GB2084309A

GB2084309A - Automobile Headlamp with an Inclined Glass

Info

Publication number: GB2084309A
Application number: GB8129122A
Authority: GB
Original assignee: Cibie Projecteurs SA
Current assignee: Cibie Projecteurs SA
Priority date: 1981-09-25
Filing date: 1981-09-25
Publication date: 1982-04-07
Also published as: GB2084309B

Abstract

An automobile headlamp having an inclined glass, that is to say one whose front glass is not perpendicular to the longitudinal axis of the vehicle, comprises a housing 1 with an inclined aperture contour, an inclined glass 5 over the aperture contour, and a reflector 10 mounted in the housing 1, having its axis not parallel to the longitudinal axis of the vehicle but perpendicular to the aperture contour. The headlamp also has a deflector 20 inserted between the reflector 10 and the glass 5 in order to correct the deviation of the beam from the reflector due to the inclination of the axis of the reflector with reference to the longitudinal axis of the vehicle. <IMAGE>

Description

SPECIFICATION Automobile Headlamp with an Inclined Glass The present invention relates to automobile headlamps having an inclined glass, that is to say a glass the base plane or support plane of which (containing the glass contour and defining the aperture of the headlight) is not perpendicular to the longitudinal axis of the vehicle.

Such headlights conventionally comprise: a headlight housing which is open to the front, the aperture having a contour which is inclined, i.e.

not perpendicular to the axis of the vehicle; a reflector/bulb assembly mounted inside the housing; and an inclined front glass which closes the aperture and is integral with the housing or the reflector. The "housing" can be either a casing for the headlight, or a simple recess made in the bodywork of the automobile, in which the reflector and the bulb are installed. It should be understood that throughout this specification both possibilities should always be considered as covered.

The inclination of the front glass is generally intended to improve the aesthetic appearance of the vehicle and to perfect the aerodynamics whilst ensuring the continuity of the lines of the elements of the bodywork. However, it has always been considered that the axis of the reflector should of necessity be parallel to the longitudinal axis of the vehicle in order to direct the emitted beam in a general direction substantially parallel to this axis. Such an arrangement is described in French Patent Application No. 1518841 and in French Patent Application No. 2052239.

Patent Application No. 1 518841 describes headlamps for automobiles which have divergent shapes on either side of the vertical longitudinal median plane of the vehicle. The headlamps described are arranged on the bodywork in such a way that their respective axes are parallel to each other whilst being symmetrical with reference to the vertical longitudinal plane of the vehicle, and substantially horizontal. It is clearly specified and shown that the reflectors with which such headlamps are equipped much have their axes coaxial with the optical axis of the headlamp.

The inclination of the front glass of the headlamp coupled to such a reflector arrangement necessitates a relatively large overall depth of the housing.

In addition, it is necessary to provide a brace or intermediate part of asymmetric shape to ensure the connection between the reflector and the inclined front glass. It will of course be understood that the manufacture and insertion of such an intermediate part may raise the cost of manufacture of the headlamps and also tends substantially to increase the necessary overall depth of the housing.

For reasons of weight, of cost, and above all of available volume, automobile manufacturers would wish to reduce the bulk of such headlamps.

The immediate solution might be to reduce the external dimensions of the housing by reducing the depth of the reflector, but this modification would be prohibitive in that the quantity of luminous flex reflected by the reflector would be reduced at the same time. More generally, a problem to be solved is to reduce the bulk of the headlamp without reducing its optical performance or to improve its optical performance while maintaining the same dimensions.

Thus the present invention proposes a new structure for the headlamp which may solve the problem thus raised and which may be entirely satisfactory, although going against known ideas which insist that the axis of the reflectors must of necessity be co-axial with the optical axis of the headlamp, that is to say parallel to the longitudinal axis of the vehicle.

