For a long time I was tormented by the question: what is the difference between the image of modern monitors with TN, S-IPS, S-PVA, P-MVA matrices. My friend and I decided to compare.
For tests, we took two 24 "" monitors (unfortunately, they did not find anything on S-IPS :():
- on a cheap TN matrix Benq V2400W
- on the P-MVA matrix of the middle category Benq FP241W.
Characteristics of candidates:
Benq V2400W
Matrix type: TN + FilmInches: 24"
Permission: 1920x1200
Brightness: 250 cd / m2
Contrast: 1000:1
Response time: 5ms / 2ms GTG
Benq FP241W
Matrix type: P-MVA (AU Optronics)Inches: 24"
Permission: 1920x1200
Brightness: 500 cd / m2
Contrast: 1000:1
Response time: 16ms / 6ms GTG
Trends in recent years
TN (TN + film) matrices improve color rendering, brightness and viewing angles.* VA (S-PVA / P-MVA) matrices improve response time.
How far has progress come?
Already now you can watch films on TN matrices (TN + Film), work with color in editors.* VA play games without motion blur.
But there are still differences.
Brightness
Benq V2400W (TN) has its initial color settings (RGB) set to almost maximum. At the same time, in terms of brightness (at maximum settings), it does not reach * VA (at medium settings). In comparison with other TN monitors, it is indicated that the V2400W has a lower brightness than its competitors (alas, we could not compare :)), but I can say with confidence that the brightness * of VA monitors will be higher than that of TN monitors.In Benq FP241W (* VA), black is also bright due to the brightness of the backlight. For TN, black remained completely black when we compared the on and off states of the monitors. This may not be present on other * VA models and is present on TN. (I am waiting for comments with verification of this statement :))
Black color * VA does not interfere in the work at all and is associated with black (glory to our accustomed eyes :) and a good contrast ratio of 1000: 1 monitor). And the difference in black brightness is visible only in comparison (when one monitor is placed next to another).
Due to the high brightness, colors on * VA seem a little more saturated, and whites are whiter on * VA - on TN, in comparison, it appears gray.
You yourself noticed this effect when, for example, you switched the color temperature on the monitor from 6500 to 9300, when your eyes were already accustomed to a different color temperature (probably here most of the habra people climbed to change the temperature :)). But when the eyes get used again, on TN, white becomes white again :), and the other temperature is either bluer or yellower.
Colors
The colors of TN monitors and * VAs can be well calibrated (so that the grass is green, the sky is blue, and the skin colors in the photographs do not turn yellow).On TN monitors, the difference between bright and dark colors close to each other is worse (for example, bright blue with white, on the clouds, close to black (4-5%) and white (3-5%)). The differences in these colors also change depending on the viewing angle, turning into negative, or disappear. But it seems due to this on TN monitors, black is really black.
The * VA shows the full spectrum of colors - on a good video card and settings, all color gradients from 1 to 254 are visible, regardless of the viewing angle.
Photos looked good on both monitors and had reasonably rich colors.
Both monitors have 16.7M colors (not 16.2 like some TNs) - the gradients looked identical without color gaps.
Viewing angles
The first major difference between TN and * VA is the viewing angles of the monitors.If you look at the TN monitor directly in the center, then the top and bottom of the screen begins to distort (darken) the colors a little. This is noticeable in bright colors and dark colors - dark colors turn black and bright colors turn gray. On the left and right, the darkening from the corner is noticeably much less - which most likely pushes manufacturers to make monitors with a large diagonal widescreen :). Plus, due to this effect, some colors begin to fade into others and merge.
It is difficult to look at the TN monitor from above and especially from below - low-contrast colors are distorted, become faded, inverted and merge very strongly.
On * VA monitors, color distortion (or rather brightness) is also present. If you look at the monitor in the center at a distance of less than 40 cm, then on white color you can see small fading at the corners of the monitor (see the figure), which cover about 2-3% of the corners. Colors are not distorted. That is, if you look at the monitor from the largest tilt angle, the picture will not lose its colors, it will just be a little overexposed.
Due to the lack of distortion * VA monitors are made to rotate 90 degrees.
Viewing video on TN from the sofa is possible, but only it must be directed exactly at the viewers (vertically). With * VA, there are no problems with rotating the screen towards the viewer, the film can be viewed from almost any angle. Distortion is not significant.
Response time
The second major difference is response time. The former.Already now, overdrive systems are marching at full speed - and if earlier this played a major role, now it has faded into the background.
TN monitors in this direction are in the lead and are considered the best for gamers. Trails on them have not been seen for a long time. In the photographs - the square flying into the corner doubled.
* VA monitors look at the TN heel. After playing Team Fortress 2, W3 Dota, Fallout 3, no distortions and blurry trails (blur-effect) were noticed. Watching the video was also a success. In the photographs, the square flying into the corner has tripled.
Visually, in the test, if you look closely, the running square on the * VA matrix had only 1.1 times the loop.
Which one would I choose?
