The Exhibitor (1960)

The Philips Multi-Purpose Projector Construction Details Of The Completely New Machine Developed For 70/35mm Films ■ Philips Multi-Purpose 70/35mm film projector (originally developed for the ToddAO System) is a machine capable of project¬ ing films made in any of the motion picture systems available for normal distribution to¬ day. It offers all facilities for Large Picture Pro¬ jection and Multiple Track Magnetic Sound Reproduction. The projector is suitable for: 70 or 65mm film provided with up to six magnetic sound tracks; CinemaScope film provided with four magnetic sound tracks; CinemaScope film with optical sound track or Perspecta-Sound; CinemaScope Magoptical prints: Wide Screen film of any aspect ratio provided with mag¬ netic or optical sound tracks, and Standard 35mm films. Its versatility is such that changing from one projection system to another (i.e. from 70mm to 35mm systems and vice versa) takes only a few minutes. Driving Mechanism The driving mechanism is very sturdy and at the same time very simple, making it per¬ fectly reliable. The sprockets, the intermit¬ tent mechanism, the shutter and the take-up spool are driven by a stout vertical main spindle. This spindle is driven by a horizontal shaft, which also drives the spur-gear oil pump located in the base of the projector housing and hence is always below the oil level. All the gear-wheel transmissions and bearings are richly lubricated via an oil conduit with tappings. Philips Multi-Purpose 70/35mm Projector By W. J. M. .Jansen Ph il I ps, Li rn i t vd Intermittent Mechanism In principle, the intermittent mechanism of the projector equals that of normal 35mm mechanisms, but it is of much more robust construction. However, to keep the accelera¬ tion forces and therefore wear of the mech¬ anism as low as possible, it is of the utmost importance that the Maltese cross and the intermittent sprocket be light. Aluminum was the most obvious material to use, since it is light in weight, but it is also soft and therefore at first sight did not seem suitable for the manufacture of sprock¬ ets. After many experiments, a special meth¬ od was found for hardening the surface of the aluminum, and a life test proved that aluminum sprockets treated in this way com¬ pared very well with chrome -nickel sprock¬ ets. Picture Gate The larger size of the image area also en¬ tails a different construction of the picture gate. Due to the greater mass of the 70mm film, the normal construction (a flat runner plate and resilient pressure skates) provides inadequate braking power. For good defini¬ tion it is furthermore necessary that the dis¬ tance between the film in the gate and the projection lens should not vary. When a flat gate is used, 70mm film is liable to bend in a transverse direction and this cannot be re¬ medied. For these reasons, the projector is equipped with a curved runner plate. The slight bend in a longitudinal direction gives the film a greater transversal stiffness. Shutter The Philips projector is equipped with a one-Blade conical shutter with a very large diameter. At a film speed of 30 frames/sec the shutter rotates at a speed of 3600 r. p. m. and at a film speed of 24 frames /sec at 2800 r. p. m. This type of shutter has been chosen for the following reasons: The ToddAO system is intended in the first place for the projection of very large pictures. Loss of light must therefore be avoided as much as possible. The conical shutter can be mounted close behind the mask, so that it intercepts the light beam where it is narrowest. This, in conjunction with the large diameter and the high speed, guarantees the smallest possible angle of interception and the highest efficiency for this type of projector. Cooling The high light-intensity and the great heat it generates require powerful and efficient cool¬ ing of both the film and the projector. For this reason, the plate on which the pressure The Philips Multi-Purpose 70/35mm projector is marketed in the U.S.A. by: NORELCO, North American Philips Company, Inc., Motion Picture Equip¬ ment Division, 100 East 42nd Street, New York City 17. strips are mounted is watercooled. The shutter of the projector has been constructed as a powerful fan which sucks in the cold air from the rear of the projector and blows it against the film in the gate. Lens Holder The Todd-AO system requires a very large optical system. The size of this system deter View of Projector with Rear Cover Removed mines that of the lens holder. The lens is focused by means of the knob underneath the lens mount bracket over which the entire lens holder slides during focusing; this adjustment is free of any backlash. Projector Head with Door Removed to Give View of Film Path , 46 MOTION PICTURE EXHIBITOR-1960 THEATRE CATALOG Edition April 6, 1960