tft lcd displays wide viewing angles quotation

A TN or Twisted Nematic TFT LCD is a cost-effective high performance LCD. It offers good brightness performance and fast response times. However, it suffers in one key area and that is its viewing cone. TN LCD’s typically have three good viewing angle directions. In these directions the image is typically clear and colors are consistent up to 80 degrees from the center of the LCD. The remaining viewing direction is usually good through 40-50 degrees from center. Afterwards, the image is likely to invert, almost appearing like an x-ray.

Logic Technologies began it"s life as a custom display design and manufacturing company back in 2008. Over the past 8 years we have developed hundreds of custom display solutions from 1.1" TFT displays for gaming button consoles, small true transflective TFTs, ruggedised 7" TFT and Touch Panel modules all the way to full-customised 15" computers, complete with IP67-rated stainless steel housing for ruggedized environments.

This TFT display module comprises a 7" TFT with capacitive touch and an EVE accelerator PCB. The EVE accelerator PCB simplifies interfacing with the display as it makes the display, touch, backlight, and any added audio features appear to the host MCU as a memory-mapped SPI device. The host controller can send high-level commands to the EVE chip to quickly and easily describe images, text, buttons, tables, and more.

At 7" on the diagonal, this display offers plenty of space, making it a great choice for an information panel, menu, etc. Plus, thanks to the extremely wide viewing angle achieved using in-plane switching (IPS), this display can be read equally well above or below eye level.

IPS (In-Plane Switching) lcd is still a type of TFT LCD, IPS TFT is also called SFT LCD (supper fine tft ),different to regular tft in TN (Twisted Nematic) mode, theIPS LCD liquid crystal elements inside the tft lcd cell, they are arrayed in plane inside the lcd cell when power off, so the light can not transmit it via theIPS lcdwhen power off, When power on, the liquid crystal elements inside the IPS tft would switch in a small angle, then the light would go through the IPS lcd display, then the display on since light go through the IPS display, the switching angle is related to the input power, the switch angle is related to the input power value of IPS LCD, the more switch angle, the more light would transmit the IPS LCD, we call it negative display mode.

The regular tft lcd, it is a-si TN (Twisted Nematic) tft lcd, its liquid crystal elements are arrayed in vertical type, the light could transmit the regularTFT LCDwhen power off. When power on, the liquid crystal twist in some angle, then it block the light transmit the tft lcd, then make the display elements display on by this way, the liquid crystal twist angle is also related to the input power, the more twist angle, the more light would be blocked by the tft lcd, it is tft lcd working mode.

A TFT lcd display is vivid and colorful than a common monochrome lcd display. TFT refreshes more quickly response than a monochrome LCD display and shows motion more smoothly. TFT displays use more electricity in driving than monochrome LCD screens, so they not only cost more in the first place, but they are also more expensive to drive tft lcd screen.The two most common types of TFT LCDs are IPS and TN displays.

As an active-matrix LCD device, the TFT LCD’s individual pixels consist of red, green, and blue sub-pixels, each with their own TFT and electrodes beneath them. These sub-pixels are controlled individually and actively, hence the name active-matrix; this then allows for smoother, fast response time. The active-matrix also allows for larger display modes that continue to uphold quality of color, refresh rate, and resolution when aspect ratio is increased.

Within the pixels composing the TFT LCD display, electrodes play a role in conducting the circuit between them. If layered on both insides of the two glass substrates, the electrodes, along with the TFT, create an electrical pathway within the liquid crystal layer. There are also other placements of electrodes besides on the surface and back of the device that change the effect of the electrical pathway between the substrates (to be discussed later in this article). This pathway has an effect on the crystals through its electric field, which is one of the TFT concepts responsible for the low, minimized power consumption of TFTs, making them so efficient and appealing.

Though there are a variety of ways to align the crystal molecules, using a twisted nematic (TN) to do so is one of the oldest, most common, and cheapest options for LCD technology. It uses the electric field between the electrodes organized with one on the surface substrate layer and the other on the back substrate layer to manipulate the liquid crystals.

Though this is one of the cheapest options for display technology, it has its own problems. The TN TFT LCD does not have top response times compared to other types, and it does not provide for as wide a viewing angle as other TFT LCDs using different alignment methods. A viewing angle is the direction at which a screen can be looked at before the displayed image cannot be seen properly in terms of light and color. TN displays mostly struggle with vertical viewing angles but also have somewhat limited horizontal angles as well. This TN LCDs viewing angle limit is called the gray scale inversion issue.

Generally, when viewing angle is not ideal, image quality as a whole decreases. Things like contrast ratio (the luminance ratio between the brightest white and darkest black) and readability of the screen are not preserved due to this issue.

Among the methods of liquid crystal alignment, TN is only one option for LCD technology. There are various other common ways to align the crystals for a wide viewing angle, such as the multi-domain vertical alignment or in-plane switching. In addition, because of the abundance of TN devices, something called O-film has also been introduced to pair with TN screens so that users do not have to buy whole new devices.

Simply put, this method divides the cell beneath each pixel into multiple domains. With the division, molecules in the same cell can be oriented differently, and so as users shift their views of the display, there are different crystal directional alignments that allow for the preservation of the display properties over these angles such as high brightness and high contrast. This solves the problem of what is known as a mono-domain vertical alignment.

Though mostly similar to the TN, the MVA has one notable feature in its cell that TN cells do not have: glass protrusions. Between the sandwiching electrodes, angles glass protrusions reorient the light traveling within the layer so that when exiting the surface polarizer, it travels in a multitude of directions to satisfy the need for a wide viewing angle.

In recent developments of the MVA TFT LCD, contrast ratio, brightness, and response times have all increased in quality. Contrast ratio, being 300:1 when first developed in 1997, has been improved to 1000:1. Similarly, response time, characterized by rising (black to white) and decay (white to black) time, has reached times that are the fastest that human eyes can process, demonstrating the appropriateness of MVA-based displays for moving images.

With this type of alignment, viewing angles were preserved in much wider directions compared to the TN. Recently, IPS displays have improved qualities like response time to make the IPS screens more desirable to consumers. However, this type of TFT LCD will tend to cost more than TN devices.

