tft lcd display definition brands
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.
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.
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
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.
Asia has long dominated the display module TFT LCD manufacturers’ scene. After all, most major display module manufacturers can be found in countries like China, South Korea, Japan, and India.
However, the United States doesn’t fall short of its display module manufacturers. Most American module companies may not be as well-known as their Asian counterparts, but they still produce high-quality display products for both consumers and industrial clients.
In this post, we’ll list down 7 best display module TFT LCD manufacturers in the USA. We’ll see why these companies deserve recognition as top players in the American display module industry.
STONE Technologies is a leading display module TFT LCD manufacturer in the world. The company is based in Beijing, China, and has been in operations since 2010. STONE quickly grew to become one of the most trusted display module manufacturers in 14 years.
Now, let’s move on to the list of the best display module manufacturers in the USA. These companies are your best picks if you need to find a display module TFT LCD manufacturer based in the United States:
Planar Systems is a digital display company headquartered in Hillsboro, Oregon. It specializes in providing digital display solutions such as LCD video walls and large format LCD displays.
Planar’s manufacturing facilities are located in Finland, France, and North America. Specifically, large-format displays are manufactured and assembled in Albi, France.
Another thing that makes Planar successful is its relentless focus on its customers. The company listens to what each customer requires so that they can come up with effective display solutions to address these needs.
Microtips Technology is a global electronics manufacturer based in Orlando, Florida. The company was established in 1990 and has grown into a strong fixture in the LCD industry.
What makes Microtips a great display module TFT LCD manufacturer in the USA lies in its close ties with all its customers. It does so by establishing a good rapport with its clients starting from the initial product discussions. Microtips manages to keep this exceptional rapport throughout the entire client relationship by:
Displaytech is an American display module TFT LCD manufacturer headquartered in Carlsbad, California. It was founded in 1989 and is part of several companies under the Seacomp group. The company specializes in manufacturing small to medium-sized LCD modules for various devices across all possible industries.
The company also manufactures embedded TFT devices, interface boards, and LCD development boards. Also, Displaytech offers design services for embedded products, display-based PCB assemblies, and turnkey products.
Displaytech makes it easy for clients to create their own customized LCD modules. There is a feature called Design Your Custom LCD Panel found on their site. Clients simply need to input their specifications such as their desired dimensions, LCD configuration, attributes, connector type, operating and storage temperature, and other pertinent information. Clients can then submit this form to Displaytech to get feedback, suggestions, and quotes.
Clients are assured of high-quality products from Displaytech. This is because of the numerous ISO certifications that the company holds for medical devices, automotive, and quality management. Displaytech also holds RoHS and REACH certifications.
A vast product range, good customization options, and responsive customer service – all these factors make Displaytech among the leading LCD manufacturers in the USA.
Products that Phoenix Display offers include standard, semi-custom, and fully-customized LCD modules. Specifically, these products comprise Phoenix Display’s offerings:
Phoenix Display also integrates the display design to all existing peripheral components, thereby lowering manufacturing costs, improving overall system reliability, and removes unnecessary interconnects.
Clients flock to Phoenix Display because of their decades-long experience in the display manufacturing field. The company also combines its technical expertise with its competitive manufacturing capabilities to produce the best possible LCD products for its clients.
True Vision Displays is an American display module TFT LCD manufacturing company located at Cerritos, California. It specializes in LCD display solutions for special applications in modern industries. Most of their clients come from highly-demanding fields such as aerospace, defense, medical, and financial industries.
The company produces several types of TFT LCD products. Most of them are industrial-grade and comes in various resolution types such as VGA, QVGA, XGA, and SXGA. Clients may also select product enclosures for these modules.
All products feature high-bright LCD systems that come from the company’s proprietary low-power LED backlight technology. The modules and screens also come in ruggedized forms perfect for highly-demanding outdoor industrial use.
Slow but steady growth has always been True Vision Display’s business strategy. And the company continues to be known globally through its excellent quality display products, robust research and development team, top-of-the-line manufacturing facilities, and straightforward client communication.
LXD Incorporated is among the earliest LCD manufacturers in the world. The company was founded in 1968 by James Fergason under the name International Liquid Xtal Company (ILIXCO). Its first headquarters was in Kent, Ohio. At present, LXD is based in Raleigh, North Carolina.
