tft lcd principle in stock

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.

The outer sides of the glass substrates (closest to the surface or closest to the back) have filter layers called polarizers. These filters allow only certain beams of light to pass through if they are polarized in a specific manner, meaning that the geometric waves of the light are appropriate for the filter. If not polarized correctly, the light does not pass through the polarizer which creates an opaque LCD screen.

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.

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.

LCD (Liquid Crystal Display)may be a fresh noun for many users, but the history of this technology may far exceed our imagination. As early as the end of the 19th century, Austrian botanists discovered liquid crystals, that is, a substance has both the fluidity of liquids and certain crystal-like arrangement characteristics.

This phenomenon is called the electro-optic effect. Utilizing the electro-optical effect of liquid crystals, British scientists produced the first liquid crystal display, the LCD display, in the last century.

According to the driving method of the LCD panel, the most common currently is a TFT (Thin Film Transistor) type driver. It achieves independent and precise control of each pixel through the active switch, so it can achieve more fine display effects than the previous passive driver (commonly known as pseudo color). Therefore, most LCD displays,LCD displayTVs and some mobile phones are driven by TFT.

Therefore, as long as we change the voltage value applied to the liquid crystal, we can control the intensity and color of the light that finally appears, so that we can change the color combination with the different hue on theLCD display panel.

TFT-LCD was invented in 1960 and successfully commercialized as a notebook computer panel in 1991 after continuous improvement, thus entering the TFT-LCD generation.

Simply put, the basic structure of the TFT-LCD panel is a layer of liquid crystal sandwiched between two glass substrates. The front TFT display panel is coated with a color filter, and the back TFT display panel is coated with a thin film transistor (TFT). When a voltage is applied to the transistor, the liquid crystal turns and light passes through the liquid crystal to create a pixel on the front panel. The backlight module is responsible for providing the light source after the TFT-Array panel. Color filters give each pigment a specific color. The combination of each different color pixel gives you an image of the front of the panel.

The TFT panel is composed of millions of TFT devices and ITO (In TI Oxide, a transparent conductive metal) regions arranged like a matrix, and the so-called Array refers to the region of millions of TFT devices arranged neatly, which is the panel display area. The figure below shows the structure of a TFT pixel.

No matter how the design of TFT display board changes or how the manufacturing process is simplified, its structure must have a TFT device and control liquid crystal region (if the light source is penetration-type LCD, the control liquid crystal region is ITO; but for reflective LCD, the metal with high reflection rate is used, such as Al).

The TFT device is a switch, whose function is to control the number of electrons flowing into the ITO region. When the number of electrons flowing into the ITO region reaches the desired value, the TFT device is turned off. At this time, the entire electrons are kept in the ITO region.

The figure above shows the time changes specified at each pixel point. G1 is continuously selected to be turned on by the driver IC from T1 to TN so that the source-driven IC charges TFT pixels on G1 in the order of D1, D2, and Dn. When TN +1, gATE-driven IC is selected G2 again, and source-driven IC is selected sequentially from D1.

Many people don’t understand the differences between generations of TFT-LCD plants, but the principle is quite simple. The main difference between generations of plants is in the size of glass substrates, which are products cut from large glass substrates. Newer plants have larger glass substrates that can be cut to increase productivity and reduce costs, or to produce larger panels (such as TFT display LCD TV panels).

The TFT-LCD industry first emerged in Japan in the 1990s, when a process was designed and built in the country. The first-generation glass substrate is about 30 X 40 cm in size, about the size of a full-size magazine, and can be made into a 15-inch panel. By the time Acer Technology (which was later merged with Unioptronics to become AU Optronics) entered the industry in 1996, the technology had advanced to A 3.5 generation plant (G3.5) with glass substrate size of about 60 X 72 cm.Au Optronics has evolved to a sixth-generation factory (G6) process where the G6 glass substrate measures 150 X 185 cm, the size of a double bed. One G6 glass substrate can cut 30 15-inch panels, compared with the G3.5 which can cut 4 panels and G1 which can only cut one 15-inch panel, the production capacity of the sixth generation factory is enlarged, and the relative cost is reduced. In addition, the large size of the G6 glass substrate can be cut into large-sized panels, which can produce eight 32-inch LCD TV panels, increasing the diversity of panel applications. Therefore, the global TFT LCD manufacturers are all invested in the new generation of plant manufacturing technology.

