tft lcd color monitor not coming on brands

one is a hardware fault, the other is a software problem. Although only these two big aspects but involved in the details of the aspect is very much, the following details about the display color abnormal possible reasons and solutions.

Monitor color is not normal, we recommend the first use of the elimination method, as far as possible to eliminate some simple problems. There are many reasons leading to the abnormal display of the display color, such as checking whether the display data line is normal, the display color control panelis not set well, poor contact, or rust of the display wire may lead to such problems.

For this kind of fault a lot of people say that the video card has a hardware fault, some people say that the picture tube was scrapped, and some people say that the driver of the video card was damaged, these views are wrong.

A kinescope-tube failure can cause this problem, but it is not irreparable – minor electric shocks, serious rewound filament power supply windings, and sometimes the visual discharge power supply resistance of a particular electron gun is miswelded or broken or the resistance value is increased.

For the first kind of fault phenomenon, some models only have a certain slight leakage of electricity between the poles, which usually need no maintenance. They only have aninstant color deviation when starting up, which can be normal in a few seconds.

For the contact pole (sometimes only leakage) fault you can only hand it over to professional maintenance personnel for maintenance, its characteristics are usually caused by the protective shutdown. For irregular deviation color fault usually as long as the relevant electron gun visual power supply resistance and peripheral components repair welding can be done.

For the power supply resistance is broken damage caused by the fault phenomenon and contact pole for full screen back sweep wire and very bright color, but it will not lead to a protective shutdown, the solution is very simple – change the same resistance value of the new resistance! Of course, if the resistance value is increased, you also have to do new processing. In the wet season, we also need to take into account the picture tube seat tube oxidation for this reason, although the resulting color deviation fault is not much, but may encounter it.

In addition, there is easier to let people detour the cause of failure – screen dust caused by too much screen white when red! This kind of fault often happens in the monitor that color temperature slants warm (a lot of monitors can set color temperature by oneself), say so, encounter white (and similar color) slants red when the fault you had better be cleaned the first screen later undertake other checks, if the fault disappears, mean you won’t because of this and “unlucky” detour. Of course, too low brightness values on some models can also cause this “fault” phenomenon.

If all of the above methods are ineffective and the display is well over five years old, we can consider the color deviation of the display caused by the aging of the electron gun to be abnormal.

Some half professionals see the two faults as a tube in life, some of the maintenance personnel to see will say adjust the contrast and the focusing extremely potentiometer and accelerate the potentiometer on the ignition coil will be good, others say it’s caused by a hardware failure or graphics driver damage of graphics, these point of failure judgment is wrong.

The aging of the kinescope and the decline, in contrast, will not cause such failure phenomenon, as for the adjustment of the collector and the acceleration of the electrode potentiometer is not correct, this is palliative, and it is difficult to adjust to a satisfactory degree, the most troublesome is that the fault will soon return, even accelerate the aging of the kinescope.

Usually use more than 2 years of the color display will appear this kind of fault, the real cause of the fault is mostly caused by the picture tube seat moisture oxidation, as long as the replacement of the original new tube seat can be troubleshoot. But some say it would be gilding the gilt by using a small piece of sandpaper to polish the protruding end of the tube to remove the oxide. In the picture tube that the author has replaced the tube seat, some of them do have some oxides on the tube foot, but these oxides are missing from the original tube seat to the tube foot, which can be removed with a brush. Up to now, the author did not see the tube was oxidized, but due to excessive force and make the tube leakage and damage the picture tube is encountered a few cases, so we do not use sandpaper to burnish, so as not to appear “death” damage!

If the replacement of the tube seat is not effective will replace the FBT, but in this work, the author suggests you had better find professional personnel! In addition, some types of visual amplifier parts of the circuit are more special, sometimes after the fault will also cause the image blur. But at this time usually the brightness and line, field amplitude are also abnormal, for this kind of fault point the author recommends that you deliver professional personnel to deal with! If the color display is not a brand-name product and the use of a very long time, then the author suggests that you find a professional electrical maintenance department to replace the work of the tube seat, so as to avoid the occurrence of pipe neck leakage and other accidents after the responsibility!

1) the image is clear at the beginning of starting up, but the color of the display is abnormal as the use time is prolonged and the display becomes increasingly blurred;

2) the image occasionally becomes blurry in use, but it can return to normal soon. However, it becomes more serious and frequent after several days or months of use.

Some people think that this kind of fault is the problem of the line circuit of the monitor — it may be the poor thermal stability of the line tube, the reverse diode, reverse capacitor, and other components or the result of virtual welding. This is completely wrong because none of these components can affect the clarity of the image.

The real failure point of the type 1 fault phenomenon is usually due to the aging of the focusing knob of the FBT. You can try to replace an FBT first. Of course, if the monitor has been in use for more than six years, then we need to take into account the possibility of tube aging. In addition, it may be the tube seat of the picture tube and the large area of the negative copper foil leakage phenomenon caused by the displacer (after analysis like design problems), so sometimes into a maintenance dilemma after the replacement of a genuine tube seat try.

The type 2 fault phenomenon, is usually caused by the poor quality of the picture tube holder. You can solve the problem by replacing it with a new one.

A lot of people think this is the mains voltage of the mains electricity is the insufficient or unstable cause, some “master” can say even because of the lamps and lanterns that contains electronic ballast or electromechanical kind electric appliance brings color to show the interference of power source, somebody says the hardware fault that the video card produced is caused by. In fact, these views are wrong, because the display voltage requirements are not very strict – most of the current color display can be in the 100V ~ 240V power supply voltage under normal operation. As for other electrical appliances that will cause interference is even more impossible, after all, color display use is not mutual inductance stabilized voltage power supply, and other electrical appliances even if the interference will not be screen flicker!

The real fault causes of the first two kinds of faults are usually caused by the virtual welding of some components in the line circuit or the reduction of the +300V filter capacitance at the power supply. The latter possibility is not very high – only in a few models and its more serious loss of volume will cause the human eye to distinguish the flicker. In addition, the circuit of the visual amplifier power supply part of some models is special, and sometimes a component of this part may also cause this fault. Of course, if you set your monitor’s resolution and refresh rate too high or too low, you can set the resolution and refresh rate to the middle value.

