viewable angles for matrix led backlights tft lcd monitor quotation

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.

When no electric field affects the structure of the crystals, there is a 90 degree twist in the alignment. This twist allows for light to move through the layer, polarizing the light as it passes to then go through the surface polarizer.

If an electric field is applied, the twist in the crystal structure of the molecules can be unwound, straightening them out. When this happens, the light is not polarized and cannot pass through the surface polarizer, displaying a black pixel. It is also possible to create an in between of the fully lit or fully opaque pixel; if the light is partially polarized (the electric field does not fully straighten the crystal alignment), then a middle luminance level of light is emitted from the LED backlights through the polarizer.

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.

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.

LCD is the abbreviation for liquid crystal display. An LCD basically consists of two glass plates with a special liquid between them. The special attribute of this liquid is that it rotates or “twists” the plane of polarized light. This effect is influenced by the creation of an electrical field. The glass plates are thus each coated with a very thin metallic film. To obtain polarized light, you apply a polarization foil, the polarizer, to the bottom glass plate. Another foil must be applied to the bottom glass plate, but this time with a plane of polarization twisted by 90°. This is referred to as the analyzer.

In the idle state, the liquid twists the plane of polarization of the incoming light by 90° so that it can pass the analyzer unhindered. The LCD is thus transparent. If a specific voltage is applied to the metallic film coating, the crystals rotate in the liquid. This twists the plane of polarization of the light by another 90°, for example: The analyzer prevents the light getting through, and the LCD thus becomes opaque.TN, STN, FSTN, blue mode, yellow-green mode

However, the different colors occur only in displays that are either not lit or that are lit with white light. If there is any color in the lighting (e.g. yellow-green LED lighting), it overrides the color of the display. A blue-mode LCD with yellow-green LED lighting will always appear yellow-green.Static or multiplex driving method

Small displays with a small viewing area are generally statically driven. Static displays have the best contrast and the largest possible angle of view. The TN technology fulfills its purpose to the full here (black and white display, reasonably priced). The bigger displays get, however, the more lines become necessary in static operation (e.g. graphics 128x64=8192 segments =8192 lines). Since there is not enough space on either the display or a driver IC for so many lines, multiplexing is used. The display is thus divided up into rows and columns, and there is a segment at each intersection (128+64=192 lines). Scanning takes place row by row (64x, in other words a multiplex rate of 1:64). Because only 1 row is ever active at any one time, however, the contrast and the angle of view suffer the higher the multiplex rate becomes. This makes it essential to use STN.Angle of view 6°°/12°°

Every LCD has a preferred angle of view at which the contrast of the display is at its optimum. Most displays are produced for the 6°° angle of view, which is also known as the bottom view (BV). This angle corresponds to that of a pocket calculator that is lying flat on a desktop.

LCDs without lighting are hard to imagine these days. However, since there are basically four different types of lighting, the type selected depends very much on the application. Here is a brief overview to clarify the situation:LED

Standard LCDs have a temperature range of 0 to +50°C. High-temperature displays are designed for operation in the range from -20 to +70°C. In this case, however, additional supply voltage is generally required. Since the contrast of any LCD is dependent on the temperature, a special temperature-compensation circuit is needed in order to use the entire temperature range, and this is particularly true for high-temperature displays (-20 to +70°C). Manual adjustment is possible but rather impractical for the user.

However, the storage temperature of a display should never be exceeded under any circumstances. An excessively high temperature can destroy the display very quickly. Direct exposure to the sun, for example, can destroy an LCD: This is because an LCD becomes darker (in positive mode) as it gets hotter. As it gets darker, it absorbs more light and converts it to heat. As a result, the display becomes even hotter and darker... In this way, temperatures of over 100°C can quickly be reached.Dot-matrix, graphics and 7-segment displays

The first LCDs were 7-segment displays, and they are still found today in simple pocket calculators and digital watches. 7 segments allow all of the digits from 0 to 9 to be displayed.

Text displays require what is known as a dot matrix, an area consisting of 5x7=35 dots, in order to display all of the letters in the alphabet as well as various special characters. Graphics displays have a similar structure to text displays. In this case, however, there are no spaces between the lines and characters.Display drivers and controllers

The semiconductor industry now offers a very large range of LCD drivers. We generally distinguish between pure display drivers without intelligence of their own, controllers with a display memory and possibly a character set, and micro-controllers with integrated LC drivers.