According to the invention, there is provided a headlamp for an automobile comprising a housing with an aperture contour which is inclined relative to a plane perpendicular to the axis of the vehicle, a similarily inclined glass over the aperture contour, a reflector mounted in the housing, the reflector having its axis not parallel to the longitudinal axis of the vehicle but in a substantially vertical plane and, perpendicular to the aperture contour, and a deflector means inserted between the reflector and the glass in order to correct at least partially the deviation of the beam from the reflector due to the inclination of the axis of the reflector with reference to the longitudinal axis of the vehicle.

According to a preferred embodiment, the deflector means consists of a transparent plate provided on its internal surface with moulded structures having the effect of prisms.

The glass can be for example a vertical glass arranged obliquely with reference to the longitudinal axis of the vehicle (corner glass), cooperating with a reflector having a horizontal axis oblique with reference to the longitudinal axis of the vehicle. It can also be such a corner glass which is slightly inclined (not vertical) and still cooperates with a reflector having a horizontal axis or an axis which is slightly inclined to the horizontal. It can also be a non-vertical glass, transverse to the longitudinal axis of the vehicle, co-operating with a reflector the axis of which is substantially normal to the plane of the glass.

The invention may be carried into practice in various ways and one embodiment will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is an axial section through conventional headlamp provided with a glass, the median plane of which is inclined with respect to a plane perpendicular to the longitudinal axis of the vehicle; Figure 2 is an axial section through a mounting in which the reflector is fixed so that its axis is normal to the median plane of the glass; Figure 3 is an axial section through a headlamp in accordance with the invention, and Figure 4 shows schematically the gain in depth of the housing obtained by inclining the reflector in accordance with the invention.

In all these drawings the same reference numerals designate the same elements.

According to the conventional embodiment shown in Figure 1, a reflector 10 is fixed inside a housing 1 in such a way that its axis is parallel to the longitudinal axis A of the vehicle, in order to orientate the beam of the headlight in a mean direction substantially parallel to the axis A. Such an arrangement necessitates a relatively large overall depth of the housing 1 because of the inclination of the median plane of the front glass 5.

On the other hand, it can be easily seen by reference to Figure 2 that an inclination of the axis of the reflector 10 with reference to the longitudinal axis of the vehicle, in order that its vertical axial plane should be normal to the base plane of the glass 5, results in a reduction of the overall depth of the housing 1.

The headlamp according to the invention as shown in Figure 3 is formed in this way. It comprises a housing 1 (a casing in the illustrated example) the forward inclined part of which constitutes an aperture provided with a glass 5, the base plane of which (the plane of the aperture contour) is inclined to a vertical plane passing through the longitudinal axis of the vehicle, by an angle preferably within the range from 100 to 200. A reflector 10 having a parabolic reflecting surface is mounted in the housing 1 by known means which are not shown.Associated with the reflector 10 is a bulb 12 which may be provided in a conventional manner with a direct light cover 1 The headlamp also has a deflector device 20 provided with prisms 21 or mounted structures having the effect of a prism, interposed between the glass 5 and the reflector 10, in order to bring the reflected rays B into a direction parallel to the axis of the vehicle. This deflector is preferably formed from a plate of plastics material.

In order to ensure a uniform correction of orientation of the beam it should be ensured that not too large a part of the incident beam strikes the relief surface of the prisms 21, since this part of the beam would then be deflected in a different direction, an effect which would be contrary to the result sought. For this purpose, the relief angle is practically zero, that is to say that the relief surface is formed in such a way as to be substantially perpendicular to the glass 20. Thus only a very small proportion of the incident beam will strike this relief surface. The pitch of the prisms 21 is determined in such a way as to maintain an acceptable extra thickness on the deflector 20.

According to the one possible desired configuration of the beam, it may be required to maintain a proportion of the rays travelling in their initial direction. In such a case the corresponding zone, for example in central axial zone, of the deflector plate will not be ribbed or grooved, but left smooth.

A numerical example of a construction of the headlamp according to Figure 3 will now be given: Angle of base plane of glass 5 with reference to the perpendicular to the longitudinal axis of the vehicle =150, Horizontal aperture of the reflector=220 mm, Vertical aperture of the reflector=1 10 mm, Focal length of the reflector=26.5 mm, Angle at the tip of the prisms of the deflector 20 made,from plastics material=270, Pitch of the prisms=5 mm, Extra thickness of the deflector 20=2.5 mm.

