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Synchro-Lite Powered 16mm Projector
By R. E. PUTMAN and E. H. LEDERER
A new flashtube arrangement, providing projection light for television reproduction from film, is here described in detail. It assures accurate and permanent synchronization of light pulse with intermittent pulldown. Further, since both the intermittent movement and the flashing lamp are controlled by the television vertical pulse, the mechanism can readily be interlocked with other picture sources for interpolation, laps and fades. Travel ghost resulting from motion of film while the light pulse is on is made impossible by the design.
IVJLoTiON PICTURE film plays a very important part in television stations, both as to programming and as to revenue. The projection equipment used, therefore, deserves the most serious consideration and attention. Methods and devices developed for the very different purpose of projecting a motion picture before an audience are not well adapted to energizing an iconoscope.
The value of pulsed light for film projection in a television system has long been recognized. Among its advantages are very long lamp life, still frame projection without risk of damage to film, accurate control of width of light pulse, high iconoscope output, and freedom from phasing bar in the picture area.
The new Synchro-Lite* Projector to
Presented on May 9, 1952, at the Atlantic Coast Section Regional Meeting at Atlanta, Ga., by R. E. Putman, who read the paper, and E. H. Lederer, Broadcast Studio Engineering Section, Electronics Div., General Electric Co., Electronics Park, Syracuse, N. Y. This article is part of a paper presented at the Sixth Annual NARTB Conference, Chicago, April 1952. * Synchro-Lite is a General Electric trademark.
be described here was designed to offer additional advantages. Performance, accessibility and simplicity have been improved. The design permits accurate and permanent synchronization between light pulse and projector action. Drift from synchronization is eliminated. Possibility of travel ghost, resulting from film transit during the interval the light pulse is on, has also been eliminated. Interlock between this projector and other picture sources, including sources remotely located, can be accurately maintained so far as this projector is concerned, since its entire action is controlled by the television vertical pulse.
Mechanism and Lamphouse
The projector mechanism is that described by Frittsf with some relatively minor modifications. One is elimination of the projector shutter, which is not needed, of course. Another is a change in the constants of the coiled spring in the tuned coupling between the
f Edwin C. Fritts, "A heavy-duty 16mm sound projector," Jour. SMPTE, 55: 425438, Oct. 1950.
April 1953 Journal of the SMPTE Vol.60
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