Television (television/video): short for color television, the method of using electricity to transmit activities in real timevisionImage.withfilmSimilarly, TV makes use of the visual residual effect of the human eye to show the gradual static of one frameimageTo form a visually active image.The transmitter of the television system converts the fine parts of the scene into electrical signals according to brightness and chromadelivery。At the receiving end, display thebrightnessandchromaTo reproduce the entire original image.Simply put, it's a color TV.
Television is not the invention of any one person, it is the common crystallization of a large group of people in different historical periods and countries.As early as the 19th century, people began to discuss and explore the method of transforming images into electronic signals.In 1900, the word "television" already appeared.
People usually refer to October 2, 1925scotsmanIn an experiment in London, John Logie Baird "scanned" the image of a puppet as a sign of the birth of television. He is called "the father of television".However, this view is controversial.Because it was also that year that Vladimir Zworykin, an American, showed his TV system to his boss at Westinghouse.
Although the time is the same, the television systems of John Logie Baird and Vladimir Zworykin are very different.Historically, John Logie Baird's television system is called mechanical television, while Sfrogin's system is calledElectronicTelevision.This difference is mainly due to the different transmission and reception principles.
The development of television is complicated.Almost at the same time, many people were doing the same research.
Color TV
RCA launched the world's first set in 1939Black and white TVIn 1953, the national color TV standard was set and the RCA color TV was launched in 1954.
domestic
In 2012, TCL's annual shipment of color TV sets exceeded 15 million sets, which will directly lead to the pattern differentiation of China's color TV industry. China's color TV industry will form a new "wild goose pattern", that is, a new matrix of wild goose head, wild goose middle and wild goose tail with 15 million sets of enterprises as the first echelon, 10 million sets of enterprises as the second echelon and 7 million sets of lower echelons as the third echelon.
Analysis shows that there is a huge market gap of about 5 million sets between the first camp and the second camp of China's color TV industry, which puts TCL at the top of the industry.Industry observers who hold the same view believe that the market volume gap between the three echelons of the "wild goose pattern" will be further enlarged in the future due to the Matthew effect. In 2013, the trend of the stronger and the weaker in the household appliance industry will become more obvious.
History
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brief history
Christmas 1883
Nipkov, a German electrical engineer, used the "Nipkov disk" invented by him to make the first experiment of transmitting images using mechanical scanning method.Each picture has 24 lines, and the image is quite blurry.
1908
Kempel Swinton of England and Roshenk of Russia did not put forward the principle of electronic scanning, which laid the theoretical foundation of modern electrical technology.
1923
Soviet AmericanWaliGoldamine electrostatic storage camera tube.In the same year, he invented the electronic scanning picture tube, which is the pioneer of modern television photography.
1925
John Rocky Baird of England, according to“Nipkov disk”New research work has been carried out, and the mechanical scanning television camera and receiver have been invented.At that time, the image resolution was only 30 lines, the scanner could only scan the scanning area five times per second, and the image itself was only 2 inches high and one inch wide.He gave a performance to the public in a big shop in London.
1926
Baird gave a television broadcast and reception performance to the British press.
1927-1929
Baird passedTelephone cableThe first electromechanical TV trial broadcast;First short wave TV test;bbcStart to broadcast TV programs continuously for a long time.
1930
Realize simultaneous transmission of TV image and sound.
1931
It is the first time to put the film on the television screen——In London, people watched the live broadcast of the famous local horse race in Britain on TV——The United States has invented 25 images per secondElectronic tubeTelevision installation.
1936
The BBC uses Baird electromechanical television broadcasting, which is the first time to broadcastdefinitionTV image in practical stage.
Digital technology is used in TV broadcasting, and the experiment proves thatdigital television It can be used for satellite communication.
1976
The UK has completed the research on the "TV Library" system. Users can check news, books, newspapers or magazines directly with TV.
1977
Britain developed the first portable TV sets.
1979
The world's first "cable TV" was opened in London.It was invented by the British Post Office.It can transmit the information in the computer through ordinary telephone lines and display it on the user's TV screen.
1981
JapanSony CorporationA pocket black and white TV with a 2.5 inch LCD screen powered by batteries has been developed.
1984
JapanPanasonicThe company launched "Cosmic TV".The image of the system is 3.6 meters wide and 4.62 meters high, equivalent to 210 inches. It can be placed on large trucks and played in the streets and squares.The system adopts the "high brightness color light-emitting tube" exclusively developed by Panasonic, so that even in the daytime, bright and bright images can be obtained outdoors.
March 17, 1985
Tsukuba Science in JapanWorld ExpositionThe super large screen color built by SonyTV wallAppear.It is located on the central square, 40 meters long, 25 meters high, and covers an area of 1000 square meters. The whole building is as tall as a 14 story building.It's equivalent to a 1857 inch color TV.The super large screen consists of 36 large light-emitting screens, each weighing 1 ton, 1.8 meters thick, 4 lines and 9 works, with a total of 450000 color light-emitting elements.Through the camera installed on the top, various activities on the venue can be displayed at any time, and various advertising videos of Sony can be played.
