Tech Directions - October 2007 - (Page 10)

technology’s past Dennis Karwatka d.karwat@morehead-st.edu Paul Nipkow and 19th Century Television Technologists began investigating the concepts of television before electronics was even discovered. They first worked at sending a nonmoving image down a wire. The idea was to break it into small sections. At the destination, the pieces would be reassembled, much as with a jigsaw puzzle. Paul Nipkow was a young Polish-German university student when he developed a television transmission and reception method based on a spinning disc in 1884. Nipkow was born in Germany in 1860, but his birth city is now Lebork, Poland, near the Baltic Sea. He studied telegraph and telephone communications at a technical high school. Nipkow was an electrical engineering student at the University of Berlin when he visualized his scanning disc theory for transmitting video images. He thought that the most practical technique would be a system based on pulses. At home during the Christmas season of 1883, he conceived the idea of using a disc onto a selenium photocell. Light hitting the selenium cell through lenses produced a small voltage that varied with the shading of the subject. The electrical power traveled along a wire to its destination. To see the transmitted image, the pulsing voltages powered a small bulb. Its dim light passed through another disc that was synchronized with the first, and the picture would Paul Nipkow appear on a flat surface. At least that was the idea. It was good enough in 1884 to earn Nipkow a German patent that he titled Electric Telescope. Nipkow's invention took the first tentative steps toward a system that came to be called mechanical television. His idea was ingenious, but he Undated Nipkow scanning system photograph is undated and not attributed to him. The holes in the disc are large to reduce weight. The image-scanning holes are in a shallow spiral near the edge and too small to see. Although Nipkow showed technologists the way, his system was far from practical. He probably did not construct a prototype, but his technical logic was sound. If he had built a prototype, the output image would have been dim, jerky, and barely legible, with a resolution of 18 vertical lines. Needing to earn a living, Nipkow spent most of his professional life as a railway engineer designing signaling equipment. He did no Rendering further work with by Tim Harmon television. However, one me(1860-1940) chanical television system evolved during Nipkow's lifetime and achieved some success. Using a Nipkow disc, John Logie Baird (1888–1946) of Great Britain sold as many as 20,000 of his Televisors in the 1930s. That encouraged Germany in 1935 to name its public television station the Paul Nipkow Fernsehsender (television station). Nipkow was also made honorary president of the German Television Society. He died in 1940, and the German government gave him a state funeral. Some modern reflected-light microscopes use a variation of the Nipkow disc. Several thousand points of light can simultaneously illuminate a single specimen. This provides the effect of many individual microscopes. References Day, Lance, & McNeil, Ian. (1996). Biographical dictionary of the history of technology. Routledge Press. Hubbell, Richard W. (1942). 4000 years of television. G. P. Putnam's Sons. with holes in a spiral pattern. Light that passed through the holes while the disc rotated could scan an object and divide its image into pulses. Nipkow's original disc had 18 small rectangular holes in a shallow spiral near the edge. Rotating at 600 rpm, the disc was positioned between the subject and a bright light. The light scanned vertical sections of the subject and pulsed 18 times couldn't build a complete system. The supporting technology was not yet available. One obstacle was that the selenium cells were slow to respond to light pulses. Another was that Nipkow had no way to amplify the electrical power from the selenium cells. The output image probably would not have been visible. The Nipkow equipment shown in the Dennis Karwatka is professor emeritus, Department of Industrial and Engineering Technology, Morehead (KY) State University. 10 techdirections ◆ OCTOBER 2007

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Tech Directions - October 2007 Technically Speaking Contents Direct from Washington The News Report Technology Today Technology’s Past Mastering Computers Rock Your Classroom!—Use Subwoofers to Teach Electricity and Science Sure, They Can Build It, But. . . . Manufacturing Students Need Process Planning Skills Teach Graphic Design Basics with PowerPoint Free Teacher Resources Product Central More than Fun

Tech Directions - October 2007

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