Television is perhaps one of the most remarkable inventions of XX century and on a par with cars, airplanes, computers, nuclear reactor deserves the right to the epithet "the greatest", "Home", "wonderful" and "incredible." It has penetrated so deeply today into all spheres of our life, so closely connected with the life of every human being that is impossible to imagine any modern technology or modern civilization without the TV screen.
As with any complex technical creation, television appeared and evolved into a perfect system through the efforts of many, many inventors. In short chapter, of course, it is difficult to tell about all who in one way or another, put your hands and mind to the creation of television technology. Therefore, we will focus only on the most important and significant moments of the history of its occurrence.
An early forerunner of television should be considered copying telegraph Ben Alexander, for which he received a patent in 1843. The basis of the sending and receiving devices are formed wax-metal plates are arranged in a special way. For their manufacture take Ben insulated wire, cut it into pieces with a length of 2, 5 cm and tightly stuffed their rectangular frame so that the wire segments are parallel to each other, and their end faces arranged in two planes. He then filled the frame with liquid wax, cool it and polished on both sides to obtain a smooth dielectric surfaces with metallic highlights.
Ben device was suitable for the transmission of images from a metal plate or a metal typographic letters. If a metal plate or a typographic font pressed to one side of the plate metallosurguchnoy transmitting apparatus, a portion of the wires provided electrically shorted with each other and getting contact with the circuit portion supplied to the font and to a current source. This contact and passed on the same ends of the wires from the opposite side of the plate. Simultaneously, similar to the plate receiving apparatus applied wet paper sheet, prepreg potassium salts and sodium, which was able to change its color under the influence of an electric current.
Action apparatus consisted in the fact that at the same time on the transmitting and receiving stations resulted in the movement of a pendulum with fixed pin feathers on them, which slipped on the polished surfaces of the two plates (on the sending and receiving end). Now consider what happened in the telegraph lines at different positions of the contact stylus.
When the pen is slid on the dielectric of the wax plates and metal blotches, who had no contact with the cliche projections or letters font, then the circuit has remained open, and the battery current in the line did not. Touching the pin feather end of the wire connected to the print instantly closes the circuit and the current going through the connection to the receiving device, causing coloring paper section. To make the next swing, a pendulum attracted by electromagnets and briefly stopped. During this time metallosurguchnye plate using clockwork fell on a small, but the same distance down, so that at the next swing of the pendulum contact pen moved along the ends of the wires of the next row. Thus, the relief image, pressed against the plate of the transmitting device, point by point, line by line was converted into chips that arrived at collection point for the telegraph link. Here, thanks to the action of the electrochemical current image is developed on a wet impregnated paper pressed against the plate receiving device.
This ingenious invention has already contained the three essential attributes of television systems: 1) expansion of the whole of the original into separate elements (dots), which are transmitted at a time in sequence; 2) progressive scan image; 3) synchronous movement switching devices at the transmitting and receiving stations. Because of its complexity and high cost of copying telegraph received no practical application, but in its design problem of electricity transmission image was first solved for a long distance.
A similar device Bekuela, created in 1848, had more than a simple device. Special paint, do not conduct electricity, wrote the text or draw pictures on the metal foil. Then this snug foil cylinder is rotated by a clockwork. Connected to a wire with the same slider receiving apparatus along the cylinder moving a single slide contact. When the cylinder is rotated at the departure station slider touch both open and insulated foil surface. Depending on this present or absent electric current in the circuit, which react chemically treated paper, laid on the cylinder at the receiver.
A new era in the history of television began after the discovery of the photoelectric effect. First of all was the use of the internal photoelectric effect, the essence of which was that some of the semiconductors in their coverage significantly change their electrical resistance. First this interesting ability Semiconductor said the Englishman Smith. In 1873, he reported on the experiments made by him with the crystalline selenium (open in 1817 by the Swedish chemist Berzelius). In these experiments, the strips were laid selenium in glass tubes sealed with platinum inputs. The tubes were placed in a light tight box with a lid. In the darkness, the resistance of selenium strips was quite high, and remained very stable, but as soon as the box cover receded, the conductivity increased by 15-100%. A simple movement of the hand over the tubes of selenium increased the resistance by 15-20%. (The explanation of this interesting phenomenon was found much later, when the quantum theory of light was created. The ability of a substance to conduct or not conduct current, as we know, it depends on whether there is it free charged particles. In the normal state in selenium crystal no such charged particles. However, upon illumination of light photons knock part selenium atoms electrons. These electrons move freely between the semiconductor crystal lattice sites just as electrons in the metal. Thus, the semiconductor properties of the conductor and acquires its resistance is significantly reduced.)