Pure display drivers work in a similar way to a shift register. They generally have a serial input. They require an external pulse, and in multiplex operation with high frequency they require new display data continuously in order to achieve a refresh frequency that is as high as possible (MSM5219, UPD7225, HD44100, LC7942, etc.). An example of a genuine controller is theHD44780 for dot-matrix displays: Once it has received the ASCII code, the controller manages its character set, memory and multiplexing entirely on its own. The following controllers are widely used for graphics displays: HD61202/3, HD61830, SED1520, SED1330, T6963.

Many ask themselves, "What is the difference between an LCD display and a TFT-display?" or "What is the difference between a TFT and an OLED display?". Here are these 3 sometimes extremely different display technologies briefly explained. LCD vs. TFT vs. OLED (comparison).

- The LCD (Liquid Crystal Display) is a passive display technology. The operation and the structure are described above. Passive means that an LCD can only darken or let out light. So it always depends on ambient light or a backlight. This can be an advantage because the power consumption of a LCD display is very, very low. Sometimes even less than the accumulated power consumption of an E-paper display, which in static operation requires absolutely no energy to maintain the content. To change the contents, however, a relatively large amount of power is required for an E-paper display.

LCDs can also be reflective, so they reflect incident light and are therefore legible even at maximum brightness (sunlight, surgical lighting). Compared to TFT and also OLED, they have an unbeatable advantage in terms of readability and power consumption :; the "formula" is: Sunlight = LCD.

- A TFT-display (of Thin-Film Transistor) is usually a color display (RGB). From the construction and the technology it corresponds to the LCD. It is also passive, so it needs a backlight. This is in any case necessary except for a few, very expensive constructions. However, a TFT needs much more light than the monochrome relatives, because the additional structures on the glass as well as the additional color filters "swallow" light. So TFTs are not particularly energy-efficient, but can display in color and at the same time the resolution is much higher.

- OLED displays (by Organic-Light-Emitting-Diode) are as the name implies active displays - every pixel or sign generates light. This achieves an extremely wide viewing angle and high contrast values. The power consumption is dependent on the display content. Here OLEDs to TFTs and LCDs differ significantly, which have a nearly constant power consumption even with different display contents. Unfortunately, the efficiency of converting the electric current into light energy is still very poor. This means that the power consumption of OLEDs with normal content is sometimes higher than that of a TFT with the same size. Colored OLEDs are increasingly used in consumer devices, but for the industry, due to their availability and lifetime, currently only monochrome displays are suitable (usually in yellow color).

In the reaction time, the OLEDs beat each TFT and LCD by worlds. Trise and Tfall are about 10μs, which would correspond to a theoretical refresh rate of 50,000 Hz. Possibly an advantage in very special applications.

Finally the question "What is better, LCD, OLED or TFT?" Due to the physical differences you can not answer that blanket. Depending on the application, there are pros and cons to each individual technology. In addition to the above differences, there are many more details in the design and construction that need to be individually illuminated for each device. Write us an e-mail or call us: we have specialists with some 20- and 30-year experience. We are happy to compare different displays together with you.AACS and IPS technology

Once more the new AACS technology (All-Angle-Color-Stability) improves the color stability for different viewing angles. It"s providing same color for 90° straight view as for 20° or 160° bottom or top view. There"s no more color shift or inverting effect.

Technology can be confusing because it evolves quickly, and there are complex acronyms for almost everything. If you are thinking ofbuildinga monitor or want to learn about the technology, you will encounter the term TFT Monitor at some point.

A lot goes on behind the glass surface, and we will look at this in comparison to other technologies to paint a clear picture of what TFT is and how it evolved.

TFT is an acronym for Thin Film Transistor, and it is a technology used in Liquid Crystal Display screens. It came about as an improvement to passive-matrix LCDs because it introduced a tiny, separate transistor for each pixel. The result? Such displays could keep up with quick-moving images, which passive-matrix LCDs could not do.

