About LCD – You all know about LCD already. All of you have heard about it already and many people have even used it. Yet many such people can be like this, which do not have any information about it. Its full form is “Liquid Crystal Display“. It is a flat panel display technology, which is commonly used in TVs and Computer monitors. It is also used on the mobile device’s screen, in laptops, tablets and smart phones.
LCD displays do not look different in comparison to CRT monitors, but also work very differently. These CRTs are not as large and bulky as those of monitors. Here the electrons are not fired on the glass screen, but the Liquid Crystal Display has a back light which provides light to all individuals’ pixels that are arranged like rectangular grid. All pixels remain red, green and blue sub-pixel which can be turned on and off. When the entire sub-pixel pixel is off, then it looks black. And when all sub-pixels is turned on, then it looks white. All of these individual levels can be adjusted to make red, green and blue light to match million color combinations. This was some information about LCD, let’s now know how it works and how many types it is and the other important Information. Then without delay, let’s start and know what the LCD is and how it works.
What is LCD?
As I have said before, what is the full form of LCD “Liquid Crystal Display” It was first discovered in 1888. Since then, it has been used to gradually increase its usage. This is a technology that is used according to the display. Where you can do many things like application status, display values, program debugging. Like LED and Plasma technology, the display also has very thin compared to CRT technology. LCD consumes very little power compared to LED and Gas-display because it works in the principle of blocking light and not emitting.
An LCD is usually made of either a passive matrix or an active matrix display grid. These active matrix LCD’s are also called thin film transistor (TFT) display. In the same passive matrix LCD, which is the grid of conductors, they are located on all the intersection of the grid with the pixels. Current is sent across two condensers on the grid for any pixel. In an active matrix, there is one transistor at all pixel intersection, so that they need less current to burn the pixel. Just because the current can be switched on and off easily in the active matrix display.
So that screen refresh time can also be improved. In some passive matrix Liquid Crystal Display dual scanning is kept indefinitely, which means that it can scan the grid twice. At the same time, with the help of the original technology, only one scan was done. But still active matrix is still a superior technology.
Working Principle of LCD
Back light of Working Principle of LCD also provides light source from behind the screen. This light is polarized, meaning only half light through the liquid crystal layer through shine. This liquid crystal is made from some solid part, made of some liquid substance, which can be easily twisted, by applying electric voltage. They block the polarized light when it remains off but reflects red, green and blue light when they are activated. All LCD screens have matrix of pixels which display the image on the screen. Earlier LCD’s used to have a passive matrix screen, which were used to control individual pixels by sending the charge in row and column.
Since very limited charges could be sent in every second, images in the passive-matrix screen appear blurry when the images were sent across the screen. Nowadays, modern LCD’s use active-matrix technology which includes thin film transistor, also called TFT. These transistors contain capacitors that enable individual pixels to retain the “actively” charge. Therefore, active-matrix LCD’s appear more efficient and more responsive than the passive-matrix display.
Types of LCD
LCD’s can generally be divided into two categories.
1. Field Effect Display (FED):
i) Field Effect Display of this type consists of “front” and “back” plagiarizer’s at right angle or 90 degree interchangeably.
ii) They are placed in 90 ° with each other
iii) Without electric excitation, which comes light here, “front” with polarize, it is usually revolve within 90 ° fluid.
2. Dynamic Scattering Display (DSD)
i) In this dynamic scattering display, mainly TWO pieces of glasses are sandwiched with a very thin layer of LC material.
ii) A transparent conductive coating is found in the dark faces of the glass.
3. Therefore, whenever the voltage is applied in it then the liquid crystal molecules themselves become realigned and begin to move randomly.
4. This creates a “Turbulence” from which it disperses the light and ultimately appears “White Appearance” in it.
Difference between LCD and LED
The full form of LCD is “liquid crystal display” and technically, both LED and LCD TVs are liquid crystal displays. Both of these two types of television technologies are similar to basic technology, and both of them have polarized glasses of two layers through which these liquid block and passes the crystals light. LED TVs subset is LCD TVs.
The full form of LED is “light emitting diodes” and differs significantly from the general LCD TVs, where LCD s use fluorescent lights, the use of light emitting diodes in the LED s. It happens. Along with this, the placement of those lights also differs. In LCD TV, the fluorescent light always stays behind the screen.
At the same time, light emitting diodes are placed behind the screen or around its edges in an LED TV. For these reasons, LED TVs are thinner than LCD s. With this, LED TVs run faster, better energy efficiency and this provides a much clearer and better picture compared to general LCD TVs.
How do colored pixels work?
In LCD TVs Here we will learn how to make these colors pixel works? How the pixels are switched off.
1. Light travels first to the back of the TV with light brightness.
2. A horizontal polarizing filter, which is placed in front of the light, blocks all the light waves, not only do they know which are horizontally vibrating.
3. Only those light waves can cross those which are vibrating horizontally.
4. A transistor lets switch off this pixel when it switches on the liquid crystal to make the power flow. With this the crystal gets straightens out and the light easily goes beyond it.