The TRANSISTor-LCD is an acronym for thin-film TFT Display. Simply put, TFT-LCD panels can be seen as two glass substrates sandwiched between a layer of liquid crystal. The upper glass substrate is connected to a Color Filter, while the lower glass has transistors embedded in it. When the electric field changes through the transistor, the liquid crystal molecules deflect, so as to change the polarization of the light, and the polarizing film is used to determine the light and shade state of the Pixel. In addition, the upper glass is fitted to the color filter, so that each Pixel contains three colors of red, blue and green, which make up the image on the panel.

The luminescence principle is tied to the vapor electroplating organic film between the transparent anode and the metal cathode. The electron and electric hole are injected, and the energy is converted into visible light by the composite between the organic film. And can match different organic materials, emit different colors of light, to achieve the requirements of the full-color display.

The organic light display can be divided into Passive Matrix (PMOLED) and Active Matrix (AMOLED) according to the driving mode. The so-called active driven OLED(AMOLED) can be visualized in the Thin Film Transistor (TFT) as a capacitor that stores signals to provide the ability to visualize the light in a grayscale.

Although the production cost and technical barriers of passive OLED are low, it is limited by the driving mode and the resolution cannot be improved. Therefore, the application product size is limited to about 5″, and the product will be limited to the market of low resolution and small size. For high precision and large picture, the active drive is mainly used. The so-called active drive is capacitive to store the signal, so when the scanning line is swept, the pixel can still maintain its original brightness. In the case of passive drive, only the pixels selected by the scan line are lit. Therefore, in an active-drive mode, OLED does not need to be driven to very high brightness, thus achieving better life performance and high resolution.OLED combined with TFT technology can realize active driving OLED, which can meet the current display market for the smoothness of screen playback, as well as higher and higher resolution requirements, fully display the above superior characteristics of OLED.

The technology to grow The TFT on the glass substrate can be amorphous Silicon (A-SI) manufacturing process and Low-Temperature Poly-Silicon (LTPS). The biggest difference between LTPS TFT and A-SI TFT is the difference between its electrical properties and the complicated manufacturing process. LTPS TFT has a higher carrier mobility rate, which means that TFT can provide more current, but its process is complicated.A-si TFT, on the other hand, although a-Si’s carrier movement rate is not as good as LTPS’s, it has a better competitive advantage in cost due to its simple and mature process.Au Optronics is the only company in the world that has successfully combined OLED with LTPS and A-SI TFT at the same time, making it a leader in active OLED technology.

The LTPS membrane is much more complex than a-SI, yet the LTPS TFT is 100 times more mobile than A-SI TFT. And CMOS program can be carried out directly on a glass substrate. Here are some of the features that p-SI has over A-SI:

LCD screens are backlit to project images through color filters before they are reflected in our eye Windows. This mode of carrying backlit LCD screens, known as “penetrating” LCD screens, consumes most of the power through backlit devices. The brighter the backlight, the brighter it will appear in front of the screen, but the more power it will consume.

A liquid crystal display (LCD) has liquid crystal material sandwiched between two sheets of glass. Without any voltage applied between transparent electrodes, liquid crystal molecules are aligned in parallel with the glass surface. When voltage is applied, they change their direction and they turn vertical to the glass surface. They vary in optical characteristics, depending on their orientation. Therefore, the quantity of light transmission can be controlled by combining the motion of liquid crystal molecules and the direction of polarization of two polarizing plates attached to the both outer sides of the glass sheets. LCDs utilize these characteristics to display images.

