CN110296374B

CN110296374B - Illumination module equipped with a micromirror matrix with optimized cooling

Info

Publication number: CN110296374B
Application number: CN201910225394.3A
Authority: CN
Inventors: 马克西姆·卢梭; 托马斯·丹尼尔
Original assignee: Valeo Vision SAS
Current assignee: Valeo Vision SAS
Priority date: 2018-03-23
Filing date: 2019-03-22
Publication date: 2022-10-28
Anticipated expiration: 2039-03-22
Also published as: FR3079283B1; CN110296374A; EP3543597B1; FR3079283A1; EP3543597A1

Abstract

A lighting module (3) for a headlamp (2) of a motor vehicle (1), comprising: -a first area (Z1) comprising at least one light source (22') and a matrix of micromirrors (24); -a second zone (Z2) comprising a first heat sink (26) for dissipating heat generated by the light source (22'); -a third region (Z3) comprising a second heat sink (27) for dissipating heat generated by said micromirror matrix (24); -at least one air flow generating device (31 ', 32') for generating an air flow in a first zone (Z1), a second zone (Z2) and a third zone (Z3), the first zone (Z1), the second zone (Z2) and the third zone (Z3) being different from each other, the first zone (Z1) being arranged vertically between the second zone (Z2) and the third zone (Z3), the first zone (Z1) comprising an air outlet (30).

Description

Illumination module equipped with a micromirror matrix with optimized cooling

Technical Field

The invention relates to an illumination module for a headlight of a motor vehicle, comprising a micromirror matrix. The invention also relates to a headlamp for a motor vehicle comprising such a lighting module. The invention also relates to a motor vehicle comprising such a headlamp or such a lighting module.

Background

For the illumination of motor vehicles, it is known to use an illumination module comprising a light source and a matrix of micromirrors. A micromirror matrix is an electromechanical microsystem that includes a plurality of micromirrors that all move about the same axis and can assume at least two different orientations. According to its first orientation, the micromirror transmits light out of the illumination module in an illumination field. According to its second orientation, the light rays deviate from the illumination field and are absorbed by the structure of the illumination module. The orientation of each micromirror can be individually controlled by the action of electrostatic forces. The lighting module comprises a control circuit connected to the electronic control unit. An electronic control unit emits control currents to each micromirror to define their orientation.

Such a headlamp makes it possible to construct and project a complex image in front of the vehicle. The headlights are therefore used to produce different functions, such as the projection of information useful for the safety of pedestrians directly around the vehicle, or again, for example, a road lighting function to avoid dazzling other drivers.

In its operation, such a lighting module may be heated considerably. Excessive heating can cause malfunction or even destruction of the micromirror matrix or its control circuitry. In order to cool the micromirror matrix, it is known to use a heat sink associated with a fan. However, these cooling means are not sufficient to keep the lighting module below damaging temperatures.

Disclosure of Invention

It is an object of the present invention to provide a lighting module which remedies the above disadvantages and improves the lighting modules known in the prior art. In particular, the invention makes it possible to manufacture a lighting module that is compact, easy to implement and limits the heating of the light source, the micromirror matrix and its corresponding control circuitry.

The invention relates to a lighting module for a headlight of a motor vehicle, comprising:

-a first area comprising at least one light source and a matrix of micromirrors;

-a second region comprising a first heat sink that can dissipate heat generated by the at least one light source;

-a third region comprising a second heat sink that can dissipate heat generated by the micromirror matrix;

at least one air flow generating device for generating an air flow in the first zone, the second zone and the third zone,

the first, second and third zones are different from each other, the first zone being vertically arranged between the second and third zones, the first zone comprising an air outlet.

The air outlet of the first region may be oriented upwardly through the top surface of the lighting module. As a variant, the air outlet may be oriented downwards, or to the side, or to the rear of the lighting module.

The air outlet may comprise at least one vent through the second region, in particular two vents through the second region on both sides of the first heat sink.

The at least one vent may be vertically oriented and may be angled toward a rear of the lighting module.

