Matrix type ips or tft. IPS or TFT - which is better? Which screen type is best to choose?

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For many, liquid crystal displays (LCDs) are associated primarily with flat-panel monitors, “cool” TVs, laptops, video cameras and cell phones. Some will add PDAs, electronic games, and ATM machines here. But there are many other areas where displays with high brightness, rugged construction, and operating over a wide temperature range are needed.

Flat displays have found application where minimum power consumption, weight and dimensions are critical parameters. Mechanical engineering, automobile industry, railway transport, offshore drilling rigs, mining equipment, outdoor retail outlets, avionics, marine, special vehicles, security systems, medical equipment, weapons - this is not a complete list of applications of liquid crystal displays.

The constant development of technology in this area has made it possible to reduce the cost of LCD production to a level at which a qualitative transition has occurred: expensive exotics have become commonplace. An important factor rapid spread LCD displays have become popular in the industry and are easy to use.

This article covers the main parameters various types liquid crystal displays, which will allow you to make informed and correct LCD selection for each specific application (the “bigger and cheaper” method almost always turns out to be too expensive).

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

Technology

Currently, two technologies are used in LCD production (Fig. 1): passive matrix (PMLCD-STN) and active matrix (AMLCD).

MIM-LCD and Diode-LCD technologies are not widely used and therefore we will not waste time on them.

Rice. 1. Types of liquid crystal display technologies

STN (Super Twisted Nematic) is a matrix consisting of LCD elements with variable transparency.

TFT (Thin Film Transistor) is an active matrix in which each pixel is controlled by a separate transistor.

Compared to a passive matrix, TFT LCD has higher contrast, saturation, and shorter switching times (there are no “tails” for moving objects).

Brightness control in a liquid crystal display is based on the polarization of light (general physics course): light is polarized when passing through a polarizing filter (with a certain polarization angle). In this case, the observer sees only a decrease in the brightness of the light (almost 2 times). If another such filter is placed behind this filter, the light will be completely absorbed (the polarization angle of the second filter is perpendicular to the polarization angle of the first) or completely transmitted (the polarization angles are the same). With a smooth change in the polarization angle of the second filter, the intensity of the transmitted light will also change smoothly.

The operating principle and “sandwich” structure of all TFT LCDs are approximately the same (Fig. 2). Light from a backlight (neon or LED) passes through the first polarizer and enters a layer of liquid crystals controlled by a thin film transistor (TFT). The transistor creates an electric field that shapes the orientation of the liquid crystals. Having passed 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 (spectrum colors). The color of the image is determined by color filters (similarly cathode ray tubes, each pixel of the matrix consists of three subpixels - red, green and blue).

Rice. 2. TFT LCD structure

Pixel TFT

Color filters for red, green and blue are integrated into the glass base and placed close to each other. It could be vertical stripe, mosaic structure or delta structure (Fig. 3). Each pixel (point) 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 pixels) is approximately 0.30 mm, and for 18.1" (1280 x 1024 pixels) it 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 with a 15" diagonal and 0.297mm dot pitch.

Rice. 3. Color filter structure

At a close distance, the dots are clearly distinguishable, but this is not a problem: when forming color, the ability of the human eye to mix colors at a viewing angle of less than 0.03° is used. At a distance of 40 cm from the LCD display, with a pitch between subpixels of 0.1 mm, the visual angle will be 0.014° (the color of each subpixel can only be distinguished by a person with eagle vision).

Types of LCD Displays

TN (Twist Nematic) TFT or TN+Film TFT is the first technology to appear on the LCD display market, the main advantage of which is its 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). Characterized by the largest viewing angle and high color accuracy. The viewing angle is expanded to 170°, other functions are the same as TN+Film (response time about 25ms), almost perfect black color. Advantages: good contrast, “dead” pixel is black.

Super IPS (Hitachi), Advansed SFT (manufacturer - NEC). Advantages: bright contrast image, almost invisible color distortion, increased viewing angles (up to 170° vertically and horizontally) and exceptional clarity.

UA-IPS (Ultra Advanced IPS), UA-SFT (Ultra Advanced SFT) (NEC). Reaction time is sufficient to ensure minimal color distortion when viewing the screen from different angles, increased panel transparency and expansion color range at a sufficiently high brightness level.