An LCD consists of many pixels. A pixel consists of three sub-pixels (Red/Green/Blue, RGB). In the case of Full-HD resolution, which is widely used for smartphones, there are more than six million (1,080 x 1,920 x 3 = 6,220,800) sub-pixels. To activate these millions of sub-pixels a TFT is required in each sub-pixel. TFT is an abbreviation for "Thin Film Transistor". A TFT is a kind of semiconductor device. It serves as a control valve to provide an appropriate voltage onto liquid crystals for individual sub-pixels. A TFT LCD has a liquid crystal layer between a glass substrate formed with TFTs and transparent pixel electrodes and another glass substrate with a color filter (RGB) and transparent counter electrodes. In addition, polarizers are placed on the outer side of each glass substrate and a backlight source on the back side. A change in voltage applied to liquid crystals changes the transmittance of the panel including the two polarizing plates, and thus changes the quantity of light that passes from the backlight to the front surface of the display. This principle allows the TFT LCD to produce full-color images.

The liquid crystal cannot emit light by itself, and the backlight should be added behind the LCD panel. A few years ago, CCFL cold cathode backlighting was the dominant market application, but with the development of technology, the LED backlight has gradually replaced the traditional CCFL backlight.

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 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.

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.

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.

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.

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.

Scan line: scan line, control TFT switch. The transistors on the control TFT are on/off. When On, data can be transmitted; when off, data can not be transmitted.

Color filter is the key element in the color of liquid crystal display. Through the color filter, the high gray scale liquid crystal display can be fully coloured. So the function of the color filter is to produce RGB Triple Light in the way of filter light, and then mix the three original light with different strong and weak proportions to show all kinds of colors, so that the LCD displays the full color.

The backlight module is mainly used to provide the light source with uniform and high brightness of the liquid crystal panel. Because of the non self luminescence of TFT-LCD, the external light source, such as the light emitting diode and the cold cathode ray tube, must be used.

Therefore, in the design of TFT LCD, to improve the opening rate as much as possible, because only to increase the opening rate, you can increase the brightness, and the brightness of the backlight plate is not so high, can save electricity consumption and cost.

The action of the TFT element is similar to a switch (Switch), and the role of the liquid crystal element is similar to that of a capacitor, i.e., the Switch of the ON/OFF updates / holds the stored voltage values of the capacitor.

The following figure is an equivalent circuit of TFT pixels. The Gate Line connects all the TFT gate electrodes on the same column, while the Source Line connects all the TFT source electrodes on the same line.

When ON, the data of the Source Line is written to the liquid crystal capacitor. At this point, the TFT element is low impedance (RON), and when the OFF is Line, the TFT element is high impedance (ROFF), which prevents leakage of the Source data.

The signals coming in from the Interface Connector include power VDD, data signals, and control signals. The VDD goes into DCDC Converter and becomes a 3.3V digital supply voltage DVDD, which needs to be powered by SOURCE, IC, GATE, IC, and T/CON. The other is analog supply voltage AVDD. It supplies power to the Gamma section, the Source IC. From DCDC, there are TFT open voltage Von and turn off voltage Voff. Data signals and control signals are entered into the T/CON, which generates control timing and is transmitted to the Source, IC, and gate IC along with the data. The Gamma circuit is used to generate the Gamma reference voltage, which is sent to the source IC, and the voltage values corresponding to each gray level are changed by the DA converter in the Source IC. The Vcom (CF reference voltage) is generated by the VCOM circuit and is typically introduced from the PCB board to the panel via Source, IC, and Gate IC

In this article, you will learn how to use TFT LCDs by Arduino boards. From basic commands to professional designs and technics are all explained here.

There are several components to achieve this. LEDs,  7-segments, Character and Graphic displays, and full-color TFT LCDs. The right component for your projects depends on the amount of data to be displayed, type of user interaction, and processor capacity.

TFT LCD is a variant of a liquid-crystal display (LCD) that uses thin-film-transistor (TFT) technology to improve image qualities such as addressability and contrast. A TFT LCD is an active matrix LCD, in contrast to passive matrix LCDs or simple, direct-driven LCDs with a few segments.

In Arduino-based projects, the processor frequency is low. So it is not possible to display complex, high definition images and high-speed motions. Therefore, full-color TFT LCDs can only be used to display simple data and commands.

