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Chapter 23 Television and Video Display Units © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Objectives Explain.

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Presentation on theme: "Chapter 23 Television and Video Display Units © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Objectives Explain."— Presentation transcript:

1

2 Chapter 23 Television and Video Display Units

3 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Objectives Explain the steps in the transmission of a television signal. Discuss the scanning process. Identify circuits in both black-and-white and color television receivers and explain their functions.

4 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Objectives Identify the size and makeup of a television channel. Discuss a variety of television innovations, including video cassette recorders, remote control, and satellite television. List the benefits of HDTV, as compared to analog television.

5 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Objectives Explain the difference between multicasting and datacasting. Discuss the compression technique of MPEG2. Discuss the various flat-panel technologies.

6 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Television Signals Television cameras Scanning Composite video signals Basic CRT controls

7 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Television Cameras Picture elements Camera sees a scene as a combination of picture elements Photoelectric cells in the camera respond to scene by producing a voltage Voltages are amplified for AM carrier wave

8 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Image Orthicons Varying degrees of light cause electrons to be emitted on the target side of the cathode and form an electronic image

9 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Scanning Electron beam responds to point-to-point brilliance of a picture Interlace system used in United States has 525 scanning lines –Scans odd numbered lines of pattern first, and then scans even numbered lines Fields Frames

10 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Scanning (Cont.) FCC sets frame frequency 30 frames per second Horizontal deflection oscillator Vertical deflection oscillator The beam scans as it moves left to right Beam must return to top to scan again after reaching the bottom

11 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Scanning (Cont.) Deflection yoke Synchronization (sync) pulseSynchronization (sync) pulse Horizontal hold Vertical hold

12 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Composite Video Signals All video signals are formed the same way FCC sets standards Contain picture and sound information –Video is AM signal –Audio is FM signal

13 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Composite Video Signals (Cont.) First 75% of amplitude transmits video information Remaining 25% is for sync pulses Higher amplitudes of video information produce darker areas in the picture

14 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Composite Video Signals (Cont.) Screen is driven back to the pedestal, or blanking level Sync pulse is sent in infrablack region for oscillator synchronization

15 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Basic CRT Controls CRT is used to produce images in television sets Bias controlling current is brightness controlbrightness control Raster can be seen when TV is on a vacant channelRaster (RCA)

16 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Review How does a television camera transmit video to television? The photoelectric cells in a camera produce voltages. The voltages are amplified and used for modulation of the AM carrier wave, which is then transmitted to the home receiver

17 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Review What is scanning? The point-to-point examination of a picture

18 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Review How many scanning lines are used in the scanning system of the United States? 525

19 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Review What is a raster? The lines on a TV screen when a vacant channel is showing

20 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Television Receivers Black-and-white television receivers Color television receivers Television channels

21 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Black-and-White Television Receivers RF amplifier stageRF amplifier –Similar to function in superheterodyne radio –Provides constant gain and selectivity –Video signal amplified and fed to mixer Mixer stageMixer –Intermediate frequency is produced –Fine-tuningFine-tuning

22 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Black-and-White Television Receivers (Cont.) Tuner, or front endTunerfront end –Put together in the factory –No adjustments should be made on these without thorough understanding PIX-IF amplifiers –Amplify broad band of frequencies –Voltage gain is reduced –Intercarrier system

23 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Black-and-White Television Receivers (Cont.) Video detector, or demodulator, stageVideo detectordemodulator –Same detection process as radio –Video signal is separated and fed to next stage

24 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Black-and-White Television Receivers (Cont.) Video amplifiers Sound IF amplifiers FM audio detectors AF amplifiers Sync separators Sync amplifiers Horizontal AFCs Horizontal oscillators Horizontal outputs Horizontal output transformers (HOTs)Horizontal output transformers (HOTs) High voltage rectifiers Dampers Vertical oscillators Vertical outputs

25 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Special-Purpose Circuits DC restoration –Average value of video signal taken from detector –Used to set bias on the CRT AGC –Provides fairly constant output from detector –Varies gain of amplifiers –Rectifies video signal to produce negative voltage

