tft lcd advantages and disadvantages free sample

TFT (Thin Film Transistor) LCD (Liquid Crystal Display) we are talking here is TN (Twisted Nematic) type TFT displays which is align with the term in the TV and computer market. Now, TFT displays have taken over the majority of low-end color display market. They have wide applications in TV, computer monitors, medical, appliance, automotive, kiosk, POS terminals, low end mobile phones, marine, aerospace, industrial meters, smart homes, consumer electronic products etc. For more information about TFT displays, please visit our knowledge base.

Talking about Pros and Cons of TFT displays, we need to clarify which display they are compared to. To some displays, TFT displays might have advantages, but compared with another display, the same character might become the disadvantages of TFT displays. We will try our best to make clear as below.

Less Energy Consumption: Compared with CRT(Cathode-Ray Tube) VFD ( Vacuum Fluorescent Display) and LED (Light Emitting Diode) display, which made laptop possible.

Excellent physical design. TFT displays are very easy to design and integrated with other components, such as resistive and capacitive touch panels (RTP, CTP, PCAP) etc.

Minimum Eye Strain: Because TFT panel itself doesn’t emit light itself like CRT, LED, VFD. The light source is LED backlight which is filtered well with the TFT glass in front for the blue light.

More Energy Consumption: Compared with monochrome displays and OLED (PMOLED and AMOLED) display, which makes TFT displays less attractive in wearable device.

Poor response time and viewing angle: Compared with IPS LCD displays, AMOLED displays and recent micro-LED display. TFT displays still need to note viewing angle of 6 o’clock or 12 o’clock in the datasheet and still have the gray scale inversion issue.

High tooling cost: Depending on which generation production line to produce and also depending on its size. Building a TFT display fab normally need billions of dollars. For a big size display which needs high generation production line to produce. The NRE cost can be millions dollars.

Sunlight Readability: Because it is very expensive to produce transflective TFT LCD displays, in order to be readable under the sunlight, very bright LED backlight (> 1,000 nits) has to be used. The power needed is high and also need to deal with heat management. If used together with touch panel, expensive optical bonding (OCA or OCR) and surface treatment (AR, AF) technologies have to be used.

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.

Responsible for performing installations and repairs (motors, starters, fuses, electrical power to machine etc.) for industrial equipment and machines in order to support the achievement of Nelson-Miller’s business goals and objectives:

• Perform highly diversified duties to install and maintain electrical apparatus on production machines and any other facility equipment (Screen Print, Punch Press, Steel Rule Die, Automated Machines, Turret, Laser Cutting Machines, etc.).

• Provide electrical emergency/unscheduled diagnostics, repairs of production equipment during production and performs scheduled electrical maintenance repairs of production equipment during machine service.

TFT stands for thin-film transistor, which means that each pixel in the device has a thin-film transistor attached to it. Transistors are activated by electrical currents that make contact with the pixels to produce impeccable image quality on the screen. Here are some important features of TFT displays.Excellent Colour Display.Top notch colour contrast, clarity, and brightness settings that can be adjusted to accommodate specific application requirements.Extended Half-Life.TFT displays boast a much higher half-life than their LED counterparts and they also come in a variety of size configurations that can impact the device’s half-life depending on usage and other factors.TFT displays can have either resistive or capacitive touch panels.Resistive is usually the standard because it comes at a lower price point, but you can also opt for capacitive which is compatible with most modern smartphones and other devices.TFT displays offer exceptional aspect ratio control.Aspect ratio control contributes to better image clarity and quality by mapping out the number of pixels that are in the source image compared to the resolution pixels on the screen.Monitor ghosting doesn’t occur on TFT displays.This is when a moving image or object has blurry pixels following it across the screen, resembling a ghost.

TFT displays are incredibly versatile.The offer a number of different interface options that are compatible with various devices and accommodate the technical capabilities of all users.

There are two main types of TFT LCD displays:· Twisted nematic TFT LCDs are an older model. They have limited colour options and use 6 bits per each blue, red, and green channel.