Also, because the transistors are tiny, they have a low power consumption and require a small charge to control each one. Therefore, it is easy to maintain a high refresh rate, resulting in quick image repainting, making a TFT screen the ideal gaming monitor.

The technology improved on the TN (Twisted Nematic) LCD monitor because the shifting pattern of the parallel, horizontal liquid crystals gives wide viewing angles. Therefore, IPS delivers color accuracy and consistency when viewed at different angles.

Both TFT and IPS monitors are active-matrix displays and utilize liquid crystals to paint the images. Technically, the two are intertwined because IPS is a type of TFT LCD. IPS is an improvement of the old TFT model (Twisted Nematic) and was a product of Hitachi displays, which introduced the technology in 1990.

The monitors can create several colors using the different brightness levels and on/off switches. But unlike OLED, both TFT and IPS do not emit light, so most have bright fluorescent lamps or LED backlights to illuminate the picture. Also, neither of them can produce color, so they have an RGB color filter layer.

Easy to Integrate and Update: By combining large-scale semiconductor IC and light source technology, TFTs have the potential for easy integration and updating/development.

Wide Application Range: TFTs are suitable for mobile, desktop screens, and large-screen TVs. Additionally, the technology can operate at a temperature range of -20°C to +50°C, while the temperature-hardened design can remain functional at temperatures not exceeding -80°C.

Impressive Display Effect: TFT displays use flat glass plates that create an effect of flat right angles. Combine this with the ability of LCDs to achieve high resolutions on small screen types, and you get a refreshing display quality.

Good Environmental Protection: The raw materials used to make TFT displays produce zero radiation and scintillation. Thus, the technology does not harm the user or the environment.

Mature Manufacturing Technology: TFT technology came into existence in the 60s. Over time, its manufacturing technology has matured to have a high degree of automation, leading to cheaper, large-scale industrial production.

Wide View Angle: One of the main advantages of IPS screens is their wide viewing angle due to the horizontal liquid crystals. They do not create halo effects, grayscale, or blurriness, but these are common flaws with TFTs.

Better Color Reproduction and Representation: The pixels in TFTs function perpendicularly after activation with the help of electrodes. However, IPS technology makes the pixels function while parallel horizontally. Thus, they reflect light better and create a more original and pristine image color.

Faster Frequency Transmittance: Compared to TFT, IPS screens transmit frequencies at about 25ms, which is 25x faster. This high speed is necessary to achieve wide viewing angles.

Liquid Crystal Display (LCD) is a front panel display that utilizes liquid crystals held between two layers of polarized glass to adjust the amount of blocked light. The technology does not produce light on its own, so it needs fluorescent lamps or white LEDs.

As explained earlier, TFT improved on the passive-matrix LCD design because it introduces a thin film transistor for each pixel. The technology reducescrosstalkbetween the pixels because each one is independent and does not affect the adjacent pixels.

LED screens are like the new kids on the block in the display market, and they operate very differently from LCDs. Instead of blocking light, LEDs emit light and are thinner, provide a faster response rate, and are more energy-efficient.

Since IPS is a type of TFT, when comparing the two, we are essentially looking at the old Thin-Film Transistor technology (Twisted Nematic) vs. the new (IPS). Even though TN is relatively old, this digital display type has its advantages, a vital one being the fast refresh rate. This feature makes such screens the preferred option by competitive gamers. If you have any inquiries about the technology,contact usfor more information.

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.

Make sure your graphics card can support the desired resolution of the screen you are choosing, and based on your uses. If you are a gamer, you may want to consider whether your graphics card can support the resolution and refresh rate you will want to use to power your screen. Also keep in mind whether you are planning to connect external devices and the resolution they are designed to run at. For instance if you have a 16:10 format screen and plan to use an external device which runs at 16:9, you will need to ensure the screen is able to scale the image properly and add black borders, instead of distorting the aspect ratio of the image.

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.

To display this content of this type, your screen needs to be able to 1) handle the full resolution naturally within its native resolution, and 2) be able to handle either the progressive scan or interlaced signal over whatever video interface you are using. If the screen cannot support the full resolution, the image can still be shown but it will be scaled down by the hardware and you won’t be take full advantage of the high resolution content. So for a monitor, if you want to watch 1080 HD content you will need a monitor which can support at least a vertical resolution of 1080 pixels, e.g. a 1920 x 1080 monitor.