The second region may be disposed above the first region. The third region may be disposed below the first region.

The first area may be at least partially delimited from the second area by a base of the first circuit board and/or the first heat sink supporting the at least one light source. The first region may be at least partially bounded by a second circuit board supporting the micro mirror matrix and/or a base of a second heat sink with the third region.

The illumination module may include projection optics capable of directing light reflected by the micro-mirror matrix, the first region, and/or the second region, the second region including an air outlet above the projection optics.

The second and/or third zones may comprise air outlets towards the front.

The first area and/or the second area and/or the third area may comprise an air inlet from the rear.

The air flow generating means may comprise at least one fan, in particular at least two fans.

The lighting module may include a first fan capable of generating airflow only in the first and third regions and a second fan capable of generating airflow only in the second region.

The two fans may be arranged in parallel up and down.

The at least one light source may comprise at least one light emitting diode.

The invention also relates to a headlamp comprising a lighting module as defined above.

The invention also relates to a motor vehicle comprising a lighting module as defined above or a headlamp as defined above.

Drawings

These objects, features and advantages of the present invention will be illustrated in detail in the following description of specific embodiments thereof, given in non-limiting manner in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic illustration of a motor vehicle according to an embodiment of the present invention;

fig. 2 is an upper isometric view of a lighting module according to an embodiment of the invention;

fig. 3 is a front isometric view of a lighting module according to an embodiment of the invention;

fig. 4 is a schematic cross-sectional view of an outline of a lighting module according to an embodiment of the invention;

fig. 5 is a cross-sectional isometric view of a lighting module according to an embodiment of the present invention;

fig. 6 is a rear isometric view of a lighting module according to an embodiment of the invention;

fig. 7 is an isometric view of a lighting module without its protective housing according to an embodiment of the present invention;

FIG. 8 is an upper isometric view of a first heat sink according to an embodiment of the invention;

figure 9 is a lower isometric view of a second heat sink according to an embodiment of the invention.

Detailed Description

Throughout the drawings and description, left and right are defined according to the viewpoint of the vehicle driver. Axis X represents the longitudinal axis of the vehicle. Forward and in a straight line, the vehicle advances from the rear to the front in a direction parallel to its longitudinal axis. The axis X is oriented from the front to the rear of the vehicle, that is to say in the retrograde direction. Axis Y represents the transverse axis of the vehicle. Axis Y is oriented from left to right. Axis Z represents an axis at right angles to axis X and axis Y. The axis Z is a vertical axis when the vehicle is standing on a level ground. Axis Z is oriented from bottom to top. The axes X, Y and Z form a direct orthogonal reference frame. Throughout the drawings and description, the vehicle is considered to stand on a level ground. Moreover, for the sake of simplifying the description, this same reference frame defined by reference to the vehicle will be used for the lighting module even when considering the outside of the vehicle, since it is intended to be mounted on the vehicle according to a specific orientation.

Fig. 1 shows a motor vehicle 1 provided with a headlamp 2 according to an embodiment of the invention. The vehicle may be of any type, for example it may be a private vehicle, a utility vehicle or a truck. The headlight 2 is arranged in the front of the vehicle, but may equally be mounted in the rear of the vehicle. The headlamps enable illumination of the road, viewing by other drivers, and/or projection onto ground images to provide information to the driver or his or her environment. The headlamp 2 comprises a lighting module 3 according to an embodiment of the invention.

Fig. 2 and 3 show a lighting module 3. The lighting module 3 comprises a housing 10, which housing 10 forms a protective sleeve in the form of an integral parallelepiped. The lighting module 3 also comprises various electrical connectors 4, which electrical connectors 4 make it possible to electrically connect the lighting module to an electronic control unit embedded in the vehicle. There can be any number of these connectors and these can be of any form.

