Film constraint and illumination system
AssigneeEastman Kodak Company
InventorRobert C. Bryant
Life of this patent
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Abstract
A rigid transparent cylinder is rotated about its axis of symmetry at a relatively high rate of speed by means of a motor. Around a portion of the circumference of the rotating cylinder is wrapped a flexible imaging medium such as photographic film, to which is applied longitudinal tension through means of a film transport. The film conforms to the curvature of the drum, but is held a small distance above the surface of the cylinder in equilibrium between the aerodynamic forces created by the rotating cylinder and the applied tension of the film transport, thus effecting a compliant surface air bearing. A stationary lamp within or behind the transparent cylinder passes light through the cylinder to project an image from the film onto a scanning element by use of a conventional optical system.
Claims15
A film gate for projecting by optical means onto a linear array, at least a portion of the selected image recorded on the film, said gate comprising:
- a film transport for transporting said film longitudinally in either direction while maintaining a predetermined tension in said film;
- means for controlling said film transport to accurately position the desired portion of the film in the gate;
- a translucent cylinder aligned with its major axis perpendicular to the longitudinal movement of said film;
- drive means for rotating said cylinder about its axis;
- illumination means for illuminating said interior of said cylinder;
- inlet and outlet constant means located adjacent said cylinder so as to define a path for said film around a portion of the perphery of said cylinder when it is held a small distance above the surface of the cylinder by a balance of aerodynamic forces developed by the rotating cylinder and the applied tension of the film transport.
A method for supporting film in a film gate on a compliant fluid medium comprising the following steps:
- rotating a translucent cylinder about its major axis to create an aerodynamic lifting force near the surface of said cylinder;
- applying a predetermined longitudinal tension to the film;
- and
- partially wrapping film about a portion of the circumference of said cylinder such that the film is held a small distance above the surface of the cylinder by a balance between the aerodynamic lifting force developed by the rotating cylinder and the tension applied to the film.
Dependencies are inferred from the claim text.