What does led backlight mean? What is LED backlighting? Types of backlight. LED lighting throughout

IN Lately Many people are concerned about the question of what is an LED TV? These units have proven themselves well and managed to gain wide popularity. The cost of this is gradually decreasing, making them much more affordable. Not everyone understands what an LED TV is, so it’s worth understanding the principle of its operation and discussing the pros and cons associated with production technology.

Essentially, this device is a liquid crystal TV in which the screen is illuminated using LEDs. Earlier models of LCD TVs use cold cathode lamps. It is worth mentioning the advantages of using LED matrix in the backlight. Manufacturers talk about significant increase image quality. There are a number of parameters that have a direct impact on how viewers perceive an image. These include brightness, contrast level, black depth and color rendering quality. In most cases, LED-backlit TVs are significantly ahead of their counterparts.

If we talk about what an LED TV is, then it’s worth saying that the mentioned feature is associated with design features By adjusting the glow level of the diodes, it is quite possible to achieve absolute control over the brightening or darkening of certain areas of the screen. When turned off, the LED does not create any glow, so a group of turned off diodes creates completely black areas. Thanks to the use of this technology, it is possible to achieve deep black color display, as well as excellent contrast levels. Overall color rendition also becomes significantly better, which has a positive effect on image quality. Thanks to the glow of LEDs, LCD LED TVs have high brightness screen. Using a diode matrix allows you to make most of the parameters that are responsible for the output high-quality image, much better. The significant reduction in energy consumption is another major benefit.

Speaking about what an LED TV is, it is necessary to mention that harmful aerosols and mercury are not used in production, and this has a beneficial effect on B. Both single-color and three-color diodes can be used, which can significantly increase the number of displayed colors. It is common practice to use white LED backlights, which reduces the risk of image problems.

Manufactured using "local dimming" technology, which is responsible for local dimming. According to it, LEDs are controlled in groups consisting of several individual elements. The disadvantage of this technology is the possibility of poor uniformity in the output image. Usually this is the appearance of bright spots in areas where the backlight is brightly turned on and dark spots where the backlight is completely turned off.

LED is not a separate type of display, but one of the types of LCD backlight, that is, an LED TV means a monitor using liquid crystals (LCD TV, liquid crystal), which has an LED backlight type. What does it represent similar technology, let's look into it further.

What kind of technology is this?

The abbreviation LED stands for “light-emitting diode”, which means “light-emitting diode” or simply “light-emitting diode”. The essence of the technology is the glow of semiconductor materials under the influence of electricity. It has been known since the middle of the last century, but widespread industrial implementation began relatively recently.

The technology is implemented using to the following principle: behind the main screen that the viewer sees are point sources lights - LEDs. The light they emit passes through the screen, undergoing certain transformations along the way, and thus the final image is formed. You can see what such a screen backlight system looks like in the photo:

LED technology allows you to achieve the most profitable this moment the ratio of costs to the quality of the generated video, which is why it is actively used by modern producers.

How is it different from other technologies?

To accurately highlight the advantageous qualities and features of LED, it is worth comparing it with other methods of creating moving pictures.

LCD

Stands for “liquid-crystal display” and means that to backlight the screen with reverse side Light sources are also used, but they use ordinary fluorescent lamps (fluorescent). The service life of such lamps is relatively short, and the brightness decreases greatly over time. In addition, their production uses very harmful chemicals - mercury compounds.

The brightness of conventional LCD displays is low. The fact is that light on its way from the lamps to the viewer passes through several layers of diffusers and rotating cells of liquid crystals. At the same time, clear black color is not displayed because some of the light still “leaks through” the closed crystals. The dimensions of the lamps are quite large, so such screens cannot be ultra-thin. But LED is a direct descendant of LCD, so fundamental differences not so much.

Plasma

Plasma TVs, on the other hand, use a completely different method of creating images. Unlike LEDs, they do not require artificial backlighting at all - each pixel on the screen emits light itself. Thanks to this, the brightness of the images of plasma panels is unrivaled, and they are often installed outdoors. However, energy consumption is also high when compared with other competitors.

Cells tend to burn out quickly, that is, lose brightness when permanent job. And the constant presence of the same TV channel icon in the corner of the screen will burn out the involved cells, which will be noticeable when switching the channel.

OLED

Means "organic LED". The technology is based on organic light-emitting diodes. IN in this case The word “organic” does not mean LEDs made from living tissue, but semiconductor chemical compounds – polymers containing carbon.

