How does LCD and LED TV works?

Update - 2017.03.22

LCD and LED TV works

The common questions before buying an LCD or LED television may be “How does LCD and LED TV works

Before comparison, the first question: What’s a LCD and LED TV?
The first, LCD TV backlighting is a complex subject, and the marketing of different TVs to make …

How does LCD and LED TV works?

How does LCD and LED TV works?

The Basics: LCD TVs and so-called LED TVs work by blocking light. By sandwiching a solution of TN liquid crystals between two perpendicularly aligned panes of polarized glass, it becomes possible to manipulate the intensity of light as it passes through this crystalline matrix and out the glass panel at the other end.

In other words, LED TV is a variation of the LCD, or liquid crystal display, television that utilizes light-emitting diodes for its backlight in place of the standard cold cathode fluorescent lamps. It was formerly referred to as an LED-backlight LCD TV.

LED technology produces improved contrast ratios on screen because LEDs yield deeper blacks and emit sharper images. It also provides better viewing angles than the previous LCD screens and requires less power to operate.

LEDs last longer than fluorescent lights, so these televisions can remain in use longer. Televisions with edge-LED lighting systems are slimmer and more space-efficient. In 2005, Sony was the first to introduce LED TVs to the public.

Depending on the voltage of the electrical charge running through them, liquid crystals will untwist so that the intensity of light able to pass through the second polarized panel is affected.

Basically, these displays can switch between light states (where the liquid crystals are fully twisted) and dark states (where the liquid crystals are fully untwisted), or somewhere along the grayscale in between. The term “liquid” in liquid crystals is actually a misnomer as they are not a fluid substance but rather a hard crystal.

How does LCD and LED TV works?

How does LCD and LED TV works?

Addressing: A liquid crystal display consists of an array of tiny segments-called “pixels”-that are manipulated to form images or to present information. Addressing is the process by which pixels are turned on (which disables the passage of light) and off (which enables the passage of light) so as to create an image on the polarized display panel in front of you.

So-called active matrix LCD TVs employ thin film transistors (TFTs), or tiny switching transistors and capacitors arranged in a matrix on a glass substrate, to direct electric charges down columns to reach a particular pixel. This, in turn, causes the liquid crystals to untwist and “display” a predetermined amount of light generated by the light source usually a fluorescent bulb in the back of them.

Color (Re) Production: The light source in an active-matrix LCD TV is a series of fluorescent bulbs (called CFL or CCFL), or the more newly implemented LED (light emitting diode) backlighting (LED TVs) both of which emits white light through a polarized glass pane behind the liquid crystal solution.

Theoretically, then, you can start with a white display: This is one where its liquid crystals are completely twisted and therefore able to direct the full spectrum of light out through the polarized display screen in front of you. Since all wavelengths can pass through, the full spectrum of light can be manipulated to create the desired color.

To achieve a full-color pallet on your LCD or LED TV, each pixel is divided into three subpixels-red, green, and blue that work in conjunction to determine the LCD pixel’s overall hue. These subpixels are created by subtracting certain wavelengths, and the color(s) corresponding thereto, using special filters.

By exploiting a combination of red, green, and blue subpixels of various intensities (or gray scales), a single pixel triad can reproduce approximately 16.8 million colors. Recently, Sharp Electronics has introduced the new Quattron Quad pixel technology which introduces a 4th color pixel – yellow. This increases the number of possible colors 4 fold.

Some cheap LED TV available on amazon:

Manual
Liquid Crystals

Liquid Crystals

Princeton University Press. 2017

Liquid crystals are a phase of matter critical both in many recent scientific developments in biology, chemistry, and physics and in applications such as computer displays, electronic books, and new thermometers. This fully illustrated book builds on basic scientific concepts from biology, chemistry, and physics to explore the full range of the broad and interdisciplinary field of liquid crystal science. After a brief introduction to liquid crystals, the text sketches the history of research...

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