Soon Smith's discovery was widely used in television systems. It is known that every object becomes visible only when it is illuminated, or if a source of light. Light or dark areas of the observed object and its image are different from each other with different intensity of the reflected light or emitted by them. Television just based on the fact that each item (if it does not take into account color) can be regarded as a combination of a large number of more or less light and dark pixels. From each of these points to the viewer is the luminous flux of varying intensity - from bright points stronger, the dark - is weak. Consequently, if it were possible to create such a device that the transmitting station has converted light image signals incident thereon into corresponding electrical impulses of varying strength, and at the receiver again turns these pulses into light signals of different intensity, the problem of image transfer to the distance would be in generally permitted. After opening the internal photoelectric effect it became apparent that such a device can process the plate can serve as selenium.
In 1878, a professor of physics Portuguese Adriano de Paiva in a scientific journal introduced the idea of a new device for transmitting images over the wire. The transmitting device de Paiva is a camera obscura, on the back of which a large selenium plate was installed. Various portions of the plate have been differently change their resistance depending on the lighting. However, de Paiva admitted he did not know how to produce the opposite effect - to make the screen glow in the receiving station. In 1880, Paiva has released a brochure "Electric telescope" - the first in the history of the book, specifically devoted to television. It was given to the further development of the ideas set out in the two years before that. Thus, the transmitted image projected on the optical path of the plurality of plate elements of selenium. The current from the battery is supplied to the metal contact, which quickly moved over the plate. If a segment was lit brightly, his resistance was low, and the current with him turned out to be stronger than the one that was shot with poor lighting segment. As a result, transmitted by wire electrical signals of varying strength. At the receiver, the movement of the contact simultaneously repeated light bulb, move behind frosted glass, which was burning brightly, then dim depending on the current pulse power (that is, on the light of selenium each segment plate). According to de Paiva thought if we could get a fairly rapid movement of the contact and the bulb, the viewer, who was staring at the ground glass, was to create a visual representation of the projected object. How to achieve this, de Paiva did not know. However, for its time it was a very interesting idea.
In 1881, French lawyer Konstantin Senlek in the brochure "telectroscope" described the project a television device consisting of two panels - the transmitting and receiving - and the same number of discharge lamps. The image projected on the matrix of the plurality of transmission elements of selenium, resulting in each of the cells, depending on the lighting, the current shot certain value. In the transmitting and receiving stations are interconnected electric wire mechanical switches, acting perfectly in sync. The transmission switch at high speed shut himself consistently to all cells of the matrix (as if obegaya them line by line), and passed on to each of them talk to the receiving switch. As a result, on the receiving panel flashing light bulbs, each burning though more or less intense, depending on the magnitude of the transmitted current. Senlek built a working model of his telectroscope, but was unable to pass on it is nothing other than a few points of light.
The weak point of the first television systems remained a mechanical switch. In fact, to an observer on the retina of the eye to create an image transmitted his image on the screen of the receiving station for one second should be replaced by a dozen snapshots. That is, the image scan (time it takes to signal the removal of all cells transmitting selenium plate) should take about 0, 1 second. Scan using the moving contact, invented another Ben, for this purpose obviously was not suitable.
It has been proposed several ways to resolve this difficulty. Finally, in 1884, a young German student Paul Nipkow found a classical solution of the problem of scanning transmitted pictures. The main parts of the device Nipkow was opaque disc with tiny holes around the outer edge. The distances between the holes are the same, but each following was shifted to the center of the disc on the value of the hole diameter.
