difference between tft lcd led monitors free sample

In market, LCD means passive matrix LCDs which increase TN (Twisted Nematic), STN (Super Twisted Nematic), or FSTN (Film Compensated STN) LCD Displays. It is a kind of earliest and lowest cost display technology.

LCD screens are still found in the market of low cost watches, calculators, clocks, utility meters etc. because of its advantages of low cost, fast response time (speed), wide temperature range,  low power consumption, sunlight readable with transflective or reflective polarizers etc.  Most of them are monochrome LCD display and belong to passive-matrix LCDs.

TFT LCDs have capacitors and transistors. These are the two elements that play a key part in ensuring that the TFT display monitor functions by using a very small amount of energy without running out of operation.

Normally, we say TFT LCD panels or TFT screens, we mean they are TN (Twisted Nematic) Type TFT displays or TN panels, or TN screen technology. TFT is active-matrix LCDs, it is a kind of LCD technologies.

TFT has wider viewing angles, better contrast ratio than TN displays. TFT display technologies have been widely used for computer monitors, laptops, medical monitors, industrial monitors, ATM, point of sales etc.

Actually, IPS technology is a kind of TFT display with thin film transistors for individual pixels. But IPS displays have superior high contrast, wide viewing angle, color reproduction, image quality etc. IPS screens have been found in high-end applications, like Apple iPhones, iPads, Samsung mobile phones, more expensive LCD monitors etc.

Both TFT LCD displays and IPS LCD displays are active matrix displays, neither of them can produce color, there is a layer of RGB (red, green, blue) color filter in each LCD pixels to make LCD showing colors. If you use a magnifier to see your monitor, you will see RGB color. With switch on/off and different level of brightness RGB, we can get many colors.

Neither of them can’t release color themselves, they have relied on extra light source in order to display. LED backlights are usually be together with them in the display modules as the light sources. Besides, both TFT screens and IPS screens are transmissive, it will need more power or more expensive than passive matrix LCD screens to be seen under sunlight.  IPS screens transmittance is lower than TFT screens, more power is needed for IPS LCD display.

Confused about LED vs. LCD vs. TFT? Here"s everything you need to know. Creating or upgrading a device display or screen can involve a lot of different things, but it often comes down to one major question - what kind of display should you get?

So, there are 3 common displays LED, LCD and TFT available in the market. All terms refer to the flat-panel display, or screen, of a computer monitor or television set. In this article, we are going to differentiate between them. It will help you to choose a better one.

LCD stands for liquid crystal display. Works by adjusting the amount of light blocked. Usually has a backlight but might not (clocks, calculators, Nintendo Gameboy). The green-black ones can be very cheap and are a mature technology. Response time can be slow. An LCD display uses the light balancing qualities of crystals. Today LCDs are used in a great number of products and applications. Your TV, computer screen, calculator, cell phone and the dreaded alarm clock are all made of an LCD flat panel. Color LCDs produce the color based on two techniques: Passive matrix and active matrix. Passive matrix is the cheapest technology of the two. The other technology is called an active matrix or TFT. Active matrix displays produce really sharp and clear images.

This is a type of LCD with a thin film transistor attached to each pixel. All computer LCD screens are TFT since the early 2000s; older ones had slower response times and poorer color. Cost is now very good; power consumption is fairly good but dominated by the backlight. Has to be manufactured out of glass. The TFT layer is embedded in the screen itself, it reduces crosstalk between pixels. Crosstalk happens when a signal sends to a pixel also affects the pixel next to it. This makes the TFT technology the technology offering the best resolution and image quality. It also makes it a bit more expensive. Today TFTs have become the standard when producing LCD screens.

LED stands for a light emitting diode. As the name suggests, emits light rather than blocking it like LCD. Used for red/green/blue/white indicator lights everywhere. Some manufacturers advertise "LED" displays that are TFT screens with a white LED backlight, which is just confusing. Ones that are real LED screens are usually OLED.

Some devices actually have backlights made from Red, Green and Blue LEDs, normally referred to as RGB LED, which tend to have better color reproduction than any other display.

LED screen is just like saying that it is a plastic screen. You still have the WHOLE screen illuminated all the time and LED is "good" only for being more eco-friendly and probably more bright at max setting if you ever need this.

An LCD panel is, in fact, 2 layers of glass with some volume of Liquid Crystal in between. These two form the panel itself. The 2 layers are usually called Color Filter Glass (above) and TFT glass (below).

