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 emissive technologies, where each pixel is a separate light source, in LCD models each pixel LCD matrices 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 backlighting 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 LEDs special form. Model data LCD TV ov is 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, 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 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. 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. In LED TVs with RGB backlight The LED lights up different areas of the screen depending on the color of the image. Colored backlighting provides enhanced contrast and deep blacks, as demonstrated by many Sony LED TVs.

Edge LED: Better Color Rendering

Sony in its new flagship TV models - 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: the color gamut of the Sony KDL-46W905A model is comparable to that of organic light-emitting diode (OLED) solutions and is unattainable 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, model 55EM9600 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, the USA and some European countries. The 55-inch model Samsung 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 their extremely fast response time, such devices allow you to simultaneously demonstrate two or four programs in the format high definition(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.

Quite recently - in the midst of summer, a report was published on our website Samsung LED TVs: from Kaluga with love, dedicated to the opening of the Russian Samsung plant for the production of various electronics and household appliances- Samsung Electronics Rus Kaluga (SERK). Let me remind you: key point the report was a story about the launch production lines for the production of the most modern and most relevant Samsung flat-panel TVs with LED backlighting today - the so-called LED TV. Since then, the editorial mail has received more than once letters in which our readers ask us to tell more about LED technology TV. The main questions lie in the technical details of the technology, its advantages over competing proposals, and so on. But almost always we are talking about the price factor: is it really worth paying for an LED TV an amount that is sometimes more than twice the cost of an LCD and plasma TVs with similar diagonals and screen resolution, will there be a real return on such costs? What is typical is that as time passes, the relevance of the questions asked does not decrease. Flat panel TVs are becoming fashionable, and their range is constantly expanding. You don’t have to look far for an example: the Kaluga plant of Samsung Electronics plans to produce about 75 thousand televisions of all three LED TV series - 6000, 7000 and 8000, with diagonals of 32, 37, 40, 46 and 55 inches by the end of the year and with special emphasis on the most popular are 32- and 40-inch models. Already now, these models are present on the shelves of most Russian retail chains, along with this, the choice of “LED” TV models from other companies is growing, so the growing interest in this technology is quite understandable. In short, today we publish short review features of the production technology of flat panel displays with LED backlighting.

LED TV or LED LCD TV?

To begin with, it is worth deciding on the terminology that has been established by now. The term LED TV, first introduced by Samsung Electronics and used by a number of companies, and various variations of this term like LED-backlit LCD, used by other companies, in practice means that we are talking about the good old flat-panel LCD screen, but equipped with a more modern and high-quality backlight – LED. In other words, to say that LED TV is exactly LED TV With technical point view would not be entirely correct. Various technologies where light-emitting diodes form the “picture” - such as OLED, OEL or AMOLED, belong to a slightly different class of displays. A real LED screen - where each pixel is displayed using one LED or a group of LEDs - can be found, for example, on huge billboards, looking at which from afar we see a whole picture, and not individual LEDs. Another example is Organic Light-Emitting Diode (OLED) displays, where certain types of organic polymer materials emit light when exposed to electric current. OLED technology is truly promising as a basis for the production of high-quality displays for TVs and monitors - such displays are lighter, do not require backlighting, have better color rendition, large range brightness, lower energy consumption, and in some versions even flexibility. Moreover, as technology improves, it is expected that over time the production of OLED displays will become even more profitable than the production of LCD screens. However, due to a number of technological limitations - for example, the lifespan of blue polymer phosphors, which is noticeably shorter than that of red and green organic LEDs, OLED technology is currently used mainly in the production of small diagonal screens for various mobile devices. Serially produced OLED TVs currently have a small diagonal; rather, they are rare exotics with a huge price rather than a mass product. Although, I repeat, the prospects for the technology are promising. So, let’s dwell on what the use of the term LED TV in practice means: we are talking about an LCD TV equipped with modern LED backlighting. In other words, it would be appropriate to label such TVs as LED LCD TV. However, in everyday life "with light hand“Samsung has nevertheless adopted a shorter and, apparently, more convenient marketing option - LED TV. Or LED-backlit LCD in other versions.