1985
BT launched an integrated digital communications network.It provides users with voice, fast chart transmission, faxSlow scanning televisionTerminal, etc.
November 25, 1991
Sony of JapanHDTVTrial broadcast: 1125 scanning lines, twice as many as 525, and the image quality is improved by 100%;The aspect ratio of the screen has changed from the traditional 9:12 to 9:16, enhancing the audience's sense of the scene;The flat plane viewing angle is expanded from 10 degrees to 30 degrees, and the mapping has a deeper sense of depth;The "picture elements" of TV surface images have increased from 280000 to 1.27 million pictures per unit area, and the amount of information has increased nearly four times at a time... Therefore, the distance to watch high-definition TV is not 7 times but 3 times the screen height in the past, and the sound is lifelike. It uses 4-channel high fidelity stereo, which is very appealing.
1995
Sony Corporation of Japan launched a subminiature color TV receiver (i.e. palm type color TV), which is only the size of the palm and weighs 280g.It is equipped with speakers and headphone jacks. The LCD screen is about 5.5 cm. Although the picture looks small, the image is clear. Its most obvious feature is that people's body is used as an antenna to obtain the viewing effect. When watching TV, two wires are put around the neck to achieve the effect of an outdoor antenna.
1996
JapanSonyThe company launched the "wall mounted" TV to the market: it is 60cm long and 38cm wide, but only 3.7cm thick and only 1.7kg in weight, just like a mural.
The standard PAL color TV is mainly composed of five parts: power circuit, public channel, audio channel, color decoding circuit and color image display system.
(1) Power circuit
The power supply of color TV (hereinafter referred to as switching power supply) is composed of rectifier filter circuit, switching oscillation circuit, automatic voltage stabilizing circuit and voltage output circuit. Its main characteristics are small size, light weight, wide voltage stabilizing range, low power consumption, high efficiency and good reliability.
The power circuit is used to provide the DC voltage required for the normal operation of all parts of the TV set, and can maintain a stable DC voltage output when the grid voltage fluctuates and the load changes.
(2) Public access
The common channel is used to receive and amplify the radio frequency television signals (including color image signals and audio signals) transmitted by the television station (transmitting end)IF amplifier, video detector, etc.
(3) Sound channel
The audio channel is used to demodulate and amplify the audio signal and replay the TV audio. It is composed of audio amplifier, frequency discriminator, audio amplifier and loudspeaker.
(4) Color decoding circuit
The color decoding circuit is mainly used to demodulate and restore three primary color signals (or three color difference signals) from the color full TV signal, which is composed of brightness channel (brightness amplification, brightness delay), chrominance channel (band-pass amplification, ACC, comb filter, etc.), color subcarrier recovery circuit (color synchronization gating, subcarrier oscillation, etc.), matrix circuit, etc.
(5) Color image display system
The color image display system is composed ofLine scan circuit, field scanning circuit, color picture tube and its auxiliary circuit.The color picture tube is used to re display the color image.The function of the line and field scanning circuit is to provide deflection current with sufficient power for the deflection coil, and the line scanning circuit also provides the working voltage of each electrode for the picture tube (including anode high voltage, focusing electrode voltage, accelerating electrode voltage, etc.).The accessory circuit of the picture tube includes automatic degaussing circuit and pillow distortion correction circuit, etc. The function of the automatic degaussing circuit is to degaussing the picture tube every time it is turned on.The pincushion distortion correction circuit is used to compensate and correct the horizontal distortion of the grating.
Principles of Television
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Operating principle of color TV
The sequential sampling, transmission and reproduction of TV signals from point to plane are accomplished by scanning.The TV scanning system varies from country to country, with 25 frames per second and 625 lines per frame in China.Each line is scanned from left to right, and each frame is divided into odd lines and even lines by interlacing from top to bottom, so as to reduce flickering sensation.Transmission during scanningimage information 。When scanningelectron beamThe reverse scan line from the end of the previous line of forward travel to the starting point of the next line, and the reverse scan line from top to bottom of each field, which returns to the upper field, shall be hidden.Transfer during line field blankingField synchronization signalTo synchronize the scanning of the receiving and sending, so as to accurately reproduce the original image.TV cameraIt focuses the light image of the scene on the photosensitive (or photoconductive) target surface of the camera tubephotoelectronThe change of excitation or photoconductivity varies with the brightness of each point of the light image.When an electron beam is used to scan the target surface, an electrical signal whose amplitude is proportional to the brightness of the light image of each point is generated.Transmit to TV receiver to makeKinescopeThe scanning electron beam of the screen changes with the strength of the input signal.When scanning synchronously with the transmitting end, the transmitted original image will appear on the screen of the picture tube.
The process of TV signal transmission and distribution, taking the live broadcast in other cities as an example, generally starts from the camera, TV center or relay vehicle, then through the microwave trunk line, transmission station, and finally to the user TV receiver.In addition, TV broadcast satellite and cable TV are also effective means for national and urban regional TV transmission and distribution.
