tft display construction and working quotation

2023-01-03 12:32:11

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.

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

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

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

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.

Brody, T. Peter; Asars, J. A.; Dixon, G. D. (November 1973). "A 6 × 6 inch 20 lines-per-inch liquid-crystal display panel". 20 (11): 995–1001. Bibcode:1973ITED...20..995B. doi:10.1109/T-ED.1973.17780. ISSN 0018-9383.

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.

tft display construction and working quotation

TFT Liquid crystal display products are diversified, convenient and versatile, simple to keep up, upgrade, update, long service life, and have many alternative characteristics.

The display range covers the appliance range of all displays from one to forty inches and, therefore, the giant projection plane could be a large display terminal.

Display quality from the most straightforward monochrome character graphics to high resolution, high colour fidelity, high brightness, high contrast, the high response speed of various specifications of the video display models.

In particular, the emergence of TFT LCD electronic books and periodicals will bring humans into the era of paperless offices and paperless printing, triggering a revolution in the civilized way of human learning, dissemination, and recording.

It can be generally used in the temperature range from -20℃ to +50℃, and the temperature-hardened TFT LCD can operate at low temperatures up to -80 ℃. It can be used as a mobile terminal display or desktop terminal display and can be used as a large screen projection TV, which is a full-size video display terminal with excellent performance.

The manufacturing technology has a high degree of automation and sound characteristics of large-scale industrial production. TFT LCD industry technology is mature, with a more than 90% mass production rate.

It is an ideal combination of large-scale semiconductor integrated circuit technology and light source technology and has good potential for more development.

From the beginning of flat glass plates, its display effect is flat right angles, letting a person have a refreshing feeling. LCDs are simple to achieve high resolution on small screens.

tft display construction and working quotation

Get rich colors, detailed images, and bright graphics from an LCD with a TFT screen. Our standard Displaytech TFT screens start at 1” through 7” in diagonal size and have a variety of display resolutions to select from. Displaytech TFT displays meet the needs for products within industrial, medical, and consumer applications.

TFT displays are LCD modules with thin-film transistor technology. The TFT display technology offers full color RGB showcasing a range of colors and hues. These liquid crystal display panels are available with touchscreen capabilities, wide viewing angles, and bright luminance for high contrast.

Our TFT displays have LVDS, RGB, SPI, and MCU interfaces. All Displaytech TFT LCD modules include an LED backlight, FPC, driver ICs, and the LCD panel.

We offer resistive and capacitive touch screens for our 2.8” and larger TFT modules. Our TFT panels have a wide operating temperature range to suit a variety of environments. All Displaytech LCDs are RoHS compliant.

We also offer semi-customization to our standard TFT screens. This is a cost-optimized solution to make a standard product better suit your application’s needs compared to selecting a fully custom TFT LCD. Customizations can focus on cover glass, mounting / enclosures, and more - contact us to discuss your semi-custom TFT solution.

tft display construction and working quotation

TFT displays have become increasingly common in our daily lives. They are used in cars, laptops, tablets, and smartphones, as well as in industrial applications and many more. But what are TFT displays and why are they so important?

A TFT (Thin Film Transistor) display is a type of display technology that uses a thin layer of transparent material to produce an image on the screen. The display is made up of thin layers of organic material called organic transistors, which are stacked together on a glass substrate and covered with a thin layer of plastic or metal oxide.

TFT displays are also used in many other industrial applications, such as industrial control systems, medical devices, automotive infotainment systems, and more.

The basic concept behind a TFT display is simple: it uses light to create an image on a screen. Light passes through the glass substrate and the organic transistors until it reaches the top layer of the display.

The organic transistors turn on and off in response to the electrical charge of light passing through them. As they do so, they produce voltages that are then sent through wires connected to each pixel of the screen to create an image.

The number of pixels that can be displayed depends on how many organic transistors are used in each pixel or subpixel (a single-pixel is made up of multiple subpixels). For example, a 4-inch (10 cm) display has a pixel pitch of 0.0625 inches (1.57 mm).

The basic design of a TFT display has remained unchanged for more than 20 years. In this design, the sub-pixels are arranged in a grid pattern, with each subpixel connected to its neighbor by wires that form rows and columns.

The number of wires per pixel depends on the size and resolution of the screen: the larger and higher resolution of the screen, the fewer wires need to be used.

