Simple devices that are equipped with this type of equipment can work either with a black and white image or with 2-5 colors. At the moment, the described screens are used to display graphic or text information. They are installed in computers, laptops, TVs, phones, cameras, tablets. Most electronic devices currently work with just such a screen. One of the popular varieties of such technology is an active matrix liquid crystal display.
Story
Liquid crystals were first discovered in 1888. This was done by the Austrian Reinitzer. In 1927, Russian physicist Fredericks discovered the transition, which was named after him. Currently, it is widely used in the creation of liquid crystal displays. In 1970, RCA introduced the first screen of this type. It was immediately used in watches, calculators and other devices.
A little later, a matrix display was created that worked with black and white images. The color LCD screen appeared in 1987. Its creator is the Sharp company. The diagonal of this device was 3 inches. Reviews for this type of LCD screen have been positive.
Device
When considering LCD screens, it is necessary to mention the design of the technology.
This device consists of an LCD matrix and light sources that directly provide the backlight itself. There is a plastic case framed by a metal frame. It is necessary to give rigidity. Contact harnesses, which are wires, are also used.
LCD pixels consist of two transparent type electrodes. A layer of molecules is placed between them, and there are also two polarizing filters. Their planes are perpendicular. One point should be noted. It lies in the fact that if liquid crystals did not exist between the above filters, then the light passing through one of them would be immediately blocked by the second.
The surface of the electrodes that comes into contact with liquid crystals is covered with a special shell. Due to this, the molecules move in one direction. As mentioned above, they are mainly located perpendicularly. In the absence of tension, all molecules have a screw structure. Due to this, the light is refracted and passes through the second filter without loss. Now anyone should understand that this is an LCD from a physics point of view.
Advantages
When compared with cathode ray devices, the liquid crystal display wins here. It is small in size and weight. LCD devices do not flicker, they have no problems with focusing, as well as with convergence of beams, there is no interference that arises from magnetic fields, there are no problems with the geometry of the picture and its clarity. You can mount the LCD display on brackets to the wall. It's very easy to do. In this case, the picture will not lose its qualities.
How much an LCD monitor consumes depends entirely on the image settings, the model of the device itself, as well as the signal supply characteristics. Therefore, this figure can either coincide with the consumption of the same beam devices and plasma screens, or be much lower. At the moment, it is known that the energy consumption of LCD monitors will be determined by the power of the installed lamps that provide the backlight.
It is also necessary to say something about small-sized LCD displays. What is it, how are they different? Most of these devices do not have backlighting. These screens are used in calculators and watches. Such devices have completely low power consumption, so they can operate autonomously for up to several years.
Flaws
However, these devices also have disadvantages. Unfortunately, many shortcomings are difficult to eliminate.
When compared with electron beam technology, a clear image on an LCD display can only be obtained at standard resolution. To achieve good characterization of other pictures, you will have to use interpolation.
LCD monitors have average contrast as well as poor black depth. If you want to increase the first indicator, then you need to increase the brightness, which does not always provide comfortable viewing. This problem is noticeable in LCD devices from Sony.
The frame rate of LCD displays is much slower when compared to plasma screens or cathode beam screens. At the moment, Overdrive technology has been developed, but it does not solve the speed problem.
There are also some nuances with viewing angles. They are completely dependent on contrast. Electron beam technology does not have this problem. LCD monitors are not protected from mechanical damage; the matrix is not covered with glass, so pressing hard can deform the crystals.
Backlight
Explaining what it is - LCD, we should also talk about this characteristic. The crystals themselves do not glow. Therefore, in order for the image to become visible, it is necessary to have a light source. It can be external or internal.
The first should be the sun's rays. In the second option, an artificial source is used.
As a rule, lamps with built-in illumination are installed behind all layers of liquid crystals, due to which they are visible through. There is also side lighting, which is used in watches. In LCD TVs (what is this - the answer above) this type of design is not used.