LCDs can’t completely prevent light from passing through, though, even during dark scenes, so dimming the light source itself aids in creating deeper blacks and more impressive contrast in the picture.

A standard TFT has a whole "lamp" behind it, illuminating the whole screen all the time. This way, you cannot have a true black, as it is still illuminated and stay grayish.

TFTs are a type of active matrix display that controls individual pixel updates several times per second on the screen to update the image relative to the content source.

TFT displays use more electricity than regular LCD screens, so they not only cost more in the first place, but they are also more expensive to operate.

LCDs use fluorescent lights while LEDs use those light emitting diodes. The fluorescent lights in an LCD are always behind the screen. On an LED, the light emitting diodes can be placed either behind the screen or around its edges.

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.

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.

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.

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.

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.

LCD: liquid crystal display. Works by adjusting the amount of light blocked. Usually has a backlight but might not (clocks, calculators, Nintendo Gameboy). The green-black ones can be very cheap and are a mature technology. Response time can be slow.

TFT: is a type of LCD with a thin film transistor attached to each pixel. All computer LCD screens are TFT since early 2000s; older ones had slower response times and poorer colour. Cost is now very good; power consumption is fairly good but dominated by the backlight. Has to be manufactured out of glass.

LED: light emitting diode. As the name suggests, emits light rather than blocking it like LCD. Used for red/green/blue/white indicator lights everywhere.

Some manufacturers advertise "LED" displays that are TFT screens with a white LED backlight, which is just confusing. Ones that are real LED screens are usually OLED.

OLED: organic LED (rather than silicon or germanium based like regular LEDs). Comparatively recent technology, so cost still quite variable and not available in really large sizes. In theory can be printed on plastic, resulting in lighter flexible displays with good brightness, good power consumption and good response time.

TFT displays are also known as an “Active Matrix TFT LCD module” and have an array of thin film transistors fabricated on the glass that makes the LCD. There is one of these transistors for each pixel on the LCD. See our blog post RGB and Color Depth for more on how TFTs show color.

LCDs use voltage applied to a field of microscopic liquid crystals to change the crystal’s orientation. The orientation of the crystals changes the polarization of the liquid crystal creating light or dark pixels on the display.

Beautiful, complex images: All of our TFT modules are full-color graphic displays. Unlike standard monochrome character displays, you can create complex images for an imaginative user experience.

Single Supply: Most of the TFTs use an integrated controller with built-in voltage generation so only a single 3.3v supply is needed for both the panel power and logic voltage.

Many of our character LCD modules use a standard HD44780 compatible controller, so they can be quickly integrated into a new product or used as a replacement in your existing products.

Many of the LCD controllers on board our graphic LCD display modules also include a CGROM (character generator ROM) which allows for easy character information as well as full bit-mapped graphic information to be shown.

Some of the graphic LCD displays have the ability to render graphics in grayscale, enabling you to show images and elements of your UI (user interface) with more depth and definition.

Because OLEDs are emissive, these displays can always be used in dark environments. There is usually a software command or hardware setting that will allow OLEDs to be dimmed.

Some OLED displays are bright enough to be sunlight readable–these models will typically take more current and may have a shorter rated lifetime. Additionally, OLEDs have extremely wide viewing angles.

What makes OLEDs useful for display construction is that they can be fabricated in bulk. Using OLED fabrication techniques, all the diodes can be made at the same time, at a much lower cost. OLEDs also come in a wide variety of colors.

For years, TFT displays have been the dominating technology in visualization. TFT LCD displays are everywhere in our daily lives; in consumer electronics, health care, communication devices and industry applications. While there are many LCD products in the market, they are not always suitable for every application. This is especially true for industrial TFT LCD. Understanding different requirements between industrial display and consumer TFT LCD, will help determine the best TFT LCD for your application.

Consumer grade TFT LCD like cell phone screen and computer monitor occupy big chunk of LCD market. Due to the nature of consumer market, competitive pricing and quick production cycles, these TFT LCDs are lack of the durability that industrial LCD has. Not like our cell phone screen and computer monitor, industrial LCD displays are used in much challenging environments. For example, an TFT LCD display on production line will face constant vibration, high working temperature. Its endurance to outside condition is a must.

Industrial TFT LCD has very good visibility. Which includes wide viewing angle, so that staff on production line can easily read information from different angles.

Sunlight readable is another important aspect that industrial TFT LCD persists. Many industrial applications are used outdoor, under direct sunlight. And user needs to be able to read what is on LCD screen easily. Topway has years experience on producing sunlight readable TFT LCD by using high brightness LED backlight and low reflectance technologies.