MVA (Multi-Domain Vertical Alignment) (Fujitsu).The main advantage is least time reactions and high contrast. The main disadvantage is the high cost.

PVA (Patterned Vertical Alignment) (Samsung). Microstructural vertical placement of liquid crystals.

Design

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

transmissive, intended mainly for equipment operating indoors;
reflective is used in calculators and watches;
projection (projection) is used in LCD projectors.

A compromise type of transmissive display type for operation both indoors and with external lighting is a translucent type of design.

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

Rice. 4. Transmission type liquid crystal display design

To work in daylight in the shade, a backlight lamp is required that provides 500 cd/m2, in direct sunlight - 1000 cd/m2. A brightness of 300 cd/m2 can be achieved by maximizing the brightness of one CCFL (Cold Cathode Fluorescent Lamp) lamp or by adding a second lamp located opposite. Models of liquid crystal displays with increased brightness use from 8 to 16 lamps. However, increasing the brightness of the backlight increases battery power consumption (one backlight lamp consumes about 30% of the energy used by the device). Therefore, high-brightness screens can only be used if there is external source nutrition.

Reducing the amount of reflected light is achieved by applying an anti-reflective 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 LCD displays, the converter is filled with a liquid with a refractive index equal to the refractive index touchpad, which significantly reduces the amount of reflected light (but greatly affects the cost).

Translucent display type (transflective) similar to transmitting, but it has a so-called between the layer of liquid crystals and the backlight. 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 part of the light is absorbed by a reflective layer. In daylight, sunlight reflects off the mirror layer and illuminates the LCD layer, causing the light to pass through the liquid crystals twice (inward and then outward). As a result, image quality in daylight is lower than in artificial lighting indoors when the light passes through the LCD once.

Rice. 5. Translucent type liquid crystal display design

The balance between image quality indoors and in daylight is achieved by selecting the characteristics of the transmitting and reflective layers.

Reflective display type(reflective) has a completely reflective mirror layer. All illumination (sunlight or front light) (Fig. 6) passes through the LCD, is reflected from the mirror layer and passes through the LCD again. In this case, the image quality of reflective type displays is lower than that of semi-transmissive ones (since both cases use similar technologies). Indoors, front lighting is not as effective as back lighting, and, accordingly, image quality is lower.

Rice. 6. Reflective type liquid crystal display design

Basic parameters of liquid crystal panels

Permission. A digital panel, the number of pixels in which strictly corresponds to the nominal resolution, must scale the image correctly and quickly. A simple way to check the quality of scaling is to change the resolution (text written on the screen small print). It is easy to notice the quality of interpolation by the contours of the letters. A high-quality algorithm produces smooth, but slightly blurry letters, while fast integer interpolation necessarily introduces distortions. Performance is the second resolution parameter (scaling one frame requires interpolation time).

Dead pixels. On a flat panel, several pixels may not work (they are always the same color), which appear during the production process and cannot be restored.

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.

Table 1

Type 1 - constantly glowing pixels (white); Type 2 - "dead" pixels (black); Type 3 - defective red, blue and green subpixels.

Viewing angle. The maximum viewing angle is defined as the angle from which the image contrast decreases by 10 times. But first of all, when the viewing angle changes from 90 (color distortions are visible. Therefore, the larger the viewing angle, the better. There are horizontal and vertical viewing angles, recommended minimum values- 140 and 120 degrees, respectively (the best viewing angles are provided by MVA technology).

Response time(inertia) - the time during which the transistor manages to change the spatial orientation of liquid crystal molecules (the less, the better). To ensure that fast-moving objects do not appear blurry, a response time of 25 ms is sufficient. This parameter consists of two values: the time to turn on the pixel (come-up time) and the time to turn off (come-down time). Response time (more precisely, turn-off time as the longest time during which an individual pixel changes its brightness to its maximum) determines the refresh rate of the image on the screen

FPS = 1 sec/response time.

Brightness- the advantage of an LCD display, which is on average two times higher than that of a CRT: with an increase in the intensity of the backlight, the brightness immediately increases, and in a 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 at least 200 cd/m2.

