The Exhibitor (1959)

I FIGURE TWO: A Iront view of the Century Mod¬ el R-31 70/35mm magnetic sound reproducer, showing the two reproducer heads, hydraulic flutter suppressor, and driven film sprocket. time the tail end of this film runs out to the time of starting threading 70mm film, only seconds will elapse. It is, therefore, entirely safe and reasonable to run a 70mm feature film with 35mm news and short sub¬ jects. The Intermittent Movement The intermittent movement, as usual, is the heart of any motion picture projector. The Century 70/35mm intermittent movement has all of the accuracy and stamina of years of experience in the design and manufacture of such units for commercial, as well as specialized, applications. The standard 70/35mm movement is a geneva starwheel and cam design, but of larger dimensions, larger shafts, larger cam pin, larger starwheel, and larger radii than any known projector for these applications (almost 100 percent heavier). Each part is the result of experimentation to find the right materials, weights, hardness, and finish to give undeviating steadiness to the picture with a reasonably long operating life. The double intermittent sprocket should receive particular mention because of the exhaustive research and testing it has re¬ ceived. Life tests have been conducted on these sprockets for the past two and half years. They are made of special duraluminum having a hardness at the wearing surfaces harder than the steel of standard sprockets. The sprockets are easily changed without removing the movement from the mechanism. They can be reversed, also, in the mechanism, and by a unique design of hub contour the concentricity of the rims and the positioning of the teeth are assured. Screen measurements indicate that picture steadiness is equal to, or better, than the best 35mm performance. No expense has been spared in making this 70/35mm intermittent out-perform any de¬ vice of its kind. It is designed specifically for use with larger films at normal and increased film speeds. All other sprockets in this projector are double (70/35mm) and made of hardened steel. The diameter and tooth shape of each sprocket has been designed for the particular job it has to do. Each sprocket is, therefore, expected to last a long time and to contribute to long film life. There has been much dis¬ cussion with many pros and cons relative to the “correct” sprocket dimensions for opti¬ mum results. Century believes, as it has for a number of years, that there is a fine bal¬ ance of design practice which dictates the exact size and shape of every sprocket for the most economical service at the highest oualitv performance. Century sprockets are designed under the strict adherence to these principles, and any deviation from these de¬ signs could contribute nothing but depreci¬ ated results. Pad Rollers Each pad roller associated with each sprocket is of the double roller type, mounted and clearly marked so that the changeover from 70mm to 35mm operation is accom FIGURE THREE: The rear view o! the Century Model R-31 70/35mm magnetic sound reproducer showing the vertical drive shaft and gear for the film sprocket, two flywheels and arm supports for the hydraulic flutter suppressor, the fourchannel and six-channel terminal blocks with two cable connectors for the separate sound systems. plished by rotating the assembly a half turn. There are three such pad rollers in the com¬ plete projector and the change can be made in less than one second per roller. A quick glance (after threading the projector) clearly indicates whether or not each roller is in proper position to run the film selected. The Film Trap The film trap shoes are hard polished chromium permanently held in an exact con¬ tour insuring the proper curvature of the film. The complete film trap is water cooled down to the mounting of the shoes, which are insulated from the water cell to prevent the condensation of water on any metal part actually touching the film and yet providing for the absorption of all radiant heat trans¬ mitted from the arc lamp. To the most minute serration of the film trap, the design prevents unwanted light reflections from the water cell chamber and yet accepts all un¬ wanted radiant heat without interference to the useful light at the aperture. The same careful physical design also ap¬ plies to either the 70mm or the 35mm film trap. Each film trap with its properly curved shoes slides out of and into the mounting on large accurately positioned gibs and is firmly and accurately held in operating position. An interesting observation of the film trap (and film gate also) discloses that they may be changed easily to operate with almost any film dimension. A word regarding water cooled film traps is not amiss in this discussion. There are two kinds of water cooling in prevalent use. These should be classified as water cooled heat shields and water cooled film traps. The object of water cooled heat shields, used on most water cooled projectors, is to absorb most of the stray heat going into the projector. These shields have nothing what¬ ever to do with the heat which destroys the motion picture film nor the operating tem¬ perature of the aperture plate. The Century 70/35mm film traps are de¬ signed to take all possible damaging heat away from the film, allowing only that heat which is inseparable from the light to im¬ pinge on the projected picture area. Century believes that, within the limits of available air blowers or economical air velocities ob¬ tainable for motion picture projectors, that there can not be any advantage in air which may circulate past the film as it is being projected. Instead, it is believed that any air which may circulate past the aperture merely serves the purpose to cool the aperture plate and that an efficient water cooled aperture plate, as incorporated in the standard line of Century water cooled projectors, and this new 70/35mm projector, reduce the damag¬ ing heat on the film to an absolute minimum without direct mechanical contact of cooled Continued on Page 60 April 1, 1959 MOTION PICTURE EXHIBITOR-1959 THEATRE CATALOG Edition 43