Industrial TFT LCD is made with high quality industrial grade components and material. Only then we could produce high quality TFT display that survives rigid tests like ESD, EMI and aging test, etc. All LCD product from Topway went through strict testings before reaching customers" warehouses.

Industrial TFT LCD has way longer supply commitment than consumer LCD. Ever try to fix a 2~3 years old cell phone"s crack screen? It is very difficult and expensive. Because replacement LCD screen is no longer being made. On the other hand, industrial LCD screen usually is in production for 10 plus years. And most of the time, for Topway anyway, there will be an upgrade model to replace end-of-life product. Thus, our customers won"t need to do much change on their product.

Industrial TFT LCD is a lot better in many areas than consumer one, even they look similar in normal situation. Topway as an industrial TFT LCD manufacturer, has been designing and producing industry grade LCD for more than twenty years. Our commitment on quality and customer service wins Topway friendship and orders. Please feel free to leave us message on your next industry project.

What are the key differences between leading electronic visual displays available in the market? Such are the times that we live in that today most of us cannot possibly imagine a life without an electronic device. In fact, we have managed to surround ourselves and depend on a growing number of electronic appliances. Several of these devices - as it happens - also have an electronic visual display; be it a mobile phone, a tablet, a desktop monitor or the television set. Without a doubt, these electronic screen devices have revolutionised the way we lead our lives now as all of the four devices have become increasingly commonplace to the point of becoming basic necessities. Which brings to our blog topic: what exactly is an electronic screen and which are the leading screen technologies available today? Read on to know more…

An electronic screen or an electronic visual display, informally called a screen, is basically a device used to display / present images, text, or video transmitted electronically, without creating a permanent record. As mentioned earlier, electronic visual displays include television sets, computer monitors, and digital signage in information appliances. As per the definition, an overhead projector (along with screen onto which the text, images, or video is projected) can also be called an electronic visual display.

1. Cathode Ray Tube (CRT) display:A vacuum tube containing one or more electron guns and a phosphorescent screen, the cathode-ray tube (CRT) is used to display images. It modulates, accelerates, and deflects electron beams onto the screen to make the images. The images could be electrical waveforms (oscilloscope), pictures (television, computer monitor) or radar targets. CRTs have also been used as memory devices, wherein the visible light from the fluorescent material (if any) does not really have any significant meaning to a visual observer, but the visible pattern on the tube face could cryptically represent the stored data. In television sets and computer monitors, the front area of the tube is scanned systematically and repetitively in a pattern called a raster. Thanks to the intensity of each of the three electron beams - one for each additive primary color (red, green, and blue) - being controlled with a video signal as a reference, an image is produced. In modern CRT monitors and TVs, magnetic deflection bends the beams; magnetic deflection is essentially a varying magnetic field generated by coils and driven by electronic circuits around the neck of the tube, although electrostatic deflection is often used in oscilloscopes, a type of electronic test instrument. CRT is one of the older screen/ display technologies.

2. Flat-Panel display: Flat-panel displays are electronic viewing technologies that are used to allow people to see content (still images, moving images, text, or other visual material) in a range of entertainment, consumer electronics, personal computer, and mobile devices, and several kinds of medical, transportation and industrial equipment. They are much lighter and thinner than traditional cathode ray tube (CRT) television sets and video displays and are typically less than 10 centimetres (3.9 in) thick. Flat-panel displays can be classified under two display device categories: volatile and static. Volatile displays need pixels to be periodically electronically refreshed to retain their state (say, liquid-crystal displays). A volatile display only shows an image when it has battery or AC mains power. Static flat-panel displays rely on materials whose color states are bistable (say, e-book reader tablets from Sony), and they retain the text or images on the screen even when the power is off. In recent times, flat-panel displays have almost completely replaced old CRT displays. Most flat-panel displays from the 2010s use LCD and/or LED technologies. Majority of the LCD screens are back-lit as color filters are used to display colors. Being thin and lightweight, flat-panel displays offer better linearity and have higher resolution than the average consumer-grade TV from the earlier decades. The highest resolution for consumer-grade CRT TVs was 1080i, whereas many flat-panels can display 1080p or even 4K resolution.

