Education and demonstration – Vehicle operator instruction or testing
Patent
1997-02-13
1999-02-23
Smith, Jeffrey A.
Education and demonstration
Vehicle operator instruction or testing
434 38, G09B 902
Patent
active
058737260
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the generation of an image, for example in a flight simulator or other arrangement in which an artificial panorama is to be viewed.
When the eye receives light from an object, the angle of divergence of the light from the object to the eye depends on the distance therebetween. Distant objects will have parallel, or virtually parallel light rays therefrom, whilst light from near objects will diverge significantly at the eye. Therefore, if an image of a panorama is generated on a display such as a monitor or a projection onto a screen for use in a flight simulator, the person using that simulator will be able to judge the distance to the monitor on the basis of the light divergence and thus will not be presented with a realistic panorama.
Therefore, simulators have been produced in which light from a display is incident on the concave surface of a spherical mirror, since that mirror then collimates the light into parallel rays, thereby giving the impression that the light from the spherical mirror has its origin at infinity. The person using the simulator thereby is given the impression of a realistic panorama of distant objects, rather than perceiving the image generated by the display as being close.
However, spherical mirrors are difficult and expensive to produce, due to the high levels of optical accuracy needed, and therefore the present invention seeks an alternative.
At its most general, the present invention proposes that two mirrors are used, each of which is singly curved. This means that the surface of each mirror is curved but any point on the surface has a tangent plane which meets the surface at a line. This is to be contrasted with spherical or other compound curved surfaces in which tangent planes always meet the surface at a point. The two mirrors are positioned so that light from a display passes from one mirror to the other, and thence to the eye of an observer.
Such singly curved mirrors may be formed by bending a plane flexible sheet using bending moments and forces applied to or adjacent two opposite edges only. The sheet can thus be bent by mounting it in a frame that exerts bending moments and forces close to its edges, to give it its singly curved shape. The sheet may be provided with a reflective layer either before or after bending.
The optical effect thus achieved will permit collimation of a light beam which has been reflected from the concave surfaces of the mirrors.
Therefore, the present invention may provide a simulator having an image-generating display from which light passes to the first singly curved mirror, from that mirror to the second singly curved mirror, and from that mirror to the eye of the person using the simulator. Additional optical components (such as plane mirrors) may be provided in the optical path between the display and the eye, but this is undesirable as each reflection is not perfect and therefore reduces the amount of light being received. Therefore, the simplest arrangement is for two cylindrical mirrors to be immediately adjacent, and the cylindrical mirror which is closest along the optical path to the display be semi-reflective only, so that the second mirror is viewed through the first mirror.
Preferably the mirror system is symmetric about the plane containing the viewing point of the user and the normal to the centre of the display.
In such an arrangement, there is preferably a plane in which the mirror is curved and perpendicular to which the mirror is straight; i.e. the mirror has a direction of translational symmetry. The directions of translational symmetry of the two mirrors are then preferably mutually perpendicular.
It should be noted that, since the aim of the present invention is to present the image from the display as if it originates at a remote distance, the term "collimated" should be interpreted as including the case where the light diverges by only a small amount, or is collimated less in one axis than another, such as when the image is to be effectively at the horizon, rather than necessarily a
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Patent Abstracts of Japan, vol. 018 No. 241 (P-1733), May 1994.
Patent Abstracts of Japan, vol. 014 No. 452 (P-1112), Sep. 1990.
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