LED TV vs CCFL LCD TV

Everything is relative. Until recently, we used LCD TVs and monitors, most of them equipped with traditional backlighting based on so-called cold cathode fluorescent lamps (CCFL), in other words, fluorescent lamps. The production of screens using CCFL LCD technology has been “tested” on many generations of such devices and is currently relatively inexpensive, and the convenience compared to the previous generation of displays is cathode ray tubes, mainly such as lower weight and lower energy consumption, have led to the widespread (although not complete) displacement of the latter from everyday use. And everything would be fine, but illumination using fluorescent lamps has a number of disadvantages that can be considered fundamental. For example, with CCFL backlighting it is quite difficult to realize really deep black tones - constantly switched on lamps still create a certain “leakage” of light even in those parts of the image that, according to the idea, should be dark at the moment. This also logically implies a subjectively perceived decrease in picture clarity. In addition, fluorescent lighting makes it difficult to reproduce multiple colors, making it very difficult to achieve good color saturation. Among other problems of CCFL LCD technology, one cannot fail to note the difficulty in achieving high frequencies sweeps, limited period service life of lamps, relatively high energy consumption, and, finally, an environmental nuance - the need to use mercury in lamps. In a word, one way or another, the need to replace fluorescent lamps with something more efficient has matured a long time ago, and as a result of numerous experiments, the choice fell on LED backlighting. With its help you can improve at least four key factors image quality: brightness, contrast, image clarity and color gamut. Not to mention the more uniform nature of such illumination, which is important when viewing dimly lit scenes with initially low contrast. In addition to this, it is also worth mentioning that the efficiency of LEDs and longer operating time without loss of performance can significantly reduce the power consumption of LED TVs compared to conventional LCD TVs with CCFL LCD technology.

LED backlighting varies

To date, a number of different technologies for backlighting LCD screens using LEDs have been developed. As a rule, to create backlight modules (Back Light Unit, BLU), LED arrays composed of white or multi-colored RGB (Red, Green, Blue) LEDs are used. The backlight principle is also represented by two main options: direct (Direct) and edge (Edge). In the first case, it is an array of LEDs located behind the LCD panel. Another method that allows you to create ultra-thin displays is called Edge-LED and involves placing backlight LEDs around the perimeter of the inner frame of the panel, and uniform distribution of the backlight is carried out using a special diffuser panel located behind the LCD screen - as is done in mobile devices. Proponents of direct LED backlighting promise better results due to more LEDs and local dimming technology to reduce color casting. The reverse side of direct illumination - large quantity LEDs and the accompanying increase in energy consumption and price. In addition, you will have to forget about the ultra-thin design of the TV. Proponents of edge lighting, in addition to saving energy, promise no worse quality with a thinner design. Today, many global companies are producing LCD TVs with LED backlighting, including Samsung Electronics, Toshiba, Philips, LG Electronics, Sony and others. Each company uses variations of the above technologies in its LCD TVs and LED-backlit monitors. For example, Sony TVs use Edge technology LED, which made it possible to significantly reduce the thickness of fairly large TVs.

However, further we will look at LED TV technology using the example of Samsung Electronics TVs - for the reason that currently in Russia Samsung’s share of the LED TV market reaches 98%.

Samsung LED backlighting: how it works

At its core, an LCD screen is a multilayer “pie” made up of color filters, liquid crystal arrays, backlight lamps, etc. The liquid crystal cells themselves do not glow, but, depending on the voltage level applied to them, they open to allow light to pass through fully, partially open, or simply closed when a dark area of ​​the picture is displayed.

The role of the backlight lamps in this whole story is to illuminate the slightly opened LCD cells so that the final picture appears on the screen. Despite such a simplified retelling of the operating principle of the LCD display, this is quite enough to understand the purpose of its main components. The thickness of the layers of the “pie” of different LCD screens is different. When using traditional fluorescent lamps, the backlight layer is so thick that it occupies more volume than all other layers combined.

Let's replace the fluorescent lamps backlighting the LCD cells with LEDs. The first obvious effect of such a replacement is a significant reduction in the overall thickness of the LCD panel. Moreover, in Samsung LED TVs, the LEDs are placed not behind the matrix, but along its edges, due to which the presence of such an end layer has practically no effect on the overall thickness, but the overall weight is significantly reduced.