26 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Color Television Receivers Developed in late 1940s by RCA Laboratories Shadow mask picture tubes (Sylvania-GTE)

27 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Color Television Receivers (Cont.) Three colors used in color television Any color can be produced on the screen by combining red, blue, and green

28 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Color Television Receivers (Cont.) Delta-type tubesDelta-type –Three electron guns in neck assembly of picture tube –Shadow mask or aperture ensures the electron beams strike the dots correctly (Sylvania-GTE)

29 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Color Television Receivers (Cont.) Color line is made by mixing the electron beams In-line gun assembliesIn-line Color television can produce both color and black-and-white pictures

30 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Television Channels FCC assigns portions of radio frequency spectrum for television channels –Very high frequency (VHF)Very high frequency (VHF) –Ultra high frequency (UHF)Ultra high frequency (UHF)

31 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Television Channels (Cont.) Frequencies of at least 4 MHz are needed to send a clear, sharp picture Upper sideband in commercial TV is transmitted without attenuation Vestigial-sideband filter partly removes lower sideband at transmitter Sound is transmitted as frequency- modulated signal at center frequency

32 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Review What changes the frequency of the oscillator slightly to provide the best response? Fine-tuning

33 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Review What is the voltage amplifier stage that increases sync pulses? Sync amplifier

34 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Review What are two special purpose circuits that have been used to improve the basic television circuit? DC restoration and automatic gain control (AGC)

35 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Review What invention made color television possible? Shadow mask picture tube

36 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Television Innovations Video cassette recorders (VCRs) Digital video recorder (DVRs) Remote controls Large-screen projection TVs Satellite TVs

37 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. VCRs Can record and play back videotapes Most have four video headsvideo heads Magnetic tape with iron oxide

38 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. VCRs (Cont.) Can record –Voice –Video –Speed information –End of tape location –Copyright –Anticopy coding

39 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. DVRs Combine computer and television components Form a television receiver Receive television signal and can record the program Hard disk drive used for recording medium Capable of recording and storage

40 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Remote Controls Application of infrared light and digital techniques Digital code sent out of remote control Infrared sensor on TV amplifies and decodes signal

41 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Large-Screen Projection TVs Use special electron gun assemblies to project three separate images onto a screen Loss of clarity of video image 525 lines per frame become distracting No real magnification

42 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Satellite TVs Geostationary orbit First communications satellite was launched in 1962 Amplifier increases strength of communication signal for its broadcast back to earth Carries both standard traveling wave tubes and solid-state power amplifiers

43 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Communication Satellites

44 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Satellite Signals Signals made by communication stations on earth are beamed up to satellites Amplified by satellite and then sent back to earth

45 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Satellite Transmission Focal point Feedhorn

46 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Coaxial Cable Designed to carry high frequency signals Limits radio waves generated from center core conductor to the area between the core conductor and the shield The shield absorbs radio signal emanating from core conductor as high frequency passes through

47 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. FAKRA SMB Connectors Very small connectors Designed for small diameter coaxial cable or micro-coaxial cable Used for automotive satellite radio and antenna connections Smallest connector used at this time

48 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Review What part of a VCR reads information from the recorded tape during playback? Video head

49 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Review What is combined to form a DVR? A television signal and hard disk drive

50 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Review Describe the signals sent to and from a satellite. The signal sent up from a studio is a narrow signal targeting the satellite, while the signal sent down from the satellite is a wide signal designed to cover a large area of the earth

51 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Review What part of a satellite dish acts as a receiver? A feedhorn

52 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Improvements to Analog Television Analog television merged with digital systems used by computer monitors Many features were added Greater color-depth control

53 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. High Definition Television (HDTV) FCC approved of digital television standard in 1996 Allows for higher resolutions and wider display screen than analog systems Uses digital broadcasting techniques More information-rich data to be transmitted

54 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Broadcasting Multiple Channels Digital broadcasting can broadcast multiple channels in same bandwidth Multicasting Datacasting

