Technikatörténeti szemle 20. (1993)

TANULMÁNYOK - Tihanyi Glass, Katalin: The Iconoscope: Kalman Tihanyi and the Development of Modern Television

electric charges. The Increase within the semiconducting layer is determined by the dielectric constant (relative permittivity) of the given material. Thus In the case of glass having a dielectric constant of 5, and mica having a dielectric constant of 7, a five-fold respective seven-fold Increase of charges will result. The insulating layer used in the first storage tubes was glass, lacquer, or vitreous enamel; In iconoscopes, mica. In addition, storage technology provided: — ..electrostatic focusing," that is improved picture definition through an increase in the number of picture elements, achieved through the ..thinning" or concentration of the cathode beam into a very fine spot by having it pass through a ..sleeve" of opposing electrical field that prevents diffraction. Thus it is the size of the scanning spot rather than the physical subdivision of the photosensitive layer that defines the size of the individual picture elements, and in turn the number of lines. [Iconoscopes, according to Zworykin's 1934 paper, were good up to 500 lines, while the system demonstrated by him in July of 1930 was based on 80-line scanning (29)]; — ..single-sided scanning," characteristic of the first iconoscopes, made possible by a reflecting image carrier, and the cathode beam striking the front or photosensitive side of the screen at a 30 degree angle, which in turn was made possible by the elongated neck, the adapter tube, placed at this angle in relationship to the body of the tube. The patents of Kalman Tihanyi A thorough study of the contemporary patent literature reveals that the concept of storage and the detailed description of the technology which already utilizes the storage effect, as characterized above, was first disclosed by Kalman Tihanyi in his T 3768 Hungarian patent, filed on March 20, 1926. Although „singie-sided operation" would be added in the inventor's further refined 1928 applications, in this patent Tihanyi describes all elements and the mode of operation necessary for the implementation of the storage effect within television transmission and receiving systems. Ha defines the task he set for himself as follows: „ln order to solve the problem of electronic television, primarily a new system is needed, which extends the life cycle of the picture elements themselves at least to 1/100 s, but preferably to the maximum 1/10 s, that is for the life cycle of a picture, so that at the same time the electric pulses of a given life cycle suffice for their control".