There is also a video card or monitor driver there are bugs, so you should first update the driver to try. If the above treatment is not effective, you can focus on checking whether the accelerator voltage and high voltage generated by the FBT are normal, because sometimes these two abnormal voltages can also cause such a phenomenon.

The poor contact of the video card usually causes the failure of starting up and there is an alarm sound or the system is unstable resulting in a crash and other failures. The reason for the poor contact of the graphics card is that the gold finger of the graphics card is oxidized, dust, the quality of the graphics card is poor or the baffle of the case has a problem. For the golden finger oxidation caused by poor contact, can use an eraser to wipe the golden finger to solve; For dust caused by poor contact, general removal of dust can be solved; For the hardware quality caused by poor contact, usually through the replacement method to detect, generally replace the video card to solve; For the case baffle problem caused by poor contact, usually the video card can not be fully inserted into the video card slot, can be replaced by the case to eliminate.

Compatibility failure will usually cause the computer can not to start up and alarm sound, the system is not stable crash or screen abnormal miscellaneous phenomenon. Display card compatibility fault generally occurs in the computer just installed or upgrade, more in the motherboard and display card is not compatible or motherboard slot and display card gold finger can not completely contact. The video card compatibility fault usually USES the replacement method to detect, generally USES the replacement video card to troubleshoot the fault.

The failure of the components of the graphics card will usually cause the failure of the computer can not startup, the system is not stable crash, flower screen, and other fault phenomena. The damage of graphics components generally includes the damage of graphics chip, BIOS, memory, capacitance, or field-effect tube. For the damage and failure of graphics card components, it is generally necessary to carefully measure the signals in the graphics card circuit to judge the damaged components. After finding the damaged components, replace them.

Due to the graphics chip will produce a lot of heat when working, so need to have a better cooling condition, if the cooling fan damage will lead to graphics card overheating can not work normally. The overheat fault of the graphics card usually causes the system unstable crash, flower screen, and other fault phenomena. Video card overheating as long as the replacement of the cooling fan.

The failure of the graphics driver usually causes the system unstable crash, flower screen, text image graphics card is not complete, and other fault phenomena. The video driver’s fault mainly includes the loss of the video driver, the video driver is incompatible with the system, the video driver is damaged, and the video driver cannot be installed. For the video card, driver failure generally first enter the “device manager” to see whether there is a video card driver, if not, re-install. If so, but the graphics driver has a “!”, the video card driver is not installed, the driver version is not correct, the driver and the system are not compatible. Generally, remove the video card driver reinstall, if installed after there are “!”, you can download the new version of the driver installation. If you cannot install a graphics driver, there is usually a problem with the driver or with the registry.

CMOS setup failure is caused by the error of displaying related options in CMOS. Common CMOS setup failures mainly include: integrated graphics card motherboard, CMOS graphics card shielding options setting error; For example, the “AGP Driving Control” option is incorrectly set (usually “AUTO”), “AGP Aperture Size” option is incorrectly set, and “FAST Write Supported” option is incorrectly set.CMOS error is generally modified by loading the default BIOS value.

If the fault is serious, the maintenance requires that you must have certain hands-on ability and professional knowledge, so the author suggests that if you still have not been repaired after eliminating the simple cause of the fault, please deliver it to the electrical maintenance department for treatment. Sometimes some magnetic objects (such as some low power box or ADSL cat power supply, etc.) placed near the display will cause a certain Angle flicker on the screen, so when this phenomenon to try to clear the display around the objects to see, usually the problem can be solved.

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A monitor is connected to the computer but does not display anything. Use the steps in this document to resolve this issue or to determine if the monitor is defective.

With the monitor plugged in, press the power button on the monitor. There should be a power indicator light located on the monitor case. What happens to the light?

If power light remains off when you press the power button, either the monitor is not receiving power or the monitor is defective. Check all of the following items before attempting to service or replace the monitor:

If a message appears on the monitor, the display panel is working and the problem is related to the video signal. For further troubleshooting steps, see Message about No Signal, Signal out of Range, Sleep, or Power Save.

Check for bent or broken connector pins or broken pins that have become lodged inside the holes of the video connector on the computer. With the monitor and computer off, straighten bent pins with a small metal tube, like the tip of an empty mechanical pencil or the tip of a retracted pen. If any of the pins have broken off from the cable and are stuck in the small holes of the video connector (on the computer), remove the broken pins using a metal sewing pin (or similar metal pin that is thin and has a point).

Connect another video cable to the computer and monitor. If possible use a different cable. For example, if your monitor has an HDMI connector and a DVI connector, use the other cable type if possible. If not, use a new cable of the same type.

If the monitor remains blank, connect the monitor to another computer using a different cable to determine if the monitor is bad. Skip to the Step connect the monitor to another computer.

Find the native display resolution for your monitor in the User Manual or in the product specifications for the monitor model. If you are unable to find the native display resolution for your monitor model, temporarily use 1024x768 for troubleshooting purposes.

If you are satisfied with the new display settings, click Yes on the Monitor Settings windows. If you are not satisfied or if the screen just goes black, wait: Windows sets the screen back to the way it was before. Try another setting until you find a display configuration that is compatible with the monitor and meets your needs.

If the native resolution is not available, download and install updated video driver software for your computer. Updating the video driver software can add more resolutions (graphics modes).

If the monitor works, the video hardware on the original computer is likely to be the source of the problems. You can try connecting the original computer to another monitor that works to update its video drivers.

Let us start with the basics first; refresh the knowledge about TN and LCD displays in general, later we will talk about TFTs (Thin Film Transistors), how they differ from regular monochrome LCD displays. Then we will go on to the ghosting effect, so we will not only discuss the technology behind the construction of the TFT, but also some phenomena, like the ghosting effect, or grayscale inversion, that are important to understand when using an LCD TFT display.

Next, we will look at different technologies of the TFT LCD displays like TN, IPS, VA, and of course about transmissive and transflective LCD displays, because TFT displays also can be transmissive and transflective. In the last part we will talk about backlight.

