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1948-49 Theatre Catalog, 7th Edition, Page 343 (330)

1948-49 Theatre Catalog, 7th Edition
1948-49 Theatre Catalog
1948-49 Theatre Catalog, 7th Edition, Page 343
Page 343

1948-49 Theatre Catalog, 7th Edition, Page 343

Theatre Dimmers

Analysis of All Available Theatre Types and Their

Recommended Installation and Maintenance Practices

The primary purpose of the motion picture theatre is to present the pictures distinctly and efficiently under pleasing and comfortable conditions. These requirements apply from the moment the patron enters the lobby to the presentation of the picture in the auditorium. The selection of pleasing decor, comfortable seats, good ventilation and last but not least, good lighting, are essential to the success of the theatre.

Good lighting involves, first, the installation of proper and adequate lighting instruments and fixtures, and second, means of adjusting the tone, quality, and quantity of light. The change in auditorium lighting intensity before and after the show and during intermission to the low level of picture lighting is an elementary requirement, but the adjustment of proper lighting intensity begins in the lobby and ends at the screen.

A gradual transition from the outdoor intensity to the auditorium lighting level is necessary to prevent eyestrain, discomfort and to prevent accidental falls and injury to the patrons. As the outdoor intensity varies from day to night, from season to season, and with the weather conditions, the inside intensity should be adjusted accordingly.


Ward Leonard Electric Company, .Iuounl Vernon. N. Y.

Today the word iitheatreii no longer applies solely to the presentation of drama, but covers a wide variety of structures designed for the entertainment and education of people. By far the greatest number in any one class is the motion picture theatre, of which there are many distinct types varying from the large presentation houses to the small news-reel theatre. In all of these there is a common necessity for adequate and properly controlled lighting.

The addition of color in the lobby lighting is most desirable. A warm, cheerful interior is suitable on a cold, stormy day, while a cool light makes a hot day more endurable. Likewise, in the auditorium, variations in screen intensities with the different pictures comprising the program require adjustment of

BELOW. a small individual resistance type dimmer suitable for efficient control of theatre lobby lighting.

the picture lighting to prevent objectionable contrasts. The brighter the screen, the higher may be the picture lighting intensity.

The theatre dimmer is the device designed especially to provide the adjustment of these lighting intensities as required for any particular condition. As these requirements are present in every type of motion-picture theatre, it is essential that some type of dimmer equipment be installed so that every theatre operator can provide proper, well balanced, comfortable illumination for his patrons.

Types of Theatre Dimmers

There are three basic types of theatre dimmers, namely: the resistance type, the Autrastat (autotransformer) type, and the reactance type. All of these have their particular features which make them more or less desirable for particular types of installations.

The resistance dimmer consists of resistance wires attached to brass contact buttons over which a moving contact arm passes in operating the dimmer. All of these are imbedded in Vitreous enamel to protect the wire, and are supported by a steel stamping. A reduction in light intensity is obtained by introducing more of the resistance of the dimmer in series with the lamps, causing a voltage drop on the dimmer and reducing the voltage applied to the lamps. The energy consumed by introducing this voltage drop is dissipated as heat.

The amount of dimming will depend on the value of the lamp load connected to the dimmer. It is therefore essential with a resistance type dimmer, that it be properly loaded to secure the maximum range of light control. Ratings are available in single units up to a maximum of 3600 watts. For lamp loads of greater value, resistance dimmers are connected together mechanically but are electrically independent, and the lamp load must be divided so that each dimmer plate carries its proportion of the total load. The resistance type dimmer is the only one of the three types that is suitable for use on either direct or alternating current. Therefore, on direct current installations the resistance type dimmer must be used.

The resistance type dimmer is the lowest in cost of initial installation. Howover, due to the fact that the reduction in voltage results in a loss of energy in the form of heat, the overall efficiency of the lighting system is relatively low.

The Autrastat (autotransformer) type of dimmer is essentially a continuously tapped transformer with the taps carried out to brass contacts over which a contact arm with metallic shoes moves in the operation of the dimmer. The

1948-49 Theatre Catalog, 7th Edition, Page 343