In 1982, Sanyo introduced the world’s first 16-inch (40 cm) LCD with a resolution of 640×480 pixels. This was followed by the introduction of 30-inch (76 cm) screens in 1984 and 40-inch (100 cm) screens in 1985.

The first large format TFT display was introduced in 1987 by NEC Corporation, which used a 1024×768 pixel screen for its PC monitor line, called CRT Professional Display System or “Videotronic” system. The technology was licensed to NEC’s competitors such as Hitachi and Toshiba for use in their own monitors and televisions. The system was marketed as “Super Video” and replaced the aging “Videotron” CRT monitors that were still being used at the time. The first LCD TV was also produced in 1987 by Sony.

In 1989, Sharp’s first TFT-LCD TV set was introduced with a resolution of 576×320 pixels, while the world’s first large format high definition screen with a resolution of 1024×768 pixels was introduced by NEC in 1994.

Over the years, TFT display technology has developed by leaps and bounds. It has been used in tablets, smartphones, notebooks, game consoles, and computer monitors. The technology is also used in digital cameras, camcorders, MP3 players, and GPS devices.

What does the TFT display technology comprise? From far, you can easily assume TFT to be a single unit. But in reality, it comprises different components that work together.

The backlight of the TFT display is a very important component. It provides the light for the pixels and is also responsible for illuminating the display. The light emitted by a backlight can be controlled by varying the amount of current running through it.

When it comes to LCD displays, there are two types of backlights; Active matrix and Passive matrix. Active matrix backlight has several layers of electrodes, which are used to control the amount of current flowing through them.

Whereas, Passive matrix backlight consists of one electrode layer that acts as a switch between off and on states. The active matrix backlights are more expensive than passive-matrix ones because they require more power to operate.

The pixel is the smallest unit in a TFT display. It is the basic unit of information that is displayed on the screen. The pixel consists of three sub-elements, namely; Red, Green, and Blue (RGB).

The number of sub-pixels that are used in each pixel varies with different display technologies. In full-color LCDs, there are three types of sub-pixel: red, green, and blue (RGB). Full color TFT displays use a combination of Red, Green, and Blue (RGB) sub-pixels to represent full color.

The backplane and frontplane are connected by a number of flexible printed circuits. The PCBs are usually connected to each other with wires made from metals such as copper or aluminum. These wires are used to supply power, data, and control signals between the backplane and the front-plane.

The light that is transmitted through each TFT is controlled by applying voltages of different values to each pixel in turn. To do this, a control circuit called a driver circuit is required. The driver circuit controls the voltage applied to each pixel with reference to a set of parameters known as “pixel information”.

This information includes color, brightness, and other characteristics that define how an individual pixel should be operated for display purposes. The parameters also include how many red, green and blue sub-pixels are used to produce each pixel.

The control system can be further divided into 3 sub-systems: the interface, the timing, and the data transfer system (DTS). These systems work together to provide all of the necessary functions for controlling TFT displays from external sources such as computers, printers, or TVs.

This is another component of a TFT display system. It consists of a liquid crystal material sandwiched between two glass plates. This material is responsible for controlling the light by changing its refractive index.

-Wide viewing angle: The viewing angle of the TFT display is larger than that of the CRT set. It is generally considered to be the best choice for applications requiring an extended viewing angle.

-Transparency: TFT display has better transparency than CRT set, which makes it more suitable for applications requiring high transparency such as window displays and computer monitors.

-High resolution: TFT display can produce higher resolution than CRT display. For example, the pixel density of TFT is about 3 million pixels per square inch (PPI), which is about three times that of conventional liquid crystal displays (LCDs) whose pixel density is about 100 ppi.

-Reliability: Since it uses no moving parts, the TFT screen does not need any maintenance or repair, and therefore the reliability is higher than that of LCDs and plasma displays.

-Power saving: TFT display consumes much less power than CRT. The power consumption of a mainstream TFT display is about 1/10 that of a typical LCD. In some applications, the power consumption can be reduced to 1/100 or less of that of a CRT.

-High brightness: The picture displayed on the screen can be bright enough to be seen in bright sunlight without any need for glare reduction filters.

-Compatibility: Since it uses no moving parts, the TFT screen does not have any mechanical problems such as screen flicker and image sticking problems found in plasma displays and LCDs.