In-plane switching TFT LCDs are a newer model. Originally introduced in the 1990s by Hitachi, in-plane switching TFT LCDs consist of moving liquid pixels that move in contrast or opposite the plane of the display, rather than alongside it.

The type of TFT LCD monitor or industrial display you choose to purchase will depend on the specifications of your application or project. Here are a few important factors to consider when selecting an appropriate TFT LCD display technology:Life expectancy/battery life.Depending on the length of ongoing use and the duration of your project, you’re going to want to choose a device that can last a long time while maintaining quality usage.

Touch type and accuracy.What type of activities are you planning on using your device for? If it’s for extended outdoor use, then you should go with projected capacitive touch as this is more precise and accurate. Touch accuracy is important for industrial and commercial applications.

Image clarity.Some TFT displays feature infrared touchscreens, while others are layered. The former is preferable, especially in poor lighting conditions or for outdoor and industrial applications, because there’s no overlay and therefore no obstructions to light emittance.

The environmental conditions make a difference in operation and image clarity. When choosing a TFT for outdoor or industrial applications, be sure to choose one that can withstand various environmental elements like dust, wind, moisture, dirt, and even sunlight.

As a leading manufacturer and distributor of high-quality digital displays in North America, Nauticomp Inc. can provide custom TFT LCD monitor solutions that are suitable for a multitude of industrial and commercial indoor and outdoor applications. Contact us today to learn more.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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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.

The transmittance of a pixel of an LCD panel typically does not change linearly with the applied voltage,sRGB standard for computer monitors requires a specific nonlinear dependence of the amount of emitted light as a function of the RGB value.

In-plane switching was developed by Hitachi Ltd. in 1996 to improve on the poor viewing angle and the poor color reproduction of TN panels at that time.

Initial iterations of IPS technology were characterised by slow response time and a low contrast ratio but later revisions have made marked improvements to these shortcomings. Because of its wide viewing angle and accurate color reproduction (with almost no off-angle color shift), IPS is widely employed in high-end monitors aimed at professional graphic artists, although with the recent fall in price it has been seen in the mainstream market as well. IPS technology was sold to Panasonic by Hitachi.

It achieved pixel response which was fast for its time, wide viewing angles, and high contrast at the cost of brightness and color reproduction.Response Time Compensation) technologies.

Less expensive PVA panels often use dithering and FRC, whereas super-PVA (S-PVA) panels all use at least 8 bits per color component and do not use color simulation methods.BRAVIA LCD TVs offer 10-bit and xvYCC color support, for example, the Bravia X4500 series. S-PVA also offers fast response times using modern RTC technologies.

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 statements are applicable to Merck KGaA as well as its competitors JNC Corporation (formerly Chisso Corporation) and DIC (formerly Dainippon Ink & Chemicals). All three manufacturers have agreed not to introduce any acutely toxic or mutagenic liquid crystals to the market. They cover more than 90 percent of the global liquid crystal market. The remaining market share of liquid crystals, produced primarily in China, consists of older, patent-free substances from the three leading world producers and have already been tested for toxicity by them. As a result, they can also be considered non-toxic.

Kawamoto, H. (2012). "The Inventors of TFT Active-Matrix LCD Receive the 2011 IEEE Nishizawa Medal". Journal of Display Technology. 8 (1): 3–4. Bibcode:2012JDisT...8....3K. doi:10.1109/JDT.2011.2177740. ISSN 1551-319X.

K. H. Lee; H. Y. Kim; K. H. Park; S. J. Jang; I. C. Park & J. Y. Lee (June 2006). "A Novel Outdoor Readability of Portable TFT-LCD with AFFS Technology". SID Symposium Digest of Technical Papers. AIP. 37 (1): 1079–82. doi:10.1889/1.2433159. S2CID 129569963.

Kim, Sae-Bom; Kim, Woong-Ki; Chounlamany, Vanseng; Seo, Jaehwan; Yoo, Jisu; Jo, Hun-Je; Jung, Jinho (15 August 2012). "Identification of multi-level toxicity of liquid crystal display wastewater toward Daphnia magna and Moina macrocopa". Journal of Hazardous Materials. Seoul, Korea; Laos, Lao. 227–228: 327–333. doi:10.1016/j.jhazmat.2012.05.059. PMID 22677053.

