Ficheiro:John_Logie_Baird_and_television_receiver.jpg
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Resumo
DescriciónJohn Logie Baird and television receiver.jpg |
English: Scottish television pioneer John Logie Baird (left) and his television receiver. This was one of the world's first television systems, with which Baird demonstrated transmission of moving images in 1925. The transmitter consisted of a spinning disk with 30 lenses in it which focused light from a spot on the image onto a selenium photoelectric cell. As each lens swept across the subject the photocell produced an electric signal which varied with the brightness of the subject at each point along the scan line. In the television receiver shown here, the video signal from the transmitter is applied to a neon lamp behind another spinning disk with holes in it. As each hole sweeps in front of the lamp it reproduces a line of the image. Baird, left, holds a control with which he adjusts the speed of the disk to synchronize it with the transmitter disk. The reproduced image, visible at right was a dim orange, composed of 30 scan lines, just enough to recognise faces. Because human faces did not have enough contrast to show up well, Baird used ventriloquist dummies in his first demonstrations, making them move and talk for the camera. The image shows his partner with two dummies on his lap. The television image shown was probably retouched in this photo. |
Data | |
Orixe | Retrieved August 15, 2014 from Orrin Dunlap, Jr., "The Televisor" in Popular Radio magazine, published by Popular Radio, Inc., New York, Vol. 10, No. 7, November 1926, p. 668 on AmericanRadioHistory.com. |
Autoría | Orrin Dunlap, Jr. |
Licenza (Reuso deste ficheiro) |
This 1926 issue of Popular Radio magazine would have the copyright renewed in 1954. Online page scans of the Catalog of Copyright Entries, published by the US Copyright Office can be found here. [1] Search of the Renewals for Periodicals for 1953, 1954, and 1956 show no renewal entries for Popular Radio. Therefore the magazine's copyright was not renewed and it is in the public domain. |
Outras versións | The transmitter that produced this image is shown in John Logie Baird and Stooky Bill.png |
Licenza
Public domainPublic domainfalsefalse |
Esta obra está no dominio público xa que foi publicada nos Estados Unidos de América entre 1929 e 1963, e aínda que puidese ter ou non un aviso de dereitos de autoría, os dereitos non se renovaron. Agás que o autor leve falecido o período de tempo requirido, mantén os dereitos de autoría naqueles países que non aplican a regra do período máis curto para obras nos Estados Unidos, como o Canadá (70 pma), China continental (50 pma, non Hong Kong ou Macao), Alemaña (70 pma), México (100 pma), Suíza (70 pma), e outros países con tratados individuais. Vexa Commons:Hirtle chart para máis explicacións.
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