International projectionist (Jan-Dec 1947)

New Instant-Acting Safety Sprocket By LLOYD MANNON Member, I.A. Local Union 162 TREMENDOUS amounts of research have gone into the quest to make safer the projection of nitrocellulose film, with some phases of the problem having been overcome through the years. When nitrate film is intelligently handled and stored under normal conditions the safety factor is quite high. However, conditions are not "normal" when nitrate film is run through a projector, thus providing all the elements necessary for instantaneous combustion. Professional projection practice has ever recognized as the keystone of its safety program the need for unremitting vigilance by the projectionist should the mechanism falter for even a few seconds. A frozen projector bearing, a blown fuse, a faulty splice, or a torn film — any of these factors will precipitate a situation wherein even the quickest human reaction frequently does not suffice to avert disaster. The only known safeguard against this unhappy condition is automatic, instan W "P.N Put Greater Showmanship into Your Marquee with * nI/ y Check these 7 Outstanding Features '1^ DESIGNED FOR GREATER SHOWMANSHIP © NEW RADIANT COLORS A THIRD DIMENSIONAL EFFECT Q EASY TO SERVICE © © BUILT TO LAST MAXIMUM LEGIBILITY A EASY TO INSTALL Distributed Exclusively by NATIONAL EIDGCEOaECDZa Division of National « Simples *Zivd*totth,lnt. » / "or s'/x x*W 'a NEGATIVE CARBON ALIGNMENT for the PEERLESS MAGNARC LAMP • Huff's Negative Carbon Alignment installed on your Magnarc lamp will cut carbon consumption • To operate — simply use the two adjusting screws to raise or lower, or move the carbons sideways • Pays for itself with savings and results. EASY TO INSTALL . . . EASY TO OPERATE Only $15 Each See your local supply dealer or write direct to HUFF'S, INC., 659 W. Jefferson, Los Angeles, Calif. How the Automatic Safety Sprocket achieves fireproof protection. taneous control of the light and its intense heat which creates the danger. This entails the use of a control device that will act before the film can ignite. Basically, this means instantaneous cutoff of the light beam by means of positive dowser control. Various Controls Advanced Such a control means is now available, but before detailing its construction and action it might be interesting to review several of the efforts made through the years to establish such a safeguard. A device patented in 1911 utilized a governor which, driven by the film, actuated the fire shutter. In 1916 D. D. Daniel applied for a patent on an unit which, using trip arms, had as one of its principal objectives "improved means for making motion picture machines entirely safe from the dangers of fire." A patent was issued in 1919 for a device which by means of switches and relays would purportedly extinguish the arc, ring a warning bell, stop the projector, and perform other little chores. The trip-arm devices was improved in 1927 to include a trip on the upper loop, a modified form of which means is used on certain projectors today. Cite Electronic Applications Electronics edged into the picture in 1932 when a patent issued covering the use of a beam of light to actuate a photocell which kicked a relay and operated a safety device. In 1934 a device was introduced which utilized sprocket hole frequency to operate a "safety" unit. Other units used "safety rollers" on belts, centrifugal switches were developed, and a score of even less plausible means were pressed into service. None of these devices were successful because they failed to meet the basic 32 INTERNATIONAL PROJECTIONIST • February 1947