The motion picture projectionist (Nov 1931-Jan 1933)

12 Motion Picture Projectionist November, 1931 Televised Motion Pictures We people of today are living in a fast moving era. Those among us who are inclined to be satisfied with our present position in the scheme of things are very apt to be startled out of our lethargy to find the present has passed and our position along with it. Since the advent of television, there has been much speculation as to whether this latest development in the scientific field may be adapted to motion pictures and, if so, how the adaptation will affect the industry. In the ensuing article, Mr. Replogle describes what has already been accomplished toward the televising of motion pictures. The facts as presented should prove of interest and of service. — The Editor. THAT type of partnership found over and over again between established and struggling industries— a partnership seemingly between potential competitors but ac Fig. 1. Projector, Threading Side tually made up of complementary industries and arts — is present today in the motion picture and television situation. It marks another phase of that long cycle of collaboration in which early wireless, telephone, lamp-making, radio telephone, phonograph, motion picture and finally the television arts have freely shared in developing the numerous and diversified applications of radio technique. Indeed, by loaning freely of its art to television, the motion picture industry can give the lusty infant its real start towards commercial life. Television is another form of synthesized entertainment. It takes the play, act, personality or news event and flashes it to a distant point to be reproduced as an animated or moving picture. By providing a microphone and a second transmission channel, the reproduced image may be accompanied by synchronized sound, thereby obtaining what is virtually a radio talkie. The foundation of commercial television rests on genuine entertainment value. Unless entertaining programs are made available to the homes of the land, there is little in fVice-President, Jenkins Television Corp. By D. E. REPLOGLEf terest or demand for home television equipment. We have now reached the point in television development where the program is receiving prime consideration. The technique is sufficiently advanced to provide a satisfactory vehicle for a modest program. To make that program of greatest entertainment value within the definite limitations, is our real concern. General Principles Before plunging into a discussion of the mechanics of picking up television programs, it may be well to lay a general foundation of television principles. First of all, television, for the purposes of the present discussion, refers to the transmission and reception of animated or living subjects via radio rather than by wire. In television practice, the image must be broken down into suitable pictorial units that can be readily translated into electrical terms for the purpose of transmission and reception. This process is known as scanning. Today the standard scanning system is 60 lines, which means that the image is analyzed or broken down into sixty horizontal strips, each strip being translated into electrical terms representing the lights, shadows and half-tone values. While sixty horizontal strips represent the complete image, it is necessary to repeat this process at a high rate of speed if we are to obtain the optical illusion of an animated image. For this purpose the standard scanning system flashes twenty complete pictures, each represented by sixty parallel strips or lines, each second. Necessity for Scanning Better to understand the basic idea of television scanning, supposing we are limited in our drawing talent to straight lines of varying shade. We wish to reproduce the face on a coin. If we place that coin under a piece of paper and proceed to draw sixty parallel lines across the face of the covered coin, we soon have a fair facsimile of the face on the coin. Yet we have employed only straight lines for the purpose, with varying lights and shadows and the half-tone values between. The softness of the lead, permitting of a wide latitude of shading, and the number of parallel lines employed, as well as the accuracy with which the lines meet, determines the amount of detail obtained in the replica. Television scanning is much the same idea. We analyze or scan the image to be transmitted, by means of a beam of light, which sweeps the field in sixty horizontal lines. The varying lights and shadows are translated into corresponding electrical terms by one or more photo-electric cells. These electrical terms are amplified hundreds of thousands of times and impressed on the carrier wave flung out by the transmitter. Whereas in sound broadcasting the electrical terms average between 50 and 5000 cycles for good musical quality, in television broadcasting the electrical terms or frequencies range between 30 and 30,000 or more cycles. Consequently the television transmitter, with its associated amplifying equipment, must be constructed with far greater care. Lower Wave Lengths Used The television signals, usually transmitted on lower wave lengths than the broadcast band, are intercepted by means of a special receiver. Not only must the receiver tune in the lower wave lengths, but it must admit the considerably wider signal used for television purposes. The signal is amplified, detected and amplified again. If passed on to a loudspeaker, it has a characteristic buzzsaw sound of rising and falling pitch. Usually the television signal is tuned in by means of a loud-speaker response, after which the receiver output is shifted to the radiovisor, or picture reproducing device. The radiovisor utilizes a sensitive and highly responsive light source, which translates the amplified television signals into varying degrees of luminosity. The light from the television lamp is projected by means of a scanning disc and lens system on to a transluscent screen, so that a spot of light is all that is actually on the screen at any given moment. The scanning disc with its spirally arranged holes corresponding to those at the transmitting end, causes the spot of light to weave sixty horizontal lines twenty times per second in perfect step with the transmitter, thereby rebuilding the twenty strips used in analyzing the original image. The spot of light appears as a glowing pattern of lights and shadows, due to the persistence of vision, just as the motion picture screen provides the illusion of animated pictures whereas a succession of still pictures are actually being shown. Perfect Synchronism Required It will be noted that the transmitting and receiving scanning systems must remain in perfect step. Obviously, the spot of light at the receiving end must be at the same point in the