GB2219386A

GB2219386A - Light deflecting patch

Info

Publication number: GB2219386A
Application number: GB8912214A
Authority: GB
Inventors: John Edward Starmer
Original assignee: METRO PRODUCTS
Current assignee: METRO PRODUCTS
Priority date: 1988-06-01
Filing date: 1989-05-26
Publication date: 1989-12-06
Anticipated expiration: 2009-05-26
Also published as: GB8912214D0; GB8812950D0; GB2219386B

Abstract

A light-deflecting patch for a motor vehicle headlamp comprises a transparent optically deflecting material shaped to cover the portion of the headlamp surface through which the dipped beam is projected. The patch deflects the whole of the diced beam from one side of the road to the other, thereby converting the vehicle for use in a country which drives on the opposite side of the road from its country of origin. <IMAGE>

Description

LIGHT DEFLECTING PATCH This invention relates to a light-deflecting patch for a motor vehicle headlamp. It is particularly concerned with adaptation of vehicle headlamps installed for use in a country which drives on a given side of the road so as to allow the vehicle to be used in countries which drive on the other side of the road. The requirement for the adaptation is to deflect the dipped headlamp beam in a lateral direction so that it projects towards the kerbside rather than towards the centre of the road or into the eyes of oncoming motorists.

The greatest volume of cross border traffic requiring such adaptation occurs between the British Isles and Continental Europe. As viewed from the driver's seat, the British (right hand drive) cars require dipped beam deflection to the right; Continental (left hand drive) cars to the left.

Several prior proposals have been made for adjusting the projected beam of a vehicle headlamp for such a purpose.

UK patent 1 085 251 discloses a transparent attachment, detachably mounted to the headlamp body and incorporating parallel prismatic ribs to cause the deflection. Its disclosed means of attaching and detaching is a plurality of resilient straps and the attachment extends over the whole frontal area of the headlamp. UK patent 1 378 162 describes and claims a similar attachment, which it defines as an auxiliary lamp lens member, in which the means of attaching and detaching is a combination of a plurality of resilient clips carried by the lens element and adapted to engage resiliently respective portions of a vehicle lamp.

Such attachments and elements were a commercial success and were widely used on vehicles ferried across the English Channel.

During the lifetime of these patents there were however a number of developments in headlamp design, partly in order to improve light output and partly to give a headlamp configuration to match and enhance the streamlined shape of the vehicle body. The large range of headlamp sizes and shapes that resulted from these developments would have demanded an equally large range of attachments in order to provide a version to fit each type of vehicle. The level of stock of such different attachments which motor component suppliers would have needed to maintain was one of various factors that caused the use of the attachments to decline.

A different solution to the problem is described in UK patent 1 462 044 which instead of a transparent attachment uses a piece of opaque sheet cut by the vehicle user to a generally trapezoidal form along marked lines on the surface of the sheet which delineate the shape suitable for his particular vehicle. The cut-out sheet is adhesive-backed for attachment to a correspondingly marked portion of the headlamps front glass surface. The effect of attaching the opaque sheet is to blank out the portion of the dipped beam that would be directed to the other side of the road. This system is easily adapted to different sizes and shapes of headlamp and has been widely used. It does however have a number of disadvantages.Thus when the adhered sheet is to be removed from the lamp on return to the home country it not only tends to tear but is also only reusable for a subsequent trip by further application of an adhesive material. The delineation of the trapezoidal shapes on the uncut sheet needs to be regularly updated as new versions of headlamp are introduced so that the user is able to cut out a shape which ensures that the offending portion of the beam is reliably blocked.

The most serious disadvantage of such blocking systems arises however from the beam pattern of modern vehicle headlamps. In these the full beam is projected forward through a major proportion of the glass frontal area of the lamp, with the main projection being through a central band in the upper half. In contrast, almost all of the dipped beam is projected through a small zone slightly to one side of the centre of the frontal area. It is this small zone which the opaque patch of the prior proposal is required to block. The face of the opaque patch in contact with the outer glass surface of the headlamp has a reflective surface whereby the dipped beam is reflected back into the lamp interior to be further reflected by the lamp's reflecting surface. Light from the dipped beam is thus repeatedly reflected until it leaves the lamp through an unblocked portion of the front glass surface.The repeated reflections and passage through the glass not only result in a loss of light output but also give a diffuse spread of light, lacking the desirable intensity for a dipped beam.

The present invention is also concerned with preventing the projection of an offending headlamp beam. According to the invention this is however achieved not by an opaque patch but by a transparent patch with optical deflecting properties.

