lcd panel contrast ratio quotation

Contrast ratio should be black and white. Taken at face value, it"s the ratio of the light level (luminance) the display produces when fed a white signal to the luminance when it"s fed a black signal. Unfortunately, it"s probably the most misused, inflated, and ultimately misleading specification used to describe HDTVs today.

At the 2009 Consumer Electronics Show, manufacturers quoted contrast ratio specs of 1,000,000:1 or 2,000,000:1 for upcoming Samsung and Sony for their current LED models. Those numbers sure do sound impressive, but what do they mean in the real world?

Very little. It"s true that in general, a higher contrast ratio can indicate that the display produces a deeper level of black, with all of the picture-quality benefits that brings--but then again it might not. Despite the million-to-one contrast ratios of the Samsung and Sony LED sets we reviewed, we observed better black-level performance in the Pioneer PRO-111FD. Pioneer doesn"t publish a contrast ratio spec for that television, but has claimed that its black levels are so deep as to be "immeasurable."

Manufacturers are free to use whatever method they like to "measure" the contrast ratio of their displays. The big numbers you see quoted most often are for "dynamic" contrast ratio, which takes into account changes the (usually LCD) display makes to adjust for fluctuations in the brightness of the content--namely, lowering the backlight in dark scenes and bringing it up in lighter ones. Then there"s the "native" contrast ratio number, always much smaller than the dynamic one, where the display doesn"t perform these adjustments. Both of these numbers are usually derived from the measurement of a full-white screen and a full-black screen (so-called full-on, full-off measurements), which is obviously not representative of actual program material.

A more-representative method is the ANSI contrast ratio measurement, which uses a checkerboard of eight white and eight black squares; the average luminance of the white and black squares determines the contrast ratio. Unfortunately, you"ll almost never see any manufacturer quote an ANSI number, since it"s usually tiny in comparison--a few hundred or few thousand or so to one.

We have seen some signs of millions-fatigue in the CR spec game, however. At CES 2009, Samsung"s press material didn"t publish a number, instead using the phrase "mega-contrast" without any accompanying number. LG and Vizio use the same phrase, but did publish the numbers. We"ve already mentioned how Pioneer is avoiding numbers, and we hope more TV makers follow suit. When the numbers can be so inflated or simply made up, what"s the point?

That"s why we hope you"ll pay as little attention to published contrast ratio specs as we do. We rarely mention them in reviews, and when we have to refer to them in news or blog posts we try to put them in context, comparing last year"s specs from the same manufacturer with this year"s, for example. We"re still working on performing contrast ratio measurements ourselves as part of TV reviews, so look for that to happen this year. When it does, we doubt we"ll publish anything close to "one million."

The contrast ratio (CR) is a property of a display system, defined as the ratio of the luminance of the brightest shade (white) to that of the darkest shade (black) that the system is capable of producing. A high contrast ratio is a desired aspect of any display. It has similarities with dynamic range.

There is no official, standardized way to measure contrast ratio for a system or its parts, nor is there a standard for defining "Contrast Ratio" that is accepted by any standards organization so ratings provided by different manufacturers of display devices are not necessarily comparable to each other due to differences in method of measurement, operation, and unstated variables.projection screen or emitted by a cathode ray tube, and the only light seen in the room would come from the display device. With such a room, the contrast ratio of the image would be the same as the contrast ratio of the device. Real rooms reflect some of the light back to the displayed image, lowering the contrast ratio seen in the image.

Static contrast ratio is the luminosity ratio comparing the brightest and darkest shade the system is capable of producing simultaneously at any instant of time, while dynamic contrast ratio is the luminosity ratio comparing the brightest and darkest shade the system is capable of producing over time (while the picture is moving). Moving from a system that displays a static motionless image to a system that displays a dynamic, changing picture slightly complicates the definition of the contrast ratio, due to the need to take into account the extra temporal dimension to the measuring process.

Many display devices favor the use of the full on/full off method of measurement, as it cancels out the effect of the room and results in an ideal ratio. Equal proportions of light reflect from the display to the room and back in both "black" and "white" measurements, as long as the room stays the same. This will inflate the light levels of both measurements proportionally, leaving the black to white luminance ratio unaffected.

Some manufacturers have gone as far as using different device parameters for the three tests, even further inflating the calculated contrast ratio. With DLP projectors, one method to do this is to enable the clear sector of the color filter wheel for the "on" part and disable it for the "off" part

Another measure is the ANSI contrast, in which the measurement is done with a checker board patterned test image where the black and white luminosity values are measured simultaneously.