All of their display modules can be customized to fit any kind of specifications their clients may require. Display modules also pass through a series of reliability tests before leaving the manufacturing line. As such, LXD’s products can withstand extreme outdoor environments and operates on a wide range of temperature conditions.
Cystalfontz America is a leading supplier and manufacturer of HMI display solutions. The company is located in Spokane Valley, Washington. It has been in the display solutions business since 1998.
Crystalfontz takes pride in its ISO 9001 certification, meaning the company has effective quality control measures in place for all of its products. After all, providing high-quality products to all customers remains the company’s topmost priority. Hence, many clients from small hobbyists to large top-tier American companies partner with Crystalfontz for their display solution needs.
We’ve listed the top 7 display module TFT LCD manufacturers in the USA. All these companies may not be as well-known as other Asian manufacturers are, but they are equally competent and can deliver high-quality display products according to the client’s specifications. Contact any of them if you need a US-based manufacturer to service your display solutions needs.
We also briefly touched on STONE Technologies, another excellent LCD module manufacturer based in China. Consider partnering with STONE if you want top-of-the-line smart LCD products and you’re not necessarily looking for a US-based manufacturer. STONE will surely provide the right display solution for your needs anywhere you are on the globe.
Get rich colors, detailed images, and bright graphics from an LCD with a TFT screen. Our standard Displaytech TFT screens start at 1” through 7” in diagonal size and have a variety of display resolutions to select from. Displaytech TFT displays meet the needs for products within industrial, medical, and consumer applications.
TFT displays are LCD modules with thin-film transistor technology. The TFT display technology offers full color RGB showcasing a range of colors and hues. These liquid crystal display panels are available with touchscreen capabilities, wide viewing angles, and bright luminance for high contrast.
Our TFT displays have LVDS, RGB, SPI, and MCU interfaces. All Displaytech TFT LCD modules include an LED backlight, FPC, driver ICs, and the LCD panel.
We offer resistive and capacitive touch screens for our 2.8” and larger TFT modules. Our TFT panels have a wide operating temperature range to suit a variety of environments. All Displaytech LCDs are RoHS compliant.
We also offer semi-customization to our standard TFT screens. This is a cost-optimized solution to make a standard product better suit your application’s needs compared to selecting a fully custom TFT LCD. Customizations can focus on cover glass, mounting / enclosures, and more - contact us to discuss your semi-custom TFT solution.
The two buzzwords the tech world has been chatting about for a number of years now is IPS, (In-Plane Switching) screen technology used for liquid crystal displays or LCD’s for short, and TFT (Thin-Film-Transistor) an active matrix screen technology, which is more expensive, but a sharper image.
Designed in the 1980’s, but not introduced until nearly a decade later, in 1996, by Hitachi, IPS technology is nothing new, and a type of LCD design that affords greater viewing angles and higher-quality color reproduction than the traditional TN or Twisted Nematic LCDs.
TFT (Thin-Film-Transistor) Liquid Crystal Display is a thin display type, where a transistor embedded into each crystal gate; these transistors are then printed on thin-transparent film. The technology was designed to improve image qualities, such as contrast and addressability.
Also designed in the late 1980’s, TFT display technologies is just another variation of LCD displays that offer greater color, contrast, and response times as opposed to available passive matrix LCD’s. One of the primary differences between IPS and TFT display technologies is the cost. IPS is more expensive than TN technology. However, there are some key differences between the two that should be noted.
Before we go into the differences, let’s talk about features of each technology. Note that we’re not talking TVs, computer, or tablets, but screens on a much smaller scale, (think 7” or smaller) which uses different rules to fit that scale. First, it’s interesting to discover that the TFT display technologies is the most common type of color display technology; more monochrome displays still out-sell color, due to lower cost and lower power consumption, however, the narrow poor visibility of TFTs in direct sunlight is their downside; but I’m getting ahead of myself here.