TV frequency band
The scanning system of TV signals in different countries is not the same as the channel broadbandInternational Radio Consultative Committee(CCIR) is distinguished by Latin letters.For example, M represents 30 frames per second, 525 lines per frame, and the video bandwidth is 4.2 MHz. The total high frequency bandwidth of the lower sideband, plus FM audio and AM video, is 6 MHz;D. K stands for 25 frames per second, 625 lines per frame, 6 MHz video bandwidth and 8 MHz high-frequency bandwidth.The video baseband'sFull TV signalModulated to VHF or UHF together with audio signalFrequency bandBroadcast transmission on the.
Internationally, the frequency bands for television broadcasting include I and III bands in VHF, and IV and V bands in UHF.TV channel is the nominal channel position occupied by the frequency of a certain channel of TV broadcasting.Different countries adopt different television standards and channel division.In China, I band is 48.5-92 MHz, divided into channels 1-5;Band III is 167 ～ 215 MHz, divided into channels 6 ～ 12 (Table 1).Ⅳ band 470~566Megahertz, divided into channels 13 to 24;The V band is 606-958 MHz, divided into 25-68 channels.The frequency interval occupied by each channel is fixed.The Chinese 625 line 25 frame D, K standard is shown in Figure 1, in which the image signal modulates the image carrier frequency fp to maintain low frequencyphaseAnd adopt the form of residual sideband.The image signal frequency band after partial suppression of the lower sideband is -0.75~+6 MHz relative to fp. The accompanying sound signal modulates the accompanying sound carrier frequency fs, which is 6.5 MHz higher than the image carrier frequency. The modulated accompanying soundsignal frequency The range is ± 0.25 MHz relative to fs.So each TV channel occupies 8 MHzfrequency range 。
TV system
Except including the same asblack-and-white televisionIn addition to the standard contents distinguished by Latin letters, such as scanning and channelcolour television system 。The broadcast color TV system is required to be compatible with black and white TV, that is, black and white TV can receive color TV broadcast, and color TV can also receive black and white TV broadcast, but all received are black and white images and accompanying sound.For this reason, color TV is based on the principle that a certain proportion of the three primary colors in the additive color mixing method can be mixed into various colored lights, including white light. At the same time, in order to be compatible with and compress the transmission band, red (R), green (G), blue (B) three primary color signals are generally composed of brightness signal (Y) and blue and redChromatic aberration signal(B-Y), (R-Y), where the brightness signal can be used to transmit black and white images,chromatic aberrationSignals andbrightnessThe combination of signals can restore the three primary color signals of red, green and blue.Therefore, in addition to transmitting the brightness signal and accompanying sound signal that are the same as those of black and white TV, compatible color TV also transmits chrominance signals simultaneously in the same video frequency band.Chromaticity signal is composed of two color difference signals modulating the color subcarrier at the high frequency end of the video frequency band.In order to prevent the modulation overload of color difference signals, the blue and red difference signals (B-Y) and (R-Y) are compressed, and the compressed blue and red difference signals are represented by U and V.
A compatible color for the official broadcast of the United States in 1954TV systemIt is also used in Canada, Japan and other countries.NTSC is the abbreviation of the National Television System Committee.This system distinguishes blueMagentaThe visual characteristic with the weakest ability to distinguish color details between red and yellow, and the strongest ability to distinguish color details between red and yellow, uses the color difference signal Q between blue and magenta and the color difference signal I between red and yellow to replace the blue and red difference signals U and V.Two color subcarriers of the same frequency with initial phase angles of 33 ° and 123 ° are respectively modulated with Q and I color difference signals for orthogonal balance amplitude modulation to facilitate decoding, separation and suppression of subcarriers. The modulated two color difference signals are mixed to form a chrominance signal.In order to synchronously detect the chrominance signal at the receiving end, it is necessary to send excellent signals during line blanking at the transmitting endSynchronizing signal。This system is characterized by simple decoding circuit and low cost.
1963Federal GermanyA system developed to reduce the phase sensitivity of the NTSC system. It was officially broadcast in 1967 and is also used in Britain, China and other countries.PAL is an abbreviation for Phase AlternationLine.This system uses U and V color difference signals toInitial phasePerform quadrature balance AM for two color subcarriers of the same frequency at 0 ° and 90 °, and invert the color difference signal of the V component line by line.In this way, the phase deviation of the chrominance signal is averaged between adjacent lines and is offset.This system is not very sensitive to phase deviation, and it is less affected by multi-path reception in transmission.
It was officially broadcast in France in 1967. It is also a compatible color TV system developed to improve the phase sensitivity of the NTSC system. It is also used in the Soviet Union and some Eastern European countries.SECAM is the abbreviation of S é sequential Couleur à M é moire, which means that when luminance and chrominance signals are transmitted at the same time, the sending end transmits red and blue difference signals line by line.However, when decoding at the receiving end, it is necessary to have luminance and red and blue difference signals at the same time to restore red, green and blue primary color signals. Therefore, in the receiving decoder, a delay line is used to store one of the received color difference signals for one line of time, and then three signals for decoding are formed together with the luminance received at the next line (one line has been delayed at the sending end) and another color difference signal.Chromaticity signal is composed of red and blue color difference signals tuned to two color subcarriers with a certain frequency interval.The characteristic of this system is that it is less affected by multi-path reception in transmission.
