According to Korn, who is often credited as the first inventor of the television tube, the apparatus utilized “Tesla currents.” In 1920, Tesla explained in an Electrical Review article entitled “The Art and Practice of Telephotography,” that Korn’s tube, which was based on a tube displayed in the early 1890’s by Tesla, “is excited by a high-frequency current supplied from a Tesla transformer and may be flashed up many thousand times per second” thereby attaining the moving television image. That’s precisely how the TV tube works. Filo Farnsworth, often credited as the inventor of the TV tube was 14 years old in 1920.
The New Wizard of the West - Pearson's Magazine - May 1899:
"Now, as sound waves of the human voice are transmitted miles and miles by the present telephone after their impression is made on the telephone transmitter," says Mr. Tesla, " just so my experiments have demonstrated that the light waves of the human body can be transmitted by a different sort of telephone miles and miles away. All we need is the invention of a new transmitter. As the impressions of light waves are so many times more delicate than the impressions of sound waves, it follows that to transmit the impression of the human face, for instance, we require a transmitter many times more delicate. Now, selenium being an extremely sensitive substance, I have utilised this material in the construction of the transmitter which I have just described, and I have found it to be perfectly satisfactory."
The Art and Practice of Telephotography - by Nikola Tesla - Electrical Review - December 11, 1920:
Dr, Korn was the most successful as well as prolific in the suggestion of improvements, his photographic method of recording carried out in 1903 being the most significant. The general idea of photographic recording had been already advanced by George Little, and a few years later, Dillon took out a patent involving the use of sensitized paper and a mirror retiecting a beam of light on the same. But it is obvious that at that time it would have been hardly practicable to use this suggestion, as photography was not sufiiciently advanced. In illustration of this it may be mentioned that in I892 the attention of the scientific world was directed to a wonderfully sensitive receiver, consisting of an electron stream maintained in a delicately balanced condition in a vacuum bulb, by means of which it was proposed to use pho- tography in the transmission of telegraphic and telephonic messages through the Atlantic cables, and later also by wireless. This proposal was met by unsurmountable objections to the pho- tographic method. Indeed, the Belin process has been rendered possible largely through the great improvements in the sensitive films which have been evolved in response to the urgent demands of the motion picture and also under the stimulus of the recent war.
SELENIUM CELL AND VACUUM TUBE USED TO TRANSMIT AND RECEIVE.
In the apparatus invented by Dr. Korn a selenium cell is used at the transmitter to vary the intensity of the sending current, and at the receiving station he employs a vacuum tube of high intensity which throws its light through a fine slot on a sensitive plate. The tube is excited by highfrequency currents supplied from a Tesla transformer and may be flashed up many thousand times per second. The motion of the receiver element is effected either by a wire galvanometer, oscillograph or telephone diaphragm. The Korn's system has been used for some years past with success in Germany and other countries. In fact it has been operated for some time even by wireless. Patents on this mode of transmission have been granted in 1898 and 1899 to Küster and G. Williams, but the arrangements involved the employment of Herz waves and were impracticable. Later Frederick Braun, Pansa and Knudsen secured patents which, however, are equally defective. Success in this direction has been achieved so far only by Korn, Berjonneau and T. Baker. Invariably the inventors employ a wire galvanometer which is suitable for great speed. Telautographic transmission by similar means through wires as well as wireless is now common and is effected by employing a transmitter of two components, the original idea of which is due to an Englishman, Jones, who made that suggestion as early as 1855.
PRESENT DEVELOPMENTS INVOLVE OLD PRINCILPES
To this short story of picture transmission, Belin has contributed the latest chapter. The process he has finally adopted after many years of a presistent effort involves the use of two cilinders rotating in sinchronism - one for transmittion and the other for reproducing. The former is of copper and is prepared for opperation by having its surface coated with a thin shellac solu- tion, wrapping a carbon print of the photograph about it with its face to the cylinder and im- mersing the whole in hot water, this causing the gelatine to adhere to the cylinder surface in pro- portion to the degree of blackness so that a like- ness of the print in bas-relief is obtained. On this cylinder bears the stylus of a microphone diaphragm which is slowly moved forward by the revolution of the cylinder as in a phonograph.