As for ambient lighting, as a rule, black and white displays on watches and mobile phones work when such a source is present. Behind the pixel layer is a special matte reflective surface. It allows you to reflect sunlight or radiation from lamps. Thanks to this, you can use such devices in the dark, as manufacturers build in side lighting.
Additional information
There are displays that combine an external source and additional built-in lamps. Previously, some watches that had a monochrome LCD screen used a special small incandescent lamp. However, due to the fact that it consumes too much energy, this solution is not profitable. Such devices are no longer used in televisions, as they generate a large amount of heat. Because of this, liquid crystals are destroyed and burn out.
At the beginning of 2010, LCD TVs became widespread (we discussed what they are above), which had such displays that should not be confused with truly real LED screens, where each pixel glows independently, being an LED.
Describing the differences between IPS and TN matrices as part of advice when buying a monitor or laptop. It's time to talk about all the modern display production technologies that we may encounter and have an idea about types of matrices in devices of our generation. Do not confuse with LED, EDGE LED, Direct LED - these are types of screen backlighting and display technologies are indirectly related.
Probably everyone can remember the monitor with a cathode ray tube that they used before. True, there are still users and fans of CRT technology. Currently, screens have increased in diagonal size, display manufacturing technologies have changed, and there are more and more varieties in the characteristics of matrices, denoted by the abbreviations TN, TN-Film, IPS, Amoled, etc.
The information in this article will help you choose a monitor, smartphone, tablet and other various types of equipment. In addition, it will highlight the technologies for creating displays, as well as the types and features of their matrices.
A few words about liquid crystal displays
LCD (Liquid Crystal Display) is a display made from liquid crystals that change their location when voltage is applied to them. If you come close to such a display and look closely at it, you will notice that it consists of small dots - pixels (liquid crystals). In turn, each pixel consists of red, blue and green subpixels. When voltage is applied, the subpixels are arranged in a certain order and transmit light through them, thus forming a pixel of a certain color. Many such pixels form an image on the screen of a monitor or other device.
The first mass-produced monitors were equipped matrices TN- having the simplest design, but which cannot be called the highest quality type of matrix. Although among this type of matrices there are very high-quality specimens. This technology is based on the fact that in the absence of voltage, subpixels transmit light through themselves, forming a white dot on the screen. When voltage is applied to the subpixels, they are arranged in a certain order, forming a pixel of a given color.
Disadvantages of TN matrix
- Due to the fact that the standard pixel color, in the absence of voltage, is white, this type of matrix does not have the best color rendering. Colors appear duller and faded, and blacks appear more of a dark gray.
- Another main disadvantage of a TN matrix is small viewing angles. Partially they tried to cope with this problem by improving TN technology to TN+Film, using an additional layer applied to the screen. Viewing angles became larger, but still remained far from ideal.
At the moment, TN+Film matrices have completely replaced TN.
Advantages of TN matrix
- fast response time
- relatively inexpensive cost.
Drawing conclusions, we can say that if you need an inexpensive monitor for office work or surfing the Internet, monitors with TN+Film matrices are best suited.
The main difference between IPS matrix technology and TN— perpendicular arrangement of subpixels in the absence of voltage, which form a black point. That is, in a state of calm the screen remains black.
Advantages of IPS matrices
- better color reproduction compared to screens with TN matrices: you have bright and rich colors on the screen, and black remains truly black. Accordingly, when voltage is applied, the pixels change color. Considering this feature, owners of smartphones and tablets with IPS screens can be advised to use dark color schemes and wallpapers on the desktop, then the smartphone’s battery life will last a little longer.
- large viewing angles. On most screens they are 178°. For monitors, and especially for mobile devices (smartphones and tablets), this feature is important when the user chooses a gadget.
Disadvantages of IPS matrices
- long screen response time. This affects the display in dynamic pictures such as games and movies. In modern IPS panels, things are better with response time.
- higher cost compared to TN.
To summarize, it is better to choose phones and tablets with IPS matrices, and then the user will receive great aesthetic pleasure from using the device. The matrix for a monitor is not so critical, modern ones.