55 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. HDTV Systems Digital camera to record images at high resolution Digital receiver to convert received broadcasts into image and sound Display unit capable of producing images at HDTV resolution

56 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Charged Coupled Devices (CCDs)

57 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Digital Camera Technology CCD converts individual packets of electrical charge into series of analog signals representing level of light amplitude at each photo sensor location Analog-to-digital converter (ADC) Once converted, digital pattern can be stored or transmitted

58 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Three-CCD Systems Three sets of CCD sensors used for full-color images and higher resolutions

59 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. HDTV Picture Quality National Television Standards Committee (NTSC) formed analog standardsNational Television Standards Committee (NTSC) Advanced Television Systems Committee (ATSC) developed digital standardsAdvanced Television Systems Committee (ATSC)

60 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. ATSC Standards 18 scanning formats Progressive scanning Frame rate Aspect ratio –16:9 –4:3 HDTV capable of 720p and 1080i vertical lines

61 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Analog Quality vs. Digital Quality Convert scan lines to maximum number of pixels pixels –480 × 440 pixels for analog –1920 × 1080 pixels for HDTV Moving Picture Experts Group developed MPEG2 standard MPEG2 Sound quality improvements Enhanced definition television (EDTV)

62 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Digital Light Projection (DLP) Television Developed based on digital mirror device (DMD) DMD can contain over 1.3 million mirrors DMD combined with light source and lens to create DLP system (Courtesy of Texas Instruments)

63 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Flat-Panel Displays Many televisions now use flat-panel technology instead of picture tubes Control individual pixels electrically Vertical and horizontal conductors

64 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Gas-Plasma Displays Electro-luminescence Consist of millions of cells between two glass plates Controlled by varying pulses of current

65 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Liquid Crystal Display (LCD)Liquid Crystal Display (LCD) Panels Most common flat-panel displays Two categories –Active –Passive

66 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. How Color LCDs Work Backlight generates light Polarized light Liquid crystal between two filters Light passing through filters depends on amount of voltage applied

67 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Passive-MatrixPassive-Matrix Display Grid of semitransparent conductors run to each crystal Two major circuits –Columns –Rows Response time is slow because current must travel along row and column until it arrives at designated pixels

68 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Active-MatrixActive-Matrix Display Provides better image than passive-matrix Constant supply of voltage to each cell Results in brighter picture Thin film transistor liquid crystal displays (TFT-LCDs)Thin film transistor liquid crystal displays (TFT-LCDs)

69 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. LCD vs. CRT Displays LCDs are smaller and lighter than CRTs LCDs require less power to run LCDs generate less heat LCDs create more detailed images LCDs produce less electromagnetic interference LCDs do not have industry-wide standard LCDs cost more for the same size of CRT LCDs have difficulty scaling images properly without distortion

70 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Display ResolutionResolution Higher resolution results in more detailed images Images displayed at lower resolutions lose their sharpness

71 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Philips SXGA Triple-Input Display Controllers Accept input from analog, digital, and parallel sources –Analog input accepts UHF and VHF frequencies –Digital input accepts HDTV broadcasts from cable and computer systems –Parallel interface accepts input from USB connections

72 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Standards Organizations Video Electronics Standards Organization (VESA) Digital Flat Panel (DFP) –Led by Compaq Digital Visual Interface (DVI) –Led by Intel

73 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Home Theater Connector Types RF and F-type Composite video S-video Component video High Definition Multimedia Interface ToskLink

74 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. RF and F-Type Connections Support poorest quality of video images Found on older technologies Use standard coaxial cable

75 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Composite Video Cables Use only one cable for video, two for stereo sound Provide better signal than RF or F-type connections Provide worse signal than S-video

76 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. S-Video Connectors Four-pin or nine-pin connectors Separate signals for video signal chrominance and luminance No way to misconnect audio and video cables Video-in and video-out (VIVO) configurations

77 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Component Video Connectors Better quality than S-video Found on high- performance devices Do not carry audio signal

