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It didn’t happen overnight

Every image we see with our own eyes is made up of variations of light intensity (tones) and wavelengths (colour). Light is reflected from what we are looking at to millions of tiny filaments in our retinas. From there, each “bit” of light, in the form of an electric current, is sent through the optic nerve to the brain. The brain co-ordinates these “bits” and we see the total image. At its most basic level television too gathers “bits” of light, organizes them, and sends them to your television set where they are reassembled and appear at the click of a button.

Television was not invented by a lone genius in a moment of inspiration. It evolved over decades through the contributions of many. The early contributors to its development were visionaries frequently working alone or with a few colleagues, without big laboratories or big money. These television pioneers struck out in two different directions: mechanical and electronic. Electronic would ultimately win, in large part due to later work by large corporate research laboratories, but in the beginning the mechanical approach had the advantage because of its greater simplicity.

Mechanical era

In 1884 Paul Nipkow, a young German scientist, was the first to try to transmit a moving image along wires. His theory combined two important principles: the photoelectric effect, discovered by Joseph May in 1873, and the persistence of vision. Persistence of vision is the phenomenon by which the brain continues to “see” an image for a split second after it is gone, so that a series of separate but rapidly changing images are perceived as continuous.

(Fig.1)
Nipkow scanning disc (690981), used to break an image into a series of lines. (CSTM/Peter Lindell)
Nipkow’s breakthrough was the “scanner.” He punched holes in the shape of a spiral in a metal disc. As it rotated between the subject and a light source it broke down the image into a series of “lines” of varying intensity. These lines, converted into electricity by a photoelectric cell, were sent to a receiver. There, a light reacted to the changing signal, shone through another disc rotating synchronously and created a series of images. Nipkow’s discs scanned 24 lines per picture and rotated 10 times per second. The Museum’s collection contains two examples of scanning discs (701455, 690981*) as well as components of a mechanical television camera (700232).

The first television system to be used for regular broadcast was developed by John Logie Baird. It was based on Nipkow’s disc with a transmitter and receiver built around it. In 1926 the Britsh Broadcasting Corporation (BBC) transmitted his 50-line picture signals, the first experimental TV broadcast in Britain. Baird improved his system bringing it to a peak of 240 lines and 25 pictures per second. Using his equipment, the BBC inaugurated a television service in 1932.

(Fig.2)
Mechanical television (691044), designed by Alphonse Ouimet, Montreal, 1932. (CSTM/Peter Lindell)
In 1931 radio station CKAC in Montreal broadcast the very first TV signals to go on the air in Canada. The picture was red and black and about 40 mm by 40 mm in size. A year later, Canadian Television Ltd (CTL) was founded by Douglas West. In July of that year, with Leonard Spencer, Chief Engineer of CKAC, West produced Canada’s first live TV broadcast: a violinist, a singer and a cartoonist. They continued to broadcast programs twice a week but there were only about twenty receiver sets and the experiment proved to be ahead of its time. During its short life CTL hired a young engineer, J. Alphonse Ouimet, later to become President of the CBC, who built a mechanical receiver that is now in the collection (691044).

 

Electronic era

In 1908, A. A. Campbell-Swinton, a British engineer, proposed a scanning system that used an electron beam generated by cathode-ray tubes (CRTs) in both the transmitting and the receiving ends. As early as 1897, Ferdinand Braun had directed a stream of electrons at the fluorescent inner surface of a CRT. He found that he could deflect the spot of light created on the face of the tube using magnetic fields outside the tube. This was the basis of the oscilloscope and later, the picture tube. The Museum’s collection contains many examples of CRTs.

A viable electronic system would also need a camera tube. The race to create this essential component had three main competitors, the British team at EMI led by Isaac Schoenberg, and in America, Vladimir Zworykin at Westinghouse and later RCA (Radio Corporation of America), and Philo Farnsworth, an independent inventor.

(Fig.3)  Iconoscope tube (670824), ca 1940, used in first commercial TV cameras in North America. (CSTM/Peter Lindell)

Zworykin demonstrated his solution, the iconoscope (670824) in 1928. Farnsworth patented his image-dissector in 1930. In 1932 EMI introduced the emitron camera tube, which out-performed Baird’s mechanical system. The electronic die was cast.

(Fig.4)
EMI receiver (750621), 1938. Britain launched the world’s first regular electronic television service in 1937. (CSTM/Peter Lindell)
In Britain in 1937, a system built around EMI’s emitron provided the first regular high definition (for that time) television broadcast service in the world. The British standard was set at 405 lines and 25 pictures per second (replaced by a 625 line standard in 1964). The museum has one example of a 1938 EMI receiver built to the 405 line standard (750621).



(Fig.5)
RCA TRK-12 receiver (710663), introduced at New York World’s Fair, 1939. (CSTM)
Of the two American devices, the iconoscope and the image-dissector, the iconoscope proved more workable. In 1939, RCA’s National Broadcasting Company (NBC) kicked off experimental broadcasts with a live program from the New York World’s Fair. The Museum’s collection contains an RCA TRK-12 receiver from this period in which the tube is vertical and the image is reflected in a mirror for viewing (710663). Our example was used by the National Research Council of Canada for wartime radar research.

In 1941 the United States government set the American broadcast standard at 525 lines and 30 pictures per second (where it remains today) but the Second World War halted commercial development. Regular scheduled broadcasting began in the United States in 1947 and in Canada, using the same standard, in 1952.

* The numbers in brackets are the accession numbers of artifacts held by the Museum.