If you are trying to choose between S-IPS or * VA matrices and do not know what to choose, then I recommend * VA, which you will be very happy with. * VA is great for working with color - pay twice as much for the name of the matrix and the large viewing angles of S-IPS, compared to * VA is not worth it - the difference in quality is not worth the money.For games, office / Internet affairs, viewing photos, basic editing of pictures, photos and videos, and watching movies alone - TN is perfect. Even with the necessary skill + specific SuperBright (Video) modes, you can watch movies on TN on the sofa with insignificant, imperceptible color distortions (well, why would they be for a movie :)).
For processing photos, working with color in video (you can also mount it on TN in the right places, huh?), Drawing on a tablet, * VA is better suited. As a bonus, you can perfectly watch movies on it, lounging in an armchair (high brightness to help). And playing and doing Internet / office affairs on it is just as convenient as on TN.
P.s. After buying * VA, I immediately noticed on the "Welcome screen" in Windows XP on the bottom left of the purple gradient :), which I did not notice on old TN.
Before the mass distribution of smartphones, when buying phones, we evaluated them mainly by design and only occasionally paid attention to functionality. Times have changed: now all smartphones have approximately the same capabilities, and when looking only at the front panel, one gadget can hardly be distinguished from another. The technical specifications of the devices have come to the fore, and the most important among them for many is the screen. We will tell you what lies behind the terms TFT, TN, IPS, PLS, and help you choose a smartphone with the required screen characteristics.
Matrix types
In modern smartphones, three technologies are mainly used for the production of matrices: two are based on liquid crystals - TN + film and IPS, and the third - AMOLED - on organic light-emitting diodes. But before you start, it's worth talking about the abbreviation TFT, which is the source of many misconceptions. TFT (thin-film transistor) are thin-film transistors that are used to control the operation of each subpixel of modern screens. TFT technology is used in all the types of screens listed above, including AMOLED, therefore, if somewhere it is said about comparing TFT and IPS, then this is fundamentally the wrong statement of the question.
Most TFT arrays use amorphous silicon, but recently polycrystalline silicon TFT (LTPS-TFT) has been introduced into the industry. The main advantages of the new technology are the reduction in power consumption and the size of transistors, which allows achieving high pixel densities (over 500 ppi). One of the first smartphones with IPS-display and LTPS-TFT matrix was OnePlus One.
OnePlus One Smartphone
Now that we have dealt with TFT, let's go directly to the types of matrices. Despite the wide variety of LCD types, they all have the same basic principle of operation: the current applied to the liquid crystal molecules sets the polarization angle of the light (it affects the brightness of the subpixel). The polarized light is then passed through a light filter and tinted with the color of the corresponding subpixel. The first in smartphones appeared the simplest and cheapest TN + film matrices, the name of which is often abbreviated to TN. They have small viewing angles (no more than 60 degrees with a deviation from the vertical), and even with slight tilts, the image on screens with such matrices is inverted. Other disadvantages of TN-matrices are low contrast and low color accuracy. Today, such screens are used only in the cheapest smartphones, and the vast majority of new gadgets have more advanced displays.
The most widespread technology in mobile gadgets now is IPS technology, sometimes referred to as SFT. IPS-matrices appeared 20 years ago and since then have been produced in various modifications, the number of which is approaching two dozen. Nevertheless, among them it is worth highlighting those that are the most technologically advanced and are actively used at the moment: AH-IPS from LG and PLS from Samsung, which are very close in their properties, which was even a reason for litigation between manufacturers ... Modern IPS modifications have wide viewing angles that are close to 180 degrees, realistic color reproduction and provide the ability to create displays with high pixel density. Unfortunately, gadget manufacturers almost never report the exact type of IPS matrices, although when using a smartphone, the differences will be visible to the naked eye. Cheaper IPS-matrices are characterized by fading of the picture when the screen is tilted, as well as low color accuracy: the image can be either too “acidic” or, on the contrary, “faded”.
As for power consumption, in liquid crystal displays it is mainly determined by the power of the backlighting elements (smartphones use LEDs for these purposes), so the consumption of TN + film and IPS matrices can be considered approximately the same with the same brightness level.
Matrices based on organic light emitting diodes (OLEDs) are completely different from LCDs. In them, the light source is the subpixels themselves, which are ultra-miniature organic light-emitting diodes. Since there is no need for external illumination, such screens can be made thinner than LCD. Smartphones use a kind of OLED technology - AMOLED, which uses an active TFT matrix to drive subpixels. This is what allows AMOLEDs to display colors, whereas conventional OLED panels can only be monochrome. AMOLED-matrices provide the deepest blacks, since it is only necessary to completely turn off the LEDs to "display" it. Compared to LCD, such matrices have lower power consumption, especially when using dark themes, in which the black areas of the screen do not consume power at all. Another characteristic feature of AMOLED is too saturated colors. At the dawn of their appearance, such matrices really had an incredible color reproduction, and although such "childhood sores" are long in the past, still most smartphones with such screens have a built-in saturation setting, which allows the image on AMOLED to be closer to IPS-screens in perception.