It is useful to note that the full on/full off method effectively measures the dynamic contrast ratio of a display, while the ANSI contrast measures the static contrast ratio.

An LCD technology is dynamic contrast (DC), also called advanced contrast ratio (ACR) and various other designations. When there is a need to display a dark image, a display that supports dynamic contrast underpowers the backlight lamp (or decreases the aperture of the projector"s lens using an iris), but proportionately amplifies the transmission through the LCD panel; this gives the benefit of realizing the potential static contrast ratio of the LCD panel in dark scenes when the image is watched in a dark room. The drawback is that if a dark scene contains small areas of superbright light, the resulting image will be over exposed.

It is also common to market only the dynamic contrast ratio capability of a display (when it is better than its static contrast ratio only on paper), which should not be directly compared to the static contrast ratio. A plasma display with a 4,000,000:1 static contrast ratio will show superior contrast to an LCD (with LED or CCFL backlight) with 30,000,000:1 dynamic and 20,000:1 static contrast ratio when the input signal contains a full range of brightnesses from 0 to 100% simultaneously. They will, however, be on par when input signal ranges only from 0 to 20% brightness.

This animated gif shows a rudimentary representation of how various backlight dimming technologies work on TV. Dimming technology can drastically affect the contrast ratio of the display.

In marketing literature, contrast ratios for emissive (as opposed to reflective) displays are always measured under the optimum condition of a room in total darkness. In typical viewing situations, the contrast ratio is significantly lower due to the reflection of light from the surface of the display, making it harder to distinguish between different devices with very high contrast ratios.luminance of the display, as well as the amount of light reflecting off the display.

The contrast ratio is a measure of the difference in luminance between the light and dark elements of a display. It’s important to consider when choosing which display technology to use, as it can significantly affect the user experience. A higher contrast ratio generally means that the display will appear brighter, sharper, and more vivid than a display with a lower contrast ratio.

The contrast ratio is a measure of the difference in luminance between the light and dark elements of a display. It’s important to consider when choosing which display technology to use, as it can significantly affect the user experience. A higher contrast ratio generally means that the display will appear brighter, sharper, and more vivid than a display with a lower contrast ratio.

The contrast ratio of a display is typically measured by comparing the luminance of the brightest white on the display to the darkest black. The higher the contrast ratio, the greater the range of luminance the display can reproduce. For example, a display with a contrast ratio of 1000:1 can reproduce 1000 times as much luminance in the brightest white as in the darkest black.

In addition to affecting a display’s overall brightness and sharpness, contrast ratio is also an important factor in the legibility of text and other fine details. Displays with a higher contrast ratio tend to be better at reproducing fine details, making them more suitable for applications like reading text or viewing high-resolution images.

It’s important to note that the contrast ratio is only a measure of the relative luminance of the display, not the absolute luminance. This means that two displays with the same contrast ratio may appear differently depending on their overall luminance. In other words, a display with a higher contrast ratio may not necessarily be brighter than a display with a lower contrast ratio.

When choosing a display, it’s important to consider the contrast ratio along with other factors like resolution, refresh rate, and viewing angle. A high-contrast display may not be the best choice for all applications, and it’s important to choose the right display technology for your specific needs.

Static contrast ratio is the most common method of measuring contrast ratio and is typically what is quoted by manufacturers. It is calculated by measuring the luminance of the brightest white and the darkest black that a display can produce and then dividing the former by the latter. For example, a display with a static contrast ratio of 1000:1 can produce 1000 times as much luminance in the brightest white as it can in the darkest black.

Dynamic contrast ratio, on the other hand, is a measure of the ratio between the brightest and darkest colors that a display can produce at any given moment. This means that it takes into account not just the maximum luminance of the display but also the way that the display is able to adjust its luminance in real-time to match the content being displayed.

Dynamic contrast ratio is typically higher than static contrast ratio, as it allows for greater flexibility in the way that the display can adjust its luminance. However, it is also more difficult to measure accurately, and as such, is not as commonly quoted by manufacturers.

Overall, the contrast ratio is an important factor to consider when choosing a display, as it can significantly affect the user experience. Higher contrast ratios generally result in brighter, sharper, and more vivid displays, but it’s important to consider other factors like resolution, refresh rate, and viewing angle as well.

