MOTOR VEHICLE LIGHT DEVICE CASING

Abstract

The invention proposes a light device casing formed by a wall made of an electrically insulating material, such as a polymer. The casing includes an inner surface forming a housing receiving a light module with a light-emitting diode and a light guide. The inner surface includes a zone reflecting light from the light module out of the casing, and a fixing zone for a control module of the light module. The light device includes a reflecting and electrically conductive coating, which covers both the reflecting zone and the fixing zone. The aluminum coating is cost-effective since it is applied in one step, and it ensures two functions, namely a reflection and a protection against the electromagnetic field.

Claims

1. Casing for a light device produced in an electrically insulating material and comprising an inner surface forming a housing, the housing being intended to be closed by an outer lens and to receive a light module; the inner surface comprising: a reflecting zone configured to reflect the light emitted by the light module out of the casing, and a fixing zone for a control module of the light module; characterized wherein the inner surface comprises a reflecting and electrically conductive coating covering both the reflecting zone and the fixing zone of the control module in order to block the electromagnetic field produced by the control module.

2. Casing according to claim 1, wherein the coating is metallic and extends over most, preferentially over substantially all, of the inner surface of the casing.

3. Casing according to claim 1, wherein the coating comprises aluminum and the electrically insulating material of the casing is a polymer.

4. Casing according to claim 1, wherein the fixing zone for the control module is bordered by at least two fixing bosses facing one another, the bosses being covered by the coating.

5. Casing according to claim 4, wherein at least one or each boss comprises a shoulder forming a bearing surface for the control module, and a fixing axis protruding from the associated shoulder, each shoulder and each fixing axis being covered by the coating.

6. Casing according to claim 1, wherein the light device comprises an opening, notably a central opening, which is bordered, preferentially surrounded, by the coating.

7. Casing according to claim 1, wherein the reflecting zone forms a longitudinal groove suitable for reflecting light from a longitudinal light guide in a main direction, the coating covering the longitudinal groove.

8. Casing according to claim 1, wherein, in the normal mounting direction, the coating is more backward in the fixing zone than in the reflecting zone.

9. Light device for a vehicle, notably a motor vehicle, the device comprising a casing and an outer lens which delimit a housing, a light module which is arranged in the housing and which comprises a light source and possibly a light guide associated with the light source, wherein the casing is in accordance with claim 1.

10. Light device according to claim 9, wherein the control module comprises a heat sink in contact with the coating.

11. Light device according to claim 10, wherein the light device comprises an electrically conductive washer at the interface between the coating and the heat sink in order to ensure an electrical connection.

12. Light device according to claim 1, wherein the light device comprises an occulting screen between the fixing zone and the light module which intercepts the radiation from the light module, the field occulted by the screen being also covered by the coating.

13. Light device according to claim 1, wherein the control module comprises a printed circuit board connected to the light module and to the coating.

14. Light device according to claim 1, wherein the control module comprises two thickness-wise opposing main faces, the coating closely following substantially all of a main face of the control module.

15. Light device according to claim 1, wherein the light guide extends over most of the length of the light device or substantially all of its length, the coating running along the light guide over substantially all of its length.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] FIG. 1 represents a motor vehicle part with a light device according to the invention.

[0051] FIG. 2 illustrates an open light device according to the invention.

[0052] FIG. 3 shows a cross section of the casing according to the invention following the axis 3-3 drawn in FIG. 2.

[0053] FIG. 4 sketches the contact between a control module and a boss according to the invention.

DESCRIPTION OF THE EMBODIMENTS

[0054] In the following description, the terms front and back are considered in the main direction of emission of the light from the light device, and/or in the main direction of displacement of the associated vehicle.

[0055] FIG. 1 shows a simplified representation of a light device 2 of a motor vehicle. The device 2 can correspond to a front right fog light which is incorporated in the bodywork 4 of a vehicle. It can also be a lighting or signaling device, at the front or equally at the rear of the vehicle. It can be a headlight.