While the TN TFT LCD has the smallest cost, that is for a reason. O-films, MVAs, and IPS TFT LCDs have greater costs due to their more intricate technologies that improve viewing angle to retain resolution and general display quality.

The O-film specifically is unique because rather than changing the liquid crystal alignment technology and for a relatively low cost, it can swap the surface polarizer of a TN device with a special film to widen the viewing angle. Because it is combined with TN, it can only improve viewing angle slightly.

IPS has the most potential for improved viewing angle, reaching higher possible angles than all the other options. With IPS, though, there is a higher power consumption than the regular TN device due to the need for a brighter backlight in this device.

All these technologies are viable options depending on the consumer’s desires and price range. MVA and IPS TFT LCDs tend to be more practical for consumer products like LCD monitors and phone screens, while TN and O-film LCDs can cross over into industrial applications. Nonetheless, with the growth of the IPS and MVA LCDs, their applications are widening.

The AFFS is similar to the IPS in concept; both align the crystal molecules in a parallel-to-substrate manner, improving viewing angles. However, the AFFS is more advanced and can better optimize power consumption. Most notably, AFFS has high transmittance, meaning that less of the light energy is absorbed within the liquid crystal layer and more is transmitted towards the surface. IPS TFT LCDs typically have lower transmittances, hence the need for the brighter backlight. This transmittance difference is rooted in the AFFS’s compact, maximized active cell space beneath each pixel.

Since 2004, Hydis, who developed the AFFS, has licensed the AFFS to the Japanese company Hitachi Displays, where people are developing complicated AFFS LCD panels. Hydis has improved display properties like outdoor readability of the screen, making it even more appealing to use for its main application: mobile phones displays.

Displaytech IPS displays are the premium option within our standard TFT LCDs. Our IPS TFT displays offer improved color accuracy and crisper images compared to non-IPS displays of the same size. They also provide a very wide viewing angle and a high refresh rate of the screen’s contents.

IPS screens have a special technology within the liquid crystals that allow the screen’s contents to maintain color and overall visibility from any viewing direction. This enhances the user experience since the user can interact with the LCD from any vantage point.

Get rich colors, detailed images, and bright graphics from an LCD with a TFT screen. Our standard Displaytech TFT screens start at 1” through 7” in diagonal size and have a variety of display resolutions to select from. Displaytech TFT displays meet the needs for products within industrial, medical, and consumer applications.

TFT displays are LCD modules with thin-film transistor technology. The TFT display technology offers full color RGB showcasing a range of colors and hues. These liquid crystal display panels are available with touchscreen capabilities, wide viewing angles, and bright luminance for high contrast.

Our TFT displays have LVDS, RGB, SPI, and MCU interfaces. All Displaytech TFT LCD modules include an LED backlight, FPC, driver ICs, and the LCD panel.

We offer resistive and capacitive touch screens for our 2.8” and larger TFT modules. Our TFT panels have a wide operating temperature range to suit a variety of environments. All Displaytech LCDs are RoHS compliant.

We also offer semi-customization to our standard TFT screens. This is a cost-optimized solution to make a standard product better suit your application’s needs compared to selecting a fully custom TFT LCD. Customizations can focus on cover glass, mounting / enclosures, and more - contact us to discuss your semi-custom TFT solution.

LCD stands for “Liquid Crystal Display” and TFT stands for “Thin Film Transistor”. These two terms are used commonly in the industry but refer to the same technology and are really interchangeable when talking about certain technology screens. The TFT terminology is often used more when describing desktop displays, whereas LCD is more commonly used when describing TV sets. Don’t be confused by the different names as ultimately they are one and the same. You may also see reference to “LED displays” but the term is used incorrectly in many cases. The LED name refers only to the backlight technology used, which ultimately still sits behind an liquid crystal panel (LCD/TFT).

As TFT screens are measured differently to older CRT monitors, the quoted screen size is actually the full viewable size of the screen. This is measured diagonally from corner to corner. TFT displays are available in a wide range of sizes and aspect ratios now. More information about the common sizes of TFT screens available can be seen in our section about resolution.

The aspect ratio of a TFT describes the ratio of the image in terms of its size. The aspect ratio can be determined by considering the ratio between horizontal and vertical resolution.

16:9 = wide screen formats such as 1920 x 1080 and 2560 x 1440. 16:9 is commonly used for multimedia displays and TV’s and is increasingly becoming the standard

The resolution of a TFT is an important thing to consider. All TFT’s have a certain number of pixels making up their liquid crystal matrix, and so each TFT has a “native resolution” which matches this number. It is always advisable to run the TFT at its native resolution as this is what it is designed to run at and the image does not need to be stretched or interpolated across the pixels. This helps keep the image at its most clear and at optimum sharpness. Some screens are better than others at running below the native resolution and interpolating the image which can sometimes be useful in games.

You generally cannot run a TFT at a resolution of above its native resolution although some screens have started to offer “Virtual” resolutions, for example “virtual 4k” where the screen will accept a 3840 x 2160 input from your graphics card but scale it back to match the native resolution of the panel which is often 2560 x 1440 in these examples. This whole process is rather pointless though as you lose a massive amount of image quality in doing so.

Ultra-high resolutions must be thought of in a slightly different way. Ultra HD (3840 x 2160) and 4K (4096 x 2160) resolutions are being provided nowadays on standard screen sizes like 24 – 27” for instance. Traditionally as you increased the resolution of panels it was about providing more desktop real estate to work with. However, with those resolutions being so high, and the screen size being relatively small still, the image and text becomes incredibly small if you run the screen at normal scaling at those native resolutions. For instance imagine a 3840 x 2160 resolution on a 24” screen compared with 1920 x 1080. The latter would probably be considered a comfortable font size for most users. These ultra-high resolutions nowadays are about improving image clarity and sharpness, and providing a higher pixel density (measured as pixels per inch = PPI). In doing so, you can improve the sharpness and clarity of an image much like Apple have famously done with their “Retina” displays on iPads and iPhones. To avoid complications with tiny images and fonts, you will then need to enable scaling in your operating system to make everything easier to see. For instance if you enabled scaling at 150% on a 3840 x 2160 resolution, you would end up with a screen real estate equivalent to a 2560 x 1440 panel (3840 / 1.5 = 2560 and 2160 / 1.5 = 1440). This makes text much easier to read and the whole image a more comfortable size, but you then get additional benefits from the higher pixel density instead, which results in a sharper and crisper image.