In today’s monitor market resolutions are being pushed even higher and we need to start thinking about them in a different way. See the subsequent sections on pixel pitch and PPI for more information on how we should think about resolution now.

This has given rise to modern Ultra HD standards and terms like 4K and 5K. Ultra HD is a term for monitors with a 3840 x 2160 resolution, that being four times the resolution of Full HD 1920 x 1080. Screens with this Ultra HD resolution are often referred to as “4K” as well, although strictly that should only be used for screens with 4092 x 2160 resolution (4K representing the vertical resolution here). There are also some 5K capable monitors produced which offer 5120 x 2880 resolution (5K here representing the vertical resolution). Please see the following sections which talk about Pixel Pitch and PPI and will help you understand these higher resolutions in more detail.

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.

Resolution is typically thought as a factor which determines the screen area or screen “real estate” you will have available. In years gone by as panel sizes increased, resolutions were increased as well and so bigger screens could offer you more desktop space to work with. Split-screen working and high resolution image work become more and more possible. This is fine up to a point, but pushing resolution for the purposes of delivering more desktop real-estate reaches a point where it becomes somewhat impractical for desktop monitors. For instance, a 40″ 3840 x 2160 resolution delivers a comfortable pixel pitch and font size natively (very similar to a 27″ at 2560 x 1440), so if you wanted a higher resolution than this you would have to increase the screen size again probably. You start to reach the point where sitting close to a screen so large becomes impractical.

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.

Of course the problem with this is that if you run a screen as small as 27″ with a 5K resolution, the font size is absolutely tiny by default. You get a massive boost of desktop real-estate, just like when moving from 1920 x 1080 to 2560 x 1440, but that’s not the purpose of these higher resolutions now. To overcome this you need to use the scaling options in your Operating System software to scale the image and make it more usable. Windows provides for instance scaling options like 125% and 150% within the control panel. On a 3840 x 2160 Ultra HD resolution if you use a 150% scaling option for example you will in effect reduce the desktop area by a third, resulting in the same desktop area as a 2560 x 1440 display (i.e. 2560 x 150% = 3840). The OS scaling makes font sizes more comfortable and reasonable, but you maintain the sharp picture quality and small pixel pitch of the higher resolution panel. A 3840 x 2160 res panel scaled at 150% in Windows will look sharper and crisper than a 2560 x 1440 native panel without scaling, despite the fact both would have the same effective desktop area available.

Scaling via your OS is not the same as scaling from your monitor. If you just simply ran the screen at a lower resolution like 2560 x 1440 within the resolution section of your graphics card, the image gets interpolated by the monitor scaler instead. You get the same end result of a 2560 x 1440 sized desktop area size, but the image clarity is lost and you lose a lot of sharpness. The monitor is doing the interpolation for you here. Instead you run the screen at the full 3840 x 2160 resolution in the graphics card settings and allow the OS scaling control to increase font size and make the image useable.

How well the scaling is done really depends on your Operating System and software you are using. Some modern OS like Mac OS and Windows 7 / 8 / 10 handle scaling very well as they are designed to accommodate super high resolutions well. Older OS might struggle and you may find some odd sizing issues in some cases. Some software packages, programs and games also handle scaling in different ways, so it’s something to watch out for. Super high resolutions which require OS scaling might not be for everyone at the moment, but expect to see them become more and more the norm in the future.

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

Response Time is the spec which many people, especially gamers, have come to regard as the most important. In practical terms the spec is designed to refer to the speed of the liquid crystal pixels and how quickly they can change from one colour to another, and therefore how fast the picture can be redrawn. The faster this transition can change, the better, and with more fluid changes the images can change overall a lot faster. This helps reduce the effects of blurring and ghosting in games and movies which can be an issue if response time is too slow. As a general rule of thumb, the lower the response time, the better.

Do not rely entirely on response time specs quoted by manufacturers as a be all and end all to the monitor’s performance. Different manufacturers have different ways of measuring their response time, and one 5ms panel might not be the same in real use to another 5ms panel for instance. Panel technology also plays a part here, and don’t get confused with standard response times and grey to grey (G2G) figures. However, response times can be treated a guide to the performance of the screen, and as a rule of thumb, the lower the better.