5. Light waves are emerging from liquid crystals and they are still vibrating horizontally.
6. By putting a vertical polarizing filter in front of these liquid crystals, it blocks blocking all the lights not only to light waves which are vertically vibrating. Therefore, this horizontally vibrating light which has come from traveling through this liquid crystal cannot move beyond this vertical filter.
7. No one can access the light screen at this point. In different words the pixel is dark now.
How Pixels are switched on?
1. The bright light behind the screen shines like before.
2. Horizontal polarizing filter that is placed in front of the light blocks all the light waves, do not just do them, which are horizontally vibrating.
3. Only those light waves can move forward, which are vibrating horizontally.
4. A transistor switches on does this when it turns off the pixel in the liquid crystal, then it turns off the power being turned into electricity. It has a crystal twist. This twisted crystal rotates light waves in 90 °, like they travel through it.
5. Light waves which enter this liquid crystal while vibrating horizontally, are exactly the same as these emerge vertically while vibrating.
6. The vertical polarizing filter stays in front of the liquid crystal, it blocks all the light waves, which are vibrating vertically. Later, these vertically vibrating lights which emerge from the liquid crystal can easily move from the vertical filter.
7. Here the pixel gets lit up. And red, blue, or green filter give this pixel its color.
What is the difference between LCD and Plasma?
A Plasma Screen is exactly the same as an LCD screen, but it works differently. Here all pixels are effectively a microscopic fluorescent lamp which glows with plasma. Plasma is a very hot form of gas where the atoms are blown away from one another, which can be negatively charged electrons and positively charged ions. They move very freely and produce fuzzy glow of light whenever they collide with each other. Plasma screens can be made very big compared to ordinary cathode-ray tube television but they are very costly.
CRT Vs LCD
CRT Here we will get some information about the advantages of these two, how they are different from each other. There is very little power consumption in the LCD compared to the CRT.
Advantages of LCD Monitors
- Required less power – CRT. This makes the LCD s produce very little heat.
- Smaller and weigh less – An LCD monitor is very thinner and lighter than a CRT monitor. You can also hang an LCD monitor on the wall of your house.
- More adjustable – LCD displays are highly adjustable compared to CRT displays. In LCD s, you can easily adjust the tilt, height, swivel, and orientation from horizontal to vertical mode.
- Low eye strain – Since every pixel in the LCD displays is turned on individually, it does not produce much flicker Such as in CRT displays. With this, LCD displays display text more effectively than the CRT displays.
Advantages of CRT Monitors
- Less expensive – These are much cheaper than LCD monitors Better color representation – Here we see a much better color representation in CRT displays.
- More responsive – In Historically, CRT monitors have seen very few problems such as ghosting and blurring, because the screen image is redraw here easily, compared to LCD monitors.
- Multiple resolutions- If you have different applications in your display. If you have to change then CRT Monitors will help you more in comparison to LCD.
- More rugged – we all know that CRT displays are very large, air is heavier but they are also very rugged. The more lightweight LCD display Delicate and easy to break if not caught correctly.
- Sharpness– LCD images are very sharp in their native resolution.
- Geometric Distortion in LCD Zero geometric distortion appears in the native resolution of your panel. Minor distortion is seen in other resolutions as images have to be descaled.
- Brightness -Because of the high peak intensity here, images are very bright.
- Screen Shape – Here the Screens is completely flat.
- Physical – These tend to be thinner than normal tones and have very small footprint. From which they consume very little electricity and produce less heat.
Disadvantages of LCD
- Resolution -Here all the fixed pixel resolution formats of all panels are already determined by the manufacture, which cannot be changed later.All other image resolutions require resealing, which later leads to significant image degradation, especially for fine text and graphics.
- Interference – Liquid Crystal Displays that use the analog input, they require careful adjustment of pixel tracking / phase so that they can reduce or eliminate digital noise, which is on any image.
- Viewing Angle – Here is the Limited viewing angle. Brightness, contrast, gamma and color mixtures also vary with viewing angle. And big angles may also have more contrast and color reversal.
- Black-level, Contrast and Color Saturation – LCD s have trouble producing black and very dark grays. Because of which it has lower contrast than CRT, and color saturation is also reduced for low-intensity colors. Therefore, it is not suitable for places with dim light.
- The bright end intensity scale of white saturation – It is easily overloaded, which leads to saturation and compression. Contrast Control requires careful adjustment to control it.
- Bad Pixels and Screen – Uniformity Liquid Crystal Displays can also have many weak and stuck pixels, which are permanently turned on or off. Some pixels are improperly connected with their adjoining pixels, rows, and columns. With this, panels are often uniformly illuminated by back light, which can cause uneven intensity and shading on screen.
- Motion artifacts – In this, the result of slow response times and scan rate can also result in degradation if the speed movement occurs and then the rapid changes of images .
- Aspect ratio – Always fixed resolution and aspect ratio is found in Aspect Ratio LCD s. So it is not possible to change .
- Cost – If you talk about its price then it is very expensive if we compare it to CRT. There are so many applications of Liquid Crystal Display application that I am going to tell you below.
Very common LCD applications
General Applications of LCD’s
i) Computer Monitor
(ii) Instrument Panels
iv) Aircraft cockpit displays
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