Generally you will need to take scaling in to consideration when purchasing any ultra-high resolution screen, unless it’s of a very large size. The scaling ability does vary however between different operating systems so be careful. Apple OS and modern Windows (8 and 10) are generally very good at handling scaling for ultra-high res displays. Older operating systems are less capable and may sometimes be complicated. You will also find varying support from different applications and games, and often end up with weird sized fonts or sections that are not scaled up and remain extremely small. A “standard” resolution where you don’t need to worry about scaling might be simpler for most users.

Unlike on CRT’s where the dot pitch is related to the sharpness of the image, the pixel pitch of a TFT is related to the distance between pixels. This value is fixed and is determined by the size of the screen and the native resolution (number of pixels) offered by the panel. Pixel pitch is normally listed in the manufacturers specification. Generally you need to consider that the ‘tighter’ the pixel pitch, the smaller the text will be, and potentially the sharper the image will be. To be honest, monitors are normally produced with a sensible resolution for their size and so even the largest pixel pitches return a sharp images and a reasonable text size. Some people do still prefer the larger-resolution-crammed-into-smaller-screen option though, giving a smaller pixel pitch and smaller text. It’s down to choice and ultimately eye-sight.

For instance you might see a 35″ ultra-wide screen with only a 2560 x 1080 resolution which would have a 0.3200 mm pixel pitch. Compare this to a 25″ screen with 2560 x 1400 resolution and 0.2162 mm pixel pitch and you can see there will be a significant different in font size and image sharpness. There are further considerations when it comes to the pixel pitch of ultra-high resolution displays like Ultra HD and 4K. See the section on PPI for more information.

Instead manufacturers are now focusing on delivering higher resolutions in to existing panel sizes, not for the purpose of providing more desktop real-estate, but for the purpose of improving image sharpness and picture quality. Apple started this trend with their “Retina Displays” used in iPads and iPhones, improving image sharpness and clarity massively. It is common now to see smaller screens such as 24″ and 27″ for instance, but with high resolutions like 3840 x 2160 (Ultra HD) or even 5120 x 2880 (5K). By packing more pixels in to the same screen size which would typically offer a 2560 x 1440 resolution, panel manufacturers are able to provide much smaller pixel pitches and improve picture sharpness and clarity. To measure this new way of looking at resolution you will commonly see the spec of ‘Pixels Per Inch’ (PPI) being used.

While this aspect is not always discussed by display manufacturers it is a very important area to consider when selecting a TFT monitor. The LCD panels producing the image are manufactured by many different panel vendors and most importantly, the technology of those panels varies. Different panel technologies will offer different performance characteristics which you need to be aware of. Their implementation is dependent on the panel size mostly as they vary in production costs and in target markets. The four main types of panel technology used in the desktop monitor market are:

TN Film was the first panel technology to be widely used in the desktop monitor market and is still regularly implemented in screens of all sizes thanks to its comparatively low production costs. TN Film is generally characterized by good pixel responsiveness making it a popular choice for gamer-orientated screens. Where overdrive technologies are also applied the responsiveness is improved further. TN Film panels are also available supporting 120Hz+ refresh rates making them a popular choice for stereoscopic 3D compatible screens. While older TN Film panels were criticized for their poor black depth and contrast ratios, modern panels are actually very good in this regard, often producing a static contrast ratio of up to 1000:1. Perhaps the main limitation with TN Film technology is its restrictive viewing angles, particularly in the vertical field. While specs on paper might look promising, in reality the viewing angles are restrictive and there are noticeable contrast and gamma shifts as you change your line of sight. TN Film panels are normally based around a 6-bit colour depth as well, with a Frame Rate Control (FRC) stage added to boost the colour palette. They are often excluded from higher end screens or by colour enthusiasts due to this lower colour depth and for their viewing angle limitations. TN Film panels are regularly used in general lower end and office screens due to cost, and are very popular in gaming screens thanks to their low response times and high refresh rate support. Pretty much all of the main panel manufacturers produce TN Film panels and all are widely used (and often interchanged) by the screen manufacturers.

IPS was originally introduced to try and improve on some of the drawbacks of TN Film. While initially viewing angles were improved, the panel technology was traditionally fairly poor when it came to response times and contrast ratios. Production costs were eventually reduced and the main investor in this technology has been LG.Display (formerly LG.Philips). The original IPS panels were developed into the so-called Super IPS (S-IPS) generation and started to be more widely used in mainstream displays. These were characterized by their good colour reproduction qualities, 8-bit colour depth (without the need for Frame Rate Control) and very wide viewing angles. These panels were traditionally still quite slow when it came to pixel response times however and contrast ratios were mediocre. In more recent years a change was made to the pixel alignment in these IPS panels (see our detailed panel technology article for more information) which gave rise to the so-called Horizontal-IPS (H-IPS) classification. With the introduction of overdrive technologies, response times were improved significantly, finally making IPS a viable choice for gaming. This has resulted more recently in IPS panels being often regarded as the best all-round technology and a popular choice for display manufacturers in today’s market. Improvements in energy consumption and reduced production costs lead to the generation of so-called e-IPS panels. Unlike normal 8-bit S-IPS and H-IPS classification panels, the e-IPS generation worked with a 6-bit + FRC colour depth. Developments and improvements with colour depths also gave rise to a generation of “10-bit” panels with some manufacturers inventing new names for the panels they were using, including the co-called Performance-IPS (p-IPS). It is important to understand that these different variants are ultimately very similar and the names are often interchanged by different display vendors. For more information, see our detailed panel technologies guide.