[0056] The light device 2 comprises a casing 6 defining a housing 8, or a free clearance in the manner of a hollow receptacle. This housing 8 can be a main housing 8. It is delimited by the inner surface of the casing by its walls forming a shell. The housing can be closed by an outer lens 10, notably a projection outer lens which offers two diopters. The thicknesses and the curvatures of the outer lens 10 can participate in directing the light emitted by the light device 2 in a main direction. A seal (not represented) can ensure a seal-tightness between the outer lens 10 and the casing 6, possibly by being placed in a perimeter channel of the latter.

[0057] The light device 2 comprises at least one light module, possibly several light modules. Each of them comprises a light source, and possibly a light guide 12 also called waveguide or optical guide. Each light guide 12 is associated with a light source in order to channel and orient the radiation therefrom in a main direction. The light source can be a light-emitting diode (LED). It can alternatively be a laser. A combination of light sources can be considered.

[0058] The material forming the light guide 12 is transparent. Here, it is a material for an optical lens, such as an organic material or possibly glass. It is made of a single piece. The light guide 12 makes it possible to distribute the area of emergence of the light rays over its length. This area can form a strip. To this end, the light guide 12 can comprise a body with a series of streaks distributed over a rear surface. The light guide 12 can be essentially elongate, that is to say that its length is greater than twice, preferably greater than four times, its width.

[0059] A control module makes it possible to manage the power supply for the light source. Its operation generates an electromagnetic field that the present casing 6 precisely makes it possible to intercept so as not to interfere with the rest of the vehicle.

[0060] FIG. 2 shows a simplified representation of a subassembly of the light device. This subassembly comprises the casing 6, the control module 14; and possibly a light module 16 with the light guide 12 and a light source, which can be concealed by a cover 18. The cover 18 can also hide the printed circuits attached to the light source. The outer lens is absent, the housing 8 of the casing 6 is therefore open. A heat sink (not represented) can be coupled to the light source to cool it, this heat sink being advantageously outside of the casing 6.

[0061] The inner surface 20 of the casing 6 has several zones. A first zone 22 runs along the light guide 12, and is reflective in order to return a part of the light from the light guide 12 being propagated backward; in other words opposite the main direction of the light device 2. This first reflecting zone 22 passes through substantially all the length of the casing 6. The inner surface 20 also has a second zone 24 receiving the control module 14. This zone can form a fixing zone 24 for the control module 14 by virtue of the bosses 26 or blocks arranged at the ends of its length. The zone 24 for the control module 14 can form a widening, and/or an extensive zone. In the normal direction of mounting of the casing 6 on the vehicle, the width is measured vertically, and the depth is measured to the rear.

[0062] The control module 14 can generally form a plate. It can include a heat sink 28, for example in the form of a sheet metal. It can also have a printed circuit board with electrical components making it possible to adapt the electrical current of the vehicle to the functions that the light source has to provide. The electrical components are advantageously arranged toward the bottom of the casing 6. The board covers a smaller area than the sink 28.

[0063] The device 2 can be of the type with a longitudinal light guide 12. The latter can generally pass horizontally through the casing 6, and/or cover half the length of the casing 6. Length is understood to be in accordance with the main elongation of the casing 6.

[0064] The casing 6 can be produced in an electrically insulating material. It can be made of ceramic, or of polymer. It can comprise polypropylene, or polyamide. Other materials can be considered. The abovementioned materials provide a trade-off between the cost, the weight and the mechanical strength of the casing 6. The insulating material can be employed to form the walls (30; 31) of the casing, and notably the inner surface 20 defining the housing 8.

[0065] In order to avoid the electromagnetic field produced by the control module 14 being propagated to the interior of the vehicle, the casing 6 comprises an electrically conductive coating 32 which is also reflective. The latter is applied to the inner surface 20 of the casing 6, i.e. on and in contact with the insulating material. The coating 32 covers the reflecting zone 22 to return the radiations, and covers the fixing zone 24 to create an electromagnetic protection. The coating 32 can be uniform, of the same composition over its entire surface. It is linked to the ground of the vehicle in which the light device 2 is mounted, so that the electromagnetic waves are intercepted and are not propagated through the vehicle. In this way, the equipment items in the vehicle are not subjected to the electromagnetic interferences produced by the control module 14.

