We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
Air Cooling of Motion Picture Film for Higher Screen Illumination*
BY F. J. KOLB, JR.
EASTMAN KODAK COMPANY, ROCHESTER 4, NEW YORK
Summary — Screen illumination in theater projection is limited by a maximum radiant-energy fiux through the projector aperture. Excessive flux heats the film beyond its safe operating temperature, producing high-intensity effects in the film with loss of image quality on the screen and possible film damage. An increase of 30 to 60 per cent in permissible flux and in attainable screen illumination can be effected if film is cooled and its position controlled by high-velocity air jets directed at the film in the aperture. The high-intensity film effects are discussed and improvements in film behavior with air cooling are described.
INTRODUCTION
MAXIMUM SCREEN ILLUMINATION obtainable in motion picture projection has been limited by a number of practical factors. In recent years with the development of more brilliant light sources, faster optics, and improvements in mechanical design, it has become apparent that the film itself is one limiting factor, and that it does not perform satisfactorily beyond a certain maximum intensity of radiation. This limit has already been reached with the lamphouses and projectors currently offered for the first-run de luxe theaters.
Nevertheless, the realization that more light could be used to advantage has been increasing. Especially significant has been the growth in popularity of the outdoor theater, where the viewing conditions demand an unusually large screen area — by comparison with indoor standards — if the seating capacity is to be made large enough for the theater to operate profitably. This larger screen size should be accompanied by an increase in total screen light in order to keep the screen brightness at a satisfactory level. There have been other, although less pressing, reasons for increasing total screen light for indoor theaters, as well as for background projection, and for 16-mm projection. In these cases, little increase in screen size would be attempted, but an increase in the brightness level would improve comfort and convenience as well as permit more illumination of the surroundings.
* Presented April 8, 1949, at the SMPE Convention in New York.
DECEMBER, 1949 JOURNAL OF THE SMPE VOLUME 53 635