First, it’s important to understand that the contrast ratio is only a measure of the relative luminance of the display, not the absolute luminance. This means that two displays with the same contrast ratio may appear differently depending on their overall luminance. In other words, a display with a higher contrast ratio may not necessarily be brighter than a display with a lower contrast ratio.

Second, there are two common methods of measuring contrast ratio: static and dynamic. Static contrast ratio is the ratio of the brightest color (white) to the darkest color (black) that a display can produce, while dynamic contrast ratio is a measure of the ratio between the brightest and darkest colors that a display can produce at any given moment. Dynamic contrast ratio is typically higher than static contrast ratio, but it is also more difficult to measure accurately.

Third, it’s important to consider the viewing environment when choosing a display based on contrast ratio. In a brightly lit room, for example, a display with a high contrast ratio may be less effective than a display with a lower contrast ratio, as the ambient light can wash out the image on the screen. In a dimly lit room, on the other hand, a high contrast ratio can be beneficial, as it allows the display to produce deeper blacks and brighter whites.

In conclusion, the contrast ratio is an important factor to consider when choosing a display, but it’s not the only factor. It’s important to consider the viewing environment, the type of content being displayed, and the other technical specifications of the display as well in order to choose the right display technology for your needs.

In a brightly lit room, a display with a high contrast ratio may not be as effective as a display with a lower contrast ratio. This is because the ambient light can wash out the image on the screen, reducing the overall contrast and making it difficult to see the details in the darkest and lightest parts of the image. In this situation, a display with a lower contrast ratio may be more suitable, as it will be able to reproduce a wider range of luminance levels without being overpowered by the ambient light.

On the other hand, in a dimly lit room, a high contrast ratio can be beneficial. This is because the display will be able to produce deeper blacks and brighter whites, creating a more vivid and immersive image. In this situation, a display with a high contrast ratio may be the better choice, as it will be able to make the most of the available light and provide a more engaging viewing experience.

Overall, it’s important to consider the ambient lighting conditions when choosing a display based on contrast ratio. In a brightly lit room, a display with a lower contrast ratio may be more suitable, while in a dimly lit room, a display with a higher contrast ratio may be more effective.

The viewing angle of a display refers to the angle at which the image on the screen remains visible and clear. As the viewing angle increases, the contrast ratio of the display decreases, as the image on the screen becomes less defined and less distinct. This can make it more difficult to see the details in the darkest and lightest parts of the image, reducing the overall sharpness and vividness of the display.

For this reason, it’s important to consider the viewing angle when selecting a display based on the contrast ratio. A display with a narrow viewing angle may have a higher contrast ratio, but it may not be suitable for applications that require a wider viewing angle. In this situation, a display with a lower contrast ratio but a wider viewing angle may be a better choice.

Overall, the viewing angle of a display is an important factor to consider when selecting a display based on contrast ratio. A display with a wide viewing angle may not have as high a contrast ratio, but it may be more suitable for certain applications. It’s important to consider the specific needs of your application when choosing the right display technology.

OLED and quantum dot are advanced display technologies that can significantly improve the contrast ratio of a display. OLED (organic light-emitting diode) displays use organic compounds that emit light when an electric current is applied to them. These displays can produce a wide range of colors, including very bright and vivid ones, and they have a high contrast ratio due to their ability to produce deep blacks.

Quantum dot displays, on the other hand, use tiny particles of light-emitting material called quantum dots. These particles are extremely small, measuring just a few nanometers in diameter, and they are capable of emitting very bright and vibrant colors. Quantum dot displays have an even higher contrast ratio than OLED displays, as the quantum dots can produce an even wider range of colors and luminance levels.

Overall, OLED and quantum dot are advanced display technologies that can significantly improve the contrast ratio of a display. They are able to produce brighter and more vivid colors, and they can provide a more immersive and engaging viewing experience. These technologies are commonly used in high-end TVs and other displays, and they are an important factor to consider when choosing the right display technology for your needs.

High dynamic range (HDR) and contrast ratio are two important factors to consider when choosing a display technology. HDR is a display technology that provides a wider range of luminance levels and a higher contrast ratio, allowing for the reproduction of a greater range of colors and more detailed and realistic images. Contrast ratio, on the other hand, is a measure of the difference in luminance between the light and dark elements of a display.

