GB2123133A - Truncated motor vehicle headlamp - Google Patents

Description

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GB 2 123133 A

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SPECIFICATION

Truncated motor vehicle headlamp

5 Theinvention is in the field of lamps for automobiles and other vehicles, such as headlamps and fog lamps, having truncated reflectors, i.e., reflectors having a concave surface which is truncated at the top and/or bottom.

10 Certain headlamp reflectors aretruncatedattheir top and/or bottom to reduce theirvertical heightfor betterfitting and styling in automobiles. In these and othertypes of headlamps, a shield or other means is used to achieve sharp beam cutoff to reduce glare 15 above the horizontal, specifically in low-beam lamps usedforcitydriving. U.S. Patents 1,359,789to Brown and 4,276,583 to Fratty disclose truncated headlamps, in which Brown employs an auxiliary reflector and Fratty employs a shield to reduce glare. Attempts to 20 design truncated headlamps having reduced glare, withoutthe use of internal shields, have not been completely successful, especially where the filament is enclosed in a glass inner bulb.

The invention attempts to provide an improved and 25 economical truncated vehicle lamp of compact size, withoutshieldingthefilament from the reflector, and which projects a light beam, when installed on a vehicle, that is substantially entirely below the horizontal thereby significantly reducing glare. 30 The invention comprises, briefly and in a preferred embodiment, a vehicle lamp having a generally parabolicorconcave reflectorwhich istruncated at its top, bottom or sides, thus providing one or more flat sections substantially parallel to the reflector's optical 35 axis. The optical axis does not coincide with the center of the reflector. Furthermore, theflat surfaces are non-reflective, such as by being transparent or light-absorbing. This construction achieves the desired improvement in glare reduction and eliminates the 40 needforpriorartfilamentshield.

The present invention will be further described, by way of example only, with reference to the accompanying drawings, in which:—

FIG. 1 is a front view of a headlamp in accordance 45 with a preferred embodment of the invention.

FIG. 2 is a side sectional view taken on the line 2-2 of FIG. 1.

FIG. 3 is a horizontal sectional view taken on the line 3-3 of FIG. 1.

50 The headlamp comprises a reflector 11 having a generally parabolic or other concave reflecting surface 12 which may be a true parabola or a modified parabola configuration having an optical axis 13. A light bulb 14, preferably a halogen type, is held in the 55 reflector11 by conventional orothersuitable means, and contains a filament 16 or other suitable light source at or nearthe optical axis 13andalso atornear thefocal point of the reflector 12 so that the reflector 12 will reflect light from the light source 16 in a desired 60 forward pattern as exemplified by the reflected light ray 17. If desired, the fronttop half of the bulb 14may be rendered opaque, such as with a coating 18 of dark material, to block light rays that would emanate directly through the lens at an upward angle above the 65 horizontal optical axis 13.

Thetop and bottom parts of the reflector 11 are truncated to form substantially flattop and bottom sections 21,22 which may both be parallel to the optical axis 13. A transparent cover plate or lens can be attached overthefront opening of the reflector in conventional manner. One of the flat sections, such as thetop section 21, is considerably closerto the optical axis 13 than is the other flat section 22, whereby the reflecting surface 12 is approximately a half-section, or slightly wider, of the more conventional symmetrical parabolic reflector. This provides more accurate beam design control of the reflected beam pattern and achieves substantial reduction of undesirable glare light above horizontal by eliminating the conventional parabolic upper half reflecting surface which, if present, would cause some glare light having an upward directional component. The light source 16 should be frontwardly of the junction lines 21' and 22' of the flat sections 21,22 and the parabolic section 12, at least in the vicinity 22" of the vertical plane in which the light source lies, to prevent glare rays caused by light reflected from innersurface areas of the bulb, frontwardly of the light source, and reflected by the parabolic reflector surface.