Let us start with a short review of the most basic liquid crystal cell, which is the TN (twisted nematic) display. On the picture above, we can see that the light can be transmit through the cell or blocked by the liquid crystal cell using voltage. If you want to learn more about monochrome LCD displays and the basics of LCD displays, follow this link.

What is a TFT LCD display and how it is different from a monochrome LCD display? TFT is called an active display. Active, means we have one or more transistors in every cell, in every pixel and in every subpixel. TFT stands for Thin Film Transistor, transistors that are very small and very thin and are built into the pixel, so they are not somewhere outside in a controller, but they are in the pixel itself. For example, in a 55-inch TV set, the TFT display contains millions of transistors in the pixels. We do not see them, because they are very small and hidden, if we zoom in, however, we can see them in every corner of each pixel, like on the picture below.

On the picture above we can see subpixels, that are basic RGB (Red, Green, Blue) colors and a black part, with the transistors and electronic circuits. We just need to know that we have pixels, and subpixels, and each subpixel has transistors. This makes the display active, and thus is called  the TFT display. TFT displays are usually color displays, but there are also monochrome TFT displays, that are active, and have transistors, but have no colors. The colors in the TFT LCD display are typically added by color filters on each subpixel. Usually the filters are RGB, but we also have RGBW (Red, Green, Blue, White) LCD displays with added subpixels without the filter (White) to make the display brighter.

What is interesting, the white part of the RGB and RGBW screen will look exactly the same from a distance, because the lights are mixed and generate white light, but when we come closer to the screen, we will not see white light at all.

Going a little bit deeper, into the TFT cell, there is a part inside well known to us from the monochrome LCD display Riverdi University lecture. We have a cell, liquid crystal, polarizers, an ITO (Indium Tin Oxide) layer for the electrodes, and additionally an electronic circuit. Usually, the electronic circuit consists of one transistor and some capacitors to sustain the pixel state when we switch the pixel OFF and ON. In a TFT LCD display the pixels are much more complicated because apart from building the liquid crystal part, we also need to build an electronic part.

That is why TFT LCD display technologies are very expensive to manufacture. If you are familiar with electronics, you know that the transistor is a kind of switch, and it allows us to switch the pixel ON and OFF. Because it is built into the pixel itself, it can be done very quickly and be very well controlled. We can control the exact state of every pixel not only the ON and OFF states, but also all the states in between. We can switch the light of the cells ON and OFF in several steps. Usually for TFT LCD displays it will be 8-bit steps per color, so we have 256 steps of brightness for every color, and every subpixel. Because we have three subpixels, we have a 24-bit color range, that means over 16 million combinations, we can, at least theoretically, show on our TFT LCD display over 16 million distinct colors using RGB pixels.

Now that we know how the TFT LCD display works, we can now learn some practical things one of which is LCD TFT ghosting. We know how the image is created, but what happens when we have the image on the screen for a prolonged time, and how to prevent it. In LCD displays we have something called LCD ghosting. We do not see it very often, but in some displays this phenomenon still exists.

If some elements of the picture i.e., your company logo is in the same place of the screen for a long period of time, for couple of weeks, months or a year, the crystals will memorize the state and later, when we change the image, we may see some ghosting of those elements. It really depends on many conditions like temperature and even the screen image that we display on the screen for longer periods of time. When you build your application, you can use some techniques to avoid it, like very rapid contrast change and of course to avoid the positioning the same image in the same position for a longer time.

You may have seen this phenomenon already as it is common in every display technology, and even companies like Apple put information on their websites, that users may encounter this phenomenon and how to fix it. It is called image ghosting or image persistence, and even Retina displays are not free of it.

Another issue present in TFT displays, especially TN LCD displays, is grayscale inversion. This is a phenomenon that changes the colors of the screen according to the viewing angle, and it is only one-sided. When buying a TFT LCD display, first we need to check what kind of technology it is. If it is an IPS display, like the Riverdi IPS display line, then we do not need to worry about the grayscale inversion because all the viewing angles will be the same and all of them will be very high, like 80, 85, or 89 degrees. But if you buy a more common or older display technology type, like the TN (twisted nematic) display, you need to think where it will be used, because one viewing angle will be out. It may be sometimes confusing, and you need to be careful as most factories define viewing direction of the screen and mistake this with the greyscale inversion side.

On the picture above, you can see further explanation of the grayscale inversion from Wikipedia. It says that some early panels and also nowadays TN displays, have grayscale inversion not necessary up-down, but it can be any angle, you need to check in the datasheet. The reason technologies like IPS (In-Plane Switching), used in the latest Riverdi displays, or VA, were developed, was to avoid this phenomenon. Also, we do not want to brag, but the Wikipedia definition references our website.

We know already that TN (twisted nematic) displays, suffer from grayscale inversion, which means the display has one viewing side, where the image color suddenly changes. It is tricky, and you need to be careful. On the picture above there is a part of the LCD TFT specification of a TN (twisted nematic) display, that has grayscale inversion, and if we go to this table, we can see the viewing angles. They are defined at 70, 70, 60 and 70 degrees, that is the maximum viewing angle, at which the user can see the image. Normally we may think that 70 degrees is better, so we will choose left and right side to be 70 degrees, and then up and down, and if we do not know the grayscale inversion phenomena, we may put our user on the bottom side which is also 70 degrees. The viewing direction will be then like a 6 o’clock direction, so we call it a 6 o’clock display. But you need to be careful! Looking at the specification, we can see that this display was defined as a 12 o’clock display, so it is best for it to be seen from a 12 o’clock direction. But we can find that the 12 o’clock has a lower viewing angle – 60 degrees. What does it mean? It means that on this side there will be no grayscale inversion. If we go to 40, 50, 60 degrees and even a little bit more, probably we will still see the image properly. Maybe with lower contrast, but the colors will not change. If we go from the bottom, from a 6 o’clock direction where we have the grayscale inversion, after 70 degrees or lower we will see a sudden color change, and of course this is something we want to avoid.

To summarize, when you buy older technology like TN and displays, which are still very popular, and Riverdi is selling them as well, you need to be careful where you put your display. If it is a handheld device, you will see the display from the bottom, but if you put it on a wall, you will see the display from the top, so you need to define it during the design phase, because later it is usually impossible or expensive to change the direction.