The digital age has ushered in a whole host of new display technologies. The TFT LCD screens they are one of those technologies that have revolutionized the electronic device industry in recent years. These new displays have made it possible for manufacturers to deliver innovative user interfaces, fast response times, and sharp images on a wide variety of devices, from TVs to smartphones and everything in between.

This article will guide you in the world of TFT LCD screens. TFT stands for Thin Film Transistor Liquid Crystal Display (thin-film transistor liquid crystal display), while LCD refers to its general use in most electronic devices such as televisions, computer monitors, and projectors, among others. If you"re familiar with the basics of these display technologies, you"re halfway there.

A TFT LCD screen is athin film transistor electronic display (TFT). This means that just like a normal LCD screen, this screen also uses a liquid crystal material. However, the key difference between a typical LCD and a TFT LCD is the way the liquid crystal material is used in a TFT LCD. Unlike a normal LCD screen, which works by turning the voltage across the liquid crystal material on and off, a TFT has a digital control circuit. This switch-type control allows the screen to display images, including text and graphics.

active matrix: Active matrix TFT LCD displays use a thin layer of liquid crystal material sandwiched between two layers of thin transparent electrodes. A thin transparent conductive film is inserted between these electrodes and acts as a switch. When a voltage is applied across these electrodes, the liquid crystal material is forced to change its polarization state, causing a change in its optical properties. This property is used to turn pixels on and off to produce an image.

Passive matrix: In passive matrix TFT LCD displays, the liquid crystal panel is sandwiched between two glass plates. When a voltage is applied between the two electrodes of the glass, the electrodes change to conductive states and the liquid crystal changes from one state to another. In this way, the pixels are controlled by the panel itself.

good soda rate: Refresh rate refers to the speed at which a digital screen can display new images. For example, most CRT televisions display images at a refresh rate of 60 Hz. This means that the image displayed on the screen is updated 60 times per second. With new technologies, such as LCDs, this refresh rate has been reduced to 244 Hz, which means that the images displayed on the screen are refreshed only 244 times per second. In most cases, a refresh rate of at least 60 Hz is needed to deliver acceptable image quality. A screen with a refresh rate lower than that looks jagged and blurry.

Wide viewing angle: Unlike CRT televisions that display images with a narrow viewing angle, modern LCDs are capable of displaying images with a wide viewing angle. This means that you can view the images with your colleagues and friends from a wide angle without the image quality being affected.

Compact size: Being flat, the size is much more compact and thin compared to a CRT screen. Also, CRTs don"t usually come in such a wide variety of sizes, both the big ones and the smaller ones are just for LCDs.

Cost: The main advantage of an LCD screen is its low production cost. Compared to the production cost of a TFT, an LCD costs less, making it a more accessible display technology for the masses. However, there have recently been a number of advances in microlens technology that have made it possible to manufacture high-quality displays at a relatively low production cost.

As you can see, they are not overly expensive and allow you to carry out many projects with Arduino. And not only that, you can also join them to other different projects, including SBCs like the Raspberry Pi. Versatility is very high, the limit is your imagination.

TFT LCD display with touchscreen capabilities allow for more streamlined operations. It is being used in more and more areas. There arefive types of touchscreen technologies, offering benefits and limitations, namely in the areas of cost, picture quality, touch sensitivity and durability.

Touch type - TFT touchscreens discussed earlier have distinct advantages and disadvantages. Choice is hence a compromise, by weighing pros against cons. Projected capacitive touch is ideal for harsh, industrial and outdoor applications. IR type will not be a good fit for such applications. However, if clarity if important, then IR type touchscreen will be a good selection.

Accuracy of touch - This is the capability of providing reliable touch performance in devices when the TFT touchscreen is subjected to surrounding electric or magnetic noise. User must be able to correctly select target on screen without accidentally touch adjacent object.