According to the invention there is therefore provided a light-deflecting patch for a dipped beam from a vehicle headlamp which patch comprises a transparent optically deflecting material shaped to cover the portion of the headlamp surface through which the dipped beam is projected.

For convenience of reference herein the elements of the patch are described in terms of their intended position on the vehicle headlamp.

Suitable optically deflecting materials for the patch include glass and transparent plastics, for example polyvinyl chloride (pvc), polycarbonate, polyacrylates and polystyrene.

The optically deflecting properties are preferably imparted to the material by a grooved configuration discussed in greater detail below. The material is preferably flexible so as to be capable of conforming to any curvature of the headlamp surface. It can be clear or tinted, for example with amber tinting to meet French regulations.

The optically deflecting material should have an area and shape that will cover substantially all of the portion of the headlamp surface through which the dipped beam is projected but should not extend beyond this portion in a way that would deflect substantial other portions of the main beam. According to the invention this is achieved by making the optically deflecting material of generally wedge shape.

As viewed from outside the headlamp with the patch in place, and regarding the front of the lamp as a clock face, the optically deflecting material covers an area which overlaps much of the sector between 8 o'clock and 9 o'clock for British cars and 3 o'clock and 4 o'clock for Continental cars. The top edge of the area is preferably horizontal and the left hand and right hand edges at right angles thereto. The bottom edge is preferably at an angle in the range 10 to 30"C to the top edge.

For a patch to convert from British to Continental use the optically deflecting area should have a left hand edge of greater length than its right hand edge and should preferably be positioned with its top edge in alignment with the centre horizontal line of the headlamp front surface and its top right hand corner close to the centre point of the headlamp front surface. For a patch to convert from Continental to British use the optically deflecting area should have a right hand edge longer than the left hand edge and the area should preferably be installed with its top edge similarly in alignment with the centre horizontal line of the headlamp front surface and its top left hand corner close to the centre point of the headlamp front surface.

The optically deflecting area can either form substantially or entirely the whole of the patch or alternatively can form an optically deflecting zone within a transparent (non-deflecting) sheet material which extends across other portions or the whole of the headlamp frontal area. Such a patch to cover the whole frontal area offers the advantage of making the patch less likely to be dislodged by headlamp washing sprays or wiper blades. In versions of the patch which do not extend over the whole frontal area of the lamp the circumference of the patch is preferably bevelled to reduce the risk of such dislodging.

The optically deflecting properties are preferably provided by parallel grooves extending from top to bottom of one surface of the optically deflecting area so as to give a series of inclined surfaces across its width. The angle of the inclined surfaces is chosen to give the desired deflection, having regard to the refractive index of the patch material. For material with a refractive index at or near to 1.5 the inclination is usually in the range 20 to 30 to the surface of the patch. Each of the inclined surfaces normally has the same angle of inclination as its neighbours, although different inclinations can be provided if required so as to alter the spread of the beam.

The number of grooves should generally be in the range 0.5 to 10 per mm of width (i.e. the distance between the left and right edges) of the optically deflecting area and is preferably in the range 1 to 5 per mm of the said width. The choice of number of grooves determines the minimum thickness of the patch: a large number of small grooves permits the use of thin material; a small number of larger groooves requires thicker material. Subject to this choice the patch thickness should generally be in the range 0.25 to 3.0mm. With a number of grooves in the preferred range of 1 to 5 per mm of width, the thickness of the grooved material can be kept relatively small, for example in the range 0.25 to 2.0mm.

Viewed from the edge of the deflecting area the grooves extend across its width in a saw-tooth pattern. The edges of the teeth opposite to the edges which are inclined to effect the deflection may either be at right angles to the patch surface or at an angle either slightly greater than or slightly less than a right angle thereto.

The grooves can be formed by a wide variety of methods, depending upon the choice of optically deflecting material.

For moulded plastics, produced for example by injection moulding, the grooves can be produced by the moulding step.

Injection moulding provides the advantage that the finished patch can be given a polished surface which ensures very good optical properties. Alternatively the grooves can be produced either by an embossing step in a calendering process or by warming a plastics material to soften it and then applying a embossing roller.

If desired, the outer edge of the patch can be provided with a rim to abut the lamp surface at all points around the rim. For a patch on which the grooves are provided on the surface next to the lamp surface, the rim acts to prevent penetration of road grime into any spaces between the patch and the lamp surface. The rim can conveniently be made of the same material as the optically deflecting area, and integral with it, but should preferably be free of grooves.

Suitable means of attachment of the patch to the headlamp surface include adhesives or mechanical attachments.

