Monitors with LED backlight. Features of LED TVs with Edge and Direct backlighting

Today there are such a variety of TV models on the shelves that the consumer is simply lost and does not know what to choose. Before your eyes are dozens of screens of different sizes and thicknesses with incomprehensible words on explanatory signs. For example, if the sign indicates that the TV type is LED, what does this mean?

You know that the screens of some modern televisions are a liquid crystal matrix. If the matrix is ​​illuminated from the inside with special LEDs, this means LED TV.

What is LED TV backlighting?

Edge LED

If you disassemble the TV, then behind the liquid crystal matrix along the perimeter of the body you can see many diodes that look like small light bulbs - this means that the TV has side lighting. The diffuser makes the screen illuminated evenly, but the backlight cannot be adjusted.

Matrix backlight (LED Backlight)

It is carried out by groups of diodes of three colors located over the entire surface of the panel. This method of illumination allows you to adjust it to separate areas, which allows you to achieve better color rendering.

What does LED TV mean for the consumer?

It is believed that this type of TV has a number of advantages over a conventional LCD TV.

What are the differences between LED TVs?

• TVs of this type have a more contrasting image;
• the colors are very rich and natural;
• LED TVs consume less energy;
• The LED TV body is thinner;
• The TV is capable of displaying a high-definition signal;
• Screen viewing angles are maximum.

TVs are equipped with a number of connectors for connecting various devices and are even able to connect to the Internet.

Characteristics of LED TVs

• permission. The resolution of LED TVs can be: Full HD and HD Ready. Full HD - the most high resolution;
• sweep frequency. The scan frequency can be up to 960 Hz. More high frequency scans will be required for 3D TVs;
• matte or glossy screen. Glossy finish There may be glare on the screen. On matte, the viewing angle is not so great;
• . If you are going to watch 3D movies, then choose between two display technologies and two types of glasses: active and passive. Determine by viewing which type is more suitable for you, is not irritating, and is comfortable for the eyes.
• smart function. Smart function will come in handy if you are going to go online. Choose a model with or without a built-in router.

So, you have made your decision and decided to purchase an LED TV. Where do we start choosing?

How to wipe LED TV?

In addition to all sorts of special liquids and wipes, which are available in abundance on store shelves, the TV is wiped with microfiber cloths. First slightly damp and immediately dry.

Using our tips, you will be able to choose the LED TV that best suits your needs and can save on features you don’t need.

Most homes have more than one TV. Maybe two, three or more. They are installed in different rooms - in the kitchen, in the living room, in the bedroom or in the nursery. Depending on the place of “registration”, the requirements and selection criteria change. So it turns out that choosing a TV is not so easy.

To choose a TV, you first need to decide at least on the technology by which it will be manufactured. They all have their pros and cons. But even the disadvantages can be used for good.

Plasma screens

The design of a plasma panel is fundamentally different from all other technologies. Between two glass plates there are cells filled with gas - xenon or neon. That’s why such TVs are sometimes called gas-discharge TVs. When current passes, the cells glow, the brightness of the glow depends on the magnitude of the current.

The main advantage of this technology: high quality of the “picture”, which is preserved even in very dynamic moments. Other advantages of this technology are no less impressive:

Very good indicators that contributed to the rapid growth of popularity. But there are also disadvantages:

If you want to choose a TV with a large screen, high-quality image and good color reproduction, pay attention to plasma panels. This is exactly them. Only if you want, you will have to look for appropriate brackets and the wall must have good load-bearing capacity. Drywall or foam concrete will not hold such a mass.

Properties of LCD TVs (LCD)

LCD screens use digital way image transmission. They are so named because the cells are filled with liquid crystals, which in an electromagnetic field polarize the light passing through them, changing the degree of their own transparency. To obtain an image, a matrix with liquid crystals is illuminated from behind (cold cathode lamps), and color filters are used to convey shades.

Advantages LCD TVs the following:

• Recent models have low power consumption.
• Higher resolution (compared to plasma).
• Possibility of playback in FullHD format.
• Light weight.
• There are screens different sizes- both small and large. The image on them has the same quality.
• Good image geometry.
• Low level electromagnetic radiation since they are powered by reduced voltage.
• There is no screen burn-in or see-through.
• The screen does not attract dust.

A similar set of qualities contributed to the rapid spread of televisions with liquid crystal screens. But they also have a number of disadvantages that are worth knowing about:

If you want to choose an LCD TV with good resolution, you will have to shell out a substantial amount. If the requirements for image quality are not so strict, it is quite possible to look at models from the mid-price range.