Touchscreen resolution - Here we refer to the number of active touch-point and simultaneous touch-point supported by TFT touchscreen. This affects pointing precision and selection errors. A higher resolution screen provides additional touch-points and greater pointing.

Response time - The shorter time a TFT touchscreen responds to a touch, the better user would feel about the touchscreen. Research shows that humans need less than 10ms to feel comfortable a touch response. SAW touchscreen has the shortest response time, about 10ms. Whereas IR has a higher response time of around 20ms.

Clarity- Touchscreens are normally attached on top of the TFT LCD. So there is loss of light and affect clarity of image. IR touchscreen has no overlay, hence its transmission is 95% ~ 100%, clarity is the best among all the touchscreen solutions. Resistive type has the lowest rating in this area.

Environment- Selection of TFT touchscreen is also based on the product"s deployment environment. If the TFT touchscreen working environment is in outdoor and harsh conditions, then the selection should be focused on the type that can withstand dust, temperature, moisture, etc.

Life expectancy - In an actively used situation, TFT touchscreen"s degradation in performance is expected. Longevity of IR touchscreen is about five years, capacitive type has a shorter life of around two years.

There are many factors to consider in the proper selection of a touchscreen, primarily on the application and the environment in which it will be used. If you need more information on choosing a touch screen technology that best suits your project, feel free to leave us a message by clicking "Contact us" button below.

LCD stands for liquid crystal display. Liquid crystal is a kind of material that is neither liquid nor a solid, it comes in between these two states of matter. It has properties similar to that of the crystallised solid. The arrangement of molecules is in a fixed pattern however they are not fixed in shape or form.

They are usually found in smartphones, televisions, computer monitors and instrument panels and use a liquid crystal display panel to control where the light is displayed on your screen.

In LCD displays, light emitted from the backlight passes via a vertical polarisation filter after going through the liquid crystal element, this liquid crystal element twists this light wave. The vertically polarised light then turns to a horizontally polarised light. This horizontally polarised light passes via the horizontal polarisation filter allowing the passage of light. Hence the light is visible to us. The voltage we apply to the LCD is applied in such a way that the crystal mechanism of the light is removed and the light acquires a straight pattern. Due to this, the vertically polarised light will come out vertically only, however, the horizontally polarised light will be blocked and we won’t see any light in this case. This is how LCD works on the principle of blocking light.

3The fluorescent lights in an LCD TV are always placed behind the screen.The placements of the lights on an LED TV can differ which means light-emitting diodes can be placed either behind the screen or around its edges.

7LCD TVs are the most efficient type of TVs as can help you save as much as 30-70% more electricity than any other TV type.LED TVs consume very little energy so there is almost a 50% reduction in power consumption.

8LCD TVs use the cold cathode fluorescent lamps (CCFL) for backlighting. The picture quality of LCD TV is noticeable in scenes with high contrast, as the dark portions of the picture may appear too bright or washed out.LED TVs to use energy-efficient light-emitting diodes for backlighting and can provide a clearer, better picture, a thinner panel, and lesser heat dissipation than a customary LCD TV.

With the increasing popularity of smartphones and tablet computers, touch has become one of the most common user interfaces encountered today. For our final project design we have converted a number of open-source C++ libraries to C in order to interface with an LCD and touch screen via the Atmel ATmega644 microcontroller. In addition to these new libraries we included three pieces of software: a free drawing mode, a game called Yellow which pays homage to the arcade game Pac-Man© developed by Namco in 1980, and the classic pencil and paper game Tic-Tac-Toe. Each piece of software serves to demonstrate some of the many capabilities of the LCD and touch screen combination.

Our goal for the final project was to provide the ECE 4760 course with an easy to setup and cheap touch screen interface to be used with the Atmel ATmega644 microcontroller. While researching ways to implement this, we found the tutorial for an Arduino-based touch screen provided by LadyAda. The resulting C libraries that we created for our device are based upon the open-source C++ libraries provided in the tutorial.