Image transfer was carried out as follows. The lens is projected to drive reduced real image of the object. On the other side of the disc was placed selenium plate. ROM drive with an electric motor in a very rapid rotation. In this case, every time the light to the element through one got some opening moves in an arcuate line. First, between the image and the photosensitive plate was held an upper opening through which a photocell successively projected image, only the upper edge. When the hole was spent for the frame image, with the other edge of the frame progressed both located slightly below and to project onto the next photocell strip (or, later, began to say, - "line") of the image. Thus, in one revolution of the disk before the photocell alternately passed all parts of the image. (This process is called "progressive scan image", is one of the central TV system. "Nipkow disk" was the first simple device that allowed to carry out such a scan. During the next fifty years, he was an integral part of many TV devices.) Further signals from each photocell cell sequentially transmitted over the wire to the receiving station. Here, the current supplied to the neon lamp, which, respectively, it was burning brightly, then weaker, depending on the strength of the transmitted power. Between the observer and the lamp was placed a perforated disk, as well as to the transmitting station, rotating him in strict synchrony. At any time, the viewer can watch the glowing lines, brightness elements of which was proportional to the brightness of the same elements on the transmitter disk. In general, the device has already been Nipkow all major components of so-called "mechanical" television.
First, the inventors of television supposed to send electrical signals through wires, but only began to develop a radio, was the thought that these signals can be transmitted by means of electromagnetic waves. For the first time I put forward the idea of 15-year-old schoolboy Poland Mieczyslaw Wolfke, which in 1898 filed a patent application on the first television device without wires. Wolfke transmitting apparatus was the same as that of Nipkow, only signals transmitted from the photocell to the primary coil is a transformer, the secondary winding of which snaps to the dipole antenna, radiating electromagnetic waves. At the receiver, the current supplied to the neon lamp and the projection of the image is the same as that of Nipkow.
Despite the successful resolution of scanning issues or Nipkow nor his followers failed to transfer images. Simple solar cells, converting the brightness of the transmitted point to an electrical signal, giving a very weak current pulses, which was lost in a more or less extended link. Although individual inventors were able to build active devices and transmitted through them elementary image, had at their disposal the technical means is not allowed to make experiments outside the laboratory. The main obstacle to the further development of television was the lack of an essential element of communication - signals the amplifier. Only after the invention of vacuum tubes that obstacle has been overcome.
The development of television also contributed to new discoveries in the field of the photoelectric effect. In 1888, Russian physicist Ulyanina found an interesting phenomenon - at the metal-selenium illuminated by the light source begins to produce an electric current. Ulyanina hastened to use this feature and made the first selenium solar cell with a thin gold film, is produced by the light low current. (This effect is now widely used in the art, for example, in solar batteries.) Recall that previously was known only one manifestation selenium photosensitive properties - resistance change. Therefore, selenium photocell circuit had to be sure to include the power supply - external battery. Now the need for it anymore.
The first practical television systems have been created only in the XX century. In 1923 Charles Jenkins carried out a transfer of a still image on the radio from Washington to Philadelphia and Boston, and in 1925 he managed to convey the image of moving figures. To scan Jenkins used the disk Nipkow, and to enhance the video signal - power electron tubes. At the receiver, used neon lamp, which the viewer looked through the other holes Nipkow disk and seen in terms of different brightness, were located in exactly the same manner as in the transmitted image. For this purpose the receiving disc rotates at the same speed, and that transmits, making 12 5 revolutions per second (in other words, the viewer in one second was replaced by 12, frame 5 - sufficient speed in order to transmit motion). Later, the speed was increased to 25 frames per second. Successful results were also achieved in England. In 1928, Scotsman John Baird founded Europe's first joint-stock company and the television began experimental transmission via radio, based in London. His own company has adjusted release of the first mechanical television. Images of them are deployed to 30 lines.
The general public first reacted with enthusiasm to the new invention. Spectators were lenient even to that image in their TVs often been dark, fuzzy and vague. However, over the years, the enthusiasm cooled. It turned out that to get a good, clear picture in a mechanical television impossible. (It is estimated that this Nipkow disk should scan at 600 lines from the hole diameter is about 0 to 1 mm. In this case the disc diameter reaches 28 m. When rotating at a desired rate it inevitably will disperse by centrifugal force.) Although many large cities (including Moscow and Leningrad) had its own television studio, and tens of thousands of people were at home TVs, widespread mechanical television did not work and eventually gave way to the championship throughout the electronic television, which now will be discussed.
electronic television era began with the invention of the cathode ray tube. The prototype e-tube discharge lamp was invented in 1856 by German glassmaker Geisler, who learned fused into the glass flask platinum electrodes and produced the first gas-filled tube. Now discharge lamps distributed throughout, and their arrangement is well known: on both sides of a glass tube filled with some gas, two electrodes are placed. When these electrodes are energized by a high current source, an electric field between them. In this field, the gas molecules are ionized (losing their electrons) and are converted into charged particles. As a result of going through the tube electric discharge under the influence of which the gas begins to glow brightly.