Compared to LED TVs, such TVs are brighter, more economical, do not require backlighting, the image is not distorted at any angle, and the contrast is considered infinite. However, at the moment there are still many problems - they are very sensitive to air humidity, LEDs of blue color They lose their luminosity quite quickly (within a couple of years), the service life of the screen directly depends on the brightness. The price also remains high.

QLED

Not long ago, Samsung announced QLED technology. This abbreviation stands for “quantum LED” (“quantum light-emitting diodes”). Each subpixel on the screen is not a color filter (one of three colors), but a full-fledged blue LED, but red and green colors are generated by the so-called " quantum dots“- zones on the screen that, when light falls on them, begin to emit light. blue light falls on them from the back, and they themselves emit red and green colors towards the viewer.

Such screens are still quite expensive and rare, but they have many advantages, including long term services, minimal energy consumption, low cost and low cost of switching to new type equipment. They also change shape very easily, making them the best candidates for the display surface of flexible tablets.

Types of LED backlights

There are several common types of LED backlights that are used in the production of LCD TVs.

EDGE

Literally translated as edge or edge. In this case, we mean that the LEDs are located around the perimeter of the rear of the case. This also means that there are simply no light sources in the center of the screen. To create uniform brightness over the entire screen area, a special translucent diffuser substrate is used.

The position of the LEDs virtually to the side of the image allows for an exceptionally thin body.

(RGB LED)

Direct means direct or immediate. With this design, the LEDs form a kind of matrix, evenly distributed over the rear surface. This provides extremely precise control over brightness at every point in the image, but at the same time does not allow for the production of ultra-thin bodies. There is a clear difference from previous type can be seen in the picture below:

Sometimes manufacturers use not white LEDs, but three colors - red, green and blue (RGB - red, green, blue). This allows you to achieve much better color, brightness and contrast, although the price for such aesthetic delights also increases.

WRGB LED

This is a combined technology, where “W” means “white”, that is, in addition to color ones, a fourth, white, LED is also used. This trick makes the image brighter if necessary, and energy consumption due to the reduced load on color LEDs, on the contrary, is less. This technology is promoted by LG.

Which LED TV to choose?

LED TVs are the undisputed leaders both in terms of sales and price-quality ratio, so you can make your choice from the most popular screen models with similar backlighting and a 42-inch diagonal.

This is a representative of the Quattron family, fundamentally different from all other manufacturers in the colors of the matrix. LEDs are traditionally located around the perimeter of the case, but in color scheme There are not only traditional colors (red, blue and green), but also additional yellow, which makes the image more natural. This is a Sharp exclusive feature.

Frame rate – 200 Hz, digital tuner for all popular formats, LAN via Wi-Fi and twisted pair (and support for Skype, only the camera will have to be purchased separately). You can watch the video in MKV format, although not all types. Flash drive or external HDD must be formatted as FAT or NTFS, but Blu-ray format or DVD is not supported. There is a Time Shift option - recording to a flash drive or USB drive with delayed viewing.

The only drawback is that the processor sometimes does not handle complex color transitions correctly, which is not a problem for dynamic scenes.

Interesting model, which is missing Smart function TV, but there is also a built-in browser, YouTube, and Skype (a proprietary camera with a built-in microphone must be purchased separately). The device is equipped with sensors, one of which evaluates the light level and automatically adjusts the brightness, and the other detects the absence of spectators and also automatically turns off the device after a certain period of time. The built-in player has limited functionality.

The TV simply has no direct disadvantages, although there is a peculiarity: when the dynamic adjustment mode is turned on, the brightness seems excessive, but when the dynamics are turned off, scenes with low lighting.

This model is the cheapest member of the 3D Cinema family. Horizontal rows of pixels on the screen emit polarized light—even ones for the right eye, odd ones for the left. Such an image is normally perceived by the naked eye, and at the same time creates a 3D effect when using proprietary lightweight glasses with passive polarizers. In this case, the image does not flicker or overlap, no batteries are needed.

However, for such ease of use you will have to come to terms with two small drawbacks:

reduced resolution, because the image is actually created through a line;
suboptimal contrast.

Embedded system intelligent control brightness is intended to smooth out this barely noticeable flaw.

The TV is equipped with a player that can easily reproduce the MKV format and digital standards broadcasting.

Integration into the world modern technologies The connection is not the most impressive: Skype is not available, a USB video camera or keyboard cannot be connected either, although it is possible to access weather and news sites thanks to the Viera connect service. There is no 3D mode at all.