There are several components to achieve this. LEDs,  7-segments, Character and Graphic displays, and full-color TFT LCDs. The right component for your projects depends on the amount of data to be displayed, type of user interaction, and processor capacity.

TFT LCD is a variant of a liquid-crystal display (LCD) that uses thin-film-transistor (TFT) technology to improve image qualities such as addressability and contrast. A TFT LCD is an active matrix LCD, in contrast to passive matrix LCDs or simple, direct-driven LCDs with a few segments.

In Arduino-based projects, the processor frequency is low. So it is not possible to display complex, high definition images and high-speed motions. Therefore, full-color TFT LCDs can only be used to display simple data and commands.

In electronics/computer hardware a display driver is usually a semiconductor integrated circuit (but may alternatively comprise a state machine made of discrete logic and other components) which provides an interface function between a microprocessor, microcontroller, ASIC or general-purpose peripheral interface and a particular type of display device, e.g. LCD, LED, OLED, ePaper, CRT, Vacuum fluorescent or Nixie.

The LCDs manufacturers use different drivers in their products. Some of them are more popular and some of them are very unknown. To run your display easily, you should use Arduino LCDs libraries and add them to your code. Otherwise running the display may be very difficult. There are many free libraries you can find on the internet but the important point about the libraries is their compatibility with the LCD’s driver. The driver of your LCD must be known by your library. In this article, we use the Adafruit GFX library and MCUFRIEND KBV library and example codes. You can download them from the following links.

Upload your image and download the converted file that the UTFT libraries can process. Now copy the hex code to Arduino IDE. x and y are locations of the image. sx and sy are size of the image.

while (a < b) { Serial.println(a); j = 80 * (sin(PI * a / 2000)); i = 80 * (cos(PI * a / 2000)); j2 = 50 * (sin(PI * a / 2000)); i2 = 50 * (cos(PI * a / 2000)); tft.drawLine(i2 + 235, j2 + 169, i + 235, j + 169, tft.color565(0, 255, 255)); tft.fillRect(200, 153, 75, 33, 0x0000); tft.setTextSize(3); tft.setTextColor(0xffff); if ((a/20)>99)

while (b < a) { j = 80 * (sin(PI * a / 2000)); i = 80 * (cos(PI * a / 2000)); j2 = 50 * (sin(PI * a / 2000)); i2 = 50 * (cos(PI * a / 2000)); tft.drawLine(i2 + 235, j2 + 169, i + 235, j + 169, tft.color565(0, 0, 0)); tft.fillRect(200, 153, 75, 33, 0x0000); tft.setTextSize(3); tft.setTextColor(0xffff); if ((a/20)>99)

LCD displays. Of course, there is only one color for the backlight and one color for the characters, but as you can see here on the picture above, there could be many colors of backlights. We can have a white backlight, orange, green, blue or any backlight color.

The last part of this article covers graphic displays and character displays, the difference between them and how it influences the cost of an LCD display. The most basic LCD displays are the segmented monochrome LCD displays or icon displays. In this kind of LCD displays we have only some icons and characters, but they are defined when the display is being produced. What we see on the display is defined and we cannot have anything else, the other area is completely off. You can only switch on and off the display segments. This is the cheapest technology to produce, and it is made by mask during the production, so it is usually reserved for high volume applications, that are very well defined during the production phase. For example, this can a be kind of watch, or calculator, or temperature controller. The advantage is the cost, but the disadvantage is that later we cannot change anything, we cannot change the software and add another icon.

Next, we have the fully graphic display. In this kind of LCD display we have a matrix of pixels. It could be 64 by 256, or 64 by 128 pixels, so on this kind of screen we can show almost every image, because we can switch every pixel on and off. We can show letters, characters, images, small, big, anything we want. The disadvantage is the vast number of pixels that we need to connect. The controller and the glass are complicated, because we need to route the wires from every pixel out from the glass and connect it to the controller. So, in the monochrome LCD display family, this kind of display is the most expensive. Other kinds of displays are cheaper, not only because the glass is simple, but because the controllers are simple too.