Another limitation of AMOLED screens used to be the uneven lifespan of LEDs of different colors. After a couple of years of using the smartphone, this could lead to burnout of subpixels and an afterimage of some interface elements, primarily in the notification panel. But, as in the case of color reproduction, this problem is a thing of the past long ago, and modern organic LEDs are designed for at least three years of continuous operation.
Let's briefly summarize. The highest quality and brightest image at the moment is provided by AMOLED matrices: even Apple, according to rumors, will use such displays in one of the next iPhones. But, it should be borne in mind that Samsung, as the main manufacturer of such panels, keeps all the latest developments for itself, and sells "last year" matrices to other manufacturers. Therefore, when choosing a smartphone not from Samsung, you should look towards high-quality IPS-screens. But gadgets with TN + film displays are by no means worth choosing - today this technology is already considered outdated.
The perception of the image on the screen can be influenced not only by the matrix technology, but also by the pattern of subpixels. However, with LCD everything is quite simple: in them, each RGB-pixel consists of three elongated subpixels, which, depending on the technology modification, can have the shape of a rectangle or a "tick".
Things get more interesting in AMOLED screens. Since in such matrices the light sources are the subpixels themselves, and the human eye is more sensitive to pure green light than to pure red or blue, using the same pattern in AMOLED as in IPS would degrade color rendering and make the picture unrealistic. An attempt to solve this problem was the first version of PenTile technology, in which two types of pixels were used: RG (red-green) and BG (blue-green), consisting of two subpixels of the corresponding colors. Moreover, if the red and blue subpixels had a shape close to squares, then the green ones were more reminiscent of strongly elongated rectangles. The disadvantages of this pattern were "dirty" white color, jagged edges at the junction of different colors, and at low ppi - a clearly visible mesh of the substrate of subpixels, appearing due to too large a distance between them. In addition, the resolution indicated in the characteristics of such devices was "dishonest": if the IPS HD matrix has 2,764,800 subpixels, then the AMOLED HD matrix is only 1,843,200, which led to a difference in the definition of IPS and AMOLED matrices visible to the naked eye with, seemingly the same pixel density. The last flagship smartphone with such an AMOLED matrix was the Samsung Galaxy S III.
In the Galaxy Note II smartpad, the South Korean company made an attempt to abandon PenTile: the device's screen had full RBG pixels, albeit with an unusual arrangement of subpixels. Nevertheless, for unclear reasons, in the future Samsung refused such a pattern - perhaps the manufacturer faced the problem of further increasing the ppi.
In its modern screens, Samsung has reverted to RG-BG pixels using a new type of pattern called the Diamond PenTile. The new technology made it possible to make the white color more natural, and as for the jagged edges (for example, individual red subpixels were clearly visible around a white object on a black background), this problem was solved even easier - increasing the ppi to such an extent that the irregularities were no longer noticeable ... Diamond PenTile is used in all Samsung flagships starting with the Galaxy S4 model.
At the end of this section, it is worth mentioning one more picture of AMOLED matrices - PenTile RGBW, which is obtained by adding a fourth, white, to the three main subpixels. Before the advent of Diamond PenTile, such a pattern was the only recipe for pure white, but it never became widespread - one of the last mobile gadgets with PenTile RGBW was the Galaxy Note 10.1 2014 tablet. Now AMOLED matrices with RGBW pixels are used in TVs, since they do not require high ppi. For the sake of fairness, we also mention that RGBW pixels can be used in LCDs, but we are not aware of examples of using such matrices in smartphones.
Unlike AMOLED, high-quality IPS-matrices have never experienced quality problems associated with the subpixel pattern. However, the Diamond PenTile technology, together with the high pixel density, has allowed AMOLED to catch up and overtake IPS. Therefore, if you are picky about gadgets, you should not buy a smartphone with an AMOLED screen, which has a pixel density of less than 300 ppi. At a higher density, no defects will be noticeable.
Design features
The variety of displays on modern mobile gadgets does not end with imaging technologies alone. One of the first things that manufacturers took on was the air gap between the projected capacitive sensor and the display itself. This is how the OGS technology appeared, combining the sensor and the matrix into one glass bag in the form of a sandwich. This gave a significant leap in image quality: the maximum brightness and viewing angles increased, the color reproduction was improved. Of course, the thickness of the entire package has also been reduced, allowing for thinner smartphones. Alas, the technology also has drawbacks: now, if you break the glass, changing it separately from the display is almost impossible. But the advantages in quality still turned out to be more important and now non-OGS screens can be found only in the cheapest devices.
Recently, experiments with the shape of glass have also become popular. And they began not recently, but at least in 2011: HTC Sensation had a glass concave in the center, which, according to the manufacturer, was supposed to protect the screen from scratches. But such glasses reached a qualitatively new level with the advent of "2.5D screens" with curved glass at the edges, which creates the feeling of an "endless" screen and makes the edges of smartphones smoother. Such glasses are actively used by Apple in their gadgets, and recently they have become more and more popular.