TV signal
A composite signal that transmits images in the baseband of television video.The full TV signal of black and white TV includes: line (horizontal), field (vertical) scanning synchronization and blanking signal during scanning reverse travel, and black and white brightness signal of scanning forward travel time.The synchronization signal synchronizes the scanning of the transmitter and receiver to ensure the stable reproduction of the received image;The blanking signal is used to eliminate the interference of the bright line in the flyback;Black and white brightness signal is used for black and white or color TV to receive black and white TV images.The full TV signal of color TV (Figure 2) has the same content as black and white TV, but also the color synchronization signal and chroma signal.The color synchronization signal is transmitted during the reverse scanning. In the NTSC system and PAL system, it provides the frequency and phase reference of the color subcarrier required by the receiving decoder. In the SECAM system, it serves as the line order identification signal.Chromaticity signal is transmitted simultaneously with black and white brightness signal during the scanning process, which occupies a small part of the high-frequency end of the video baseband.After demodulation, two color difference signals are obtained. Black and white brightness signals occupy most of the video baseband above the low frequency. In addition to black and white TV receiving black and white images, they also enter the matrix network together with two color difference signals to restoreReddening, green and blue primary color signals, amplified and sent toColor kinescopeDisplays a color image.
The main advantage is that they are quite thin, can be hung on the wall to watch, and their display screens can be very large (the plasma in the market can reach more than 60 inches, and the liquid crystal can reach more than 55 inches).After the technological development in recent years, the price has dropped significantly, and the display effect and clarity have made a qualitative leap. It has become quite popular and is the mainstream in the market.In addition, the TV with Android operating system is no longer just watching programs passively, integrating Internet access and rich applications, and realizing human-computer interaction through camera and somatosensory technologyIntelligent mobile phoneBelong toIntelligent terminalOne of.
CRT
(Only digital high-definition is mentioned here): The main advantage is that all aspects are excellent (high brightness and contrast, large viewing angle, fast response speed, and good color restoration), but the largest screen is only about 34 inches, and it is very thick and bulky, which also consumes power.29 inch and 34 inchCRT TVThe products that basically belong to this phase out have been discontinued, and they can be seen on the market are all previous inventories.
Rear projection
(CRT rear projection, DLP rear projection, LCOS rear projection, LCD rear projection): Traditional CRT rear projection has become less popular, and the market has been snatched by digital rear projection (DLP rear projection, LCOS rear projection, LCD rear projection).DLPThe light display rear projection is popular because it can be said to be a real digital TV, which performs well in all aspects. The screen is bigger and the size is smaller (we have said its imaging principle many times, welcome to the Xinbao website to find the answer). It is the most popular one.The LCD rear projection is slightly inferior due to its high heating capacity and short lamp life.
Projection television
In fact, it is the civilian version of the projector that we see in the company's conference room. It is usually installed at home and can be used to watch movies.
Manufacturing development
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In 1958, China's first black and white TV set, the Beijing brand 14 inch black and white TV set, was born in Tianjin 712 Factory.
On December 26, 1970, China's first color TV set was born in the same place, which marked the beginning of China's color TV production.
In 1978, the state approved the introduction of the first color TV production line, which was located in the former Shanghai TV FactorySARFTGroup.It was completed and put into operation in October 1982.Soon, Xianyang Rainbow Factory, the first color tube factory in China, was established.During this period, China's color TV industry was rapidly warming up and quickly formed a scale. More than 100 large and small color TV production lines were introduced nationwide, and pandasVenus, peony, Feiyue and a large number of domestic brands.
In 1985, China's TV production reached 16.63 million sets, surpassing the United States, only second to Japan, and becoming the second largest TV producer in the world.However, due to the constraints of structure, price, consumption capacity and other conditions in China's TV market, the TV penetration rate is still very low, with only 17.2 and 0.8 TV sets per 100 households in urban and rural areas respectively.
In 1987, China's TV production reached 19.34 million sets, surpassing Japan and becoming the world's largest TV producer.
From 1985 to 1993, China's color TV market realized a large-scale upgrade from black and white TV to color TV.
In 1993, TCL launched the "TCL Ace" in the first half of the yearLarge screen color TVThe market price of 29 inch color TV is about 6000 yuan, and more than 100000 sets have been sold by the end of the year.
In March 1996,ChanghongThe first large-scale price reduction declaration was issued to the whole country - reducing the price of color TV sets by 8% to 18%. Two months later,KonkaSubsequently, it followed up and launched an unprecedented price war in the history of the color TV industry.In April of that year, Changhong's sales jumped to the top of the market, and domestic brands captured a large number of market shares of foreign brands through price war.The price reduction war also led to a major reshuffle of the entire Chinese color TV industry, and dozens of color TV manufacturers withdrew from the market.
