The device working principle of LED TV

Recently I was asked what is the difference between LCD and LED? Answer: both those, and others (LCD and LED) are LCD (televisions with liquid crystal display). Structurally, LED TV differ from LCD TVs the only way backlight LCD display (or matrix, as it is easier): instead of lamps are light emitting diodes. Well, the article is finished, go to beer bnap

Okay, okay, there is something to tell about the history of LCD TVs ad let's Start with the very definition of abbreviations: LED TV (abbr. from the Light Emitting Diode TeleVision (led TV. Actually, to be honest, it looks like this:

LED TV

It really is LED or led screens (panels), You often can see them on main streets of the city, in football stadiums or concerts. Their main drawback - "grain", which is due to the size of the LEDs. To make an led as small as a pixel on the LCD matrix is not, but, from a distance, the graininess is not noticeable, and the modular design allows you to collect (like the blocks) is just huge screens:

Led screens

However, we already used that LED TV is something quite different, namely an LCD TV, the backlight of the screen which is an led matrix (LED). Such a term as LED TV was introduced by the Corporation Samsung 2007 year to promote its own line of LCD TVs, the backlight which was not done by lamps, and LEDs. If you look superficially - "LED is thinner than LCD, but the image quality was much better

the LED is thinner than LCD

Types of backlit display: Edge LED and Direct LED
Let us look at the types of led backlight display. First of all, it is direct - Direct LED and end - Edge LED. Want to know more?, then I recommend to read another small article: Edge LED and Direct LED.

When direct Direct LED or backlit, the LEDs are arranged over the entire area of the matrix, evenly lighting through the diffuser:

Screen back-lit

The thickness of LED TV is reduced, but not by much, compared to LCD TV, which applied lamp lights. Here is the matrix with bright white LEDs:

Led matrix

end or lateral illumination of Edge LED has its pros and cons. Consider the principle of operation of the mechanical matrix illumination: LEDs are located at the top and bottom, the sides or around the perimeter of the matrix, the light from them through the special svetorasseyaniya, gets on the lens, and then the screen

end of the led backlight

In this figure you can see why TV is back-illuminated Direct LED cannot be as thin as when side lighting: no lights, no LEDs, not closely pressed to the lens distance required for dispersion of the light flow bk Due to mechanical arrangement, the LEDs do not take up space behind the lens, therefore, this design allows to considerably reduce the thickness of the matrix and all of the TV.

Side-illumination

end Edge-lit LED more efficient (use fewer LEDs), but also shines worse (for this reason) the Second serious drawback - highlights. At minimum panel thickness, to obtain a perfect distribution is very difficult, the thin lens can not cope with this task, as a result, dark portions of the matrix (without signal, for example) can observe the light spots (glare) that interfere with the comfortable perception of the image screen of such a TV

end illumination and glare

So far, we talked about static (that is, continuous, permanent) lighting, it is time to consider dynamic ab Main difference dynamic backlight static that the LEDs are off permanently it all depends on the image. Led matrix is divided into groups, each of which is controllable, such control can adjust the brightness of the LEDs of each group, ensuring a more precise colour reproduction and deep black color" bs

Static and dynamic backlight

The last type of illumination, which we now consider, is dynamic RGB video and side (end) lights. In this type of backlighting use LEDs of the primary colors: red, green and blue, and, sometimes, even and white (the best colour)

Dynamic RGB video lighting

The diodes can be placed "one by one" or that such assemblies, when in a single housing located sweetparadise elements of all the basic colors:

Combo led

Such a matrix can not only "highlight" different areas of the image with a given brightness, but also to provide the "illumination" needed color scheme, with the result that the image is obtained as "right", clear and beautiful ay

the Matrix with a dynamic backlight

end dynamic backlight, though, and "saves" the thickness of the matrix, but does not give such effect, as can "highlight" only the overall picture (they'll Shine a matrix on the entire length or width), so I think it is better to leave this type of lighting for external effects that will perfectly complement the overall picture

end dynamic backlight

to Summarize:
- LED is thinner, especially when using lateral illumination, but there is a danger of "spotting"
LEDs have lower power consumption and do not contain mercury (unlike bulbs)
led lamps last longer (theoretically, time will soon show)
- LED TV brightness, contrast and clarity higher than the LCD (or LCD matrix with lamp backlight)
- due to the dynamic lighting is achieved in the most proper and saturated color reproduction

OLED TV

conclusion:
OLED TV - in this technology based on the use of OLEDs, such a thing as a "backlight" is non-existent, since the diodes are of basic colors that form the image directly on the screen and illuminate themselves, in addition, this TV will be in a tube collapse, but this is another story ab

Link to this story: http://en.rem-tv.net/publ/3-1-0-38

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