The traditional response time standard (ISO response time) is measured as the rise time (tR) and fall time (tF) of a pixel as it changes black > white > black. The total ‘response time’ is quoted as the total of the tR + tF. On older screens users needed to be wary of the figures manufacturers quote, as sometimes the ‘response time’ can be quoted as just the rise time, and not the total response time. This measurement of the black > white > black transition was defined as the ISO standard for response time measurements before the days of ‘overdrive’ being used (discussed in a moment). The reason this particular transition was selected as the response time figure was that it was always the fastest change possible, and manufacturers therefore quoted their best measurement. The reason this was the fastest was because at the time the highest voltage was applied to the pixels to make that change (since it was the most drastic difference from black to white).

On these older panels where overdrive was not being used, in reality the response time of the pixels will vary depending on the colour change they are making. In practice, a full black > white change is not common, and instead the pixel transitions are in shades of grey, and are then passed through the RGB colour filters. The speed of change will depend on the darkness of the transition, and traditionally (before overdrive) the transitions to lighter greys will be faster. Therefore, a manufacturers quoted response time does not necessarily mean that the speed of the pixels is the same for all the transitions. It is always a good idea to see if there are any third party measurements of response time for any given screen before considering how fast a panel really is in practice. Also take into account perceived response time measurements and comparisons between screens as we carry out in our reviews.

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.

As you can see from the graph, the actual response time can vary quite considerably across the whole grey range, with some changes being much slower. This is the reason you cannot always rely on quoted specs to give an accurate representation of a screens actual pixel response performance. The quoted figures from manufacturers should be treated as a rough guide however to a panels response time, as generally there has been some improvements in the overall latency with the changes from 25ms > 16ms > 12ms > 8ms > 5ms panel generations for instance. The shape of the graph is likely to remain quite similar, but overall, the curve will probably be a little lower when comparing an 8ms to a 16ms for instance. Overall it won’t be twice as fast though.

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):

This is again a mock up, but shows a typical curve shape you may expect from a VA / IPS panel (not using overdrive) when compared with TN film. Although a VA/IPS screen might be quoted as perhaps 12ms for instance, this might not mean it is as reactive as a 12ms TN film panel. Again, it is a good idea to check for reviews which measure the response time across the whole range as well as to consider real-life responsiveness tests such as those we carry out in our reviews.

Overdrive or ‘Response Time Compensation’ (RTC) is a technology which is designed to boost the response times of pixels across all transitions, with particular focus on improving the grey to grey changes which is the most important as those transitions are far more common in real-life uses. It is achieved by sending an over-voltage to the pixels to make them change orientation more quickly. While the full black > white change remains largely unchanged (since it already received the maximum voltage anyway), improvements across other transitions are often dramatic. With the introduction of overdriven panels the ISO point is not always the fastest transition any more, and so if a monitor has a response time quoted as “grey to grey / G2G” then you can be pretty certain it is using overdrive technology. The manufacturers still want to quote the fastest response time of their panel and show the improvements they have made though, but be wary of this change away from the ISO standard of quoting response times. The ISO response times have hit a wall really with TN Film stuck at 5 – 8ms, IPS stuck at around 16ms and MVA/PVA stuck at about 12ms. However, with the introduction of overdrive technologies, the more important grey to grey transitions are now significantly improved, and response times of 1 – 5ms G2G are now common place. These technologies have allow significant improvements in all panel technologies, but particularly in IPS and VA panels where response times were previously poor.

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:

Movement isn’t perfectly fluid. Depending on its speed, the car is shown in several successive positions. If the car goes very fast, the positions are very close and the eye perceives a flowing movement. A monitor without ghosting effects would have previous images completely fading away when a new one appears. This is the theory and in practice, it’s often not the case as images fade progressively. Sometimes up to 5 afterglow images remain on the monitor and represent the visible white trail behind objects. Some monitors have strong overdrives in addition to image anticipation algorithms and where these are too aggressively applied, or poorly controlled, it can result in problems. In this case, an image can appear in front or behind the main object, creating a white or dark halo commonly.

We use this software to test the monitors we review, capturing images using a camera and comparing the best case and worst case examples. This gives us a good way to compare screens side by side and evaluate a screens responsiveness in practice. We then combine those visual tests with the more advanced oscilloscope measurements to give a comprehensive understanding of a panels response times and gaming performance.

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.

For these tests we use the Blurbusters.com Ghosting Motion Test which is designed to be used with pursuit camera setups. The pursuit camera method is explained at BlurBusters. We carry out the tests at various refresh rates, with and without any Blur Reduction mode enabled. These UFO objects were moving horizontally at 960 pixels per second, at a frame rate matching refresh rate of the monitor.

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.

On screens with blur reduction backlights it is possible to greatly reduce the perceived motion blur. With these blur reduction features enabled the backlight is strobed briefly, once per refresh, for low persistence.The brief backlight flash prevents tracking-based motion blur and the moving object is far easier to see when tracking it across the screen with your eyes (or by the pursuit camera). Normally these blur reduction modes lead to extremely little leftover ghosting caused by pixel transitions (virtually invisible to the human eye), since nearly all (>99%+) pixel transitions, including overdrive artefacts, are now kept unseen by the human eye, while the backlight is turned off between refreshes.

The clarity of the moving image is improved significantly and tracking across the screen with your eye is much easier and clearer. These kind of tests give you a good visual indication of the improvements which blur reduction backlights can bring in perceived motion blur.

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.

Frame Rate Control / Temporal Dithering– The other method is Frame-Rate-Control (FRC), also referred to sometimes as temporal dithering. This works by combining four colour frames as a sequence in time, resulting in perceived mixture. In basic terms, it involves flashing between two colour tones rapidly to give the impression of a third tone, not normally available in the palette. This allows a total of 16.2 reproducible million colours. Thanks to Frame-Rate-Control, TN panel monitors have come pretty close to matching the colours and image quality of VA or IPS panel technology, but there are a number of FRC algorithms which vary in their effectiveness. Sometimes, a twinkling artefact can be seen, particularly in darker shades, which is a side affect of such technologies. Some TN Film panels are now quoted as being 16.7 million colours, and this is down to new processes allowing these panels to offer a better colour depth compared with older TN panels.

Other panel technologies however can offer more possible pixel orientations and therefore more steps between each shade. VA and IPS panels are traditionally capable of 256 steps for each RGB sub pixel, allowing for a possible 16.7 million colours (true 8-bit, without FRC). These are referred to as 8-bit panels with 24-bit colour (8-bit per sub pixel = 8 + 8 + 8 = 24). While most IPS and VA panels support 8-bit colour, modern IPS and VA panels do sometimes use 6-bit + FRC instead. See this news piece for further information.

10-bit colour depth is typically only used for very high end graphics uses and in professional grade monitors. There are three main ways of implementing 10-bit colour depth support. Most screens which are advertised as having 10-bit support are actually using true 8-bit panels. There is an additional FRC stage added to extend the colour palette. This FRC can be applied either on the panel side (8-bit + FRC panels) or on the monitor LUT/electronics side. Either way, the screen simulates a larger colour depth and does not offer a ‘true’ 10-bit support. You can also only make use of this 10-bit support if you have a full end-to-end 10-bit workflow, including a supporting software, graphics card and operating system. There are a few ‘true’ 10-bit panels available but these are prohibitively expensive and rarely used at the moment. See our panel parts database for more information about different panels.

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.

Experiments at the beginning of the last century into the human eye eventually led to the creation of a system that encompassed all the range of colours our eyes can perceive. Its graphical representation is called a CIE diagram as shown in the image above. All the colours perceived by the eye are within the collared area. The borderline of this area is made up of pure, monochromatic colours. The interior corresponds to non-monochromic colours, up to white which is marked with a white dot. ‘White Colour’ is actually a subjective notion for the eye as we can perceive different colours as white depending on the conditions. The white dot in the CIE diagram is the so-called flat spectrum dot with coordinates of x=y=1/3. Under ordinary conditions, this colour looks very cold, bluish.

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.

Traditional CCFL backlighting offers a gamut pretty much covering the sRGB colour space. However, the sRGB space is a little small to use as a