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1945 Theatre Catalog, 4th Edition, Page 586 (558)

1945 Theatre Catalog, 4th Edition
1945 Theatre Catalog
1945 Theatre Catalog, 4th Edition, Page 586
Page 586

1945 Theatre Catalog, 4th Edition, Page 586

front of the balcony) or, alternately, in back of the screen where there has been enough space, for rear projection.

In general the equipment is divided into tWo parts: (1) the projector itself, with cathode-ray tubes and lenses and radio receiver, amplifier, and synchronizing equipment, together with controls of brightness and contrast; and (2) the high-tension equipment which has to be located under the auditorium or under the stage or at the side of the theatre in safety cages. Where theatres have been equipped to operate on a commercial basis, the local regulations for safety have had to be observed, and the principal points needing attention arise from the fact that very high voltages are used in the projector and that the cathoderay tubes, operating at such high volt ages, have been liable to generate x-rays. Th'e ever-present danger of electrical shock has been eliminated by the providing of electrical interlocks and other safety features, and the generation of x-rays by the surrounding of the cathode-ray-tube compartments by shielding sheets of lead. So far these precautions have been sufficient to obtain the approval of the local authorities, but, no doubt, in course of time, the only satisfactory position for the television projecs tor will be in the projector booth, where all essential equipment for projection will be completely divorced from the auditorium. The installation of equipment will be subject to the usual regulations for fire prevention and safety. Reference has been made to the screen on the stage. To obtain every ounce of

FIGURE 9.-This is the AFIF high-definition television projector developed by the Swiss Federal Institute of Technology in Zurich. The arc lamp on the left projects through the liquid-film, cathode-ray-controlled light valve (center) and the projection lens (right) into the auditorium. The work on this. equipment has been going ahead during the war, and it is anticipated that a picture of better than 250 lines will be available very soon.

brightness it has been found necessary to develop screens with a much higher reflecting power than the normal mattewhite screen. Thus, provision may have to be dropped from the fly loft when the program changes over from film to television presentation.

Operation in Theatres

So far, the cathode-ray-tube type of equipment has been partly of an experimental nature, and this has necessitated that it should be operated only by experts who, through having taken part in the practical deveIOpment of the equipment, are fully conversant with its servicing and maintenance, but in due time the equipment will assume a form where it can be operated and maintained by technicians of average'skill. The presentday projectionist needs to cover a fairly wide field of experienceethe handling of film, the maintenance of mechanical equipment and of the sound amplifying system, and the care of arc lamps and of medium power generators. In the future, his training will tend much more in the electronic direction, where he will have to be conversant with television theory and practice, and with the operation of the controls associated with the high-voltage cathode-ray-tube projector. The projectionists of the key theatres, where television was about to be installed, were required to attend a special course in electronics, with opportunities of practical experience in the adjustment of circuits and in the setting up of the cathode-ray tubes and optical systems. Today, the average projectionist is mainly concerned only with the adjustment of focus in the projector for the picture, and of volume level in connection with the sound reproduction. Now, he will have to learn how to achieve correct centering of the picture, correct contrast and definition, so that a high-quality result can be maintained throughout the program. No doubt much of his work will be simplified for him by means of automatic control, but backing him up in his job there will need to be a well organized service of highly skilled maintenance engineers, and a regular daily routine testing to make certain that programs run smoothly and without a hitch.

For instance, in the early days of television projection, cathode-ray tubes will not have a particularly long life, possibly not more than 1,000 hours, and the projectionist will have to be skilled in the rapid replacement of these tubes in the equipment.

The projection booth of the future can be visualized as having two or three standard film projectors and two television projectors, both of which latter will take up as much or possibly more room than the film projectors. Thus, architects, in building new theatres or modifying existing ones, would be well advised to prepare for the future by a1lowing plenty of room in the projection booth over and above the requirements of normal film projection. Allowance should at the same time be made for a separate room close to the projection box with safety, interlocking doors, for setting up the high voltage equipment which will be necessary. A particular

1945 Theatre Catalog, 4th Edition, Page 586