A logical step in the same direction was the bending of not only glass, but also the display itself, which became possible when using polymer substrates instead of glass. Here the palm, of course, belongs to Samsung with its Galaxy Note Edge smartphone, in which one of the side edges of the screen was curved.
Another method was proposed by LG, which managed to bend not only the display, but the entire smartphone along its short side. However, LG G Flex and its successor did not gain popularity, after which the manufacturer refused to further release such devices.
Also, some companies are trying to improve human interaction with the screen, working on its sensory part. For example, some devices are equipped with high-sensitivity sensors that allow you to work with them even with gloves, while other screens receive an inductive substrate to support the stylus. The first technology is actively used by Samsung and Microsoft (formerly Nokia), and the second - by Samsung, Microsoft and Apple.
The future of screens
Do not think that modern displays in smartphones have reached the highest point of their development: technologies still have room to grow. One of the most promising are quantum dot displays (QLED). A quantum dot is a microscopic piece of a semiconductor in which quantum effects begin to play a significant role. Simplified, the radiation process looks like this: the effect of a weak electric current makes the electrons of the quantum dots change energy, while emitting light. The frequency of the emitted light depends on the size and material of the dots, so that almost any color in the visible range can be achieved. Scientists promise that QLED matrices will have better color reproduction, contrast, higher brightness and lower power consumption. Partially, the technology of screens on quantum dots is used in Sony TV screens, and prototypes are available from LG and Philips, but there is no talk of the massive use of such displays in TVs or smartphones.
It is highly likely that in the near future we will see in smartphones not only curved, but also completely flexible displays. Moreover, prototypes of such AMOLED matrices that are almost ready for mass production have existed for a couple of years. The limitation is the electronics of the smartphone, which is still impossible to make flexible. On the other hand, large companies can change the very concept of a smartphone by releasing something like the gadget shown in the photo below - we just have to wait, because the development of technology is happening right before our eyes.
AH-IPS technology is one of many IPS matrix developments. It is worth noting that this is the latest development that eliminated most of the disadvantages of IPS matrices, which brought LCD displays to a new level. Thanks to this, they are worthy of competing with plasma panels.
Taking into account the fact that the technology is relatively new, many users have a question, AH-IPS matrix, what is it, and what advantages does it have?
To answer these questions, you need to know what an IPS matrix is, how it works, and how monitors and TVs with such displays are arranged. This will allow you to understand what improvements have been made in the AH-IPS matrices.
1. So, what is an IPS matrix
First of all, it should be noted that the IPS-display belongs to the active type of LCD matrix. In other words, it is a kind of TFT LCD. This, in turn, means that the principle of operation is to use liquid crystal molecules that are already familiar to you. However, the IPS matrix has some structural features, which will be discussed later.
As you've probably guessed by now, IPS is an abbreviation. The full name looks like this - In - Plane Switching, which in Russian means plane switching. The technology received this name due to the fact that the liquid crystal molecules in the cells of the IPS matrix are always located in the same plane. Moreover, they are always parallel to the plane of the panel itself.
Before the advent of TFT AH-IPS matrices, IPS displays have come a long way of development and improvement. The first IPS screens were developed to address the shortcomings of TN matrices. Of course, the picture quality has been significantly improved, but the IPS displays have a long response time.
Before the advent of IPS technology in standard LCD elements, when exposed to an electric voltage on liquid crystal molecules, their orientation changed. As a result, the ability to rotate the polarization angle is lost. However, the main drawback of TN technology was that the polarization rotation was necessary.
The main distinguishing feature of the IPS technology was that both translucent control electrodes were located in the same plane - exclusively on the underside of the LCD cell. This means that all liquid crystal molecules are always located in one plane, which in turn is parallel to the plane of the screen.
This solution has significantly increased the viewing angles, which are practically not inferior to CRT monitors. At the same time, the quality of color rendering of IPS displays significantly surpassed all analogues available at that time.
In IPS displays, the liquid crystal molecules are located in the plane of the polarizing filters, and rotate in it at the required angle, depending on the voltage acting on them. This changes the angle of refraction, and, accordingly, the phase of the light radiation passing through the molecules. This structure is absolutely opposite to TN matrices. This solution made it possible to achieve more natural color reproduction, as well as an increase in contrast.
1.1. LCD type TFT AH-IPS
Since the appearance of this type of matrix in 1995, there have been constant developments and improvements. As a result, in 2011, the AH-IPS matrix appeared, which had excellent image quality, high contrast, brightness, clarity and image resolution. At the same time, the response time of such displays was reduced to 5 ms. This means that such monitors are capable of displaying the brightest and fastest special effects. Moreover, due to some features, this type of matrix is capable of displaying the most natural and saturated colors.
AH-IPS monitors have the highest image quality. Of course, their cost is also high, but if you compare them with plasma panels, then IPS-displays are more affordable, while practically not inferior in image quality. AH IPS is the latest and most expensive development in the IPS technology family. However, it eliminated most of the shortcomings of all previous versions of IPS displays. In particular, this technology made it possible to achieve the lowest response time.