3. Plasma (P) display: A plasma display panel (PDP) is a type of flat panel display that uses small cells containing plasma; ionized gas that responds to electric fields. Earlier, plasma displays were commonly used in larger televisions (30 inches and larger). But since more than a decade now, they have lost almost all market share due to competition from low-cost LCDs and more expensive but high-contrast OLED flat-panel displays. Companies stopped manufacturing plasma displays for the United States retail market in 2014, and for the Chinese market in 2016.

So ELD then is a kind of flat panel display produced by sandwiching a layer of electroluminescent material between two layers of conductors. When the current flows, the layer of material emits radiation in the form of visible light. Basically, electroluminescence works by exciting atoms by passing an electric current through them, leading them to emit photons. By varying the material being excited, the color of the light being emitted is changed. The actual ELD is built using flat, opaque electrode strips running parallel to each other, covered by a layer of electroluminescent material, followed by another layer of electrodes, running perpendicular to the bottom layer. This top layer has to be transparent so as to allow light to escape. At each intersection, the material lights, creating a pixel.

5. Liquid Crystal Display (LCD): A liquid-crystal display (LCD) is a flat-panel display or other electronically modulated optical device that makes use of the light-modulating properties of liquid crystals. Liquid crystals do not give out light directly; they use a backlight or reflector to create images in color or monochrome. LCDs display arbitrary images like in a general-purpose computer display or fixed images with low information content, that can be displayed or hidden, such as preset words, digits, and seven-segment displays, like in a digital clock. They use the same core technology, apart from the fact that arbitrary images are made up of a large number of small pixels, while other displays have larger elements. LCDs could be on (positive) or off (negative), as per the polarizer arrangement. For instance, a character positive LCD with a backlight has black lettering on a background the same color as the backlight, and a character negative LCD has a black background with the letters matching the backlight color. Blue LCDs typically get their characteristic appearance from optical filters being added to white.

LCD screens are being used in several applications such as LCD televisions, computer monitors, instrument panels, aircraft cockpit displays, and indoor and outdoor signage. Small LCD screens are seen in portable consumer devices such as digital cameras, watches, calculators and mobile telephones, including smartphones. LCDs are also found in consumer electronics products such as DVD players, video game devices and clocks. It is interesting to note that these displays are available in a wide range of screen sizes as compared to CRT and plasma displays. Also, while LCD screens have replaced heavy, bulky cathode ray tube (CRT) displays in almost all applications, they are slowly being replaced by OLEDs, which can be easily made into different shapes, and boast other advantages such as having a lower response time, wider color gamut, virtually infinite color contrast and viewing angles, lower weight for a given display size and a slimmer profile and potentially lower power consumption. OLEDs, however, are more expensive for a given display size and they can suffer from screen burn-in when a static image is displayed on a screen for a long time (for instance, the table frame for an airline flight schedule on an indoor sign), not to mention that there is currently no way to recycle OLED displays. LCD panels, on the other hand, are susceptible to image persistence but they rarely suffer image burn-in as they do not use phosphors, plus they can be recycled, although this technology is not exactly common as yet. Not surprisingly, attempts have been made to increase the lifespan of LCDs in the form of quantum dot displays, which provide performance to that of an OLED display, but the Quantum dot sheet that gives these displays their characteristics can not yet be recycled. LCDs are also more energy-efficient and can be disposed of more safely than a CRT display.

6. Light-Emitting Diode (LED) display:An LED display is a flat panel display that uses an array of light-emitting diodes as pixels for a video display. Their brightness lets them be used outdoors where they are visible in the sun for store signs and billboards. It was in 1962 that LED diodes first came into being; this was when the first practical LED was invented by General Electric’s Nick Holonyak Jr. This was also when they were mainly red in color. While the early models had a monochromatic design, the efficient Blue LED completing the color triad became available in the market only in the late 1980s. Today, large displays use high-brightness diodes to generate a wide spectrum of colors. In fact, recently, LEDs have also become a popular choice among destination signs on public transport vehicles and variable-message signs on highways. LED displays can offer general illumination in addition to visual display, as when used for stage lighting or other decorative (as opposed to informational) purposes. Several big corporations such as Apple, Samsung and LG are currently looking to develop MicroLED displays. These displays are easily scalable, and help with making the production process more streamlined. That said, production costs continue to be quite high and thus remain a limiting factor.