In this manner the pressure ot the carbon con- tacts is varied in conformity with the changes of the surface, and the microphone currents pass over the transmitting wire to the receiving station where ,theycause corresponding dellections of a mirror forming part of a highly sensitive dead- beat oscillograph. A strong beam of light re- flected from the mirror traverses a screen gradu- ated from 'full transparency to opacity and is led through a microscopic opening to the sensi- tive tilm wrapped around the receiving cylinder. Special provisions are made to keep the cylinders exactly in step as this is indispensable to good performance. The film is, of course, protected against the external light, and when the operation is completed it is developed as_usual so that either a positive or negative print is obtained according to the position of the screen. There is nothing in his apparatus which is funda- mentally novel; in fact, every feature of the same has been disclosed in the prior art. Even the graduated scrcwcn, which is one of the most essential parts, has been employed before by Dr. Korn. But Mr. Belin has displayed considerable ingenuity and skill in all the details, and his re- produced photographs are most excellent. There is every reason to believe that his ettorts will be rewarded by an extensive practical application of his devices.
TELEVISION TO BE THE NEXT STEP IN PROGRESS OF TRANSMISSION
The transmission of photographs constitutes only the first step towards the immeasurably greater achievement of television. By this is meant instantaneous transmission of visual im- prcssions to any distance by wire'or wireless. It is a subject to which I have devoted more than 25 years of close study. Two of the impediments \vhich years ago seemed unsurmountable have been successfully overcome, but great difticulties are still in the,way. These are encountered in the inertia of the sensitive cells and the enormous speed required to make possible the vision oi persons, objects or scenes as in life. It is the problem of constructing a transmitter analogous to the lens and retina of the eye, providing a medium of conveyance corresponding to the optic nerve, and a receiver organized similarly to the brain. It is a gigaptic task, but I am confident that the world will witness its actual accomplishment in the near future.
1902 Prof. Dr. Arthur Korn, a German, demonstrated the first photo-electric scanning fax system. The previous methods had depended upon Bain’s contact-scanning technique. In 1902, Prof. Dr. Arthur Korn developed a photoelectric scanning system for the transmission and reproduction of photography, and in 1907, he established a commercial picture transmission system. This system eventually linked Berlin, London and Paris and became the world’s first facsimile network
1903 Prof. Dr. Arthur Korn demonstrates the first photoelectric telephotography
The first practical photoelectric facsimile system is demonstrated by Dr. Arthur Korn.It employs the light-sensitive element selenium to convert the different tones of a scanned image into a varying electric current. This enables 'halftone' illustrations to be transmitted for the first time. Commercial use of Korn's system began in Germany five years later. By 1910, Paris, London and Berlin were all linked by facsimile transmission over the telephone network.
Facsimile then made slow but steady progress through the ‘20s and ‘30s, and in 1934 the Associated Press introduced a wire photo service. Korn’s breakthrough of giving the fax machine “sight” prompted serious commercial experimentation by three American telecommunications giants: AT&T, RCA and Western Union. Korn’s success and achievement in using the fax brought new development and direction for broadcast publishing to the United States.
Prof. Dr. Arthur Korn establishes also a commercial picture transmission system which uses radio waves to transmit pictures between Paris, London and Berlin.
1906First facsimile test between Munich and Nurnberg
1907 Prof. Dr. Arthur Korn developed the first commercial fax system to transmit pictures between Paris, London and Berlin.
First facsimile test for “LÍllustration” Paris - Lyon - Paris. “Daily Mirror” London - Manchester - Paris. “ Berliner Lokal-Anzeiger” Munich - Berlin - Paris - Copenhagen - Stockholm.
1908 First facsimile test for “Politiken” Copenhagen - Berlin - Stockholm. “ Dagens Nyheter” Stockholm - Copenhagen
1909 First facsimile test for “Colliers Weekly” New York - Washington.
1911 The first amplitude modulator for fax machines is patented, permitting transmission via telephone lines.
1913 Edouard Belin's Belinograph
1922 The first transatlantic facsimile services was provided by RCA.RCA faxes photos across the Atlantic in six minutes; AT&T, RCA and Western Union develop “high-speed” fax systems.
Dr Arthur Korn's facsimile system is used to transmit, by radio, a photograph of Pope Pius XI from Rome to Maine, USA. The picture is published the same day in the New York World newspaper. - a major feat in an era when news pictures crossed the ocean by ship.
