tft display construction pricelist

TFT stands for Thin Film Transistor, a type of LCD flat-panel display screen, in which each pixel is controlled by a range of one to four transistors. TFT screens are sometimes called active-matrix LCDs in contrast to passive-matrix LCDs, which are direct-driven with a limited number of segments.

TFTs are made from a thin film of amorphous silicon that is deposited on a glass panel. Transistors take up only a small fraction of the area of each pixel and the rest of the silicon film is etched away to allow light to easily pass through it.

Different applications require different customizations. Our team of Display Engineers will work with you every step of the way to make sure you get the best display solution for the product that you are designing.

If you are creating a new design and your volume is high enough to justify the price difference between a standard and a custom display (most of the times it’s just pennies, so it’s worth it!)

Most of the time our customers start with a standard off-the-shelf product and quickly realize that they need to make changes to be able to make the display fit their designs.

These are the most common customizations. If you can’t find what you are looking for, don’t hesitate to contact us. Let our Display Engineers guide you through the customization process. To find out more about our EDSP Process, visit our Custom Displays page.

The price of LCD display panels for TVs is still falling in November and is on the verge of falling back to the level at which it initially rose two years ago (in June 2020). Liu Yushi, a senior analyst at CINNO Research, told China State Grid reporters that the wave of “falling tide” may last until June this year. For related panel companies, after the performance surge in the past year, they will face pressure in 2022.

LCD display panel prices for TVs will remain at a high level throughout 2021 due to the high base of 13 consecutive months of increase, although the price of LCD display panels peaked in June last year and began to decline rapidly. Thanks to this, under the tight demand related to panel enterprises last year achieved substantial profit growth.

According to China State Grid, the annual revenue growth of major LCD display panel manufacturers in China (Shentianma A, TCL Technology, Peking Oriental A, Caihong Shares, Longteng Optoelectronics, AU, Inolux Optoelectronics, Hanyu Color Crystal) in 2021 is basically above double digits, and the net profit growth is also very obvious. Some small and medium-sized enterprises directly turn losses into profits. Leading enterprises such as BOE and TCL Technology more than doubled their net profit.

TCL explained that the major reasons for the significant year-on-year growth in revenue and profit were the significant year-on-year growth of the company’s semiconductor display business shipment area, the average price of major products and product profitability, and the optimization of the business mix and customer structure further enhanced the contribution of product revenue.

“There are two main reasons for the ideal performance of domestic display panel enterprises.” A color TV industry analyst believes that, on the one hand, under the effect of the epidemic, the demand for color TV and other electronic products surges, and the upstream raw materials are in shortage, which leads to the short supply of the panel industry, the price rises, and the corporate profits increase accordingly. In addition, as Samsung and LG, the two-panel giants, gradually withdrew from the LCD panel field, they put most of their energy and funds into the OLED(organic light-emitting diode) display panel industry, resulting in a serious shortage of LCD display panels, which objectively benefited China’s local LCD display panel manufacturers such as BOE and TCL China Star Optoelectronics.

In the first quarter of this year, the retail volume of China’s color TV market was 9.03 million units, down 8.8% year on year. Retail sales totaled 28 billion yuan, down 10.1 percent year on year. Under the situation of volume drop, the industry expects this year color TV manufacturers will also set off a new round of LCD display panel prices war.

Focus Displays offers a wide range of standard full color TFT displays. 64 million unique colors, high brightness, sharp contrast, -30C operating temperature, and fast response time are all good descriptions of a TFT display. This is why TFT technology is one of the most popular choices for a new product.

Thin Film Transistor (TFT) display technology can be seen in products such as laptop computers, cell phones, tablets, digital cameras, and many other products that require color. TFT’s are active matrix displays which offers exceptional viewing experiences especially when compared to other passive matrix technologies. The clarity on TFT displays is outstanding; and they possess a longer half-life than some types of OLEDs and range in sizes from less than an inch to over 15 inches.

CCFL’s are still available, but are becoming a legacy (obsolete) component. TFT displays equipped with a CCFL require higher MOQs (Minimum Order Quantities) than displays with LED backlights.