[0066] The coating 32 lines the inner surface 20 at the control module 14, in the zone 24 where the latter is fixed. Here, the coating 32 can also be reflective. The coating 32 can reach the opposite edges of the casing, for example the longitudinally opposite edges. It can coat most of the inner surface 20 of the casing 6, possibly substantially all. It covers both the bottom wall 31 of the casing 6, and each perimeter wall 30 which surrounds the bottom wall 31.

[0067] The coating 32 can comprise a conductive material which is applied in the form of a film to the interior of the casing. It is a surface deposition. The application can be performed in vapor phase of CVD (chemical vapor deposition) type, or by spraying. Other methods can be considered. The coating 32 can comprise a metal; for example aluminum, tin, or steel to guarantee optimal reflection. The electrical resistivity of the coating is less than or equal to 1000 10̂(−9) Ω*m, preferentially less than or equal to 100 10̂(−9) Ω*m, more preferentially less than or equal to 28 10̂(−9) Ω*m; possibly greater than or equal to 25 10̂(−9) Ω*m.

[0068] The casing 6 can have an opening 34 for the passage of power supply cables 36 connected to the electrical circuit of the vehicle. The opening 34 can generally be arranged in a central position to facilitate access thereto from the interior of the vehicle. The opening 34 can be circled by the coating 32. The light module 16 is powered from the control module 14 via auxiliary cables 37. They are held by virtue of fork-shaped guides 38. The guides 38 are also covered by the coating 32. The perimeter channel 40 of the casing 6, notably its bottom, and/or the cover 18, can be covered by the coating 32.

[0069] FIG. 3 is a view in cross section of the casing 6 on the axis 3-3 drawn in FIG. 2. The light guide 12 and one of the bosses 26 supporting the control module 14 are represented.

[0070] The light guide 12 is arranged in the reflecting zone 22. It is placed in front of the longitudinal groove 42. The latter can show a profiled form, possibly with a profile in the form of a parabola. The light guide 12 can be arranged at the focal point of the parabola. The light guide 12 can be arranged at the focal point of the parabola in order to favor a return of the radiation from the light guide 12 in a predetermined direction, for example in the main direction 44 of light emission of the device 2.

[0071] The control module 14 is placed toward the rear of the light guide 12. One of its main faces is facing the rear part of the reflecting zone 22, that is to say the bottom wall 31. The corresponding surface can be followed in order to better block the electromagnetic waves 46 emitted by the control printed circuit board 48. The control module 14 is rigidly linked to the casing 6, the link being made by virtue of the bosses 26. These are also covered by the coating 32 so that the casing 6 is tight to the electromagnetic waves 46; so that no breach remains.

[0072] A part of wall (30; 31) can cover the light guide 12 so as to form an occulting screen with respect to another part of wall. This screen conceals an area of the fixing zone 24. It can also be concealed by the control module 14 itself. The occulted area does not receive direct radiation from the light module 16. The occulted area is also covered by the coating 32, partially or totally.

[0073] FIG. 4 represents a link between a boss 26 and the control module 14. An electrically insulating portion of wall, in this case the bottom wall 31, is also represented. Although just one link is represented, the present teaching can be applied to each link of this type.

[0074] At least one or each boss 26 can comprise a fixing axis 50 and a shoulder 52 against which the control module 14 rests. The latter can also comprise fixing orifices in which the fixing axes 50 are linked. The shoulders 52 can be coplanar to allow a surface-to-surface bearing of a face of the control module 15, in this case a face of the heat sink 28.

[0075] The boss 26 is covered by the coating 32, in particular its shoulder 52 and/or its fixing axis 50. This allows an electrical contact between the control module 14 and the coating 32 which is itself linked to the ground of the vehicle. The printed circuit board 48 is also connected electrically to the heat sink 28 by virtue of an electrical terminal 54 which crosses the printed circuit board 48. In this way, the latter is also linked to the ground of the vehicle, which simplifies the electrical connections, and which can possibly save on a cable.

[0076] In order to improve the electrical contact, a conductive washer 56, for example made of aluminum, is threaded around the fixing axis 50. The washer 56 is in contact with the coating 32 and the heat sink 28. The presence of the washer is not essential since the heat sink can be directly in contact with the boss, whether it is the axis or the shoulder.