The most "sensitive device" developed by Nikola Tesla could be considered as a forerunner of the three-electrode tubes which could be used to amplify and rectify the signals. He designed different bulbs to investigate this phenomena, and it was many years before the invention of the "Audion" (or also known as triode) in 1906 by Lee de Forest. Tesla's three-electrode tubes are described in the article "Pioneer Radio Engineer Gives Views On Power" - New York Herald Tribune - September 11, 1932:
"The chief object of employing very short waves is to provide an increased number of channels required to satisfy the ever-growing demand for wireless appliances. But this is only because the transmitting and receiving apparatus, as generally employed, is ill-conceived and not well adapted for selection. The transmitter generates several systems of waves, all of which, except one, are useless. As a consequence, only an infinitesimal amount of energy reaches the receiver and dependence is placed on extreme amplification, which can be easily affected by the use of the so-called three-electrode tubes. This invention has been credited to others, but as a matter of fact, it was brought out by me in 1892, the principle being described and illustrated in my lecture before the Franklin Institute and National Electric Light Association (Experiments with Alternate Currents of High Potential and High Frequency). In my original device I put around the incandescent filament a conducting member, which I called a "sieve." This device is connected to a wire leading outside of the bulb and serves to modify the stream of particles projected from the filament according to the charge imparted to it. In this manner a new kind of detector, rectifier and amplifier was provided. Many forms of tubes on this principle were constructed by me and various interesting effects obtained by their means shown to visitors in my laboratory from 1893 to 1899, when I undertook the erection of an experimental world-system wireless plant at Colorado Springs".
On Light and Other High Frequency Phenomena - A lecture delivered before the Franklin Institute, Philadelphia, February 1893, and the National Electric Light Association, St. Louis, March, 1893
The True Wireless by Nikola Tesla - Electrical Experimenter - May 1919:
"My confidence that a signal could be easily flashed around the globe was strengthened thru the discovery of the "rotating brush," a wonderful phenomenon which I have fully described in my address before the Institution of Electrical Engineers, London, in 1892 (Experiments with Alternate Currents of High Potential and High Frequency), and which is illustrated in Fig. 9. This is undoubtedly the most delicate wireless detector known, but for a long time it was hard to produce and to maintain in the sensitive state. These difficulties do not exist now and I am looking to valuable applications of this device, particularly in connection with the high-speed photographic method, which I suggested, in wireless, as well as in wire, transmission."
Colorado Springs Notes - July 23, 1899:
"In investigating the propagation through the media, and more particularly through the ground, of the electrical disturbances produced by the experimental oscillator, as well as those caused by lightning discharge, to which work a few hours were so far devoted every day, a form of sensitive device used in some experiments in New York was adopted, as the best suitable for these purposes".
The Problem of Increasing Human Energy: With Special Reference to the Harnessing of the Sun’s Energy. by Nikola Tesla - Century Illustrated Magazine - June 1900
When I advanced this system of telegraphy, my mind was dominated by the idea of effecting communication to any distance through the earth or environing medium, the practical consummation of which I considered of transcendent importance, chiefly on account of the moral effect which it could not fail to produce universally. As the first effort to this end I proposed at that time, to employ relay-stations with tuned circuits, in the hope of making thus practicable signaling over vast distances, even with apparatus of very moderate power then at my command. I was confident, however, that with properly designed machinery signals could be transmitted to any point of the globe, no matter what the distance, without the necessity of using such intermediate stations. I gained this conviction through the discovery of a singular electrical phenomenon, which I described early in 1892, in lectures I delivered before some scientific societies abroad, and which I have called a "rotating brush." This is a bundle of light which is formed, under certain conditions, in a vacuum-bulb, and which is of a sensitiveness to magnetic and electric influences bordering, so to speak, on the supernatural. This light-bundle is rapidly rotated by the earth's magnetism as many as twenty thousand times pre second, the rotation in these parts being opposite to what it would be in the southern hemisphere, while in the region of the magnetic equator it should not rotate at all. In its most sensitive state, which is difficult to obtain, it is responsive to electric or magnetic influences to an incredible degree. The mere stiffening of the muscles of the arm and consequent slight electrical change in the body of an observer standing at some distance from it, will perceptibly affect it. When in this highly sensitive state it is capable of indicating the slightest magnetic and electric changes taking place in the earth. The observation of this wonderful phenomenon impressed me strongly that communication at any distance could be easily effected by its means, provided that apparatus could be perfected capable of producing an electric or magnetic change of state, however small, in the terrestrial globe or environing medium.
The Problem of Increasing Human Energy: With Special Reference to the Harnessing of the Sun’s Energy. by Nikola Tesla - Century Illustrated Magazine - June 1900