GB1604465A

GB1604465A - Motor vehicle headlamp

Info

Publication number: GB1604465A
Application number: GB22267/78A
Authority: GB
Original assignee: Ducellier et Cie
Current assignee: Ducellier et Cie
Priority date: 1977-05-25
Filing date: 1978-05-25
Publication date: 1981-12-09
Also published as: DE2822820A1; IT1098215B; FR2392322A1; FR2392322B1; ES470036A1; IT7823639A0

Description

(54) A MOTOR VEHICLE HEADLAMP (71) We, DUCELLIER & CIE, a French Company of Echat 950, 94024 Creteil Cedex France do hereby declare the invention for which we pray that a patent may be granted to us, the method by which it is to be performed to be particularly described in and by the following statement:- This invention relates to a headlamp for motor vehicles which will produce a dipped beam satisfying regulations 8 and 20 of the United Nations on Halogen Lamps. Such headlamps are normally provided either with a shield defining a pattern of light emission permitting the production, in normal conditions of use, of the so-called "Standard European Dipped Beam", or are alternatively surrounded by a mask producing the same light emission pattern.

These new regulations 8 and 20 provide a choice between the present dipped beam pattern and a new dipped beam pattern, shown respectively in Figures 1 and 2 of the accompanying drawings. The cut-off pattern of the dipped beam presently Prescribed by the road code (Figure 1) must have a horizontal plane h H on one side of a vertical plane, namely that side remote from the direction of oncoming traffic, which may be to the left or to the right depending on the conditions of use of the headlamp; at the other side of the vertical plane, the cutoff pattern has a plane H H3 inclined by no more than 150 to the horizontal h h.

A cut-off pattern of the new dipped beam which is also permissible in accordance with the aforesaid United Nations regulations 8 and 20 (Figure 2) has, on one side a horizontal plane portion h H but on the other side has two planes, namely a plane H H1 making an angle of 45" with the horizontal h h, and a horizontal plane Hl H4 displaced in height by 1% with respect to the horizontal h h.

Some lamps presently on the market provide a cut-off beam pattern shown in Figure 1 by virtue of the shape of their shields and of the position of their dipping filaments which are approximately parallel to the axis of the lamp reflector; they do not, however, permit the production of the cut-off beam pattern shown in Figure 2, because the filaments are approximately parallel with the straight edges ofthe shield.

It is known from Applicants British Patent No. 1380495 to obtain the new cutoff beam pattern of Fig. 2 from a twin filament halogen lamp by rotating the lamp about the axis of its dipping filament relative to its normal position and also inclining the axis of that filament relative to the axis of the reflector so as to obtain a cutoff beam pattern constituted by two horizontal substantially aligned plane portions, and then producing a beam portion displaced in height by 1% either by the addition of a reflecting element disposed in the vicinity of the main reflector, or by local deformation of the main reflector, or by means of the lamp lens or by the local elimination of part of the reflector.

However, this lamp can be difficult to make because of the complex shape of the reflector, and/or lens and an object of this invention is to provide a headlamp of relatively simple concept and construction which is capable of producing this new cutoff beam pattern of Fig. 2.

According to the present invention, a motor vehicle headlamp for producing a dipped beam having a cut-off pattern satisfying United Nations Halogen lamp regulations 8 and 20 as shown in Fig. 2 of the accompanying drawings, said headlamp having a reflector, a lamp glass and a dipping filament, the reflector having at least two parabolic portions having a common focus, the axis of revolution of one being angularly displaced with respect to the axis of revolution of the other in the vertical plane containing the axis of the lamp filament to thereby displace the levels of the two plane portions of the cut-off pattern, the lamp glass being arranged to shape the beam as to produce the parts of the beam inclined to the horizontal at one side of the vertical line separating the two plane portions.

The invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 represents the cut-off pattern of the present or "Standard European Dipped Beam".