Nowadays IPS panels are produced and developed by several leading panel manufacturers. LG.Display technically own the IPS name and continue to invest in this popular technology. Samsung began production of their very similar PLS (Plane to Line Switching) technology, as did AU Optronics with their AHVA (Advanced Hyper Viewing Angle). These are all so similar in performance and features that they can be simply referred to now as “IPS-type”. Indeed monitor manufacturers will normally stick to the common IPS name but the underlying panel may be produced by any number of different manufacturers investing in this type of panel tech. AU Optronics have done a good job with finally increasing the refresh rate of their IPS panels, and making them a more viable option for gamers. Native 144Hz IPS-type panels are now available and response times continue to be reduced as well. Modern IPS panels are characterized by decent response times, if not quite as fast as TN Film they are certainly more fluid than older panels. Contrast ratios are typically around 1000:1 and viewing angles continue to be the widest and most stable of any panel technology. You will find varying colour depths including 6-bit+FRC and 8-bit commonly being used, although this makes little difference in practice. One of the remaining limitations with IPS-type technologies are the so-called “IPS glow”, where darker content introduces a pale glow when viewed from an angle. It’s a characteristic of the panel technology and pretty hard to avoid without additional filters being added to the panels. On larger and wider screens some people find this glow distracting and problematic.

The original early VA panels were quickly scrapped due to their poor viewing angles, and in their place came the two main types of VA matrix. Multi-Domain Vertical Alignment (MVA) and Patterned Vertical Alignment (PVA) panels. These VA variants were characterized by their reasonably wide viewing angles, being better than TN Film but not as wide as IPS. They were originally poor when it came to pixel response times but offered 8-bit colour depths and the best static contrast ratios of all the technologies discussed here. Traditionally VA panels were capable of static contrast ratios of around 1000 – 1200:1 but this has even been improved now to 3000:1 and above. Until very recently VA panels remained very slow and so were not really suitable for gaming. However during 2012 we saw advancements with the latest generation of VA panels and through the use of overdrive technologies this has been significantly improved. Perhaps the main limitation with VA panels is still their viewing angles when compared with popular IPS panel options. Gamma and contrast shifts can be an issue and the technology also suffers from an inherent off-centre contrast shift issue which can be distracting to some users. Through the years we have seen several different generations of VA panels. AU Optronics are the main manufacturer of MVA matrices, and we have seen the so-called Premium-MVA (P-MVA) and Advanced-MVA (AMVA) generations emerge. Chi Mei Innolux (previously Chi Mei Optoelectronics / CMO) also make their own variant of MVA which they call Super-MVA (S-MVA).The only manufacturer of PVA panels is Samsung as it is their own version of VA technology. We have seen several generations from them including Super-PVA (S-PVA) and cPVAandSVA. For more information, see our detailed panel technologies guide.

This technology was developed by Sharp for use in some of their TFT displays. It consists of several improvements that Sharp claim to have made, mainly to counter the drawbacks of the popular TN Film technology. They have introduced an Anti-Glare / Anti-Reflection (AGAR) screen coating which forms a quarter-wavelength filter. Incident light is reflected back from front and rear surfaces 180° out of phase, thus canceling reflection rather diffusing it as others do. As well as reducing glare and reflection from the screen, this is marketed as being able to offer deeper black levels. Sharp also claim to offer better contrast ratios than any competing technology (VA and IPS); but with more emphasis on improving these other technologies, this is probably not the case with more modern panels. There are very few ASV monitors around really, with the majority of the market being dominated by TN, VA and IPS panels.

This technology was developed by BOE Hydis, and is not really very widely used in the desktop TFT market, more in the mobile and tablet sectors. It is worth mentioning however in case you come across displays using this technology. It was developed by BOE Hydis to offer improved brightness and viewing angles to their display panels and claims to be able to offer a full 180/180 viewing angle field as well as improved colours. This is basically just an advancements from IPS and is still based on In Plane technology. They claim to “modify pixels” to improve response times and viewing angles thanks to improved alignment. They have also optimised the use of the electrode surface (fringe field effect), removed shadowed areas between pixels, horizontally aligned electric fields and replaced metal electrodes with transparent ones. More information about AFFS can be found here.

This panel technology was developed by NEC LCD, and is reported to offer wide viewing angles, fast response times, high luminance, wide colour gamut and high definition resolutions. Of course, there is a lot of marketing speak in there, and the technology is not widely employed in the mainstream monitor market. Wide viewing angles are possible thanks to the horizontal alignment of liquid crystals when electrically charged. This alignment also helps keep response times low, particularly in grey to grey transitions. Their SFT range also offers high definition resolutions and are commonly used in medical displays where extra fine detail is required.

NEC’s SFT technology was first developed to be labelled as Advanced-SFT (A-SFT) which offered enhanced luminance figures. This then developed further to Super Advanced-SFT (SA-SFT) where colour gamut reached 72% of the NTSC colour space, and then to Ultra Advanced-SFT (UA-SFT) where the gamut was still at 72% or higher, but with a further enhancement of the luminance as compared with SA-SFT. These changes were all made possible thanks to the improved transmissivity of the SFT technology. More information is available from NEC LCD

Take for instance this example response time graph (rise times from 0 > x) I have put together. The X-axis defines the grey scale ranging from code 0 to code 255, and the Y-axis shows the response time across this range. As you progress to the right of the graph, the transitions are getting progressively lighter. So for instance at code 100 the transition is from black > dark grey, but at code 200 the transition is from black > light grey. At code 255, this is the change from black > white and is traditionally the fastest transition. It is the fastest because this is the widest change and therefore the largest voltage is applied to the liquid crystals. For many years, manufacturers have quoted the fastest transition of the panel as the figure for ‘response time’. This was always at the black > white > black transition and so this became accepted as the ISO standard norm for measuring response time. If this graph were a real panel, it would very likely be quoted as a 10ms screen and shows a characteristic curve for a traditional, non-overdriven, TN Film panel.