The overall depth of the housing according to this embodiment is equal in this example to 173 mm whereas according to the conventional construction of a headlamp having a parabolic mirror of the same characteristics and an external glass 5 the base plane of which has the same inclination of 150, the overall depth of the housing 1 would be 200 mm. The arrangement according to the invention thus permits a headlamp construction having the same characteristics as the conventional headlights but with a depth reduced by 27 mm.

According to a variation on this embodiment of the headlamp, it is also possible to arrange inside a housing 1 of conventional dimensions a mirror which is deeper than the mirror conventionally used, that is to say one of a smaller focal length.

Since the reflected flux varies in inverse proportion to the focal length, with an equal bulk of the housing 1 an appreciable gain in reflected flux would thus be obtained.

Thus, for example, by maintaining an overall depth of housing of 200 mm, it is possible according to the invention to replace a parabolic mirror with a focal length of 23 mm by a parabolic mirror with a focal length of 26.5 mm, which makes it possible to obtain a gain in flux of the order of 25%.

It should be noted that the invention may provide specifically: oblique vertical glasses (corner glasses) co-operating with reflectors whose axes are vertical and perpendicular to their respective glasses; non-vertical glasses cooperating with reflectors having their axes horizontal but situated in vertical planes perpendicular to the base plane of their respective glasses; or non-vertical glasses transverse to the longitudinal axis of the vehicle and co-operating with reflectors having their axes not horizontal, but situated in vertical planes perpendicular to the base plane of their respective glasses, the vertical planes thus being substantially parallel to the longitudinal axis of the vehicle.

In general, the invention is not limited to the examples of embodiments described above and illustrated but may apply to all inclinations of the glass to the vertical and/or to the horizontal.

The invention may also apply in cases where the axis of the reflector is moved away from the longitudinal direction of the vehicle in order to bring it closer to the normal at an inclined aperture contour (for example turned towards the left or the right), such distancing being compensated for at least in part by a deflector.

Such movement towards the normal, even limited, may always result in an appreciable redirection in bulk.

Claims

1. A headlamp for an automobile comprising a housing with an aperture contour which is inclined relative to a plane perpendicular to the axis of the vehicle to a plane perpendicular to the axis of the vehicle, a similarly inclined glass over the aperture contour, a reflector mounted in the housing, the reflector having its axis not parallel to the longitudinal axis of the vehicle but in a substantially vertical plane and perpendicular to the aperture contour, and a deflector means inserted between the reflector and the glass in order to correct at least partially the deviation of the beam from the reflector due to the inclination of the axis of the reflector with reference to the longitudinal axis of the vehicle.

2. A headlamp as claimed in Claim 1 in which the deflector means is constituted by a transparent plate provided with moulded structures having the effect of prisms.

3. A headlamp as claimed in Claim 1 or Claim 2 in which the glass is vertical and arranged obliquely with reference to the longitudinal axis of the vehicle and the axis of the reflector is horizontal and oblique with reference to the longitudinal axis of the vehicle.

4. A headlamp as claimed in Claim 1 or Claim 2 in which the glass is a non-vertical corner glass and in which the axis of the reflector 10 is horizontal.

5. A headlamp as claimed in Claim 1 or Claim 2 in which the glass is a non-vertical corner glass and in which the axis of the reflector is not horizontal, but substantially normal to the base plane of the glass.

6. A headlamp as claimed in Claim 1 or Claim 2 in which the glass is not vertical but is transverse to the longitudinal axis of the vehicle and in which the axis of the reflector is not horizontal but substantially normal to the base plane of the glass.

7. A headlamp as claimed in any of Claims 1 to 6 in which the deflector includes a smooth portion at its central axial zone.

8. A headlamp for an automobile constructed and arranged substantially as herein specifically described with reference to and as shown in Figure 3 of the accompanying drawings.