7. Organic Light-Emitting Diode OLED display: An organic light-emitting diode (OLED), also called an organic EL (organic electroluminescent) diode, is a light-emitting diode (LED), where the emissive electroluminescent layer is a film of organic compound that gives out light in response to an electric current. The organic layer is located between two electrodes, at least one of which is transparent. OLEDs are used to build digital displays in devices such as television screens, computer monitors, portable systems such as smartphones, handheld game consoles and digital assistants. Typically, an OLED display works without a backlight because it emits visible light. This means that it can display deep black levels and can be thinner and lighter than a liquid crystal display (LCD). In low ambient light conditions, say in a dark room, an OLED screen can achieve a higher contrast ratio than an LCD, irrespective of whether the LCD uses an LED backlight or cold cathode fluorescent lamps.

Also important to note an OLED display can be driven with a passive-matrix (PMOLED) or active-matrix (AMOLED) control scheme. In the former, each row (and line) in the display is controlled sequentially, one by one, as opposed to in the AMOLED where a thin-film transistor backplane is used to directly control and switch each individual pixel on or off, thus offering higher resolution and larger display sizes.

Lastly, there are two main families of OLED: those based on small molecules and those making use of polymers. A big area of research is the development of white OLED devices for use in solid-state lighting applications.

8. Active-Matrix Organic Light-Emitting Diode (AMOLED) display: AMOLED (Active-Matrix Organic Light-Emitting Diode) is a display device technology being used in smartwatches, mobile devices, laptops, televisions, media players and digital cameras. As mentioned earlier, it is a type of OLED; rather a specific type of thin-film-display technology where organic compounds form the electroluminescent material. What distinguishes it from PMOLED is the active matrix technology behind the addressing of pixels. An AMOLED display basically comprises an active matrix of OLED pixels generating light (luminescence) upon electrical activation that have been positioned or integrated onto a thin-film transistor (TFT) array, which in turn operates as a series of switches to control the current flowing to each individual pixel. AMOLED technology has continued to work towards consuming low power, becoming low-cost and offering scalability (mainly by offering larger sizes.

9. Super AMOLED display: Super AMOLED is essentially an AMOLED display but it is a term coined for marketing purposes by leading device manufacturers. It is used to denote AMOLED displays that come with an integrated digitizer, i.e. the layer that detects touch is integrated into the screen, instead of overlaid on top of it. The display technology however is not an improvement on the AMOLED. For instance, Samsung claims that Super AMOLED displays reflect one-fifth as much sunlight as the first generation AMOLED. In fact, Super AMOLED displays that are part of the Pentile matrix family, are also at times known as SAMOLED. Other variations of this term include Super AMOLED Advanced, Super AMOLED Plus, HD Super AMOLED, HD Super AMOLED Plus and Full HD Super AMOLED.

10. Quantum Dot (QD) display:A quantum dot display is a display device that uses quantum dots (QD), basically semiconductor nanocrystals that can generate pure monochromatic red, green, and blue light. Photo-emissive quantum dot particles are used in a QD layer which converts the backlight to give out pure basic colors that in turn enhance display brightness and color gamut by decreasing light loss and color crosstalk in RGB color filters. This technology is used in LED-backlit LCDs, though it applies to other display technologies as well (such as white or blue/UV OLED).

Among devices employing QD screens, one can find electro-emissive or electroluminescent quantum dot displays, which are currently an experimental type of display based on quantum-dot light-emitting diodes (QD-LED). These displays are similar to active-matrix organic light-emitting diode (AMOLED) and MicroLED displays, as in light is produced directly in each pixel by applying an electric current to inorganic nano-particles. QD-LED displays are supposed to support large, flexible displays and not degrade as readily as OLEDs, making them good bets for flat-panel TV screens, digital cameras, mobile phones and handheld game consoles. As of 2018, all commercial products like LCD TVs that use quantum dots and are called QLED, use photo-emissive particles, whereas electro-emissive QD-LED TVs are only to be found in laboratories today.

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.

Red, Green and Blue (RGB) backlights are built with either a single LED that produces red, green and blue colors or with three separate Red, Green or Blue LEDs.

Backlight brightness (Luminance) is measured in nits. A nit being the amount of light that one candle delivers in a 1 square meter box. The intensity of the LED backlight can be critical when operating in low light or in direct sun light and is usually controlled by adjusting the DC voltage. In many applications this is accomplished through pulse-width modulation (PWM)

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.

Resistive touch panels are constructed using flexible materials with an air gap between and are coated with a resistive layer. When an object applies pressure to the top layer, it makes contact with microdots located on the bottom layer. This allows the touch screen to find the location of the touch using X and Y coordinates.

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”.

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).

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.

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 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.

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.

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.

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.