We will talk now about the other TFT technologies, that allow us to have wider viewing angles and more vivid colors. The most basic technology for monochrome and TFT LCD displays is twisted nematic (TN). As we already know, this kind of displays have a problem with grayscale inversion. On one side we have a higher retardation and will not get a clear image. That is why we have other technologies like VA (Vertical Alignment), where the liquid crystal is differently organized, and another variation of the TFT technology – IPS which is In-Plane Switching. The VA and IPS LCD displays do not have a problem with the viewing angles, you can see a clear image from all sides.

Nowadays all TV sets, tablets and of course mobile phones are IPS or VA. You can turn them around and see the image clear from all sides. But, for monitor applications the TN technology is still widely used, because the monitor usually is in front of you and most of the time you look directly at it, from top, left or right side, but very rarely from the bottom, so the grayscale inversion viewing angle can be placed there. This technology still is very practical because it is affordable and has some advantages for gamers because it is very fast.

Apart from the different organization of the liquid crystals, we also organize subpixels a little bit differently in a VA and IPS LCD displays. When we look closer at the TN display, we will just see the subpixels with color filters. If we look at the VA or IPS display they will have subpixels of subpixels. The subpixels are divided into smaller parts. In this way we can achieve even wider viewing angles and better colors for the user, but of course, it is more complicated and more expensive to do.

The picture above presents the TN display and grayscale inversion. For IPS or VA technology there is no such effect. The picture will be the same from all the sides we look so these technologies are popular where we need wide viewing angles, and TN is popular where we don’t need that, like in monitors. Other advantages of IPS LCD displays are they give accurate colors, and wide viewing angles. What is also important in practice, in our projects, is that the IPS LCD displays are less susceptible to mechanical force. When we apply mechanical force to the screen, and have an optically bonded touch screen, we push the display as well as squeeze the cells. When we have a TN display, every push on the cell changes the image suddenly, with the IPS LCD displays with in-plane switching, different liquid crystals organization, this effect is lesser. It is not completely removed but it is much less distinct. That is another reason IPS displays are very popular for smartphones, tablets, when we have the touchscreens usually optically bonded.

If we wanted to talk about disadvantages, there is a question mark over it, as some of them may be true, some of them do not rely on real cases, what kind of display, what kind of technology is it. Sometimes the IPS displays can have higher power consumption than others, in many cases however, not. They can be more expensive, but not necessarily. The new IPS panels can cost like TN panels, but IPS panels definitely have a longer response time. Again, it is not a rule, you can make IPS panels that are very fast, faster than TN panels, but if you want the fastest possible display, probably the TN panel will be the fastest. That is why the TN technology is still popular on the gaming market. Of course, you can find a lot of discussions on the internet, which technology is better, but it really depends on what you want to achieve.

Now, let us look at the backlight types. As we see here, on the picture above, we have four distinct types of backlight possible. The most common, 95 or 99 per cent of the TFT LCD displays on the market are the transmissive LCD display type, where we need the backlight from the back. If you remember from our Monochrome LCD Displays lecture, for transmissive LCD displays you need the backlight to be always on. If you switch the backlight off, you will not see anything. The same as for monochrome LCD displays, but less popular for TFT displays, we have the transflective LCD display type. They are not popular because usually for transflective TFT displays, the colors lack in brightness, and the displays are not very practical to use. You can see the screen, but the application is limited. Some transflective LCD displays are used by military, in applications where power consumption is paramount; where you can switch the backlight off and you agree to have lower image quality but still see the image. Power consumption and saving energy is most important in some kind of applications and you can use transflective LCD displays there. The reflective type of LCD displays are almost never used in TFT. There is one technology called Low Power Reflective Displays (LPRD) that is used in TFT but it is not popular. Lastly, we have a variation of reflective displays with frontlight, where we add frontlight to the reflective display and have the image even without external light.

Just a few words about Low Power Reflective Displays (LPRD). This kind of display uses environmental light, ambient light to reflect, and produce some colors. The colors are not perfect, not perfectly clear, but this technology is becoming increasingly popular because it allows to have color displays in battery powered applications. For example, a smartwatch would be a case for that technology, or an electrical bike or scooter, where we can not only have a standard monochrome LCD display but also a TFT LCD color display without the backlight; we can see the image even in

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strong sunlight and not need backlight at all. So, this kind of TFL LCD display technology is getting more and more popular when we have outdoor LCD displays and need a low power consumption.

On the picture above, we have some examples of how transmissive and reflective LCD displays work in the sunlight. If we have a simple image, like a black and white pattern, then on a transmissive LCD display, even with 1000 candela brightness, the image probably will be lower quality than for a reflective LCD display; if we have sunlight, we have very strong light reflections on the surface of the screen. We have talked about contrast in more detail in the lecture Sunlight Readable Displays. So, reflective LCD displays are a better solution for outdoor applications than transmissive LCD displays, where you need a really strong backlight, 1000 candela or more, to be really seen outdoors.

To show you how the backlight of LCD displays is built, we took the picture above. You can see the edge backlight there, where we have LEDs here on the small PCB on the edge, and we have a diffuser that distributes the light to the whole surface of LCD screen.

In addition to the backlight, we have something that is called a frontlight. It is similar to backlight, it also uses the LEDs to put the light into it, but the frontlight needs to be transparent as we have the display behind. On the example on the picture above we can see an e-paper display. The e-paper display is also a TFT display variation, but it is not LCD (liquid crystal), it is a different technology, but the back of the display is the same and it is reflective. The example you see is the Kindle 4 eBook reader. It uses an e-paper display and a frontlight as well, so you can read eBooks even during the night.

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Poorly designed backlight. LED-backlit LCD monitors require a backlight to show the image on the screen. The position and quality of these backlight systems have an impact on the uniformity of the screen. Many monitors only have a strip of LEDs at the top or bottom of the screen and use a series of diffusion films behind the LCD panel to create an even backlight. Unfortunately, not all of these designs are made the same, and edge-type backlights will often have a visible backlight that looks like a distracting bright strip on one of the edges of the screen. However, some higher-end monitors have direct LED backlighting with LEDs placed all over the screen, resulting in better uniformity. Learn more about different types of backlights on TVs here.

