Exhibitors Herald and Moving Picture World (Jul-Sep 1928)

July 7, 1928 EXHIBITORS HERALD and MOVING PICTURE WORLD 39 New Spahr Projector ELIMINATES Heating Drying Warping Buckling OF FILM Declares Enterprise President RUMORS have persisted for sometime that Enterprise Optical Manufacturing Company of Chicago, builder of the Motiograph de luxe projector, was perfecting a new machine radically different in principles and construction. Detailed announcement of this new projector is made this week by O. F. Spahr, president of the company. The new principle, as described by Enterprise, is one which operates to eliminate the heating, drying, warping and buckling of film. The following description of the new product is offered by the company: "The New Model H Motiograph De Luxe Projector is radically different in principles involved and construction than the present types of projectors employing the outside rotating disc type of shutter. It depends upon a new type of shutter of peculiar design for its important function of eliminating the heat from the film. * ^ * "The new shutter is of a horizontal or cylindrical type. It is mounted on the film gate of the mechanism and operates between the film and the light source. It differs in construction from the rotating disc type of shutter in that it has two circular vanes and is rotated on a horizontal axis. By these two vanes, the light beam is cut off in a horizontal plane from top and bottom simultaneously. This being across the narrow dimension of the aperture, results in what may be termed a "quick cut-off." Thus, a gain in illumination over the old type front shutter is accomplished. The action of the two vanes cutting the light beam simultaneously also is an advantage in that a cleaner cut-off is obtained, a more uniform distribution of the intervals of light and darkness and a smoother shutter action with entire absence of backlash travel ghost is the result. "In the second purpose, the vanes of the shutter cutting off the light and incidentally the heat between the film and the light source, it is easy to reason that since the light is cut off during the whole interval of film motion before the aperture, there can be no heating or rather pre-heating of the film before it comes to a stop before the aperture, as is the case in the old type front shutter where the full action of the light beam is operating to heat the film both during the full film movement as well as during the whole time the film is at rest before the aperture. A further cutting of the light beam during that portion of time when the film is stationary before the aperture, is accomplished at that period known as the flicker interception. Thus, it will be seen with our new shutter that the entire action of the light beam and its incident heat is cut off from reaching the film while the film is in travel before the aperture, and once while it is stationary before the aperture. The heat of the light beam is only allowed to reach the film at two short intervals, once when the film comes to a stop before the aperture and again after the flicker interception has passed and until the film starts in motion again. "An idea of the conistruction of the new type shutter may be gained from the close-up view in Figure 2 in which the shutter vanes, and construction is clearly indicated. "So efficiently has this worked out to reduce the heat at the film that actual tests conducted in our laboratory show a reduction in temperature of the film heat at the aperture as follows: Comparative Temperature Tests on Mcdel H Motiograph De Luxe Projector — in Comparison with Regular Projector with Old Type Outside Revolving Disc Shutter: Heat at Aperture Model H Old Type Film Speed— 80 ft. per min 565° 1486° O. F. S^ahr FIGURE 1—New 1002H Model Motiograph Film Speed — 90 ft. per min 570° Temperature Film Speed — 100 ft. per min 564° the same at Film Speed — 110 ft. per min 555° all speds. Average Temperature 564° "Thus, in the Model H Motiograph De Luxe the temperature at the aperture is 922° less than the old type projector, or 62^4 %. "Tests were taken in each case over a period of thirty minutes or more of operation of each projector with a reflecting arc type of lamp as illuminant operated at 25 amperes. "The heat at the point just between the cooling plate and gate door taken after thirty minutes operation to determine the comparative heating of the metal surrounding the aperture opening in gate door showed that with the Model H Motiodgraph De Luxe the temperature at this point remained constant at 100° as against a temperature of 270° on the old type projector. All temperature readings in degrees Fahrenheit. * * * "This actual comparison of heat of film temperatures at the aperture is really astonishing, and film runs cooler in the Model H even when the new highpowered illuminants are used, than it used to in the old projectors where the regular arc lamp and only 35 to 40 amperes at the arc were employed. "So evident is the result, that it is not necessary to have the testing engineer's report of aperture temperatures to prove it. Anyone may be convinced by an actual demonstration of the Model H Motiograph De Luxe against any proj.ector having the old type front shutter, by feeling the film in operation as it leaves the take-up sprocket. In the old type front shutter projector, the film will feel decidedly hot and it will be extremely uncomfortable to leave the fingers on the film for any length of time. In our Model H, the film will leave the lower feed sprocket practically as cool as when it was taken from the film can it was shipped from the exchange in. Moreover, the film will be absolutely flat, unwarped, buckled or embossed. "Its third purpose directly bears on the foregoing and benefits the entire industry in that