The illumination module 3 comprises projection optics 21 oriented towards the front, through which projection optics 21 light rays can be emitted. The housing 10 comprises a first front end aperture 11, which first front end aperture 11 is located above the projection optics 21, is intended for an outlet for a gas flow, is oriented substantially parallel to the longitudinal axis. The first front end aperture has an overall rectangular form with the long side of the rectangle parallel to the transverse axis. The housing 10 further comprises a second front end aperture 12, which second front end aperture 12 is located below the projection optics 21, also intended for the outlet of the gas flow, substantially longitudinally oriented. This second front end aperture 12 is visible in particular in fig. 3: which in practice comprises five windows positioned transversely to each other. Finally, the housing also comprises two top apertures 13 on the top of the housing 10, which top apertures 13 are also intended for the outlet of the gas flow. The form of these different apertures may be different, as long as they allow air to pass between the interior and exterior of the housing 10, in accordance with the operations described in detail below.

Referring to fig. 4 and 5, the lighting module 3 includes three zones Z1, Z2, Z3 different from each other. These three regions correspond to complementary volumes of the lighting module. The first zone Z1 comprises on the one hand a light emitting diode 22 connected to a first circuit board 23 and on the other hand a micro mirror matrix 24 connected to a second circuit board 25. The two

circuit boards

23, 25 may comprise drivers or electronic components such that the switching on of the light emitting diodes 22 and the activation of the micromirror matrix 24 may be controlled separately. The first zone Z1 also comprises projection optics 21. The first region is thus a generation site where light and light are diffused out of the headlamp. The second zone Z2 comprises a first heat sink 26 capable of dissipating heat generated by the light emitting diodes. The third region Z3 includes a second heat sink 27 capable of dissipating heat generated by the micromirror matrix 12. With reference to the vertical axis, the second zone Z2 is arranged above the first zone Z1, and the third zone Z3 is arranged below the first zone Z1. Thus, the first region is arranged between the second region Z2 and the third region Z3 in the vertical direction.

The first zone Z1 comprises an air outlet 30, which air outlet 30 is directed upwards via the top surface of the lighting module and coincides with the top aperture 13 of the housing. The second zone Z2 comprises an air outlet 34, which air outlet 34 is oriented towards the front of the lighting module and coincides with the first front end aperture 11 of the housing. The third zone Z3 comprises an air outlet 35, which air outlet 35 is oriented towards the front of the lighting module and coincides with the second front end aperture 12 of the housing. As mentioned above, these regions are different and their respective air outlets are different.

The first zone Z1 is delimited from the second zone Z2 along a first plane in which the first circuit board 23 extends. The first plane is inclined forwardly and upwardly relative to the horizontal as shown in fig. 4 and 5. The first region Z1 is delimited from the third region Z3 along a second plane in which the second circuit board 25 extends. The second plane is substantially horizontal. Thus, the first zone Z1 comprises a cross section in the form of an overall trapezoid. The small base of the trapezoid is located at the rear side of the lighting module and the large base of the trapezoid is located at the front side.

The light emitting diode 22 is a light source 22'. As a variant, the light emitting diodes may be replaced by any other form of light source, such as incandescent lamps. The lighting module may comprise any number of light emitting diodes or any other form of light source.

The illumination module 3 comprises a collimating lens 28 and an optical prism 29, both of which are located in the first zone Z1. A collimating lens 28 and an optical prism 29 are sandwiched between the light emitting diode 22 and the micromirror matrix 24 to form and direct a light beam toward the micromirror matrix 24. The projection optics 21 is located downstream of the micromirror matrix 24 and comprises several lenses in series.

The micromirror matrix 24 is an electromechanical microsystem that includes a plurality of planar micromirrors that are all independently movable about the same axis. The micromirrors can assume two different orientations. The orientation of each micromirror can be individually controlled by the action of electrostatic forces. The micro mirror matrix has a rectangular form, and may include hundreds of micro mirrors in its width and hundreds of micro mirrors in its length. According to a first orientation, referred to as the active orientation, the micro-mirrors reflect light generated from the light emitting diodes towards the projection optics 21. According to a second orientation, referred to as the inactive orientation, the micro-mirrors do not reflect light generated from the light emitting diodes towards the projection optics. The micromirror matrix receives commands that define which micromirrors are oriented according to a first orientation and which micromirrors are oriented according to a second orientation. Thus, each micromirror defines a pixel of an image: the micromirror matrix can be used not only to obtain standardized illumination but also to project complex images. The micromirror matrix is incorporated in a chip of larger size. The chip is incorporated in the second circuit board 25. To ensure proper operation, the temperature of the chip and micromirror matrix should not exceed a threshold temperature.