As is usually the case with abbreviations used to denote specifics and technical characteristics, there is confusion and substitution of concepts regarding TFT and IPS. Largely due to unqualified descriptions of electronic devices in catalogs, consumers raise the question of choice initially incorrectly. So, the IPS matrix is ​​​​a kind of TFT matrices, so it is impossible to compare these two categories with each other. However, for the Russian consumer, the abbreviation TFT often means TN-TFT technology, and in this case it is already possible to make a choice. So, speaking about the differences between TFT and IPS screens, we will mean TFT screens made using TN and IPS technologies.

TN-TFT- technology for the execution of a matrix of a liquid crystal (on thin-film transistors) screen, when the crystals, in the absence of voltage, rotate to each other at an angle of 90 degrees in a horizontal plane between two plates. The crystals are arranged in a spiral, and as a result, when the maximum voltage is applied, the crystals turn in such a way that when light passes through them, black pixels are formed. No tension - white.

In practice, the most important difference between an IPS matrix and a TN-TFT matrix is ​​the increased level of contrast due to the almost perfect black display. The picture is clearer.

The color rendering quality of TN-TFT matrices leaves much to be desired. Each pixel in this case can have its own hue, different from the others, resulting in distorted colors. IPS already treats the image much more carefully.

The response speed of TN-TFT is slightly higher than that of other matrices. IPS takes time to rotate the entire array of parallel crystals. Thus, when performing tasks where drawing speed is important, it is much more profitable to use TN matrices. On the other hand, in everyday use, a person does not notice the difference in response time.

Monitors and displays based on IPS matrices are much more energy intensive. This is due to the high level of voltage required to rotate the array of crystals. Therefore, TN-TFT technology is more suitable for energy saving tasks in mobile and portable devices.

Another difference that is important for the end user is the price. TN-TFT is by far the cheapest and most mass-produced matrix option, so it is used in budget electronics models.

The technology of LCD TFT matrices provides for the use of special thin-film transistors in the production of liquid crystal displays. The name TFT itself is an abbreviation for Thin-film transistor, which in translation means thin-film transistor. This type of matrix is ​​used in a wide variety of devices, from calculators to smartphone displays.

Probably, everyone has heard the concepts of TFT and LCD, but few people have thought about what it is, which is why unenlightened people have a question, how does TFT differ from LCD? The answer to this question is that they are two different things that should not be compared. To understand the difference between these technologies, it is worth understanding what is LCD and what is TFT.

LCD is a technology for manufacturing TV screens, monitors and other devices based on the use of special molecules called liquid crystals. These molecules have unique properties, they are constantly in a liquid state and are able to change their position when exposed to an electromagnetic field. In addition, these molecules have optical properties similar to those of crystals, which is why these molecules got their name.

As already mentioned, TFT is a technology for manufacturing LCD displays, which involves the use of thin film transistors. Thus, we can say that TFT is a subspecies of LCD monitors. It should be noted that all modern LCD TVs, monitors and phone screens are of the TFT type. Therefore, the question of what is better than TFT or LCD is not entirely correct. After all, the difference between FTF and LCD is that LCD is a technology for manufacturing liquid crystal screens, and TFT is a subspecies of LCD displays, which includes all types of active matrices.

Among TFT users, matrices have a name - active. Such matrices have a significantly higher performance, in contrast to passive LCD matrices. In addition, the LCD TFT screen type is different increased level clarity, image contrast and large viewing angles. Another important point is that there is no flicker in active matrices, which means that it is more pleasant to work behind such monitors, while the eyes are less tired.

Each pixel of the TFT matrix is ​​equipped with three separate driving transistors, which achieves a significantly higher screen refresh rate compared to passive matrices. Thus, each pixel contains three colored cells, which are controlled by the corresponding transistor. For example, if the screen resolution is 1920x1080 pixels, then the number of transistors in such a monitor will be 5760x3240. The use of such a number of transistors became possible due to the ultra-thin and transparent structure - 0.1-0.01 microns.

All well-known LCD TVs available on the Russian market are equipped with TFT displays. They may differ in their parameters depending on the matrix used.

