this ppt will gives u the information about graphic terminal that is crt monitor

1. CAD/CAM
TOPIC: GRAPHIC TERMINAL (CRT MONITOR)
By
J KUMAR CHANDRA,
ASST. PROF.,
DEPARTMENT OF ME,
NNRG-HYDERABAD

2. • Emissive display  convert electrical energy into light
- Cathode ray tube (CRT)
- Plasma panels (gas-discharge display)
• Non-Emissive display  optical effect: convert sunlight or light fromother
source into graphic patterns.
- Liquid-crystal device (LCD) – flat panel
Displays

3. It Consists of..
CRT
Anode
Cathode
Shadow mask
Focusing coil
Deflecting coil
Fluorescent screen

4. How It Works?

5. How It Works?
Cathode rays are emitted by an electron gun.
accelerated by a high positive voltage near the face of the tube
forced into a narrow stream by a focusing system
directed toward a point on the screen by the magnetic field generated bythe
deflection coils
hit onto the phosphor-coated screen
phosphor emits visible light, whose intensity depends on the numberof
electrons striking on the screen

6. How It Works?
Electrons travel through a vacuum sealed container from thecathode
(negative) to the anode (positive).
Because the electrons are negatively charged, they are repelled away from the
cathode, and move across the tube to the anode.
The ray can be affected by a magnet because of its relation to positiveand
negative charges.
A CRT monitor contains millions of tiny red, green, and blue phosphor dots that
glow when struck by an electron beam. Electron beam travels across the screen to
create a visible image.
Dot mask ensures proper pixel is lit.

7. Phosphore
It is a semi-conducteur material which emits visible radiation in response
to the impact of electrons.
when it absorbs energy from some source such as an electron beam, it
releases a portion of this energy in the form oflight.
.

8. Color Monitors
A display monitor capable of displaying manycolors.
Color Monitors works like a monochrome one, except that there are three
electron beams instead of one.
The three guns represent additive colors (red, green and blue) althoughthe
beam they emit are colorless.
Each pixel includes three phosphors, red, green and blue, arranged ina
triangle.
When the beam of each of these guns are combined and focused on apixel,
the phosphors light up.

9. Mixing of Colors

10. https://www.youtube.com/watch
?v=6BgcrRjqnKE
Working animation of CRT Monitor

11. Types of CRT display principles
1. RASTAR SCAN DISPLAY
2. RANDOM SCAN DISPLAY

12. CRT Display Principles
Electron beam swept across screen one row at a time from top to bottomin
raster-scan.

13. CRT Display Principles
Sample of Random-Scan displays principles.
Beam-penetration is used.

14. • Phosphor Persistence (PP)
- the light output decays exponentially with time.
- a phosphor’s persistence is defined as the time from the removal of
excitation to the moment of decaying the light to one-tenth of its
original intensity
• Refresh rate (RR)
- number of times per second the image is redrawn.
• Resolution
- the maximum number of points that can be displayed without overlapon
a CRT
- high-definition system, e.g. 1280 * 1024 pixels
- resolution depends on the type of phosphor, the intensity to be
displayed, focusing and deflection systems, size of videomemory
Properties of the CRT

15. Pros of CRT
The cathode rayed tube can easily increase the monitor’s brightnessby
reflecting the light.
They produce more colours
The Cathode Ray Tube monitors have lower price rate than theLCD
display or Plasma display.
The quality of the image displayed on a Cathode Ray Tube is superiorto
the LCD and Plasma monitors.
The contrast features of the cathode ray tube monitor areconsidered
highly excellent.

16. Cons of CRT
They have a big back and take up space on desk.
The electromagnetic fields emitted by CRT monitors constitute a health
hazard to the functioning of living cells.
CRTs emit a small amount of X-ray band radiation which can result in a
health hazard.
Constant refreshing of CRT monitors can result in headache.
CRTs operate at very high voltage which can overheat system or result in an
implosion.
Within a CRT a strong vacuum exists in it and can also result in a implosion
They are heavy to pick up and carry around