-High resolution: Although the pixel density of TFT is about 3 million pixels per square inch (ppi), the resolution is more than 100 ppi which makes it more suitable for many applications where high resolution is needed.

-Consistency: Since it uses no moving parts, the image displayed on the TFT display is not affected by temperature and humidity, which makes it more consistent than LCDs and plasma displays.

-Cost: The cost of a TFT display is lower than that of LCDs and plasma displays. For example, in some applications where image quality is not critical, the cost of a TFT display may be only a few tens to a few hundreds of dollars while the cost of LCDs or plasma displays may be several thousand to several tens of thousands.

-Excellent color display: We can’t deny the fact that TFTs have a superior color display. This simply means that the color of pixels can be accurately reproduced.

-Very thin: When compared with LCDs and plasma displays, which are very thick, TFTs are very thin and lightweight. In addition, the cost of mounting a large size TFT screen to a wall panel is relatively low.

-No ghosting: ‘Ghosting’ refers to the fact that the display shows a bright spot on the screen when the screen is turned off. TFT screens do not show ghosting. TFTs produce a sharp image even when they are turned off.

-No geometric distortion: Geometric distortion refers to the shape of the display on a flat surface. TFTs produce a sharp image even when they are turned off.

-No radiation: TFTs do not emit any harmful radiation, and there is no need for shielding or shielding materials to protect people from harmful radiation.

Considering that TFTs use less power, it is possible to reduce energy consumption by up to 50% compared with LCDs. In addition, if you use LED backlights in TFT displays, you can reduce power consumption by up to 75% compared with conventional backlights.

The screen quality of a product can be improved by reducing scratches on the screen surface caused by friction between the screen surface and fingers or objects that come into contact with it during daily use (e.g., keys). In addition, the life cycle of a product can be increased by reducing the possibility of product damage due to scratches on the screen surface.

If a product uses a backlight, there is a high possibility that the color of the screen will be affected after some time due to dust or dirt that comes into contact with it. But it is possible to prevent this problem by using TFTs with LED backlights, which have no problems such as those caused by dust and dirt.

It is possible to reduce power consumption and extend product life by reducing backlight power consumption and extending product life. In addition, if you use LEDs for backlights, you can reduce power consumption by up to 75% compared with conventional backlights.

Workability refers to the ease with which you can operate a product. When working with a screen that has TFTs, it is possible to increase the amount of information that can be displayed at one time. It is also possible to reduce the number of times you must change settings on a product by increasing its usability.

Design refers to what you can create with the use of a product. Using TFTs, it is possible to create products that have a thin profile and are lightweight, which makes them more convenient for transportation and storage.

Human interface refers to what you touch when using a product or what you see on the screen when using a product (e.g., buttons and other controls). By integrating the TFTs into the display part of a product, it is possible to make the human interface easier.

Amoled refers to a technology that replaces the traditional liquid crystal display (LCD) with an organic light-emitting diode (OLED). Modern TFTs are similar to Amoled in terms of their structure, but they differ from Amoled in terms of their performance.

The TFTs of the present invention have superior characteristics compared to Amoled, such as high contrast ratio and response speed. The TFTs also have superior characteristics compared to conventional display devices such as CRT and plasma display panels, which cannot be achieved by these conventional display devices.

IPS refers to a technology that replaces the traditional liquid crystal display (LCD) with in-plane switching technology. The IPS display has superior features to TFT due to its high contrast ratio, wide viewing angle, and high response speed.

There are certain limitations to TFTs. For example, there is a limit to the size of the display and the resolution of the image that can be displayed on a display. Also, because TFTs are considered to be a kind of organic semiconductor displays, they have a short life span and therefore need frequent replacement.

Because of their high resolution, TFT displays are used in display monitors. The type of TFT used in display monitors can be categorized as either active matrix or passive matrix. Active matrix TFTs use a thin film transistor (TFT) as its active component, whereas passive matrix uses a liquid crystal display (LCD).

TFTs are also being used in portable electronic devices such as mobile phones, personal digital assistants (PDAs), and cameras. These devices require high-resolution screens because the user must be able to view accurate images and text on the screen. TFTs are also being used in laptops, which have a much larger screen size than many other portable electronic devices.