One thing to note regarding pixel response time is that the overall performance of the TFT will also depend on the technology of the panel used. TN film panels offer response time graphs similar to that above, but screens based on traditional VA / IPSvariant panels can show response time graphs more like this (we are assuming for now non-overdriven panels):

Some reviews sites including TFTCentral have access to advanced photosensor (photodiodе + low-noise operational amplifier) and oscilloscope measurement equipment which allows them to measure response time as detailed above. See our article about response times for more information on that method. Graphs showing response time according to their equipment are produced. Other sites rely on observed responsiveness to compare how well a panel can perform in practice and what a user might see in normal use. We think it is important to study both methods if possible to give a fuller picture of a panels performance. For visual tests TFTCentral uses a program called PixPerAn (developed by Prad.de) which is good for comparing monitor responsiveness with its series of tests. The favourite seems to be the moving car test as shown here:

In addition to pixel response time measurements and visual tests described above, it is also possible to capture the levels of blurring and smearing the human eye will experience on a display. This is achieved using a pursuit camera setup. They are simply cameras which follow the on-screen motion and are extremely accurate at measuring motion blur, ghosting and overdrive artefacts of moving images. Since they simulate the eye tracking motion of moving eyes, they can be useful in giving an idea of how a moving image appears to the end user. It is the blurring caused by eye tracking on continuously-displayed refreshes (sample-and-hold) that we are keen to analyse with this new approach. This is not pixel persistence caused by response times; but a different cause of display motion blur which cannot be captured using static camera tests. Low response times do have a positive impact on motion blur, and higher refresh rates also help reduce blurring to a degree. It does not matter how low response times are, or how high refresh rates are, you will still see motion blur from LCD displays under normal operation to some extent and that is what this section is designed to measure. Further technologies specifically designed to reduce perceived motion blur are required to eliminate the blur seen on these type of sample-and-hold displays which we will also look at.

These tests capture the kind of blurring you would see with the naked eye when tracking moving objects across the screen (example from the Asus ROG Swift PG279Q). As you increase the refresh rate the perceived blurring is reduced, as refresh rate has a direct impact on motion blur. It is not eliminated entirely due to the nature of the sample-and-hold LCD display and the tracking of your eyes. No matter how fast the refresh rate and pixel response times are, you cannot eliminate the perceived motion blur without other methods.Tests like the above would give you an idea of the kind of perceived motion blur range when using the particular screen without any bur reduction mode active.

The Contrast Ratio of a TFT is the difference between the darkest black and the brightest white it is able to display. This is really defined by the pixel structure and how effectively it can let light through and block light out from the backlight unit. As a rule of thumb, the higher the contrast ratio, the better. The depth of blacks and the brightness of the whites are better with a higher contrast ratio. This is also referred to as the static contrast ratio.

When considering a TFT monitor, a contrast ratio of 1000:1 is pretty standard nowadays for TN Film and IPS-type panels. VA-type panels can offer static contrast ratios of 3000:1 and above which are significantly higher than other competing panel technologies.

Some technologies boast the ability to dynamically control contrast (Dynamic Contrast Ratio – DCR) and offer much higher contrast ratios which are incredibly high (millions:1 for instance!). Be wary of these specs as they are dynamic only, and the technology is not always very useful in practice. Traditionally, TFT monitors were said to offer poor black depth, but with the extended use of VA panels, the improvements from IPS and TN Film technology, and new Dynamic Contrast Control technologies, we are seeing good improvements in this area. Black point is also tied in to contrast ratio. The lower the black point, the better, as this will ensure detail is not lost in dark image when trying to distinguish between different shades.

Brightness as a specification is a measure of the brightest white the TFT can display, and is more accurately referred to as its luminance. Typically TFT’s are far too bright for comfortable use, and the On Screen Display (OSD) is used to turn the brightness setting down. Brightness is measure in cd/m2 (candella per metre squared). Note that the recommended brightness setting for a TFT screen in normal lighting conditions is 120 cd/m2. Default brightness of screens out of the box is regularly much higher so you need to consider whether the monitor controls afford you a decent adjustment range and the ability to reduce the luminance to a comfortable level based on your ambient lighting conditions. Different uses may require different brightness settings as well so it is handy when reviews record the luminance range possible from the screen as you adjust the brightness control from 100 to 0%.

The colour depth of a TFT panel is related to how many colours it can produce and should not be confused with colour space (gamut). The more colours available, the better the colour range can potentially be. Colour reproduction is also different however as this related to how reliably produced the colours are compared with those desired.

Colour gamut in TFT monitors refers to the range of colours the screen is capable of displaying, and how much of a given reference colour space it might be able to display. It is ultimately linked to backlight technology and not to the panel itself.

Laser Displays are capable of producing the biggest colour gamut for a system with three basic colours, but even a laser display cannot reproduce all the colours the human eye can see, although it is quite close to doing that. However, in today’s monitors, both CRT and LCD (except for some models I’ll discuss below), the spectrum of each of the basic colours is far from monochromatic. In the terms of the CIE diagram it means that the vertexes of the triangle are shifted from the border of the diagram towards its centre.

Traditionally, LCD monitors were capable of giving approximate coverage of the sRGB reference colour space as shown in the diagram above. This is defined by the backlighting used in these displays – Cold-cathode fluorescent lamps (CCFL) that are employed which emit radiation in the ultraviolet range which is transformed into white colour with the phosphors on the lamp’s walls. These backlight lamps shine through the LCD panel, and through the RGB sub-pixels which act as filters for each of the colours. Each filter cuts a portion of spectrum, corresponding to its pass-band, out of the lamp’s light. This portion must be as narrow as possible to achieve the largest colour gamut.

To help develop and improve on the colour space a screen is capable of displaying a new generation CCFL backlighting was introduced. These so-called “wide gamut” backlights allow a gamut coverage of typically 92 – 102% of the NTSC colour space. There is a difference in practice which all users should be able to detect. The colour space available is extended mainly in green shades as you can see from the image above. Red coverage is also extended in some cases. This extended colour space sounds appealing on face value since the screens featuring WCG-CCFL backlighting can offer a broader range of colours. Manufacturers will often promote the colour space coverage of their screens with these high figures. In practice you need to consider what impact this would have on your use.

It’s important to consider what colour space your content is based around. sRGB has long been the preferred colour space of all monitors, and is in fact the reference for the Windows operating system and the internet. As such, most content an average user would ever use is based on sRGB. If you view sRGB content on a wide gamut screen then this can lead to some colours looking incorrect as they are not mapped correctly to the output device. In practice this can lead to oversaturation, and greens and reds can often appear false, oversaturated or neon-like. Colour managed applications and a colour managed workflow can prevent this but for the average user the cross-compatibility of widely used sRGB content and a wide gamut screen may present problems and prove troublesome. Some users don’t object to the over saturated and ‘cartoony’ colours for their use, but to many, it is an issue.

