COLOR CRT MONITORS IN COMPUTER GRAPHICS

FOR COMPUTER SCIENCE STUDENTS

1. COLOR CRT DISPLAY
NEHRUREVATHY
DEPARTMENT OF BCA

2. COLOR CRT MONITORS
•It is used by the combination of phosphors.
•The phosphorsare different colors.
•Two popular approaches are:
1.Beam Penetration Method
2.Shadow-Mask Method

3. 1. Beam Penetration Method:
•Random scan monitors
•CRT screen is coated with two phosphor colors: redand green.
•Displayed color depends on the speed of the electron beam.
•produces four colors only:
i.e.,red, green, orangeand yellow.
•speed of electron:
❖ slow---red color(hit the red layer)
❖ high speed---green color(hit the green color)
❖ Medium speed---orange or yellow color(hit the intermediate screen)

4. BEAM PENETRATION METHOD

5. Beam Penetration Method:
•Advantage:
1. Inexpensive
•Disadvantages:
1.Only four colors are possible
2.Quality of pictures are not good.

6. SHADOW MASK METHOD
•Raster san system
•Three phosphor colordots:
1.Red phosphor
2.Green phosphor
3.Blue phosphor
•Three electron guns are used.

7. SHADOW MASK METHOD
•Uses shadow mask grid behind the phosphor screen.
•Three electron beams are deflected and focussed as a group onto a
shadow mask –form a dot triangle
•Another configuration of the electron gun –inline arrangement
Dot triangle

8. SHADOW MASK METHOD
Inline arrangement
Three electron guns are placed in a linear format.

9. SHADOW MASK GRID

10. SHADOW MASK METHOD
•Advantages:
1.Realisitic image
2.Million different colorsto be generated.
3.shadow scenes are possible
•Disadvantages:
1.Expensive
2.poor resolution

11. DIRECT VIEW STORAGE TUBES(DVST)

12. DIRECT VIEW STORAGE TUBES
•Use the random scan approach
generate the image on the CRT screen
•Storage Tubes:
It refers to the ability of the screen to retain the image which has
been projected against it.

13. DIRECT VIEW STORAGE TUBES

14. FUNCTION OF GUNS:
FUNCTIONS OF GUNS
PRIMARY GUNS
FLOOD GUNS/SECONDARY
GUNS
STORE THE PICTURE PATTERN
MAINTAIN THE PICTURE
DISPLAY

15. DIRECT VIEW STORAGE TUBES
•ADVANTAGES:
1.No refreshing is needed
2.High resolution
3.Less expensive
DISADVANTAGES:
1. Not possible to erase the part of a picture.
2.do not display colors

16. FLAT PANEL DISPLAY

17. FLAT PANEL DISPLAY
•It refers to a class of video devices that have reduced volume,weight
and power requirement compare to CRT.
EX:
CALCULATOR,POCKET VIDEO GAMES

18. FLAT PANEL DISPLAY
EXAMPLES EXAMPLES
FLAT PANEL DISPLAY
EMISSIVE DISPLAY NONEMISSIVE DISPLAY
PLASMA PANELS AND LED LCD

19. EMISSIVE DISPLAY
•Converts electrical energy into light.
•Examples are:
1.Plasma Panels
2.Thin film electroluminescent display
3.LED(Light Emitting Diodes)

20. PLASMA PANEL DISPLAY
•Also called asgas-discharge displays
•Construtedby filling the region between two glass plates with a
mixture of gases(neon)
•Two conductors:
1.vertical conductors break down into a glowing
plasma of electrons and ions.
2.horizontal conductors

21. PLASMA PANEL DISPLAY

22. PLASMA PANEL DISPLAY
•Firing voltages are applied
To refresh the pixel position 60 times per sec.
Advantage:
Display brighter
Disadvantage:
Display color and grayscales

23. THIN FILM ELECTROLUMINESCENT DISPLAYS
•Similar to plasma panel
•Region between the glass plates is filled with a phosphor

24. THIN FILM ELECTROLUMINESCENT DISPLAYS
•Disadvantages:
1.requires more power than plasma panel
2. good color and gray scale are difficult to achieve.

25. LIGHT EMITTING DIODE(LED)
•Matrix of diodes is arranged to form the pixel positions in the display.
•Picture definition is stored in a refresh buffer.
Scan-line refreshing of a CRT
Information is read from the refresh buffer
Converted to the voltage levels
Applied to the diodes
To produce the light patterns in the display.

26. LIQUID CRYSTAL DISPLAY(LCD)
•Non-Emissive device
•It produce picture by passing polarized light from the surrounding or
from an internal light source through a liquid-crystal material that
transmits the light.
•LCD uses the liquid-crystal material between two glass plates;
•Each plate is the right angle to each other between plates liquid is
filled.
•One glass plate consists of rows of conductors arranged in vertical
direction.
•Another glass plate is consisting of a row of conductors arranged in
horizontal direction.

27. LIQUID CRYSTAL DISPLAY(LCD)
•The pixel position is determined by the intersection of the vertical &
horizontal conductor.
•This position is an active part of the screen.
•Liquid crystal display is temperature dependent. It is between zero to
seventy degree Celsius.
•It is flat and requires very little power to operate.

29. LIQUID CRYSTAL DISPLAY(LCD)
•Advantage:
❖Low power consumption.
❖Small Size
❖Low Cost
•Disadvantage:
❖LCDs are temperature-dependent (0-70°C)
❖LCDs do not emit light; as a result, the image has very little contrast.
❖LCDs have no color capability.
❖The resolution is not as good as that of a CRT.

30. THANK YOU