The LED BLU light-directing layer ensures uniform illumination in all areas of the screen. Thanks to a special reflective grille, the light transmission efficiency of Samsung LED TVs is stated to be 20% higher than that of models with direct RGB LED backlighting. In addition, instead of the usual 10 or more centimeters in thickness, it turns out to be less than 3 cm - if you want, put such a TV on a shelf, or if you want, hang it like a picture on the wall using a specially designed lightweight mounting system. The thickness of Samsung LED TVs 8000 series in the thinnest part of the body is 11 mm, in the thickest part – 29.9 mm. In advertising, Samsung always indicates the value obtained by measuring the thickest part of the case.

For reference: Samsung 8000 series LED TVs use 324 LEDs for backlighting. Thanks to the complete elimination of fluorescent lamps, LED TVs do not contain a single gram of mercury. IN Samsung technology In addition to this, it was also possible to completely get rid of soldering using lead compounds, and to practically reduce emissions of volatile organics and other harmful by-products by eliminating the use of sprayed powder paints - the thin, durable and attractive body of the new TVs is made using a special Crystal Design casting technology. Another significant advantage of LED TVs is the high level of image contrast, which significantly exceeds the best performance of traditional LCD matrices. The brightness of the LEDs is so high that, for example, in Samsung LED TVs of the 6000, 7000 and 8000 series, the contrast ratio reaches 1,000,000:1. In addition digital processing signal with Mega Dynamic Contrast technology provides a detailed image in low-contrast “twilight” areas of the picture.

The maximum capabilities of the new backlight system are squeezed out using a multi-layer Ultra Clear Panel filter, which transmits light from inside the screen and does not reflect it from the outside, so it is possible to achieve better brightness and contrast with a minimum of glare, regardless of how the screen is lit from the outside - sunlight or artificial electric lighting . LED backlight allows you to achieve white illumination of LCD cells, as a result of which it is possible to display a wider and more natural range of color shades. The color palette of LED TVs is richer and richer; the greens and blues of bright areas no longer look faded and pale compared to conventional models. In Samsung LED TVs, color saturation is also additionally monitored by the Wide Color Enhancer Pro hardware technology. Often weak point LCD screens cause blurred images with a long response time, which reduces the sharpness of the image and reduces the smoothness of the movement of objects in dynamic scenes. In the new Samsung LED TVs, this is monitored by the Motion Plus interpolation system: models of the 6000 and 7000 series have double the 100-Hz scan, and the flagship 8000 series have quadruple the 200 Hz scan.

An important factor is electricity consumption. Traditional LCD TVs are, of course, more economical than previous models with cathode ray picture tubes, but don’t forget that the diagonals are no longer the same, so with large LCD TVs, electricity meters still spin quite quickly. As for the new LED models, LED backlighting can significantly reduce energy consumption without sacrificing image brightness.

In addition to significant energy savings - up to 40% compared to traditional LCD models with the same diagonal, Samsung LED TVs They can also boast certification to one of the most stringent environmental standards, Energy Star 3.0.

LED TV Samsung: it's not just a TV...

Everything on a TV should be perfect - characteristics, appearance, and set of functions. Since we are talking today about specific Samsung LED TVs produced today in Kaluga, it would be an omission not to mention their main characteristics. This is only indirectly related to the topic of today’s article; however, I believe a few lines of details about the potential item of purchase will not be superfluous.

First of all, Samsung LED TVs of the 6000, 7000 and 8000 series, along with the reception of traditional analog channels ready to work with digital TV thanks to the presence of built-in DVB-T/C tuners. Whenever the era of ubiquity arrives digital television in Russia, you are already ready for this. In addition, the LNA plus tuner used in these models was created specifically taking into account Russian specifics - interference, vast open spaces and not the first freshness of television repeaters. In addition to this, thanks to the presence of two USB ports, the new TVs can be used as a photo frame for viewing photos from a flash drive, watching multimedia videos in DivX/Xvid formats, for example, from an external USB hard drive, and it will not be enough - there is a built-in 2 GB of flash memory with pre-installed flooded with content. The TV can be “registered” on a home network with access to laptops, desktops and external data storage devices, and the TV remote control turns into wireless keyboard to navigate through folders, display content from different places networks. For Internet access there is LAN connector and support for Internet@TV with access to YouTube. The sound system in ultra-thin LED TVs is on par with the best Samsung models. A unique flat subwoofer was created especially for ultra-thin LED TVs, plus well-proven hidden speakers are used.

