What is LCD and how does it work?

I know what is LCD ( you know about it in advance ) . You all heard about it somewhere before and many of you may have used it as well. Yet there may be many such people who do not have any information about it. Its full form is ” Liquid Crystal Display “. This is a flat panel display technology that is commonly used in TVs and computer monitors. It is also used with it on the screen of the mobile device, in laptops, tablets and smartphones.

What is LCD
What is LCD

LCD displays not only look different than CRT monitors but they also do these tasks very differently. They are not so big and bulky like CRT monitors. Here the electrons are not fired on the glass screen but the LCD has a backlight that provides light to all the individual pixels which are arranged like rectangular grids. All the pixels have red, green and blue sub-pixel mehzud which can be turned on and off. It looks black when all the sub-pixels of the pixel are turned off. And when all the sub-pixels are turned on, then it appears white. Million color combinations can be found by adjusting the red, green and blue light of all these individual levels.

This was some information about the LCD, let’s now know how it works and how it is and other important information. Then without delay, let’s start and know what is LCD and how it works.

What is LCD?

Like I said earlier, what is the full form of LCD ” Liquid Crystal Display “. It was first discovered in 1888 . Since then, it is used to grow slowly. This is a technology that is used according to the display. Where you can do many tasks like application status, display values, program debugging. Like LED and Plasma technology, the display in it is very thin compared to CRT technology. LCD consumes very less power compared to LED and gas-display because they work under the principle of blocking light and not emitting.

An LCD is usually composed of either a passive matrix or an active matrix display grid. This active matrix LCD is also called thin film transistor (TFT) display. The grid of conductors in passive matrix LCD with pixels are located at all intersection of grid. Current is sent across the grid to two conductors for any pixel. All active pixels in an active matrix have a transistor position at intersection so that they require less current to burn the pixel.

For this reason, the current in active matrix display can be switched on and off very easily, so that the screen refresh time can also be improved. Some passive matrix LCDs have dual scanning mehsud which means that they can scan the grid twice, in the same current as with the help of original technology, it was scanned only once. But even then active matrix is ​​still a superior technology.

Working Principle of LCD

The backlight of the LCD provides even light source from behind the screen. This light is polarized, meaning only half the light shines through the liquid crystal layer. This liquid crystal is made up of some solid part, some liquid substance which can be easily twisted by applying electric voltage to it. They block polarized light when it is off, but reflect red, green and blue light when they remain active.

All LCD screens have matrix of pixels that display the image on the screen. Earlier LCDs used to have passive matrix screens, which used to control individual pixels by sending the charge to the 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 LCDs use active-matrix technology which contains thin film transistor which is also known as TFT. These transistors have capacitors that enable individual pixels to “actively” charge. Therefore active-matrix LCDs appear more efficient and more responsive than passive-matrix display.

Types of LCD:

LCD’s can be divided into two categories by common means.
I.   Field Effect Display (FED):
i) This type of Field Effect Display consists of “Front” and “Back” polarizer’s at right angles or 90 degrees with each other.
ii) They are placed in 90 ° with each other
iii) Without electrical excitation, the light that comes here is normally revolved by the “Front” polarizer in 90 ° within the fluid.

II.  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 glass.
iii) Therefore, as soon as the voltage is applied in it, the liquid crystal molecules are automatically realigned and start to move randomly.
iv) This creates a “turbulence” and through which it disperses the light and ultimately a ” White Appearance ” appears in it.

Difference Between LCD and LED

LCD has full form “liquid crystal display” and technically, both LED and LCD TVs are liquid crystal displays. Both these television types have the same basic technology and both of them have two layers of polarized glass through which it blocks and passes the liquid crystals light. If viewed, LED TVs are subset of LCD TVs.

LEDs have a full form of ” light emitting diodes ” and differ greatly from general LCD TVs, where fluorescent lights are used in LCDs, whereas LEDs use light emitting diodes. With this the placement of those lights also differ. In LCD TVs, fluorescent light is always behind the screen. At the same time, light emitting diodes are placed behind or around its edges in an LED TV. For these reasons, LED TVs look thinner than LCDs. With it, LED TVs run faster, have better energy efficiency and provide clearer, better picture as compared to normal LCD TVs.

How colored pixels work in LCD TVs

Here we will know how these colored pixels work.

How pixels are switched off

1. Light travels first to the front of the bright light in the back of the TV.

2. A horizontal polarizing filter that is placed in front of the light blocks all the light waves, while not knowing only those which are vibrating horizontally.

3. Only those light waves can cross them that are vibrating horizontally.

4. A transistor switches off this pixel when it switches it on for electricity to flow from the liquid crystal. This makes the crystal straightens out and the light easily goes beyond it without any change.

5. Light waves emerge from the liquid crystal and they are still vibrating horizontally.

6. By placing a vertical polarizing filter in front of these liquid crystals, it blocks all the lights, not only those light waves which are vibrating vertically. Therefore, these horizontally vibrating lights that travel through this liquid crystal are not able to move beyond this vertical filter.

7. No light can reach the screen in this point. In different words, the pixel is still dark.

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, while not knowing only those which are vibrating horizontally.