We opted to display images with an LCD screen rather than using a CRT monitor due to the onboard memory of LCD screens. This means that the entire screen does not need to be refreshed when displaying a new image. This severely reduces the amount of overhead required by the CPU to update the screen.

The touch screen used in our project uses resistance rather than capacitance to sense touch. Resistive touch screens consist of two plastic sheets covered with a resistive coating separated by a very thin gap of air. Each sheet contains vertical and horizontal lines that allow for precise location measurement when they come in contact with the lines of the opposite sheet. Resistive touch screens have a number of advantages and disadvantages when compared to capacitive screens. The major benefit for us, due to the limited budget of the project, is the reduced cost. Resistive screens are also highly resilient to liquid damage, and so are widely used in restaurants and hospitals where liquid hazards are more common. The major disadvantage is the need for pressure in order to sense touch. This means that the screen can be easily scratched if the user is using a sharp object as a stylus. For this reason, we recommend using a plastic protective cover to mitigate damage to the screen.

Many of the touch screen design patents that were filed during the 1970s and 1980s have since expired. Therefore, use of touch screens and different designs are no longer hindered by potential patent infringements. Software patents for touch screens such as multiple input sensing and page scrolling do exist, but our project does not implement any of these methods and so is not in violation of the owners" intellectual property.

The only hardware used for this project is the protoboard with an ATmega644 and a TFT LCD with resistive touch screen purchased from Adafruit. The LCD is a 2.8" 320x240 pixel resolution screen with an attached resistive touch screen. A built in linear regulator allows the screen to be used with either 5V or 3.3V logic. The wiring was done using a tutorial from LadyAda. The LCD screen has four control lines, eight data lines, a reset pin, a backlight pin, four pins for the touch screen, VCC and ground. VCC is connected to 5V from the MCU and ground is connected to MCU ground. The backlight should always be on, so it is simply connected to VCC. It is possible to use a PWM signal to dim the backlight, but that was not necessary for this project.

The four control signals are chip select, command/data, write, and read. They are connected to pin C0, pin C1, pin C2, and pin C3, respectively. The chip select pin is held low for the duration of register reads and writes and when a command or data is being written. Immediately following the read or write the pin is set back to high. The command/data pin is set low while writing a command or writing a register. It is kept high while writing data or reading data from the LCD. Once the command or register is finished being written, the command/data pin is set high again. When writing a register or data to the LCD, the data is written eight bits at a time. First, the eight data lines are set to their appropriate values using the write8 function. The write pin is set low and then immediately set high. If 16 bits of data need to be written, the write8 function is called again for the second 8 bits. The write pin is then toggled again to write the data. When reading data from the LCD, the read pin is toggled low and the data is read using the function read8. Once the bits are read, the read pin is set high again. If more bits need to be read, the read pin is set low and the next eight bits are read. Once finished, the read pin is set high again.

The eight data pins are connected to pins B0, B1, and D2-D7. D0 and D1 are left unconnected so that serial communication can still be used. The data pins are bidirectional; they are set to outputs when writing data and inputs when reading data. This is achieved using the setWriteDir and setReadDir functions.

The reset pin is active high. It is connected to pin C4. It is left high for the duration of the operation of the LCD screen and is only set low when the program first starts in order to reset the LCD controller chip.

The four pins for the resistive touch screen are Y+, Y-, X+, and X-. Y+ is connected to pin A0, X- is connected to A1, X+ is connected to A2, and Y- is connected to A3. The X position on the touch is determined by setting Y+, Y-, and X- to ground and X+ to high. The voltage on Y+ is then read. To get the most accurate position, the 10-bit ADC result from the microcontroller is used. This requires reading the low bits first and then reading the high bits and concatenating the results. The final raw x position returned is the 10-bit ADC result subtracted from 1023. The Y position is determined in a similar way. This time the X+, X-, and Y- pins are grounded and the Y+ pin is set high. The voltage on the X- pin is then read.