Finally, communication with consumer electronics DVD player, Blu-ray player, AV receiver, cinema, HD video camera, game console, can be done using a connection via the HDMI interface, of which four are provided in the design of Samsung LED models.

LED TV: are there any disadvantages?

Yes, but what about: this is the price. So far, LED TVs are much more expensive than their traditionally backlit counterparts. However, the way out of such a price situation will be traditional: lower prices as demand grows and mass production increases. So far, the size of the LED TV market is small, but the interest in such models due to their outstanding characteristics is enormous all over the world. According to Display Search analysts, next year every fifth TV sold will be made using LED TV technology, and in a couple of years – every second. By this time we can expect prices to decline.

Hi all. Today we are repairing a Samsung UE32F5000AK with the “no matrix LED backlight” fault. I very rarely repair such TVs, since I have neither the equipment nor the amenities to repair such equipment. But nevertheless, this time I decided to try, and the owner of the TV really insisted.

So, let's begin.

Preliminary diagnostics of the TV

When you turn on the TV, there is sound, but no picture. The TV responds to the remote control and buttons. If you look closely, you can see that there is an image on the matrix, but there is no LED backlight. From this we can conclude that the backlight control driver itself is faulty, or some line of LEDs has burned out.

Disassembling the TV

Having decided on possible malfunction, started disassembling. Having placed the TV matrix on the table, the first thing I did was remove the stand, which is held on by three bolts. Next, I unscrewed the remaining 10 bolts around the perimeter, after which I was able to remove the back cover.

When removing the back cover, you need to keep an eye on the cable from the joystick, which needs to be disconnected, after which the cover can be set aside.

The TV consists of three boards, namely the power supply, on the board of which the backlight driver is assembled, on the left is the main board, and on the bottom is the t-con matrix control board.

Troubleshooting

In LED TVs, all LEDs are connected in series. This means that if any of the LEDs breaks, the entire LED backlight will stop working. As I said earlier, the main reasons There are two backlight faults: LEDdriver or LEDs.

If the driver is faulty, then for the most part, no voltage is supplied to the LEDs. If the line of LEDs is faulty, then a voltage of about 200 volts will flow to the power supply terminal, sometimes it can pulsate from 150 to 200. This indicates that the driver is trying to illuminate the backlight, but there is no load as LEDs, and the driver produces the maximum voltage. This is how I personally understand this process.

Having removed the power supply board, I determined that power to the LEDs is supplied through the D9101C to the capacitor, after which I decided to measure the voltage on it. Having connected the multimeter, it turned out that the voltage on it was in the range of 190-210V.

This means that the driver is running idle, and the problem is in the LED line itself. This was not very good news for me, since I am very reluctant to take on disassembling matrices due to my inexperience and lack of conditions for repairs.

Disassembling the LED LCD matrix

With the motto “do no harm,” I began disassembling the matrix. Having prepared the second table on which I will assemble the matrix, the first thing I did was disconnect the cable from the LCD panel to the T-con board. Having examined the structure of the TV in more detail, I saw that the matrix itself is supported by 2 frames, which are secured with latches. I removed the first frame from the beginning. To do this, I placed the TV on the back wall, and gradually, starting from the top, I began to unlatch the latches. I paid special attention to the bottom of the matrix so as not to damage the cables. The top frame came off very easily.

Next, holding the matrix, I placed the TV on the front, with the cables down.

Carefully removed the matrix boards (decoders) from the grooves so that they began to hang freely.

Matrix decoders removed from latches

I will say right away that this is such a painstaking process that my nerves were on edge. Having released the decoders from the latches, he took the TV by the second frame and carefully lifted it. The matrix remained lying on the table.

Removed matrix

Having removed the matrix to another table, he continued disassembling. Clicking the second frame, I removed the scattering film and got to the LEDs.

Under the LEDs there is a white reflector, which is held on by 4 locking clips.

After removing them, I was able to remove the reflector.

The structure of LED TV backlighting.