Lenient manufacturing and uneven frames. LCD screens are made of many layers, and most of these are flexible. When the monitor is being built or transported, some of these layers likely bend. These can cause uneven diffusion of light which leads to clouding and backlight bleed.

Uneven intensity of the lighting. Sometimes, the LEDs themselves have manufacturing issues. This leads to certain areas of the screen having stronger backlight than others which leads to very visible uniformity issues in blacks but also colors and greys.

Monitors use different panel technologies to produce an image. Most monitors use LCD panels, of which there are different types. VA panels are known for their high contrast ratio, so they display deep blacks, but it doesn"t mean they have good black uniformity, as seen with the AOC CQ27G2 in the When It Matters section. The more common IPS panels have a low contrast ratio, which we can see with the ASUS TUF Gaming VG27AQL1A above. On average, VA and IPS panels have about the same black uniformity, but it depends on the model. There"s also a rare third panel type, the TN panel. It usually has the worse uniformity, as you can see here.

There"s another panel technology that"s different from LED-backlit monitors: OLED. These types of displays don"t have a backlight and use self-emitting pixels to display an image. Because of this, they have perfect black uniformity with no blooming around bright objects as they can turn off individual pixels. These monitors get a perfect score of ten for our black uniformity, but there are only a handful of OLED monitors we"ve tested, as they"re more common with TVs. Below you can see what an OLED looks like compared to an LED monitor.

IPS glow refers to a specific type of uniformity issue that, as the name suggests, is most common with IPS-type LCD monitors. Unlike normal uniformity issues, the cause for IPS glow is mostly the screen"s vertical viewing angle, which is why it often appears at the corners.

In a normal viewing position with your eyes being level with the center of the screen, the corners of your monitor are at a much steeper angle than the central areas. These areas of the screen can start to show the artifacts that appear when using your monitor beyond its viewing angle. Colors and brightness shift, and parts of the screen with very slight backlight bleed appear to worsen.

Unfortunately, you can"t do much to mitigate IPS glow except adjust your viewing position. The way to make sure the IPS glow is caused by the vertical viewing angles and not backlight bleed is by shifting your point of view. As you go up and down the screen, if you notice the edges further away from your eyes start to shift color, then this is the IPS glow.

The easiest way to reduce the appearance of uniformity issues is by sitting directly in front of your monitor; sitting off-axis tends to worsen the effects significantly. Otherwise, there"s no other real way to improve the black uniformity unless you want to return the monitor. There are ways to enhance it slightly, but you can rarely solve more problematic cases with these techniques. Uniformity will change across every monitor, so it"s worth trying out multiple units of the same model. If the problem persists, it"s likely that this model, in particular, can be problematic.

You can sometimes reduce backlight bleed caused by the outside frame of your monitor sitting unevenly. If your monitor has rear-accessible screws to disassemble the frame, you can try tightening or loosening them. It can have a very strong impact, so be careful with your adjustments, as it also can make the issue worse.

If you have minor clouding, you can also try a common technique that occasionally helps. With the monitor on and displaying either a black frame or our test pattern, look for the brighter areas of the screen. Using a soft cloth, gently massage the brighter spots. It might take a while, but it can be effective. Make sure to be quite gentle, though, as pressing too hard can damage your monitor.

If you often use your screen in the dark, ambient lighting behind your screen can greatly reduce the visibility of uniformity issues and greatly enhance perceived contrast.

As your monitor heats up and gets used for the first few weeks, it can get better as internal parts settle in properly. Sometimes, just a little time can help parts that were moved in shipping get placed properly. This is also why we display a warm-up video on our monitors before testing them so that the pixels aren"t "cold".

Our black uniformity tests are different from the gray uniformity tests because we see how well the monitor displays a bright object on a dark screen. The gray uniformity tests are for displaying a single color across the screen. You can learn more about them here.

We test for the black uniformity on a monitor to see how well it displays a bright object on a dark screen. This test is important if you tend to use your monitor in a dark environment, especially when viewing content with dark scenes, like video games or movies. A monitor with bad black uniformity can get distracting. We take a photo and measure the standard deviation of the black uniformity, both with the local dimming feature enabled and disabled. A monitor"s panel technology impacts the black uniformity, but it varies between units, so no two monitors are alike.

A more intuitive way to configure monitor settings. Simply drag and drop the Dell Display Manager UI menu from one monitor to another. Allows users to control and change monitor settings easily in a multimonitor configuration.

More customization options to view data based on individual preferences. Users can now customize up to 48 max zones easily and assign them accordingly.

Viewing and using Dell Display Manager (DDM) in portrait mode is now possible. Dell Display Manager (DDM) Easy Arrange templates automatically switch to portrait mode when monitor orientation is pivoted vertically.

KVM Wizard to simplify the KVM setup. Follow step-by-step pop-up windows guide at the click of the KVM Wizard icon on the Dell Display Manager (DDM) user interface. (available on select Dell monitors with KVM capability only.)

IT managers can issue specific instructions using command lines to Dell Display Manager (DDM) to perform tasks within specific times to individual monitor or an entire fleet

Remote Control capabilities (includes Power on/off, restoring factory defaults, changing monitor front of screen settings, optimal resolution, display modes, disabling OSD menu access, input switching).

Up to 38 layouts: With Dell Display Manager’s Easy Arrange, you can organize multiple applications on your screen and snap them into a template of your choice, making multitasking easy and effortless.

User can assign names to each input and define a shortcut key for quick and easy access to multiple connected devices - useful for programmers and gamers.

Glass substrate with ITO electrodes. The shapes of these electrodes will determine the shapes that will appear when the LCD is switched ON. Vertical ridges etched on the surface are smooth.

A liquid-crystal display (LCD) is a flat-panel display or other electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizers. Liquid crystals do not emit light directly,backlight or reflector to produce images in color or monochrome.seven-segment displays, as in a digital clock, are all good examples of devices with these displays. They use the same basic technology, except that arbitrary images are made from a matrix of small pixels, while other displays have larger elements. LCDs can either be normally on (positive) or off (negative), depending on the polarizer arrangement. For example, a character positive LCD with a backlight will have black lettering on a background that is the color of the backlight, and a character negative LCD will have a black background with the letters being of the same color as the backlight. Optical filters are added to white on blue LCDs to give them their characteristic appearance.