IPS technology has come a long way in regards to cell phones and other LCD screens that are even much smaller. (Picture digital clocks on a radio, microwave, and hand-held games) Some of the features of an IPS screen include:Wider viewing angles – crystals are aligned horizontally rather than vertically, so it allows for better angled viewing, perfect for smaller screens, where you need to rotate the screen for better viewing
Brilliant color image – this is a huge advance in technology, from a Twisted Nematic (TN) display that only produced 6-bit color, to an 8-bit color display with the IPS technology
TFT display technologies have developed over the years and have become quite popular in tech circles. The features offered with this advancing technology are:Superior color display – for technology that requires it or for consumers that desire color screens
Features a longer half-life, (half-life is the amount of time in hours before the display is 50% as bright as when it was first turned on), than OLEDs and comes in varying sizes, from under an inch up to over 15 inches
Variety of displays, which can be interfaced through a variety of bus types, including 18 and 24 bit for red/green/blue, LVDS, and 8 bit and 16 bit for a CPU – many controllers allow for two or more different types of interfaces on the same TFT screen
Let me explain. As you can see, both have excellent color display and clarity; however, IPS screens offer greater color reproduction and viewing angles because of the way crystal orientation and polarizers are arranged. In a TFT screen, the structure of the crystals results in angular retardation in the light. The IPS screens thus offer less distortion properties. Other differences include power consumption and cost. With IPS screens, it takes more power (up to 15% more) than with a TFT screen. If you’re on a monitor, such as a computer screen that’s bigger than 7 inches, it will drain your battery faster than if you’re on a 3.5” screen. Regarding cost, IPS panels are more expensive to produce than TFT panels.
The color channels increase from 6 bits (TN displays) to 8 bits (IPS displays) to ensure the precision of shades per color channel, thus increasing manufacturing costs
If you want the benefits of having a Smartphone without a huge price tag, then TFT devices are your best bet. Another difference is that IPS screens have longer response times than TFT screens, so the lag output is greater. A few other key differences to be aware of are that with IPS panels, you get a bigger variety of panels, as was discussed above, with their super, advanced, and so forth developments, giving the consumer options, and IPS screens that can display 24-bit TrueColor; they also stay color-accurate and remain stable.
Now we will go over the downside of IPS screens, which we briefly touched on above, which includes a major disadvantage: cost. If you’re just looking for an average Smartphone or don’t need all the fancy coloring and clarity for LCD displays, then cost may not be a big factor; however, this is the main reason why IPS technology is beginning to come down. As with every new invention, discovery or technology, demand is everything. Another disadvantage is that colors may not always transcribe correctly or accurately, which may or may not be a deterrent. Also, high resolutions are not always readily available for personal applications. In certain circumstances, the brightness may not be enough, especially in darkness.
Steve Jobs said it best: “Design is not just what it looks like and feels like. Design is how it works.” I tend to agree with him. With TFT display technologies, less energy consumption is a big deal, especially when dealing with bigger screens, and of course less electricity means lower cost, overall. The visibility is sharper, meaning no geometric distortion, which is great for these tired, old eyes. The response time and physical design of the screens are also appealing. TFT displays can also save space and be placed virtually anywhere in an office or home, because of the brightly lit feature and crisp clear images.
Some cons of TFT screens deal with the viewing angle, which create distortion, resulting in a less-than-perfect image. Static resolution, meaning the resolution can’t be changed, may also cause a problem, but newer models seem to have tackled that issue. The accuracy of the display of colors is not perfect, specifically strong blacks and bright whites, so when printing an image, it may not display the spectrum of colors.
And there you have it. In the future, even this superb technology will change and new, more exciting technology will take its place. But until then, IPS & TFT screens are forging ahead with their own advances and improvements, so stayed tune. You don’t want to miss it.
Focus Display Solutions (www.FocusLCDs.com) offers off-the-shelf Color TFT display technologies in both TN and IPS. Many of the color modules contain built in touch panels.
There are many LCD display types to choose from. Some are new cutting edge technology and other are older legacy types of displays. Although even some of the legacy type of LCD displays make use of cutting edge technology. The goal of this article is to provide the reader with a brief overview of the uses, advantages and disadvantages of each type of display.
Segment LCD’s, also called static or direct drive are an older technology but are still in heavy use today. These displays are reliable and have been in use for many years. They show no signs of going away anytime soon.
The goal of this display is simplicity. Their only job is to display letters, numbers and icons. There is no 3-D effect or range of brilliant colors and most do not contain a touch screen or any other type of human interface. They normally are not equipped wit a controller/driver chip.
In fact, you could reduce the static/direct drive LCD down to the simple formula of one pin equals one segment. If you need a display that contains a 7 segment number, you need 7 pins. The exception to this is if you increase the number of backplanes and convert this to a multiplex display.
The formula for a multiplex display is a little more complicated. One pin equals 2 or 4 segments. The advantage of multiplexing is that you reduce the number of pins which, in turn, reduces the cost of the display and the amount of time required to mount the display to a PCB.