As this is a resistive touch screen, the pressure must be measured to determine if someone is actually pressing on the screen. This is accomplished by setting X+, X-, and Y+ to ground and Y- high. First the voltage across X- is read, then the voltage across Y+. The pressure is determined using the following equation:

The software for this project is based off of the open-source libraries released by Adafruit. There are three libraries: TFTLCD, TouchScreen, and Adafruit_GFX. These libraries are written for Arduino microcontrollers and are in C++. Converting the libraries to C involved removing the classes and converting all of the functions to static functions. The libraries also contained a large number of Arduino specific functions. These functions were manually replaced with code that performs the same functionality, but that works on the ATmega644. The touch screen libraries were initially using PORTC as inputs to the ADC. However, since the input to the ADC on the ATmega644 is PORTA, this had to be changed. To see the mapping of all of the pins, refer to the hardware section. To make it easier for future students to use, the converted libraries are located in separate C files from the programs we wrote. The TFT LCD and Adafruit_GFX libraries have been combined into a single C file. A few additional functions were added to the libraries. These include the map function which is included in the Arduino software package. This function remaps a number from one range to another. Additional drawing functions added include the ability to draw half a circle and the ability to draw strings instead of individual characters. Comments were also added to the header files to allow the user to quickly understand what a function does and what the appropriate inputs are.

To showcase the capabilities of the touch screen and LCD, three simple programs were written. The first is a simple drawing program based off an example provided with the TFT LCD library. The second is a Tic-Tac-Toe game which allows the player to draw X"s on their turn. The final program is Yellow. Yellow is a simple demonstration that draws its inspiration from the popular arcade game Pac-Man©, created by Namco in 1980.

When the user first turns on the ATmega644 they are presented by the main menu. This menu contains the title, three virtual buttons, and instructions about how to get back to the main menu from each program.

The menu was created by first filling the entire screen black using the fillScreen function. Then three grey boxes are drawn in the middle of the screen to make the "buttons" using the fillRect function. Next, the text is drawn using the drawString function. Once the menu is drawn, the program waits in an infinite while loop for user input. On each iteration of the loop the program gets the x and y position from the touch screen as well as the pressure.

Since we are using a resistive touch screen, a threshold pressure must be used in order to determine if the user is actually touching the screen or if it is just noise. The pressure values we considered were between 250 and 750. When a valid pressure is detected, the program then determines where the user is touching. The x and y values read from the touch screen must first be mapped to the resolution of the LCD to give a useful x-y position. This is done using the map function which is provided by Arduino. The program checks the x and y position against the boundaries of each "button." If the user touches within a "button," then the program calls the function to launch the appropriate program. As indicated by the message at the bottom of the menu, the user can return to the main menu from any program by simply touching the very top of the LCD screen. When the user touches the top of the LCD screen, the running program will detect this touch, return to main and the main menu will be redrawn. The positioning of the text and "buttons" on the menu was determined by estimating the appropriate position given the resolution of the screen and then doing a bit of guess and check positioning.

The left two buttons will increase and decrease the size of the drawing pen. This is indicated by putting a small circle in the left square and a large circle in the right square. The circles were drawn using the fillCircle function. The middle two buttons are used as erasers. The left button will clear the entire drawing; it is indicated with an "X". This works by filling the drawing area with black using the fillRect function. The right button changes the pen to an eraser. This is indicated by an "E." The eraser simply turns the user"s pen black. The size of the eraser can be increased and decreased in the same way the pen size is changed.

There are twenty-four different colors the user can choose from. These colors are split into four groups of six colors. When the free draw program starts, the first set of colors is displayed. The currently selected color is indicated by having a white border around it. When the user touches a different color, the pen color changes and the white border is moved to the selected color. The right two buttons on the screen allow the user to scroll between different sets of colors. The buttons are indicated by the "<" and ">" characters. Pressing one of these buttons changes the state which will then redraw the colored squares at the top of the screen to represent the colors available in the selected set. The colors in each set are generically defined at the top of the C file in the format SXCY where X represents the color set (0-3) and Y represents the color number in the set (1-6). Changing a particular color in the set is as simple as changing the defined value.