Contrast is defined as the ratio between maximum and minimum brightness. The main problem is the difficulty of obtaining a black point, because The backlight is constantly on and the polarization effect is used to obtain dark tones. The black color depends on the quality of the overlap of the backlight luminous flux.

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

Rice. 7. Block diagram of TFT LCD using the example of NL6448BC-26-01 display from NEC

Let’s complete the theoretical research here and move on to the realities of today, or more precisely, to what is now available on the liquid crystal display market. Among all TFT LCD manufacturers, consider products from NEC, Sharp, Siemens and Samsung. The choice of these companies is due to

leadership in the market of LCD displays and TFT LCD production technologies;
availability of products on the market of the CIS countries.

NEC Corporation has been producing liquid crystal displays (20% of the market) almost since their introduction and offers not only wide choose, but also various options versions: standard (Standard), special (Special) and special (Specific). Standard option - computers, office equipment, home electronics, communication systems, etc. The special design is used in transport (any: land and sea), traffic control systems, security systems, medical equipment (not related to life support systems). Designed for weapons systems, aviation, space equipment, nuclear reactor control systems, life support systems and other similar special option execution (it is clear that this is not cheap).

The list of manufactured LCD panels for industrial use (the inverter for the backlight is supplied separately) is given in Table 2, and the block diagram (using the example of a 10-inch display NL6448BC26-01) is shown in Fig. 8.

Rice. 8. Display appearance

Table 2. Models of NEC LCD panels

Model	Diagonal size, inch	Number of pixels	Number of colors	Description
NL8060BC31-17	12,1	800x600	262144	High brightness(350cd/m2)
NL8060BC31-20	12,1	800x600	262144	Wide viewing angle
NL10276BC20-04	10,4	1024x768	262144	-
NL8060BC26-17	10,4	800x600	262144	-
NL6448AC33-18A	10,4	640x480	262144	Built-in inverter
NL6448AC33-29	10,4	640x480	262144	High brightness, wide viewing angle, built-in inverter
NL6448BC33-46	10,4	640x480	262144	High brightness, wide viewing angle
NL6448CC33-30W	10,4	640x480	262144	Without backlight
NL6448BC26-01	8,4	640x480	262144	High brightness (450 cd/m2)
NL6448BC20-08	6,5	640x480	262144	-
NL10276BC12-02	6,3	1024x768	16, 19M	-
NL3224AC35-01	5,5	320x240	Full color
NL3224AC35-06	5,5	320x240	Full color	Separate NTSC/PAL RGB input, built-in inverter, slim
NL3224AC35-10	5,5	320x240	Full color	Separate NTSC/PAL RGB input, built-in inverter
NL3224AC35-13	5,5	320x240	Full color	Separate NTSC/PAL RGB input, built-in inverter
NL3224AC35-20	5,5	320x240	262, 144	High brightness (400 cd/m2)

Played a significant role in the development of LCD technologies. Sharp is still one of 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 produced using TN LCD technology. In the second half of the 70s, the transition began from eight-segment liquid crystal displays to the production of matrices with addressing of each point. In 1976, Sharp released a black-and-white TV with a 5.5-inch screen diagonal, based on an LCD matrix with a resolution of 160x120 pixels. A short list of products is in Table 3.

Table 3. Sharp LCD panel models

Produces active matrix liquid crystal displays based on low-temperature polysilicon thin-film transistors. The main characteristics of 10.5" and 15" displays are shown in Table 4. Pay attention to the operating temperature range and shock resistance.

Table 4. Main characteristics of Siemens LCD displays

Notes:

I - built-in inverter l - in accordance with the requirements of the MIL-STD810 standard

The company produces liquid crystal displays under the "Wiseview™" brand. Starting with a 2-inch TFT panel to support 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 for use in natural light ( table 5).

Table 5. Main characteristics of Samsung LCD displays of small and medium sizes

Notes:

LED - light-emitting diode; CCFL - cold cathode fluorescent lamp;

The displays use PVA technology.

Conclusions.

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

First some terminology

TFT-LCD(Thin-Film Transistor Liquid-Crystal Display) - liquid crystal display using thin-film transistors. This is the correct name for the most common ones today. LCD monitors, based on a matrix with controlled thin-film transistors.