LCDs are used in a wide range of applications, including LCD televisions, computer monitors, instrument panels, aircraft cockpit displays, and indoor and outdoor signage. Small LCD screens are common in LCD projectors and portable consumer devices such as digital cameras, watches, digital clocks, calculators, and mobile telephones, including smartphones. LCD screens are also used on consumer electronics products such as DVD players, video game devices and clocks. LCD screens have replaced heavy, bulky cathode-ray tube (CRT) displays in nearly all applications. LCD screens are available in a wider range of screen sizes than CRT and plasma displays, with LCD screens available in sizes ranging from tiny digital watches to very large television receivers. LCDs are slowly being replaced by OLEDs, which can be easily made into different shapes, and have a lower response time, wider color gamut, virtually infinite color contrast and viewing angles, lower weight for a given display size and a slimmer profile (because OLEDs use a single glass or plastic panel whereas LCDs use two glass panels; the thickness of the panels increases with size but the increase is more noticeable on LCDs) and potentially lower power consumption (as the display is only "on" where needed and there is no backlight). OLEDs, however, are more expensive for a given display size due to the very expensive electroluminescent materials or phosphors that they use. Also due to the use of phosphors, OLEDs suffer from screen burn-in and there is currently no way to recycle OLED displays, whereas LCD panels can be recycled, although the technology required to recycle LCDs is not yet widespread. Attempts to maintain the competitiveness of LCDs are quantum dot displays, marketed as SUHD, QLED or Triluminos, which are displays with blue LED backlighting and a Quantum-dot enhancement film (QDEF) that converts part of the blue light into red and green, offering similar performance to an OLED display at a lower price, but the quantum dot layer that gives these displays their characteristics can not yet be recycled.

Since LCD screens do not use phosphors, they rarely suffer image burn-in when a static image is displayed on a screen for a long time, e.g., the table frame for an airline flight schedule on an indoor sign. LCDs are, however, susceptible to image persistence.battery-powered electronic equipment more efficiently than a CRT can be. By 2008, annual sales of televisions with LCD screens exceeded sales of CRT units worldwide, and the CRT became obsolete for most purposes.

Each pixel of an LCD typically consists of a layer of molecules aligned between two transparent electrodes, often made of Indium-Tin oxide (ITO) and two polarizing filters (parallel and perpendicular polarizers), the axes of transmission of which are (in most of the cases) perpendicular to each other. Without the liquid crystal between the polarizing filters, light passing through the first filter would be blocked by the second (crossed) polarizer. Before an electric field is applied, the orientation of the liquid-crystal molecules is determined by the alignment at the surfaces of electrodes. In a twisted nematic (TN) device, the surface alignment directions at the two electrodes are perpendicular to each other, and so the molecules arrange themselves in a helical structure, or twist. This induces the rotation of the polarization of the incident light, and the device appears gray. If the applied voltage is large enough, the liquid crystal molecules in the center of the layer are almost completely untwisted and the polarization of the incident light is not rotated as it passes through the liquid crystal layer. This light will then be mainly polarized perpendicular to the second filter, and thus be blocked and the pixel will appear black. By controlling the voltage applied across the liquid crystal layer in each pixel, light can be allowed to pass through in varying amounts thus constituting different levels of gray.

The chemical formula of the liquid crystals used in LCDs may vary. Formulas may be patented.Sharp Corporation. The patent that covered that specific mixture expired.

Most color LCD systems use the same technique, with color filters used to generate red, green, and blue subpixels. The LCD color filters are made with a photolithography process on large glass sheets that are later glued with other glass sheets containing a TFT array, spacers and liquid crystal, creating several color LCDs that are then cut from one another and laminated with polarizer sheets. Red, green, blue and black photoresists (resists) are used. All resists contain a finely ground powdered pigment, with particles being just 40 nanometers across. The black resist is the first to be applied; this will create a black grid (known in the industry as a black matrix) that will separate red, green and blue subpixels from one another, increasing contrast ratios and preventing light from leaking from one subpixel onto other surrounding subpixels.Super-twisted nematic LCD, where the variable twist between tighter-spaced plates causes a varying double refraction birefringence, thus changing the hue.

LCD in a Texas Instruments calculator with top polarizer removed from device and placed on top, such that the top and bottom polarizers are perpendicular. As a result, the colors are inverted.

The optical effect of a TN device in the voltage-on state is far less dependent on variations in the device thickness than that in the voltage-off state. Because of this, TN displays with low information content and no backlighting are usually operated between crossed polarizers such that they appear bright with no voltage (the eye is much more sensitive to variations in the dark state than the bright state). As most of 2010-era LCDs are used in television sets, monitors and smartphones, they have high-resolution matrix arrays of pixels to display arbitrary images using backlighting with a dark background. When no image is displayed, different arrangements are used. For this purpose, TN LCDs are operated between parallel polarizers, whereas IPS LCDs feature crossed polarizers. In many applications IPS LCDs have replaced TN LCDs, particularly in smartphones. Both the liquid crystal material and the alignment layer material contain ionic compounds. If an electric field of one particular polarity is applied for a long period of time, this ionic material is attracted to the surfaces and degrades the device performance. This is avoided either by applying an alternating current or by reversing the polarity of the electric field as the device is addressed (the response of the liquid crystal layer is identical, regardless of the polarity of the applied field).

Displays for a small number of individual digits or fixed symbols (as in digital watches and pocket calculators) can be implemented with independent electrodes for each segment.alphanumeric or variable graphics displays are usually implemented with pixels arranged as a matrix consisting of electrically connected rows on one side of the LC layer and columns on the other side, which makes it possible to address each pixel at the intersections. The general method of matrix addressing consists of sequentially addressing one side of the matrix, for example by selecting the rows one-by-one and applying the picture information on the other side at the columns row-by-row. For details on the various matrix addressing schemes see passive-matrix and active-matrix addressed LCDs.