HDR and contrast ratio are closely related, as HDR relies on a high contrast ratio to produce its enhanced visual effects. A display with a higher contrast ratio is able to reproduce a wider range of luminance levels, resulting in brighter whites, deeper blacks, and more vivid colors. This allows HDR displays to produce images that are more detailed and realistic, with greater contrast and more accurate color reproduction.

There are several different technologies and standards used in HDR displays, including OLED, quantum dot, and various proprietary technologies. These technologies use different methods to achieve a high contrast ratio, but they all have the same goal of producing more detailed and realistic images.

Overall, HDR and contrast ratio are important factors to consider when choosing a display technology. HDR relies on a high contrast ratio to produce its enhanced visual effects, and choosing the right technology and standard can help ensure that you get the best possible performance from your HDR display.

The contrast ratio is an important factor to consider when choosing a display. Higher contrast ratios generally result in brighter, sharper, and more vivid displays, but it’s important to consider other factors like resolution, refresh rate, and viewing angle as well. Advanced display technologies like OLED and quantum dot can improve the contrast ratio of a display, but it’s important to choose the right technology for your specific needs.

There was a time when I used to lambast the meaninglessness of dynamic contrast ratio figures quoted in the latest TVs and monitors, but now I just give up...

Samsung has launched the "XL2370", a 23in 16:9 LED backlit monitor which it claims has a 5,000,000:1 dynamic contrast ratio. Let me say that again: 5,000,000:1. To put this in perspective, the eighth generation Pioneer Kuro - a set which revolutionised the HDTV landscape (as is still only bettered by its successor) - has a 16,000:1 contrast ratio. Sigh.

Cockpit instrumentation in the aerospace industry has evolved over the past decades. In the past, control panels had backlit gauges, switches, and knobs, where now you are more likely to see an array of flat panel screens. There must be a consistent light and color emitting from these panels to reduce eyestrain, ease interpretation of data, and decrease distractions. In addition, they are comfortable to view equally in daylight and as well as night. Two key measurements are Luminance (a measure of brightness) and Display Contrast (the ratio between light and dark).

Display Contrast is the ratio between the brightest colors (in most cases white) and the darkest color (in most cases black) that the monitor is capable of producing. Where there is no industry standard in measuring contrast the generally accepted process is to measure parts of a screen and either take the average or highest white and the average or lowest black and express it in ratio form bright:dark. As an example, if a screen has bright luminance of 150 nits and a dark luminance of 1 nit the contrast ratio would be shown as 150:1.

With newer high performance, OLEDs with darker blacks are now producing much wider ratios. Hence, if a monitor can output 7500 nits with a white screen and 0.010 nits with a black screen, it would have a contrast ratio of 750,000:1. A higher contrast produces more in-depth images with better screen quality, giving richer colors that make it easier to interpret images and data. A decent LCD screen might have a contrast ratio of 1,000:1. The contrast on an OLED display is far higher, at around 4000:1, with ultra-high-end units beginning to get close to 1,000,000:1. When an OLED screen shows black, its pixels produce almost no light whatsoever.

A display’s contrast ratio is one of the most important measurements of performance. In addition, it will be the most noticeable difference between two displays in a side-by-side comparison.

To measure contrast it is best to use a spectroradiometer such as the CS-2000 and CS-2000A. With high-end spectroradiometers, you can measure the darkest blacks down to super-low luminance of 0.003cd/m2 allowing measurements up to 1,000,000:1.

The answers to these questions are significantly lower than in the brochure or spec sheet because the number we actually need is the so-called ANSI contrast ratio, whereas the specification sheet uses the so-called sequential method, where white and black levels are measured at different times and in idealised measurement conditions. It measures something that cannot be seen by the human eye. The only question it answers is ‘what is the maximum theoretical contrast number I could measure, even if I can’t see it myself and even if it’s measured in a light absorbing black cave’?

Back in the real world, most display types can deliver good or even outstanding viewing experiences, whether flat panel display, projected displays or direct view LED etc. But, without exception, you’re always specifying a system - even if you just get a flat panel display out of its box and hang it on a wall. It’s because all displays look and perform measurably different, depending on the lighting scenarios you view them in. Every screen of every type you ever supply is always a system and these systems includes the lighting conditions under which it’s viewed.

In the case of flat panel display display screens, their reflectivity, coupled with direct lighting sources can create terrible viewing experiences for some viewers in a room when the next person’s experience can be just fine.

