What is LCD?
LCD is a flat display technology, stands for "Liquid Crystal Display," which is generally used in computer monitors, instrument panels, cell phones, digital cameras, TVs, laptops, tablets, and calculators. It is a thin display device that offers support for large resolutions and better picture quality. The older CRT display technology has replaced by LCDs, and new display technologies like OLEDs have started to replace LCDs. An LCD display is most commonly found with Dell laptop computers and is available as an active-matrix, passive-matrix, or dual-scan display. The picture is an example of an LCD computer monitor.
The LCD displays are not only different in terms of heavy than CRT monitors; even the process of working of them is also different. An LCD contains a backlight rather than the firing electrons at a glass screen, which offers light to individual pixels arranged in a rectangular grid. All pixels have a sub-pixel, red, green, and blue, which can be turned on or off. The display appears black if all of a pixel's sub-pixels are turned off and appears white if all the sub-pixels are turned on 100%. The millions of color combinations can be possible with the help of adjusting the individual levels of red, green, and blue light.
As compared to CRT technology, LCD consumed much less power and allowed displays to be much thinner that also made them very less heavy. Instead of emitting light, LCDs work on the principle of blocking light. In an LCD, where an LED ejects light, the liquid crystals produce a picture with the help of using a backlight. Also, while comparing with gas-display and LED displays, LCDs consume less energy.
The CRT monitors and TVs have a refresh rate, but LCD screens do not have a refresh rate. If you feel a problem with eye strain with the CRT monitor, you might need to change the monitor's refresh rate setting on your CRT screen. But with the new LCD screen, you do not need to adjust the refresh rate setting. Some LCD computer monitors provide support for VGA cables, and most have a connection for HDMI and DVI cables. But offering support for VGA cables is much less common.
Different Types of LCD
There are various kinds of LCD, which are discussed below:
How LCDs Work?
The principle behind the LCDs is that for switching pixels on and off to reveal a specific color, LCD screens use liquid crystals. And, the molecule tends to untwist at the time of electrical current is applied to the liquid crystal molecule. This becomes the reason for a change in the angle of the top polarizing filter as well causes the angle of light, a light that is passing through the molecule of the polarized glass. Consequently, with the help of an individual area of the LCD, a small light is allowed to permit the polarized glass.
Thus, as compared to other areas, this particular area will become dark. Instead of emitting light, LCDs work on the principle of blocking light. A reflected mirror is arranged at the backside at the time of constructing the LCDs. An indium-tin-oxide is used to make the electrode plane, which is kept on top of the device. Also, on the bottom of the device, a polarized glass with a polarizing film is added. With the help of a common electrode, the LCD's complete area has to be enclosed, and the liquid crystal matter should be above it.
Then comes another polarizing film on top, and on the bottom, in the form of rectangle, the second piece of glass comes with an electrode. But make sure that both pieces are located on the right angles. The light passes through the front of the LCD when there is no current, reflecting with the help of a mirror and bounced back. A screen is in front of the light that is made up of pixels colored red, green, and blue. In order to reveal a certain color or keep that pixel black, the liquid crystals work for turning a filter on or off. This is the reason; the LCD monitors and TVs consume much less power as compared to CRT monitors or televisions.
History of LCD
In 1888, Friedrich Reinitzer, chemist and Austrian botanist, discovered the first liquid crystals in cholesterol extracted from carrots.
In 1962, with the help of the application of a voltage, stripe patterns in a tinny layer of liquid crystal material were generated by RCA researcher Richard Williams. This impact is depending upon an electrohydrodynamic instability forming inside the liquid crystal that is currently known as "Williams domains."
According to the IEEE, a method for electronic control of light was planned by George Heilmeier with Louis Zanoni and Lucian Barton led by a team of engineers and scientists at the RCA David Sarnoff Research Center in Princeton, New Jersey, in the mid of 1964 and 1968. And, they demonstrated the liquid crystal display for the first time.
Additionally, a global industry was launched by their work that now produces millions of LCDs. He used Heilmeier's liquid crystal displays as dynamic scattering method (DSM), in which an electrical charge is implemented to scatter light by rearranging the molecules. The dynamic scattering method was proved to be consumed high power and worked badly. Hence, an improved version of DSM replaced the older one. And, in 1969, James Fergason invented the twisted nematic field effect of liquid crystals, which was used by this improved version.
In the early 1970s, in liquid crystal displays filed, James Fergason is hold some of the fundamental patents. Also, for "Display Devices Utilizing Liquid Crystal Light Modulation, he holds a key US patent number 3,731,986. Later in 1972, the first modern LCD watch based on James Fergason's patent was produced by the ILIXCO, International Liquid Crystal Company owned by inventor James Fergason.
Advantages of LCD
LCD panels are increasingly rapidly and replacing CRT monitors and televisions in many homes and offices. These displays provide multiple benefits while comparing with CRT technology. Some advantages are discussed below:
Disadvantages of LCD
LCD has many advantages, but it also has some disadvantages, which are discussed below: