Imax Systems Corporation

Imax Entertainment Limited

William C Shaw

Ian Maxwell

Gordon W Harris

Marian Toporkiewicz

Irvine W Smith

A projector having a rolling loop film transport mechanism is provided with a film decelerating cam unit that is located in advance of the aperture of the projector. Deceleration pins carried by a pair of vertically spaced arms that project from the cam unit engage in upper and lower marginal perforations in the film and travel with the film towards the aperture and decelerate the film as each frame is advanced. The cam unit includes two cams, one of which causes the decelerating motion of the pins, and a return motion in the reverse direction, while the other cam causes the pins to advance and retract into and from the film path respectively. By positively retracting the pins, their return movement against the direction of film travel can take place independent of the motion of the film. As compared with the prior art, acceleration forces and resultant stresses on the cam are reduced and the cam unit can operate at higher frame rates and/or with smaller rotor gaps.

Film deceleration unit

Projected image misalignment in a 3-D motion picture projector is corrected by shifting one of the projection lenses in accordance with a predetermined program during presentation of the motion picture. In one embodiment, manually initiated control signals for adjusting the lens shift are recorded in a memory and can be subsequently retrieved for automatically controlling lens shift. In another embodiment, lens shift is controlled by reading predetermined witness marks on the film.

Projected image alignment method and apparatus

A camera for producing 3-D motion pictures has 'left eye' and 'right eye' camera lenses and two corresponding film transport mechanisms. Images to be recorded on films transported by the mechanisms are reflected by semitransparent mirrors and the mechanisms and the mechanisms are arranged so that the mirrors turn the images transversely of the films. Contact prints made from the films can then simply be turned face-for-face to correct for the image reversals due to the presence of the mirrors. The contact prints are then correctly oriented for projection.

Camera and method of producing and displaying a 3-D motion picture

In an alternate eye 3-D motion picture projection apparatus of the rolling loop type, light projection is accomplished by the combination of focal plane shutters that are coupled to the rotor of the projector and a supplementary shutter arrranged to trim the projected light so that discrete 'left eye' and 'right eye' images are projected. Various embodiments are disclosed in which a rotary blade shutter is located at the stop of the projection lens. Where there are two projection lenses, a single blade or two counter-rotating blades trim the light projected through both lenses.

3-D motion picture projection apparatus

A method of producing and displaying a 3-D motion picture is disclosed. Two master film negatives are prepared using a camera rig employing one camera that looks directly at the subject through a semi-transparent mirror and a second camera that looks at the same subject by way of the reflective surface of the mirror, to obtain left and right eye images. The cameras are oriented so that the mirror images recorded by the second camera are turned laterally of the film in being reflected by the mirror. Contact prints are made from the negatives. Before projecting the images, the contact print from the negative that was shot by way of the mirror is turned about its longitudinal axis so that images on that print are turned laterally. Images from the two prints are simultaneously projected onto the same screen to produce a coincident 3-D image. The left and right eye images are optically coded, for example by using optical filters that are polarized at right angles to one another. The viewer wears spectacles having corresponding polarized lenses so that the left eye sees only projected left eye images while the right eye sees only projected right eye images.

Method of producing and displaying a 3-D motion picture

A film support element assembly is disclosed, primarily for supporting film in relation to a projection aperture in a motion picture projector having a rolling loop film transport mechanism. In a preferred embodiment the film support element is a so-called 'field flattener' and has a cylindrically curved surface over which successive frames in the film are laid by the mechanism. Cleaning means are provided adjacent the film path and the lens element can be displaced to bring a fresh portion of the surface into the film path. At the same time, the cleaning means remove debris from the surface. In one embodiment the lens element is vibrated to discourage adhesion of debris.

Film support element assembly

A projection screen assembly is disclosed. The assembly includes a screen which can be lifted into an extended position or lowered into a collapsed configuration for permitting a building in which the screen is installed to be used for other purposes. Lifting means is provided for raising the screen and tensioning it in the vertical direction. Lateral tensioning is effected simultaneously by tensioning elements disposed one adjacent each side edge of the screen. The tensioning elements are coupled to the screen by lateral tensioning members which are of progressively decreasing length in directions extending inwardly from the upper and lower margins of the screen so that the tensioning elements adopt the shape of caternary curves. When the screen is tensioned vertically, these curves are flattened so that the screen is tensioned laterally by the lateral tensioning members.

Projection screen assembly

A film support element assembly is disclosed, primarily for supporting film in relation to a projection aperture in a motion picture projector having a rolling loop film transport mechanism. In a preferred embodiment the film support element is a so-called 'field flattener' and has a cylindrically curved surface over which successive frames in the film are laid by the mechanism. Wiper elements are provided above and below the film path and the lens element can be displaced to bring a fresh portion of the surface into the film path. At the same time, the wiper elements remove debris from the surface. The wiper elements are removable for disposal of collected debris.

Field flattener lens element assembly

Inlet guide structure is provided having complementary outer and inner guides which are adapted to receive film from a drive sprocket of a rolling loop film transport mechanism and to guide the film inwardly towards a path defined between the stator and the rotor of such a mechanism. The outer and inner guides have respective pairs of co-operating side faces for guiding side portions of the film remote from a centre portion of the film. The side faces of the outer guide define a rounded nose portion intermediate ends of these side faces, and the side faces of the inner guide define a depression corresponding to the nose portion so that when in use the guides combine to form a passage which guides the film by contact between the side faces and the side portions of the film. The nose portion and depression combine to cause the passing film to define a transverse curve about the nose portion, and the passage restrains the film to leave the passage at an acute angle to said path between the stator and the rotor so that an impact by the rotor will start a loop to grow and any tendency for creation of a rigidifying longitudinal bend will be significantly limited because the film is rigidified transversely by the transverse curve about said nose portion.

Growing community of inventors

Streetsville, Canada

William C Shaw