Optical: systems and elements – Mirror – Plural mirrors or reflecting surfaces
Patent
1994-04-29
1996-06-11
Dzierzynski, Paul M.
Optical: systems and elements
Mirror
Plural mirrors or reflecting surfaces
359854, 359857, 359837, 359731, 359737, 359851, 359863, G02B 508, G02B 510, G02B 1700, G02B 300
Patent
active
055261957
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention concerns improvements in or relating to rear view systems for vehicles and vehicles incorporating such systems.
In particular, although not exclusively, the present invention has reference to such a system suitable for use on motorised road vehicles.
2. Description of Related Art
Conventionally, a motorized road vehicle is provided with an internally mounted rear view mirror to give the driver a central vision through the rear window, and either wing or door mounted mirrors to give marginal vision to the rear and, in a narrow path, adjacent the side of the vehicle. For reasons of safety, it is desirable to afford the driver of the vehicle with as comprehensive as possible a view of the prevailing ambient driving conditions. It is known therefore to enhance the vision through the rear window by making the mirror convex to provide a panoramic view, but clearly the degree to which such can be achieved depends upon the vehicle body configuration and invariably the view is impaired by opaque parts of the body structure. Additionally, or in the alternative, it has been proposed to locate a prismatic lens at the rear of a vehicle, more especially a commercial vehicle, such that images of objects immediately to the rear of the vehicle are transmitted to the driver through the agency of a mirror. Similarly, endeavours have been made to improve the vision given by side mirrors, for example by adding a small convex mirror section in one corner in an attempt to give a wider viewing spectrum. However, the image is inevitably small which necessarily militates against the alleged advantage of providing a vision of greater breadth.
It is further known to provide side mirrors combined in close juxtaposition with prismatic arrangements for refracting light rays from objects to the rear of the vehicle, but the images of the mirrors necessitate diversion of the driver's eyes from the path ahead, and in any event tend not to widen the viewing scope.
SUMMARY OF INVENTION
It is an object of the present invention to provide a rear view system for a vehicle having the capacity of facilitating inspection of the rear vista and for capturing a wider field of view than possible with conventional or known systems.
It is a further object of the invention to provide a vehicle incorporating such a rear view system.
According to a first aspect of the invention a rear view system for a vehicle includes in combination a light transmitting member and a light reflective medium spatially displaced from the member, the member presenting a first face for light emergence from which in use light rays are directed towards the medium and a second face for light incidence, each face being disposed on a respective side of a median plate, the member comprising a plurality of elemental prismatic sections, the prismatic angles of the elemental sections progressively changing along the length of the member whereby rays of refracted light emerging through the first face are in parallelism or substantial parallelism one with the other irrespective of the angles of incidence of the rays.
Advantageously, the member is so designed to ensure that the incident rays undergo essentially minimum deviation through the prismatic elemental sections.
Conveniently the shape of the first face of the member is generated by a locus of points calculated by the following formulae wherein the `y` axis is aligned along the median plane and the `x` axis extends orthogonally thereto: /2)+x.sub.n-1 ( 1) /2)+y.sub.n-1 ( 2)
Similarly the shape of the second face of the member is generated by a locus of points calculated by the following formulae wherein the `y` axis is aligned along the median plane and the `x` axis extends orthogonally thereto: -d.sub.n-1)/2}.multidot.W.sub.n-1 ]/cos (A.sub.n /2)+x.sub.n( 3) -d.sub.n-1)/2}.multidot.W.sub.n-1 ]/cos (A.sub.n /2)+y.sub.n( 4)
In the above formulae, the symbols used except where indicated otherwise have the following meanings or values: ##EQU1##
In practice the member
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patent: 3179797 (1965-04-01), Franck
patent: 3864025 (1975-02-01), Picardat
patent: 3972596 (1976-08-01), Baumgardner et al.
patent: 4274714 (1981-06-01), Okamura
patent: 4986631 (1991-01-01), Aoki et al.
patent: 5002375 (1991-03-01), Komplin et al.
Dzierzynski Paul M.
Optical Perspectives Ltd.
Sikd-er Mohammad Y.
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