TN is the most common type of LCD TFT screen. This type of matrix has gained such popularity due to its unique features. With their low cost, they have quite high performance, and in some moments, such TN screens even have advantages over other types of matrices.

In addition, manufacturers of mobile phones, smartphones, tablet PCs and laptops are increasingly choosing IPS TFT LCD modules, paying attention to excellent color reproduction, good viewing angles, as well as economical power consumption, which is extremely important for mobile devices.

Super LCD is a screen technology that is widely used by manufacturers of modern smartphones and tablet PCs. In fact, Super LCDs are the same IPS matrices that have received a new marketing name and some improvements.

The main difference between such matrices is that they do not have an air gap between the outer glass and the picture (image). Thanks to this, it was possible to achieve a reduction in glare. In addition, visually, the image on such displays seems closer to the viewer. When it comes to touch screens on smartphones and tablet PCs, Super LCD screens are more sensitive to touch and more responsive to movements.

In turn, LCD TFT displays include the SLCD matrix type. Thus, Super LCD is a type of active matrix TFT display. At the very beginning of this publication, we already said that TFT and LCD have no difference, they are basically the same thing.

All modern matrices have fairly high performance, so ordinary users may not even notice the difference, because IPS matrices are practically not inferior to TN in response time, and TN, in turn, have rather large viewing angles. In addition, as a rule, the user is located opposite the screen, and not on the side or on top, which is why large angles are not required in principle. But the choice is still yours.

Technology does not stand still, and the production of liquid crystal screens is no exception. However, due to the constant development and release of new technologies in the manufacture of screens, as well as due to special marketing approaches to advertising, many buyers may have a question when choosing a monitor or TV, which is better than an IPS or TFT screen?

To answer this question, you need to understand what IPS technology is and what a TFT screen is. Only knowing this, you will be able to understand the difference between these technologies. This in turn will help you to right choice screen that will fully meet your requirements.

As you may have guessed, TFT is the short name for technology. It completely looks like this - Thin Film Transistor, which in translation into Russian means a thin film transistor. Basically, a TFT display is a type of liquid crystal display that is based on an active matrix. In other words, this is a conventional active matrix LCD screen. That is, the control of liquid crystal molecules occurs with the help of special thin-film transistors.

IPS is also short for In-Plane Switching. This is a kind of active matrix LCD display. This means that the question of which is better TFT or IPS is erroneous, since they are essentially the same thing. To be more precise, IPS is a type of FTF display matrix.

Thus, it becomes obvious that the difference between TFT and IPS lies only in the fact that TFT is a type of LCD screen with an active matrix, and IPS is the same active matrix in a TFT display, or rather, one of the types of matrices. It should be noted that such a matrix is ​​the most common among users around the world.

The common misconception that there is any difference between TFT and IPS has arisen due to marketing ploys sales managers. In an attempt to attract new customers, marketers do not disseminate complete information about technologies, which allows you to create the illusion that a completely new development is coming out into the world. Of course, IPS is more new development than TN, however, it is impossible to choose which TFT or IPS display is better for the above reasons.

TFT is a technology in which the crystals in the display are arranged in a spiral and at the maximum possible voltage, they rotate so that the screen shows black, if there is no voltage we will see White color. It is usually used in budget models, for example. Such displays cannot produce perfect black, the output is dark gray.

Simply put, IPS technology is an advanced TFT technology that displays blacks much better and makes the picture on the display more contrast than in TFT screens. IPS screens work a little slower, however, the user does not notice this and this feature can only be revealed as a result of technological tests.

A more priority use of TFT displays is seen in simple phones that a person buys to make calls, and not to sit in contact, here"s another example of a dialer. The advantage lies in much lower power consumption than in IPS displays. But a modern smartphone with a simple TFT display can be seen less and less.

Don"t be surprised if in technical specifications expensive smartphone you will see the abbreviation TFT, it can be an IPS display, because IPS is a type of TFT like AMOLED and Super AMOLED.

Derivative technologies have emerged from IPS and TFT. For IPS, these are Super IPS and UA-IPS - by and large the same thing, but with some improvements. For TFT, this is TN + Film - capable of better tint reproduction.

