LED Backlight
2009-07-23
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Explanation guidance on LED Backlight
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The LEDs are conquering the world. So far bulbs and fluorescent tubes were the kings of the lighting but that is ending, with the market gaining LED flashlights, car headlights and now LCD-TFT screens.

LCD-TFT screens do not emit light, requiring several high-powered lights on the rear panel to get to the necessary brightness to the image. For this purpose white fluorescent lamps.
Currently, the most commonly used device to emit a fluorescent light is called a cold cathode tube or CCFL.
The CCFL is called cold cathode tube because, unlike
the cathode ray tube, this light does not require preheating
filaments.
Are already close to going to market the first screens backlit by LEDs.

The advances in lighting have succeeded in creating high-power diodes and low power consumption, capable of emitting bright white light. Using these diode liquid crystal displays (LCD-TFT) consume much less power, emit less heat, life is much higher (it is rare for an LED stop working) and also get a wider color gamut (color range ) and less variability of the lighting on the panel. This same technology can be used in projectors and overhead projectors, being able to remove the cooling system, which will make these devices more noise and lightweight.

This technology is sure to be an intermediate step before the arrival of OLED TVs, which overcome the limitations of the TFT and also emit their own light, requiring no backlight.
Sony has been one of the promoters of this technology, which used high-end monitors and computer screens ultraportables.
Sony gives us graphically what is really inside of a Sony LCD TV, citing its BRAVIA X4500, ZX1 yWE5. In these computer graphics we see the difference with backlit LCD technologies HCFL, Edge LED backlight and LED backlight, as well as improvements posed against most current LCDs.
Backlit LCD TV HCFL
1. Backlight
HCFL: The backlight uses HCFL WE5
(Hot Cathode Fluorescent Lamp). Most TVs use
Backlight CCFL (Cold Cathode Fluorescent) that consumes twice
energy.
2. Diffusers:
to ensure uniform brightness across the LCD panel.
3. Polarizers:
The two polarizers in front and behind the LCD panel ensures that the
produced image is aligned properly.
4. LCD (Liquid
Crystal Display): A LCD panel consists of millions of
filled with liquid crystal pixels arranged in a grid, which
open and close to let in light and create images.
5. Layer
beam: Sony anti-glare layer provides a
mirror finish that makes the light brighter.
6. Screen.
LCD TV with LED backlight
1. Backlight
LED: The BRAVIA X4500 uses
Backlight LED (Light Emitting Diode) RGB (red, green, blue). The
LEDs for red, green and blue colors create intense, pure and realistic
The white LEDs used by other brands, although there are fewer
models that use white LEDs.
2. Diffusers
3. Polarizers
4. LCD Panel
5. Layer
antiglare
6. Display
LCD TV with LED backlight Edge
1. Backlight
LED Edge: The BRAVIA ZX1 uses LEDs located
along the frame of the TV to get a much thinner design.
In particular, the ZX1 measures just 9.9mm at its thinnest.
2. Guide plate
light: works to focus light evenly, getting
a brighter image.
3. Diffusers
4. Polarizers
5. LCD Panel
6. Anti-glare coating
7. Display
Alongside all this is true that fluorescent tubes were constantly
on, was really difficult for blacks to be really
black (it was rather dark and light gray).
However,
LED technology, whether white or colored, turn on and off so
controlled by improving the contrast between light and dark areas
the image, while allowing to reduce the thickness of the screen and
energy consumption (if the image of that pixel or group of pixels is
black light bulbs go off, while the long fluorescent
were on). A good example is the new series XS1E
Sharp LCD TVs which feature more than 1,000 LED segments
working independently according to the color and lighting
predominates in your area.
Hopefully with the LED technology neva better yet something else the issue of blacks, as it has never achieved perfection.
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