Baird's above-mentioned patent proposes a method and system for transmitting images, portraits and scenes, in which each area of the scene is continuously projected onto a photosensitive element, and a receiver uses a current change caused by the photosensitive element to light up a series of small lamps arranged in a screen, and the varying illuminance of these small lamps forms a reproduced original picture on the screen. The invention will be further explained with reference to the drawings and embodiments: the scene or object A to be transmitted is focused on the rotating disk D through the lens B to form an image C, and a series of holes arranged in a spiral line are penetrated on the disk D. The imaging C can be 1 inch×1inch, and the diameter of the holes on the disk can be118 inch. These holes are circumferentially distributed about 65438 0 inches. The second hole is closer to the center than 118 inch (or 1/32 inch) and the third hole is closer to the center than the second hole118 inch (or 65438 inch). So that when the disc D rotates, each part of the image to be transmitted successively passes through the hole of118 inch (or the hole of 1/32 inch). There is a photosensitive element E on the back of the optical disc. Different lights shine on the photosensitive element through the perforation M, so that the current flowing through the photosensitive element from the battery F changes, and the changed current is amplified by the thermionic vacuum tube, and then transmitted to the receiver through wires or elements. The receiver is equipped with an arm G that rotates completely synchronously with the disc D of the transmitter. The end of the arm is provided with a brush, which is communicated with a series of contacts H, and each contact is connected with a small lamp. These lamps are arranged in rows and columns to form a screen K, and each hole sweeps a strip of the picture, and the strip is reproduced on the receiving screen by a row of lamps, so that each hole has its corresponding row of lamps, and many lamps can be used. The more lights, the better the reproducibility of the picture. If the corresponding instantaneous hole faces the bright part of the picture, the light will be very bright; If the hole is facing the black part of the picture at that moment, the light will be dim; Light with different brightness on the screen reproduces the picture, thus forming an image.
Baird was born in 1888. He studied at Hulack Field College, Royal Institute of Technology and Glasgow Primary School, but dropped out of school because of the outbreak of World War I. He was an unsuccessful businessman. When he started his research work, he was poor and had no funds. He had to use tea boxes, biscuit boxes, wires, wax and other waste materials to make his own experimental device. Even the rotating disk is made of cardboard, with 30 lines from top to bottom and 65,438+00 transmissions per second.
1924, he successfully launched the Maltese Cross within a few meters. 10.2, he finally succeeded in making the face of the young handyman Willian Tynton appear on TV. He signed a contract with a department store to get paid for TV transmission performance and constantly improve the system.
From 65438 to 0928, Baird began to broadcast its TV system officially, and began to study and experiment with color TV.
1929, the British Broadcasting Corporation (BBC) signed a license contract with Baird to use his invention to broadcast TV on the basis of experiments.
1936, the BBC realized the scheduled TV broadcast by radio for the first time in the world. However, the limitations of Baird's TV adopting mechanical technology route have also emerged. Although he has made little efforts, the quality of the transmitted picture has always been problematic. The scanning accuracy is limited by the rotation speed, the image definition is not enough, and the flicker of the picture makes the audience a headache. Very active in this field at that time. When Baird was engaged in the research of TV system according to the principle of mechanical scanning, American inventors were studying electronic scanning, trying to adopt another technical route-electronic TV system. Russian-American engineer Vladimir K. Volgin J1923 65438+applied on February 29th, and the published patent US2 14 1059 was approved on February 20th 1938, and the technology of kinescope and camera tube was invented. It laid the foundation for the electronic TV system. Although the electronic TV system was not perfect at first, the effect was not as good as mechanical. However, with the efforts of Volgin, American Wireless Company and British EMI Company, the technology has made rapid progress, such as scanning line 1929 is 48 lines, and 1935 reaches 343 lines.
Although Volgin's picture tube makes TV practical, it can't make TV transmission easy or perfect. The "photoelectric camera tube"-which is often mentioned by TV personnel-can produce clear images, but it is not very sensitive to light. In the bright sunshine, everything is normal, but in the studio, only a very small amount of light is needed-more than the film industry needs. When the heat exceeds 100 degrees Fahrenheit, actors and actresses need makeup (including thick eye shadow box lip gloss) to offset the dazzling light from the old arc lamp. Volgin and his team should remedy this!
At the end of 1936 and the beginning of 1937, two systems, EMI's electronic TV system and Baird's mechanical TV system, were set up in Alexandra Palace in the north of London, England, and used in turn every other week, and the two systems were compared. Electronic variety show technology is first-class. Three months later, the BBC told Baird that he would shut down his system. Electronic TV system has become the mainstream system of TV. Baird died in Beukes Hill, Sussex, England on 1946.