3. Only those light waves can move forward which are vibrating horizontally.

4. A transistor switches on when it switches off the pixel when it switches off the electricity flowing in the liquid crystal. This causes a crystal twist. This twisted crystal rotates the light waves in 90 ° as they travel through it.

5. Light waves that enter into this liquid crystal vibrate horizontally in exactly the same way it emerges vibrating vertically.

6. The vertical polarizing filter which is located in front of the liquid crystal blocks all the light waves leaving only those which are vibrating vertically. Later these vertically vibrating light that emerges from the liquid crystal can easily move beyond the vertical filter.

7. Pixel lit up here. And red, blue, or green filter assign their colors to this pixel.

What is the difference between LCD and Plasma?

A plasma screen looks exactly like an LCD screen, but it works in a completely different way. Here all the pixels are effectively a microscopic fluorescent lamp that glows with plasma. Plasma is a very hot form of gas where the atoms are blown apart from each other so that negatively charged electrons and positively charged ions can be separated. They move very freely and produce a fuzzy glow of light whenever they collide with each other. Plasma Screen can be made very large compared to ordinary cathode-ray tube television but they are very expensive.

LCD vs. CRT

Here we will get some information about the advantages of these two, how they are different from each other.

Advantages of LCD Monitors

  • Require less power – LCD has very less power consumption as compared to CRT. This causes LCDs to produce very little heat.
  • Smaller and weigh less – An LCD monitor is much thinner and lighter than a CRT monitor. You can also hang an LCD monitor on the wall of your home.
  • More adjustable – LCD displays are much more adjustable than CRT displays. In LCDs, you can easily adjust tilt, height, swivel, and orientation from horizontal to vertical mode.
  • Less eye strain – Since each pixel is individually turned on in LCD displays, they do not produce much flicker as in CRT displays. With this, LCD displays display text much better than CRT displays.

Advantages of CRT Monitors

  • Less expensive – It is much cheaper than LCD monitor.
  • Better color representation – Here we can see much better color representation in CRT displays compared to LCD.
  • More responsive – Historically, CRT monitors have very few problems such as ghosting and blurring as the screen image is redrawed more easily compared to LCD monitors.
  • Multiple resolutions – If you have to change your display for different application, then CRT Monitors will help you more than it, LCD.
  • More rugged – We all know that CRT displays are much bigger, air heavier but they are also very rugged, whereas LCD displays are much lighter and more delicate and break easily if correct. Not caught in the way then.

LCD Advantages

1. Sharpness
LCD images are very sharp in their native resolution.

2. Zero geometric distortion is visible in Geometric Distortion
LCD in the native resolution of your panel. Minor distortion is visible in other resolutions because images have to be rescaled.

3. Brightness
Here, due to the high peak intensity, the images look very bright.

4. Screen Shape
Here Screens are completely perfectly flat.

5. Physical
They look thinner than normal and have very small footprint. Due to which they consume very less electricity and produce less heat.

Disadvantages of LCD

1. Resolution
Here the fixed pixel resolution format of all the panels are already determined by manufacture which cannot be changed later. All other image resolutions require rescaling, which subsequently leads to significant image degradation, particularly for fine text and graphics.

2. Interference
LCDs that use analog input require careful adjustment of pixel tracking / phase so that it can reduce or eliminate digital noise that occurs on an image.

3. Viewing Angle
Limited viewing angle is here. Brightness, contrast, gamma and color mixtures also vary with the viewing angle. And large angles can also have more contrast and color reversal.

4. Black-Level, Contrast and Color Saturation
LCDs have trouble producing black and very dark grays. Due to this, it has lower contrast than CRT and color saturation is also reduced for low-intensity colors. Therefore it is not suitable for dim light spaces.

5. The bright end intensity scale of White Saturation
LCD gets easily overloaded, leading to saturation and compression. Contrast control requires careful adjustment to control it.

6. Bad Pixels and Screen Uniformity
LCDs can also have many weak and stuck pixels, which are permanently on or off. Some pixels are improperly associated with their adjoining pixels, rows and columns. Along with this, the panels are also often illuminated uniformly through the backlight, due to which uneven intensity and shading can be seen above the screen.

7. Motion artifacts
Due to slow response times and scan rate, conversion result can also be greatly degrade if speed movement occurred and rapid change of images occurs.

8. Fixed
resolution and aspect ratio are always found in Aspect Ratio LCDs. So it is not possible to change it.

9. Cost
If we talk about its price then it is very expensive if we compare it with CRT.

Application of LCD

There are many applications of LCD, which I am going to tell you below.

Common LCD applications:
I. Calculators
II.Watches
III.Clocks
IV.Telephones

General Applications of LCD’s:
i) Computer Monitors (Computer Screens)
ii) Instrument Panels
iii) Televisions
iv) Aircraft cockpit displays
v) Signage

I sincerely hope that I have given you complete information about what is LCD and I hope you all have understood about LCD. I request all of you readers that you too should share this information in your neighborhood, relatives and friends, so that there will be awareness among us and it will benefit everyone. I need your support so that I can convey more new information to you.

It has always been my endeavor that I always help my readers or readers from all sides, if you people have any doubt of any kind, then you can ask me irresponsibly. I will definitely try to solve those Doubts. How did you like this article LCD, tell us by writing a comment so that we too have a chance to learn something from your ideas and improve something. Facebook

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