Patent Grant
9677734
This application claims priority to PCT Application PCT/EP2012067068 filed Sep. 3, 2012, and also to French Application No. 1157800 filed Sep. 2, 2011, which are incorporated herein by reference and made a part hereof.
1. Field of the Invention
The present invention relates to an optical device, notably for a motor vehicle, such as a lighting and/or signaling and/or interior lighting device, notably having a photometric function which is helpful for the use of the vehicle on the road in that it enables the vehicle to be seen by other vehicles or enables the driver of said vehicle to see outside the vehicle.
2. Description of the Related Art
In the field of signaling, as well as in that of lighting, numerous regulatory constraints allow little scope for changes in the appearance of the lights in the illuminated condition, since the photometric characteristics of the light beams are very closely specified. However, style and aesthetic factors are very important features of this type of product, and vehicle parts manufacturers try to provide their products with a “signature” which makes them easily recognizable by the end user.
It is known to use surface light sources to provide lighting and/or signaling and/or interior lighting functions for motor vehicles. A new type of surface light source is being developed at present, in the form of organic light-emitting diodes. It would be helpful to use these to provide lighting and/or signaling functions. However, these sources have some drawbacks. The degrees of directivity achieved at present are of the form (cos θ)11, where θ represents the emission angle with respect to the normal to the emission surface and (cos θ)11 represents the intensity of the light emitted in the direction θ relative to the intensity emitted in the direction of the normal to the surface. This degree of directivity is insufficient for the effective provision of certain signaling functions, notably a brake signaling function. This is because, in order to provide this signaling function, greater directivity is required in the vertical plane; in other words, the light emitted by the diode must be less diffused vertically.
To overcome this drawback, there are known organic light-emitting diodes that have a layer on their emitting surface for modifying their directivity. In this way, a directivity of the form (cos θ)15 is achieved, where θ represents the emission angle with respect to the normal to the emission surface and (cos θ)15 represents the degree of illumination in the direction θ. By contrast with the situation described previously, this solution results in a directivity in the horizontal plane which is too great for the provision of a brake-type signaling function.
Consider a rectangular organic light-emitting diode having an emitting surface of 5 mm by 220 mm, positioned perpendicularly to an optical axis and having a global emission indicator of cos11 times the angle of observation with respect to its normal. This gives us the distribution at infinity shown in
Additionally, the levels of luminance produced by organic light-emitting diodes are limited. It is therefore necessary to provide extended emission areas in order to obtain a lighting and/or signaling function.
The object of the invention is to provide an optical device which overcomes the aforementioned drawbacks and which improves the known optical devices of the prior art. In particular, the invention proposes a simple and inexpensive optical device enabling organic light-emitting diodes of limited dimensions to be used to provide lighting and/or signaling and/or interior lighting functions for a motor vehicle.
According to the invention, an optical device for a motor vehicle, notably a lighting and/or signaling and/or interior lighting device for a motor vehicle, comprises a surface light source and a light beam shaping member which deflects first light rays of the beam emitted by one face of the surface light source, this member not deflecting second light rays of the beam emitted by the same face of the surface light source.
The emission area of the surface light source may be greater than 1 cm2, or greater than 5 cm2, or greater than 10 cm2.
The surface light source may comprise an organic light-emitting diode.
The optical device may comprise a housing closed by a closing outer lens, within which housing the surface light source and the shaping member are located.
The shaping member may be formed by a transparent one-piece component.
The shaping member may comprise a deflecting element which deflects the rays mainly by reflection.
The deflecting element may comprise a first reflecting element, notably a first flat reflecting element, and a second reflecting element, notably a second reflecting element with a parabolic section whose focus is at the position of the image of the center of the face seen via the first reflecting element, or substantially at the position of the image of the center of the face seen via the first reflecting element.
The shaping member may comprise a deflecting element which deflects the rays mainly by refraction.
The deflecting element may comprise an upper part and a lower part, the lower and upper parts being connected by a mechanical connecting element.
The first and second rays may pass through the shaping member.
Another object of the invention is a motor vehicle comprising an optical device as defined above.
These and other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.
The attached drawing shows, by way of example, different embodiments of a lighting and/or signaling device for a motor vehicle according to the invention.
A first embodiment is described below with reference to
The surface light source 3 is rectangular and elongated. For example, it measures about 220 mm in length and about 5 mm in height. The surface light source 3 is intended to be mounted so as to extend horizontally, with its light-emitting face 31 oriented vertically. The optical axis 90 of the optical device 1 is perpendicular to this light-emitting face 31. It cuts the surface light source 3 in the center of the height of the face, preferably in the center F of the light-emitting face 31.
The shaping member 2 is made of transparent material such as polymethyl methacrylate (PMMA). It is made, for example, by extrusion or molding. The shaping member 2 extends parallel to the length of the surface light source 3. For example, the cross section of the shaping member 2 remains constant over the whole length of the surface light source 3. Alternatively, the cross section may vary to create stylistic effects.
