Tv transmitters & receiver
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Wokring of Plumbicon,Vidicon,CCD,B/W Rx & TX
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Tv transmitters & receiver
- 3. Basic Monochrome Television Receiver 3 Prof.Shirke P.Y.
- 4. TV Camera Heart of a TV camera is a Camera tube Camera tube – converts optical information into corresponding electrical signal Amplitude proportional to brightness Optical image is focused by a lens assembly to a rectangular glass faceplate Transparent conductive coating at the inner side of the glass face-plate On which is laid a thin layer of photoconductive 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 – deflected by a pair of deflection coils kept mutually perpendicular on the glass plate - to achieve scanning of the entire target area 4 10/23/2013 sk-mes-vkm
- 5. Types of Camera Pick Up Tube Vidicon: Improvement of signal to noise ratio Improvement of contrast High image lag Plumbicon Lower image lag (follow up of organ motions) Higher quantum noise level Solid state camera based on CCD Digital fluoroscopy spot films are limited in resolution, since they depend on the TV camera . 5 Prof.Shirke P.Y.
- 6. Camera tube have a diameter of approximately 1 inch and a length of 6 inches. 6
- 7. Simplified cross-sectional view of a Vidicon TV camera tube 7 Prof.Shirke P.Y.
- 9. Working of Vidicon 9 Prof.Shirke P.Y.
- 10. Vidicon Target & Equivalent ckt of Pixel 10 Prof.Shirke P.Y.
- 11. Application of vidicon Close circuit TV system Earlier type of vidicon were used only where there was no fast movement , because of inherent lag 11 Prof.Shirke P.Y.
- 12. Characteristic of Vidicon Dark Current Vidicon Lag Beam Lag Photoconductive 12 Lag Persistence Lag Prof.Shirke P.Y.
- 13. Plumbicon Lower image lag. It has fast response and produce high quality pictures at low light level. It has small size and light weight and has low power operating characteristics . It 13 is similar to vidicon tube except small change in target plate Prof.Shirke P.Y.
- 15. Plumbicon Target & Equivalent ckt of Pixel 15 Prof.Shirke P.Y.
- 16. Solid state camera based on CCD 16 Prof.Shirke P.Y.
- 17. Solid state camera based on CCD Equivalent ckt 17 Prof.Shirke P.Y.
- 18. •Charge-Coupled Devices (CCDs) Each electrode is connected to a storage capacitor (TFT) 1980s CCD were developed and replaced TV tubes and miniaturized imaging devices. • Light photons enter the silicon layer, ionization of the light separates the e-. A layer of microscopic electrodes beneath the silicon acts as a ground for the freed electrons. Movement of charges can be measured by a circuit. • 18
- 20. Colour Camera tube 20 Prof.Shirke P.Y.
- 21. Colour Camera tube 21 Prof.Shirke P.Y.
- 23. Construction of picture tube 23 Prof.Shirke P.Y.
- 24. What is inside picture tube ? 24 Prof.Shirke P.Y.
- 26. •DEFLECTION YOKE It may be noted that a perpendicular displacement results because the magnetic field due to each coil reacts with the magnetic field of the electron beam to produce a force that deflects the electrons at right angles to both the beam axis and the deflection field. 26 Prof.Shirke P.Y.
- 28. PARTS AND WORK PRINCIPLE CRT COLOURED Electron guns 2. Electron beams 3. Focusing coils 4. Deflection coils 5. Anode 6. Mask 7. Phosphor layers 8. Close-up of the phosphor 1. Parts CRT colour 28 Prof.Shirke P.Y.
- 29. •Delta-gun colour picture tube 29 (a) guns viewed from the base (b) electron beams, shadow mask and dot-triad phosphor screen (c) showing application of ‘Y’ and colour difference signals between the cathodes and control grids Prof.Shirke P.Y.
- 30. The screen has a number of phosphorus that will be fluorescent when exposed to fire electrons produced by electron gun. This electron beam be turned by magnetic field that controlled by vertical spool and horizontal (spool yoke). Magnified view of a shadow mask color CRT 30 Prof.Shirke P.Y.
- 31. PRECISION-IN-LINE (P.I.L.) COLOUR PICTURE TUBE (a) in-line guns (b) electron beams, aperture grille and striped three colour phosphor screen(c) mountings on neck and bowl of the tube. 31 Prof.Shirke P.Y.
- 32. Electron at shoot off and will hit dots phosphor will produce bright light and can be seen in the screen. Tube also have mask color, to place phosphor's dots so correct electron beams. There 3 circles phosphor that is red, blue and green. when described based on sequence the colour, so seen to like picture. Magnified view of an aperture grille color CRT 32 Prof.Shirke P.Y.
- 35. Basic Monochrome Television Receiver 35 Prof.Shirke P.Y.