CRT (Cathode-Ray Tube) is a cathode ray tube, this is the same as the familiar “CRT” (cathode ray tube).

Where it all started

LCD monitors today you can find it anywhere – in the offices of serious companies, in the dentist’s waiting room, on the desk of a government official, and even in the homes of your friends. But not so long ago, such a monitor cost thousands of dollars and was the lot of only very wealthy people and very “cool” offices.

Although, if you think about it, the history of liquid crystal displays goes back more than a hundred years. No, of course, not the devices themselves for displaying visual information from a computer, but their basis - the so-called liquid crystals. They were discovered, as often happens in science, completely unintentionally.

In 1888, the Austrian botanist Friedrich Reinitzer investigated the properties of cholesterol benzonate. He discovered that when heated, the crystal softened and subsequently turned into a real liquid. He shared his discovery with the German physicist Otto Lehmann, who discovered some properties of crystals, especially when illuminated. This is where the name given by Otto Lehmann, “liquid crystal” comes from.

Liquid crystals are almost completely transparent substances that have properties inherent in both liquids and solids. Light passing through liquid crystals acquires polarization in accordance with the orientation of the molecules, which is a property inherent in solid substances - crystals. And in the 60s of the 20th century it was discovered that when applied to liquid crystals electrical voltage the orientation of the molecules changes - a typical property of a liquid.

How does an LCD monitor work?

The light from the backlight first passes through a polarizing filter, acquiring polarization. The light then passes through the translucent control electrodes and reaches the liquid crystal layer. By changing the control voltage, the polarization of the light flux can be changed by a value from 0 to 90 degrees. After the layer of liquid crystals, light filters are located and here each point is painted in the desired color - red, green or blue. If we look at the screen without a polarizing filter, we will not see color differences, because our eyes cannot distinguish the polarization of light.

In the beginning, the matrices that controlled liquid crystals were “passive”. They could only control all three base pixels together (red, blue and green). And only after some time, the production technology of LCD monitors switched to the use of LCD panels with an active matrix. In them, each subpixel was controlled separately. This made it possible to increase the number of shades reproduced by the monitor tens of times – up to more than 16 million.

LCD monitor technologies

The very first technology used to make active LCD monitors. It has been worked out to the finest detail, so the cost of the matrices is the lowest. The abbreviation TN+Film stands for Twisted Nematic + Film. IN normal condition, in the absence of control voltage, the liquid crystals in TN+Film are in the twisted phase and the subpixel burns brightly. The greater the voltage applied to the cell, the more the liquid crystal molecules straighten. At maximum control voltage, the subpixel will be darkened to the limit. This technology has several disadvantages. Firstly, each pixel will never be completely dark and the black color will not be perfect. Secondly, if the control of even one subpixel fails, an unpleasant luminous dot forms on the screen, and thirdly, the viewing angle, despite the special coating film, rarely exceeds 140-150 degrees.

In-Plane Switching is a technology developed by Hitachi and NEC. A distinctive feature is that both control translucent electrodes are located in the same plane - only on the bottom side of the LCD cell. The liquid crystals are arranged differently than in the case of TN+Film: in a relaxed state, they do not transmit light. The higher the control voltage, the more the crystals twist the polarization of the light beam. In addition, IPS matrices have a larger viewing angle than TN+Film. But this technology also has a significant drawback - big time subpixel response - up to 50 ms.

Fujitsu's patented technology is called Multi-Domain Vertical Alignment. Liquid crystal molecules are oriented in the vertical direction (Vertical Alignment) and in the absence of control voltage do not change the polarization of the light flux. Due to the design features (long, vertically oriented chains of crystals), when the viewing angle changes, the light output of the subpixel (and therefore the color of the resulting pixel) can change significantly. Therefore, each subpixel is divided into several zones (Multi-Domain), each of which is optimized for the best light output in its viewing sector. In this original way, the problem of severely limited viewing angles in the original VA technology was solved.

MVA matrices have all the advantages of IPS technology (deep black background color, dark color of dead pixels, wide viewing angles), but at the same time they have better reaction speed. But there are also disadvantages - such a panel changes sharp color transitions faster, and smooth ones much more slowly. There is a special type of this technology - PVA (Patterned Vertical Alignment) from Samsung. Today MVA is the most popular technology in the market.