LCDs, along with OLED displays, are manufactured in cleanrooms borrowing techniques from semiconductor manufacturing and using large sheets of glass whose size has increased over time. Several displays are manufactured at the same time, and then cut from the sheet of glass, also known as the mother glass or LCD glass substrate. The increase in size allows more displays or larger displays to be made, just like with increasing wafer sizes in semiconductor manufacturing. The glass sizes are as follows:

Until Gen 8, manufacturers would not agree on a single mother glass size and as a result, different manufacturers would use slightly different glass sizes for the same generation. Some manufacturers have adopted Gen 8.6 mother glass sheets which are only slightly larger than Gen 8.5, allowing for more 50 and 58 inch LCDs to be made per mother glass, specially 58 inch LCDs, in which case 6 can be produced on a Gen 8.6 mother glass vs only 3 on a Gen 8.5 mother glass, significantly reducing waste.AGC Inc., Corning Inc., and Nippon Electric Glass.

The origins and the complex history of liquid-crystal displays from the perspective of an insider during the early days were described by Joseph A. Castellano in Liquid Gold: The Story of Liquid Crystal Displays and the Creation of an Industry.IEEE History Center.Peter J. Wild, can be found at the Engineering and Technology History Wiki.

In 1888,Friedrich Reinitzer (1858–1927) discovered the liquid crystalline nature of cholesterol extracted from carrots (that is, two melting points and generation of colors) and published his findings at a meeting of the Vienna Chemical Society on May 3, 1888 (F. Reinitzer: Beiträge zur Kenntniss des Cholesterins, Monatshefte für Chemie (Wien) 9, 421–441 (1888)).Otto Lehmann published his work "Flüssige Kristalle" (Liquid Crystals). In 1911, Charles Mauguin first experimented with liquid crystals confined between plates in thin layers.

In 1922, Georges Friedel described the structure and properties of liquid crystals and classified them in three types (nematics, smectics and cholesterics). In 1927, Vsevolod Frederiks devised the electrically switched light valve, called the Fréedericksz transition, the essential effect of all LCD technology. In 1936, the Marconi Wireless Telegraph company patented the first practical application of the technology, "The Liquid Crystal Light Valve". In 1962, the first major English language publication Molecular Structure and Properties of Liquid Crystals was published by Dr. George W. Gray.RCA found that liquid crystals had some interesting electro-optic characteristics and he realized an electro-optical effect by generating stripe-patterns in a thin layer of liquid crystal material by the application of a voltage. This effect is based on an electro-hydrodynamic instability forming what are now called "Williams domains" inside the liquid crystal.

The MOSFET (metal-oxide-semiconductor field-effect transistor) was invented by Mohamed M. Atalla and Dawon Kahng at Bell Labs in 1959, and presented in 1960.Paul K. Weimer at RCA developed the thin-film transistor (TFT) in 1962.

In 1964, George H. Heilmeier, then working at the RCA laboratories on the effect discovered by Williams achieved the switching of colors by field-induced realignment of dichroic dyes in a homeotropically oriented liquid crystal. Practical problems with this new electro-optical effect made Heilmeier continue to work on scattering effects in liquid crystals and finally the achievement of the first operational liquid-crystal display based on what he called the George H. Heilmeier was inducted in the National Inventors Hall of FameIEEE Milestone.

In the late 1960s, pioneering work on liquid crystals was undertaken by the UK"s Royal Radar Establishment at Malvern, England. The team at RRE supported ongoing work by George William Gray and his team at the University of Hull who ultimately discovered the cyanobiphenyl liquid crystals, which had correct stability and temperature properties for application in LCDs.

The idea of a TFT-based liquid-crystal display (LCD) was conceived by Bernard Lechner of RCA Laboratories in 1968.dynamic scattering mode (DSM) LCD that used standard discrete MOSFETs.

On December 4, 1970, the twisted nematic field effect (TN) in liquid crystals was filed for patent by Hoffmann-LaRoche in Switzerland, (Swiss patent No. 532 261) with Wolfgang Helfrich and Martin Schadt (then working for the Central Research Laboratories) listed as inventors.Brown, Boveri & Cie, its joint venture partner at that time, which produced TN displays for wristwatches and other applications during the 1970s for the international markets including the Japanese electronics industry, which soon produced the first digital quartz wristwatches with TN-LCDs and numerous other products. James Fergason, while working with Sardari Arora and Alfred Saupe at Kent State University Liquid Crystal Institute, filed an identical patent in the United States on April 22, 1971.ILIXCO (now LXD Incorporated), produced LCDs based on the TN-effect, which soon superseded the poor-quality DSM types due to improvements of lower operating voltages and lower power consumption. Tetsuro Hama and Izuhiko Nishimura of Seiko received a US patent dated February 1971, for an electronic wristwatch incorporating a TN-LCD.

In 1972, the concept of the active-matrix thin-film transistor (TFT) liquid-crystal display panel was prototyped in the United States by T. Peter Brody"s team at Westinghouse, in Pittsburgh, Pennsylvania.Westinghouse Research Laboratories demonstrated the first thin-film-transistor liquid-crystal display (TFT LCD).high-resolution and high-quality electronic visual display devices use TFT-based active matrix displays.active-matrix liquid-crystal display (AM LCD) in 1974, and then Brody coined the term "active matrix" in 1975.

In 1972 North American Rockwell Microelectronics Corp introduced the use of DSM LCDs for calculators for marketing by Lloyds Electronics Inc, though these required an internal light source for illumination.Sharp Corporation followed with DSM LCDs for pocket-sized calculators in 1973Seiko and its first 6-digit TN-LCD quartz wristwatch, and Casio’s ‘Casiotron’. Color LCDs based on Guest-Host interaction were invented by a team at RCA in 1968.TFT LCDs similar to the prototypes developed by a Westinghouse team in 1972 were patented in 1976 by a team at Sharp consisting of Fumiaki Funada, Masataka Matsuura, and Tomio Wada,

In 1983, researchers at Brown, Boveri & Cie (BBC) Research Center, Switzerland, invented the passive matrix-addressed LCDs. H. Amstutz et al. were listed as inventors in the corresponding patent applications filed in Switzerland on July 7, 1983, and October 28, 1983. Patents were granted in Switzerland CH 665491, Europe EP 0131216,

The first color LCD televisions were developed as handheld televisions in Japan. In 1980, Hattori Seiko"s R&D group began development on color LCD pocket televisions.Seiko Epson released the first LCD television, the Epson TV Watch, a wristwatch equipped with a small active-matrix LCD television.dot matrix TN-LCD in 1983.Citizen Watch,TFT LCD.computer monitors and LCD televisions.3LCD projection technology in the 1980s, and licensed it for use in projectors in 1988.compact, full-color LCD projector.