These shortcomings are commented on by the quality, which is the best of all the models offered in this review. Aesthetes simply have nothing to complain about. All colors are completely natural, and the movement of any objects looks absolutely natural. This is facilitated by the built-in proprietary system“frame insertion”, designed to eliminate blur and flickering of the image.

The most affordable copy of a number of models designed for viewing 3D films through special “shutter” glasses. It is assumed that the consumer either already has such glasses or can easily buy them separately. This is a justified marketing ploy.

The hardware is quite modern:

digital tuner for analogue and digital TV popular formats;
network card with an RJ-45 connector (for Wi-Fi you will have to buy a special dongle);
Smart TV function.

However, the main feature of this model is playback with external media, that is, flash drives and plug-in disks. The proprietary image optimization algorithms used create an amazing picture without blur, areas with unclear colors and other artifacts. This becomes especially noticeable when watching videos in “heavy” formats like MKV with a file size of 40 GB.

In addition, the viewing control system is well thought out - right from the remote control, you can rewind the recording with one touch, mark the necessary moments (to instantly return to them), and so on.

Video: how does an LED TV work?

In the short video below, the master disassembles a Samsung LED TV and shows how it works:

So, LCD TVs with LED technology are in great demand because they represent optimal ratio prices and quality. The variety of such screens is amazing; everyone can choose a TV with the optimal functions for themselves, for example, SMART, Wi-Fi, satellite tuner or webcam.

In contact with

Modern LED TV, what kind of device is it? In fact, this is an ordinary TV receiver with a liquid crystal screen, the backlighting of the matrix of which is carried out by a specially selected and specially located set of LEDs ( Light Emitting Diode).

It would be more correct to call such devices LCD (LCD) TVs with LED backlighting, but the manual Samsung, which was one of the first to release such TVs on the market, began to use the term “LED TV” for marketing purposes, which over time took root and became widely used. In fact, in these TVs, the LEDs do not constitute a real picture unit (pixel), so they cannot be considered true LED models.

We can say that LED-backlit TVs are a more advanced version of LCD models that previously used CCFL cold cathode fluorescent lamps as a light source. Replacing the CCFL backlight with LED has made it possible to eliminate a number of traditional disadvantages from LCD TVs: they have become noticeably thinner (this is especially noticeable in Edge LED models), more energy efficient and environmentally friendly, since they do not contain mercury and do not require special disposal procedures.

Today, several types of LED TVs are produced, which differ from each other in the type of LEDs used, as well as in the order of their location in relation to the screen.

By LED color:

Single-color systems (White LED);
Multi-color systems (basic color triad RGB LED);
Mixed systems (such as Sony Triluminos).

White LED TVs can be considered the most budget-friendly solution, devoid of the traditional disadvantages of devices with CCFL fluorescent lamps. However, they create an image with a similar color gamut and the same depth of contrast.

Models with multi-colored RGB lighting allow you to significantly expand color palette due to flexible LED brightness control different colors. Thanks to this, the number of color undertones increases. True, to support such technology requires a more powerful GPU, and the TV itself begins to consume more electricity and increases significantly in price.

An even wider color gamut is demonstrated by Sony's proprietary Triluminos screens used in the Bravia line, which use blue backlight LEDs and a special film with red and green quantum dots. The use of quantum dots can significantly reduce the energy consumption of such LED TVs.

In order of LEDs:

Directly behind the LCD matrix (direct backlight type Full or Direct LED);

Along the perimeter of the LCD matrix (lateral type of Edge LED backlight).

Now let’s take a closer look at the question of what an LED TV is from the point of view of LED placement.

End Edge backlight LED, in which LEDs are located on one (usually the bottom), two (side) or all four sides of the TV screen, allows you to create models with a body thickness of less than 1 centimeter. Such devices always use white LEDs.

Among weak points of such models (in the budget niche), one can note specific “lights” along the edges of the screen where the LEDs are located, as well as relatively high level demonstrated contrast. In addition, Edge LED TVs are somewhat more expensive than models with direct backlighting, as they require the use of special system light guides, reflectors and diffusers for uniform distribution of light across the screen.

Carpet-backlit Direct LED TV models are not as thin as Edge LED, but they are cheaper and offer higher contrast levels due to the simplicity and effectiveness of Local Dimming technology. In addition to conventional white LEDs, they can use backlight technologies with diodes of different colors, which greatly improve image characteristics.