78 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. High Definition Multimedia Interface Connectors Supply video and audio in uncompressed all- digital signal format Exceed HDTV standard Colorimetry

79 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. ToskLink Connectors Limited to audio Support signals between home theater equipment Provide connections for fiber optic cable

80 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Review What is multicasting? Broadcasting multiple channels within the same bandwidth

81 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Review What is datacasting? Transmitting additional information along with a video image

82 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Review Which component does HDTV use in place of the analog televisions vacuum tube imaging? Charged coupled device (CCD)

83 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Review What committees standards have been designed to replace the original television and video standards in the United States? Advanced Television Systems Committee (ATSC)

84 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Review What is the purpose of the MPEG2 standard? To increase the amount of video data transmitted in an HDTV system

85 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Review Which flat-panel display system operates on the principle of electro-luminescence? Gas-plasma displays

86 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. For Discussion Discuss the controls found in a television receiver. Discuss various types of video display. Discuss the transition from analog to digital television.

87 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Active-matrix –A display in which each individual cell in the grid has its own individual transistor.

88 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Advanced Television Systems Committee (ATSC) –A committee, established in 1983, that developed standards for digital television broadcasting and receivers. These standards, adopted by the FCC, have been designed to eventually replace the NTSC standards. AF amplifier –Used to amplify audio frequencies.

89 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Aspect ratio –The ratio of width to height of a television picture. Aspect ratio standards can be either 4:3 or 16:9. Brightness control –Control from a TV remote that changes the bias on the control grid.

90 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Charged coupled device (CCD) –An integrated circuit consisting of an array of photo sensors that convert light from an image into electrical energy. CCDs are commonly found in scanners and digital cameras.

91 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Damper –Stage that dampens out oscillations in the deflection yoke after retrace in a television set. Used to prevent oscillations in the horizontal output transformer.

92 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Datacasting –A digital broadcasting technique that allows for the transmittal of additional information along with the video image. Stock prices, weather reports, sports scores, background or human interest stories about the actors in the movie being viewed, or any information found on the Internet can be incorporated into the display screen.

93 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Deflection yoke –Coils that surround a picture tube. Delta-type –The first color picture tube, using three electron guns, a screen, and a shadow mask. Demodulator –Device used to remove the video portion of a signal from a carrier wave.

94 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Electro-luminescence –The display of light created when a high frequency signal passes through a solid or liquid, resulting in the release of photons.

95 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Enhanced definition television (EDTV) –A system that receives digital transmissions, but displays images at 480p or higher. The fact that it can receive high definition television transmissions and decode them makes it an enhanced system. Feedhorn –A receiver located in the focal point of a satellite dish.

96 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Field –One scan of 262 1/2 lines. Fine-tuning –Slightly changes the frequency of the oscillator to provide the best response for an incoming signal.

97 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary FM audio detector –Detects the frequency variations in the modulated signal and converts them to an audio signal. Focal point –The small point in a satellite dish that receives signals.

98 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Frame –One set of the odd- and even-numbered fields in a scanning pattern. Frame rate –The number of times per second an image is updated on a video display screen. Currently, three frame rates exist: 60, 30, and 24 frames per second.

99 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Front end –In a television, the RF amp, mixer, and oscillator combined into one unit. Also called the tuner. Geostationary orbit –An object in orbit above, and rotating at the same speed as, the earth.

100 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary High definition television (HDTV) –Any television system capable of transmitting a picture resolution greater than 525 lines per screen. High voltage rectifier –Rectifies the high ac voltage developed by the horizontal output transformer in a television receiver.

101 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Horizontal AFC –In a television receiver, the horizontal oscillator frequency is compared to the sync pulse frequency. If they are not the same, voltages are developed that change the horizontal oscillator to the same frequency.

102 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Horizontal hold –In older televisions, the control that makes slight horizontal adjustments so the oscillators can lock in with the sync pulses. Horizontal oscillator –Provides the sawtooth waveform needed for horizontal scanning in a television receiver.