This phenomenon is directly interested many scientists. These include Plucker and professor at Bonn, for which Geisler He produced specially sealed tubes with different gas mixtures. In 1858, Plucker noted that when an electric current glass near the cathode glow somehow in a special way, not like in other parts of the lamp. After studying this effect, Plucker concluded that near the cathode when an electric discharge occurs some radiation, which he called the "cathode". In 1869, German physicist Hittorf discovered that cathode rays can deviate by a magnetic field. In 1879, the English physicist William Crookes conducted a fundamental study of cathode rays, and came to the conclusion that with the cathode surface when heated emits a stream of some particles. (In 1897, the English physicist Thomson proved that cathode rays are a stream of charged particles -. Electrons) for his experiments Crookes created a special tube, which was the first in the history of the cathode-ray tube.
Incidentally Crookes discovered that certain substances (they are called phosphors) begin to glow when bombarded by cathode rays. In 1894, Lenard found that the phosphors glow, the stronger the greater the cathode current. In 1895, the Strasbourg University Professor Karl Braun on the basis of Crookes tubes created cathode (e) an oscilloscope designed for the study of different electrical currents.
In Brown cathode tube was covered with the diaphragm - screen with a small opening, whereby the cathode emitted beam is not wide, as in the experiments of Crookes and narrow beam. Outside the glass flask was placed a coil on which current is supplied investigated. This current passes through the coil, creating a magnetic field around the variable that deviates cathode ray in the vertical plane. Screen served a glass plate covered by the phosphor of the cathode. The beam passing through the diaphragm and create a small bright spot on the screen. Under the influence of a magnetic field deflecting the beam began to fluctuate and are drawn on the screen vertical line that marked the maximum and minimum values of the test current. With the help of mirrors, this luminous line projected onto the external screen. Somewhat later, in 1902, Russian scientist Peter Brown perfected tube, proposing to use a second coil for an electron beam deflection in a horizontal plane. Now, feeding the appropriate signals, it was possible to make the beam obegat full screen. In 1903, German physicist Venelt made another improvement - he introduced into the tube cylindrical electrode, negatively charged. By varying the strength of the charge on this electrode, it was possible to amplify or attenuate the electron flow from the cathode, making the point on the screen is more bright, then dim. In 1907, Leonid Mandelstam suggested to control beam in the tube Brown used two systems of deflection plates to which was applied a sawtooth voltage. This electron beam is drawn on the screen became a so-called raster - glowing lines that were located one above the other on the top edge of the screen to the bottom. It happened as follows. On the path of the electron beam in the tube placed two vertically oriented plates, which, as already mentioned, was applied AC voltage sawtooth waveform generated by a special generator. When this voltage is equal to 0, the electron beam is held on the screen for a starting position. Then, after the positive plate is started at a certain rate to charge, electrons are deflected to her and the end of the beam was moving across the screen. This continued movement as long as the voltage is not positive plate becomes maximum. After that, the voltage decreased rapidly, and the electron beam rapidly back to its original position. Then everything was repeated again. At the same time the beam to oscillate in a vertical plane. To reject a vertically designed a second pair of plates. It is easy to see that if the frequency of the sawtooth voltage applied to the vertical plates, was 10 times greater than that which was applied to the horizontal, for the time corresponding to one frame, managed to form a beam of 10 lines. Instead of the alternating electric field can be used alternating magnetic generated by the two coils. All these discoveries and inventions laid the fundamentals of electronic television.
The first who proposed to use a cathode ray tube for a television program, was a Russian physicist Boris Rosing. In 1907 he received a patent for a method of electrical transmission image at a distance.
For progressive scan image Rosing used two mirror drums, is a multifaceted prism with flat mirrors. Each mirror was tilted slightly to the prism axis and the angle is uniformly increased from mirror to mirror. When rotating drums light rays coming from the different elements of the transmitted image, reflected consistently mirror faces and alternately (line by line) fell on the photocell. The current transmitted to the photocell on the capacitor plates. Depending on the magnitude of the supplied current passed between them a larger or smaller number of electrons, allowing to change the brightness of illumination of the corresponding points of the luminescent screen. (The electric field inside the capacitor when the signal voltage change deflects the beam vertically, so that changes the number of electrons reaching the screen through a hole in the diaphragm.) Thus, the tube replaced just two node previous mechanical systems scanners (eg Nipkow disc) and a source light (for example, gas-discharge lamp). Two mutually perpendicular coils controls the movement of the beam so that it is drawn bitmap (begins to move from the top left corner of the screen and ends in the right corner, then quickly returned to the left side, fell down a bit and did scan the second line). The movement of the beam and the rotation of the mirror drum was strictly synchronized with each other, so that the passage of each projected verge of passing the photocell corresponds to the passage of a line projecting beam. On passage of the entire screen expend beam about 0, 1 second. This ray image perceived by the eye as a whole image.