In one preferred embodiment of the invention an adhesive pad is provided at each corner of the patch. In another preferred embodiment an adhesive strip is located around a peripheral rim on the patch. In both of these embodiments the adhesive is preferably covered by a non-adhesive backing strip which is removed when the patch is about to be applied to the lamp. In another version the attaching means comprises two or more transparent guide plates to be held permanently on the headlamp and the patch is inserted or withdrawn as required into the position defined by the guide plates.

In a further preferred embodiment of the invention, adhesion is achieved by forming the patch from a flexible plastics material with self-adhesive properties, for example highly plasticised pvc, sometimes known as window-stick quality. This material is simply pressed on the headlamp surface at the required point and, provided it is kept clean, can be repeatedly removed and reapplied, for example for future overseas visits. If desired the self-adhesive properties can be protected before and between duties by a non-adhesive backing strip.

In one convenient embodiment of the invention the patch is formed by two layers of flexible plastics material and the required grooves are provided on the inner surface of one of the layers. In this embodiment the tooth-points of the grooves are preferably slightly levelled so as to assist adhesion to the other layer of plastics material. The layers are preferably joined to each other by heat sealing around their periphery. This embodiment offers a great degree of choice in the configuration of the patch. For example the layer with grooves can be of material of a thickness to accommodate the grooves, whereas the other layer can be of thinner material. Either one or both layers can be tinted.

This layered construction offers significant advantages in keeping the grooves clean and undamaged and therefore in allowing for repeated re-use of the patch.

The invention offers the advantage over the opaque patch system that selection from a small standard range of sizes of patch can accommodate virtually every size and shape of headlamp. Indeed a single size of patch has been found to be suitable for almost all of the current range of vehicle headlamps. The need to determine the precise outline for every variety of lamp and then to trim each patch to the required outline is thus avoided. In terms of light transmission the deflecting patch simply redirects the dipped portion of the beam, and even that portion merely passes through a thin additional layer or layers of transparent material, such that transmission losses are minimal.If the closest available size of optically deflecting area does extend into a portion of the full beam the unintended deflection of this portion is not significant in terms of light output either for the dipped beam or for the full beam.

The invention is further described with reference to the accompanying drawings in which Figure 1 is an actual size elevation of a transparent patch according to the invention for use on a right hand drive vehicle.

Figure 2 is a portion of a cross section of the patch illustrated in Figure 1, taken along the line A-A', but shown on a much enlarged scale. The arrows T indicate the forward direction of travel of the vehicle.

Figure 3 is an elevation of the Figure 1 patch in position on a headlamp.

Figure 4 is an actual size elevation of a second version of transparent patch according to the invention, also for use on a right hand drive vehicle, and as would be viewed from inside the headlamp.

Figure 5 is a cross section of the patch illustrated in Figure 4, taken along the line B-B'.

The patch illustrated in Figures 1 to 3 comprises two layers, 1 and 9, of transparent pvc sheet. One layer is an amber-coloured sheet 1 of 0.4 mm thickness with a plurality of parallel grooves 3 on one surface. For the purposes of illustration in figures 1 and 3 only every fifth groove 3 is indicated; in figure 2 the grooves 3 are shown at an enlarged scale relative to the rest of the figure. Each groove 3 comprises an inclined surface 5 and a surface 7 substantially at right angles to the plane of the sheet. The inclined surfaces 5 form an angle of 25 to the plane of the sheet.

The pitch of the grooves 3 is 0.4mm i.e. 2.5 grooves per mm.

The other layer 9 is colourless highly plasticised pvc sheet of 0.4 mm thickness and with no grooves. The layers 1 and 9 are joined around the periphery of layer 1 by a heat seal 11, with the grooved surface of the layer 1 facing the layer 9. The peaks 4 between adjacent grooves 3 are slightly levelled so as to encourage adhesion between the levelled areas 4 and the other layer 9. The layer 9 overlaps the layer 1 by a width of approximately 5 mm around its periphery. Both layers 1 and 9 may have bevelled edges 13 around their peripheries.

The configuration of layers 1 and 9 of this particular version requires the amber layer 1 to be the outermost layer when the patch is in place on a headlamp.

The patch illustrated in Figures 4 and 5 comprises a single layer, 1.2 mm thick, of injection-moulded amber-tinted transparent polycarbonate with a refractive index of 1.5. The inner surface of the patch, i.e the surface to be located against the headlamp surface, has parallel grooves 3 with a pitch of lmm, i.e 1 groove per mm of patch width. For ease of illustration the grooves in Figures 4 and 5 are shown diagrammatically and not to scale. Each groove 3 comprises an inclined surface 5, forming an angle of 240 to the plane of the patch, and a surface 7 substantially at right angles to the plane of the patch.

