Liquid Crystal Display is the full form of LCD. LCD is a flat panel display system primarily seen on television and computer screens, now also used by mobile phones. Such LCDs are quite different from previous CRT displays and use liquid crystals rather than cathode rays as their primary mode of operation.
An LCD consists of millions of pixels made of crystal and arranged in a rectangular pattern on the LCD panel. The LCD has a backlight that brings light to each pixel. Each pixel has a subpixel (RGB), red, green and blue, which can be turned off or on. When all subpixels are off, it's black, while all subpixels are 100 percent on, then it's white.
LCD Construction
- LCD is a combination of two phases of liquid and solid matter
- The solid element is the crystal, and the combination of liquid and crystal makes the image clear
- The LCD has two layers consisting of two polarized filters and electrodes
- The LCD screen works by blocking the light beam rather than releasing the light
- Active Matrix Grid and Passive Matrix Grid are two kinds of pixel grids in LCD
- Active Matrix Grid is a new technology used in smartphones with LCD screens
- Passive Matrix Grid is a legacy technology used in some legacy applications
Principles of LCD
LCD works on the principle of emitting colors from liquid crystals. The LCD was identified in 1888. An LCD is an electronically modulated optical device that contains segments filled with liquid crystals. They used LCD liquid crystals and polarized lighting to display images. When current is applied to LCD TVs, there is a wide bright light that is reflected towards the audience.
Advantages of LCD
- The most significant advantage of LCD is low price, energy efficiency and lower power consumption
- The LCD is smaller and thinner and is very flexible
- The LCD offers excellent contrast, brightness and resolution, so image accuracy is crystal clear
- The emissivity of an LCD screen is slightly less than that of a CRT monitor
- Using CMOS circuit boards, LCDs can be customized so that making an LCD is quite easy
Disadvantages
- LCDs require external light sources to illuminate the pixels, because if the light source is lost, the LCD will not display any image.
- An LCD monitor is less accurate.
- The visibility of the image depends on the brightness.
- For LCDs, the aspect ratio and resolution are specified.
- The LCD has an irregular intensity scale and generates frequencies below 256 different intensities.
- For LCDs, the color intensity associated with the reduced black level decreases at a lower intensity level.
- LCD has a small viewing range and the brightness is affected when we look at the screen from an angle, then the color of the image changes in our eyes.