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LED TVs vs. Traditional LCD TVs:
LED TVs are more advanced versions of LCD TVs.
Both types use LCD technology and have flat-panel designs.
LED TVs are slimmer, brighter, and more detailed than traditional LCD TVs.
They function by illuminating LCD panels with LED backlighting.
LED TVs can utilize different types of LED backlighting1.
History of LEDs:
Scientists have been discovering ways to generate light from various materials since the early 1900s.
In the 1950s, studies around Gallium Arsenide (GaAs) led to the first official LED discoveries.
LEDs have evolved significantly over time, leading to the development of LED TVs1.
Working Principle of LEDs:
A semiconductor with extra holes is called P-type material.
Electrons can jump from hole to hole, creating movement.
A diode (N-type material bonded to P-type material) conducts electricity in only one direction.
When no voltage is applied, a depletion zone forms, preventing charge flow1.
Types of Backlighting:
LCD screens consist of two parts: the liquid crystal display and a backlight.
Two common backlight types:
Cold Cathode Fluorescent Backlights (CCFL): Used in older LCD TVs.
LED Backlights: Used in modern LED TVs for better power efficiency, contrast, and color accuracy.
LED TVs can be thinner due to smaller LEDs and may use edge lighting or full array backlighting1.
Remember, this is just a brief overview. If you need more detailed information or have specific questions, feel free to ask! 😊📺1.

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ChatsLED TVs vs. Traditional LCD TVs:
LED TVs are more advanced versions of LCD TVs.
Both types use LCD technology and have flat-panel designs.
LED TVs are slimmer, brighter, and more detailed than traditional LCD TVs.
They function by illuminating LCD panels with LED backlighting.
LED TVs can utilize different types of LED backlighting1.
History of LEDs:
Scientists have been discovering ways to generate light from various materials since the early 1900s.
In the 1950s, studies around Gallium Arsenide (GaAs) led to the first official LED discoveries.
LEDs have evolved significantly over time, leading to the development of LED TVs1.
Working Principle of LEDs:
A semiconductor with extra holes is called P-type material.
Electrons can jump from hole to hole, creating movement.
A diode (N-type material bonded to P-type material) conducts electricity in only one direction.
When no voltage is applied, a depletion zone forms, preventing charge flow1.
Types of Backlighting:
LCD screens consist of two parts: the liquid crystal display and a backlight.
Two common backlight types:
Cold Cathode Fluorescent Backlights (CCFL): Used in older LCD TVs.
LED Backlights: Used in modern LED TVs for better power efficiency, contrast, and color accuracy.
LED TVs can be kil

1. UNIT –II TELEVISION STSNDARDS AND SYSTEMS

2. Components of a TV system Interlacing Composite video signal Color TV Luminance and Chrominance Signal Monochrome and colour picture tubes Color picture tubes Color picture tv systems-NTSC ,PAL,SECAM Components of a TV Remote control and TV camera tubes,HDTV,LED,LCD TV,DTH TV

3. Television To see at a distance Visual information in the scene is converted to an electrical video signal for transmission to the receiver The image is reassembled on the fluorescent screen of the picture tube In monochrome television ,the picture is reproduced as shades of white , gray and black In color television the picture is reproduced in all their natural colors as the combination of red green and blue

4. Components of TV Picture Transmission Sound Transmission Picture reception

5. Components of TV

6. Monochrome TV ONE ELECTRON GUN CONTINUOUS PHOSPHOR COATING

7. Picture Transmission Monochrome TV Transmitter

8. Picture transmission tool

9. Sound transmission

10. Picture reception

11. Monochrome TV Receiver

12. Elements of a Picture Tube

13. Electron gun Control grid Accelerating grid Focusing grid

14. Cross sectional view about the neck of the picture tube

15. Picture tube circuit and associated controls

16. Production of video signal by Photoemission Production of video signal by Photoconduction

17. Cross sectional view of vidicon TV

18. Circuit for output signal

19. Leaky capacitor concept

20. Rear view of monochrome tv receiver

21. receiver

22. Function of a composite video signal

23. Sound signal Separation

24. Block diagram of AGC System

25. High voltage (EHT) Supply

26. Deflection circuit

27. Path of scanning beam in covering Picture Area

28. Waveform of current in the horizontal deflection coils Produces Linear scanning in the horizontal direction

29. INTERLACING

30. COMPOSITE VIDEO SIGNAL COLOUR TV PICTURE TUBE

31. Basics of composite video signal In TV Picture signal is a combinational of multiple signals. Camera Signal : Corresponding to the variation of light of given picture Synchronization Pulse : To Provide Synchronization Blanking Pulse : To make the retrace invisible