Figure 2 represents the cut-off pattern of the new dipped beam in accordancce with regulations 8 to 20 referred to above; Figure 3 represents schematically the theoretical surface of the beam emitted by the dipping filament of a lamp provided with an occulting shield and of which the intersection with a plane P defines the cutoff pattern of the present diPped beam: Figure 4 represents the diagram of the intermediate beam obtained after rotation and inclination of the lamp; Figure 5 represents schematically the theoretical surfaces of the beam emitted by the dipping filament of a lam provided with an occulting shield and of which the intersection with the plane P defines the cut-off pattern of the new dipped beam of the aforesaid regulations 8 and 20 obtained by the headlamp of the invention.

From a two filament lamp providing a dipped beam of which the cut-olf pattern is detained by Figure 1, it is known to transform this cut-off pattern to that represented in Figure 4 by rotating the lamp about its axis and inclining it with respect to the axis of the reflector.

Figure 3 represents schematically the beam emitted from the dipping filament of a twin filament lamp, the beam having plane portions corresponding to the wings la, ib of the shield 1 and defining on a plane P, perpendicular to the axis of the lamp, the present cut-off pattern h, H3. It is to be noted that the beam portion reflected by the right-hand portion 3 of the reflector viewed from the front intersects the plane P on its left portion, producing the raised part of the cut-off pattern HH3; it is thus this portion 3 which must be deflected in order to provide the required height displacement.

According to the invention and following Figure 5, the reflector portions 3 and 4 are of parobolic form, being of the same focal length and having the same focus. The axis of revolution of the reflector portion 4 is angularly displaced relative to that of the portion 3 in the vertical plane containing the axis of the lamp filament thus raising the plane portion 7rl (Figure 3) and consequently enabling the portion Hl H4 of Figure 2 to be obtained.

Because of the presence of the shield at the level of the filament there exists a substantially unilluminated area in the region of the point H and it is known to use the lamp glass to shape the beam so as to direct the light towards this point in order to produce that portion H Hl of the present beam which is inclined at 150. The same means is used in the headlamp of the invention in order to obtain the oblique 45" segment of the view dipped beam of Figure 2.

This principle can also be used in the case of a halogen lamp having a single filament.

In this case the arrangement will be simplified because the shield, which does not form an integral art of the lamp, will~be defined in order to obtain by a conventional position of the lamp, a cut-off pattern such as that represented in Figure 4. It would then only be necessary to rotate the necessary part of the reflector to obtain the cut-off pattern HI H4, and to produce an adequate lens to obtain the necessary illumination in the zone H Hl. In this case, there is no black hole and light is reflected to obtain the sector HH1.

In a modified arrangement the inclined portion of the reflector could be just the portion providing the cut-off pattern or a sector of the reflector containing this pdrtion, or half of the reflector considered.

Moreover, by the choice of the sector of the reflector to be inclined, it would be possible to obtain a cut-off approaching as nearly as possible the beam defined in Figure 4 and particularly at the level of the unilluminated area in the region of the point H.

WHAT WE CLAIM IS: 1. A motor vehicle headlamp for producing a dipped beam having a cutoff pattern satisfying United Nations Halogen lamp regulations 8 and 20 as shown in Fig. 2 of the accompanying drawing, said headlamp having a reflector, a lamp glass and a dipping filament, the reflector having at least two parobolic portions having a common focus, the axis of revolution of one being angularly displaced with respect to the axis of revolution of the other in the vertical plane containing the axis of the lamp filament to thereby displace the levels of the two plane portions of the cut-off pattern, the lamp glass being arranged to shape the beam so as to produce the part of the beam inclined to the horizontal at one side of the vertical line separating the two plane portions.