The shaping member 2 comprises an upper part 41, a central part 42 (half of which is shown) and a lower part (not shown in
The upper part 41 forms a first assembly allowing rays emitted by the surface light source 3 to pass out of an output face 25 of the first assembly in a direction substantially parallel to the optical axis 90.
The lower part 43 forms a second assembly allowing rays emitted by the surface light source 3 to pass out of a second output face of the second assembly in a direction substantially parallel to the optical axis 90.
The central part 42 has the function of mechanically connecting the upper part 41 to the lower part 43. It is also made of transparent material so that rays emitted by the surface light source 3 can pass through it. This passage takes place without deflection (or without significant deflection) of the light rays emitted by the surface light source 3.
Thus, by means of the beam shaping device, light is emitted from the output of the optical device 1 in three bands 101, 102, 103, as shown in
The first light rays 202, 203 emitted by the surface light source 3 form a sufficiently large angle with the optical axis 90 in the plane P to prevent them from passing through the central part 42 of the shaping member 2. This plane P is preferably a vertical plane normal to the face 31 of the surface light source 3. Thus, these first light rays are emitted toward the upper part 41 (or the lower part 43), enter this part at a surface 26, and are guided by the part as described below. When the rays are inside the upper part 41, a first reflecting element 22, formed for example by a face of the shaping member 2, deflects the rays by reflection. This reflection is obtained, for example, as a result of total reflection at an optical surface, the refractive index of the upper part being greater than that of the environment in which it is located. Alternatively, the first reflecting element 22 may be treated, by metal coating for example. Having been reflected, the first rays are reflected again by a second reflecting element 24, formed for example by a second surface. This reflection is obtained, for example, as a result of total reflection at an optical surface, the refractive index of the upper part being greater than that of the environment in which it is located. Alternatively, the second reflecting element 24 may be treated, by metal coating for example. A surface 23 is provided to connect the surface 26 to the second reflecting element 24.
The first reflecting element 22 is preferably flat and the second reflecting element 24 is, for example, cylindrical with a parabolic section, the focus F′ of the parabola being at the position of the image of the center F of the face 31 seen via the first reflecting element 22.
Having been reflected, the first rays are again deflected if necessary by passing through an optical surface at the output surface 25 of the guide. In fact, this face may form an angle δ with the vertical plane.
The second light rays 201 emitted by the surface light source 3 form a sufficiently small angle with the optical axis 90 in the plane P to pass through the central part 42 of the shaping member 2. Thus these second light rays are emitted outside the shaping member 2, at the position of the central part 42. For this purpose, the second light rays pass through a first optical surface 28 as they enter the shaping member 2, then through a second optical surface 27 as they pass out of the shaping member 2. Consequently they pass out of the shaping member 2 at a face 21 formed by the second optical surface 27.
The three bands 101, 102 and 103 are in fact formed by the light rays passing out of the faces 21 and 25, and out of another face, which is not shown, of the lower part of the shaping member 2. Given the geometry of the shaping member 2, it should be noted that, when a viewer moves away from the optical axis 90 through 10° in a horizontal plane, all the bands remain visible. On the other hand, when a viewer moves away from the optical axis 90 through 10° in a vertical plane, the bands disappear. This is because, as shown in
For the global beam emitted from the optical device, the distribution at infinity shown in
In the first embodiment of the optical device 1, the shaping member 2 is, for example, made as a single extruded part having a length greater than or equal to that of the surface light source 3 (220 mm in the example), with a cross section constructed as follows:
The cross section of the central part 42 is a portion of a ring with an internal radius r1 such that 2×r1 is greater than and (in order to minimize the overall dimensions of the system) preferably close to the height of the surface light source 3 (for example, if the surface light source 3 height is 5 mm, r1 can be made equal to 3.5 mm), and with an external radius r2 which is as small as possible while remaining compatible with the manufacture of the shaping member 2 and/or with its function as a mechanical connection between the upper part 42 and lower part 43 (for example, r2−r1=2.5 mm).
An angle α between a straight line D, passing through the upper edge of the organic light-emitting diode, and the optical axis 90 defines half of the vertical aperture of the field in which the surface light source 3 is fully visible in the central band. The rays seen in this field are not deflected by the shaping member 2. For example, α=5°.
An angle β between the straight line D and the normal to the first reflecting element 22 is greater than or equal (preferably equal, to minimize the overall dimensions of the shaping member 2) to the angle of total reflection in the material of the shaping member 2 (for PMMA, β=a sin(1/1.49), therefore β=42.2°). In these conditions, all the rays emitted from the surface light source 3 and striking the first reflecting means 22 undergo total reflection.
An angle γ above which, given the directivity of the surface light source 3, the emitted light may be considered negligible, in other words such that
is negligible relative to 1.
In the example, if k=11 and γ=37°, the above ratio is 0.067.
F′ is the mirror image of F with respect to the plane of the first reflecting means 22.
M is the intersection of the internal reflection of the limit ray with an angle of α (emitted along the straight line D) and of the straight line parallel to the optical axis and passing through the upper edge of the first reflecting means 22 (this edge being determined by the limit ray with an angle of γ).