When any of the buttons are touched, the touched button will be momentarily be surrounded by a blue border to give the user visual feedback. This is achieved by using the drawRect function. This function is similar to the fillRect function except it only draws the border and therefore is much quicker to update.

Tic-Tac-ToeThe Tic-Tac-Toe program starts similarly by first using the fillScreen function to clear the screen. Next the program draws the text for the score keeping using the drawString function. Two grey "buttons" are drawn using the fillRect function so the user can change between easy and hard difficulty. Finally, the grid is drawn using the drawLine function.

Once the screen is initialized, the program waits for user input. To make a move, the user draws an "X" into a chosen square. The function detects an "X" when the user draws twice in the same square. When the program detects a touch in a square, it increments the touched variable. This variable is kept at a constant value until the user stops touching the screen; at which point touched is incremented again. When the user touches that same square again touched is incremented a third time. Finally, when the user stops touching the screen, the "X" is considered done. When a square is occupied, the player is prevented from drawing in that square. The game ends when the player wins, the CPU wins, or there are no more unused spaces left. If a win has occurred, a white line is drawn across the winning moves to indicate the victory. The squares are then cleared and the grid is redrawn. Finally, the appropriate score is updated and redrawn. For each game the player and CPU alternate who starts.

The game can be played with two difficulty modes: easy and hard. Easy mode is segmented into two versions. The first is when the CPU has the first move of the game. In this case, the CPU simply chooses a random unused space in the 3x3 grid. This makes beating the computer quite trivial, but serves as a nice introduction to using the touch screen to place a player"s moves. If the player starts the game, the CPU will make much more strategic moves. The CPU starts by seeking a victory in the next move. If this is not possible, it will determine if it can block the user from a victory. If neither of these is the case, then the CPU will choose a random unused space to occupy.

For the hard mode of Tic-Tac-Toe, we have implemented a computer opponent which will always choose the correct move. This results in the game ending in a tie or a computer victory. The logic is implemented in two different state tables: one for when the CPU player makes the first move and a second for when the human player makes the first move. For the first table we used the following image from Brent Yorgey:

The image shows the optimal move (represented by a red X) to counter each of the opposing player’s moves. To read the image, start with the outermost 3x3 grid. Based on the largest red X, the best first move to make is in the bottom right corner (or any of the corners, really, and then translating the elements of the grid as necessary). Then, go to the square that the opposing player chose to use. This square now represents the current 3x3 grid, and the red X shows where to place the optimal move. This process is repeated until the game ends in a tie or the CPU wins.

A nine-element array, used, is declared to store whether a space in the grid is occupied or free. If the space is occupied by the human player, then that index of the array is given a value of 1. If the space is occupied by the computer, then the value in the array is set to 2. In easy mode, the computer looks for an unoccupied space by randomly picking a number between 0 and 8, and then checking the corresponding index of used. If the space is occupied, the computer picks another random space until it finds a free one. This code can be seen below:

For hard mode, a second nine-element array, user, is initialized to track where the human player moves on each of his/her turns. The index of the array represents the space in the 3x3 grid occupied by the human player, and the value represents on what turn the player moved there. The value is 0 if the player is not occupying that space. For example, consider the following sequence of moves by the human player:

This sequence of code says that if the human player is at their second move, and they occupied the upper left corner of the game grid on their first move, then the CPU should occupy the middle of the grid. Statements such as these are iterated until every possible game scenario is covered. The full code can be viewed in the Appendix.

The final program is Yellow. The motivation behind Yellow was to show the capabilities and limitations of the LCD in terms of animation. Yellow is a limited-feature "game" that draws inspiration from Pac-Man©. Yellow must move around the level and eat all of the yellow circles. The user controls Yellow by swiping their finger or a stylus across the screen in the direction they want Yellow to move.

The level is drawn using the drawLine function. Placement of the lines involved a tedious combination of careful planning and guess and check work. Yellow himself is a two-step animation. The first step involves drawing a yellow circle using the fillCircle function. Then a black line is drawn for his mouth. On the second animation step, a black triangle is drawn so that is looks as if Yellow"s mouth is open. This two steps are repeated to c