Last time CRT TVs have practically sunk into oblivion - you can no longer find them in electronics stores, except perhaps in some homes. But thin, narrow TVs are not considered a luxury at all and are used everywhere, with new models with improved technologies being released every year. Therefore, it is often difficult for potential buyers to make their final choice." blue screen"among the abundance of goods offered. We will tell you what it is and its advantages.

What is LED technology?

In general, LED is an abbreviation for English language, which stands for “light-emitting diode”. The phrase is translated into Russian simply - LED. And if we talk about what an LED TV means, then in fact it can be called an advanced LCD TV.

It is known that LCD is a technology based on the use of a liquid crystal matrix. The latter consists of two plates, between which liquid crystals are placed. When exposed electric current they start to move. But thanks to the backlight, dark and light spots appear on the matrix surface. And color filters located behind the matrix make the image on the screen color.

Regarding what LED backlighting is, it is used as a light source a large number of LEDs (as opposed to LCD backlighting, which uses cold cathode fluorescent lamps).

Thus, the operating principle of an LED TV is based on illuminating the liquid crystals of the matrix with LEDs.

Advantages and disadvantages of LED TVs

TVs with LED technology have a number of advantages. Probably the main advantage is the reduced use of electricity: according to experts, up to 40% of monitors in which the backlight is provided by fluorescent lamps.

In addition, an LED monitor will easily fit into any interior - LEDs allow you to create monitors up to 3-3.5 cm thick, because in fact LEDs are very tiny. Moreover, this is not the limit. By the way, there is a difference in the arrangement of LEDs in LED TVs, which determines the thickness of the matrix. In the case when they are evenly placed behind the TV panel, they say Direct LED. Thanks to this, the screen is illuminated evenly. You've probably heard about the extremely thin Edge LED TVs. As for what Edge LED backlighting is, this is the name given to the arrangement of LEDs around the perimeter of the screen with the simultaneous use of a diffusion panel. Due to this, the width of the panel is significantly thinner - less than 3 cm! By the way, in electronics stores you often see Slim LED in the model designations - what is it? This is a marketing designation for televisions with a minimum body thickness of 22.3 mm. Typically, such models visually lack such a familiar frame around the screen, although in reality it is located under the screen glass.

Significant advantage LED TVs You can also call it an improvement in image quality. Thanks to the implementation of complete control over the lightening and darkening of local areas of the screen, the black color really turns out to be deep. The overall color rendering becomes better and the image brightness is higher. By the way, you can watch your favorite TV series from all corners of the room without fear of darkening the image.

Main disadvantage of LED TVs are considered to be expensive in relation to TVs with other types of backlighting. However, it is believed that as technology improves, the production of LED-backlit TVs will become widespread, and therefore the price will gradually decrease.

Models of LED-backlit TVs dominate the market and deservedly so. In this article we will look at the types of LED backlights modern TVs and evaluate their effectiveness.

LED TVs

Let's start with the fact that LED TV is not a new type of HDTV. . Unlike plasma and OLED TVs, which are manufactured on the basis of emitting technologies, where each pixel is a separate light source, in liquid crystal models, each pixel of the LCD matrix requires lighting (from behind or from the side through a lens system). So LED HDTV models are the same liquid crystal (LCD or LCD) TVs, but they have a built-in light-emitting diode (LED) backlight, which replaces the standard one fluorescent lamps cold cathode (abbreviated CCFL).

2 types of LED backlight according to design: matrix and side

LED backlighting with local dimming. First, televisions with LED backlight, used to illuminate the cells of the LCD matrix " full array"(full array) of LEDs, similar to standard TVs based on backlight using CCFL lamps. But to change the thickness of TVs downward, the developers abandoned the use of a full array of LEDs behind the screen, installing lines of light sources on the side of the LCD panel. Thus, the distribution of light from LED sources over the entire screen area is carried out using specially shaped LEDs. Model data LCD TVs called TV with side or regional LED backlight, which still dominate today.

LED lighting with local dimming system allows you to automatically reduce the brightness or turn it off completely separate groups backlight sources. Most modern LCD TVs with LED backlighting are equipped with a full array of LED sources placed behind the LCD panel. dynamic backlight technology also called local or local dimming. Using local dimming, certain areas The overall array of backlight LEDs become darker or lighter depending on the brightness and color of the corresponding part of the image on the screen.