Because of their size and high resolution, laptop computers use passive matrix TFT displays instead of LCDs for larger displays than those found on smaller-sized portable electronics devices that use LCDs for their displays (e.g., mobile phones and PDAs).

TFT displays are used in front-projection TVs. The type of TFT used in front-projection TVs can be categorized as either active matrix or passive matrix. Active matrix TFTs use a thin film transistor (TFT) as its active component, whereas passive matrix uses a liquid crystal display (LCD).

Head-mounted displays (HMDs) use liquid crystal on silicon technology to create small, inexpensive, low-power VR headsets that can be worn on the head. Some HMDs use active matrix TFT technology while others use passive matrix TFT technology. Active matrix HMDs use shorting bars or glass electrodes to control each pixel; passive matrix HMDs use a liquid crystal material that allows for the creation of an image by controlling the voltage applied to each pixel.

TFTs are used in projectors to create the on-screen image from the input signal. TFTs are used in both active matrix and passive matrix projectors. Active matrix projectors use shorting bars or glass electrodes to control each pixel, while passive matrix projectors use a liquid crystal material that allows for the creation of an image by controlling the voltage applied to each pixel.

CCDs are used in digital cameras and DV camcorders to capture still images and video, respectively. CCDs use a single array of photosites that each receives an electrical charge during exposure to light, resulting in an electrical signal that is output as an image. TFTs are used in CCDs as display circuits for previewing pictures.

TFTs are used in the display of gaming systems such as consoles, personal computers, and hand-held devices. TFTs are also used in the display of mobile telephones and in digital signs.

There are many factors to consider when buying a TFT display. The most important factors are the size of the display, the resolution of the display, and whether or not it is touch-sensitive.

It is also vital to consider where you are buying your TFT display system. A good place to buy a TFT display is from an authorized dealer or an online store. You should also consider whether or not the TFT display system you are looking for has a warranty.

At ICRFQ, we can connect you to the best TFT display suppliers and manufacturers in China. Just contact us and we will do what a reliable sourcing agent should do!

tft display construction and working quotation

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.

For this tutorial I composed three examples. The first example is distance measurement using ultrasonic sensor. The output from the sensor, or the distance is printed on the screen and using the touch screen we can select the units, either centimeters or inches.

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.

As the code is a bit longer and for better understanding I will post the source code of the program in sections with description for each section. And at the end of this article I will post the complete source 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.

Next is the distance sensor button. First we need to set the color and then using the fillRoundRect() function we will draw the rounded rectangle. Then we will set the color back to white and using the drawRoundRect() function we will draw another rounded rectangle on top of the previous one, but this one will be without a fill so the overall appearance of the button looks like it has a frame. On top of the button we will print the text using the big font and the same background color as the fill of the button. The same procedure goes for the two other buttons.

Now we need to make the buttons functional so that when we press them they would send us to the appropriate example. In the setup section we set the character ‘0’ to the currentPage variable, which will indicate that we are at the home screen. So if that’s true, and if we press on the screen this if statement would become true and using these lines here we will get the X and Y coordinates where the screen has been pressed. If that’s the area that covers the first button we will call the drawDistanceSensor() custom function which will activate the distance sensor example. Also we will set the character ‘1’ to the variable currentPage which will indicate that we are at the first example. The drawFrame() custom function is used for highlighting the button when it’s pressed. The same procedure goes for the two other buttons.

getDistance(); // Gets distance from the sensor and this function is repeatedly called while we are at the first example in order to print the lasest results from the distance sensor

Here’s that function which uses the ultrasonic sensor to calculate the distance and print the values with SevenSegNum font in green color, either in centimeters or inches. If you need more details how the ultrasonic sensor works you can check my particular tutorialfor that. Back in the loop section we can see what happens when we press the select unit buttons as well as the back button.

Ok next is the RGB LED Control example. If we press the second button, the drawLedControl() custom function will be called only once for drawing the graphic of that example and the setLedColor() custom function will be repeatedly called. In this function we use the touch screen to set the values of the 3 sliders from 0 to 255. With the if statements we confine the area of each slider and get the X value of the slider. So the values of the X coordinate of each slider are from 38 to 310 pixels and we need to map these values into values from 0 to 255 which will be used as a PWM signal for lighting up the LED. If you need more details how the RGB LED works you can check my particular tutorialfor that. The rest of the code in this custom function is for drawing the sliders. Back in the loop section we only have the back button which also turns off the LED when pressed.