Due to the wide variety of IPS matrix designs, users have a question, which is better, AH-IPS or E-IPS? It is worth noting that there are many other types of IPS displays. But if we talk about these two types, then we can say that E-IPS displays have a lower cost in comparison with AH-IPS.
The first technology was developed earlier. It has some disadvantages. As a rule, such matrices have a small diagonal size - no more than 20 ”. The peculiarities of this technology do not allow creating screens of large sizes, since otherwise, it is almost impossible to achieve high definition and image accuracy. However, with sizes no more than 20 "E-IPS displays are very high performance.
AH-IPS, in turn, is used in more expensive models of monitors and TVs. This technology allows you to create screens of large sizes, while with high resolution, image accuracy and clarity.
If we talk about which monitor to choose, then you should decide for what purposes you need it, what diagonal sizes will suit you, and also how much you expect. If we talk about quality, then here, as elsewhere and everywhere, the rule applies: the more expensive, the better. Of course, a lot depends on the manufacturer, or rather on what materials were used, as well as on the design features. Therefore, when choosing, you should carefully study the technical characteristics and clarify some questions with the seller.
It is worth noting that it is on AH-IPS matrices that manufacturers have high hopes.
2. Backlight type AH-IPS matrix
To display the image on the monitor screen, the matrix backlight is required. If we talk about old displays - the first IPS and TN matrices, then in such devices fluorescent lamps were used as a backlight, which could not provide sufficiently bright illumination and uniform light distribution. In addition, these lamps consumed a lot of electricity.
All these shortcomings were completely resolved after the development of a new type of backlighting - LED. This technology is based on the use of LEDs, which are small in size and capable of emitting bright light. Such a simple but very effective solution made it possible to achieve the most uniform light distribution by placing the LEDs on the back of the matrix. This made it possible to create large enough screen sizes without sacrificing image quality.
In addition, LEDs consume very little power and have a bright white light, which allows for even greater brightness and contrast enhancements. This, in turn, had a positive effect on the image quality. AH-IPS technology with LED backlighting is the most successful development to date, allowing you to enjoy truly high picture quality.
It should be noted that fluorescent lamps are considered obsolete and are becoming less common. Moreover, almost all new developments of matrices, in particular AH-IPS, use only LED backlighting.
3. AH-IPS (lg ips234v) VS TN: Video
If we talk about design features, then thanks to the small size of the LEDs, it became possible to create the thinnest monitors. Another advantage of LEDs is their blinking frequency. Their flickering frequency is so high that it cannot be seen with the naked eye. Moreover, it is a known fact that even a frequency of 100 Hz, although not visible, still has a negative effect on the organs of vision, as well as on the human psyche.
The screen flicker frequency of 100 Hz and below causes a feeling of fatigue in the organs of vision, as well as a depressed state. Of course, this is felt when working for a long time in front of the monitor or when watching movies. The blinking frequency of the LED is several times higher than the critical mark of 100 Hz, which makes working with such monitors as comfortable as possible. And even with prolonged viewing of films, such screens do not have any negative impact on a person.
This is one of the reasons why TV and monitor manufacturers prefer LED backlighting.
4. Advantages of AH-IPS matrices
As mentioned above, this type of matrix was the last to be developed. This means that the most innovative solutions and achievements were used to develop this technology. Thus, the AH-IPS LCD is a solution to all the shortcomings inherent in all previous IPS matrices. But let's take a closer look at the benefits:
- High screen resolution. The AH-IPS monitor matrix type has the highest screen resolution. This means that such monitors display the clearest and most accurate image. Moreover, modern technology has made it possible to achieve the highest pixel density per inch of the screen. This, in turn, directly affects the clarity and accuracy of the displayed image.
- The maximum number of colors and shades. Another advantage of this type of display is the highest color quality. Monitors with such a matrix display the greatest number of colors and shades, which makes the image colors as natural and natural as possible. This feature is appreciated by professional photo and image editors.
- Viewing angles. AH-IPS matrices have the largest viewing angles that can only be compared with a plasma panel. Therefore, such displays are the strongest competitors for plasma TVs.
- High brightness and contrast. The peculiarities of the technology made it possible to increase the brightness and contrast of the screen to the limit, which had a positive effect on the image quality. The unique design and modern technologies have made it possible to achieve the most uniform distribution of light across the entire surface of the display, both in black and white. It also significantly improved image quality.
- Fast response. If the first IPS matrices had a drawback, which was a slow response, because of which such monitors were inferior to TN matrices, then modern AH-IPS LCD matrices are completely devoid of such a drawback. What's more, they outperform even today's TN + Film matrices, making them an excellent choice for any application.
It should be understood that the characteristics of the AH-IPS matrix also depend on the manufacturer. Not all displays made using this technology have the same high performance. It all depends on the materials used, as well as on some features in the design of the display. The cost of the product also depends on this. So, the higher-quality materials and components were used to make an AH-IPS display, the higher image quality the monitor will have, and, accordingly, the more expensive the device will be.