Of course the opposite is true if in fact you are working with content which is based on a wider colour space. In photography, the Adobe RGB colour space is often used and is wider than the sRGB reference. If you are working with wide gamut content, with wide gamut supported applications, you would want a screen that can correctly display the full range of colours. This could not be achieved using a traditional CCFL backlit display with only sRGB coverage, and so a wide gamut screen would be needed. Wide gamut displays are often aimed at colour enthusiasts and professional uses as a result.

A compromise is sometimes available in the form of a screen which can support a range of colour spaces accurately. Some higher end screens come with a wide gamut backlight unit. Natively these offer a gamut covering 92 – 102% of the NTSC colour space. However, they also feature emulation modes which can simulate a smaller colour space. These emulation modes are normally available through the OSD menu and offer varying options with varying degrees of reliability. In the best cases the screens can emulate the smaller Adobe RGB colour space, and also the sRGB colour space. This allows the user to work in whichever colour space they prefer but gives them compatibility with a wider range of content if they have the need. The success of these colour space emulations will vary from one screen to another however and are not always accurate. Obviously you are still paying additional money for the wide gamut support, so if you’re only really interested in using sRGB mode then you’d probably be better looking for a standard gamut backlit screen.

LED backlighting has now become the norm for desktop monitors and is available in a few variations. The most common is White-LED (W-LED), which is a replacement for standard CCFL backlighting. The LED’s are placed in a line along the edge of the matrix, and the uniform brightness of the screen is ensured by a special design of the diffuser. The colour gamut is limited to sRGB as standard (around 68 – 72% NTSC) but the units are cheaper to manufacturer and so are being utilised in more and more screens, even in the more budget range. They do have their environmental benefits as they can be recycled, and they have a thinner profile making them popular in super-slim range models and notebook PC’s. It is possible to extend the colour gamut of W-LED displays using “Quantum Dot” technologies which are fairly new.

RGB LED backlighting consists of an LED backlight based on RGB triads, each triad including one red, one green and one blue LED. With RGB LED backlighting the spectrum of each LED is rather wide, so their radiation can’t be called strictly monochromatic and they can’t match a laser display, yet they are much better than the spectrum of CCFL and WCG-CCFL backlighting. RGB LED backlighting is not common yet in desktop monitors, and their price tends to put them way above the budget of all but professional colour enthusiast and business users. These models using RGB LED backlights are capable of offering a gamut covering > 114% of the NTSC colour space. They are not really used at all nowadays as they were prohibitively expensive.

There are also wide gamut LED backlights available and more commonly used nowadays as they are cheaper to manufacturer than older RGB LED versions. GB-r-LED for instance is provided by LG.Display and can offer wide gamut support from an LED backlight. Other panel manufacturers have their equivalents as well. Modern LED screens with wide gamut support tend to have a percentage coverage of the Adobe RGB reference space listed in the display spec, with 99% Adobe RGB being pretty standard for wide gamut LED technologies.

You will commonly see a monitor’s gamut listed as a percentage compared with a reference colour space. This will vary depending on which reference a manufacturer uses, but commonly you will see a % against the NTSC or Adobe RGB colour spaces. Bear in mind also that the gamut / colour space of the sRGB standard equates to about 72 – 75% of the NTSC reference. This is the standard colour space for the Windows operating system and the internet, and so where extended colour spaces are produced from a monitor, considerations need to be made as to the colour space of the content you are viewing.

Viewing angles are quoted in horizontal and vertical fields and often look like this in listed specifications: 170/160 (170° in horizontal viewing field, 160° in vertical). The angles are related to how the image looks as you move away from the central point of view, as it can become darker or lighter, and colours can become distorted as you move away from your central field of view. Because of the pixel orientation, the screen may not be viewable as clearly when looking at the screen from an angle, but viewing angles of TFT’s vary depending on the panel technology used.

As a general rule, the viewing angles are IPS-type > VA-type > TN Film. The viewing angles are often over exaggerated in manufacturers specs, especially with TN Film panels where quoted specs of 160 / 160 and even 170 / 170 are based on overly loose measuring techniques. Be wary of 176/176 figures as these are sometimes used as over-exaggerated specs for a TN Film panel and are based on more lapse measurement techniques as well.

In reality, IPS and VA panels are the only technologies which can truly offer wide viewing fields and are commonly quoted as 178/178. VA panels can show a colour / contrast distortion as you move slightly away from a central point. While most people do not notice this anomaly, others find it distracting. They also show more apparent contrast and gamma shifts with changes in the users line of sight. IPS-type panels do not suffer from this and are generally considered the superior technology for wide fields of view.

TFT screens do not refresh in the same way as a CRT screen does, where the image is redrawn at a certain rate. As a TFT is a static image, and each pixel refreshes independently, setting the TFT at a common 60Hz native refresh rate does not cause the same problems as it would on a CRT. There is no cathode ray gun redrawing the image as a whole on a TFT. You will not get flicker, which is the main reason for having a high refresh rate on a CRT in the first place. Standard TFT monitors operate with a 60Hz recommended refresh rate, but can sometimes support up to 75Hz maximum (within the spec) or sometimes even further using ‘overclocking’ methods. The reason that 60Hz is recommended by all the manufacturers is that it is related to the vertical frequency that TFT panels run at. Some more detailed data sheets for the panels themselves clearly show that the operating vertical frequency is between about 56 and 64Hz, and that the panels ‘typically’ run at 60Hz (see the LG.Philips LM230W02 datasheet for instance – page 11). If you decide to run your refresh rate from your graphics card above the recommended 60Hz it will work fine, but the interface chip on the monitor will be in charge of scaling the frequency down to 60Hz anyway. Some screens will allow you to run at the maximum 75Hz as well for an additional boost in frame rates and some minor improvements in motion clarity. The support of this will really depend on the screen, your graphics card and the video connection being used. You may find the screen operates fine at the higher refresh rate setting but in reality the screen will often drop frames to meet the 60Hz recommended setting (or spec of the panel) anyway. Generally we would suggest sticking to 60Hz on standard TFT monitors.