The first heat sink 26 and the second heat sink 27 are means for dissipating heat by thermal conduction. Each heat sink is preferably made of a thermally conductive material (e.g., aluminum or copper) in the form of only a single component. The heat sink preferably comprises as large an air exchange surface as possible.

The first heat sink 26 is visible in particular in fig. 7 and 8. The first heat sink includes a base portion 26A that is pressed against the first circuit board 23. The base portion 26A has an overall rectangular form and has a surface larger than that of the first circuit board 23. In addition to the first circuit board, the base 26A may physically separate the first zone Z1 from the second zone Z2. The first heat sink 26 also includes a set of integral vertically upwardly extending posts 26B. The posts 26B form a grid in the form of a rectangular exterior having a first side extending parallel to the longitudinal axis X and a second side extending parallel to the transverse axis Y. The set of columns 26B is surrounded left and right by two lateral wings 26C extending longitudinally and vertically.

The second heat sink 27, which is visible in particular in fig. 9, is in contact with the second circuit board 25. The second heat sink includes a base portion 27A extending parallel to the second circuit board 25. The second heat sink further includes a main body 27D in the form of an integral parallelepiped and extending upward from the top surface of the base 27A. The body is pressed against the chip containing the micromirror matrix 24 so as to conduct heat generated by the micromirror matrix 24 into all of the second heat sink 27. The second heat sink 27 also includes a set of posts 27B, which posts 27B extend generally vertically downward from the base 27A. The posts 27B form a grid in the form of a rectangular exterior with a first side extending parallel to the longitudinal axis X and a second side extending parallel to the transverse axis Y. The set of columns 27B is surrounded left and right by two lateral wings 27C extending longitudinally and vertically.

There may be any number of

posts

26B, 27B. As a variant, the posts may be replaced by fins oriented parallel to the air flow intended to pass through the radiator, that is to say parallel to the longitudinal axis X.

Two

vents

30A, 30B are disposed on either side of the first heat sink 26. These two ventilation openings make it possible to connect the first zone Z1 with the outside of the lighting module. Thus, the two ventilation openings constitute the air outlet 30 of the first zone Z1. Two ventilation openings pass through the second zone Z2 on both sides of the first heat sink 26. The two vents extend vertically and are substantially inclined towards the rear of the lighting module. In other words, the axes of the

vents

30A, 30B form a non-zero angle with the vertical axis. On the one hand, two ventilation openings are formed in the first zone Z1 at the high points of the first zone, that is to say on the side of the large base of the trapezoid forming the cross section of the first zone Z1, at the level of the separation plane between the first zone and the second zone. On the other hand, two

vents

30A, 30B are formed facing the two top holes 13 of the housing 10. The vent has an elliptical cross-section but could, as a variant, have any other form of cross-section. As a variant, the number of these vents may also be different. The lighting module may include only a single vent or more than two vents. Advantageously, the two vents and the first heat sink form one and the same component.

Referring to fig. 6, the lighting module 3 further comprises two

fans

31, 32 arranged at the rear of the lighting module and capable of generating an air flow in each of the three zones Z1, Z2 and Z3. More specifically, the first fan 31 is arranged to generate an air flow only in the first zone Z1 and the third zone Z3, and the second fan 32 is arranged to generate an air flow only in the second zone Z2. Thus, the first heat sink 26 associated with the light emitting diodes 22 benefits from a dedicated fan which allows particularly efficient cooling of the light emitting diodes. The two

fans

31, 32 are arranged vertically up and down. Advantageously, the two fans may be identical or at least have substantially identical external forms. They each comprise at least one

rotary blade

31A, 32A and an electric motor capable of driving the blades in rotation. The lighting module comprises an air inlet 33 at the rear of each fan, through which air inlet 33 fresh air can be drawn into the lighting module. As a variant, each fan may be replaced by any other air flow generating means 31', 32'. In particular, two fans may be replaced by one stronger fan.