One disadvantage of multiplex display over direct drive displays is that the refresh rate is slower and this may allow the segments that are ON to ‘fade’ or not look as sharp. Some times this is referred to as ‘ghosting’. This is not a very common occurrence as the technology has improved since the days of pagers and low cost calculators.
LCD display type to use we have a general rule: If the total number of segments is 20 or less, we advise a static (direct drive) displaysince a display with 20 pins is low cost to build and to install on the PCB.
graphics type of LCD display that makes use of the controller driver chip. The controller driver chip allow the number of connections for multiple segments to be reduced to 14 or 16 pins. This LCD technology is covered later in the article.
While monochrome displays are simple and can come across as somewhat boring, there are some key advantages to consider when choosing which of the LCD display types to go with.
advantage of the monochrome LCD display is that they are not power hungry. They operate with very little current draw. This becomes an ideal choice when the only power you have is a battery. These displays are built to operate at 3.0V, 3.3V (in some case they can operate as low as 1.7V) and 5V. The current draw for a display with no backlight can run as low as 6uA per cm^2. (Note: The lower the operating temperature of the LCD, the greater the power required).
If all you need to display is what time it is, the current temperature, or the number of gallons, and your customer does not wish to pay for vibrant, flashy power-hungry color, then this display will work perfectly for you.
The majority of the static or multiplex displays we offer have been customized to meet the customer’s requirements. This is a great advantage to consider when choosing one of the LCD display types you will use in your product.
A customized static or multiplex display allows you to have the display built to the dimensions you require. You can select the following options:Temperature range to operate in
The tooling or NRE (non-recurring engineering cost) of this type of display is much lower than newer technologies and the MOQ (minimum order quantities) are also lower than other types of displays.
With the advent of TFT LCD display technology, advertisers now have tools that were not available to them before. The proper and efficient utilization of these tools is the topic of many discussion and articles. How can this technology help advertisers deliver their message? We have seen how our surroundings have been bombarded by displays of LED and LCD monitors asking us to buy this or go to that. Consumers do see these advertisements and they do catch the people’s attention; however, are they catching them for the right reasons?
Technology harnessing a TFT module can be double-edged swords. On the one hand, the technology can aid in the delivery of the message; on the other, it can distract the consumers from your real message. When that happens, it means both technology and execution failed to coordinate and work with one another. If there is a disconnect between the message and the medium, the capital used to acquire such technology is wasted.
It may seem obvious–the goal of the display is to sell your brand. However, it is not that simple. You should also think of how your display can aid in the experience of your consumers and how they are going to perceive your brand.
By size, we mean the size of the screen, which again is dependent on the first two factors above: message and location. Outdoor signage would likely be bigger than indoor ones. They also tend to be brighter than indoor displays and are matte-finished since they’re less prone to bright and glaring light. Obviously, outdoor screens not only should be bigger, but should also be weatherproof. Take note of these factors before making a purchase.
The question to answer when it comes to resolution is how far do you want your screen to be visible? The larger the area, the greater the impact and the more engaging your display becomes. Also, consider your audience’s viewing distance: how far is your audience from the display? Determine these and you’ll be able to choose the perfect resolution for your display.
Glass substrate with ITO electrodes. The shapes of these electrodes will determine the shapes that will appear when the LCD is switched ON. Vertical ridges etched on the surface are smooth.
A liquid-crystal display (LCD) is a flat-panel display or other electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizers. Liquid crystals do not emit light directlybacklight or reflector to produce images in color or monochrome.seven-segment displays, as in a digital clock, are all good examples of devices with these displays. They use the same basic technology, except that arbitrary images are made from a matrix of small pixels, while other displays have larger elements. LCDs can either be normally on (positive) or off (negative), depending on the polarizer arrangement. For example, a character positive LCD with a backlight will have black lettering on a background that is the color of the backlight, and a character negative LCD will have a black background with the letters being of the same color as the backlight. Optical filters are added to white on blue LCDs to give them their characteristic appearance.
LCDs are used in a wide range of applications, including LCD televisions, computer monitors, instrument panels, aircraft cockpit displays, and indoor and outdoor signage. Small LCD screens are common in LCD projectors and portable consumer devices such as digital cameras, watches, 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 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.