To date, little is known about the real characteristics of AH-IPS matrices. However, one thing is for sure - this type of display is significantly superior to all previous models. Of course, it can be compared with other types of IPS matrices, but it should be borne in mind that, as mentioned above, not all monitors with the same matrix have the same performance. The matrix itself has tremendous prospects. In the near future, it will be encountered much more often. In addition, technologies do not stand still, active developments are constantly underway to improve image quality, as well as improve response.
IPS or TFT - which is better to choose? More recently, I was faced with the need to give a person a reasoned answer to this question when buying a tablet. Unambiguously knowing what was already heard by everyone, I was ready to immediately give an answer. But nevertheless, I decided to work out this topic a little in order to support what was said with compelling reasons. I had to shovel a little information 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 making the final decision as to which is still better - IPS or TFT matrix. Even if you need to buy a new tablet or smartphone, the information below will also prove to be relevant and useful. So, let's start our small overview.
A little about the technologies used for the production of IPS-screens
Although most modern displays are liquid crystal, slightly different technologies can be used in each case, resulting in differences in the characteristics of the final product. The terminology used throughout may vary. Therefore, in order not to be misled about TFT or IPS monitors, the following should be noted.
First and foremost, separating the weeds from the chaff: IPS technology is nothing different from TFT. It is TFT - more precisely, 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. As for the technologies used:
- TFT (we understand that we are talking about TFT-TN). Liquid crystal display (thin film transistors). Crystals are located in the matrix body spirally between two plates. Image formation occurs due to the rotation of the crystal molecules. If there is no voltage, their horizontal rotation angle is 90 degrees, while they are white. 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). Those same crystals, only their arrangement is parallel to each other. When there is no tension, 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 primarily determined by the image display quality. In turn, quality can be decomposed into indicators such as contrast and viewing angle.
When it comes to the IPS matrix, it significantly outperforms the 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 color distortions in the image.
An important factor influencing the choice of the screen of 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 either side, the IPS matrix undoubtedly wins, allowing several friends or colleagues to enjoy the image without distortion. This is also important to consider when buying a particular device.
IPS and TFT display response speed
The apparent advantage of a TFT display over an IPS screen is its high response speed. He has no competitors here. At the same time, it takes more time for the IPS matrix to rotate the array of crystals that are located in parallel.
This fact leads to the obvious conclusion that it is better to use TFT in devices whose purpose is critical to the display speed. On the other hand, when it comes to an ordinary purpose (as a tool for study, communication via the Internet and other tasks), this difference is almost imperceptible 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, which we continue to list. How is the energy of the accumulators of screens made according to different technologies consumed? There are obvious differences. The power consumption of IPS is really higher. Not only more time, but also more voltage is needed to rotate the crystals of this type of matrix. The logical conclusion is the increased load on the battery. Therefore, when buying used devices, when it is obvious that the battery is no longer new, this fact must be carefully weighed. If you buy a new phone, tablet or smartphone, and at the same time, its use involves a long stay out of reach from the mains, it is better to focus on high-quality TFT matrices.
The cost of devices with different types of displays
The cost of IPS screens is 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 equipment to only make a call, what's the point of overpaying for a screen that won't take advantage of it? Moreover, if it increases the overall power consumption of a smartphone or tablet.
TFT or IPS - which is better? Which matrix should you choose?
So, if you need a modern high-quality tablet that you can not only work with, but also comfortably show high-quality photos to your friends, definitely choose only devices with an IPS matrix. Paying attention to the manufacturers' markings, do not forget that TFT includes both TN and IPS matrices. But this is far from all of their types. Knowing which is the best of these two types of matrices - TFT or IPS, and wanting to buy a tablet, smartphone or phone, contact any of the trusted online stores (Rozetka, Eldorado, Citrus and others), which provide a full range of these products, with the ability to filter by the most significant parameters.
By the way, the person who bought the tablet with the 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.
For many, liquid crystal displays (LCDs) are associated primarily with flat panel monitors, "cool" TVs, laptops, camcorders and cell phones. Some will add here PDA, electronic games, ATMs. But there are still many areas where displays with high brightness, rugged construction, and a wide temperature range are required.
Flat panel displays are used where minimum power consumption, weight and dimensions are critical parameters. Mechanical engineering, automotive, railways, offshore drilling rigs, mining equipment, outdoor retail outlets, aviation electronics, marine, special vehicles, security systems, medical equipment, weapons - this is not a complete list of applications for LCD displays.
The constant development of technologies in this area has made it possible to reduce the cost of LCD production to such a level that a qualitative transition has taken place: expensive exotic has become commonplace. Ease of use has also become an important factor in the rapid adoption of LCDs in industry.
This article discusses the basic parameters of various types of 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).
All the 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 the production of LCDs (Fig. 1): passive matrix (PMLCD-STN) and active matrix (AMLCD).
MIM-LCD and Diode-LCD technologies have not become widespread 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 with a passive matrix, TFT LCD has a higher contrast, saturation, shorter switching time (no "tails" in moving objects).