In 1999, consumer gradePlasma TV Appear in domestic shopping malls.At that time, the price of 40 inch plasma color TV was more than 100000 yuan.
In 2001, China's color TV industry suffered a large loss. KonkaXocecoGao Luhua lost money and Changhong's profit per share was only 1 cent. This situation was not reversed until 2002 through technical improvement.
In 2002, Changhong announced that it had successfully developed China's first LCD TV with the largest screen.Its screen size greatly exceeded the traditional industry limit of 22 inches, reaching 30 inches, and was known as the "first screen in China" at that time.
In 2002, TCL launchedPlasma TV"Popularization storm" opened the door for plasma TV to go to consumer families.HisenseFollow up immediately.
In April 2003,Ni RunfengThe popularization plan of rear projection was launched, and the maximum decline of rear projection TV was 40%.
In 2004, the United States began to implement anti-dumping measures against Chinese color TV sets, which led to the inability of Chinese color TV sets to enter the American market directly.
In 2004, the total sales volume of color TV sets in China was 35 million, of which the sales volume of flat screen TV sets was only 400000, accounting for 1.14% of the total color TV sets.
Since October 2004, the sales volume of flat screen TV in several major cities in China has exceeded that of traditional TV for the first timeCRT(Analog) color TV.
In the first half of 2005, the sales volume of China's flat panel color TV sets reached 725000, up 260% year on year;The ownership rate of LCD TVs and plasma TVs in urban households reached 3.56% and 2.81% respectively.
The 1973 snail event delayed Chinese people to watch color TV for five years
In order to "more realistically reflect the glorious image of leading comrades", the State Council approved the introduction of a color TV production line in 1972Corning CorporationThe Americans sent each member of the delegation a beautiful snail before returning home.After receiving the secret report, Jiang Qing lost his temper at the Fourth Engine Department and said, "This is a provocation from the US imperialism, and how dare he slander us as crawlists". He instructed the Ministry of Foreign Affairs to send a note to the US Liaison Office in China to protest and send the snail back!According to the investigation of the China Liaison Office in the United States, snails are traditional Christmas gifts in the West, meaning good luck, without the concept of speed;The Americans didn't mean to satirize China, they just wanted to please us and hope that we would buy their technology.Although the Politburo of the CPC Central Committee decided to withdraw Jiang Qing's speech at the SJ Petroleum Machinery Department, under Jiang Qing's pressure, it was impossible to import color TV production lines from the United States as planned, so it had to wait another five years and spend nearly 90 million dollars more to import them from Japan.For a false political reason, the Chinese people delayed five years to see color TV sets, and also sent about 700 million yuan of taxpayers to Japan.As a result, China's color TV sets have also gone to the Japanese P format, rather than the American N format.
In the first half of 2017, the retail volume of domestic color TV sets was 21.81 million, down 7.3% year on year;Retail sales reached 74 billion yuan, up 4.3% year on year.As the price increase of panel is higher than that of the whole machine, the profits of color TV enterprises have generally declined, and the industry's net profit is estimated to be less than 1%, which is lower than the level of about 1.5% in the same period last year. "In June this year, the average price of 4KUHD panel, the 55 inch TV with the largest sales volume, increased by 19% year on year, but the average price of the whole machine decreased by 1.5%;The average price of HD panel of the 32 inch TV, the second largest in sales, increased by 26% year on year, while the average price of the whole machine only increased by 13%.[1]
Screen size
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Generally speaking, the 32 inch LCD TV and the 42 inch LCD TV are 32 inches. 42 inches is the screen size of the TV.The screen size of a TV is a parameter that measures the maximum possible display picture of the TV. It is measured by the length of the diagonal of the TV screen, usually in inches.
LCD TV screen size characteristics
LCD TV screen size is strictProduct specificationBecause the LCD screen is not covered by the frame.
LCD TV screen is short of weight
The size of some products sold in the market is not true, which is mainly shown as 1-2 cm less than the marked standard size, that is, less than 1 inch.
Current situation and prospect
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present situation
Television is undergoing a revolution.Current situation of television technology: one of the most obvious characteristics of current television technology is digitalization.The first is digital program production.In the late 1990s, the BBC（BBC）First established in the world“Columbus”System.This system makes the storage, editing and broadcasting of BBC TV programs fully digital, that is, non tape, which greatly improves the working efficiency of BBC and saves production costs.In addition, TV organizations are gradually eliminating traditionalAnalog cameraandVideo tape, replaced by digital cameras and various emerging recording carriers.This change has greatly improved the quality of images.Secondly, the transmission technology is also diversified.In addition to the traditional wireless microwave transmission, there are cable TV, satellite TV and other transmission methods.These new transmission methods effectively reduce the inevitable attenuation of signals in the transmission process, and ensure better reception quality.The last is the digital transformation of receiving technology.The improvement of sound and picture quality and two-way interaction are the two greatest benefits brought by the widespread promotion of digitalization.