When the fan is operating, the airflow in each zone Z1, Z2, and Z3 is oriented substantially longitudinally from back to front. The airflow through the three zones Z1, Z2, Z3 is independent. The gas flows do not mix. However, the three zones Z1, Z2, Z3 do not necessarily need to be completely sealed from one another, but rather there may be air leaks between the zones as long as these leaks are kept to a minimum as compared to the airflow through each zone.

The airflow in the first zone Z1 is indicated by a first arrow F1 in fig. 4 and 7. The airflow in the first zone Z1 is generated by the first fan and is guided between the first circuit board and the second circuit board. The airflow convectively cools the light emitting diodes 22 and the micromirror matrix 24, and then exits upward through two

vents

30A, 30B connected to the two top holes 13 of the housing. Note that, since the two vents extend from the topmost part of the first zone Z1, even when the first fan is not operating, hot air lighter than cold air will tend to be discharged from the first zone through the two vents. Warm air, which is lighter than cold air, will tend to naturally exit through the two vents to leave space for cooler air to enter through the air inlet 33 at the rear of the lighting module. Therefore, the structure of the first zone Z1 facilitates minimal natural cooling of the first zone Z1. This phenomenon is added to the contribution of the first fan 31 to optimize cooling.

The air flow in the second zone Z2, represented by the second arrow F2 in fig. 4 and 7, passes through the first radiator and is emitted from the headlamp through the first front end aperture 11 of the casing 10. Fresh air drawn in by the first fan passes through the first radiator, sliding around the post 26B. The airflow in the second region is directed laterally between the two wings 26C, the base 26A and the top side of the housing 10. Heat is exchanged between the fresh air and the warmer radiator. This heat exchange helps to reduce the temperature of the first heat sink 26 and thus the first circuit board 23 and the light emitting diodes 22.

The air flow in the third zone Z3, represented by the third arrow F3 in fig. 4 and 7, passes through the second radiator 27 and exits the headlamp through the second front end aperture 12 of the casing 10. A first part of the airflow in the third region Z3 circulates between the second circuit board 25 and the base 27A of the second heat sink 27. The second part of the air flow in the third zone Z3 passes through the second heat sink 27, sliding around its post 27B. The second part is guided between the side wings 27C, the base 27A and the bottom side of the housing 10. Heat is exchanged between the fresh air and the warmer radiator. This heat exchange helps to reduce the temperature of the second heat sink 27 and thus the second circuit board 25 and the micromirror matrix 24. The airflow is emitted from the third zone Z3 through the second front opening 12 of the housing.

When the light emitting diodes emit light, the light first passes through the collimating lens 28 and then through the optical prism 29 before reaching the micromirror matrix 24. If the light reaches the actively oriented micromirror, it is reflected towards the optical prism 29, from which optical prism 29 the light will be deflected towards the projection optics 21. The light then passes through the different lenses forming the projection optics and is thus emitted forward from the headlamp to illuminate the road or the environment of the vehicle. Such a path is indicated by the dashed line R1 in fig. 4. If the light reaches the micromirror in the inactive orientation, it is deflected away from the projection optics 21 and does not participate in the illumination of the road or vehicle environment. If stray light exits the lighting module through one of the

vents

30A, 30B, for example along the path shown by line R2 in fig. 4, it also does not participate in the illumination of the road or vehicle environment because the vent is tilted backwards. Thus, the backward inclination of the vents avoids light that may be emitted in a stray manner from the lighting module through the

vents

30A, 30B from being visible.

Of course, the invention is not limited to the described embodiments. In particular, as a variant, the air outlet 30 of the first zone Z1 (which may be in the form of one or

more ventilation openings

30A, 30B) may not be formed upwards but on the right and/or left side or downwards, even towards the rear of the lighting module 3. Advantageously, in all cases, the air outlet is advantageously substantially inclined towards the rear, so as to avoid stray light being visible in front of the vehicle by passing through the air outlet.