As you can see from the picture, the TV matrix consists of five LED lines of nine LEDs each. If we take into account that each LED is powered by approximately 3 volts, then we have that one line of LEDs uses about 27 volts (3 * 9 = 27). In order to check which LED has burned out, we first find in which line the LED broke. To do this, we alternately connect 27V power to the line of 9 LEDs, and whichever line doesn’t light up is the one that breaks. Next, we connect 3V power to each LED one by one, and look for which LED is not lit.

In my case, it turned out to be very easy to identify a burnt-out LED, since it got very hot, as a result of which the diffusing lens on it changed color and got a little straighter.

The temperature was such that the textolite with reverse side also burned out.

Having pulled out the lens, the LED fell out. For this I used a soldering gun. I applied flux on top of the LED and heated the board from below until it was unsoldered. So I decided to solder the new one too.

Finding a new LED is another task. After going through the radio market several times, I found similar LEDs in one of the stores, albeit already soldered. The man unsoldered them from the TV, on which the matrix was broken.

I also soldered the LED using a soldering gun. Having tinned the tracks, I placed the LED on it with the required polarity, and slowly heated the PCB from below until the LED was soldered. It didn't seal very nicely, as the white paint peeled off, but it was secure.

Every person, when choosing a TV for themselves, learns about the latest achievements of science, gets acquainted with new technologies and terms. One of the modern technologies in the field of television is LED. In reality, an LED TV is an ordinary liquid crystal LCD TV. This means that the image in it is formed using a matrix consisting of pixels.

If in older devices the backlight was a fluorescent lamp, then in LED models the backlight is a matrix consisting of a set of LEDs (Light Emitting Diode).

Light Emitting Diode is translated as “light emitting diode”. The scope of their application is extensive: these are car headlights, traffic lights, lamps, spotlights, street and home lamps. In a TV, light from LEDs is directed onto the LCD screen, illuminating the image.

Of course, it would be more logical to call these models LCD TVs with LED backlighting. However, Samsung, which is a pioneer in this field, called these models "LED TV". The term became popular and began to denote a class of new televisions. The LEDs in these TV receivers do not form a picture as a real unit (pixel). Therefore, LED TVs cannot be considered full-fledged LED models.

How LED lighting works

To understand the operating principles and features of this device, you need to become familiar with the types of backlighting on a TV. Currently, several lighting systems have been developed. They differ from each other in their location and color.

Color of glow sources

Single color system (White led) more energy efficient than fluorescent lamps, but is still considered a budget option. LEDs do not contain mercury, like lamps, but in terms of color rendering and coverage depth, LED TVs with this backlight are practically no different from LCDs.

Multi-color system (RGB) compares favorably with the previous version. TVs with this backlight have a wide color palette. Accordingly, very good color rendition. Unfortunately, this effect comes at a higher price. To operate such models, you need a modern, powerful GPU. These TVs consume more electricity and have a more bulky body, comparatively speaking, of course. The cost of these TVs limits demand, so leading companies are gradually abandoning RGB backlighting and are looking towards analog household appliances.

Mixed backlight option (QD VIsion) uses LEDs only of blue color and special films. The film is a collection of quantum dots that have red and green colors. This allows you to have a tuned spectrum of optical waves, limited in range. For this account color palette expands and brightness and intensity improves. Unlike the RGB system, this technology is more energy efficient.

The answer to the question of which backlight option to use is ambiguous. There are still various controversial opinions and discussions on this matter. Toshiba believes that white backlight in terms of the totality of all characteristics, it is preferable to RGB.

Accommodation options

There are two options for placing the backlight:

General advantages of LED TVs

These devices are an undoubted step forward in the development of television. They enjoy deserved popularity in everyday life. There are several main advantages:

Manufacturers are constantly working to improve these panels. The new technology is called OLED TV. In these TVs, the backlight is organized using organic light-emitting diodes. They are characterized by an even thinner body and improved color rendering.

Speaking about LED technologies, we should not forget that in the manufacture of LED TVs they do not use, as before, harmful substances - mercury and aerosols.

Some LED-TV models use “local dimming” technology. It is designed for local dimming. The basic idea is to control groups of LEDs. Each group contains several elements. True, with such an approach separate areas bright spots sometimes appear on the screen in areas where the backlight is turned on full power. And where the backlight is not used, dark spots may appear.

Screen resolution. Determined by the number of pixels that form the image in width and height. The higher this parameter, the clearer the image and the more different details you can see on the screen.

