The history and development of TV

About the history of television and the first TV you can find a lot of articles and stuff, but they all lie al actually, the first TV with a recorder (a prototype of the VCR) has a very, very long time, we have them all constantly uses when the dreams we see, but. don't you? ad

No, no beloved "box" we already can not imagine, and soon may our children and grandchildren it is unclear why early TV was called "the box", and it all just recently the invention resembled a huge box, well, all in good time bs

The principle of image transmission at a distance) was formulated in the distant 1880, independently by two scientists from: the American V. E. Sawyer and French Maurice LeBlanc. It was a principle of sequential scanning of different areas of the image (one after the other: and so line by line, frame by frame)

LeBlanc was guided by the principle that the human eye is able to "remember" the image some time (about 0.1 second so-called the inertia of the eye). Thus, there is no need to transfer the finished frame, it can create in our brains from separate pieces. Of course, at that time, it was possible to do only by mechanical means

But to realize the idea of transfer images in the two devices: the Converter light energy into electrical energy and the mechanism of sweep. This mechanism was invented in 1884 year and patented by the German railroad P. Nipkow. His invention, the famous Nipkow disk was a disk (about 50 cm), with evenly spaced spiral 30 small holes (about 1 mm) dq

Nipkow and his CD

Thus, when the disk rotates, each time we observe only one point (part) of the image. When the disc makes one turn, all areas of the image pass through the holes, making the whole picture. In order to realize the idea of transfer images in the two devices: the Converter light energy into electrical energy and the mechanism of sweep bw

an image on the Nipkow diskLines of the image of the Nipkow disk

The light sensor appeared thanks to the works of the Russian scientist A. G. Stoletov, the opened photoelectric effect - emission of electrons under the action of light. It was noted a special property of selenium and some other materials to change their electrical resistance under illumination: the brighter the light falling on the selenium plate, the easier it conducts

A. G. Stoletov

The term "TV", formed of two words: the Greek tele (far) and the Latin visio (vision), introduced lecturer at the Artillery Academy of Saint Petersburg, K. D. Perskiy

The first electro-mechanical television using Nipkow disk had only one photosensitive element. Needless to say that about any as it was not - it was just a play of shadows and silhouettes. It was clear that one element just do not have time to monitor changes in the brightness of the image, needed a "matrix" bc

The inventor of the electro-mechanical scanner is considered to be a Scottish engineer, D. bird

Scottish engineer D. bird

Selenium plate was divided into "pieces", the image from the lens hits it, zasvechivaya each "piece" in different ways, the stress at each site was read by an electron beam and transmitted sequentially. The Nipkow disk was rotated at a speed of 12.5 Rev/sec, the forming of 12.5 frames per second of 30 lines each (count the holes)

Receiver (electro-mechanical transmitter) had exactly the same disk (rotation speed synchronized), a lens and a lamp located behind the disk (in focus). Her glow was changed in the same way as the signal from the sensor (transmission camera) thus formed image.

Electro-mechanical transmitter

The size of this image (without additional lenses) was about 3x4 cm, of course, it wasn't enough. It was possible to increase the number of holes in the disk (100-200), but then the size of "TV" and the transmitting camera had already gone beyond all limits crazy

It was clear that mechanical unfolding has no future. In 1907, Professor of St. Petersburg Institute of Technology B. L. rozing have developed a sample cathode ray tube with a magnetic scan of the two pairs of mutually perpendicular coils (deflection system), mounted on the cylinder head. In may 1911 Boris Rosing demonstrated his invention before a scientific audience.

Cathode-ray tube of Rosing

Tube of Rosing has control of the plate d, to which is supplied a signal from the photoelectric receiver. Thus the electronic beam changes the brightness of the screen at different points, respectively, the transferred image. The number of "lines" in the frame when the scan was significantly increased. In fact, it was the first kinescope ab

B. L. Rosing

There was a second problem - the transmitter. The main difficulty lay in the fact that in scanning a transmitted image light acts on the photosensitive layer a very short time - millionths of a second. Excited while the charge is negligible increase to the value required for transmission, it was extremely difficult. Zworykin set out to create a tube with charge accumulation, and 1931 year of such a tube has been created. The inventor called it IKE (from the Greek words for "icon - "image" and "scop" - "to see")

Zworykin Iconoscope

After completion of the tests iconoscope in 1934 year, Vladimir K. Zworykin suggested an electronic television system with a resolution of 240 lines, and the following year increased the resolution up to 343 lines per frame. Thus began the era of mass television bs

Read more: tube black and white TV history with pictures

Link to this story: http://en.rem-tv.net/publ/3-1-0-36

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