16-11-2012, 06:27 PM
Principle of LCD Display
[attachment=39900]
Introduction to Liquid Crystal Displays
Consists of an array of tiny segments (called pixels) that can be manipulated to present information.
Using polarization of lights to display objects.
Use only ambient light to illuminate the display.
Common wrist watch and pocket calculator to an advanced VGA computer screen
Different types of LCDs
Passive Matrix LCDs (AMLCD) and Active Matrix LCDs (AMLCD)
Passive Twisted Nematic Displays (TNLCD)
Super Twisted nematic LCD (STNLCD)
Thin Film Transistor LCD (TFT LCD)
Reflective LCD
Rear Projection LCD
Operating Principle
Molecules movement
Offline (no voltage is applied)
Along the upper plate : Point in direction 'a'
Along the lower plate : Point in direction 'b‘
Forcing the liquid crystals into a twisted structural arrangement. (Resultant force)
Advantage of LCD over CRT
Smaller size—AMLCDs occupy approximately 60 percent less space than CRT displays—an important feature when office space is limited.
Lower power consumption—AMLCDs typically consume about half the power and emit much less heat than CRT displays.
Lighter weight—AMLCDs weigh approximately 70 percent less than CRT displays of comparable size.
No electromagnetic fields—AMLCDs do not emit electromagnetic fields and are not susceptible to them. Thus, they are suitable for use in areas where CRTs cannot be used.
Longer life—AMLCDs have a longer useful life than CRTs; however, they may require replacement of the backlight.
Display Addressing
In multiplex addressing, a larger number of pixels are involved. When the elements are in a regular order, they can be addressed by their row and column instead of each element being driven separately. This reduces the complexity of the circuitry because each pixel no longer needs its own driver circuit.
If you have a 10x10 matrix of pixels, with direct addressing, you need 100 individual drivers. However, if you use multiplex addressing, you only need 20 drivers, one for each row and one for each column.
This is a tremendous advantage, especially as displays become larger and larger.
[attachment=39900]
Introduction to Liquid Crystal Displays
Consists of an array of tiny segments (called pixels) that can be manipulated to present information.
Using polarization of lights to display objects.
Use only ambient light to illuminate the display.
Common wrist watch and pocket calculator to an advanced VGA computer screen
Different types of LCDs
Passive Matrix LCDs (AMLCD) and Active Matrix LCDs (AMLCD)
Passive Twisted Nematic Displays (TNLCD)
Super Twisted nematic LCD (STNLCD)
Thin Film Transistor LCD (TFT LCD)
Reflective LCD
Rear Projection LCD
Operating Principle
Molecules movement
Offline (no voltage is applied)
Along the upper plate : Point in direction 'a'
Along the lower plate : Point in direction 'b‘
Forcing the liquid crystals into a twisted structural arrangement. (Resultant force)
Advantage of LCD over CRT
Smaller size—AMLCDs occupy approximately 60 percent less space than CRT displays—an important feature when office space is limited.
Lower power consumption—AMLCDs typically consume about half the power and emit much less heat than CRT displays.
Lighter weight—AMLCDs weigh approximately 70 percent less than CRT displays of comparable size.
No electromagnetic fields—AMLCDs do not emit electromagnetic fields and are not susceptible to them. Thus, they are suitable for use in areas where CRTs cannot be used.
Longer life—AMLCDs have a longer useful life than CRTs; however, they may require replacement of the backlight.
Display Addressing
In multiplex addressing, a larger number of pixels are involved. When the elements are in a regular order, they can be addressed by their row and column instead of each element being driven separately. This reduces the complexity of the circuitry because each pixel no longer needs its own driver circuit.
If you have a 10x10 matrix of pixels, with direct addressing, you need 100 individual drivers. However, if you use multiplex addressing, you only need 20 drivers, one for each row and one for each column.
This is a tremendous advantage, especially as displays become larger and larger.