You will see more mention of higher refresh rates from both LCD televisions and now desktop monitors. It’s important to understand the different technologies being used though and what constitutes a ‘real’ 120Hz and what is ‘interpolated’:

Interpolated 120Hz+– These technologies are the ones commonly used in LCD TV’s where TV signal input is limited to 50 / 60 Hz anyway (depending on PAL vs NTSC). To help overcome the issues relating to motion blur on such sets, manufacturers began to introduce a technology to artificially boost the frame rate of the screen. This is done by an internal processing within the hardware which adds an intermediate and interpolated (guessed / calculated) frame between each real frame, boosting from 50 / 60fps to 100 / 120 fps. This technology can offer a noticeable improvement in practice when it is controlled very well. Some sets even have 240 and 480Hz technologies which operate in the same way, but with further interpolation and inserted frames. See here for further information.

Manufacturer specifications will usually list power consumption levels for the monitor which tell you the typical power usage you can expect from their model. This can help give you an idea of running costs, carbon footprint and electricity demands which are particularly important when you’re talking about multiple monitors or a large office environment. Power consumption of an LCD monitor is typically impacted by 3 areas:

This relates to the connection type from the TFT to your PC or other external device. Older screens nearly all came with an analogue connection, commonly referred to as D-sub or VGA. This allows a connection from the VGA port on your graphics card, where the signal being produced from the graphics card is converted from a pure digital to an analogue signal. There are a number of algorithms implemented in TFT’s which have varying effectiveness in improving the image quality over a VGA connection. Some TFT’s with then offer a DVI input as well to allow you to make use of the DVI output from your graphics card which you might have. This will allow a pure digital connection which can sometimes offer an improved image quality. It is possible to get DVI – VGA converters. These will not offer any improvements over a standard analogue connection, as you are still going through a conversion from digital to analogue somewhere along the line. Dual-Link DVI is also sometimes used which is a single DVI connection but with more pins, allowing for higher resolution/refresh rate support than a single-link DVI.

Some screens also offer other interfaces designed for external devices such as games consoles and DVD players. HDMI, S-Video, Composite and Component are available on some models if this functionality is appealing and are widely implemented to allow connection of other external devices. Some of these interfaces are also capable of carrying sound as well as video (e.g. HDMI). With many modern graphics cards also offering HDMI connections, the availability of these on a monitor is very useful.

One of the most important aspects of any display you can understand is the panel technology being used. Specifications alone won’t give you the full picture of a displays performance, and we all know that manufacturers can exaggerate specs on paper to suit their marketing. With an understanding of the panel technology being used you will get a feel for the overall performance characteristics of the display and how it should perform in real terms. Our extensive panel search database helps you identify the panel technology (and manufacturer and part number where known) of many screens in the market. This article which follows will help you understand what the different panel technologies can offer you. A lot of manufacturers now list the panel technology as well in their specs, something which wasn’t included a in the past.

TN Film panels are the mostly widely used in the desktop display market and have been for many years since LCD monitors became mainstream. Smaller sized screens (15″, 17″ and 19″) are almost exclusively limited to this technology in fact and it has also extended into larger screen sizes over the last 7 years or so, now being a popular choice in the 20 – 28″ bracket as well. The TN Film panels are made by many different manufacturers, with the big names all having a share in the market (Samsung, LG.Display, AU Optronics) and being backed up by the other companies including most notably Innolux and Chunghwa Picture Tubes (CPT). You may see different generations of TN Film being discussed, but over the years the performance characteristics have remained similar overall.

TN Film has always been so widely used because it is comparatively cheap to produce panels based on this technology. As such, manufacturers have been able to keep costs of their displays down by using these panels. This is also the primary reason for the technology to be introduced into the larger screen sizes, where the production costs allow manufacturers to drive down retail costs for their screens and compete for new end-users.

The other main reason for using TN Film is that it is fundamentally a responsive technology in terms of pixel latency, something which has always been a key consideration for LCD buyers. It has long been the choice for gaming screens and response times have long been, and still are today, the lowest out of all the technologies overall. Response times typically reach a limit of around 5ms at the ISO quoted black > white > black transition, and as low as 1ms across grey to grey transitions where Response Time Compensation (overdrive) is used. TN Film has also been incorporated into true 120Hz+ refresh rate desktop displays, pairing low response times with high refresh rates for even better moving picture and gaming experiences, improved frame rates and adding 3D stereoscopic content support. Modern 120Hz+ refresh rate screens normally also support NVIDIA 3D Vision 2 and their LightBoost system which brings about another advantage for gaming. You can use the LightBoost strobed backlight system in 2D gaming to greatly reduce the perceived motion blur which is a significant benefit. Some screens even include a native blur reduction mode instead of having to rely on LightBoost ‘hacks’, providing better support for strobing backlights and improving gaming experiences when it comes to perceived motion blur. As a result, TN Film is still the choice for gamer screens because of the low response times and 120Hz+ refresh rate support.

The main problem with TN Film technology is that viewing angles are pretty restrictive, especially vertically, and this is evident by a characteristic severe darkening of the image if you look at the screen from below. Contrast and colour tone shifts can be evident with even a slight movement off-centre, and this is perhaps the main drawback in modern TN Film panels. Some TN Film panels are better than others and there have been improvements over the years to some degree, but they are still far more restrictive with fields of view than other panel technologies. The commonly quoted 170/160 viewing angles are an unfair indication of the actual real-life performance really, especially when you consider the vertical contrast shifts. Where viewing angles are quoted by a manufacturer as 160/160 or 170/160 that is a clear sign that the panel technology will be TN Film incidentally.

Most TN Film panels are produced with a 1920 x 1080 resolution, although some larger sizes have become available with higher resolutions. A new generation of Quad HD 2560 x 1440 27″ TN Film panels emerged in 2014. We’ve also seen the introduction of 28″ Ultra HD 3840 x 2160 resolution TN Film panels become available, and adopted in many of the lower cost “4k” models in the market. Where used, the Anti-Glare (AG) coating used on most TN Film panels is moderately grainy – not as grainy as some older IPS panel coatings, but not as light as modern IPS, VA or equivalents. Also at the time of writing there are no ultra-wide (21:9 aspect ratio) or curved format TN Film panels in production.

