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1. OSCILLOSCOPE CATHODE RAY TUBE
PREPARED BY
Ketan nayak (140413117005)
Keyurmistry (140413117004)

2. INDEX
Sr No TOPIC NAME
1. INTRODUCTION
2. CIRCUIT DIAGRAM
3. WORKING OF a C.R.T
4. ADVANTAGES AND DISADVANTAGES

3. INTRODUCTION
• Kálmán Tihanyi, was a
Hungarian physicist,
Electrical Engineer and
Inventor of C.R.T.
• A Cathode Ray Tube (CRT) is a
specialized Vacuum tube in
which Images are produced
when an electron beam strikes a
Phosphorescent surface.

4. CIRCUIT DIAGRAM
• Parts of a CRT
 The features of a CRT can be split into 3 main sections:
1. The Electron Gun
2. Deflection System
3. Fluorescent Screen

5. ELECTRON GUN
• The role of this section is to produce electrons at a High, Fixed,
Velocity.
This is done through a process known as Thermionic Emission.
– A Filament in the Cathode is heated to the point where
its Electrons become loose.
– An Anode with a High Voltage applied to it Accelerates the
electrons towards the screen due to Electrostatic Attraction.
– On the way, the electrons pass through a series of Control
Grids which control the Brightness of the image produced.
– The more negative the grid, the darker the image and vice
versa.

6. DEFLECTION SYSTEM
• The role of the deflection system is to control the image
produced by controlling the position that the electrons hit
the screen.
• It consists of Two PERPENDICULAR sets of Electric/Magnetic
fields.
– This allows control over both horizontal and vertical axes.
– By controlling the Voltage applied to the fields, it is
possible to vary the deflection through Electrostatic
force/Motor effect.

7. FLUROSCENT SYSTEM
• The role of this part is to Display where the electrons are
hitting the CRT.
• It is a screen coated with a material that emits light when
struck by electrons.
– Zinc Sulfide or Phosphorus are two commonly used
materials.

8. C.R.T Advantages
• 1. Resolution and Aspect Ratio
They operate at any resolution, geometry and aspect ratio without the need for
rescaling the image.
• 2. Highest Resolutions
CRTs run at the highest pixel resolutions generally available.
• 3. Black-Level and Contrast
Produce a very dark black and the highest contrast levels normally available.
Suitable for use even in dimly lit or dark environments.
• 4. Color and Gray-Scale Accuracy
CRTs produce the very best color and gray-scale and are the reference standard for
all professional calibrations. They have a perfectly smooth gray-scale with an
infinite number of intensity levels. Other display technologies are expected to
reproduce the natural power-law Gamma curve of a CRT, but can only do so
approximately.
• 5. Motion Artifacts
CRTs have fast response times and no motion artifacts. Best for rapidly moving or
changing images.
• 6. Cost
CRTs are less expensive than comparable displays using other display technologies.

9. C.R.T DISADVANTAGES
• 1. Sharpness
The CRT's Gaussian beam profile produces images with softer edges that are not as
sharp as an LCD at its native resolution. Imperfect focus and color registration also
reduce sharpness. Generally sharper than LCDs at other than native resolutions.
• 2. Interference
All Color CRTs produce annoying Moiré patterns. Many monitors include Moiré
reduction, which normally doesn't eliminate the Moiré interference patterns entirely.
• 3. Brightness
Relatively bright but not as bright as LCDs. Not suitable for very brightly lit
environments.
• 4. Screen Shape
Some CRTs have a rounded spherical or cylindrical shape screen. Newer CRTs are flat.
• 5. Emissions
CRTs give off electric, magnetic and electromagnetic fields. There is considerable
controversy as to whether any of these pose a health hazard, particularly magnetic
fields. The most authoritative scientific studies conclude that they are not harmful but
some people remain unconvinced.
• 6. Physical
They are large, heavy, and bulky. They consume a lot of electricity and produce a lot of
heat.