32. In TV ,There are 625lines in one frame One frame – Divided into two fields 1 to 312.5 lines and 312.5 to 625 lines. Again 1 st field from 1to 312.5 divided into trace 292.5 lines (1 to 292.5) and retrace 20 lines(292.5 to 312.5) 2 nd field from 312.5 to 625 lines again divided into trace(292.5 lines(312.5 to 605 lines)retrace 20 lines (605 to 325lines)

33. Composite video signal RANGE OF VIDEO SIGNAL V/V MAX = PERCENTAGE OF SIGNAL SYNCHRONIZATION

34. Camera Signal Lowest Amplitude at 12.5 % shows whitest part of the picture. Highest amplitude at 75% shows darkest part of the picture. Signal transmission : Negative Polarity transmission

35. Horizontal blanking Pulse Horizontal blanking pulse (12µs) has three portion Front Porch (1.5 µs) Fly black initiated with black level Horizontal synchronization pulse (4.7µs) Synchronization is done to Tx and Rx by Pulse Back Porch (5.8 µs) Fly back completed with black level.

36. HORIZONTAL BLANKING

37. HORIZONTAL BLANKING

38. BACK PORCH

39. TRACE and RETRACE

40. Vertical Synchronization Pulse It is of 2.5 line duration So it’s time period is 2.5 * 64 =160 µs At the end of first field vertical sync pulse is added at (312.5 to 315 lines)(2.5 lines) At the end of second field vertical sync pulse is added at (1 to 2.5 lines) One vertical sync pulse ends at half line period and one ends at full line period.

41. Vertical sync pulse 75% to 100 %

42. Vertical Blanking period It is the period during which picture information is completely suppressed and flyback retrace of field is initiated and completed. Its of 20 lines duration .so its time period is 20 * 64 µs = 1.28 ms

43. COLOUR TV PICTURE TUBE Basics Diagram of Picture tube Components Working Generation

44. Basics of colour TV Picture Tube The receiver of Colour TV receives Y, B-Y, R-Y video signals Y is Luminance signal Y= 0.3R+0.59G+0.11B B-Y,R-Y is having information regarding colours At the receiver of colour TV ,In delta gun ,Three guns are placed at 120 degree with each other

45. ANY COLOUR CAN BE MADE USING RED,GREEN & BLUE

46. The tube having a screen where three colour phosphor dots are arranged in groups known as triads.

47. Three colour beam passes through single hole of a shadow mask On dot triads screen, three dots at the same time Distance between shadow mask and dot triads is 1cm Triads are repeated and depending upon the size of the picture tube approx 1 million such dots forms 3.33 lac triads, triads are deposited on the glass tube. About 1 cm behind screen perforated metal sheet known as the shadow mask

48. The mask has one hole for every phosphor dot triad on the screen Ratio of electron passing through the shadow mask is 20 %. Other 80% electrons are dissipated as heat.

49. Three signals are forwarded to colour TV Y B-Y R-Y

50. Diagram of Colour TV Picture Tube

51. V’ K2 –V K = (V R –V Y )- (- V Y ) = V R V’ K2 –V K = (V G –V Y )- (- V Y ) = V G V’ K3 –V K = (V B –V Y )- (- V Y ) = V B

52. TV STANDARDS HDTV

53. NTSC COLOUR National Television Systems Committee Developed in US Compatible with Monochrome Receiver Consists of Luminance signal Y Chrominance Signal Field rate: 60 Hz Line rate:15750 Hz 526 Lines

54. NTSC Colour system

55. YIQ (NTSC) YIQ from RGB Y = .299R + .587G + .114B I = .74 (R - Y) - .27 (B - Y) Q = 0.48 (R - Y) + 0.41 (B - Y) YIQ with Y=0.5

56. PAL Phase Alternation by line Developed in Germany 625 lines

57. Generation of PAL system

58. Color Space: YUV PAL video standard Y is luminance UV are chrominance YUV from RGB Y = .299R + .587G + .114B U = 0.492 (B - Y) V = 0.877 (R - Y) U-V plane at Y=0.5 Y U V

59. Video Representation

60. HDTV To Overcome Limitations of Analog Television • Noise free pictures • Higher resolution images Widescreen / HDTV • No Ghosting • Enhanced Sound Services • Other Data services.

