History of live TV broadcast presentation. A television. What are TVs

Slide 1

Slide 2

Slide 3

Slide 4

Slide 5

Slide 6

Slide 7

Slide 8

Slide 9

In televisions, an image is formed from frames that change at a certain frequency, and each frame consists of a certain number of lines. It is known that the eye begins to distinguish flickering (frame changes), starting at a frequency of 41 Hz (with a white source brightness of 30 cd / m2). Therefore, the frame rate must be higher. In television broadcasting, each frame is transmitted in two fields, one of which contains all the odd lines, and the other contains all the even lines. In the world, there are basically two television scan standards: European at 625 lines at 25 frames per second and American at 525 lines at 30 frames per second. This uses interlaced decomposition with two fields per frame. These standards are technically and economically viable, but they are only sufficient for close-up images. When transferring images containing fine details, the clarity of the images drops dramatically. In addition, in an interlaced screen with two fields, interlaced flickering appears in the frame, due to the different brightness of the lines of successively reproduced fields. Viewing the TV is very tiring for the nervous system, because low image quality and a variety of flickering are perceived by the subconscious. T.N. The “green” standard for safe television broadcasting requires scanning at a frame rate of at least 90 frames per second. Another reason for the effect on the nervous system is the noise of the TV line generator. This frequency is about 16 kHz (at the limit of human hearing), however, with prolonged exposure it causes fatigue.

Slide 1

: “If the TV and the refrigerator were not in different rooms, then some of us would have died from lack of physical activity. »Stephen Patrick Morrissey

Slide 2

Slide 3

The invention of radio and cinema
Alexander Stepanovich Popov May 7, 1895 - radiotelegraph 1919 - transmission of the first sounding word

Slide 4

Cinematograph - Auguste and Louis Lumiere
1895 - the first movie camera

Slide 5

Nipkow disk 1884 (1923) first mechanical image scanning device
A rotating opaque disk, up to 50 cm in diameter, with holes drawn in an Archimedes spiral - ("electric telescope"). The image was scanned with a light beam based on one (!) Photocell with the subsequent transmission of the signal to a special converter. The number of holes was from 30 to 200. There was a neon lamp behind the disk.

Slide 6

Mechanical TV
The screen glowed with a pink light, until the 40s. - green The picture was blurred, in the form of shadows and contours, "mute" 1930. A television laboratory was created at the All-Union Electrotechnical Institute, two radio receivers were required to receive a television broadcast

Slide 7

Start of production of mechanical televisions
April 15, 1932 Pravda newspaper: "The Leningrad plant" Comintern "began to develop the first 20 Soviet TV sets of the" B-2 "brand with a screen size of 3x4 cm" The TV was connected to a broadcasting receiver instead of a loudspeaker.

Slide 8

First television broadcast
April 30, 1931 Pravda newspaper: “Tomorrow for the first time in the USSR there will be an experimental broadcast of television (far-sightedness) by radio. From the short-wave transmitter RVEI-1 of the All-Union Electrotechnical Institute at a wavelength of 56.6 meters, an image of a live face and photographs will be transmitted. ”More than 30 homemade TVs were operating in the capital
The construction of the Moscow Television Center had not yet been completed, and there was no roof over the pavilion, when the trial broadcasts of films began. The first took place on March 25, 1938 - the film "The Great Citizen" was shown. On September 5 of the same year, test studio broadcasts began. The Act on the completion of the construction of the Moscow Television Center was signed on December 31, 1938, and regular broadcasting began on March 10, 1939. The receiving network consisted of 100 TV sets installed within a radius of up to 30 km from the transmitter.

Slide 9

Cathode ray tube 1907
Boris Lvovich Rosing Lecturer at the St. Petersburg Institute of Technology The cathode tube was invented by the Englishman W. Crookes, improved by the German scientist K. Brown 1911 - "privilege No. 18076" for the world's first electronic television set 1912 - gold medal and prize named after an honorary member of the Russian technical society K.F.Siemens 1922 - state patent for "radio telescope"

Slide 10

The first electronic TV
1925 year. Swedish engineer John Byrd. The first transmission of recognizable human faces and the first television system capable of transmitting moving images. Late 1936. RCA American Research Laboratory. Vladimir Kozmich Zvorykin The very first electronic TV set suitable for practical use (iconoscope) 1939 the first TV set designed specifically for mass production. The RCS TT-5 is a massive wooden box with a 5-inch screen.

Slide 11

Soviet electronic TV
November 15, 1934 - the first broadcast with sound 1949 KVN 49 (Kenigson - Varshavsky - Nikolaevsky)

Slide 12

Development of television
1950 - 1st long wire remote control. 1954 RCA. The first color TV. Screen diagonal 15, 19, 21 inches. Price - $ 1000 1960 - First semiconductor TV. Firm SONI. 1967 - production of color TV sets in the USSR.

The first stages of television development For the first time the phenomenon of the photoelectric effect - the release of electrons by matter under the influence of electromagnetic radiation, was discovered by the German physicist Heinrich Hertz in 1887, and a year later the Russian scientist Alexander Stoletov conducted an experiment that clearly demonstrates this phenomenon. In 1907, the Russian physicist Boris Rosing was able to theoretically substantiate the possibility of obtaining an image using a cathode-ray tube, previously developed by the German physicist K. Brown, and even managed to put it into practice: he was able to obtain an image in the form of a single fixed point.