Several manufacturers have introduced dynamic contrast controls to their monitors which are designed to improve black and white levels and contrast of the display on the fly, in certain conditions. It is supposed to help colours look more vivid and bright, text look sharper and enhance the extremes ends of the colour scale, making blacks deeper and whites brighter. This is achieved by adjusting the brightness of the backlighting rather than any adjustments at the matrix / panel level. The backlighting can be made less intensive in dark scenes, to make them even darker, and more intensive, up to the maximum, in bright scenes, to make them even brighter.

The official numbers for dynamic contrast are arrived at in the following manner: the level of white is measured at the maximum of backlight brightness and the level of black is measured at its minimum. So if the matrix has a specified contrast ratio of 1000:1 and the monitor’s electronics can automatically change the intensity of backlight brightness by 300%, the resulting dynamic contrast is 3000:1. Of course, the screen contrast – the ratio of white to black – is never higher than the monitor’s static specified contrast ratio at any given moment, but the level of black is not important for the eye in bright scenes and vice versa. That’s why the automatic brightness adjustment in movies is indeed helpful and creates an impression of a monitor with a greatly enhanced dynamic range.

The downside is that the brightness of the whole screen is changed at once. In scenes that contain both light and dark objects in equal measure, the monitor will just select some average brightness. Dynamic contrast doesn’t work well on dark scenes with a few small, but very bright objects (like a night street with lamp-posts) – the background is dark, and the monitor will lower brightness to a minimum, dimming the bright objects as a consequence. Ideally this kind of enhancement shouldn"t be used in office work since it can prove distracting or problematic for colour work. However, movies and sometimes gaming can offer some impressive improvements thanks to such technologies.

Unlike CRT monitors, LCD monitors display information well at only the resolution they are designed for, which is known as the native resolution. Digital displays address each individual pixel using a fixed matrix of horizontal and vertical dots. If you change the resolution settings, the LCD scales the image and the quality suffers. Native resolutions are typically:

When you look at an LCD monitor from an angle, the image can look dimmer or even disappear. Colors can also be misrepresented. To compensate for this problem, LCD monitor makers have designed wider viewing angles. (Do not confuse this with a widescreen display, which means the display is physically wider.) Manufacturers give a measure of viewing angle in degrees (a greater number of degrees is better). In general, look for between 120 and 170 degrees. Because manufacturers measure viewing angles differently, the best way to evaluate it is to test the display yourself. Check the angle from the top and bottom as well as the sides, bearing in mind how you will typically use the display.

This is a measurement of the amount of light the LCD monitor produces. It is given in nits or one candelas per square meter (cd/m2). One nit is equal to one cd/m2. Typical brightness ratings range from 250 to 350 cd/m2 for monitors that perform general-purpose tasks. For displaying movies, a brighter luminance rating such as 500 cd/m2 is desirable.

The contrast ratio rates the degree of difference of an LCD monitor"s ability to produce bright whites and the dark blacks. The figure is usually expressed as a ratio, for example, 500:1. Typically, contrast ratios range from 450:1 to 600:1, and they can be rated as high as 1000:1. Ratios more than 600:1, however, provide little improvement over lower ratios.

Unlike CRT monitors, LCD monitors have much more flexibility for positioning the screen the way you want it. LCD monitors can swivel, tilt up and down, and even rotate from landscape (with the horizontal plane longer than the vertical plane) to portrait mode (with the vertical plane longer than the horizontal plane). In addition, because they are lightweight and thin, most LCD monitors have built-in brackets for wall or arm mounting.

Besides the basic features, some LCD monitors have other conveniences such as integrated speakers, built-in Universal Serial Bus (USB) ports and anti-theft locks.

Contrast ratio - The difference in light intensity between white and black on an LCD display is called contrast ratio. The higher the contrast ratio, the easier it is to see details.

Ghosting - An effect of slower response times that cause blurring of images on an LCD monitor, it"s also known as latency. The effect is caused by voltage temporarily leaking from energized elements to neighboring, non-energized elements on the display.

Luminance - Also known as brightness, it is the level of light emitted by an LCD display. Luminance is measured in nits or candelas per square meter (cd/m2). One nit is equal to one cd/m2.

Stuck pixels - A pixel that is stuck either "on" or "off", meaning that it is always illuminated, unlit, or stuck on one color regardless of the image the LCD monitor displays can also be called a dead pixel.