LED technology

The difference between LCD and LED TVs is various lamps, used to illuminate the matrix. LED TVs use LEDs. They are smaller in size, which allows for very thin screens. They are also more durable and consume less electricity. There are two types LED backlight screens:

Through the use of LEDs, LCD TVs receive additional advantages:

If you decide to choose a TV with high quality images, take a closer look at the LED models. They have, perhaps, only one drawback - the high price. Good quality led tv costs $600-1000. Compared to conventional LCDs, they cost 40-50% more. However, these are not the most expensive models today and many people opt for LED TVs.

OLED and QLED technology

This technology for making televisions appeared already in this century, and they have been mass-produced for only four years. The image is formed by organic light-emitting diodes, which emit light themselves and do not require backlighting. In English they are designated OLED, which gives the name to this type of TV.

Today there are two main production technologies OLED TVs:

The first technology turned out to be not the most successful. Due to the nature of production, it turned out to be difficult to find groups of LEDs with the same glow, which led to a large number marriage. For this reason, this technology is at the moment recognized as unprofitable and all OLED TVs are made based on white LEDs. What is the difference between receivers of this type? Here are their advantages:

What are the disadvantages of this technology? First of all, it is the price. OLED TVs cost 4-5 times more than the cheapest LED ones. In addition, there are still very few videos released in 4K quality that will allow you to appreciate the benefits of such screens. Therefore, if you do not need to support HDR-10 or Dolby Vision, you don’t need such a TV. At least for now. Still, there is nothing special to watch in the required quality. You can, of course, choose a TV in the long run - in 10 years this format will become familiar. But as technology develops, it becomes cheaper, so paying now a considerable amount for a new product is at least irrational.

But OLED is not latest news. The latest technology is QLED, but it is even more expensive and therefore, for now, even more irrational.

How to choose TV screen size

You need to choose a TV according to the size of the room. Or rather, by the distance from the viewing location to the location of the screen. The larger the screen, the farther above it is located. Also, the distance to the TV depends on the screen resolution. The higher the resolution, ( more pixels per centimeter), the closer you can sit.

Experts believe that this is the only way to enjoy a realistic image and examine the smallest details. But not everyone is happy with this regime. It's too hard on the eyes. On average, it is believed that the distance to the screen should be at least three diagonals, but no more than 4-5.

Actually, based on this, you can choose the diagonal of the TV. You know at what distance you will sit, you can calculate what size screen will suit you. You just have to remember that the smallest plasma screens have a diagonal of 32″, and Full HD resolution is only available from 21″.

When choosing a location, also remember that for comfortable viewing The middle of the screen should be at eye level.

What technical parameters should you use to choose a TV?

Despite the fact that modern TVs are based on different technologies, their selection criteria are the same. There are about 10 parameters that are worth paying attention to.

Perhaps these are all the characteristics that you should pay attention to if you want to choose a TV for your home. There is little point in going into even greater technical subtleties.

What else to pay attention to

There are a number of other features that are worth paying attention to, but which are not technical characteristics.

Availability of multimedia connectors

If the TV has connectors for connecting other devices, this greatly expands the possibilities of its use. There may be such connectors as HDMI, SCART, USB. Here's what they can provide:

To reduce costs, multimedia connectors are not installed, but their presence really wouldn’t hurt. And it is better to choose a TV in which the connectors are located in front (under a special cover), and not in the back. It will be much more convenient to use.

Supports 3D and SmartTV modes

The 3D mode allows you to see the image in three dimensions, “volumetric”. But you can only watch films/shows/programs recorded in this format in this mode. There are not many of them, and the effect will only be impressive on the big screen.

3D is not the best required function, although interesting

TVs that support the SmartTV function are practically a subtype of a computer or smartphone with the ability to connect to the Internet. In the most “standard” version, it is possible to access social networks and some voice and video messaging services. For more expensive models smart TVs It is possible to use Skype, surf the Internet using the built-in browser, watch video and audio recordings from the Internet (not necessarily only free content).

Picture in Picture

This feature allows you to watch two channels at the same time. How can you use this property? To watch programs without advertising. During advertising, you can turn on another program that interests you, and then switch to the “main” channel.

Frame within a frame - may be useful

Curved screens

TVs with large screens they began to do not only with straight, but also with curved screens. Manufacturers claim that this improves perception. For those who sit exactly opposite, perhaps there are some positive changes. But if several people are sitting in front of the screen, then those sitting on the sides experience serious discomfort - the proportions are distorted due to the curvature of the screen.

When you consider that a TV with a curved screen costs significantly more than a similar “straight” one, it becomes obvious that this is not the wisest use of money.