Finally, since the image of the surface light source 3 by reflection on the first reflecting means 22 is inclined with respect to the optical axis of the system, the maximum intensity of the beam created by the upper parabolic section is not necessarily located on the horizontal axis: a prism angle δ can be used to angularly offset the beam emerging from the upper band (for example, δ=6°).
Depending on the values of the chosen parameters, the reflection on the parabolic section may be a total internal reflection for all the rays (this is the case in the example considered here). If this is not so, the second reflecting element 24 may be metal-coated. The efficiency may be very slightly diminished in this case.
A second embodiment is described below with reference to
A third embodiment is described below with reference to
The first light rays 302, 303 emitted by the surface light source 3 form a sufficiently large angle with the optical axis 90 in the plane P to prevent them from passing through the central part 42″ of the shaping member 2. Thus these first light rays are emitted toward the upper part 41″ (or the lower part) and enter this part at a surface 28. The first rays are then deflected as they pass through optical surfaces. For example, the ray 302 enters the upper part at the face 28 without being deflected and passes out of the upper part at the optical surface 251 while being deflected by the latter. Similarly, the ray 303 enters the upper part at the face 28 without being deflected and passes out of the upper part at the optical surface 252 while being deflected by the latter.
The second light rays 301 emitted by the source form a sufficiently small angle with the optical axis 90 in the plane P to pass through the central part 42 of the shaping member 2. Thus these second light rays are emitted outside the shaping member 2, at the position of the central part 42″. For this purpose, the second light rays pass through a first optical surface 28 as they enter the shaping member 2, then pass through a second optical surface 27 as they pass out of the shaping member 2. Consequently they pass out of the shaping member 2 at a face 21 formed by the second optical surface 27.
Clearly, with this third embodiment, the viewer does not see three bands of light, but sees nine in the illustrated example, assuming that the lower part is symmetrical to the upper part.
These different embodiments may be combined unless they prove incompatible for technical reasons.
In the different embodiments, the second light rays are rays emitted, in projection on the plane P, in the sector delimited by the straight line D, its mirror image with respect to the optical axis 90, and the surface light source 3, and rays whose extensions only cut the straight line D or its mirror image after the optical surface 27. The projections of the first light rays on the plane P, in the sector, cut the straight line D or its mirror image with respect to the optical axis 90 cut the straight line D or its mirror image before the optical surface 27.
In the different embodiments, the optical device 1 comprises a housing 91 closed by a closing outer lens 92, within which housing the surface light source 3 and the shaping member 2 are located. The shaping member 2 is formed by a transparent one-piece component. The first and second rays pass through the shaping member 2. It is considered that the second rays passing through the central part 42 of the shaping member 2 are not deflected by the shaping member 2. In the described embodiments, this is true only of the light rays emitted from the longitudinal axis of the face 31. This is because a light ray emitted from the upper edge of the face 31 parallel to the optical axis 90 is slightly deflected as it passes through the first optical surface 28, and is then slightly deflected again as it passes through the second optical surface 27.
Preferably, in this document, it is considered that a ray is not deflected by the shaping member 2 if its projection in the plane P is not deflected by more than 5° by this shaping member 2. As a corollary, it is considered that a light ray is not deflected unless its projection in the plane P is deflected by more than 5°.
In the different embodiments, the optical device 1 is a lighting and/or signaling device comprising a housing 91 closed by an outer lens 92. The optical device 1 also has an optical axis 90.
In the different embodiments, the emission area of the surface light source is preferably greater than 1 cm2, or greater than 5 cm2, or greater than 10 cm2.
In the different embodiments, the optical device 1 has elements for positioning and holding the surface light source 3 relative to the shaping member 2. The optical device 1 described above has a constant cross section along the whole of its length. However, it is conceivable that the geometry of its cross section may vary along the optical device 1. It is also conceivable that the optical device 1 may not be rectilinear as shown in the figures, but may have at least one curve.
The surface light source 3 may comprise a plurality of surface light-emitting elements, notably a plurality of organic light-emitting diodes.
The organic light-emitting diode may be of the conformable type. For example, it may be made in the form of a film that can be deposited on a surface, notably on a bent surface. Alternatively, it may be made by a method of printing the different layers, notably by a method of printing on a bent surface.
An organic light-emitting diode device 60 of this type is shown in
The optical device according to the invention can be used, for example, for any of the following functions: signaling the position of the vehicle, signaling a change in direction, signaling reversing, signaling braking, and signaling in case of fog.
If the optical device is inactivated, that is to say if the surface source emits no light, an observer looking at the device face-on sees the light source as if it were present on each of the faces 21 and 25 or 251 to 254. In the case of an organic light-emitting diode, the faces 21 and 25 or 251 to 254 therefore have a metallic appearance.
While the system, apparatus, process and method herein described constitute preferred embodiments of this invention, it is to be understood that the invention is not limited to this precise system, apparatus, process and method, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 11 57800 | Sep 2011 | FR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2012/067068 | 9/3/2012 | WO | 00 | 5/16/2014 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2013/030396 | 3/7/2013 | WO | A |
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