What are the advantages of TFT over CRT?

Let's start with geometry. The clarity and accuracy of the image on an LCD monitor is much higher than that of a conventional cathode-ray monitor. LCD monitors have ideal geometry due to the matrix production technology. With a CRT, using the existing settings, you can achieve good accuracy of geometric characteristics, but still, they will be somewhat worse than those of an LCD monitor.

Next, let's take a look at the mixing. The term “convergence” means the convergence at one point of its three components - red, green and blue (RGB). A white dot on a dark background of the screen should be exactly white, and not split into three different colors. Here again, LCD monitors are in the lead. It may not be true to talk about perfect mixing of LCD monitors. It’s just that in this case the distances between the subpixels are constant and quite small, and most importantly, you don’t need to think about adjusting the convergence of the LCD matrix and choose a well-adjusted copy (as is the case with CRT monitors). For CRT monitors it is much more difficult to ensure uniform, stable convergence over the entire screen area, because this is an analog device with three electron guns spaced apart in space. To obtain good information, ingenious compensation and adjustment schemes, as well as complex designs of deflection systems, are used.

A little about focusing. Good focusing implies a minimum size of an individual pixel and clearly defined edges. If the monitor is properly focused, the edges of small objects will be sharp and clear, without excessive blurriness. LCD matrices, by virtue of the very principle of their operation, always have perfect focusing: each pixel (subpixel) is an even rectangle with clearly defined boundaries. A CRT monitor can be adjusted to very good focusing performance, but this requires painstaking adjustment and selection of a successful picture tube along with a deflection system.

But not everywhere an LCD monitor can be better than its CRT counterpart. A sore point for all computer designers is color rendering. Correct color rendering implies that the color displayed on the monitor accurately matches the original color. Moreover, such accuracy must be ensured over the entire color range available to the monitor. Unlike CRT competitors, TFT-LCDs can display a very limited number of colors, they generally have unsatisfactory grayscale linearity, and, most unpleasantly, color rendition varies greatly when the observer deviates to the right or left

The next disappointing point for LCD monitors is support for different resolutions. LCD monitors are not designed to support different resolutions; complex approximation or interpolation algorithms are used for resolutions other than native ones. A good result is achieved only in the physical resolution of the matrix. CRT monitors, on the contrary, are perfectly adapted to a wide variety of graphics modes, and as the resolution decreases, the clarity only increases.

But LCD monitors have several more positive aspects, looking at which, only the price of these monitors can deter you from buying. These include much smaller dimensions (and therefore ease of placement on the table and ease of transportation), and noticeably lower energy consumption (and therefore savings on electricity), and a lower level of harmful electromagnetic radiation, and lower sensitivity to magnetic fields.

One may also recall the fact that in Lately The performance of LCD monitors has improved significantly in all areas of weakness. The angles that can be viewed on the monitor have become wider, the image has more contrast, color rendition is clearer and more realistic, the pixel response speed is higher and, most importantly, the price is more affordable.

Having once won their positions in the computer monitor market, liquid crystal displays are not only not going to retreat from them, but are also taking up new ones with all their might, winning their place on the desktops of both corporate and home users.

TFT technology is used to create displays for all kinds of electrical appliances, including TVs, tablets, computer monitors, mobile phones, navigators, etc. Undoubtedly, the screen in such devices plays an important role, so before purchasing equipment and gadgets, it is worth understanding the intricacies of their manufacture. The design of the display determines the quality and clarity of the image, viewing angle, and color reproduction. In some cases, these parameters are of great importance.

Concept of TFT display

TFT LCD is a type of active matrix liquid crystal display. Each pixel of such displays is controlled by 1-4 thin film transistors (in English - Thin Film Transistor, abbreviated as TFT), which help to easily turn on / off the LEDs, creating a clearer, high quality image.

The TFT display has two glass substrates, inside of which there is a layer of liquid crystals. The front glass backing contains a color filter. The back substrate contains thin transistors arranged in columns and rows. Behind everything is a backlight.

