1

Graphic adapters and monitors – the summary

2

Outline

• The summary of principles of displaying the information – adapters and monitors.

• Black and white monitors. • Digital monitors.• Analog monitors.• LCD monitors and analog interface.• LCD monitors and DVI interface.

3

How CRT monitor is constructed?

CRT – Cathode Ray Tube Controller

This is the situation in black and white monitor – one electron beam.

Color monitor – three electron beams.

4

The image on screen – how it works?

• Black and white monitor (mono monitor) – just two colors are displayed.

• Information about color is stored in video memory as „0“ and „1“.

• This information is transported to monitor as analog signal.

• The voltage is brought to anode, the beam of electrons is either accelerated (the fluorescent layer at this dot is illuminated) or not (the fluorescent layer at this dot is not illuminated)

• The levels of grey color – not only two values of voltage are available, but more values. The number of analog values depends on the number of bits used to represent the information about the dot color. The digital value is converted into analog voltage which is transported to monitor and its anode.

5

The image on screen – mono monitor

Grapfic adapter

cable mon

itor

System bus

Video memory: 0/1

(dot is illuminated/is not illuminated

Cable: 0/1 voltage

The consequence: the dots on monitor are illuminated/are illuminated according to the information brought from video memory

Typical for text mode.

6

The image on screen – mono monitor (graphics)

Grapfics adapter

cable

mon

itor

System bus

Video memory: several bits 0/1 for each pixel

analog voltage

Analog voltage – it is generated in graphics adapter by converting binary representation of the pixel color (in fact level of grey color) to the analog voltage transported through the cable to monitor.

With this voltage applied to anode, the beam of electrons is accelerated – different voltage – different energy with which the beam of electrons hits the fluorescent layer (pixel)on the screen – different intensity of pixel.

7

The image on screen – color monitor (digital control)

Graphics adapter

cable mon

itor

Video memory: 0/1

(the pixel lights/does not light), this information is available for each color R,G, B

Cable: 0/1 for each color R,G,B

System bus

8

The image on screen – color monitor (analog control)

Graphics adapter

cable mon

itor

Video memory: certain number of bits 6/8/ …. for each color R,G,B

The conversion to analog voltage – for each color R, G, B one DAC is needed

Cable: analog voltage for each color R,G,B

System bus

9

LCD monitor, DVI interface

Graphics adapter

cable mon

itor

cable: 3 color components, the information is transported serially in digital form

The reasons for serial interface: faster communication, wider bandwidth, higher resolution.