The majority of TFT displays contain a touch panel, or touch screen. The touch panel is a touch-sensitive transparent overlay mounted on the front of the display glass. Allowing for interaction between the user and the LCD display.

Some touch panels require an independent driver IC; which can be included in the TFT display module or placed on the customer’s Printed Circuit Board (PCB). Touch screens make use of coordinate systems to locate where the user touched the screen.

Resistive touch panels are the lowest cost option and are standard equipment on many TFT modules. They are more common on smaller TFT displays, but can still be incorporated on larger modules.

Contrast ratio, or static contrast ratio, is one way to measure the sharpness of the TFT LCD display. This ratio is the difference between the darkest black and the brightest white the display is able to produce. The higher the number on the left, the sharper the image. A typical contrast ratio for TFT may be 300:1. This number ratio means that the white is 300 times brighter than the black.

TFT LCD displays are measured in inches; this is the measurement of the diagonal distance across the glass. Common TFT sizes include: 1.77”, 2.4”, 2.8”, 3”, 4.3”, 5”, 5.7”, 5.8”, 7”, 10.2”, 12.1 and 15”.

As a general rule, the larger the size of the glass the higher the cost of the display, but there are exceptions to this rule. A larger display may be less expensive than a smaller display if the manufacture produces higher quantities of the larger displays. When selecting your color display, be sure to ask what the cost is for one size smaller and one size larger. It may be worth modifying your design requirements.

TFT resolution is the number of dots or pixels the display contains. It is measured by the number of dots along the horizontal (X axis) and the dots along the vertical (Y axis).

The higher the resolution, the more dots per square inch (DPI), the sharper the display will look. A higher resolution results in a higher cost. One reason for the increase in cost is that more driver chips are necessary to drive each segment.

Certain combinations of width and height are standardized and typically given a name and a letter representation that is descriptive of its dimensions. Popular names given to the TFT LCD displays resolution include:

Transmissive displays must have the backlight on at all times to read the display, but are not the best option in direct sunlight unless the backlight is 750 Nits or higher. A majority of TFT displays are Transmissive, but they will require more power to operate with a brighter backlight.

Transflective displays are readable with the backlight off provided there is enough ambient light. Transflective displays are more expensive than Transmissive also there may be a larger MOQ for Transflective. However, Transflective displays are the best option for direct sunlight.

Drivers update and refresh the pixels (Picture Elements) of a display. Each driver is assigned a set number of pixels. If there are more pixels than a single driver can handle, then an additional drivers are added.

A primary job of the driver is to refresh each pixel. In passive TFT displays, the pixel is refreshed and then allowed to slowly fade (aka decay) until refreshed again. The higher the refresh frequency, the sharper the displays contrast.

The controller does just what its name suggest. It controls the drivers. There is only one controller per display no matter how many drivers. A complex graphic display with several thousand pixels will contain one controller and several drivers.

The TFT display (minus touch screen/backlight) alone will contain one controller/driver combination. These are built into the display so the design engineer does not need to locate the correct hardware.

If you do not see a Thin Film Transistor (TFT) Display module that meets your specifications, or you need a replacement TFT, we can build a custom TFT displays to meet your requirements. Custom TFTs require a one-time tooling fee and may require higher MOQs.

Ready to order samples for your TFT design? Contact one of our US-based technical support people today concerning your design requirements. Note: We can provide smaller quantities for samples and prototyping.

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.

A TFT LCD,  or a thin film transistor liquid crystal display, is one of the fastest growing forms of display technology today. The thin film transistor (TFT) is a type of semiconductor device used in display technology to enhance efficiency, compactness, and cost of the product. In conjunction with its semiconductor properties, the TFT LCD is an active matrix display, controlling pixels individually and actively rather than passively, furthering the benefits of this semiconductor device.

The TFT LCD is built with three key layers. Two sandwiching layers consist of glass substrates, though one includes TFTs while the other has an RGB, or red green blue, color filter. The layer between the glass layers is a liquid crystal layer.

The Architecture of a TFT Pixelbelow) from the other substrate layer of the device and control the amount of voltage applied to their respective sub-pixels. This layer also has pixel electrodes between the substrate and the liquid crystal layer. Electrodes are conductors that channel electricity into or out of something, in this case, pixels.