After a long and persistent experiences with his imperfect equipment Rosing managed to get the first image - a brightly lit lattice - on the screen of the receiver. This image is composed of four lanes. When closed one of the lattice openings, the corresponding bar on the screen disappears. Television can transmit an image of simple geometric shapes, as well as the movement of the hand. Rosing invention of messages were published in technical journals of the USA, Japan and Germany, and had a major impact on the further development of television. Although Rosing belongs to thank the founder of electronic television, his television system has not yet fully electronic - recording and transmission of images produced by a mechanical device - SLR drums. E in his system was only receiving tube, in which the device is already possible to see the many features of the black-and-white TV. The next step was to be the creation of a cathode-ray tube transmission, the effect of which is based on the outer photoelectric effect.
External photoelectric effect was discovered in 1887 by Heinrich Hertz and deeply studied in the next year, the Russian physicist Alexander Stoletov. The essence of this phenomenon lies in the fact that the light comes knocking electrons from the surface of a charged plate. Embossed electrons form a cloud that is attracted to the positive electrode to form an electric current in a vacuum or gas discharged. This principle is based photocell work, created in 1906 by the German scientist Dember. The cathode and anode are placed in a glass flask, of which the exhausted air. K - cathode coated with a photosensitive material (preferably cesium); A - anode which is a metal mesh and does not interfere with light passing to the anode; S - light source; E - battery. Light incident on the photocathode photocell, frees electrons from it, that rush to the positively charged anode. The reduction or increase in the photocathode lighting respectively increases or decreases the current in its chain.
In 1911, the English engineer Alan Swinton proposed project television device in which a cathode ray tube used not only as a receiver, but also as a transmitter. At the heart of the camera tube Swinton - Crookes tube, which was applied to the cathode of a negative voltage of 100,000 volts with respect to the anode. The narrow beam of electrons passing through the aperture in the anode, and C incident on the screen I, describing it using raster deflection coils E. The screen consisted of a tiny, isolated from each other rubidium metal cubes. On the opposite side through the mesh L and sodium vapor chamber from the screen I projected image. The light from each point falling on separate rubidium screen cube, which operated as an independent cell, and knocked him to the surface electrons. In accordance with the laws of photoemission of the electrons of these was the more than intensity is the effect of light. Until then, until the cube is not applied voltage, electrons are knocked out near the screen. But when an electron beam swept one after another, all the blocks, you get on some of them, who receive a negative charge. Then the electrons ejected from the surface light cubic grid rushed to L, which is consequently at each time point was on her charge corresponding to some point on the screen. This charge was removed from the grid and then transmitted as a video signal to a receiving tube, which device is based on the same principles as that of the Rosing. Electron beam tube receiving beam is synchronized with the camera tube, and its intensity at each point is directly dependent on the strength of the video signal is sent. Practical Action TV installation Swinton did not create, but in its design we already see those basic elements that were then in the design of all subsequent generations of transmitting tubes: two-way mosaic of many individual solar cells with an external photoelectric effect, in the form of a collector grid L and deflection coils E.
The next step in the development of television was made only in the 20s. In 1923, Vladimir Zworykin (a student Zworykin was one of the students Rosing and actively assisted him in creating the first TV, and in 1917 he emigrated to the US, where he worked until his death) has patented a fully electronic television system with the transmission and reception of electron ray tubes.
The transmitting tube Zworykin applied three-layer double-sided target. The tube is composed of the signal plate 4 - the aluminum thin film (transparent to electrons) is coated on one side of an insulator 3 made of aluminum oxide, which has been deposited on the photosensitive layer 2 having an external photoeffect. Next to this layer was established grid 1. On the aluminum foil was applied to a positive (with respect to the grid) voltage. The image was projected on this layer through a grid 1. On the other side of the aluminum foil 5 of the electron beam of the electron gun 6, creating a pattern. Signal RH shot load in the grid circuit. Mosaic transmitting tube comprises a plurality of individual solar cells. This tube also did not become a working model, but in 1929 Zworykin developed a high-vacuum receiving cathode-ray tube, which he called a kinescope, which is later used in the first TVs. Thus, the receiving CRT was created in the early 30s.
