LED is not a separate type of display, but one of the types of LCD backlight, that is, under an LED TV It means a monitor using liquid crystals (LCD TV, liquid crystal), which has the type LED backlight. What is a similar technology, we will examine further.
- What is this technology?
- How is it different from other technologies?
- Types of LED backlights
- How to choose an LED TV?
- Video: how is the LED TV?
What is this technology?
The acronym LED stands for “light-emitting diode”, which means “light emitting diode” or simply “LED”. 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 introduction began relatively recently.
The technology is implemented according to the following principle: behind the main screen that the viewer sees, there are point light sources - LEDs. The light emitted by them passes through the screen, undergoing certain transformations along the way, and thus the final image is formed. What a similar backlight system looks like, can be seen in the photo:
LED technology allows you to achieve the most profitable at the moment the ratio of costs to the quality of the generated video, and therefore is actively used by modern manufacturers.
How is it different from other technologies?
In order to accurately identify the primary qualities and features of LEDs, it is worth comparing it with other ways to create moving pictures.
It stands for "liquid-crystal display" and means that for the backlight of the screen from the back light sources are used, but ordinary fluorescent lamps are used in their quality (fluorescent). The service life of such lamps is relatively small, and the brightness decreases significantly over time. In addition, in their manufacture very harmful chemicals are used - mercury compounds.
The brightness of conventional LCD displays is low. The fact is that the light on the way from the lamps to the viewer passes through several layers of diffusers and rotating cells of liquid crystals. At the same time, a clear black color is not displayed, because part of the light still "seeps" through the closed crystals. The dimensions of the lamps are quite large, so such screens cannot be ultra-thin. But LED is the direct descendant of the LCD, so there are not so many fundamental differences.
Plasma TVs, by contrast, use a completely different method of creating images. Unlike LEDs, they generally do not need artificial backlighting - each pixel on the screen itself emits light. Due to this, the brightness of the image of plasma panels is beyond competition, and they are often installed on the street. However, energy consumption is the same high when compared with other competitors.
Cells have the ability to quickly fade, that is, lose brightness with constant operation. And the constant presence of the same icon of the channel in the corner of the screen will burn the cells involved, which will be noticeable when switching the channel.
Means "organic LED". The technology is based on organic LEDs. In this case, the word "organic" means not LEDs from living tissue, but semiconductor chemical compounds - polymers containing carbon.
Compared to LED, 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 many problems - they are very sensitive to air humidity, LEDs blue color quickly enough (for a couple of years) lose their luminosity, the screen life directly depends on brightness. The price also remains high.
Not so long ago, Samsung announced the QLED technology. This abbreviation stands for "quantum LED" ("quantum LEDs"). Each subpixel on the screen is not a color filter (one of three colors), but a full-fledged blue LED, and red and green colors are generated by the so-called "quantum dots" - areas on the screen that, when light falls on them, themselves begin to emit shine. Blue light falls on them from the back side, and they themselves emit red and green colors towards the viewer.
So far, such screens are quite expensive and rarely found, but they have a lot of advantages, including a long one. service life, scanty power consumption, low cost and low price of the transition to a new type equipment. They also change shape very easily, so they are the best candidates for the role of the imaging surface of flexible tablets.
Types of LED backlights
There are several common types of LED-backlights that are used in the manufacture of LCD TVs.
Literally translated as edge or face. In this case, we mean that the LEDs are located around the perimeter of the rear of the case. It 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 on the side of the image makes the case exceptionally thin.
Direct means direct or direct. With this embodiment, the LEDs form a kind of the matrixevenly distributed on the back surface. This provides extremely precise control over the brightness at each point in the image, but at the same time does not allow the manufacture of ultra-thin cases. The difference from the previous type can be clearly 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.
This is a combined technology, where “W” means “white”, that is, in addition to color, a fourth, white, LED is also used. Such a trick, if necessary, makes the image brighter, and energy consumption due to reduced load on the color LEDs, on the contrary, is less. This technology is promoted by LG.
How to choose an LED TV?
LED TVs are the undisputed leaders in terms of sales and price-quality ratio, therefore, you can make your choice from the most popular models of screens with a similar backlight and a diagonal of 42 inches.
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 the color scheme there are not only traditional colors (red, blue and green), but also additional yellow, which makes the image more in kind. This is an exclusive feature from Sharp.
Frame rate - 200 Hz, a digital tuner for all popular formats, LAN over Wi-Fi and twisted pair (and support for Skype, only the camera will have to be purchased separately). You can watch videos in MKV format, although not all kinds. A flash drive or external HDD must be formatted for FAT or NTFS, but the Blu-ray or DVD format is not supported. There is an option Time Shift - recording on a USB flash drive or USB-drive with a delayed viewing.
The only drawback is that the processor sometimes does not cope with complex color transitions correctly, which is not a problem for dynamic scenes.
An interesting model in which there is no Smart TV function, but there is also a built-in browser, and YouTube, and Skype (a proprietary camera with a built-in microphone must be purchased separately). The device is equipped with sensors, one of which assesses the level of illumination and automatically adjusts the brightness, and another detects the absence of spectators and also automatically de-energizes the device after a certain period time. The built-in player has limited functionality.
There are simply no direct flaws on the TV, although there is a feature: when the dynamic mode is on Brightness seems superfluous, but when you turn off the speakers, scenes with low lighting.
This model is the cheapest representative of the 3D Cinema family. The horizontal rows of pixels on the screen emit polarized light — even for the right eye and odd for the left. Such an image is normally perceived by the naked eye, and at the same time creates a 3D effect when using branded light glasses with passive polarizers. In this case, the image does not flicker and does not 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 in fact the picture is created through a line;
- suboptimal contrast.
The built-in intelligent brightness control system is designed to smooth out this barely noticeable flaw.
The TV is equipped with a player that easily reproduces the MKV format and digital broadcast standards.
PANASONIC VIERA TX-LR42U3
Integration into the world of modern communication technologies is not the most impressive: Skype is not available, a USB camcorder or you can’t connect the keyboard either, although it’s possible to access weather and news sites thanks to the Viera service connect. There is no 3D mode at all.
These shortcomings are commented on by the quality that is the best of all the models proposed 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 of "frame insertion", designed to eliminate blurry and flickering images.
The most affordable instance of a number of models designed to watch 3D movies through special “shutter” glasses. It is assumed that the consumer either already has such glasses, or he can easily buy them separately. This is a legitimate marketing move.
The hardware is quite modern:
- digital tuner for analog and digital TV popular formats;
- a 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 from external media, that is, flash drives and mapped drives. Used proprietary image optimization algorithms form an amazing picture without blur, areas with obscure colors and other artifacts. This becomes especially noticeable when watching videos of “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 a recording with one touch, mark the necessary moments (to instantly return to them), and so on.
Video: how is the LED TV?
In the short video below, the wizard parses the Samsung LED TV and shows how it works:
So, LCD TVs with LED technology are very popular, because they represent the best value for money. The variety of such screens is amazing, everyone can choose tv with optimal functions for yourself, for example, SMART, Wi-Fi, satellite tuner or webcam.
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