Between the two substrate layers lie liquid crystals. Together, the liquid crystal molecules may behave as a liquid in terms of movement, but it holds its structure as a crystal. There are a variety of chemical formulas available for use in this layer. Typically, liquid crystals are aligned to position the molecules in a certain way to induce specific behaviors of passing light through the polarization of the light waves. To do this, either a magnetic or electric field must be used; however, with displays, for a magnetic field to be usable, it will be too strong for the display itself, and thus electric fields, using very low power and requiring no current, are used.

Before applying an electric field to the crystals between the electrodes, the alignment of the crystals is in a 90 degree twisted pattern, allowing a properly crystal-polarized light to pass through the surface polarizer in a display’s “normal white” mode. This state is caused by electrodes that are purposely coated in a material that orients the structure with this specific twist.

However, when the electric field is applied, the twist is broken as the crystals straighten out, otherwise known as re-aligning. The passing light can still pass through the back polarizer, but because the crystal layer does not polarize the lights to pass through the surface polarizer, light is not transmitted to the surface, thus an opaque display. If the voltage is lessened, only some crystals re-align, allowing for a partial amount of light to pass and creating different shades of grey (levels of light). This effect is called the twisted nematic effect.

Fig. 3:The top row characterizes the nature of alignment in using IPS as well as the quality of viewing angles. The bottom row displays how the twisted nematic is used to align the crystals and how viewing angles are affected by it.

The light that passes through the device is sourced from the backlight which can shine light from the back or the side of the display. Because the LCD does not produce its own light, it needs to use the backlight in the OLED) have come into use as well. Typically white, this light, if polarized correctly, will pass through the RGB color filter of the surface substrate layer, displaying the color signaled for by the TFT device.

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

Liquids that twist the plane of polarized light by 90° are referred to as TN (Twisted Nematic). STN (Super Twisted Nematic) liquids twist the plane of polarized light by at least 180°. This gives the display improved contrast. However, this technology does color the display to a certain extent. The most common colors are referred to as yellow-green and blue mode. There is also a gray mode, which in practice is more blue than gray, however.

In order to counteract the undesired color effect, the FSTN technology uses an additional foil on the outer side, but this causes a loss of light and means that this technology is only effective with lit displays.

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

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

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

12°° displays (top view, TV) are best built into a table-top unit. All displays can be read vertically from the front.Reflective, transflective, transmissive

However, the lighting also determines the optical impression made by the display, and the display mode; blue or yellow-green – does not always have an influence. Below you can see the EAP162-3N display with different types of lighting by way of example:Lighting

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

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

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

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

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

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

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

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

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

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

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

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

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

A thin-film-transistor liquid-crystal display (TFT LCD) is a variant of a liquid-crystal display that uses thin-film-transistor technologyactive matrix LCD, in contrast to passive matrix LCDs or simple, direct-driven (i.e. with segments directly connected to electronics outside the LCD) LCDs with a few segments.

In February 1957, John Wallmark of RCA filed a patent for a thin film MOSFET. Paul K. Weimer, also of RCA implemented Wallmark"s ideas and developed the thin-film transistor (TFT) in 1962, a type of MOSFET distinct from the standard bulk MOSFET. It was made with thin films of cadmium selenide and cadmium sulfide. The idea of a TFT-based liquid-crystal display (LCD) was conceived by Bernard Lechner of RCA Laboratories in 1968. In 1971, Lechner, F. J. Marlowe, E. O. Nester and J. Tults demonstrated a 2-by-18 matrix display driven by a hybrid circuit using the dynamic scattering mode of LCDs.T. Peter Brody, J. A. Asars and G. D. Dixon at Westinghouse Research Laboratories developed a CdSe (cadmium selenide) TFT, which they used to demonstrate the first CdSe thin-film-transistor liquid-crystal display (TFT LCD).active-matrix liquid-crystal display (AM LCD) using CdSe TFTs in 1974, and then Brody coined the term "active matrix" in 1975.high-resolution and high-quality electronic visual display devices use TFT-based active matrix displays.

