19-06-2012, 04:09 PM
CRT PRESENTATION
[attachment=24830]
INTRODUCTION
Early computers communicated with the user with either indicator lamps or hard copy printers, but today, the primary output device is the electronic display.
This is usually the CRT display, although other technologies are available. The enabling display technology for portable computers and the latest personal digital assistants(PDA) is the liquid crystal display.
CRT ADVANTAGE
Low cost because of volume of production.
Speed of updating and the retention of image is good.
Colour display is available.
Text and graphics display modes.
CRT DISADVANTAGE
Large size and weight: Typical CRT displays are at least as deep as they are wide
High voltage and power consumption. Also generate a lot of heat.
CRT displays are glass vacuum tubes, and are therefore relatively fragile.
The microprocessor interface is relatively complex.
CRT INTERFACE SIGNAL
Horizontal sync: Retraces beam to the left edge of the screen.
Horizontal oscillator: Saw-tooth signal that sweeps the beam horizontally across the screen.
Vertical sync: Causes beam to retrace to the top of the screen.
Vertical oscillator: Saw-tooth signal applied to the vertical deflection amplifier to move the beam down the screen.
Video signal: Determines the intensity of the beam that will strike the screen. The signal is amplified and applied as the accelerating voltage in the CRT.
[attachment=24830]
INTRODUCTION
Early computers communicated with the user with either indicator lamps or hard copy printers, but today, the primary output device is the electronic display.
This is usually the CRT display, although other technologies are available. The enabling display technology for portable computers and the latest personal digital assistants(PDA) is the liquid crystal display.
CRT ADVANTAGE
Low cost because of volume of production.
Speed of updating and the retention of image is good.
Colour display is available.
Text and graphics display modes.
CRT DISADVANTAGE
Large size and weight: Typical CRT displays are at least as deep as they are wide
High voltage and power consumption. Also generate a lot of heat.
CRT displays are glass vacuum tubes, and are therefore relatively fragile.
The microprocessor interface is relatively complex.
CRT INTERFACE SIGNAL
Horizontal sync: Retraces beam to the left edge of the screen.
Horizontal oscillator: Saw-tooth signal that sweeps the beam horizontally across the screen.
Vertical sync: Causes beam to retrace to the top of the screen.
Vertical oscillator: Saw-tooth signal applied to the vertical deflection amplifier to move the beam down the screen.
Video signal: Determines the intensity of the beam that will strike the screen. The signal is amplified and applied as the accelerating voltage in the CRT.