The difference between image quality in IPS and just TFT is striking. When tilted, a regular TFT without IPS technology turns black so that it"s impossible to make out anything, but with IPS it stays as if nothing had happened, it"s amazing what technology has come to)

For many, liquid crystal displays (LCD) are associated primarily with flat-panel monitors, "cool" TVs, laptops, camcorders and cell phones. Some will add PDAs, electronic games, ATMs here. But there are still many areas where displays with high brightness, rugged construction, and operation over a wide temperature range are needed.

The constant development of technologies in this area has made it possible to reduce the cost of LCD production to a level at which a qualitative transition has taken place: expensive exotics have become commonplace. Ease of use has also been an important factor in the rapid adoption of LCD displays in the industry.

This article covers the main options various types liquid crystal displays, which will allow you to make an informed and correct choice of LCD for each specific application (the "bigger and cheaper" method is almost always too expensive).

The whole variety of LCD displays can be divided into several types depending on the production technology, design, optical and electrical characteristics.

The principle of operation and the "sandwich" structure of all TFT LCDs is approximately the same (Fig. 2). Light from a backlight (neon or LED) passes through the first polarizer and enters a layer of liquid crystals driven by a thin film transistor (TFT). The transistor creates an electric field that shapes the orientation of the liquid crystals. After passing through such a structure, the light changes its polarization and will either be completely absorbed by the second polarizing filter (black screen), or will not be absorbed (white), or absorption will be partial (colors of the spectrum). Image color define color filters(similar to cathode ray tubes, each pixel of the matrix consists of three subpixels - red, green and blue).

Color filters for red, green and blue flowers integrated into the glass base and placed close to each other. It can be a vertical stripe, a mosaic structure, or a delta structure (Fig. 3). Each pixel (dot) consists of three cells of the specified colors (subpixels). This means that at m x n resolution, the active matrix contains 3m x n transistors and subpixels. The pixel pitch (with three sub-pixels) for a 15.1" TFT LCD (1024 x 768 dots) is approximately 0.30 mm, and for an 18.1" (1280 x 1024 dots) is 0.28 mm. TFT LCDs have a physical limitation, which is determined by the maximum screen area. Don"t expect 1280 x 1024 resolution at 15" diagonal and 0.297mm dot pitch.

On the close range the points are clearly distinguishable, but it does not matter: when forming the color, the property of the human eye is used to mix colors at an angle of view of less than 0.03 °. At a distance of 40 cm from the LCD, with a 0.1 mm sub-pixel pitch, the viewing angle will be 0.014° (the color of each sub-pixel can only be distinguished by a person with eagle vision).

TN (Twist Nematic) TFT or TN+Film TFT is the first technology that appeared on the LCD market, the main advantage of which is low cost. Disadvantages: black color is more like dark gray, which leads to low image contrast, "dead" pixels (when the transistor fails) are very bright and noticeable.

IPS (In-Pane Switching) (Hitachi) or Super Fine TFT (NEC, 1995). It is characterized by the largest viewing angle and high color accuracy. The viewing angle is extended to 170°, the rest of the functions are the same as those of TN + Film (response time is about 25ms), almost perfect black color. Advantages: good contrast, "dead" pixel - black.

The design of the liquid crystal display is determined by the arrangement of layers in the "sandwich" (including the light guide layer) and has highest value for the quality of the image on the screen (in any conditions: from a dark room to working in sunlight). Three main types of color LCDs are currently in use:

Transmissive display type (transmissive). In this type of design, light enters through a liquid crystal panel from the back (backlight) (Figure 4). Most of the LCDs used in laptops and PDAs are made using this technology. The Transmissive LCD has a high image quality indoors and a poor (black screen) in sunlight as the sun"s rays reflected from the screen surface completely suppress the light emitted by the backlight. This problem is (currently) solved in two ways: increasing the brightness of the backlight and reducing the amount of reflected sunlight.