In 1990, under different titles, inventors conceived electro optical effects as alternatives to twisted nematic field effect LCDs (TN- and STN- LCDs). One approach was to use interdigital electrodes on one glass substrate only to produce an electric field essentially parallel to the glass substrates.Germany by Guenter Baur et al. and patented in various countries.Hitachi work out various practical details of the IPS technology to interconnect the thin-film transistor array as a matrix and to avoid undesirable stray fields in between pixels.

Hitachi also improved the viewing angle dependence further by optimizing the shape of the electrodes (Super IPS). NEC and Hitachi become early manufacturers of active-matrix addressed LCDs based on the IPS technology. This is a milestone for implementing large-screen LCDs having acceptable visual performance for flat-panel computer monitors and television screens. In 1996, Samsung developed the optical patterning technique that enables multi-domain LCD. Multi-domain and In Plane Switching subsequently remain the dominant LCD designs through 2006.South Korea and Taiwan,

In 2007 the image quality of LCD televisions surpassed the image quality of cathode-ray-tube-based (CRT) TVs.LCD TVs were projected to account 50% of the 200 million TVs to be shipped globally in 2006, according to Displaybank.Toshiba announced 2560 × 1600 pixels on a 6.1-inch (155 mm) LCD panel, suitable for use in a tablet computer,transparent and flexible, but they cannot emit light without a backlight like OLED and microLED, which are other technologies that can also be made flexible and transparent.

In 2016, Panasonic developed IPS LCDs with a contrast ratio of 1,000,000:1, rivaling OLEDs. This technology was later put into mass production as dual layer, dual panel or LMCL (Light Modulating Cell Layer) LCDs. The technology uses 2 liquid crystal layers instead of one, and may be used along with a mini-LED backlight and quantum dot sheets.

Since LCDs produce no light of their own, they require external light to produce a visible image.backlight. Active-matrix LCDs are almost always backlit.Transflective LCDs combine the features of a backlit transmissive display and a reflective display.

CCFL: The LCD panel is lit either by two cold cathode fluorescent lamps placed at opposite edges of the display or an array of parallel CCFLs behind larger displays. A diffuser (made of PMMA acrylic plastic, also known as a wave or light guide/guiding plateinverter to convert whatever DC voltage the device uses (usually 5 or 12 V) to ≈1000 V needed to light a CCFL.

EL-WLED: The LCD panel is lit by a row of white LEDs placed at one or more edges of the screen. A light diffuser (light guide plate, LGP) is then used to spread the light evenly across the whole display, similarly to edge-lit CCFL LCD backlights. The diffuser is made out of either PMMA plastic or special glass, PMMA is used in most cases because it is rugged, while special glass is used when the thickness of the LCD is of primary concern, because it doesn"t expand as much when heated or exposed to moisture, which allows LCDs to be just 5mm thick. Quantum dots may be placed on top of the diffuser as a quantum dot enhancement film (QDEF, in which case they need a layer to be protected from heat and humidity) or on the color filter of the LCD, replacing the resists that are normally used.

WLED array: The LCD panel is lit by a full array of white LEDs placed behind a diffuser behind the panel. LCDs that use this implementation will usually have the ability to dim or completely turn off the LEDs in the dark areas of the image being displayed, effectively increasing the contrast ratio of the display. The precision with which this can be done will depend on the number of dimming zones of the display. The more dimming zones, the more precise the dimming, with less obvious blooming artifacts which are visible as dark grey patches surrounded by the unlit areas of the LCD. As of 2012, this design gets most of its use from upscale, larger-screen LCD televisions.

RGB-LED array: Similar to the WLED array, except the panel is lit by a full array of RGB LEDs. While displays lit with white LEDs usually have a poorer color gamut than CCFL lit displays, panels lit with RGB LEDs have very wide color gamuts. This implementation is most popular on professional graphics editing LCDs. As of 2012, LCDs in this category usually cost more than $1000. As of 2016 the cost of this category has drastically reduced and such LCD televisions obtained same price levels as the former 28" (71 cm) CRT based categories.

Monochrome LEDs: such as red, green, yellow or blue LEDs are used in the small passive monochrome LCDs typically used in clocks, watches and small appliances.

Mini-LED: Backlighting with Mini-LEDs can support over a thousand of Full-area Local Area Dimming (FLAD) zones. This allows deeper blacks and higher contrast ratio.MicroLED.)

Today, most LCD screens are being designed with an LED backlight instead of the traditional CCFL backlight, while that backlight is dynamically controlled with the video information (dynamic backlight control). The combination with the dynamic backlight control, invented by Philips researchers Douglas Stanton, Martinus Stroomer and Adrianus de Vaan, simultaneously increases the dynamic range of the display system (also marketed as HDR, high dynamic range television or called Full-area Local Area Dimming (FLAD)

The LCD backlight systems are made highly efficient by applying optical films such as prismatic structure (prism sheet) to gain the light into the desired viewer directions and reflective polarizing films that recycle the polarized light that was formerly absorbed by the first polarizer of the LCD (invented by Philips researchers Adrianus de Vaan and Paulus Schaareman),

Due to the LCD layer that generates the desired high resolution images at flashing video speeds using very low power electronics in combination with LED based backlight technologies, LCD technology has become the dominant display technology for products such as televisions, desktop monitors, notebooks, tablets, smartphones and mobile phones. Although competing OLED technology is pushed to the market, such OLED displays do not feature the HDR capabilities like LCDs in combination with 2D LED backlight technologies have, reason why the annual market of such LCD-based products is still growing faster (in volume) than OLED-based products while the efficiency of LCDs (and products like portable computers, mobile phones and televisions) may even be further improved by preventing the light to be absorbed in the colour filters of the LCD.

A pink elastomeric connector mating an LCD panel to circuit b