Display Panels: LCD, LED, OLED, AMOLED, and S-AMOLED
Table of Contents
display panels- There are majorly five panel types of display or display panel other are also there but mainly these five are used:
- LCD: liquid crystal display
- LED: Light emitting diode
- OLED: Organic light emitting diode
- AMOLED: Active matrix organic light display
- S-AMOLED: super active matrix organic light
Now before we talk about these panels in detail we will discuss about two terms which is related to this topic which are polarizer and polarization.
Firstly polarization, in this we will get to another terms which are polarized light and unpolarized light. So a polarized light wave is that light wave in which vibration occur in a single plane and an unpolarized light wave is that light wave in which vibration occur in more than one plane. Now let’s finally understand polarization. Polarization is a process of transforming unpolarized light wave into polarized light wave.
Polarizer is type of optical filter which lets light wave of specific polarization passing through it while blocking light waves of other polarization. In simple words it allows light wave to move in particular direction while cancelling other light waves which are in different direction.
Cathode Ray tube:
This is older technology which is not used today. In CRT monitors there was a cathode ray tube due to which it is called CRT monitors. It consists of the electron gun which emits electron on the phosphorous screen and with the help of it image is formed on the screen. The signals that is send from the video adapter reaches to the electronic gun through cables. There are three electronic guns for each RGB color Red, Green, and Blue. These three color mixes with each other and form other colors. The electrons beams emitted from the electronic gun can be focussed in different direction using magnetic force. So that it can reach on the whole screen and produce display. The electron beams when hit the phosphorus screen it produces Red, Green, and Blue colours. The CRT monitor was heavy, large and bulky in size. It consumes more energy. The disadvantage of this technology is that it emits radiations which are harmful for human eyes and health. Due to this reason the CRT monitor is now replaced with the LCD monitor.
Flat Panel Display:
The flat panel display replaced the CRT. The flat panel display takes small space as compare to the CRT. It is small in size and consumes less power. Now days mostly computer and laptops uses flat panel display. Flat panel display does not emit any harmful radiation. Flat panel display uses three types of technology:
- Gas plasma
LCD (Liquid Crystal Display):
Now the first display panel type we have got is liquid crystal display or LCD it is a type of display panel that uses liquid crystals technology along with polarizers and a cold cathode fluorescent lamp as backlight to provide lightning. These liquid crystals do not emit light directly instead of it. They use a backlight or reflector to illuminate screen and produce image in colour or monochrome. The LCD works better in sunlight. The electricity passes through the liquid crystal and produce image.The color accuracy of the LCD is not very good. The LCD works on three things:
- Polarization filters
- Liquid crystals
When light emits from source then the light wave vibrates in different direction in horizontal, vertical and diagonal. Then the polarization filters which are sheet of plastic which consists of vertical lines which are very near to each other. The important thing about filter is that when it is place in front of light then only vertical waves can pass through this filter. The horizontal waves are blocked by the filter. If we rotate this filter by 90 degree then this filter will block the vertical waves and pass the horizontal waves. Then we have liquid crystals which was discovered by an Australian scientist in 1888 which is state between the solid and liquid. The interesting thing about liquid crystal is that when the current is passes through it. The molecules changes its direction.
Now on basis of technology used LCD panel can also be primarily of two types:
- TFT: thin film transistor LCD
This type of LCD used active matrix technology which means that at every pixel transistor and capacitor is separately attached. The TFT contrast is better than LCD. But the disadvantage is that it consume more power due to which the battery timing of the mobile or laptop is minimum and also from the side the display view is not good. TFT technology is not available in the latest mobiles.
- IPS LCD: in plane switching LCD
IPS LCD is the advanced form of the TFT technology the viewing angle and colour contrast is better than TFT. In IPS technology there are two transistors for each pixel and also the back light is maximum. It consumes less power as compare to TFT due to which it’s battery life is better than TFT.
Other types are also there like twisted pneumatic and vertical alignment and advanced fringe field switching.
LED (Light Emitting display):
The next display panel is light emitting diode or simply led. A led display panel also uses liquid crystal technology but instead of cold cathode fluorescent lamps as back lightning led display panel use an area of small light emitting diodes or LEDs as backlighting to illuminate the screen.
LED might seem like a new type of screen but in fact the LED is just an LCD screen but instead of using fluorescent light as the backlight it uses LEDs this gives the LED screen some new advantages for example it’s more energy efficient since LEDs consume less power also LED screens can be made very thinner than LCDs because they don’t have that bulky backlight. LEDs also have slightly more accurate colors than LCDs what’s also nice about LEDs is that black is slightly more black than on an LCD screen.
OLED (Organic light emitting diode):
So the next display panel is organic light emitting diode or simply OLED. OLED display panel is made by putting a series of organic thin films between two conductors and when electric current is applied to this type of structure it emits a bright light unlike LCDS and LEDS.They don’t require backlight so they can be thinner and way lesser.So finally OLED uses an organic substance that glows when electric current is introduced and these displays can be thin and flexible too. Now to show something in OLED display it do not require all the display to turn on and only those pixel work which want to display something and other pixels will remain off. Due to which the black portion of the OLED display looks very good compare to LCD. It also consumes less power due to which the battery life will be good. The contrast ratio of OLED technology is better than LCD because the black pixels remain off. The disadvantage is that in sunlight its light is compromised and we may face problem in watching compare to an LCD display. LCD based phone is relatively cheaper than OLED display phone. The screen of the OLED display is very thinner because it does not need back light. Due to which OLED display phone is very thinner and more flexible than LCD phones. The very important benefit of it is that it is folded display. So we can decrease the phone size by folding the screen.
AMOLED (Active matrix organic light emitting diode):
Now the next display panel is active matrix organic light emitting diode or simply AMOLED in AMOLED display panel. The first two words a and m refers to active and matrix respectively. The active matrix refers to the technology which is used for addressing pixels. AMOLED display panel uses a thin film transistor or TFT which contains a storage capacitor which maintains the line pixel states. So AMOLED display panel is a type of OLED which uses active matrix technology.The AMOLED is called active matrix because it consists of different layers for display formation. The anode layer is integrated with thin film transistor TFT which means it does not depend upon on the external circuit to glow the pixel.
As it does not require external circuit due to which it consume less power.
S-AMOLED (Super active matrix organic light emitting diode):
Now the last display type we have got is super active matrix organic light emitting diode or simply assemble it as S-AMOLED is an AMOLED display which has an integrated touch function. So instead of having a layer which recognizes touches on top of screen that layer is embedded directly into screen assembly is a marketing term that is used by Samsung which refers to a display technology. Now you may be thinking what is the difference between S-AMOLED and AMOLED. So the term super make it distinguishable from its older version AMOLED and S-AMOLED are not only similar by name but also similar in function. The difference between them is the integrated touch function technology which S-AMOLED have and AMOLED have not. The super AMOLED is integrated with the touch sensor. As in the AMOLED we were used touch sensor digitizer which was integrated in the S-AMOLED due to which the thickness was decreased and due to removal of the touch sensor digitizer battery consumption is also decreased. In S-AMOLED light reflection is less as compare to the AMOLED. Both shares the same pixel arrangement