To work in daylight in the shade, a backlight is required that provides 500 cd / m2, in direct sunlight - 1000 cd / m 2. Brightness of 300 cd/m 2 can be achieved by increasing the brightness of one CCFL (Cold Cathode Fluorescent Lamp) lamp to the limit or by adding a second lamp located opposite. LCD models with increased brightness use from 8 to 16 lamps. However, increasing the brightness of the backlight increases the consumption of battery power (one backlight consumes about 30% of the power used by the device). Therefore, screens with increased brightness can only be used when an external power supply is available.

Reducing the amount of reflected light is achieved by applying an anti-reflection coating to one or more layers of the display, replacing the standard polarizing layer with a minimally reflective one, and adding films that increase brightness and thus increase the efficiency of the light source. In Fujitsu LCDs, the converter is filled with a liquid with a refractive index equal to that of the touch panel, which greatly reduces the amount of reflected light (but greatly affects the cost).

Translucent display type (transflective) similar to transmissive, but between the layer of liquid crystals and the backlight there is a so-called. partially reflective layer (Fig. 5). It can be either partially silver, or completely mirrored with many small holes. When such a screen is used indoors, it works similarly to a transmissive LCD in which some of the light is absorbed by the reflective layer. In daylight, sunlight reflects off the specular layer and illuminates the LCD layer, with the light passing through the liquid crystals twice (in and then out). As a result, image quality in daylight is lower than in artificial lighting indoors when the light passes the LCD once.

Reflective display type(reflective) has a fully reflective specular layer. All illumination (sunlight or front light) (Figure 6) passes through the LCD, reflects off the specular layer, and passes through the LCD again. In this case, the image quality of reflective displays is lower than that of semi-transmissive displays (because both use similar technologies). Indoors, the front illumination is not as effective as the backlight, and therefore the image quality is lower.

The ISO 13406-2 standard defines limits for the number of defective pixels per million. According to the table, LCD panels are divided into 4 classes.

Brightness- the advantage of the LCD display, which is on average twice as high as the CRT indicators: with an increase in the intensity of the backlight, the brightness immediately increases, and in the CRT it is necessary to increase the flow of electrons, which will lead to a significant complication of its design and increase electromagnetic radiation. The recommended brightness value is not less than 200 cd/m 2 .

LCD displays as sensors. The reduction in cost and the emergence of LCD models operating in harsh operating conditions made it possible to combine in one person (in the face of a liquid crystal display) a means of outputting visual information and a means of entering information (keyboard). The task of building such a system is simplified by using a serial interface controller, which is connected, on the one hand, to the LCD display, and on the other hand, directly to the serial port (COM1 - COM4) (Fig. 7). To control, decode signals and suppress "bounce" (if you can call it a touch detection), a PIC controller (for example, IF190 from Data Display) is used, which provides high speed and accuracy in determining the touch point.

Let"s complete the theoretical research on this and move on to the realities of today, or rather, to what is now available on the liquid crystal display market. Among all TFT LCD manufacturers, consider NEC, Sharp, Siemens and Samsung. The choice of these firms is based on

The list of available LCD panels for industrial applications (the backlight inverter is supplied separately) is shown in Table 2, and the block diagram (using the NL6448BC26-01 10-inch display as an example) is shown in Fig. eight.

Played a significant role in the development of LCD-technologies. Sharp is still among the technology leaders. The world"s first calculator CS10A was produced in 1964 by this corporation. In October 1975, the first compact digital watch was made using TN LCD technology. In the second half of the 70s, a transition began from eight-segment liquid crystal indicators to the production of matrices with addressing each point. In 1976, Sharp released a 5.5-inch black-and-white TV set based on an LCD matrix with a resolution of 160x120 pixels. A short list of products is in table 3.

The company produces liquid crystal displays under the brand name "Wiseview™". Starting with the release of a 2-inch TFT panel to support the Internet and animation in mobile phones, Samsung now produces a range of displays from 1.8" to 10.4" in the small and medium TFT LCD segment, with some models designed to operate at natural light(table 5).

Currently, the choice of liquid crystal display model is determined by the requirements of a particular application and, to a much lesser extent, by the cost of LCD.