• Heart of a TV camera is a camera tube.
• Camera tube –converts optical information into electrical signal.
• Amplitude proportional to brightness.
• Optical image is focused by a lens assembly to a rectangular glass face –plate.
• Transparent conductive coating at the inner side of the glass faces plate.
• On which is laid a thin layer of photo conductive material having a very high resistance when no light falls on it.
• Resistance DECREASES when the intensity increases.
• Electron beam –used to pick up the picture information AVAILABLE on the target plate in terms of varying resistance.

Beam is formed by an electron gun:

• Deflection coils are fed separately from two oscillators-continuously generates saw tooth wave forms having DIFFERENT desired frequency uses magnetic deflection.
• Deflection by first coil-horizontal motion of BEAMS and then brings quickly to left side to commence the trace of next line.
• Deflection by second coil-Vertical motion and its quick retrace back to the top to start the process allover again.
• Encounters different resistance across the target plate.
• Result in a flow of current which varies in magnitude during scanning.

We get the true information of the scene:

• Scanning converts the in antenna formation existing in space and time coordinates into time variation only –called a video signal.
• Video signal is amplified-amplitude modulated with channel picture carrier frequency.

The major problems during this conversion are:

• Poor sensitivity.
• Poor resolution.
• Higher noise level.
• Improper spectral response.
• Instability.
• Poor CONTRAST range.
• Difficulties in processing the output signal.

Beam is formed by an electron gun:

We get the true information of the scene:

The major problems during this conversion are: