Patent GB-1280461-A (GB)
Title: Improved method and apparatus for producing a projected visual scene
Inventor: CUTLER ALBERT ERNEST
IPC: G09B9/32
Filed: 1968-07-19
Abstract: 1280461 Aircraft flight simulators REDIFON Ltd 16 July 1969 [19 July 1968] 34519/68 Heading B7W A visual display system simulating the view of a ground surface, for example in an aircraft flight simulator, comprises: a camera optical system having a lens C, Fig. 1, wherein a first image F 1-4  of the ground G 1-4  is formed on a first image plane in the camera, which plane is inclined to the ground; a recorded image derived from the first image (e.g. 1a photographic film is processed) and placed in a second projector image plane LR inclined to the ground; a projector which projects from the second image phase a viewed image D 1-4  through a lens P onto a screen 12 in a plane LS inclined to the ground; the relative inclination of the ground and the planes LR, LS, being such that they intersect along a common line L, whereby an observer O, fixed relative to the screen 12, views the viewed image D 1-4  in correct perspective (as indicated by the lines ODG) when the first and second planes are coincident. The scales of the first image and recorded image may be changed, the changes being compensated by proportionally changing the position of the lens P of the projector, Figs 3a, b (not shown). The screen may be moved to a position parallel to the position shown in Fig. 1, with corresponding repositioning of the observer to retain correct perspective, Fig. 4 (not shown). In practice a cine film (i.e. a series of recorded images) is shot of a view from an aircraft following an ideal flight path or a nearly ideal flight path in which case compensation is made during processing to produce a cine film of an ideal flight path, which cine film is then projected in a simulator. The lenses P, C are tilted with respect to the various planes to focus the respective images. In order to change the viewed image to give simulated views of simulated deviations horizontally and vertically from the ideal flight path, the projector is moved respectively horizontally or vertically with respect to the plane LR. The projector 23, Fig. 13, having a lens 28 is moved vertically on screws 60, 61 by a motor 40, the screws and motor being mounted on blocks 63, 64. The blocks 63, 64 are moved horizontally with the projector on screws 65, 66 by a motor 39. In order to preserve focus and correct perspective the film carriage is moved relative to the lens of the projector an amount proportional to the movement of the projector as the lens is tilted in response to vertical movement of the projector. A mount 80 for the film carriage is thus moved vertically by screws 82, 83 and horizontally by screws 93, 93, the screws 82, 83 being driven by the screws 60, 61 via gearing 74, 75, 85-88, 88<SP>1</SP>, the pinion 75 being fixed to the shaft 85, and the screws 93, 94 being driven, by the screws 65, 66 via gearing 72, 72<SP>1</SP>, 73, 95, 96, 97. The motors 39, 40 are controlled by a computor which also controls film projection speed to simulate flight speed and motion of a simulated cockpit to simulate pitching and heaving.