61. HDTV is generally recognized as a digital video broadcast with a minimum resolution of 1280 pixels wide and 720 pixels high, a rate of 30 or more frames/second and usually an aspect ratio of 16:9.

62. HDTV History Early 1980’s: – Japan created analog HDTV Mid-1980s: US, trying to stay competitive, decided to go digital Congress gave stations a separate channel for transition to digital broadcast with the goal of all stations using digital broadcasts by 2006.

63. Less than 15% of US homes have HDTV capabilities Approximately 21% of stations have digital broadcasts

64. A standard definition analog television uses a cathode ray tube with an electron gun to guide the path of an electron beam to “paint” 480 vertical lines across the face of the screen. Each time the beam strikes a dot of phosphor, light is produced. For a color television set, each spot consists of a group of three phosphor elements; one for each primary color.

65. How HD Works

66. Implementation in technologies Plasma – Like LCD monitors, plasma HDTV sets are thin and are made up of cells that correspond to pixels sandwiched between glass plates. Plasma cells contain three separate gas-fill sub-cells, one for each color. When a current is applied to a sub-cell, it ionizes the gas emitting ultraviolet light. The ultraviolet light in turn excites fluorescent substances in the sub-cells that emit red, blue or green light. DLP – Digital light processing is a technology used in projection displays. In DLP monitors, light is reflected off an array of microscopic hinged mirrors. Each tiny mirror corresponds to a visible pixel. The light is channeled through a lens onto the surface of the screen. Single chip DLP projectors can display 16.7 million colors. 3- chip projectors can display 35 trillion colors. LCoS – Similar to DLP, LCoS projection systems use liquid crystals instead of mirrors to block light. The liquid crystals are arranged in a grid in front of a highly reflective surface.

67. HD TV Screen Refresh Rates A rate of 24 frames/second (progressive) has been the movie film standard since the mid-20’s The television industry has used a rate of 60 frames/second (interlaced) since the 40’s Newer HDTV’s are being marketed as 120 Hz and 240 Hz using circuitry to help reduce motion blur

68. Technical Aspects

69. Frame rate conversion - 3-2 pulldown

70. What is a format Number of active pixels per line Number of active lines per frame Scanning mode Picture aspect ratio Frame rate Two main Standards are SMPTE 274 M SMPTE 296 M

71. Archiving High Definition Standard definition video 720 pixels 576 lines 1- hour programme file size : 72 GB High definition video 1980 pixels 1080 lines 1- hour programme file size : from374 GB to 673 GB*

72. Judging simply on pixel count, a 1080i HDTV image is 6 - 9 times better than a standard, NTSC image Audio is also improved

73. HDTV & SDTV Comparison

74. Advantages By using lower-definition signals, one channel can be split into several channels Extra channels used for: information services (data casting) – music – Internet services

75. HDTV Features Provides up to 60 frames/sec screen writing Uses MPEG-2 data compression – source info data rate is 1.2Gbps – broadcast data rate is 20Mbps • Square pixels 1/4 the size of analog TV’s pixels

76. Types of HDTV

77. Connecting To Analog TV

78. Connecting To Digital TV

79. Impact of HDTV Broadcasters & consumers spend more $ Increased visual clarity has forced designers to spend considerably more money on sets, set dressings Blu -Ray vs HD-DVD

80. Camera Tubes types Image Orthicon, Vidicon , Plumbicon .

81. Camera Tubes A TV camera tube may be called the eye of a TV system. Some of the more important functions must be, ( i ) Sensitivity to visible light, (ii) Wide dynamic range with respect to light intensity, and (iii)ability to resolve details while viewing a multi-element scene.

82. THANK YOU