Interesting to know: Each pixel is a small capacitor with a layer of liquid crystal sandwiched between transparent conductive layers of indium tin oxide. When the display turns on, the molecules in the liquid crystal layer bend at a certain angle and allow light to pass through. This creates the pixel we see. Depending on the angle of bending of liquid crystal molecules, one color or another appears. All pixels together form a picture.

A standard TFT monitor has 1.3 million pixels, each of which controls its own transistor. They consist of thin films of amorphous silicon deposited on glass using PECVD technology (this method is usually used to create microprocessors). Each element operates on a small charge, so the image is redrawn very quickly, the image is updated many times per second.

Is it worth buying equipment with TFT displays?

Displaying moving images on a large LCD display is challenging because it requires changing the state of a large number of liquid crystals in a fraction of a second. In passive matrix LCDs, transistors are located only at the top and left of the screen. They control entire rows and columns of pixels. In such devices, crosstalk can occur due to the fact that the signal sent to one pixel affects its “neighbors”. Because of this, we see slowdown or blurring of the picture.

TFT displays do not have this problem. Installing a control device in the form of a thin film transistor directly on the pixel prevents the blurring effect during video playback. The unidirectional current flow characteristic prevents the charges of multiple LEDs from merging. Therefore, today Thin Film Transistor technology has become the standard for LCD screen production. What other advantages does it have?

TFT allows you to get a stable, fairly high-quality image with a good viewing angle. In this case, it is possible to produce a screen of different sizes with different resolutions(from a calculator or smart watch to a TV on the entire wall).
Such screens have bright backlighting, which is important for mobile phones and computers. Bright LED backlights provide greater adaptability and can be adjusted based on the user's visual preferences. Some devices have a function to automatically adjust the brightness level depending on the lighting.
The advantages of TFT over older CRT monitors are obvious. CRTs are bulky, dim and small. CRTs generate a large amount of heat, as well as electromagnetic radiation, which negatively affects vision. TFT matrices are safe in this regard.
TFT screens have a fairly competitive price, although this method is used to produce not only budget devices, but also professional, expensive equipment.

At first glance it looks tempting. However, before you buy, you need to know: there are several types of TFT displays and they have different characteristics.

Types of TFT displays, their advantages and disadvantages

Names such as TN, IPS and MVA are all TFT displays. It's easy to get confused by these names. Let's try to figure out how they differ, and what is better.

Tweeted Nematic (TN) + Film

It is simpler, cheaper and quick option. The response time of the TFT TN screen matrix is only 2-4 ms. They can display more frames per second, which is especially important when watching videos and playing video games.

However, TN-based devices have many disadvantages in terms of image quality:

The viewing angle of a TN display is only 50-90°. This means that you can only get the full effect of graphics on a screen made using TFT TN technology by looking at it directly. If you look from the side, above or below, the picture will change its color;
low contrast ratios (maximum 500:1) and a small range of colors. Such a device will not convey all colors;
The blacks in TN screens are too bright and lack depth, and the whites are not bright enough, meaning that nothing will be visible in sunlight.

If you use the device for regular web browsing, office work or other daily tasks, then a display with TFT TN technology will suit your needs. It is also suitable for gamers, since the image transmission speed is still more important during gaming. But for business or graphics work that requires the highest levels of color and graphic accuracy, your best bet is to choose a display with IPS technology.

Super TFT (or IPS)

IPS TFT technology solves all the problems of TN screen. The main difference from TN panels is the direction of movement of the crystals. In IPS displays, they move parallel to the panel plane, rather than perpendicular to it. This change reduces light scattering in the matrix and allows for wider viewing angles (from 170°), a large color spectrum (up to 1 billion), and high contrast (1:1000). Blacks will be deeper and more refined.

However, IPS also has a drawback: the response time of such matrices is 10-20 ms, which is not enough for modern video games, although acceptable. AMOLED screens have even longer response times.

I can't say which is better: IPS technology or TN TFT. Each of them has pros and cons, so you need to proceed from the purpose for which you are buying the device. IPS is widely used in high-end monitors aimed at professional graphic artists.

MVA

This technology is the most advanced - it combines the advantages of the two previous options. MVA displays have a wide viewing angle, excellent color and contrast, deep black color and at the same time optimal time response.

If you compare displays with TFT IPS and SVA technology (a type of MVA), it will be difficult to choose the best option. Everyone has merits. SVA has only a slight difference in structure - in such a display the crystals are aligned vertically rather than horizontally. This affects their ability to transmit or block light, which determines the display's brightness level and black output. In SVA displays, these parameters are at their best, although this does not mean that IPS shows a bad picture. Compared to IPS, SVA has a smaller viewing angle.

Flaws

Thin film transistors are very sensitive to voltage fluctuations and mechanical stress. They can be easily damaged, resulting in the formation of “dead” pixels – dots without an image. However, AMOLED screens, which are now gaining popularity, are even more fragile. From reboot or mechanical damage they stop working completely.

Another small minus is the thickness of the TFT display. Due to the additional layer, it will be slightly thicker than the thickness of a plasma panel, regular LCD or AMOLED. However, the TFT screen is quite compact.

Another relative disadvantage of the technology is its higher energy consumption when compared to other types of screens. But again, TFT displays are economical enough for everyday use.

IPS or TFT - which is better to choose? More recently, I was faced with the need to give a person a reasonable answer to this question when buying a tablet. Knowing for sure what was already on everyone’s lips, I was ready to immediately give an answer. But still, I decided to study this topic a little in order to support what was said with compelling arguments. I had to dig through the information a little and even... To understand the situation, I’ll say right away that we were talking about buying a reliable used tablet. As it turned out, this also contributes to the final decision regarding what is better - IPS or TFT matrix. Even if you need to buy new tablet or smartphone, the information below will also be relevant and useful. So, let's begin our short review.

A little about the technologies used to produce IPS screens

Although most modern displays use liquid crystals, each case may use slightly different technologies, resulting in differences in the performance of the final product. Terminology used throughout may vary. Therefore, in order not to be misled regarding TFT or IPS monitors, the following should be noted.

First and foremost, let's separate the weeds from the chaff: IPS technology is no different than TFT. It is TFT – or rather, one of its implementations. On the other hand, "our" person called TFT understands TFT-TN.

Thus, the comparison is made between two representatives of TFT matrices: IPS or TN. Regarding the technologies used:

TFT (we understand that we are talking about TFT-TN). Liquid crystal display (thin film transistors). The crystals are arranged spirally in the matrix body between two plates. The formation of an image occurs due to the rotation of the crystal molecules. If there is no voltage, their horizontal rotation angle is 90 degrees, while they have White color. At the maximum applied voltage, the rotation is carried out at an angle at which, when light passes through the crystal, it turns black. So, depending on the voltage applied to the crystals, they change their color.
IPS (actually TFT-IPS). The same crystals, only their location is parallel to each other. When there is no voltage, the crystal molecules are not rotated.

Now let's move on to the main question: ? Which display should you choose?

IPS or TFT - which is better? Differences between screens in image quality

The key features of any monitor, display, IPS or TFT screen are, first of all, determined by the quality of the picture display. In turn, quality can be broken down into indicators such as contrast and viewing angle.

When it comes to the IPS matrix, it significantly outperforms TFT in terms of image contrast. This is achieved by almost perfect reproduction of black crystals. Namely, the display of black directly affects such an indicator as contrast. In TFT displays, individual pixels (when displaying black and other colors) may have a slightly “own” tint, which leads to distortions in the color of the image.

An important factor influencing the choice of screen mobile devices, is the viewing angle. This indicator is especially important if the device is to be used together with others, for example, showing a photo of a recent trip to the sea. With a viewing angle of 178 degrees from any side, the IPS matrix undoubtedly wins, allowing several of your friends or colleagues to enjoy the image without distortion. This is also important to consider when purchasing a particular device.

Reaction speed of IPS and TFT display

The apparent advantage of a TFT display over an IPS screen is its high response speed. Here he has no competitors. At the same time, the IPS matrix needs more time to rotate an array of crystals that are located in parallel.

This fact leads to the obvious conclusion that in devices whose purpose is critical to display speed, it is still better to use TFT. On the other hand, when it comes to everyday use (as a tool for studying, communicating via the Internet and other tasks), this difference is practically invisible to the human eye, and is revealed only through the use of special technical tests. Therefore, when choosing a screen type, in most cases, preference should be given to an IPS matrix.