AMOLED screens
The latest smartphone models are equipped with AMOLED displays. This technology for creating matrices is based on active LEDs, which begin to glow and display color when voltage is applied to them.
let's consider features of Amoled matrices:
- Color rendition. The saturation and contrast of such screens are higher than required. The colors are displayed so brightly that some users may experience eye strain when using their smartphone for long periods of time. But the black color is displayed even blacker than even in IPS matrices.
- Display power consumption. Just like IPS, displaying black requires less power than displaying a specific color, much less white. But the difference in power consumption between displaying black and white in AMOLED screens is much greater. Displaying white requires several times more energy than displaying black.
- "Picture Memory". If a static image is displayed for a long time, marks may remain on the screen, and this in turn affects the quality of the information displayed.
Also, due to their rather high cost, AMOLED screens are currently only used in smartphones. Monitors built on this technology are unreasonably expensive.
VA (Vertical Alignment)- this technology, developed by Fujitsu, can be considered as a compromise between TN and IPS matrices. In VA matrices, the crystals in the off state are located perpendicular to the screen plane. Accordingly, the black color is ensured as pure and deep as possible, but when the matrix is rotated relative to the direction of view, the crystals will not be visible equally. To solve the problem, a multi-domain structure is used. Technology Multi-Domain Vertical Alignment (MVA) provides protrusions on the plates that determine the direction of rotation of the crystals. If two subdomains rotate in opposite directions, then when viewed from the side, one of them will be darker and the other lighter, so for the human eye the deviations cancel out. There are no protrusions in PVA dies developed by Samsung, and the crystals are strictly vertical when turned off. In order for the crystals of neighboring subdomains to rotate in opposite directions, the lower electrodes are shifted relative to the upper ones.
To reduce response time, Premium MVA and S-PVA matrices use a dynamic voltage increase system for individual sections of the matrix, which is usually called Overdrive. The color rendition of PMVA and SPVA matrices is almost as good as that of IPS, the response time is slightly inferior to TN, the viewing angles are as wide as possible, the black color is the best, the brightness and contrast are the highest possible among all existing technologies. However, even with a slight deviation of the direction of view from the perpendicular, even by 5–10 degrees, distortions in halftones can be noticed. This will go unnoticed by most, but professional photographers continue to dislike VA technology for this.
MVA and PVA matrices have excellent contrast and viewing angles, but the situation with response time is worse - it grows as the difference between the final and initial states of the pixel decreases. Early models of such monitors were almost unsuitable for dynamic games, but now they show results close to TN matrices. Color rendering *VA matrices, of course, is inferior to IPS matrices, but remains at a high level. However, due to their high contrast, these monitors are an excellent choice for working with text and photography, with drawing graphics, and also as home monitors.
In conclusion, I can say that the choice is always yours...
LCD displays have taken over homes and offices, so it's no surprise that when you're shopping for a brand new TV, you're choosing between LCD and... LCD, LCD and LED. Some will advise taking LCD as a more affordable option, others will recommend LED as a more advanced technology. But you shouldn’t be guided only by this: first, be curious about the difference between an LCD and an LED TV.
In fact
The difference between LCD and LED TVs is the backlight method. Firstly, it is luminescent or fluorescent, and secondly, it is LED. In turn, LEDs can be located entirely at the back or only on the sides of the LCD panel, which affects the quality of image transmission and the price of the device. The LED matrix can be formed from diodes of one or three colors (RGB).
Technically, this is the main difference between an LCD and an LED TV. And this is not a fundamentally new technology, but just a different approach to lighting. However, do not forget: no lighting - no image (the crystal itself does not glow), good lighting - high-quality picture. Therefore, conventional and LED LCD displays differ in their pros and cons.
In favor of LED-TV
RGB LED displays offer higher levels of brightness, clarity, and contrast because each individual pixel is illuminated (the pixels are essentially LEDs). Thanks to this, a richer and more accurate color reproduction is achieved.
No additional lighting is required, which is why LED screens have a thinner body that can easily find a place on furniture or be mounted on a wall.
