likely to have defects than most ICs due to their larger size. For example, a 300 mm SVGA LCD has 8 defects and a 150 mm wafer has only 3 defects. However, 134 of the 137 dies on the wafer will be acceptable, whereas rejection of the whole LCD panel would be a 0% yield. In recent years, quality control has been improved. An SVGA LCD panel with 4 defective pixels is usually considered defective and customers can request an exchange for a new one.
Some manufacturers, notably in South Korea where some of the largest LCD panel manufacturers, such as LG, are located, now have a zero-defective-pixel guarantee, which is an extra screening process which can then determine "A"- and "B"-grade panels.clouding (or less commonly mura), which describes the uneven patches of changes in luminance. It is most visible in dark or black areas of displayed scenes.
The zenithal bistable device (ZBD), developed by Qinetiq (formerly DERA), can retain an image without power. The crystals may exist in one of two stable orientations ("black" and "white") and power is only required to change the image. ZBD Displays is a spin-off company from QinetiQ who manufactured both grayscale and color ZBD devices. Kent Displays has also developed a "no-power" display that uses polymer stabilized cholesteric liquid crystal (ChLCD). In 2009 Kent demonstrated the use of a ChLCD to cover the entire surface of a mobile phone, allowing it to change colors, and keep that color even when power is removed.
In 2004, researchers at the University of Oxford demonstrated two new types of zero-power bistable LCDs based on Zenithal bistable techniques.e.g., BiNem technology, are based mainly on the surface properties and need specific weak anchoring materials.
Resolution The resolution of an LCD is expressed by the number of columns and rows of pixels (e.g., 1024×768). Each pixel is usually composed 3 sub-pixels, a red, a green, and a blue one. This had been one of the few features of LCD performance that remained uniform among different designs. However, there are newer designs that share sub-pixels among pixels and add Quattron which attempt to efficiently increase the perceived resolution of a display without increasing the actual resolution, to mixed results.
Spatial performance: For a computer monitor or some other display that is being viewed from a very close distance, resolution is often expressed in terms of dot pitch or pixels per inch, which is consistent with the printing industry. Display density varies per application, with televisions generally having a low density for long-distance viewing and portable devices having a high density for close-range detail. The Viewing Angle of an LCD may be important depending on the display and its usage, the limitations of certain display technologies mean the display only displays accurately at certain angles.
Temporal performance: the temporal resolution of an LCD is how well it can display changing images, or the accuracy and the number of times per second the display draws the data it is being given. LCD pixels do not flash on/off between frames, so LCD monitors exhibit no refresh-induced flicker no matter how low the refresh rate.
Color performance: There are multiple terms to describe different aspects of color performance of a display. Color gamut is the range of colors that can be displayed, and color depth, which is the fineness with which the color range is divided. Color gamut is a relatively straight forward feature, but it is rarely discussed in marketing materials except at the professional level. Having a color range that exceeds the content being shown on the screen has no benefits, so displays are only made to perform within or below the range of a certain specification.white point and gamma correction, which describe what color white is and how the other colors are displayed relative to white.
Brightness and contrast ratio: Contrast ratio is the ratio of the brightness of a full-on pixel to a full-off pixel. The LCD itself is only a light valve and does not generate light; the light comes from a backlight that is either fluorescent or a set of LEDs. Brightness is usually stated as the maximum light output of the LCD, which can vary greatly based on the transparency of the LCD and the brightness of the backlight. Brighter backlight allows stronger contrast and higher dynamic range (HDR displays are graded in peak luminance), but there is always a trade-off between brightness and power consumption.
Usually no refresh-rate flicker, because the LCD pixels hold their state between refreshes (which are usually done at 200 Hz or faster, regardless of the input refresh rate).
No theoretical resolution limit. When multiple LCD panels are used together to create a single canvas, each additional panel increases the total resolution of the display, which is commonly called stacked resolution.
LCDs can be made transparent and flexible, but they cannot emit light without a backlight like OLED and microLED, which are other technologies that can also be made flexible and transparent.
As an inherently digital device, the LCD can natively display digital data from a DVI or HDMI connection without requiring conversion to analog. Some LCD panels have native fiber optic inputs in addition to DVI and HDMI.
Limited viewing angle in some older or cheaper monitors, causing color, saturation, contrast and brightness to vary with user position, even within the intended viewing angle. Special films can be used to increase the viewing angles of LCDs.
Display motion blur on moving objects caused by slow response times (>8 ms) and eye-tracking on a sample-and-hold display, unless a strobing backlight is used. However, this strobing can cause eye strain, as is noted next:
As of 2012, most implementations of LCD backlighting use pulse-width modulatio