2. A headlamp according to Claim 1, for use with a twin filament lamp wherein an occulting shield is arranged to produce a cut-off beam pattern corresponding to that shown in Fig. 3 of the accompanying drawings, the portion H H3 of the pattern being raised by the relative angular displacement of said reflector portions to produce the plane portions Hl H4 of Fig. 2 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. side of the vertical line separating the two plane portions. The invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 represents the cut-off pattern of the present or "Standard European Dipped Beam". Figure 2 represents the cut-off pattern of the new dipped beam in accordancce with regulations 8 to 20 referred to above; Figure 3 represents schematically the theoretical surface of the beam emitted by the dipping filament of a lamp provided with an occulting shield and of which the intersection with a plane P defines the cutoff pattern of the present diPped beam: Figure 4 represents the diagram of the intermediate beam obtained after rotation and inclination of the lamp; Figure 5 represents schematically the theoretical surfaces of the beam emitted by the dipping filament of a lam provided with an occulting shield and of which the intersection with the plane P defines the cut-off pattern of the new dipped beam of the aforesaid regulations 8 and 20 obtained by the headlamp of the invention. From a two filament lamp providing a dipped beam of which the cut-olf pattern is detained by Figure 1, it is known to transform this cut-off pattern to that represented in Figure 4 by rotating the lamp about its axis and inclining it with respect to the axis of the reflector. Figure 3 represents schematically the beam emitted from the dipping filament of a twin filament lamp, the beam having plane portions corresponding to the wings la, ib of the shield 1 and defining on a plane P, perpendicular to the axis of the lamp, the present cut-off pattern h, H3. It is to be noted that the beam portion reflected by the right-hand portion 3 of the reflector viewed from the front intersects the plane P on its left portion, producing the raised part of the cut-off pattern HH3; it is thus this portion 3 which must be deflected in order to provide the required height displacement. According to the invention and following Figure 5, the reflector portions 3 and 4 are of parobolic form, being of the same focal length and having the same focus. The axis of revolution of the reflector portion 4 is angularly displaced relative to that of the portion 3 in the vertical plane containing the axis of the lamp filament thus raising the plane portion 7rl (Figure 3) and consequently enabling the portion Hl H4 of Figure 2 to be obtained. Because of the presence of the shield at the level of the filament there exists a substantially unilluminated area in the region of the point H and it is known to use the lamp glass to shape the beam so as to direct the light towards this point in order to produce that portion H Hl of the present beam which is inclined at 150. The same means is used in the headlamp of the invention in order to obtain the oblique 45" segment of the view dipped beam of Figure 2. This principle can also be used in the case of a halogen lamp having a single filament. In this case the arrangement will be simplified because the shield, which does not form an integral art of the lamp, will~be defined in order to obtain by a conventional position of the lamp, a cut-off pattern such as that represented in Figure 4. It would then only be necessary to rotate the necessary part of the reflector to obtain the cut-off pattern HI H4, and to produce an adequate lens to obtain the necessary illumination in the zone H Hl. In this case, there is no black hole and light is reflected to obtain the sector HH1. In a modified arrangement the inclined portion of the reflector could be just the portion providing the cut-off pattern or a sector of the reflector containing this pdrtion, or half of the reflector considered. Moreover, by the choice of the sector of the reflector to be inclined, it would be possible to obtain a cut-off approaching as nearly as possible the beam defined in Figure 4 and particularly at the level of the unilluminated area in the region of the point H. WHAT WE CLAIM IS:

1. A motor vehicle headlamp for producing a dipped beam having a cutoff pattern satisfying United Nations Halogen lamp regulations 8 and 20 as shown in Fig. 2 of the accompanying drawing, said headlamp having a reflector, a lamp glass and a dipping filament, the reflector having at least two parobolic portions having a common focus, the axis of revolution of one being angularly displaced with respect to the axis of revolution of the other in the vertical plane containing the axis of the lamp filament to thereby displace the levels of the two plane portions of the cut-off pattern, the lamp glass being arranged to shape the beam so as to produce the part of the beam inclined to the horizontal at one side of the vertical line separating the two plane portions.

3. A headlamp according to Claim 1 for

use with a single filament lamp wherein an occulting shield is arranged to produce a cut-off beam pattern corresponding to that shown in Fig. 4 of the accompanying drawings, one of the resulting plane portions H h being displaced by the relative angular displacement of said reflector portions to produce the plane portion Hl H4 of Fig. 2 of the accompanying drawings.

4. A motor vehicle headlamp having a reflector substantially as hereinbefore described, with reference to Fig. 5 of the accompanying drawings.