belinographe: BEL-1; Amateur
ID: 381026
This article refers to the model: Bélinographe pour amateurs BEL1 (Belin, Édouard (Télétype); Paris, Rueil-Malmaison)
belinographe: BEL-1; Amateur
04.Jul.15 09:21
1619
The Bélinographe, named after its inventor Edouard Belin, is a device to transmit pictures or documents by telephone wire or by radio waves. The Bélinographe is a predecessor of the modern fax machines.
Scanning and sending: The image to be transmitted is wrapped around a cylinder and scanned by a pulsating and focused light beam (dot 0,25 mm). The beam is reflected by the image into a photoelectric cell. By revolving the cylinder and moving the light beam and photocell from one end of the cylinder to the other, the entire image is scanned in helical form, a line per revolution at a time.
After being reflected off the picture, the pulsating beam's intensity is a measure of the brightness of the area under focus.
The light beam is pulsating at a constant frequency by turning a perforated disc in front of the light source. This pulse is necessary in order to get a constant frequency to transmit. Otherwise the signal frequency generated by uniformly coloured areas in the image would be too low to transmit and/or pass the amplifiers. The pulse frequency is between 1000 and 1500 Hz.
Receiving and reproducing: At the receiving/reproduction end an identical and synchronous helical movement is performed by a metal stylus moving over a sheet of paper wrapped around a revolving cylinder.
Two distinct reproducing systems were applied:
- For amateur or primitive systems, electrochemical processes were in use. The paper has to be impregnated with a chemical solution in order get a color change by the electrolytic effect on the spot where the electrical current passes, where the color change is proportional to the current intensity. This effect only works when the current always flows in the same direction, hence the need for a rectifying amplifier between the wire/wireless receiver and the image reproducer. More details on the needed chemical solution can be found in the literature mentioned on this page. Attention: explosion- or health hazard when manipulating chemicals!
- For industrial systems, photographic processes with sensitized paper were used.
The cylinder from the reproducing unit is synchronised at the beginning of every revolution by a pulse coming from the scanning device. In case of a common mains grid for both sending and receiving units, the cylinder motors can be of the synchronous type where the movement becomes synchronous automatically.
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