Today, most LCD screens are being designed with an LED backlight instead of the traditional CCFL backlight, while that backlight is dynamically controlled with the video information (dynamic backlight control). The combination with the dynamic backlight control, invented by Philips researchers Douglas Stanton, Martinus Stroomer and Adrianus de Vaan, simultaneously increases the dynamic range of the display system (also marketed as HDR, high dynamic range television or FLAD, full-area local area dimming).
The LCD backlight systems are made highly efficient by applying optical films such as prismatic structure (prism sheet) to gain the light into the desired viewer directions and reflective polarizing films that recycle the polarized light that was formerly absorbed by the first polarizer of the LCD (invented by Philips researchers Adrianus de Vaan and Paulus Schaareman),
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 board traces, shown next to a centimeter-scale ruler. The conductive and insulating layers in the black stripe are very small.
A standard television receiver screen, a modern LCD panel, has over six million pixels, and they are all individually powered by a wire network embedded in the screen. The fine wires, or pathways, form a grid with vertical wires across the whole screen on one side of the screen and horizontal wires across the whole screen on the other side of the screen. To this grid each pixel has a positive connection on one side and a negative connection on the other side. So the total amount of wires needed for a 1080p display is 3 x 1920 going vertically and 1080 going horizontally for a total of 6840 wires horizontally and vertically. That"s three for red, green and blue and 1920 columns of pixels for each color for a total of 5760 wires going vertically and 1080 rows of wires going horizontally. For a panel that is 28.8 inches (73 centimeters) wide, that means a wire density of 200 wires per inch along the horizontal edge.
The LCD panel is powered by LCD drivers that are carefully matched up with the edge of the LCD panel at the factory level. The drivers may be installed using several methods, the most common of which are COG (Chip-On-Glass) and TAB (Tape-automated bonding) These same principles apply also for smartphone screens that are much smaller than TV screens.anisotropic conductive film or, for lower densities, elastomeric connectors.
Monochrome and later color passive-matrix LCDs were standard in most early laptops (although a few used plasma displaysGame Boyactive-matrix became standard on all laptops. The commercially unsuccessful Macintosh Portable (released in 1989) was one of the first to use an active-matrix display (though still monochrome). Passive-matrix LCDs are still used in the 2010s for applications less demanding than laptop computers and TVs, such as inexpensive calculators. In particular, these are used on portable devices where less information content needs to be displayed, lowest power consumption (no backlight) and low cost are desired or readability in direct sunlight is needed.
A comparison between a blank passive-matrix display (top) and a blank active-matrix display (bottom). A passive-matrix display can be identified when the blank background is more grey in appearance than the crisper active-matrix display, fog appears on all edges of the screen, and while pictures appear to be fading on the screen.
Displays having a passive-matrix structure are employing Crosstalk between activated and non-activated pixels has to be handled properly by keeping the RMS voltage of non-activated pixels below the threshold voltage as discovered by Peter J. Wild in 1972,
STN LCDs have to be continuously refreshed by alternating pulsed voltages of one polarity during one frame and pulses of opposite polarity during the next frame. Individual pixels are addressed by the corresponding row and column circuits. This type of display is called response times and poor contrast are typical of passive-matrix addressed LCDs with too many pixels and driven according to the "Alt & Pleshko" drive scheme. Welzen and de Vaan also invented a non RMS drive scheme enabling to drive STN displays with video rates and enabling to show smooth moving video images on an STN display.
Bistable LCDs do not require continuous refreshing. Rewriting is only required for picture information changes. In 1984 HA van Sprang and AJSM de Vaan invented an STN type display that could be operated in a bistable mode, enabling extremely high resolution images up to 4000 lines or more using only low voltages.
High-resolution color displays, such as modern LCD computer monitors and televisions, use an active-matrix structure. A matrix of thin-film transistors (TFTs) is added to the electrodes in contact with the LC layer. Each pixel has its own dedicated transistor, allowing each column line to access one pixel. When a row line is selected, all of the column lines are connected to a row of pixels and voltages corresponding to the picture information are driven onto all of the column lines. The row line is then deactivated and the next row line is selected. All of the row lines are selected in sequence during a refresh operation. Active-matrix addressed displays look brighter and sharper than passive-matrix addressed displays of the same size, and generally have quicker response times, producing much better images. Sharp produces bistable reflective LCDs with a 1-bit SRAM cell per pixel that only requires small amounts of power to maintain an image.
Segment LCDs can also have color by using Field Sequential Color (FSC LCD). This kind of displays have a high speed passive segment LC