These displays are more environmentally friendly because LEDs do not contain mercury, unlike the lamps used in LCDs.
LED-backlit TVs consume 40% less electricity. The uneven illumination of solid matrices also contributes to savings: some areas are darkened, others are brighter, and to create a deep black color on the screen, the diodes in the corresponding areas are simply turned off.
This leads to another plus: better black reproduction than conventional LCD screens.
LED models are often more functional (due to their, so to speak, novelty): they are equipped with a lot of additional connectors and interfaces, wireless communication modules, and also support many multimedia formats.
At the same time, if you compare LCD and LED TVs, you can find many points in which LED models are inferior to standard ones.
In favor of LCD TVs
What makes LCD different from LED TV for the better is its lower cost and selling price.
Although not so bright, contrasting and colorful, LCD models are free from the problems of unnatural colors, color heterogeneity and color spots, which sometimes plague LED models backlit with multi-colored LEDs.
Driving groups of LEDs to solve this problem can cause a slight flicker on the screen, which is not the case with LCD displays.
If LED is deep black, then white is more natural in LCD models.
Conventional LCD displays do not have the problem of “bluing” of the picture, which LED TV owners complain about.
Total
If we talk about the difference between an LCD and an LED TV and which TVs are better: LCD or LED, it is worth noting that there are differences between each other. Compared to conventional LCD models, edge-lit LED TVs consume less energy and are thinner, but do not offer much different image quality. LED TVs made using Direct technology (solid backlighting), on the contrary, are brighter, more contrasty and clearer, but not much thinner and more economical than their LCD counterparts. Each type is good in its own way.
You can read more about the differences between display technologies in the article about smartphone and tablet screens. A
Liquid crystal television models today do not surprise anyone, and they can be found in almost every modern apartment. However, if you have just decided to exchange your old TV for a new one, then when choosing a model you may be faced with the fact that the word LED will be indicated in its name or characteristics. You've probably heard about these types of displays, but before you make your choice in favor of an LED or LCD model, you should understand how one technology differs from another.
Device of LCD and LED TVs
They are two transparent panels with electrodes, between which crystals in liquid form are located. Such crystals are arranged in a certain order in order to be able to transmit a picture. LCD monitors also have filters that create a polarizing effect and color filters to create a color image. In addition, TVs created using this technology have a backlight lamp, which is located at the back of the screen. This lighting is called CCFL.
Ice TVs have exactly the same production technology, only instead of a conventional cold cathode lamp, LED lighting is used for backlighting. That is, a large number of small LEDs are located on the sides of the screen or along its entire perimeter at the back.
As a result, we come to the conclusion that the only difference between these TV models is the type of screen backlight.
What is better anyway?
To decide which TV is right for you, you should familiarize yourself with the characteristics that each of these TV models has.
- Color rendition much better on ice screens, as LEDs allow you to create brighter colors and a greater number of shades.
- Black level and contrast also much better in LED backlit panels. This is due to the fact that the overall backlight of the TV will make the black pixels not dark enough, causing the contrast and black levels to be lower than those of an LCD TV.
- Energy efficiency. LCD TVs do not consume much less electricity than models with LED backlighting, so deciding which one is better in this regard is difficult.
- Price LED TVs are currently still higher than conventional LCD models with the same diagonal and interface.
- Viewing angle. Previously, this was significant, since older LCD models had matrices that could not provide a sufficient viewing angle and when viewing the TV from a certain angle, it looked too dark, or simply distorted the colors. Modern models no longer have this problem, and you can safely buy them. However, the winner in this category can be called an LED TV, since even in the very first models the viewing angle was at least 160 degrees.
- Fast response is currently the same in both technologies. However, if you decide to save money and buy an older model of LCD TV, you may encounter a slow response speed, which is why the picture may have a so-called “trail” when watching a fast-moving video, for example, “Formula 1”.
- Interface In TVs of both one and the other, the technology is the same. Both have support for game consoles, connectors such as MHL, USB, HDMI, and so on.
- Durability. LEDs last much longer than conventional lamps, which means your LED display will last longer.
