Page 33 - DCAP504_Computer Graphics

Computer Graphics

Figure 3.3 illustrates how a Cathode Ray Tube works.

Figure 3.3: Cathode Ray Tube

In figure 3.3, the conical glass tube is used for CRT tube. An electronic gun is placed at the narrow end.
The electrons emitted from the gun are passed through the magnetic system called yoke. The electronic
beam falls on the broader surface of the CRT tube. The broader surface of CRT tube is single coated
with phosphorus which reflects the beam to make it fall on computer screen.
Figure 3.4: Focusing Grids

In figure 3.4, we see that the focusing grids such as one horizontal and another vertical help in focusing
the beam on to the screen. The deflection of the beam depends on the direction (positive or negative)
and the intensity of the fields. The suitable combinations of grids are used to focus the beam on to the
screen. This helps to illuminate any point on the screen which in turn helps to illuminate any graphic
picture, thereby making it easy to trace the graphic picture.

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