LED-TV mainly have Full resolution H.D. (1980x1920 pixels) and H.D. Ready (1366x768 pixels). These are the most popular video formats in currently. Some premium models have 4K UHD resolution (3840x2160 pixels).

Almost all 4K UHD TVs support HDR. This is an extended dynamic range format that allows you to depict a picture as close to reality as possible.

Screen coating. There are matte and glossy. With a matte finish, the image is softer. The viewing angle is limited. There is no glare when exposed to sunlight. If the coating is glossy, then the picture on the screen is very bright and contrasting. Visibility becomes poorer in bright sunlight.

Functional connectors. Usually there are standard ones: HDMI output, Ethernet output and USB connector for watching video from a flash drive or hard drive. The latest models have a D-sub video port. It involves connecting a computer to a TV.

Sweep frequency. An indicator of how many frames of a film are shown per second. It is measured in Hertz and can reach values ​​up to 960 Hz. For 3D TVs, the frequency can be even higher. The recommended range of values ​​so that the image does not blur and pictures do not overlap one another is 100−200 Hz.

Additional features

DVB-T. Digital television standard. Allows, in addition to analog cable and terrestrial television, connect satellite.

Volumetric 3D image. Using this option, you can view 3D images with active or passive 3D. It is necessary to take care of special glasses.

Smart TV. Allows you to connect and use the Internet. The connection occurs via the WiFi module. Connection possible via network cable. Some TVs allow you to build in an additional router. With Smart T.V. you can play videos from the Internet, play, listen to music, and search for information.

LED devices have become popular. After all, LED TV - what does it mean? This high quality, convenience and comfort of use. The advantage of an LCD TV is LED backlighting; all LED models have it. But for design features, additional features sometimes have to be paid extra. What should you pay attention to when choosing an LED TV model?

First of all, you need to decide which diagonal is best to choose. The stores offer a huge selection of different models from 19 to 58 inches. Sometimes it is not very common to calculate in inches and you have to select the size in centimeters, that is, from 48 to 147 cm. The correct choice of diagonal depends on the size of the room where the TV will be installed.

There is an approximate table of the ratio of diagonal and distance to comfortable viewing.

These data are approximate and allow adjustments within half a meter.

• 14−17 inches - from 1.5 to 2 m.
• 21−25 inches - from 2 to 3 m.
• 26−32 inches - from 3 to 4 m.
• 34−37 inches - from 4 to 5 m.
• 42−55 inches - from 5 to 7 m.
• 61−80 inches - from 7 to 10 m.

So, when choosing a TV, you need to think about its location in the room in advance and choose the optimal model based on the layout.

After choosing the TV diagonal, you need to consider the resolution. Here the criterion is the larger the better. Full HD will provide complete comfort and satisfaction from your TV.

The quality of the picture is assessed subjectively. If possible, colors should be natural, without overexposed areas or spots. The image during fast movement should not be jerky, but smooth. The black color must be free of impurities, as black as possible. You should check the transmission of halftones to see if the details are different. The color of the human body: hands, face should be pleasant, without yellow or red spots.

Manufacturers need to be well-known. In addition to the guarantee, this also includes service, as well as the availability of various additional parts and accessories in stores and service centers.

And of course you need to think about additional functions. Do you need Internet access or how important is it to connect your laptop to a large screen?

What is the difference between an LCD and an LED TV?

LED technologies are gradually replacing liquid crystal technologies, since the former are more efficient and economical. This is a serious energy saving and best picture on the screen. Although the differences between these LCD and LED approaches lie only in the way the screen itself is illuminated.

Everything is moving forward. Modern films are produced for latest technologies. Therefore, in order to fully immerse yourself in the atmosphere of the new film, it is better to watch it on LED-TV.

Today, devices with LED backlighting are the best solution in terms of image quality and equipment cost. Modern solutions in TVs of this type make it possible to compete with expensive plasmas (PDP), confidently displacing the latter from the market.

True OLED TVs are very promising. In these panels, LEDs are truly the imaging unit. But these models are still expensive and only pay for themselves with very large screen sizes.