By means of the invention, an illumination module is obtained in which the air flow is circulated not only around the heat sink but also around the light source 22' and the micromirror matrix. The gas flows are independent, which makes it possible to obtain a particularly efficient cooling. The temperature of the light source can be reduced by about 10 c and the temperature of the micromirror matrix can be reduced by about 5 c compared to known lamp modules, thereby improving the lifetime and reliability of these components.

Claims

1. A lighting module (3) for a headlamp (2) of a motor vehicle (1), characterized in that it comprises:

-a first area (Z1) comprising at least one light source (22') and a matrix of micromirrors (24);

-a second zone (Z2) comprising a first heat sink (26) capable of dissipating heat generated by the at least one light source (22');

-a third region (Z3) comprising a second heat sink (27) capable of dissipating heat generated by the micromirror matrix (24);

-at least one gas flow generating device (31 ', 32') for generating a gas flow in the first zone (Z1), the second zone (Z2) and the third zone (Z3),

the first zone (Z1), the second zone (Z2) and the third zone (Z3) being different from each other, the first zone (Z1) being arranged vertically between the second zone (Z2) and the third zone (Z3), the first zone (Z1) comprising an air outlet (30),

wherein the lighting module comprises a first fan (31) capable of generating an air flow only in the first zone (Z1) and the third zone (Z3) and a second fan (32) capable of generating an air flow only in the second zone (Z2).

2. The lighting module (3) according to claim 1, characterized in that the air outlet (30) of the first region (Z1) is oriented upwardly via a top surface of the lighting module.

3. The lighting module (3) according to claim 1 or 2, characterized in that the air outlet (30) comprises at least one ventilation opening (30A, 30B) through the second zone (Z2).

4. A lighting module (3) according to claim 3, characterized in that two ventilation openings (30A, 30B) pass through the second zone (Z2) on both sides of the first heat sink (26).

5. The lighting module (3) according to claim 4, characterized in that the at least one ventilation opening (30A, 30B) is vertically oriented and inclined towards the rear of the lighting module (3).

6. The lighting module (3) according to claim 1 or 2, characterized in that the air outlet (30) of the first zone (Z1) is inclined towards the rear of the lighting module (3).

7. The lighting module (3) according to claim 1 or 2, characterized in that the second zone (Z2) is arranged above the first zone (Z1) and the third zone (Z3) is arranged below the first zone (Z1).

8. The lighting module (3) according to claim 1 or 2, characterized in that the first zone (Z1) is delimited from the second zone (Z2) at least in part by a first circuit board (23) supporting the at least one light source (22') and/or by a base (26 a) of the first heat sink (26), and/or

Characterized in that said first zone (Z1) is delimited from said third zone (Z3) at least in part by a second circuit board (25) supporting said micromirror matrix (24) and/or by a base (27 a) of said second heat sink (27).

9. The illumination module (3) according to claim 1 or 2, characterized in that it comprises projection optics (21) capable of guiding light rays reflected by the micro mirror matrix (24), the first region (Z1) and/or the second region (Z2), the second region (Z2) comprising an air outlet above the projection optics.

10. The lighting module (3) according to claim 1 or 2, characterized in that the second region (Z2) and/or the third region (Z3) comprises an air outlet (34, 35) facing the front.

11. The lighting module (3) according to claim 1 or 2, characterized in that the first zone (Z1) and/or the second zone (Z2) and/or the third zone (Z3) comprise air inlets (33) from the rear.

12. A lighting module (3) according to claim 1, characterized in that two fans (31, 32) are arranged in parallel up and down.

13. The lighting module (3) according to claim 12, characterized in that the at least one light source (22') comprises at least one light emitting diode (22).

14. A headlamp (2) comprising a lighting module (3) according to any of claims 1 to 13.

15. A motor vehicle (1), characterized in that it comprises a lighting module (3) according to any one of claims 1 to 13 or a headlamp (2) according to claim 14.