The liquid crystal displays used in calculators and other devices with similarly simple displays have direct-driven image elements, and therefore a voltage can be easily applied across just one segment of these types of displays without interfering with the other segments. This would be impractical for a large display, because it would have a large number of (color) picture elements (pixels), and thus it would require millions of connections, both top and bottom for each one of the three colors (red, green and blue) of every pixel. To avoid this issue, the pixels are addressed in rows and columns, reducing the connection count from millions down to thousands. The column and row wires attach to transistor switches, one for each pixel. The one-way current passing characteristic of the transistor prevents the charge that is being applied to each pixel from being drained between refreshes to a display"s image. Each pixel is a small capacitor with a layer of insulating liquid crystal sandwiched between transparent conductive ITO layers.

The circuit layout process of a TFT-LCD is very similar to that of semiconductor products. However, rather than fabricating the transistors from silicon, that is formed into a crystalline silicon wafer, they are made from a thin film of amorphous silicon that is deposited on a glass panel. The silicon layer for TFT-LCDs is typically deposited using the PECVD process.

Polycrystalline silicon is sometimes used in displays requiring higher TFT performance. Examples include small high-resolution displays such as those found in projectors or viewfinders. Amorphous silicon-based TFTs are by far the most common, due to their lower production cost, whereas polycrystalline silicon TFTs are more costly and much more difficult to produce.

The twisted nematic display is one of the oldest and frequently cheapest kind of LCD display technologies available. TN displays benefit from fast pixel response times and less smearing than other LCD display technology, but suffer from poor color reproduction and limited viewing angles, especially in the vertical direction. Colors will shift, potentially to the point of completely inverting, when viewed at an angle that is not perpendicular to the display. Modern, high end consumer products have developed methods to overcome the technology"s shortcomings, such as RTC (Response Time Compensation / Overdrive) technologies. Modern TN displays can look significantly better than older TN displays from decades earlier, but overall TN has inferior viewing angles and poor color in comparison to other technology.

Most TN panels can represent colors using only six bits per RGB channel, or 18 bit in total, and are unable to display the 16.7 million color shades (24-bit truecolor) that are available using 24-bit color. Instead, these panels display interpolated 24-bit color using a dithering method that combines adjacent pixels to simulate the desired shade. They can also use a form of temporal dithering called Frame Rate Control (FRC), which cycles between different shades with each new frame to simulate an intermediate shade. Such 18 bit panels with dithering are sometimes advertised as having "16.2 million colors". These color simulation methods are noticeable to many people and highly bothersome to some.gamut (often referred to as a percentage of the NTSC 1953 color gamut) are also due to backlighting technology. It is not uncommon for older displays to range from 10% to 26% of the NTSC color gamut, whereas other kind of displays, utilizing more complicated CCFL or LED phosphor formulations or RGB LED backlights, may extend past 100% of the NTSC color gamut, a difference quite perceivable by the human eye.

In 2004, Hydis Technologies Co., Ltd licensed its AFFS patent to Japan"s Hitachi Displays. Hitachi is using AFFS to manufacture high end panels in their product line. In 2006, Hydis also licensed its AFFS to Sanyo Epson Imaging Devices Corporation.

A technology developed by Samsung is Super PLS, which bears similarities to IPS panels, has wider viewing angles, better image quality, increased brightness, and lower production costs. PLS technology debuted in the PC display market with the release of the Samsung S27A850 and S24A850 monitors in September 2011.

TFT dual-transistor pixel or cell technology is a reflective-display technology for use in very-low-power-consumption applications such as electronic shelf labels (ESL), digital watches, or metering. DTP involves adding a secondary transistor gate in the single TFT cell to maintain the display of a pixel during a period of 1s without loss of image or without degrading the TFT transistors over time. By slowing the refresh rate of the standard frequency from 60 Hz to 1 Hz, DTP claims to increase the power efficiency by multiple orders of magnitude.

Due to the very high cost of building TFT factories, there are few major OEM panel vendors for large display panels. The glass panel suppliers are as follows:

External consumer display devices like a TFT LCD feature one or more analog VGA, DVI, HDMI, or DisplayPort interface, with many featuring a selection of these interfaces. Inside external display devices there is a controller board that will convert the video signal using color mapping and image scaling usually employing the discrete cosine transform (DCT) in order to convert any video source like CVBS, VGA, DVI, HDMI, etc. into digital RGB at the native resolution of the display panel. In a laptop the graphics chip will directly produce a signal suitable for connection to the built-in TFT display. A control mechanism for the backlight is usually included on the same controller board.