Ability to delete unnecessary channels

If you plan to use a satellite dish, this feature will be useful. Because without it you will have to manually rearrange the encrypted channels in the end of the list. This is a long and necessary procedure and it is better to avoid it.

Delete unnecessary channels — useful feature when connecting satellite dishes, so you need to choose a TV for satellite TV with this option

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 which matrix 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, however, the management of Samsung, which was one of the first to launch such TVs on the market, began to use the term “LED TV” for marketing purposes, which over time took root and became widely used. be used. In fact, the LEDs in these TVs 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).

TVs with white backlight White LED can be considered the most budget 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 backlighting allow you to significantly expand the color palette due to flexible adjustment of the brightness of LEDs of 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 (side backlighting type Edge LED).

Now let’s take a closer look at the question of what an LED TV is in terms of placement of LEDs.

Edge LED edge lighting, 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 the 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 several more expensive models with direct illumination, as they require the use of a special system of 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 efficiency 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.

Models of LED-backlit TVs dominate the market and deservedly so. In this article we will look at the types of LED backlights on 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 made 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 cold cathode fluorescent lamp (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 LED LEDs behind the screen, installing the light source lines on the side of the LCD panel. Thus, the distribution of light from LED sources over the entire screen area is carried out using LEDs special form. These LCD TV models are 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 completely turn off individual groups of 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, specific areas of the overall backlight LED array 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 at 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 the models Samsung TVs and LG, displays with side LED backlighting are rare, which can also operate 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 – slim body, therefore it is difficult to ensure uniform distribution luminous flux across the entire surface of the screen. 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. The black level drops when using LED backlighting and possibly shifting the viewing angle by 1-2 meters to the left or right.

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 types of LED backlighting 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 The KDL-46W905A has coverage comparable to organic light-emitting diode (OLED) solutions and unmatched by 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, 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 can use the controls located on the glasses to select an individual program for viewing. At the same time, thanks to the built-in headphones, playback of the soundtrack corresponding to the film is ensured.

LED lighting in modern TVs with liquid crystal screens today has several technological solutions. In an effort to increase the color gamut to better display colors, TV display manufacturers have developed new backlighting methods that differ from conventional LEDs.

RGB LED

To obtain a wide spectrum of white light, they began to use triads of LEDs consisting of blue, green and red colors in the backlight.

It was an alternative to WLED with a white LED and a smaller color gamut. The lighting system with three different LEDs is called RGB LED. The color gamut of screens with RGB backlighting was greater than those using only white LEDs or using fluorescent CCFL lamps. But there were also disadvantages: price, size, weight, different times aging of LEDs of different colors, which over time led to image color detuning. Therefore, we abandoned RGB LED backlighting in favor of WLED.

RGB LED

WLED

Given the shortcomings of RGB backlighting, TV manufacturers have settled on using “white” LEDs. They are located either on the sides of the case or in one array behind the LCD matrix. With the help of special diffusers, the light from the diodes is evenly distributed across the entire screen.

Although we call these LEDs “white,” they actually emit blue light, which passes through a yellow filter and is converted to white. Therefore, the use of white LEDs in screens back in 2010 gave a bluish tint to the image.

Over time, manufacturers have improved the components, and the WLED backlight has become quite functional, but as far as the light spectrum is concerned, some imbalances in the display of colors are noticeable.

This peak in blue is due to the blue LED. Using a filter you can get white light. And this filtered light hits the red, blue and green subpixels to form the entire spectrum of the limited color gamut. Passing through filters, part of the spectrum is lost, and the flux intensity at the frequency corresponding to blue will be greater than at red and green. Using screen calibration you can get correct colors, but these reasons allow the WLED-backlit screen to display colors in only sRGB space.

If a display with WLED displays colors in the picture close to blue (shades of blue), then the advantage in the spectrum is precisely blue may put pressure on other colors that will be mixed to create the shade. Therefore, shades close to blue may not be displayed correctly.

This problem also occurred when using a CCFL lamp, but there the problem was with green. It was in green that the peak intensity was visible.

Increased color gamut

To expand the color gamut beyond sRGB and move to the next color standard, changes were made to the WLED backlight.

And after the changes they began to use the name GB-R LED or GB-r LED. Now, instead of a white LED, a combined blue and green LED coated with a red phosphor is used.

This technology allows you to get peaks in the spectrum in red, green and blue.

This technology is used today in LG on AH-IPS matrices and in Samsung on PLS. Using GB-r LED technology, you can achieve 99% Adobe RGB coverage.

Some manufacturers use a different method of magnification in their screens color range. They take a mixture of blue and red LEDs and use a green phosphor for the filter. This technology is called RB-LED or RB-G LED.