In order the code to work and compile you will have to include an addition “.c” file in the same directory with the Arduino sketch. This file is for the third game example and it’s a bitmap of the bird. For more details how this part of the code work you can check my particular tutorial. Here you can download that file:

getDistance(); // Gets distance from the sensor and this function is repeatedly called while we are at the first example in order to print the lasest results from the distance sensor

tft display construction and working quotation

While in theory an Arduino can run any LCD, we believe that some LCDs are particularly suited to being an Arduino LCD display. We"ve currated this list of LCD displays that will make any Arduino-based project shine.

First is the interface. All of these displays support SPI. Builders often ask themselves (or us) "which interface uses the fewest GPIO pins? AND is that interface fast enough to update the screen at an acceptable rate for my application?" When using the relatively small procesor of the Arduino, SPI is usually the best interface because it takes few wires (either 3 or 4) however it does limit the overall size (number of pixels) that can be quickly controlled. I2C is another choice of interface to leave GPIOs open. We tend to recommend SPI over I2C for Arduino displays because SPI is quicker and better at handling more complex data transfer, like pulling image data from an SD card.

Which brings us to the second factor in choosing an Arduino display: the number of pixels. We typically recommend a display with a resolution of 320x240 or less for use with Arduino. Take for example a 320x240 24-bit display. Such a display takes 230,400 bytes *(8 + 2) = 2,304,000 bits for a single frame. Divide that by 8,000,000 (Arduino SPI speed of 8MHZ) = 0.288 seconds per frame or 3.5 frames per second. 3.5 fps is fast enough for many applications, but is not particularly quick. Using fewer bits-per-pixel or a display with fewer pixels will result in higher frame rates. Use the calculator below to calculate the frame rate for a display using SPI with an Arduino.

Third, we want to recommend displays that are easy to connect to an Arduino. Each of these displays has a ZIF tail or easily solderable throughholes, so no fine pitch soldering is needed. These displays can either be brought up on the CFA10102 generic breakout board, or with a custom CFA breakout board.

Most character displays can be run via Parallel connection to an Arduino. You"ll want to make sure you can supply enough current to operate the backlight.

tft display construction and working quotation

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

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

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

On the surface level is the other glass substrate. Just beneath this glass substrate is where the actual pixels and sub-pixels reside, forming the RGB color filter. In order to counteract the electrodes of the previously mentioned layer, this surface layer has counter (or common) electrodes on the side closer to the liquid crystals that close off the circuit that travels between the two layers. In both these substrate layers, the electrodes are most frequently made of indium tin oxide (ITO) because they allow for transparency and have good conductive properties.

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

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

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

Fig. 2: On the left is the twisted liquid crystal layer in which polarized light passes freely; on the right is after the electric field is charged into the layer, completely re-aligning the molecule orientations so that light is not polarized and cannot pass through the surface polarizer.

The twisted nematic effect is one of the cheapest options for LCD technology, and it also allows for fast pixel response time. There are still some limits, though; color reproduction quality may not be great, and viewing angles, or the direction at which the screen is looked at, are more limited.

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

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

Within an LCD, each pixel can be characterized by its three sub-pixels. These three sub-pixels create the RGB colorization of that overall pixel. These sub-pixels act as capacitors, or electrical storage units within a device, each with their own independent structural and functional layers as described earlier. With the three sub-pixels per pixel, colors of almost any kind can be mixed from the light passing through the filters and polarizer at different brightness based on the liquid crystal alignment.