In accordance with the invention, one or both of thetop and bottom reflector sections 21,22 are made so as to be substantially non-reflective of light. This can be accomplished by making them transparent, or of a light-absorbing material, orcoating them, preferably at their inner surfaces 23,24, with a dark non-reflective material such as paint. The terms "non-reflective" and "substantially non-reflective" as used herein mean that a surface has a low reflectivity so as to reduce glare in accordance with the invention, it being recognized that it is difficult or impossible to achieve absolutely zero reflectivity at a surface.

As has been described, the parabolic reflecting surface 12 reflects light rays from the light source 16 in a desired frontwardly direction, and, if desired, can be contoured to reflect some light downwardly and frontwardly to illuminate the road nearthe vehicle, none of this reflected light having a deliberate upward componentwhich can cause glare for oncoming motorists. Also, some light from the light source 16 will project directly frontwardly and downwardly through thefront of the headlamp adding to the nearby road illumination but not causing glare. As has been stated, the opaque coating 18 on the front of the bulb blocks and prevents direct glare light rays. Some light rays 26 from the source 16 are at an upward and rearward angle, and are not reflected by the non-reflective surface 23 because it is absorbed by its dark color or because it passes through a transparent truncated section 21 and becomes trapped or absorbed by the vehicle hood or otherstructural members. If, however, the rays 26 were reflected at surface 23, they would follow a path 27, be re-reflected by surface 12 into a path 28, and again be re-reflected by surface 24 (if reflective) into a path 29 frontwardly and upwardly from the headlampthus causing undesired glare to oncoming motorists. There would bean infinite number of such undesired glare rays, reflecting at diverging angles, i.e., "fanning out" and scattering from the surfaces 23 and 24 and causing a wide-spreading projected beam ofKght bavingan

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GB2 123 133 A

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undesirable upward glare component. Also, light rays reaching the front region of the lower surface 24 directly from the source 16 would, if this surface were reflective, be reflected with a glare-producing upward 5 component. The invention, by providing non-reflec-tive characteristics atthe truncated sections 21,22, prevents orsubstantially reduces the glare light. Numeral 31 indicates a light ray reflected by the inner surface of the bulb 14 in an upward and rearward 10 direction similarto the just-described ray 26, and which is not reflected by the truncated areas 21 and 22; if these areas were reflective, the ray 31 and others generally in thesame direction would be multiply reflected and emerge as glare rays similarto ray 29. 15 The sides 32,33 of the reflector can be truncated, if desired, to reduce the horizontal width, and may be either reflective or non-reflective because sideways (but not upward) reflected rays are relatively unimportant. Also, the light bulb 14, although shown horizon-20 tal, can be vertical or at another angle. With suitable redesign, the headlamp can be turned over so that area 22 is the top and area 21 is the bottom, the opaque coating area 18, if provided, being relocated on the bulb to block direct frontward light rays that 25 would have an upward component through the front of the headlamp.

While preferred embodiments and modifications of the invention have been shown and described,

various other embodiments and modifications thereof 30 will become apparent to persons skilled in the art and will fall within the scope of the invention as defined in thefollowing claims.

Claims (4)

1. A vehicle lamp comprising a concave reflector 35 truncated at opposite sides thereof to provide two generally flat sections substantially parallel to each other and to the optical axis of a curved portion of the reflector, and a light source contained within said reflector, one of said generally flat sections being 40 substantially closerthan is the otherto said optical axis, said lamp being devoid of any shield between said light source and said curved portion of the reflector.

2. A lamp as claimed in claim 1, in which said light 45 source is positioned substantially on said optical axis and frontwardly of the junctions of said generally flat truncated sections with the reflecting section of the reflector, at least in the vicinity of the vertical plane in which the light sou rce lies.

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3. A lamp as claimed in claim 1 or 2, in which both of said generally flat sections are substantially non-reflective of light generated by said light source.

4. A lamp as claimed in claim 1, substantially as hereinbefore described in the accompanying draw-55 ings.

Printedfor Her Majesty's Stationery Office byTheTweeddale Press Ltd., Berwick-upon-Tweed, 1984.

Published atthe Patent Office, 25 Southampton Buildings, London WC2A1 AY, from which copies may be obtained.