Future Trends of Televisions
By: Rion Núñez
Team 11
Types of Televisions
CRT (cathode ray tube) Plasma LCD (liquid crystal display) DLP (digital light processing) OLED (organic light emitting diode) SED (surface-conduction electron-emitter
display)
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
CRT Advantages
High color fidelity and contrast
Better resolution with moving images
CRT Disadvantages
susceptible to phosphor burn-in
Bulky and heavy sets
Consume a lot of energy
Old technology
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
Plasma Advantages
Brighter than CRTs
Flat panel
Lowering in cost
Plasma Disadvantages
Susceptible to phosphor burn-in
Not well used in bright rooms
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
LCD Advantages
More efficient use of electricity than CRT
Produce little glare compared to plasmas
Largest screen sizes than other flat panels
LCD Disadvantages
Manufacturers often reject about 40 % of the panels that come off the assembly line
Color contrast is not the best
DLP (digital light processing)
Developed by Texas instruments
Created by Dr. Larry Hornbeck in 1987
How DLP works One DLP chip contains more than 2 million
mirrors Each mirror made of aluminum represents
one pixel on the screen The chip will rapidly decode a bit-streamed
image code that enters through the semiconductor
It changes the data from interlaced to progressive scanning and adjusts the picture
The mirrors then tilt off and on to allow light to pass and can do it up to 5,000 times per second
The is then sent through a transparent, spinning color wheel that is synchronized with the chip into red, green, and blue, light, and can produce 16.7 million colors
DLP Advantages
Insusceptible to phosphor burn-in
More affordable than plasmas and LCDs
DLP Disadvantages
Not as thin as other high definition displays
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 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
OLED Advantages
Thinner, lighter, more flexible Can be plastic instead of glass Does not require backlighting Brighter than traditional LED’s Consume less power than LED’s Large field of view around 170 degrees
OLED Disadvantages
Easily damaged by water
High manufacturing costs
Blue OLED films have shorter lifespan than Red and Green
SED (surface-conduction electron-emitter display)
Formed in 2004 between Toshiba and Canon
Created SED Co. LTD for developing and producing SED technology
Canon for electron source technology
Toshiba for the display
How SED works Uses millions of cathode ray tubes
called SCEs (surface-conduction electron emitters)
They have a layer of carbon with a gap down the center
Half of the carbon layer is connected to a negative electrode, the other to a positive
Activates SCEs all at once instead of CRT going one row at a time
Does not use interlacing
SED Advantages
Lower power consumption Fast video response High contrast of color 3cm thick Better picture than LCD and Plasma
SED Disadvantages
Cost
Availability
Extra
http://www.youtube.com/watch?v=hxv7mmKHRhs
Sources http://electronics.howstuffworks.com/lcd.htm http://electronics.howstuffworks.com/oled1.htm http://electronics.howstuffworks.com/plasma-display.htm http://entertainment.howstuffworks.com/sed-tv.htm http://www.howstuffworks.com/tv.htm http://www.howstuffworks.com/tv3.htm http://electronics.howstuffworks.com/dlp.htm http://reviews.cnet.com/8301-12760_7-9673322-5.html?tag=txt http://reviews.cnet.com/8301-12760_7-9674057-5.html?tag=txt
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