The rapid development of TV media has made people more confused.The polarization of TV media is serious, and well-known TV sets such as BBC and CNN have powerfuldiscourse powerThe degree of specialization is strengthened, and the audience is more narrow.
prospect
TV program productionThere are two directions to go.One is more realistic.That is, restore the event itself more realistically.For example, a large number of live broadcast applications of CNN in news events are one of them.The other is more dramatic. For example, FOX NEWS, which is opposite to CNN, uses a lot of dramatic language in its programs to "exaggerate" the U.SIraqThe war.Of course, these two directions are just two different directions of program production, which have always existed.Only the features are more prominent.In addition, the narrow broadcast of programsChannel specializationEtc.
At the same time, in today's increasingly advanced technology, television is being used more and more by the country as a tool.Because the current national strength is no longer limited to the traditional "hard" power such as economy and military.Soft power such as culture should also be considered.Therefore, television is considered a good tool to enhance a country's soft power.This trend is intensifying.
Television is a technology and a culture.Its cultural level is confronted with otherEmerging media(such as the Internet), the influence will inevitably decline like the previous films and dramas.However, TV as a technology will have great development.TV technology will be more widely combined with other technologies in the future, so as to fully facilitate people's life.For example, the combination of TV technology and mobile communication technology makesmobile TV The delivery ofNorwayIt is possible.The British Broadcasting Corporation (BBC) organically combined television technology with the Internet a few years ago, turning its core website, BBCi, into a huge video database, making it a leader in the world's media in terms of interactive ability.
How to choose
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1、 Ordinary TV:
1. Channels: Generally, the number of preset channels should be more than 50.
2. Images: Generally, TV sets broadcast 50 images every second. At this speed, the naked eye looks flickering, and the eyes will get tired after a long time.While the 100Hz digital color TVdigital signal processing 100 images will be broadcast in one second, which will greatly reduce the flicker of images. The images will be clear, stable and smooth. Even if you watch TV for a long time, you will not feel tired. It is an environmentally friendly product. Users with economic conditions should try to consider it.
3. Picture: Flat screen color TV is another hot spot in the recent market.The advantage is that no matter what angle you watch the program from,Image distortionCan be minimized,Image contrastHigh, clearer picture level and more bright colors can greatly reduce the reflection of ambient light on the screen.
4. Purpose: The multimedia color TV set launched in the market can be connected to the computer.Without changing the existing working mode of the TV, it uses digital storage and scanning technology to convert computer image signals into TV image signals, which are displayed on the TV screen, making the TV a large screen display.
5. Voice: There are many kinds of color TV sets with the functions of Liyin, but only those that conform to Chinese standards are more suitable for Chinese consumers.The effective system of Chinese Liyin includes Hong Kong PAL and Mainland PAL-D.
2、 Rear projection TV shopping:
1. The function and movement quality should be considered first when selecting rear projection color TV sets. The advancement of movement technology has a decisive impact on image quality.
2. The definition of rear projection TV should be at least 500 lines. Try to buy projection TV with high illumination.
3. The angle of view of rear projection TV is smaller than that of ordinary picture tube TV, so its angle of view and brightness are very important when purchasing.
4. The image is mainly divided into brightness, noise point and chroma.First, adjust the brightness of the rear projection color TV from dark to bright. It is better to avoid obvious color deviation. If there is color deviation, it indicates that the cathode of the color TV is unbalanced.Secondly, look at the noise points without signal input. The more, smaller and rounder the noise points are, the higher the sensitivity of this rear projection color TV is.
5. Chromaticity: When the chromaticity is adjusted to the minimum, the image should be black and white. When the chromaticity is adjusted to the maximum, the color should be rich. When the chromaticity is adjusted to the appropriate position, the skin color of the person should be normal, the level should be obvious, and there should be no accumulation of large color blocks.
6. Voice: adjust the volume potentiometer to a higher or lower level. It is better to have a soft and loud voice with obvious changes in the volume potentiometer. There should be no hoarse and alternating sounds.
3、 During inspection, check whether the rear cover seal of projection screen box is intact.Because once the dust falls through the gap at the rear of the box to contaminate the lens and screen, the image quality will decline. Another key point is to see whether the screen has scratches and defects. Because the screen of the projection TV is not made of hard glass, but made of plastic organic cloth, which is very easy to scratch. Once there is a scratch, it can't be repaired, but only replace the screen.Do not wipe the screen with alcohol or other solvents to avoid damage to the screen. Do not put anything on the top of the TV to prevent deformation of the TV case and screen.
Finally, try to be earthquake resistant.By tapping the rear projection color TV case with your hand, the rear projection with no flash, no bounce and no abnormal sound has good shock resistance, otherwise it is poor.
Maintenance
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maintain
1. When there is abnormal sound or smell in the machine, please immediately turn off the power supply and unplug the plug. If it is confirmed that it is abnormal, please do not continue to use itprofessionaloverhaul.