A peripheral rim 15 extends around the inner surface and carries an adhesive layer 17 and protective peel-off paper strip 19 (items 17 and 19 also not shown to scale). A peripheral bevelled edge 13 is provided on the outer surface of the patch opposite the peripheral rim 15.

Patches according to the invention can conveniently be offered in a two-patch pack, one for each of the vehicle headlamps, together with, for example, a solvent-impregnated cleaning pad to facilitate the cleaning of the headlamp surfaces before application and instructions indicating to the user the way in which to apply the patches to the headlamps.

Alternatively, the patch itself can carry instructions or markings on how to apply it.

The user selects a patch of suitable type and size and attaches it to the front of a headlamp so as to cover the segment through which the dipped beam emerges. Surface markings on the headlamp glass usually clearly indicate the required position. The grooves should be aligned as close to the vertical as the curvature and slope of the headlamps permit so as to ensure that the beam deflection is in a lateral as distinct from vertical direction.

On return from the foreign trip which required their installation the user simply removes the patches for storage and possible re-use for a future trip.

Claims

1. A light-deflecting patch for a dipped beam from a vehicle headlamp which patch comprises a transparent optically deflecting material shaped to cover the portion of the headlamp surface through which the dipped beam is projected.

2. A light-deflecting patch as claimed in claim 1, in which the optically deflecting material is a transparent plastics material selected from polyvinyl chloride, polycarbonate, polyacrylates and polystyrene.

3. A light-deflecting patch as claimed in claim 1 or claim 2, in which the optically deflecting material is flexible so as to conform to the curvature of the headlamp surface.

4. A light-deflecting patch as claimed in any preceding claim, in which the optically deflecting material is amber-tinted.

5. A light-deflecting patch as claimed in any preceding claim, in which the optically deflecting material is generally wedge shaped.

6. A light-deflecting patch as claimed in claim 5, in which the optically deflecting material is of a shape that when in position on a vehicle headlamp its top edge is horizontal, its left hand and right hand edges are at right angles thereto and its bottom edge is at an angle in the range 10 to 30"C to its top edge.

7. A light-deflecting patch as claimed in any preceding claim, in which the optically deflecting properties are provided by parallel grooves extending from top to bottom of one surface of the optically deflecting material so as to give a series of inclined surfaces across its width.

8. A light-deflecting patch as claimed in claim 7, in which the optically deflecting material has a refractive index at or near to 1.5 and the inclined surfaces are at an angle in the range 20 to 30 to the surface of the patch.

9. A light-deflecting patch as claimed in claim 7 or claim 8, in which the number of grooves is in the range 1 to 5 per mm of width of the optically deflecting material.

10. A light-deflecting patch as claimed in any preceding claim, which has a thickness in the range 0.25 to 3.0mm.

11. A light-deflecting patch as claimed in any preceding claim, in which the optically deflecting material forms the whole or substantially the whole of the patch.

12. A light-deflecting patch as claimed in any of claims 1 to 10, in which the optically deflecting material forms an optically deflecting zone within a transparent sheet material which extends across other portions or the whole of the headlamp frontal area.

13. A light-deflecting patch as claimed in any preceding claim, which has a rim around its outer edge to abut the lamp surface.

14. A light-deflecting patch as claimed in any preceding claim, including adhesive means for attachment to the headlamp surface.

15. A light-deflecting patch as claimed in any of claims 1 to 13, including mechanical means for attachment to the headlamp surface.

16. A light-deflecting patch as claimed in claim 14, in which an adhesive pad is provided at each corner of the patch.

17. A light-deflecting patch as claimed in claim 13 and claim 14, in which an adhesive strip is located around the peripheral rim.

18. A light-deflecting patch as claimed in claim 14, which is formed from a flexible plastics material with self-adhesive properties.

19. A light-deflecting patch as claimed in any of claims 16, 17 and 18, in which the adhesive is covered by a non-adhesive backing strip which is removed when the patch is about to be applied to the headlamp.

20. A light-deflecting patch as claimed in any of claims 1 to 10, which is formed by two layers of flexible plastics material.

21. A light-deflecting patch as claimed in claim 20, in which the optical deflection is provided by grooves on the inner surface of one of the layers.

22. A light-deflecting patch as claimed in claim 21, in which the tooth-points of the grooves are slightly levelled so as to assist adhesion to the other layer of plastics material.

23. A light-deflecting patch as claimed in any of claims 20 to 22, in which the layers are joined to each other by heat sealing around their periphery.

24. A light-deflecting patch as claimed in claim 1, substantially as described herein.