Technikatörténeti szemle 20. (1993)

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

the British Air Ministry (35). Negotiations with RCA continued throughout 1931, and then, for reasons that are unclear but in all likelihood included an unacceptable offer, ceased after a meeting between the inventor and RCA's European manager on or around February 4, 1932 (36). The development of the iconoscope It would seem that the search for Tihanyi began following Zworykin's move, in January 1930, from Westinghouse to the RCA labs. At that time, Zworykin resumed his television experiments, concentrating on certain new ideas regarding receiving tubes with which, according to Albert Abramson's account, he returned after an extensive tour in the summer of 1928 of Europe's television laboratories (37). (It is interesting to contemplate what Zworykin might have heard about Tihanyl's ideas in Berlin where, no doubt, he visited the same places and almost simultaneously with the Hungarian inventor.) Apparently, the ideas with which Zworykin was inspired at the Belln laboratory in Paris took shape in his November 16, 1929 application (U.S. Pat, 2,109,245) to which the canonical view attributes the Kinescope. The pivotal feature of the invention seems to be electrostatic focusing („thinning of the pencil of rays" in the 1926 and 1928 Tihanyi patents) (38). On May 1, 1930, for the first time since his 1923 and 1925 filings, Zworykin applied for a patent describing a complete television system (39). A second patent application was filed on July 17, 1930 (40). Both applications are an attempt at storage featuring two-sided targets — that is the cathode beam impinges on the back plate — and porcelain respective glass insulation. Both specify 10.000 picture elements. These applications run into difficulties at the patent office, as the examiner rejects certain claims, citing Tihanyl's 313, 456 and 315, 362 British patents, and the fact that these were „thrown open to the public in England on June 26, respective July 24, 1929" (41). Eventually, seven claims of the May application and three claims of the July application were rejected on this basis. Zworykin's first demonstration for RCA took place on July 15, 1930. According to Abramson, although it featured an electronic receiving tube, the television film transmitter was a mechanical device (Nipkow disk) and synchronization was accomplished by a mechanical impulse generator. Another more recent publication, prof. J. H. Udelson's survey of the development of television in America, confirms this (42).