TELEVISION PROBLEMS

Sun (Auckland), Volume III, Issue 623, 27 March 1929, Page 14

TELEVISION PROBLEMS

CHANCE FOR INVENTORS On any radio receiving set the substitution of an electric lamp for the loud speaker v. ould make the signals visible instef.U of audible. The set owner would nee the flickering of a lamp in place of hearing the vibration of a diaphgram. At the receiver, in place of a loud speaker, a lam’p flickering with the varying signal Intensity reproduces the reflected Tight from the original subject. It j/rovides the gradations of light and .uhade that enable us to distinguish form. All that rumains is to arrange the series of ligfit flashes over a surface or area coT.Tesponding to that occupied by this object. That is, a picture must be formed out of this succession of light and shade just as the artist, forms a picture from a succession o f brush touches on a canvas. This is done at the receiver by another scanning disc with the same number of hales as that at the transmitter, and running at the same speed. It may be smaller or larger than the transmitter disc, and the j object Is reproduced on a smaller or ! larger canvas in proportion. HOT PLATE IS CANVAS The canvas is the glowing plate of the lamp, and this plate must be as large as the image is to be. As the transmitter disc rotates, the receiver disc explores a line across the object, and lets the beams of light fall in succession on the photo-electric microphone, so the receiver disc has a hole which explores a line across the glowing piate of the lamp, and It is seen bright in one spot and brighter in another, as it flickers. There must be perfect ss'nehronism between the tw r o discs, so that the j line viewed across the glowing plate varies in light intensity exactly as | does the line explored across the ob- j jeet. A succession of such lines will

make an. image having the same gradations of light and shade as the original object had. The succession of impulses are spread over a surface to create a form. It must be done quickly enough so that the eye does not dwell on the mechanics of the process, but sees only the light flashes in their proper place, rather than as a sequence. SPREADING OF SIGNAL The problem of television to-day lies wholly in this spreading out of the signal. It is possible to send a succession of signals fast enough if the wave-length on which to transmit can be selected without legal limitations. It is not now possible to spread out this succession of signals over a large surface fast enough for the eye to see the individual dots or fluctuations and recognise a complete image. It can be done on a tiny scale with scanning discs. Even then it is hard for the receiver disc to be held in exact synchronisation with the: transmitter disc except by the most skilful operator. It is necessary to find some automatic way to hold the two discs together, and then on this tiny scale the present type of experimental television will be commercially feasible in a modest way. Real television, by which one can see fights and games, awaits a new spreading out method. The transmission is possible. The manufacturers have the transmitter and the photo-electric microphone. They can probably build a receiver, and there Is the silent, flickering lamp to make the signal visible. The thing that must be found is some way to present each portion of the view In rapid sequence before tte microphone, and to take this sequence of impulses on the receiving end and coil them up to form an image. When that can he done, television will have arrived. Someone may conceive of the method to-morrow, or it may not be discovered during the present century. No man can predict when inspiration may visit him.