Which matrix needs more power - IPS or TFT?

There are other differences that we continue to list. How is the energy consumed in batteries of screens made using different technologies? There are obvious differences. The energy consumption of IPS is actually higher. Not only more time, but also more voltage is required to rotate the crystals of this type of matrix. The logical conclusion is increased load to the battery. Therefore, when purchasing used devices, when it is obvious that the battery is no longer new, this fact must be carefully weighed. If you purchase a new phone, tablet or smartphone, and its use involves a long stay out of reach of the mains, it is better to focus on high-quality TFT matrices.

Cost of devices with different types of displays

Price IPS screens always higher. You can pay attention to this by filtering out devices with this type of matrix in any online store. It should be said that IPS is used in almost all modern devices, gradually replacing TFT. At the same time, if you only need the equipment to make a call, what's the point of paying extra for a screen whose benefits won't be used? Moreover, if this increases the overall energy consumption of a smartphone or tablet.

TFT or IPS - which is better? Which matrix should I choose?

So, if you need a modern, high-quality tablet with which you can not only work, but also comfortably show high-quality photos to friends, definitely choose only devices with an IPS matrix. When paying attention to the manufacturers' markings, do not forget that TFT includes both TN and IPS matrices. But this is not all of their types. Knowing which of these two types of matrices is better - TFT or IPS, and wanting to buy a tablet, smartphone or phone, contact any of the trusted online stores (Rozetka, Eldorado, Citrus and others) that provide a full range of these products, with the ability to filter according to the most significant parameters.

By the way, a person who bought a tablet with an IPS matrix, which was delivered to him from Poland, was pleased with it and constantly admires the comfort of using the device even on a sunny day. Facts, they say, are stubborn things.

And again there is a confusion of concepts. If you are trying to determine the difference between monitors or televisions that someone called TFT and LCD, then you have been misled. Try to find the differences between a bus and Ikarus? Between the dog and the neighbor's Bug? Between fruit and apple? That's right, the exercise is useless, because both objects are both at the same time. So it is with screen matrix technologies: LCD is the general name for a class of displays, which includes TFT.

Definition

TFT matrix- active matrix LCD display, made using thin-film transistors.

LCD- a flat display (and a device based on it) based on liquid crystals.

Comparison

LCD displays are not an invention of our century. Screens electronic watch, calculators, instruments, players are also liquid crystal, although they differ significantly from the smartphone or TV screens we are used to. True, at first LCDs were monochrome, but with the development of technology they blossomed in the RGB range. TFT is also a type of LCD display, the production of which is based on an active matrix based on thin-film transistors. If you compare it with the earlier version of LCD, the passive matrix, it becomes obvious that the color quality and response time of TFT is much higher. Twisted polymer is used as crystals in passive matrices. But the energy consumption and cost of passive matrices, called STN, can please anyone. However, monochrome screens in this regard, they will generally look like prize money, but there are unlikely to be many people willing to watch such TVs.

The operating principle of TFT is that each of the thin film transistors controls a single pixel. For each pixel there are three transistors corresponding to the main RGB colors(red, green and blue). The intensity of the light flux depends on the polarization, polarization depends on the application of an electric field to the liquid crystals. TFT involves increasing the level of speed, contrast and clarity of the resulting image.

It is worth noting the disadvantages TFT matrices, eliminated in other technologies. The image quality directly depends on the external lighting of the screen. Transistors at any of the pixels can fail, which leads to the appearance of “dead spots”, or dead pixels. No screen can be protected from this. In addition, TFT matrices are largely energy-intensive, so their use as displays for mobile electronics makes one of the most important properties— autonomy.

Thin-film transistors, which formed the basis for the operation of liquid crystal matrices, have now practically fled to a different camp: OLED screens use them to control their active matrices. There are no longer liquid crystals here, but organic compounds.

Conclusions website

LCD is a type of screen matrix based on liquid crystals.
TFT is a type of active LCD matrix.
TFT makes it different from others LCD technologies use of thin film transistors.
TFT matrices are economical, provide high-quality images, but are energy-intensive.