Attention, TODAY only!

funny barbel August 8, 2012 at 11:52 pm

We make bright and economical LED lighting from broken LED matrices(how to make the matrix backlight work without a laptop)

• Lumber room *

Hi all. I decided to write another post in the sandbox (possibly the last one, it’s starting to seem to me that such topics are not welcome here) and again on the DIY topic in which I want to submit interesting idea, but decide for yourself how to use it. Nowadays, the vast majority of monitors and laptops are equipped with ice-backlit screens (I think few people were surprised when I said this). Often the matrices are broken, and after such repairs I usually end up with a chipped matrix that cannot be restored. We will talk about how to use LEDs and a matrix board to power them.

Of course, you can leave it as a donor, but time has shown that matrices with diode backlighting die extremely rarely (for me, they usually wear broken ones). And the idea came to mind to use a line of diodes with a standard feeder for my own purposes.

Pros - a fairly bright light source, in theory quite economical (due to the converter), stable brightness, durability, wide range supply voltage (usually from 8 to 19 volts), disadvantages - large electronics board (can be overcome in part, more on that below), perhaps for some - the need to solder. What is a backlight module? This is a line with diodes on which several chains of LEDs connected in series are placed.

And the converter chip itself, located on the matrix board, to which supply voltage and two control signals are supplied - one to turn on the backlight, the second to control its brightness. To turn on the backlight, we will supply power (10-19 volts) and connect the backlight and brightness control pins together and apply 3.3 volts to them. The pinout of the connector is given below. The authorship of this picture belongs to a person from the site rom.by (by the way, all other images are mine and made specifically for this article, but I decided to take the finished one and not redraw it).

We take the common wire from the GND contact, supply power to the LEDVDD and connect inwt_pwm and dispoff# together and supply three volts to them.
We also need a stabilizer to obtain 3.3 volts. In the simplest case, it can be the diagram below. To calculate the resistor, the formula is R = (Usupply-Uzener diode)/Izener diode. We take the average current and the average expected supply voltage. That is, for example, we take an average power supply of 15 volts, a zener diode of 3.3 volts with a stabilization current of 10 mA and we get 1.1 k.
I believe that computer scientists not related to electronics may have problems finding a zener diode - it can be replaced with a TL431 + any low-power silicon diode (in the example 1N4148). Both can be torn out of a dead ATX power supply from a PC. Both circuits are given below. The capacitor, in principle, is almost any 1-10 uF. for the second option with tl431, you can not count but take a resistor in the region of 2-3k, and everything works stably. I think that it is even easier to assemble using the second circuit. The circuits are presented below. inwt_pwm and dispoff# in the circuits correspond to PWM and LED_EN, respectively.

The backlight has been launched and you can come up with a use.

But as many will probably rightly note, we have a very inconvenient large board of which we can only use a small part. Unfortunately, here I can only give general advice- call the contacts from the connector to the elements next to the backlight chip, solder the wires to them, make sure that everything works and cut off most of the board hoping for your luck. By the way, let me add that the LEDVDD power supply usually comes to the fuse standing nearby with a converter and a connector for connecting LEDs, it is usually designated F1 / F2. But control signals can be output to contact pads next to each other and labeled as desired or even present only on the legs of the elements.

And finally, a photo of what I got. Photos turned off and on were taken at the same time, the photo was taken automatically, the light is very bright and therefore the photo turned on turned out to be with a dark background.

AND close-up photo of reworking another board. Here I filmed it with my phone - it turned out better.

I will say that I have already tried about 15 boards. One flatly refused to start (it’s possible, of course, that it’s faulty, but I’m mentioning it just in case). The rest started up, two suffered from the fact that I cut the board too short (apparently there were some critical circuits in the inner layers that got into the cut area) and after cutting off the “extra” part they stopped working. For the sake of experiment, I also tried to supply full power to the matrix instead of 3 volts to the control pins in order to reduce labor costs. We took 5 test subjects - two boards failed immediately, two more after a day and a half, one works. Therefore, I abandoned this idea and in all subsequent ones I feed the control conclusions as described above. The article does not discuss controlling the brightness of the backlight - there was no such need yet, so I left it for later.

Application is limited only by imagination - you can make a backlight in the workplace, use it for modding in a system unit, as a backlight in a car and a lot of other things. Well, if anyone has any questions, I will try to advise.

Tags: D.I.Y, LEDs, led, lighting, matrix