FR2788585A1 - Elliptical projector for vehicle lighting assemblies, comprises a light source placed within projector and mounted behind a lens and cover assembly - Google Patents

Abstract

The refector (2) is in the form of an ellipse and has mounted within it a light source (4). A cover (8) is mounted in front of the projector and is covered by a lens (10) assembly to form the lighting unit for a vehicle.

Description

The present invention relates to projectors

  of the elliptical type, in particular for motor vehicles.

  Projectors of the elliptical type include a concave reflector, essentially in the shape of an ellipsoid of revolution and which consequently has two focal points. A light source is placed in the vicinity of the focal point closest to the reflector, generally called the first focal point. At the front of the reflector is a plano-convex lens, the focal point of which is located in the second focal point of the

reflector.

  When the projector must perform a function whose lighting has a cut-off, such as the "code" function, a screen or cover is further provided in the region of the common focus of the lens and the reflector; this screen stops part of the light rays coming from the reflector to form the desired cut. A disadvantage of this conventional embodiment is that too little light is emitted above the cut. Indeed, even if the beam emitted by the projector must include a clear area (below the cut-off) and a dark area (above the cut-off), photometric regulations prescribe minimum illumination in the dark area; these minima are also desirable so as not to leave the upper part of the field of vision completely in the dark

of the driver.

  In order to remedy this drawback, it has already been proposed, as described for example in the German utility model n 90 00 395, to place on the outside face of the lens deviating means which

  part of the light beam.

  This known design has the drawback, however, that the deflecting means are visible from the outside of the projector, which affects the aesthetic appearance of the latter. This drawback is all the more annoying since the elliptical type headlamps are justly appreciated for the aesthetic aspect as their

  confers the presence of the lens.

  In order to solve this problem, the present invention provides a headlamp, in particular for a motor vehicle, comprising an essentially elliptical reflector, a light source mounted in the reflector, a lens and a cover placed between the reflector and the lens, in which the lens carries light deflection means, characterized in that the deflection means are located on the face of the

  lens facing the reflector.

  Preferably, the deflecting means comprise a prism; - The ratio between the height of the prism and the radius of the lens is between 0.1 and 0.3; - Said face is essentially plane and the prism is formed by an inclination of said face; - Said inclination is between 1 and; - Said inclination is worth approximately 3; - the prism is formed in the upper part of the lens; - the prism is formed in the lower part of the lens; - the face of the lens facing outwards

is smooth.

  Other characteristics and advantages of the invention will appear better in the light of the

  following description made with reference to the drawings

  attached in which: - Figure 1 is a schematic section showing the essential elements of a projector according to an embodiment of the invention; - Figure 2 is an enlarged view of the lens of the projector of Figure 1; - Figure 3 shows by means of isocandela curves the light beam generated by a projector of the conventional elliptical type; - Figure 4 shows by means of isocandela curves the light beam generated by the projector of Figure 1; FIG. 5 represents a variant of

realization of the lens.

  FIG. 1 represents the essential elements of a projector of the elliptical type, namely a reflector 2, a lamp 4 (here a discharge lamp) carrying a light source 6, a cover 8 and a

lens 10.

  The lens 10 is of the plano-convex type: it has a first essentially flat face 14 facing the reflector 2 and a second face 18 facing the outside of the projector. More specifically, said first face 14 is formed on a cylindrical collar 16. Said first face carries a prism 12 which constitutes a means deflecting light. In the example shown, the prism 12 is formed by an inclination a of said first face 14 throughout its lower region. On the contrary, said second face 18

is smooth.

  In order to return enough light to

  above the cut without however modifying the beam too much, the ratio between the height h of the prism 12 and the radius r of the lens 10 (at the collar 16) is advantageously between 0.1 and 0.3. Good results (see Figure 4) are obtained with a prism 12 which extends over a height of 7 nmm for a

lens 10 with a radius of 32 mmn.

  The inclination a of the prism 12 relative to the essentially planar face 14 is preferably between 1 and 10. Good results are obtained (Figure 4)

with an inclination a of 3.

  FIG. 3 represents for comparison the beam created by a projector of the conventional elliptical type, that is to say of which the lens does not include the prism described above. We observe that this beam has a very marked cut above which

  the projector emits very little light.

  On the contrary, and as clearly visible in FIG. 4, the projector described above emits notably light above the cut-off, without prejudice either to the photometry of the beam under the cut-off

  nor to the external appearance of the projector.

  The invention is of course not limited to the embodiment described. In particular, provision could be made to place the prism forming a light deflection means in the upper part of the lens, as shown in

figure 5.

Claims (9)

  1. Projector, in particular for a motor vehicle, comprising a reflector (2) which is essentially elliptical, a light source (6) mounted in the reflector (2), a lens (10) and a cover (8) placed between the reflector (2 ) and the lens (10), in which the lens (10) carries light deflection means (12), characterized in that the deflection means (12) are located on the face (14) of the lens (10) tour towards the reflector (2).   2. Projector according to claim 1, characterized in that the deflecting means (12) include a prism (12).   3. Projector according to claim 2, characterized in that the ratio between the height (h) of the prism (12) and the radius (r) of the lens (10) is between 0.1 and 0.3.   4. Projector according to one of claims 2 to 3, characterized in that said face (14) is essentially planar and in that the prism (12) is   formed by an inclination (a) of said face.   5. Projector according to claim 4, characterized in that said inclination (a) is included between 1 and 100.   6. Projector according to claim 4, characterized in that said inclination (a) is approximately 35.   7. Projector according to one of claims 1 to   6, characterized in that the prism (12) is formed in   upper part of the lens (10).   8. Projector according to one of claims 1 to 6, characterized in that the prism (12) is formed in   lower part of the lens (10).   9. Projector according to one of claims 1 to 8, characterized in that the face (18) of the lens (10)   facing outward is smooth.