Boxoffice (Jul-Sep 1962)

LIQUID' GATE -SHARP FOCUS Continued from preceding page combination of vacuum and air jets. Air is applied to the surfaces of the film through slits with a 0.010-inch opening extending the full width of the film. The slits are located in the surfaces of the passage just below the vacuum chamber, and are directed so as to scrub the liquid off the film. The air flow maintains the film away from the walls of the passage and also supports the columns of liquid on the film. The liquid removed from the film is returned to the supply reservoir. Any residual liquid is removed and the film will emerge dry from the bottom of the gate assembly above the intermittent sprocket. During normal operation of the projector, the film is immersed in methyl chloroform less than one-fourth second. After this time, the vacuum squeegee and air knives at the bottom of the film trap remove the surface solvent, leaving the film without any visible droplets or surface layer. The film then passes through the free loop and the optical soundhead, allowing seconds additional for evaporation of absorbed solvent, and finally winds up on the takeup reel as dry as it was before going through the liquid gate. After much research, it was found that methyl chloroform is the most desirable to use in the liquid gate. Consideration was given to fire hazard, evaporation and toxicity before final selection was made which was the best solvent to use. Of course, there is a real corrosion hazard even with methyl chloroform unless it has been formulated with suitable inhibitors. The inventors worked out a suitable formula. We have endeavored to give you fairly complete details about this new gate and we think it is very interesting about what the gate will accomplish. A further dramatic effect of the liquid gate is the removal of support-face scratches from the projected image. It is understandable, the elimination of these distracting and objectional scratches greatly enhances the screen image quality and further improves the picture so that it is more pleasing to the eye. Incidentally, the liquid exerts a cleaning action on the film, and much of the loose dirt is removed from the film surfaces. Again, the removal of dirt from film further enhances the quality of the screen image. NO TROUBLE WITH GOOD SPLICES More evidence of the reduction of the heat load on the film shows up in the lowered blistering tendency of black-andwhite film. Samples of black-and-white film were projected in the liquid-gate system at a projection light intensity 20 per cent higher than that sufficient to blister the same film in a standard gate. No blistering whatsoever was observed. No doubt higher intensity than used in the tests could be used and very likely no blistering would result. No adverse effects have been observed on curl, brittleness, dye stability, or perforation life of films projected in the liquid-gate system. Credit for considerable of the above data is herewith given to the editor of SMPTE Journal; Engineers John R. Turner, Philip A. Ripson jr., Frederick J. Kolb jr., and Eric A. Yavitz. Photos, permission of SMPTE. The inventors thought at first that the liquid gate might be hard on splices because of the narrow clearances involved. This was not the case. If the splices are properly made, they will go through without pulling apart or any damage. Poorly made splices (thick, loose-edged, or poorly aligned) are more likely, it was proved, to snag and break in the liquid gate than in a standard gate. But one should always make good splices regardless of the type of gate used because a poorly made and aligned splice will break or tear apart in any type of gate. A STUDY OF STRIPING SYSTEMS The effect of liquid-gate projection on magnetic-striped films has not been fully determined yet. Past experience has indicated that methyl chloroform may soften or partially remove some magnetic tracks. However, the engineers did project a number of magnetic-striped, prints with no physical damage to the track and with no perceptible signal loss. A study of the various striping systems will probably be made by the inventors to determine if any particular type would be damaged, and steps made to formulate a liquid to be used that will not damage the tracks of magnetic films. At the present time it is possible, then, that the effect of liquid-gate projection will vary among different stripes and there may be a preferred magneticstripe formulation or some changes made in the liquid used in the gate. Because of the wonderful improvement in the projected image, the writer sincerely hopes that steps will soon be made to place this gate on the market. 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