tft display construction and working quotation

Liquid Crystal Pixels are transmission type pixels with a backlight, meaning that they are not emitting their own light. While there are many types of liquid crystal materials such as smectics, nematics and cholesterics, twisted nematic (TN) display mode is the most advanced and popular. A TN pixel cell consists of two glass substrates coated on their inner surfaces with transparent electrodes and separated by several millimeters from each other. A nematic liquid crystal material fills the space between the two substrates and two polarizers are attached on both sides of the pixel with their polarization axis crossed. The polarizer is a three-layer composite film with a stretched iodine doped polyvinyl alcohol (PVA) polarizing film in the center and two outer films for protecting the PVA film from the ambient. Since the two substrates, each having alignment layer, are oriented with their alignments perpendicular to each other, liquid molecule is twisted initially. In the voltage-off state, the polarizers are oriented perpendicular and the incoming light from a back light source, whose polarity is twisted by the liquid crystal, is transmitted through the output polarizer. When a voltage is applied to the electrodes, the director of the molecules tends to orient themselves parallel to the applied field, since liquid crystal materials have positive dielectric anisotropy. In this situation, the polarization of the light transmitted through liquid crystal is crossed to the output polarizer resulting in the cut off of the light and thus creating a black state for the display pixel. This operation is called normally white mode, while normally black mode can be achieved by changing the polarizers to a parallel orientation. Figure 10 shows the configuration a TN pixel cell in a normally white mode.

The transmission (luminance) versus the applied voltage characteristic is shown in Fig. 11. The shown characteristic is for normal viewing angle and indicates that grayscale levels can be achieved by varying the voltage across the LCD. Unfortunately, the transmission – voltage curve is viewing angle dependent, leading to grayscale errors and color shift in a display when it is viewed from significant angles to the display normal.

The equivalent circuit with the parasitic elements of a pixel cell and a typical TFT-LCD pixel layout are shown in fig. 12. The pixel consists of a switch TFT device, with the gate electrode connected to the row driver lines and the source electrode connected to the column driver lines. Furthermore, a storage capacitor is connected in parallel to the LC pixel capacitance.

The aperture part is the light transparent part and it is designated for the placement of the liquid crystal while the TFT, voltage lines and storage capacitor areas are non-light transparent. The ratio between the transparent portion of a pixel and its surrounding electronics is called aperture ratio or fill factor. Furthermore, in the shown layout design, the storage capacitor is connected to an adjacent row line resulting in the maximization of the aperture ration but the load capacitance of the row lines is, also, increased. The counter electrode of the LC pixel capacitor is the common ITO electrode on the opposite substrate (Den Boer, 2005). For large displays, this configuration is difficult to be used due to the large RC delay time of the row lines. In order to overcome this problem, a common storage bus can be placed in the aperture area which reduces the load capacitance of the row lines, but also reduces the aperture ration of the pixel.

The crosstalk effect is caused due to the column-line video-signal coupling during one frame and a DC component is being added to the AC data voltage. The DC component can not be entirely eliminated for all gray across the entire pixels matrix, resulting to slight difference in the pixel transmittance between the odd and even frames. A solution to this problem is the polarity inversion method. Apart from elimination of the DC component, the influence of the flicker on the display image quality is also eliminated with the use of a polarity inversion method. Four different polarity inversion methods have been widely used. Figure 13 shows the configuration of the four polarity inversion methods. The type of the polarity inversion method has an impact on the power consumption of the display. In the frame inversion method, all the pixels are driven to + Vp polarity in one frame period and then all of them are driven to – Vp polarity during the next frame period. This method is the most power-efficient method. However, this method is sensitive to the flicker and to vertical and horizontal crosstalk, meaning that this method can not be used in high image quality displays.

In the line and column inversion methods, the polarity of the pixels is alternated in the adjacent rows and columns, respectively. The line inversion method is compatible to the Vcom modulation (Den Boer, 2005) while column inversion method is not compatible. Furthermore, the line inversion method consumes more power than the column inversion method because the capacitance of all row busses is charged and discharged every row time. Finally, the column inversion method has better results to the compensation of the flicker.

In the pixel inversion method, the polarity of each pixel is inverted from the polarity of its neighbouring pixels, by a combination of simultaneous row and column inversions. This produces the highest quality images by total elimination of the flicker and crosstalk effect. This method is not compatible with the Vcom modulation and thus it requires high voltage column drivers leading to high power consumption.

A full color LCD display can be generated by incorporating red, green and blue color filters at the pixels. In order to produce the desirable color tone, the pixel is divided into three sub-pixels each one having red, green and blue color filter, respectively. The three sub-pixels have the same dimensions and the proper combination of each color tone; by applying the right voltages to the liquid crystals, the desired pixel emissive colour will be produced. The width of each sub-pixel is three times smaller than the sub-pixel length and when the three sub-pixels are very closely placed in parallel, a square full color pixel is produced. Figure 14 shows a full colour square pixel.

tft display construction and working quotation