Again, IPS is the clear winner here. The vertical viewing angles are very similar to the horizontal ones on both IPS and VA panels. Unfortunately, this is one area where TN panels are usually much, much worse. TN monitors degrade rapidly from below, and colors actually inverse - resulting in a negative image that can be distracting. For this reason, if you decide to buy a TN monitor, look for one with an excellent height adjustment, or consider buying a VESA mounting arm, as you should mount TN monitors at eye level. Even when mounted properly, larger TN displays can appear non-uniform at the edges.

There"s usually not much difference between VA and IPS panels in terms of gray uniformity. It"s rare for monitors to have uniformity issues, and even on monitors that perform worse than average, it"s usually not noticeable with regular content. TN monitors tend to perform a bit worse than usual, though, and the top half of the screen is almost always darker than the rest, but that"s an artifact of the bad vertical viewing angles.

Black uniformity tends to vary significantly, even between individual units of the same model, and there"s no single panel type that performs the best. It"s rare for monitors to have good black uniformity, and almost every monitor we"ve tested has some noticeable cloudiness or backlight bleed. IPS and TN panels can look slightly worse due to their low contrast ratios, as the screen can take on more of a bluish tint when displaying dark scenes. Like with contrast, black uniformity issues usually aren"t very noticeable unless you"re looking at dark content and you"re in a dark room. If you only use your monitor in a bright environment, generally speaking, you don"t need to worry about black uniformity.

Historically, TN panels used to have the worst colors, as many of them were cheaper models that only supported 6-bit colors or used techniques like dithering (FRC) to approximate 8-bit colors. Most displays today, including TN models, are at least 8 bit, and many of them are even able to approximate 10-bit colors through dithering. New technologies, like LG"s Nano IPS and Samsung"s Quantum Dot, add an extra layer to the LCD stack and have significantly improved the color gamut of modern IPS and VA displays, leaving TN a bit behind. Between them, NANO IPS is slightly better, as it tends to offer better coverage of the Adobe RGB color space. Although the difference is minor, IPS panels still have a slight edge over VA and TN displays.

Although TN panels have caught up a bit in the SDR color space, they"re far behind when it comes to HDR, so if you"re looking for a good HDR color gamut, avoid TN panels. Between VA and IPS panels, the difference isn"t as significant; however, IPS panels still have a slight edge. The best VA panels top out at around 90% coverage of the DCI P3 color space used by most current HDR content. IPS panels go as high as 98% coverage of DCI P3, rivaling even some of the best TVs on the market. Due to the very high coverage of DCI P3 on both VA and IPS, the difference isn"t that noticeable, though, as most content won"t use the entire color space anyway.

Although not necessarily as noticeable to everyone as the differences in picture quality, there can also be a difference in motion handling between IPS, VA, and TN displays. TN panels historically offered the best gaming performance, as they had the highest refresh rates and extremely fast response times. Manufacturers have found ways to drastically improve the motion handling of VA and IPS panels, though, and the difference isn"t as pronounced.

LCD panel technology has changed drastically over the last few years, and the historical expectations for response time performance don"t necessarily hold anymore. For years, TN monitors had the fastest response times by far, but that"s started to change. New high refresh-rate IPS monitors can be just as fast.

VA panels are a bit of a strange situation. They typically have slightly slower response times overall compared to similar TN or IPS models. It"s especially noticeable in near-black scenes, where they tend to be significantly slower, resulting in dark trails behind fast-moving objects in dark scenes, commonly known as black smear. Some recent VA panels, such as the Samsung Odyssey G7 LC32G75T, get around it by overdriving the pixels. It results in much better dark scene performance but a more noticeable overshoot in brighter areas.

Within each of the three types of LCD we mentioned, other related panel types use the same basic idea but with slight differences. For example, two popular variants of IPS panels include ADS (technically known as ADSDS, or Advanced Super Dimension Switch) and PLS (Plane to Line Switching). It can be hard to tell these panels apart simply based on the subpixel structure, so we"ll usually group them all as IPS, and in the text, we"ll usually refer to them as IPS-like or IPS family. There are slight differences in colors, viewing angles, and contrast, but generally speaking, they"re all very similar.