On transmitting things were more complicated tubes. All inventors proposed by the end of the 20s electronic tube has one significant drawback - they have a very low sensitivity. The video, taken from the them, was so weak that he could not provide not only a good, but any satisfactory image. Low sensitivity is fairly explained by the inefficient use of light. Indeed, assume that the photosensitive mosaic plate 10 is divided into thousands of cells, and the electron beam runs them all at 0, 1, p. This means that the transmitted image light negative pressure acting on each single cell only during 1/100000 second. If we could harness the energy of the light flux, it is useless to disappear for the rest 99999/100000 seconds, the sensitivity of the television system would have to increase significantly.
One of the first to attempt to solve this problem already known American engineer Charles Jenkins. In 1928, he proposed a device for storing a charge in a television tube. The essence of the idea Jenkins was the fact that each light-sensitive photocell panels connected a capacitor C. The light falling on the solar cell, and the resulting current charges the capacitor during the frame transmission time. Then use the switch capacitor alternately discharged through the RH strain, from which the signal is removed, that is, as the video Jenkins suggested to use a discharge current.
The idea Jenkins was very fruitful, but it needed to be further developed. First of all have to think about where and how to place dozens or even hundreds of thousands of small capacitors (after all, every single screen cell had to have a capacitor), then required to create a switch that would be at the desired speed and synchronicity could produce a discharge of all these capacitors. No mechanical device can not cope with this task. Therefore, the role of the switch began charging the same electron beam. In the next five years in different countries, several options for the transmission pipe, using the charge accumulation principle it was suggested, however, all of these projects have not been implemented. Successfully overcome numerous obstacles fortunate enough Vladimir Zworykin. In 1933, at the Congress of Society of Radio Engineers in Chicago, he announced that his ten-year efforts to build a functioning television tube complete success.
This work began in Zworykin "Westinghouse" company lab, and finished in the "On Air America", which was at his disposal a well-equipped laboratory and a large group of experienced engineers. After many experiments with the help of a chemist Zworykin Iziga found a very simple method of making a photosensitive mosaic target with the storage capacitor. It happened as follows. Braley mica 10 x 10 cm plate on one of its sides a thin layer of silver. The plate was placed in a furnace. A thin silver layer by heating acquires the ability to curl up into pellets. Thus on a mica plate was formed several millions of isolated granules. Then, on the silver layer was deposited cesium, possessed, like selenium, increased sensitivity to light. On the opposite side of the mica plate was coated with a continuous metallic layer. This layer would serve as a second capacitor plate relative to the granules cesium photosensitive silver layer. As a result, each of the millions of tiny solar cells served at the same time and a miniature condenser. This tube Zworykin gave the name of Ike.
iconoscope works as follows. Glass spherical balloon was equipped with a cigar-shaped cylindrical appendage, which was placed in an electron gun. In the bowl was a target, set obliquely to the axis of the ridge. This target, as already mentioned, consisted of mica plate, one side of which a metal layer is applied to the signal, and the other - light-sensitive mosaic, consisting of a plurality of isolated photovoltaic cells (5). Part of the spherical surface of the glass bulb tube was made flat, parallel to the target. Through her mosaic projected image, so that the axis of the lens is perpendicular to the plane of the target (this excludes any distortion) Near the mosaic in front of the light-sensitive layer was placed mesh (1), which was applied a positive relative to the anode (3) charge (anode grounded and a large negative potential) was created on the hot cathode (4). The electron beam (2) passes through the mesh and create a mosaic raster. Signal is taken from the signal plate (6) and fed to the resistance RH, and then to the amplifier tubes (7). The electron beam, running along the photomosaic, consecutively discharged all of its sites. As a result, we formed the electrical impulses (video signals) proportional to the illumination areas of the mosaic. These pulses are amplified and fed to a radio transmitter. In the future, Ike has been greatly improved. The ball was replaced with a cylinder appendage to the electron gun. Instead of nets, which distort the signal applied steel collector (8) is a metal ring. On the inner surface of the cylinder going photoelectrons emitted mosaics.