103 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Horizontal output –Correctly shapes the sawtooth waveform for the horizontal deflection coils in a television receiver. Also drives the horizontal deflection coils and provides power for the high-voltage rectifier.

104 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Horizontal output transformer (HOT) –Shocked by the output of the horizontal oscillator, this autotransformer develops high ac voltage in a television receiver. In-line –Type of gun assembly that followed the shadow mask tube, having different types of apertures available.

105 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Liquid crystal display (LCD) –1. A digital or alphanumeric display unit that can be used in visual outputs. 2. A type of display that operates on the principle of polarized light passing through tiny crystals of liquid.

106 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Mixer –Stage of television receiver during which the incoming video signal is mixed with the signal from an oscillator to produce an intermediate frequency.

107 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary MPEG2 –An image compression standard, developed by the Moving Picture Experts Group, used to increase the amount of video data that can be transmitted in an HDTV system.

108 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Multicasting –A digital broadcasting technique that allows, not only for multiple channels to be broadcast, but also for two to four channels to be broadcast in the same single-channel bandwidth.

109 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary National Television Standards Committee (NTSC) –A committee that formulated the standards for analog television and video in the United States. The NTSC standard calls for 525 scan lines at a 60 Hz refresh-rate, based on the interlace technique. NTSC is not compatible with most computer video systems and must be converted before it can be displayed.

110 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Passive-matrix –A type of liquid crystal display that has a grid of semitransparent conductors running to each crystal used as part of the individual pixel. Picture element –A small area or dot of varying intensity from black to white that contains part of the visual image of a scene.

111 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Pixel –The smallest unit used to designate an area on a graphic display. PIX-IF amplifier –Amplifies the output of the mixer stage.

112 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Polarized light –A filtered light consisting of light waves that are the same shape and of a single frequency, rather than the entire spectrum of light.

113 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Progressive scanning –A method of constructing an image of a display by capturing and transmitting the entire image at one time. With this method, each line is placed on the screen progressively in one sweep, rather than in two sweeps, as in interlaced scanning.

114 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Raster –Area of light produced on the screen of a television picture tube by an electron beam. Contains no picture information. Resolution –A measurement, in pixels, of the quality of an image. The higher the resolution, the higher the quality or more detailed the image.

115 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary RF amplifier –Used to amplify radio frequencies. Scanning –Sweeping an electron beam across each element of a picture in successive order to reproduce the total picture in television.

116 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Shadow mask picture tube –First type of color television, using a focus electron gun and a thin sheet of perforated material placed directly behind the viewing screen. Sound IF amplifier –Where an FM sound signal is amplified in a television receiver.

117 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Sync amplifier –A voltage amplifier stage that increases the sync pulses in a television receiver. Sync separator –A circuit that removes the horizontal and vertical sync pulses transmitted as part of the composite video signal in a television receiver.

118 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Synchronization (sync) pulse –Used to trigger an oscillator or a circuit. Thin film transistor liquid crystal display (TFT-LCD) –Most common type of display that consists of a matrix of thin film transistors spread across the entire screen.

119 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Tuner –The RF amp, mixer, and oscillator combined in one unit. Ultra high frequency (UHF) –Television frequencies that cover channels 14 to 83.

120 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Vertical hold –In older televisions, the control that makes slight vertical adjustments so the oscillators can lock in with the sync pulses. Vertical oscillator –Receives the output of the sync amplifier through a vertical integration network in a television receiver.

121 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Vertical output –Refers to the amplifier used by the output of the oscillator to provide the proper currents in the deflection yoke for vertical scanning in a television receiver. Very high frequency (VHF) –Television frequencies that cover channels 2 to 13.

122 © Goodheart-Willcox Co., Inc.Permission granted to reproduce for educational use only. Glossary Video amplifier –Used to amplify video frequencies. Video detector –Receives the output from the last intermediate frequency stage in a television receiver. Video head –A tiny electromagnet in a VCR that reads information from the recorded tape during playback.


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