There"s another display technology that"s growing in popularity: OLED. OLED, or organic light-emitting diode, is very different from the conventional LCD technology we"ve explored above. OLED panels are electro-emissive, which means each pixel emits its own light when it receives an electric signal, eliminating the need for a backlight. Since OLED panels can turn off individual pixels, they have deep, inky blacks with no blooming around bright objects. They also have excellent wide viewing angles, a near-instantaneous response time, and excellent gray uniformity.

OLED panels aren"t perfect, though. There"s a risk of permanent burn-in, especially when there are lots of static elements on screen, like the UI elements of a PC. There aren"t many OLED monitors available, either, but they"ve started to gain popularity as laptop screens and for high-end monitors, but they"re very expensive and hard to find. They"re also not very bright in some cases, especially when large bright areas are visible on screen. The technology is still maturing, and advances in OLED technology, like Samsung"s highly-anticipated QD-OLED technology, are promising.

As you can probably tell by now, no one panel type works best for everyone; it all depends on your exact usage. Although there used to be some significant differences between panel types, as technology has improved, these differences aren"t as noticeable. The two exceptions to this are viewing angles and contrast. If you"re in a dark room, a VA panel that can display deep blacks is probably the best choice. If you"re not in a dark room, you should focus on the other features of the monitor and choose based on the features that appeal to your exact usage. IPS panels are generally preferred for office use, and TN typically offers the best gaming experience, but recent advancements in VA and IPS technology are starting to change those generalizations. For the most part, the differences between each panel type are so minor now that it doesn"t need to be directly factored into your buying decision.

Now shipping with all the but the cheapest complete PCs are LCD monitors. Advances in display manufacturing and associated cost reductions with economies of scale have brought LCD monitors into the mainstream, shipping with budget systems that start at just £400. LCD monitors come in all shapes and sizes, have differing resolutions and inputs. The purpose of this HEXUS.help guide is to provide a basic understanding of how LCDs work, delineate their desirable characteristics, and to offer basic buying advice.

LCDs work in a relatively easy method to understand. Firstly, behind each LCD screen, where screens are defined by the number of pixels on a given panel, a light source is shone through from the behind to panel, through two panels of glass sandwiching the LCD, to your eyes. Each pixel on the LCD display has an array of liquid crystals (from whence the name arrives) whose molecules can be charged with a variable amount of voltage from electrodes over each subpixel (where each pixel is divided into red, blue and green filters), resulting in varying levels of light, from the source, passing through. Oversimplifying it somewhat, it"s the combination of subpixel voltage-switching and light source that make up the images you see.

LCD technology encompasses digital watches right up to ultra-high resolution displays. For the latter, each pixel can display one colour to another, activated by the variable voltage-switching from the pixels" transistors, detailed above. Faster switching between opposing colours (usually black-to-white), quoted in milliseconds, is usually a reasonable indicator of the panel"s effectiveness in displaying fast-moving images. The lower the ms time, the less time needed to redraw an image and, consequently, the lower the chance of ghosting or smearing when displaying fast-moving images. Manufacturers often have different methods of determining pixel response time, so it requires a little time investment on your part, to correctly determine whether the quoted figures between competing manufacturers is a consistent measure.

LCDs can be defined by the technology used to control the amount of refracted light (and by inference, colour) passing through from the source to your eyes. Broadly speaking, three technologies exist, and each has its own benefits and disadvantages. Twisted Nematic (TN) LCDs literally twist the liquid crystals in the display. The greater the twisting, controlled by the pixels" transistors, the less light passes through the LCD. Colours can then displayed in relation to just how much light is being passed through each pixel. This approach offers fast colour switching (response time) but usually at the cost of poor colour rendition for dark colours, especially blacks.

The use of millions of transistors to create an electric field around liquid crystals can lead to the unwanted side-effect of dead/stuck-on (sub)pixels, arising from transistors not working correctly and thus not applying the correct voltage (or at all) to the LCs. LCD manufacturers generally claim that a non-perfect screen, that is, one with a small number of erroneously behaving pixels is a by-product of keeping LCD costs down. Recently, though, advances in manufacturing have allowed certain manufacturers to offer a zero bright-dot policy, where the display will be replaced if it ships with dead pixels.

LCDs are usually offered in a number of sizes, measured from corner to corner, with the display"s native resolution (number of vertical and horizontal pixels) and pixel pitch largely determining the optimum size. Pixel pitch, the space taken up by a single pixel, defined in miilimetres, usually ranges from 0.2mm-0.3mm. A lower pixel pitch adds in more pixels for a given size of display, thereby offering a sharper image. We"ve listed a number of LCD sizes and the native resolutions you"re likely to find with each.

