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1953-54 Theatre Catalog, 11th Edition, Page 287 (251)

1953-54 Theatre Catalog, 11th Edition
1953-54 Theatre Catalog
1953-54 Theatre Catalog, 11th Edition, Page 287
Page 287

1953-54 Theatre Catalog, 11th Edition, Page 287

and odors to the outside air. This may be accomplished by means of an adequate forced-draft ventilating system; this system may also serve to exhaust normally, the gases and carbon ash from carbon arc enclosures. A natural gravity vent, with adequate cross-sectional area extending through the projection room ceiling directly to the outside air, should also be provided as protection in case of failure of the electricity supply service.

Proiec'I-ion Room Dimensions

Consideration should be given to the dimensions of the projection room in order to provide normal operating safety factors for the projectionist. The room should not be less than 12 feet between front and rear walls, in order to save sufficient working and free walking space around all the equipment. The rewind tables should be located at the rear wall equi-distant from the two projectors. The space between projectors should be 60 inches at the lens centers, and there should be a clear space from the lens centers of 48 inches both to the right of the righthand projector and to the left of the lefthand projector. A modern design for the rewind table includes space beneath the table top for locating approved-type film containers, supported several inches above the floor.

In order to deliver on the screen the high quality performance expected from the projectionist, he must at all times, while on duty, be reasonably calm and alert, both mentally and physically. These considerations, as well as those of common decency, call for providing adequate modern toilet facilities, and a lavatory with both hot and cold running water in Well-designed theatre projection rooms.


The installation of theatre television equipment has introduced problems not heretofore present in providing motion picture screen presentations. Essentially,

THE CAMPUS. Los Angeles. offers a fine example at roomy. well planned. safe projection booth.


the equipment purchased by the theatre owner for such an installation consists of three major items: (a) a high-voltage supply unit weighing 800 pounds and providing 20,000-volt and 80,000-volt output circuits; (b) video control amplifier units mounted on conventional racks and weighing 1200 pounds; and (c) a picture projection unit with its mounting trunnion, weighs 400 pounds. This by no means small extra weight of over a ton, introduces a definite safety hazard to the building structure in many instances. Structural loading factors need to be thoroughly checked before installation of such massive equipment.

Location of Equipment

Because of the high potentials pr0< duced by the voltage supply unit, it is essential that it be located in a separate fireproof room with the entrance door closed and locked at all time. It is preferable to locate the unit as near as possible to the optical barrel which

A PROPERLY equipped projection booth and a calm proiectionist. are the ingredients that keep bro and disaster risks in theatres to a minimum.

encloses the picture projection tube, in order to reduce the required length of special 80,000-volt cable which connect to the second anode of the picture tube.

The video amplifier unit is mounted on two racks occupying a fioor space 40 inches wide and 18 inches deep, extending a height of 64 inches in the theatre projection room. It contains a television receiver, monitor panel, control panels, low-voltage power supplies, and other miscellaneous operating units. While required projection room space is not large, the room dimensions should pro vide enough to avoid overcrowding, and consequent reduction in normal operating safety factors.

The proper location of the picture projection tube and optical barrel is very important from the viewpoint of safety to the public, and it is also a very important factor in securing best projection quality. The nominal ffthrow" from the projection unit to the screen is 60 to 65 feet. In a typical installation, a heavy steel platform was installed for mounting the optical unit. This platform was mounted on the front face of the first balcony rail in such a manner as to preclude any possibility of unauthorized persons having access to, or coming in contact with the projection tube, or any of its high-voltage terminals. In this position, the tube and optical barrel projected a 1-5 by 20 feet picture on the screen at a ffthrow" of 62 feet. In theatres having no balconies the projection unit must be supported from the door or ceiling and, as in the case of balcony support, the mounting structure must be adequately designed to eliminate any possibility of either electrical or mechanical hazards to theatre personnel or audience. The unit should be enclosed in such a manner that any corona or arcing due to dampness is not visible.

Presently available direct projection television equipment is very well designed from the viewpoint of having adequate
1953-54 Theatre Catalog, 11th Edition, Page 287