2. If you go out for a long time or do not watch TV for a long time, you must turn off the TV and unplug the power plug,thunderstormAlso disconnect the machine from the antenna during the season.
3. You can't watch TV in thunderstorm.Unplug the power plug and antenna before the thunderstorm to prevent lightning strike.According to the national "three guarantees" regulations, the lightning strike machine belongs to the scope of non free warranty machine.
4. Do not place flammable and explosive materials on the TV cover. Candles, electric stoves, light bulbs, etc. cannot be placed on or near the machine to avoid accidents.
5. Be careful of liquid and metal entering the TV body.If any liquid or metal falls into the machine, it must not be turned on again for use. It should be handled by professional personnel as soon as possible.
6. Not availableChemical ReagentsWipe the machine.The solvent may deteriorate the housing and damage its painted surface.If there is dust and dirt, you should turn off the TV for ten minutes and then use a wet cloth to wring it dry and wipe it. The fluorescent screen can be wiped with a clean soft cloth.
7. Dust proof fluorescent screen must not be wiped.The dust-proof fluorescent screen will automatically prevent dust contamination. If there is a little dust or dirt, you can gently wipe it with soft silk instead of wiping it.
maintain
1. Always adjust the position of the program to avoid premature failure of the channel key switch.
2. Do not pull or plug the cable plug with force to preventTunerOr the circuit is damaged.
3. Use lessRemote controlTurn on and off the main power supply.
4. In thunderstorm weather, not only the antenna plug but also the power plug should be unplugged to prevent lightning strikes.
5. Pay attention to the influence of magnetic field to prevent the TV from being magnetized.
6. Place your TV flat to prevent the circuit board inside the machine from deformation and damage.
7. Pay attention to the heat dissipation of the TV to prevent components from overheating and damage.
8. Pay attention to eliminate some hidden dangers in use, and avoid metal foreign matters falling into the TV, such as pins, paper clips, small nails, coins.
9. Avoid water entering the machine, and keep the TV away from water pots, flower pots, tea cups, water heaters and other items.
10. Coal burning families should pay attention to the corrosion of soot on TV sets.
11. The remote control should be wrapped in a transparent plastic bag and prevented from falling to the ground.
stayLCD TVThe only part that is gradually consumed is the backlight of the display.After long-term use, you will find that the screen becomes dim or simply does not light up. In these two cases, as long as you replace the backlight, you can bring the LCD TV back to life and become the same as the new one.
Internal burn out
Remember,CRT TVIt can burn out due to long-term work, as well as LCD TV.Therefore, you must remember to turn off the LCD TV when it is not in use, or the interior will burn out or age after a long time.Once such damage occurs, it is permanent and irretrievable.So we must pay enough attention to it.In addition, if a fixed content is continuously displayed for a long time, it may cause some LCD TV pixels to overheat, thus causing internal burning.
Maintain humidity
Do not allow anything with moisture properties to enter the LCD TV.If fog is found, gently wipe it off with a soft cloth before turning on the power.If the moisture has entered the LCD TV, it must be placed in a warm and dry place so that the moisture and organics can evaporate.Power on the liquid crystal television containing humidity can lead to corrosion of the liquid crystal electrode, thus causing permanent damage.
Screen surface
If dirt is found on the surface of the display screen, a little can be stainedGlass cleanerWipe it off gently with a soft cloth. Do not spray the cleaner directly on the surface of the display screen.Detergent entering LCD TV will cause screen short circuit.
Avoid vibration
LCD TVThe screen is very fragile, so avoid strong shock and vibration.LCD TV is almost the most sensitive electrical equipment of all products in the user's home or office.LCD contains a lot of glass and sensitive electrical components, which will cause LCD screen andCFL unitIs damaged.Also be careful not to apply pressure to the LCD display surface.
Do not disassemble
One rule is never to disassemble the LCD TV.Even after being turned off for a long time, the CFL converter in the backlight assembly may still have a high voltage of about 1000V, which can cause serious personal injury.Therefore, never attempt to disassemble or change the LCD display to avoid high voltage.Unauthorized maintenance and changes may cause the display screen to temporarily or even permanently fail to work.
Daily maintenance
1. Heat dissipation: The high temperature generated by high power can be regarded as the number one enemy of plasma TV, so pay special attention to the heat dissipation of plasma TV in use.
2. Screen burn: partial screen burns due to long playing of fixed still images, which is determined by the characteristics of plasma TV itself.
3. Voltage: If possible, an independent power supply line should be provided for the plasma TV, or it is also a good choice to add a stable power supply.
4. Cleaning: regularPlasma TVIt is also a good way to keep the screen quality by cleaning the screen and keeping the screen surface as bright as new.
5. Damp proof, dustproof and lightning protection: keep the working environment of the machine relatively dry, and do not let water enter the machine body;When the machine is not in use, dust cover can be considered;One for plasma and surrounding electrical appliancesLightning protection socketThat's all right.