The first working television system is considered to be the invention of the German engineer Paul Nipkow, made back in 1884. The design laid the foundation for the creation of the so-called mechanical television. Paul Nipkow invented a disk with which the image was converted into electrical impulses. It was a disk with a certain number of holes arranged in a spiral, opposite which a photocell was installed, and the light entered the photocell through this disk.

A patent for an optomechanical device for decomposing an image into elements during transmission and reception of television signals, called the Nipkov disk, was obtained in 1884. Nipkov rotated the disk over a picture or object. The light pulses penetrating through the holes in the disk were converted by a photocell into electrical signals. Then the number of lines on the screen was small - about 300, that is, the light penetrated the object through three hundred holes, and the mechanically scanned television "picture" was rough.

Thanks to the Nipkow disk, in 1925 the Swedish engineer John Byrd was the first to achieve the transfer of recognizable human faces. Somewhat later, he also developed the first television system capable of transmitting moving images. At first, the development of television went in two directions - electronic and mechanical. Moreover, the development of mechanical systems took place almost until the end of the 40s of the XX century, before it was completely replaced by electronic devices. On the territory of the USSR, mechanical telesystems lasted a little longer.

How television broadcasting became widespread Experiments using electron beams to transmit and receive images over specific distances began in various countries in the early 1920s. XX century. As a result, in 1933, an American engineer of Russian origin, Vladimir Zvorykin, managed to invent a cathode tube, which is still the main part of most televisions.

At the end of 1936, the first electronic television set suitable for practical use was developed at the American research laboratory RCA, headed by Zvorykin. Later, in 1939, RCA introduced the first television designed specifically for mass production. This model was named RCS TT-5. It was a massive wooden box equipped with a 5-inch screen. Radio tubes were later replaced by semiconductors.

Today the quality of broadcasting has increased significantly and has become digital. The TVs themselves have ceased to be perceived as "boxes", for flat LCD and plasma models have appeared. The dimensions of the screen are no longer measured by a couple of tens of centimeters. Television has become the norm. By the beginning of the XXI century, the methods and principles of television broadcasting have changed significantly. Cable and satellite television emerged.

Invention

tV.

Prepared by:

Pupil 4 "A" class

Dedyaeva Christina

Since ancient times, humanity has dreamed of transmitting images over a distance. We have all heard fairy tales and legends about magic mirrors, plates with apples and the like. But more than one millennium passed before this dream came true.

The first television sets suitable for mass production appeared in the late 1930s. However, this was preceded by several decades of persistent research and many brilliant discoveries.

How it all started.

photoeffect

The era of television began after the discovery of the phenomenon of the photoelectric effect. First of all, the internal photoelectric effect was used, the essence of which was that some semiconductors, when illuminated, significantly changed their electrical resistance.

How it all started.

The first to notice this interesting ability of semiconductors was the Englishman Smith. In 1873 he reported on his experiments with crystalline selenium. In these experiments, selenium strips were decomposed into sealed glass tubes with platinum leads. The tubes were placed in a light-tight box with a lid. In the dark, the resistance of the selenium strips was quite high and remained very stable, but as soon as the lid of the box was pulled back, the conductivity increased by 15-100%.

In parallel, the development of televisions took place on the territory of the Soviet Union. The first experimental TV broadcast took place on April 29, 1931. From October 1 of the same year, television broadcasts became regular. Since no one had TVs yet, collective screenings were held in specially designated places. Many Soviet radio amateurs begin to assemble mechanical TV models with their own hands. In 1932, when developing the plan for the second five-year plan, much attention was paid to television. On November 15, 1934, a television broadcast with sound took place for the first time. For quite a long time there was only one channel - the First. During the Great Patriotic War, the broadcast was interrupted, and was restored only after its end. And in 1960 the Second Channel appeared.

Color television.

The first commercial color TV set was created in 1954 by the same RCA. This model was equipped with a 15 inch screen. Somewhat later, models with diagonals of 19 and 21 inches were developed. Such systems cost more than a thousand US dollars, and therefore were not available to everyone. However, if desired, there was an opportunity to purchase this equipment on credit. Due to the difficulties with the widespread organization of color television broadcasting, color TV models could not quickly replace black and white, and for a long time both types were produced in parallel. Uniform standards (PAL and SECAM) appeared and began to be implemented in 1967.

Development of television.

The rapid development of television in the second half of the 20th century has led to the fact that several generations have already grown up who cannot imagine life without television. Broadcast quality has increased significantly and has become digital. The TVs themselves have ceased to be perceived as "boxes", for flat LCD and plasma models have appeared. The dimensions of the screen are no longer measured by a couple of tens of centimeters. Television has become the norm.

thanks for

attention!

Prepared by:

Pupil 4 "A" class

Dedyaeva Christina

Internet sources

Images:

http://t4k.com.ua/products_pictures/55614.jpg

http : //www.ferra.ru/images/186/186435.jpg

http://mognovse.ru/mogno/883/882619/882619_html_m16bc57a3.jpg

http://profspilka.net.ua/wp-content/uploads/2015/12/ telly . jpg

https://im3-tub-ru.yandex.net/i?id\u003de5740e586b101d3ca2bc51a4e6ef3aff&n\u003d33&h\u003d190&w\u003d152

http: // pandaland.kz/assets/user_images/Untitled9.jpg

Information: http://pro-business.kz/istorija-izobretenija/televidenie.html

Ekaterina_Pashkova