The brightness control in the liquid crystal display is based on the polarization of light (general physics course): light is polarized by passing through a polarizing filter (with a specific polarization angle). In this case, the observer sees only a decrease in the brightness of the light (almost 2 times). If you put another such filter behind this filter, then the light will be completely absorbed (the polarization angle of the second filter is perpendicular to the polarization angle of the first one) or completely pass (the polarization angles coincide). With a smooth change in the polarization angle of the second filter, the intensity of the transmitted light will also change smoothly.
The principle of operation and the "sandwich" structure of all TFT LCDs is approximately the same (Fig. 2). Light from a backlight lamp (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. After passing through such a structure, the light changes its polarization and will be either completely absorbed by the second polarizing filter (black screen), or will not be absorbed (white), or the absorption will be partial (spectrum colors). The color of the image is determined by color filters (similar to cathode-ray tubes, each pixel of the matrix consists of three subpixels - red, green and cyan).
Rice. 2. Structure of TFT LCD
Pixel TFT
Color filters for red, green and blue are integrated into the glass base and are located close to each other. It can be a vertical stripe, a mosaic structure, or a 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 subpixels) for a 15.1 "TFT LCD (1024 x 768 dots) is approximately 0.30 mm, and for 18.1" (1280 x 1024 dots) it is 0.28 mm. TFT LCDs are physically limited by the maximum screen area. Don't expect 1280 x 1024 resolution at 15 "diagonal and 0.297 mm dot pitch.
Rice. 3. Color filter structure
At close range, the points are clearly distinguishable, but this is not a problem: when forming a 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 display with a pitch between subpixels of 0.1 mm, the angle of view will be 0.014 ° (the color of each subpixel can only be distinguished by a person with eagle vision).
LCD types
TN (Twist Nematic) TFT or TN + Film TFT is the first technology to appear on the LCD market, the main advantage of which is its low cost. Disadvantages: black is more like dark gray, which leads to low image contrast, "dead" pixels (if 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 expanded to 170 °, other functions are the same as in TN + Film (response time is about 25ms), almost perfect black color. Advantages: good contrast, "dead" pixel - black.
Super IPS (Hitachi), Advansed SFT (manufacturer - NEC). Advantages: bright contrasting image, color distortions are almost invisible, viewing angles are increased (up to 170 ° vertically and horizontally) and exceptional clarity is provided.
UA-IPS (Ultra Advanced IPS), UA-SFT (Ultra Advanced SFT) (NEC). The response time is sufficient to ensure minimal color distortion when viewing the screen from different angles, increased panel transparency and expanded color gamut at a sufficiently high brightness level.
MVA (Multi-Domain Vertical Alignment) (Fujitsu) The main advantage is the shortest response time and high contrast. The main disadvantage is the high cost.
PVA (Patterned Vertical Alignment) (Samsung). Microstructural vertical placement of LCDs.
Design
The design of the liquid crystal display is determined by the arrangement of the layers in the "sandwich" (including the light-conducting layer) and is of the greatest importance for the quality of the image on the screen (in any conditions: from a dark room to working in sunlight). There are three main types of color LCDs in use today:
- transmissive, intended mainly for indoor equipment;
- reflective is used in calculators and watches;
- projection is used in LCD projectors.
A compromise type of transmissive display type for both indoor and outdoor use is the transflective design.
Transmissive display type... In this type of design, light enters through the LCD panel from the back (backlight) (Figure 4). This technology is used in most LCDs used in laptops and PDAs. Transmissive LCD has high image quality indoors and low (black screen) in sunlight. the sun's rays reflected from the surface of the screen completely suppress the light emitted by the backlight. This problem is (currently) solved in two ways: increasing the brightness of the backlight and decreasing the amount of reflected sunlight.
Rice. 4. Construction of transmissive type liquid crystal display
To work in daylight in the shade, a backlight is required that provides 500 cd / m2, in direct sunlight - 1000 cd / m2. A brightness of 300 cd / m2 can be achieved by increasing the brightness of one CCFL (Cold Cathode Fluorescent Lamp) lamp to the maximum or by adding a second lamp opposite. High brightness LCD models use 8 to 16 lamps. However, increasing the brightness of the backlight increases the drain on the battery (a single backlight consumes about 30% of the power used by the device). Therefore, screens with increased brightness can only be used with an external power supply.
Reducing the amount of reflected light is achieved by applying an antireflection coating to one or more layers of the display, replacing the standard polarizing layer with a minimally reflective layer, adding films that increase brightness and, thus, increase the efficiency of the light source. Fujitsu LCDs fill the converter with a liquid with a refractive index equal to the refractive index of the touch panel, which significantly 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 used indoors, it works in a similar way to a transmissive LCD, in which some of the light is absorbed by the reflective layer. In daylight, sunlight reflects off the mirror layer and illuminates the LC layer, while the light passes the liquid crystals twice (inward and then outward). As a consequence, the picture quality in daylight is lower than in artificial lighting indoors, when the light passes through the LCD once.