- Dimensions. Ice TVs are noticeably thinner than conventional LCD displays. This is due to the fact that the LEDs are located around the perimeter of the monitor, and not behind it, so they take up less space.
conclusions
Technologically, there is no difference between LCD and LED TV, but judging by the characteristics, LED technology is still better. Therefore, when choosing a TV model, you should proceed from your own requirements for this device and preferences.
So, if you are going to install the TV near the wall, then you can safely choose an LCD TV model, since you will only see it from the front, which means its thickness will not be significant.
If you want to enjoy a bright, contrasty image and like to watch TV in the evening with dim lights, then it is better to choose a model with LED backlighting, as it has better color rendering and black depth, judging by the characteristics.
Also, LED TVs will look better if you want to place the screen on the wall using a bracket. This way it will protrude much less, which will look better.
However, if ideal color rendition and the thickness of the TV are not particularly important to you, or you do not want to spend a lot of money, then you can choose one of the modern models of LCD displays. To the naked eye there will be virtually no difference.
Usually, LCD TV they are purchased for two reasons: the desire to place the largest screen possible in the smallest area, or as a compromise between a plasma panel, which is a waste of money, and a regular CRT TV, which for one reason or another has ceased to satisfy the buyer’s needs. In the first case, no problem: today there really are no more compact TVs than LCD. This one will fit on a small chest of drawers, in a cramped kitchen, and even on a wall. But as an inexpensive alternative to plasma, such a TV must be chosen taking into account a number of reservations. Firstly, in terms of color rendering quality, most LCD TVs are still inferior not only to plasma panels, but also to traditional TVs: they have a less natural picture and a lower level of color transitions. In addition, the brightness and saturation of colors greatly depends on the viewing angle, so it is not always possible to watch your favorite programs with friends comfortably while sitting around the perimeter of the room. Of course, the exception to the above rules are. They are even smaller in size and also have better color and other image characteristics.
But even the simplest LCD TVs are completely devoid of the main disadvantages of CRTs: screen flickering, large size and weight, problems with beam convergence, geometric distortions and harmful electromagnetic radiation. What is more important is up to each individual buyer to decide, however, if the choice is made in favor of LCD technology, before going to the store it would be a good idea to familiarize yourself with the main differences, characteristics and features of such TVs.
Main characteristics of LCD TV
When choosing an LCD TV, or simply LCD TV, you need to pay attention to the following parameters:
Brightness
One of the most important parameters of an LCD TV is its brightness. It depends on how comfortable it will be to watch TV in a lit room - on a sunny day, in bright electric light, etc. – that is, in a significant proportion of cases. The minimum brightness value today is 350-400 cd/sq.m and allows you to watch TV in a lit room with more or less acceptable quality. However, if the screen is exposed to direct sunlight, such a display will go blind, so if you plan to place the TV near a light source (for example, opposite a window), you should choose a brighter model. Moreover, the price of an LCD TV does not depend significantly on its brightness, since the latter fluctuates in a small range for models of the same diagonal: for example, among 15-inch models its value lies in the range of 400-500 cd/sq. m, in the segment of 26 and 32 inch TVs - 450-600 cd/sq. m, etc. The brightest matrices today are in models from LG and Philips.
Viewing Angles
The second key characteristic of any LCD TV is the viewing angle. The larger it is, the more comfortable it will be for you to watch it from anywhere in the room. In advanced modern models, the viewing angle reaches 160-170 degrees vertically and horizontally, that is, it actually eliminates this problem - such a TV can be safely placed (or hung) anywhere. The 15-inch Sharp LC-15SH1E LCD TV with vertical and horizontal viewing angles of 170 degrees costs significantly more than the LG RZ LCD TV with the same diagonal and all other parameters (and even slightly higher brightness) with 160 and 130 degrees vertical and horizontal. As the diagonal increases, this difference will become even more significant.