The low level interface of STN, DSTN, or TFT display panels use either single ended TTL 5 V signal for older displays or TTL 3.3 V for slightly newer displays that transmits the pixel clock, horizontal sync, vertical sync, digital red, digital green, digital blue in parallel. Some models (for example the AT070TN92) also feature input/display enable, horizontal scan direction and vertical scan direction signals.

New and large (>15") TFT displays often use LVDS signaling that transmits the same contents as the parallel interface (Hsync, Vsync, RGB) but will put control and RGB bits into a number of serial transmission lines synchronized to a clock whose rate is equal to the pixel rate. LVDS transmits seven bits per clock per data line, with six bits being data and one bit used to signal if the other six bits need to be inverted in order to maintain DC balance. Low-cost TFT displays often have three data lines and therefore only directly support 18 bits per pixel. Upscale displays have four or five data lines to support 24 bits per pixel (truecolor) or 30 bits per pixel respectively. Panel manufacturers are slowly replacing LVDS with Internal DisplayPort and Embedded DisplayPort, which allow sixfold reduction of the number of differential pairs.

The bare display panel will only accept a digital video signal at the resolution determined by the panel pixel matrix designed at manufacture. Some screen panels will ignore the LSB bits of the color information to present a consistent interface (8 bit -> 6 bit/color x3).

With analogue signals like VGA, the display controller also needs to perform a high speed analog to digital conversion. With digital input signals like DVI or HDMI some simple reordering of the bits is needed before feeding it to the rescaler if the input resolution doesn"t match the display panel resolution.

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The worlds of high-end Color LCD Modules are taken over. As our world evolved and embedded devices becoming more, and more sophisticated and prevalent, we tend to look at the art of design. Steve Jobs sums it up just right. “Design is not just what it looks like and feels like. Design is how it works.” TFT LCD modules are a type of variant of an LCD which uses thin film, appliances such as: TV, computer monitors, kindles, mobile phone, and navigation system. The construction of a color LCD module or TFT LCD is quite extraordinary because of the circuit layout process; this form of layout is similar to the layout of a semiconductor product. Even though as we observe the TFT LCD display we came across few pros and cons which are most needed for this discussion. The advantages of TFT LCD are as follows: less energy consumption, visibility is sharper in other words has superb quality, physical design, response time, and less eye strain etc… With every great product there are few disadvantages associated, such as, cost and viewing angles.

TFT LCD displays are very convenient because of the energy consumption associate with this display, knowingly in today’s society saving energy is a number one priority to reduce greenhouse gas and ensure a better future generations. Due to the construction of TFT structures Pixel like materials does not consume much energy to begin with except this material consume far less power than a comparable CRT monitor. The images of a TFT display does not rely on the scanning of electron beams instead they are free from flicker and has a crisp image, with no geometric distortion. The physical design of TFT display are space savors which can be position anywhere in ones office, or house with a rotations mechanism in place for less constrains on space.

As mention before TFT LCD has few disadvantages, due to the nature of the design TFT LCD display may cost a little more than a regular monochrome display. Other disadvantages may arise when the viewing the display at the 6 0’clock direction but in fact the optimal viewing is at the 12’oclock direction this may also lead to inversion which or common in situation like this; however TFT displays are superior and will be in production for years to come.

Leveraging 50 years of presence in avionic cockpit lighting we provide the ultimate display solutions. Cevians has rapidly become the fastest-growing privately owned company offering fully customized TFT-LCDs. Our highly vertically integrated technological foundation, from material science, thin-film coatings, optical designs, electronics and electro-mechanical designs to system engineering, makes Cevians’ capabilities and product offerings truly unique and the natural partner for Tier 1 OEMs.

Understanding the diverse industry ecosystem, we offer the level of product that integrates perfectly in each customer’s base model, from supplying custom TFT-LCD to LCD modules, display head assemblies (DHA), and fully ruggedized display systems. This flexible strategy allows our customers to efficiently use their resources for core competencies.