20-08-2012, 05:07 PM
Future Trends of Televisions
[attachment=32225]
CRT (cathode ray tube)
Invented in 1897 by Karl Ferdinand Braun
Standard for televisions until recent years
How CRT works
A=cathode
B=conductive coating
C=anode
D=phosphor-coated screen
E=electron beams
F=shadow mask
Uses R,G,and B phosphors
The three beams are accelerated and focused by the anode
Plasma Displays
invented at the University of Illinois at Urbana-Champaign in 1964 for the PLATO Computer System
1983 IBM introduced 19” orange on black monochrome
Gas made up of free flowing ions and electrons
How Plasmas work
Made up of tiny fluorescent lights
Each pixel contains a red, green, and blue light
xenon and neon gas is contained in hundreds of thousands of cells positioned between two plates of glass along with electrodes
When charged, it releases ultraviolet photons which act with the phosphors
This brings their energy level up, when it goes back down it is released as visible light photons
LCD (liquid crystal display)
Liquid crystals were first discovered in 1888, by Austrian botanist Friedrich Reinitzer
First experimental LCD by RCA in 1968
Based on properties of polarized light
How LCD works
Formed by two glass layers called substrates
One is in charge of columns, and the other is in charge of rows
Liquid crystals are sandwiched in between these two layers
Uses a grid to charge specific pixels
When this happens the crystals untwist and allow light to pass through
OLED (organic light emitting diode)
Developed by Eastman-Kodak
Competing against LCD and plasma television displays
How OLED works
Has two to three layers of organic material the emissive and conductive layer
These are sandwiched in between the cathode and anode
When an electrical current is sent through the LED, it moves from the cathode to anode (negative to positive)
The cathode gives electrons to the emissive layer, and the anode takes away electrons from the conductive layer
When they recombine, the extra energy is given off as light which corresponds to the type of organic molecule
The voltage also depends on how much light is given off
[attachment=32225]
CRT (cathode ray tube)
Invented in 1897 by Karl Ferdinand Braun
Standard for televisions until recent years
How CRT works
A=cathode
B=conductive coating
C=anode
D=phosphor-coated screen
E=electron beams
F=shadow mask
Uses R,G,and B phosphors
The three beams are accelerated and focused by the anode
Plasma Displays
invented at the University of Illinois at Urbana-Champaign in 1964 for the PLATO Computer System
1983 IBM introduced 19” orange on black monochrome
Gas made up of free flowing ions and electrons
How Plasmas work
Made up of tiny fluorescent lights
Each pixel contains a red, green, and blue light
xenon and neon gas is contained in hundreds of thousands of cells positioned between two plates of glass along with electrodes
When charged, it releases ultraviolet photons which act with the phosphors
This brings their energy level up, when it goes back down it is released as visible light photons
LCD (liquid crystal display)
Liquid crystals were first discovered in 1888, by Austrian botanist Friedrich Reinitzer
First experimental LCD by RCA in 1968
Based on properties of polarized light
How LCD works
Formed by two glass layers called substrates
One is in charge of columns, and the other is in charge of rows
Liquid crystals are sandwiched in between these two layers
Uses a grid to charge specific pixels
When this happens the crystals untwist and allow light to pass through
OLED (organic light emitting diode)
Developed by Eastman-Kodak
Competing against LCD and plasma television displays
How OLED works
Has two to three layers of organic material the emissive and conductive layer
These are sandwiched in between the cathode and anode
When an electrical current is sent through the LED, it moves from the cathode to anode (negative to positive)
The cathode gives electrons to the emissive layer, and the anode takes away electrons from the conductive layer
When they recombine, the extra energy is given off as light which corresponds to the type of organic molecule
The voltage also depends on how much light is given off