WD=Widescreen The above table highlights a couple of interesting factors that need to be taken into account when considering an LCD monitor purchase. The jump from a 19" to 20" LCD is accompanied by a near-doubling of street price. Typically, 19" panels ship with an SXGA resolution and 20" screens with UXGA. The UXGA panels" pixel count is almost 50% higher than 19" models, leading to a lower pixel pitch and far greater pixel density. Consumers looking to invest in an LCD monitor for CAD modelling and video-editing purposes, for example, will be best served with panels with the greatest pixel density, so whilst 30-inch wide-aspect panels have the greatest screen estate from the selection above, the ultra-high WQXGA resolution ensures that they carry the lowest pixel pitch.

LCDs can also be defined in terms of brightness and contrast ratios. You"ll often see, for example, a particular panel quoted as having 500cd/m² (nits) brightness and a contrast of 1000:1. The brightness figure refers to the candela per square metre, with a higher figure offering greater brightness levels than a lower one. The contrast ratio is defined as the ratio difference in light intensity between the whitest white and deepest black. A higher nits figure and contrast ratio generally gives rise to a brighter screen with better colour representation.

Low-end LCD monitors tend to ship with analogue inputs, fed into the screen via an HD15 or DVI-I cable. Graphics cards natively output digital video signals, so having to convert between digital-to-analog at the source and back from analog-to-digital at the LCD"s end adds in the possibility of an inferior image than from a straight digital-to-digital (DVI-D) link, where digital inputs exist on higher-specified models. The degree of I.Q. inferiority between analogue and digital inputs is dependant upon the quality of the panel"s convertor, and it"s always preferable to use DVI-D for the cleanest, sharpest image quality. LCDs may well have both analogue and digital inputs, and switching between the two is usually just a matter of pressing a mode-select button.

LCD monitors may also carry a number of other inputs, including S-Video and composite. Again, it"s worth checking the exact specifications of each panel, to correctly determine the inputs on offer.

The current LCD monitor market is dominated by a handful of players who manufacture the displays themselves. Samsung, LG Philips, and AU are the most cited manufacturers, and virtually every retail LCD, be it Dell, Acer or HP, contains a panel from one of the trio. Advances in LCD design have lead to a lowering of cost, increases in panel performance, and lower instances of multi-defective pixels on a single display.

Year on year LCD panel manufacturers raise the bar with respect to response time, brightness and contrast ratio. A £300 20-inch UXGA panel today, then, is undoubtedly better than a similar £1,000 panel released 3 years ago. Each passing month brings the retail price of a particular type/size of display down a notch or two, and it is possible to buy a perfectly decent 19-inch DVI-capable LCD monitor for <£200. This is precisely why bulky, unwieldy CRTs are now a dying breed, and the low pixel response time, high brightness and contrast ratio figures of current LCD monitors make them a reasonable choice for fast-paced gaming, too.

A recent trend has been to introduce PC-orientated LCD monitors with wide-aspect displays, usually with a 16:10 viewing ratio, that work well as multimedia monitors for playing back content. We expect this trend to continue unabated throughout 2006. We also expect LCD manufacturers to further reduce black-to-white pixel response time with each new iteration of panel, making ghosting/smearing in fast-moving games a thing of the past.

Consumers looking for a LCD monitor to fit a particular budget are urged to check the panel"s response time, evaluate its brightness and contrast ratio in relation to its competition, and to make a note of its inputs. The maturity of the underlying technology and stiffness of competition is such that it is difficult to buy a bad LCD now. It always pays to do your research, though!

Leadtek has paid great efforts on research and development of TFT-LCM, especially on its application of consumable and industrial products. The sizes of LCM includes 1.4”, 2.4”, 3.5", 3.51", 4.3", 4", 5", 7", 8", 10.1” and 11.6". And among them the 3.5”, 4.3", 5", 7” and 10.1" LCM has achieved the leading level of the industry, and mainly applied to vehicle-applications, tablet PCs, smartphones, medical equipment, measurement equipment, E-books, EPC and industrial products, and provides powerful and reliable supports on supplies and qualities. We are cooperating with famous foreign companies on research and developments, and will bring out the series products of industrial control LCD display. Also, we explore the overseas market, and build up a long-term relationship with our overseas partners and agents, Leadtek products will be worldwide in the near future.