How to maintain
1. Replace the battery in case of failure to avoidBattery leakagecorrosionCircuit board；
2. Do not allow water or other liquids to wet the remote control;
3. Please do not let children play with the remote control to avoid breaking it;
4. Never use solvents orStrong chemicalsWipe the surface of the remote control. If there is any slight dust, use a clean soft cloth or cotton yarn to gently remove the dust;If the surface dirt is serious, use a clean soft cloth or cotton yarn dipped in neutral detergent to remove the dirt and then dry it naturally.
Extended life
1. Prevent premature aging of the picture tube.The measure is that the brightness should not be turned on too bright when watching, and the TV should not be switched on and off frequently. Try to watch TV when the power supply is stable.Generally, the effective service life of the picture tube is more than 5000-10000 hours. If the picture tube is used for 3-5 hours every day, it is not a problem that the life of the picture tube is 5-10 years or even longer.
2. Pay attention to the heat dissipation and ventilation of the TV.Most of the parts inside the TV set will generate heat when they are working. If the heat dissipation effect is not good and the heat cannot be emitted in time, their temperature will become higher and higher, causing damage.In addition, if the TV has been used for a long time, please ask the maintenance personnel to remove the dust inside the machine.
3. TV sets that are seldom used are easy to be damaged. Especially in the rainy season, it is necessary to turn on the TV set frequently and use the heat emitted inside to remove the moisture inside the set.
Dust removal
Remote control
The TV has been used for a long time, and dust will appear on the screen due to electrostatic attraction. At this time, do not scrub it with chemical reagents (such as:alcohol）。In order to improve the picture effect of many TV sets, a layer of oxide protective film is coated on the screen surface.If it is wiped with chemical reagent, the protective film will be damaged and cause unnecessary loss.The best way is to use special screen wiping materials.If there is no special one, you can use napkin and soft cotton cloth to wipe gently, but be careful not to touch water.Suggestions: (1) The TV should not be switched on and off repeatedly without control, which will accelerate the aging and affect its service life.(2) Color TV is most afraid of strong magnetic field interference.Moving a magnetic object in front of the screen will cause the TV to be magnetized and color disorder. Pay special attention to the speakermagnetWait, don't put it near the TV.(3) The TV should be placed in a cool, dry and ventilated environment. A humid environment will increase the failure rate and shorten the service life of the TV.(4) When using, there should be a space of 5-10cm or more around the TV set, and pay attention to the ventilation holes around the housing.Turn off the TV and cool it down for a while before covering the TV to prevent dust.(5) After watching TV, it is better to switch on and off the power supply instead of using the remote control for convenience. The remote power off part is still working, which not only consumes electricity, but also can cause magnetic phenomenon after long-term remote power off.(6) In thunderstorm weather, it is better to unplug the power plug and antenna (or wired) plug to avoidthunderTo ensure the safe use of TV sets.(7) Pay attention to eliminate some hidden dangers in use, such as preventing metal foreign matters and liquids from falling into the TV, and do not put lighted candles on the TV.
Audience interaction
Announce
edit
TV is a real-time media, which cannot be reviewed or watched repeatedly unless recordedNetwork mediaIn this respect, it has obvious advantagesPrinting mediaIt can be viewed at any time, but also overcomes the shortcomings of poor timeliness, lack of classification and limited length, becoming a database andClassification informationlibrary.
Interaction isTelevision mediaIt has been exploring an important means to strengthen the connection between the communicator and the audience and understand the audience's response.The development of network technology enables people to have a deeper understanding of the word "interaction" and write it into the life of the audience and the media.The combination of TV and network is the best marriage.The network absorbs the content of TV, and TV really realizescommunication effect Optimization of.
IPTVInteractive IPTVIt is a new technology that uses broadband network infrastructure to provide users with video on demand, Internet access, e-mail, games and other interactive digital media personalized demand services, with computers (PCs) or "ordinary television+network set-top box (TV+IPSTB)" as the main terminal equipment.Network TV software based on P2P principle, but different from other P2P network TV, the server side function is open, allowing users to add their own programs, programs found on the Internet can also be added, and programs can also be added based on P2P principle propagation.
Teletext is a subsidiary service of television broadcasting.Teletext is onanalog televisionIn the system, the TV screen displays 25 frames of TV signals every second, 625 lines per frame, each line is scanned from the left to the right of the screen, and each frame is scanned from the top to the bottom in two fields.Of the 625 lines of each frame, only 575 lines are actually displayed on the screen, and 50 lines are reverse travel, which is invisible.In addition to transmitting test signals, reverse travel can also be used to transmit additional data information, including graphics and text.At the receiving end, the audience can receive and see the transmitted information on the screen by using a dedicated teletext decoder.
Video conference is a rising way of communication. The advent of video conference has greatly shortened the distance of face-to-face communication between people, changed the previous conference mode, not only saved human and financial resources, but also improved work efficiency.The video conference telephone system picks up images and sounds through the camera and converts them intodigital signal, and compress it before passingCommunication networkSend the signal out.The other party will receive the digital signaldecompression , revert toanalog signalThe whole process is basically "real-time".At present, the videoconference telephone system can only be held in China.
