Friday, August 22, 2014

Paul Nipkow and the Picture Scanning Technology

Paul Nipkow (1860-1940)
On August 22, 1860, German engineer Paul Gottlieb Nipkow was born. He is best known for having conceived the idea of using a spiral-perforated disk (the Nipkow disk), to divide a picture into a matrix of points, and became an early television pioneer.

Nipkow was born on August 22, 1860, in Lauenberg (Lębork) in Pomerania, now in Poland. Inspired by the work of Guglielmo Marconi, Nipkow began thinking about the challenge of transmitting a visual image while still a student in Germany. While at school in Neustadt (Wejherowo), West Prussia, Nipkow began to experiment in telephony and the transmission of moving pictures. It was well known that any successful transmission device required three essential components: a device to translate the visual image into an electronic impulse, a second device to reassemble that impulse into an image again, and a third device by which to transmit the impulse from the first device to the second. In 1884, even before completing his degree, Nipkow had developed and patented a transmissions system that achieved all three requirements.[1]

While still a student Nipkow conceived the idea of using a spiral-perforated disk (Nipkow disk), to divide a picture into a matrix of points. Accounts of its invention state that the idea came to him while sitting alone at home with an oil lamp on Christmas Eve, 1883. Alexander Bain, a Scottish inventor who had patented the electric clock, had transmitted images telegraphically in the 1840s but the Nipkow disk improved the encoding process. The Nipkow disk was a metal or cardboard disk that was perforated with twenty square holes arranged in a spiral so that each hole was a little closer to the center than the last. As Nipkow spun the disk, he shined a strong light through the holes and onto the subject. Because each hole was slightly offset, the image was scanned in a series of twenty horizontal lines.[1]

Nipkow's Disk from his
1884 patent application
Another important component of his invention was a selenium photocell used to transform differences in the intensity of light into electric current. The current could be transmitted to a receiver, where the image was reproduced with an identical disk that was synchronized with the first in front of a lamp whose brightness changed according to the received signal. Nipkow once used his device to transmit a visual image from London to Paris, but the system was never developed for commercial use. Ironically, at the time, investors could not foresee a practical use for it, and therefore, Nipkow received little recognition during his lifetime for the feat.[3]

Nipkow applied for a patent in the imperial patent office in Berlin for his electric telescope. This was for the electric reproduction of illuminating objects, in the category "electric apparatuses". German patent No. 30105 was granted on 15th January 1885, retroactive to 6th January 1884, the 30 marks fee being lent by his future wife. It was allowed to lapse after 15 years. Nipkow had taken a position as a designer in the Berlin-Buchloh Institute and did not continue further development of the electric telescope.[2]

The first television broadcasts used an optical-mechanical picture scanning method, the method that Nipkow had helped create with his disk. The first inventor who used Nipkow's disc successfully, creating the first television pictures in his laboratory in October 1925, was John Logie Baird. From 1937, when the infant BBC television service chose it above Baird's mechanical system, total electronic picture scanning, based on the work of Manfred von Ardenne and the iconoscope invented by Vladimir Zworykin, became increasingly prevalent and Nipkow's invention was no longer essential to further development of television. Today, the Nipkow disk is used extensively in reflected light confocal scanning microscopy to produce images that can be viewed in real time through the microscope eyepieces.

At yovisto you can watch an RCA documentary on the history of television to learn more about the invention of television and its early days.

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