When the field is on, the liquid crystal molecules start to tilt towards the center of the sub-pixels because of the electric field; as a result, a continuous pinwheel alignment (CPA) is formed; the azimuthal angle rotates 360 degrees continuously resulting in an excellent viewing angle. The ASV mode is also called CPA mode.

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.

Backlight intensity is usually controlled by varying a few volts DC, or generating a PWM signal, or adjusting a potentiometer or simply fixed. This in turn controls a high-voltage (1.3 kV) DC-AC inverter or a matrix of LEDs. The method to control the intensity of LED is to pulse them with PWM which can be source of harmonic flicker.

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.

Click calculate to find the energy consumption of a 22 inch LED-backlit LCD display using 30 Watts for 5 hours a day @ $0.10 per kWh. Check the table below and modify the calculator fields if needed to fit your display.

LED & LCD screens use the same TFT LCD (thin film transistor liquid crystal display) technology for displaying images on the screen, when a product mentions LED it is referring to the backlighting. Older LCD monitors used CCFL (cold cathode fluorescent) backlighting which is generally 20-30% less power efficient compared to LED-backlit LCD displays.

The issue in accurately calculating the energy consumption of your tv or computer display comes down to the build quality of the screen, energy saving features which are enabled and your usage patterns. The only method to accurately calculate the energy usage of a specific model is to use a special device known as an electricity usage monitor or a power meter. This device plugs into a power socket and then your device is plugged into it, electricity use can then be accurately monitored. If you are serious about precisely calculating your energy use, this product is inexpensive and will help you determine your exact electricity costs per each device.

In general we recommend LED displays because they offer the best power savings and are becoming more cheaper. Choose a display size which you are comfortable with and make sure to properly calibrate your display to reduce power use. Enable energy saving features, lower brightness and make sure the monitor goes into sleep mode after 5 or 10 minutes of inactivity. Some research studies also suggest that setting your system themes to a darker color may help reduce energy cost, as less energy is used to light the screen. Also keep in mind that most display will draw 0.1 to 3 watts of power even if they are turned off or in sleep mode, unplugging the screen if you are away for extended periods of time may also help.

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.

In this Arduino touch screen tutorial we will learn how to use TFT LCD Touch Screen with Arduino. You can watch the following video or read the written tutorial below.

The next example is controlling an RGB LED using these three RGB sliders. For example if we start to slide the blue slider, the LED will light up in blue and increase the light as we would go to the maximum value. So the sliders can move from 0 to 255 and with their combination we can set any color to the RGB LED,  but just keep in mind that the LED cannot represent the colors that much accurate.

As an example I am using a 3.2” TFT Touch Screen in a combination with a TFT LCD Arduino Mega Shield. We need a shield because the TFT Touch screen works at 3.3V and the Arduino Mega outputs are 5 V. For the first example I have the HC-SR04 ultrasonic sensor, then for the second example an RGB LED with three resistors and a push button for the game example. Also I had to make a custom made pin header like this, by soldering pin headers and bend on of them so I could insert them in between the Arduino Board and the TFT Shield.

Here’s the circuit schematic. We will use the GND pin, the digital pins from 8 to 13, as well as the pin number 14. As the 5V pins are already used by the TFT Screen I will use the pin number 13 as VCC, by setting it right away high in the setup section of code.

I will use the UTFT and URTouch libraries made by Henning Karlsen. Here I would like to say thanks to him for the incredible work he has done. The libraries enable really easy use of the TFT Screens, and they work with many different TFT screens sizes, shields and controllers. You can download these libraries from his website, RinkyDinkElectronics.com and also find a lot of demo examples and detailed documentation of how to use them.

After we include the libraries we need to create UTFT and URTouch objects. The parameters of these objects depends on the model of the TFT Screen and Shield and these details can be also found in the documentation of the libraries.

Next we need to define the fonts that are coming with the libraries and also define some variables needed for the program. In the setup section we need to initiate the screen and the touch, define the pin modes for the connected sensor, the led and the button, and initially call the drawHomeSreen() custom function, which will draw the home screen of the program.

So now I will explain how we can make the home screen of the program. With the setBackColor() function we need to set the background color of the text, black one in our case. Then we need to set the color to white, set the big font and using the print() function, we will print the string “Arduino TFT Tutorial” at the center of the screen and 10 pixels  down the Y – Axis of the screen. Next we will set the color to red and draw the red line below the text. After that we need to set the color back to white, and print the two other strings, “by HowToMechatronics.com” using the small font and “Select Example” using the big font.

drawDistanceSensor(); // It is called only