Rice. 5. Construction of semi-transparent type liquid crystal display
The balance between indoor and daylight image quality is achieved by matching the characteristics of the transmissive and reflective layers.
Reflective display type(reflective) has a fully reflective specular layer. All lighting (sunlight or front light) (Figure 6) passes through the LCD, reflects off the mirror layer, and then passes through the LCD again. In this case, the image quality of reflective type displays is lower than that of semi-transmissive ones (since in both cases similar technologies are used). Indoors, front lighting is not as effective as back lighting, and therefore the picture quality is lower.
Rice. 6. Design of reflective type liquid crystal display
Basic parameters of liquid crystal panels
Permission. A digital panel, the number of pixels in which strictly corresponds to the nominal resolution, must correctly and quickly scale the image. An easy way to check the quality of scaling is to change the resolution (small print on screen). It is easy to see the quality of the interpolation from the contours of the letters. A high-quality algorithm produces even, but slightly blurry letters, while fast integer interpolation is bound to introduce distortion. Speed is the second resolution parameter (it takes time to interpolate to scale one frame).
Dead pixels. Several pixels may not work on a flat panel (they are always the same color), which appear during the production process and cannot be restored.
The ISO 13406-2 standard defines the limit values for the number of defective pixels per million. According to the table, LCD panels are divided into 4 classes.
Table 1
Type 1 - permanently 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 at which the image contrast decreases by 10 times. But first of all, when changing the viewing angle from 90 (color distortions are visible. Therefore, the larger the viewing angle, the better. There are horizontal and vertical viewing angles, the recommended minimum values are 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 the liquid crystal molecules (the less, the better). For fast moving objects not to 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). The response time (more precisely, the shutdown time as the longest time during which an individual pixel changes its brightness to the maximum) determines the refresh rate of the image on the screen
FPS = 1 s / response time.
Brightness- the advantage of the LCD display, which is, on average, two times higher than the CRT indicators: 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 getting a black point, since the backlight is always on and the polarization effect is used to produce dark tones. The black color depends on the quality of the blocking of the luminous flux of the backlight.
LCDs as sensors. The decrease in cost and the appearance 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, directly to the serial port (COM1 - COM4) (Fig. 7). For control, decoding of signals and suppression of "bouncing" (if you can call the definition of touch), a PIC controller (for example, IF190 from Data Display) is used, which provides high speed and accuracy in determining the touch point.
Rice. 7. Block diagram of TFT LCD on the example of NL6448BC-26-01 display from NEC
We will complete the theoretical research on this and move on to the realities of today, or rather, to what is now available on the market of liquid crystal displays. Among all TFT LCD manufacturers, consider products from NEC, Sharp, Siemens and Samsung. The choice of these firms is due to
- market leadership in LCD displays and TFT LCD manufacturing technologies;
- availability of products on the market of the CIS countries.
NEC Corporation has been producing liquid crystal displays (20% of the market) since their inception and offers not only a wide selection, but also various options: Standard, Special and Specific. The standard option is computers, office equipment, home electronics, communications systems, etc. A special version is used in transport (any: land and sea), traffic control systems, security systems, medical equipment (not related to life support systems). For weapons systems, aviation, space equipment, control systems for nuclear reactors, life support systems, and others similar, a special version is intended (it is clear that it is not cheap).
The list of manufactured LCD panels for industrial use (inverter for the backlight lamp is supplied separately) is shown in Table 2, and the block diagram (using the example of a 10-inch display NL6448BC26-01) is shown in Fig. eight.
Rice. 8. Display appearance
Table 2. NEC LCD Panel Models
| 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 | No 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 | Dedicated NTSC / PAL RGB input, built-in inverter, slim |
| NL3224AC35-10 | 5,5 | 320x240 | Full color | Dedicated NTSC / PAL RGB input, built-in inverter |
| NL3224AC35-13 | 5,5 | 320x240 | Full color | Dedicated 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 clock was manufactured using TN LCD technology. In the second half of the 70s, the transition from eight-segment liquid crystal displays to the production of matrices with addressing of each point began. In 1976, Sharp released a 5.5-inch black-and-white TV based on a 160x120-pixel LCD matrix. A short list of products is in table 3.
Table 3. Sharp LCD Panel Models
Produces liquid crystal displays with an active matrix on low-temperature polysilicon thin-film transistors. Key specifications for 10.5 "and 15" displays are shown in Table 4. Pay attention to operating temperature range and shock resistance.
Table 4. Main characteristics of Siemens LCD displays
Notes:
I - built-in inverter l - according to MIL-STD810 standard
The firm produces liquid crystal displays under the brand name "Wiseview ™". Starting with 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 to medium-sized TFT LCD segment, with some models designed to work in natural light ( table 5).
Table 5. Key Features of Samsung Small and Medium LCDs
Notes:
LED - LED; CCFL - cold cathode fluorescent lamp;
The displays use PVA technology.
Conclusions.
Currently, the choice of a liquid crystal display model is determined by the requirements of a particular application and, to a much lesser extent, by the cost of the LCD.