Connectivity
The third important point that is often forgotten when buying an LCD TV is the ability to connect it to various devices, primarily DVD players. Manufacturers, as a rule, equip LCD TVs with standard RGB connectors for TV/video equipment: SCART, Component, S-Video. Before purchasing, it is useful to read the documentation for the devices with which you plan to connect your new TV and make sure that the interfaces of the same name are available for connection.
A word about pixels
Another parameter is the number of dead pixels. These are pixels that are constantly on in one state and do not change their color depending on the signal. Different manufacturers allow different numbers of dead pixels on the screen, which is stated in the instructions for using the product. For example, the instructions may say “if you find no more than four non-functional pixels on the panel, then the panel is considered fully operational.” In, as a rule, the presence of non-functioning pixels is not allowed at all, since we look at the monitor from a much closer distance than at the TV, and we can immediately see this “garbage”. However, several of these points on the TV will attract attention, so you should definitely check their presence before purchasing.
Matrix response time
In addition to the parameters listed above, the characteristics of almost every LCD TV also indicate the response time of the matrix. In order to understand what this characteristic means, let’s take a short technical excursion. Any LCD screen is a translucent type screen, which is illuminated from the back with a white lamp, and the cells of primary colors (RGB - red, green, blue), located on three panels of corresponding colors, transmit or do not transmit light through them, depending on applied voltage. This is why there is a certain delay in the image, especially noticeable when viewing fast-moving objects. The degree of this delay characterizes the response time; accordingly, the smaller it is, the better. In modern models, this indicator usually ranges from 8 ms (1 ms is one thousandth of a second) to 16 ms and depends on the type and size of the matrix. In addition, different manufacturers measure this indicator differently (usually to their advantage), so it is only really important when choosing between different models of the same brand. In other cases, it should be taken into account, but checked in practice - for example, in a store, see how the dynamic scenes of the model you like are shown. And it is quite possible that a TV with a longer response time (according to the documents) may work better than one with a shorter response time. The record holder for response time is Philips - for some of its models it is only 6 ms. For example, a 32-inch LCD TV has a Philips 32PF9966/10.
Screen resolution
Another, no less important, but no less controversial indicator is resolution. The fact is that the best picture is obtained when the physical resolution of the matrix is equal to the resolution of the input signal. For this reason, for watching DVDs (and it is still difficult to find a higher-quality signal), the resolution of 720x576 is ideal, but there are no TVs with such a matrix on the market yet. To watch TV shows on TVs with an aspect ratio of 4:3 and a small diagonal (up to 26 inches), a resolution of 640x480 pixels is quite enough.
On large diagonals (after 32"), they are being “sharpened” not even for DVD, but for high-definition television (HDTV), which is already becoming the standard for video images all over the world. The resolution suitable for such a signal is -1920 × 1080 (Full HD), but such TVs cost a lot of money. Therefore, just like response time, resolution should be taken into account, but not make it the determining criterion when choosing. In addition, according to this indicator, it makes sense to compare only TVs with the same diagonal.
The same is true regarding contrast - if a couple of years ago it was one of the most important characteristics of LCD panels, today technologies make it possible to make it sufficient even on inexpensive panels and feel the difference between matrices with this indicator equal to, for example, 500:1 and 600:1 is not possible for every person and not on every TV. The physical meaning of this indicator is as follows: if a TV has a contrast ratio of 600:1, this means that the darkest areas of the image differ in brightness from the lightest by 600 times. True, when companies indicate this parameter, they do not indicate how they measured this contrast, but in a dark or light room we will get different results.
Lamp life
You also need to pay attention to the operating time of the lamp. For most modern LCD TVs, at almost maximum brightness, it is 60,000 hours (that's enough for about 16 years if you watch TV 10 hours a day), although there are devices on the market with shorter lamp life. For comparison: for plasma TVs, the brightness decreases much more during the same time, and for CRT TVs (here, however, the phosphor burns out) the threshold is 15,000-20,000 hours, then the quality deteriorates noticeably. To summarize, we can advise you to ask yourself questions in the following order before buying an LCD TV: what it shows, what it looks like, who the manufacturer is, what the technical parameters of the model are.