The ability to darken a specific area of the screen can reduce the amount of light that passes through the closed pixels of the LCD panel, which has a positive effect on the rendering of blacks, which become darker and more realistic. Because black levels are critical to contrast, the perception of depth on black surfaces, full-color images become more vibrant and clear. Local dimming technology has the only drawback - the effect of local dimming, which is formed when part of the light from brighter zones leaks into neighboring darker ones, which subsequently brightens the border dark color. It is quite difficult to notice the clouding effect on most models, since the disadvantage is directly related to the number of local dimming zones behind the screen, and manufacturers do not always provide such information.

When using standard backlighting using CCFL lamps and in most LCD TVs with edge LED backlighting, all backlight sources brighten or dim at the same time (the so-called " global dimming"), but among TV models from Samsung and LG there are rarely displays with side LED backlighting, which can also work on the principle of local dimming (“precision dimming” for Samsung and “LED Plus” for LG). To put it simply, this is a local dimming sham.

Thin models with side LED backlight Of course, they suffer from uneven screen illumination, but not everyone. Main feature of TVs with side LED backlighting– thin body, therefore it is difficult to ensure uniform distribution luminous flux across the entire screen plane. When purchasing a TV, play an image of the white surface on the edge-lit LED display screen to check that there are no brighter areas around the edges of the screen. Likewise, when the screen is filled with a black field, the edges should not appear lighter (gray).

It is also worth noting that LED backlighting, regardless of the type, does not improve the viewing angles of the LCD panel. Black level at using LED illumination and a possible shift in the viewing angle by 1-2 meters to the left or right falls.

We must not forget about the energy efficiency of LED backlighting. Of course, the consumption of any model is significantly affected by the size of the screen and the brightness of the backlight sources. LCD TV models of both varieties of LED backlights are much more energy efficient compared to plasma models.

LED backlights for LCD displays are divided into categories according to the following criteria:

glow color: white or RGB;
lighting uniformity: static or dynamic;
design: matrix or side (this is described in more detail above)

RGB backlighting is used to fine-tune the light spectrum. In addition, additional compensation for changes in the emission spectrum of LEDs over time is often applied. LED TVs with RGB LED backlighting light up different areas of the screen depending on the color of the picture. Colored backlighting provides enhanced contrast and deep blacks, as demonstrated by many Sony LED TVs.

Edge LED: Better Color Rendering

Sony in new flagship models TVs - for example, the W905 line - uses Triluminos technology. The LED backlight (Edge LED) built into the frame of the TV on all sides of the screen is complemented by so-called quantum dots - fragments of a semiconductor several hundred atoms in size that emit light in a strictly specified range. Triluminos technology is designed to minimize color distortion and provide enhanced red and green tones. This will allow you to achieve an extremely uniform and natural image with a significantly wider color gamut. Tests of the first devices with Triluminos support did not disappoint us: color gamut Sony models KDL-46W905A is comparable to the coverage of solutions based on organic LEDs(OLED) and is not achievable for LED-backlit LCD TVs. The W805 and W605 series devices, which also went on sale this year, do not use Triluminos, making their cost significantly lower. In the future, manufacturers will be able to completely abandon LED backlighting in favor of quantum dots.

OLED TVs: brightness and color at their best

TVs with OLED screens have already reached stores, and developers have rushed to release new models with concave displays. Last year, LG planned to introduce a 55-inch OLED TV to the market, but it only went on sale this summer. In Russia, the 55EM9600 model and its improved analogue 55EM9700 will cost the buyer 500,000 rubles. In addition, the device is sold in Europe, the USA and some other countries.

Advantages of OLED TVs: it is not a type of backlight, but a different technology

accurate color reproduction
greater brightness margin compared to other technologies
high contrast compared to LCD models (another imaging technology).
absence of an LCD matrix and LED backlight - their place was taken by a matrix made of light-emitting organic diodes.

Samsung and LG independently developed OLED TVs with concave screens (Curved OLED). This design is designed to minimize distortion at the edges of the image and increase detail. New items are still available in limited quantities in South Korea, USA and some European countries. 55-inch Samsung model KN55S9C is priced by the manufacturer at $9,000 (300,000 rubles).

Of particular interest is also Multi-View technology, implemented in many models of OLED TVs with both flat and concave screens. Due to the extremely short response time similar devices allow you to simultaneously demonstrate two or four programs in high definition format (Full HD) or two different films in 3D format. Shutter glasses are used to separate the image. Each viewer, using controls located on the glasses, can select individual program to view. At the same time, thanks to the built-in headphones, playback of the soundtrack corresponding to the film is ensured.