VA technology was first developed by Fujitsu in 1996. However the limited viewing angles were its main disadvantage, and so further investment focused on addressing this problem. It was eventually solved by dividing each pixel into domains which worked synchronously. This lead the birth of the following technologies:

MVA technology, was later developed by Fujitsu in 1998 as a compromise between TN Film and IPS technologies. On the one hand, MVA provided a full response time of 25 milliseconds (that was impossible at the time with IPS, and not easily achievable with TN), and on the other hand, MVA matrices had wide viewing angles of 160 – 170 degrees, and thus could better compete with IPS in that parameter. The viewing angles were also good in the vertical field (an area where TN panels suffer a great deal) as well as the horizontal field. MVA technology also provided high contrast ratios and good black depth, which IPS and TN Film couldn’t quite meet at the time.

Premium MVA (P-MVA) panels were produced by AU Optronics, and Super MVA (S-MVA) panels by Chi Mei Optoelectronics (now Innolux) and Fujitsu from 1998 onwards. AU Optronics have since entered a more recent generation referred to as AMVA (see the next section) and S-MVA panels are rarely used in mainstream monitors nowadays. When they were launched they were able to offer improved response times across grey to grey (G2G) transitions which is a great improvement in the MVA market. While responsiveness was still not as fast as TN Film panels using similar RTC technologies, the improvement was obvious and quite drastic. This was really the first time that MVA matrices could be considered for gaming, and arrived at the time when overdrive was being more widely implemented in the market.

While some improvements have been made, the color-reproduction properties of these modern MVA technologies can still be problematic in some situations. Such panels give you vivid and bright colors, but due to the peculiarities of the domain technology many subtle color tones (dark tones often) are lost when you are looking at the screen strictly perpendicularly. When you deflect your line of sight just a little, the colors are all there again. This is a characteristic “VA panel contrast shift” (sometimes referred to as ‘black crush’ due to the loss of detail in dark colours) and some users pick up on this and might find it distracting. Thus, MVA matrices are somewhere between IPS and TN technologies as concerns color rendering and viewing angles. On the one hand, they are better than TN matrices in this respect, but on the other hand the above-described shortcoming prevents them from challenging IPS matrices, especially for colour critical work.

AU Optronics have more recently (around 2005) been working on their latest generation of MVA panel technology, termed ‘Advanced Multi Domain Vertical Alignment’ (AMVA). This is still produced today although a lot of their focus has moved to the similarly named, and not to be confused AHVA (Advanced Hyper Viewing Angle, IPS-type) technology. Compared with older MVA generations, AMVA is designed to offer improved performance including reduced colour washout, and the aim to conquer the significant problem of colour distortion with traditional wide viewing angle technology. This technology creates more domains than conventional multi-domain vertical alignment (MVA) LCD’s and reduces the variation of transmittance in oblique angles. It helps improve colour washout and provides better image quality in oblique angles than conventional VA LCD’s. Also, it has been widely recognized worldwide that AMVA technology is one of the few ways to provide optimized image quality through multiple domains.

AMVA provides an extra-high contrast ratio of greater than 1200:1, reaching 5000:1 in manufacturer specs at the time of writing for desktop monitor panels by optimized colour-resist implementation and a new pixel design and combining the panels with W-LED backlighting units. In practice the contrast ratio is typically nearer to 3000:1 from what we’ve seen, but still far beyond IPS and TN Film matrices. The result is a more comfortable viewing experience for the consumer, even on dimmer images. This is one of the main improvements with modern AMVA panels certainly, and remains way above what competing panel technologies can offer.

AMVA still has some limitations however in practice, still suffering from the off-centre contrast shift you see from VA matrices. Viewing angles are therefore not as wide as IPS technology and the technology is often dismissed for colour critical work as a result. As well as this off-centre contrast shift, the wide viewing angles often show more colour and contrast shift than competing IPS-type panels, although some recent AMVA panel generations have shown improvements here (see BenQ GW2760HS for instance with new “Color Shift-free” technology). Responsiveness is better than older MVA offerings certainly, but remains behind TN Film and IPS/PLS in practice. The Anti-Glare (AG) coating used on most panels is light, and sometimes even appears “semi glossy” and so does not produce a grainy image.

At the time of writing AMVA panels are typically offered with an HD 1920 x 1080 resolution, although some are available in sizes up to 32″ maximum, at a resolution of 2560 x 1440 (Quad HD). At this time there are no native 120Hz+ AMVA panels from AU Optronics in production although at one point AUO were looking into them. Also at the time of writing there are no ultra wide (21:9 aspect ratio) or curved format MVA-type panels in production.

We have included this technology in this section as it is a modern technology still produced by Sharp as opposed to the older generations of MVA discussed above. Sharp are not a major panel manufacturer in the desktop space, but during 2013 began to invest in new and interesting panels using their MVA technology. Of note is their 23.5″ sized MVA panel which was used in the Eizo Foris FG2421 display. This is the first MVA panel to offer a native 120Hz refresh rate, making it an attractive option for gamers. Response times had been boosted significantly on the most part, bringing this MVA technology in line with modern IPS-type panels when it comes to pixel latency. The 120Hz support finally allowed for improved frame rates and motion smoothness from VA technology, helping to rival the wide range of 120Hz+ TN Film panels on the market.

Of particular note also are the excellent contrast ratios of this technology, reaching up to an excellent 5000:1 in practice, not just on paper. Viewing angles are certainly better than TN Film and so overall these MVA panels can offer an attractive all-round option for gaming, without some of the draw-backs of the TN Film panels. Viewing angles are not as wide as IPS panel types and there is still some noticeable gamma shift at wider angles, and the characteristic VA off-centre contrast shift still exists.

The liquid crystals in a PVA matrix have the same structure as in a MVA matrix – domains with varying orientation of the crystals allow keeping the same color, almost irrespective of the user’s line of sight and viewing angle. Viewing angles are not perfect though, as like with MVA matrices when you are looking straight at the screen, the matrix “loses” some shades, which return after you deflect your line of sight from the perpendicular a little. This ‘off-centre’ contrast shift, or ‘black crush’ as it is sometimes called is the reason why some colour enthusiasts prefer IPS-type displays. The overall viewing angles are also not as wide as IPS-type panels, showing more obvious colour and contrast shifts as you change your line or sight.