FR3102829A1 - OPTICAL DEVICE FOR MOTOR VEHICLES - Google Patents

Abstract

The present invention relates to a light module (1) for a motor vehicle comprising: a. a matrix (10) of light sources (11), the light sources (11) emitting light rays in a common direction of emission (X), when supplied with electricity; b. a liquid crystal display (30); vs. an optical part (20) placed opposite the light sources (11) along said common emission direction (X) and receiving light rays emitted by the light sources (11), and transmitting them to the liquid crystal screen ( 30) according to said common emission direction (X), the optical part (20) comprising a plurality of optical elements (21). (Fig. 1)

Description

OPTICAL DEVICE FOR MOTOR VEHICLE

The invention relates to a luminous device for a motor vehicle, in particular an information display device.

Such devices make it possible, when installed on a vehicle, to transmit information to other road users, in the form of pictograms or written messages. Thanks to these devices, it is thus possible to warn the driver of a following vehicle that a dangerous situation of which he is not aware is present. Such a situation can, for example, arise when a pedestrian crosses the road just in front of the first vehicle, while being hidden by the latter from the driver of the following vehicle. The display of a pictogram representing the situation, for example a pictogram representing a pedestrian, on the device of the first vehicle, allows the driver of the following vehicle to become aware of the situation, and thus to anticipate urgent action. , in the case mentioned the risk of sudden braking. Other pictograms, adapted to other dangerous situations, or passenger welcome pictograms (“welcome scenario” in English) near the vehicle, or polite messages are also possible.

It is known, to perform such functions, to use liquid crystal display devices LCD (for "Liquid Crystal Display" in English). They include a liquid crystal display illuminated from behind by a luminous device. To ensure good legibility of the pictograms and/or messages displayed, it is important that the rear lighting has good homogeneity.

There are devices, operating by indirect lighting, providing this characteristic of homogeneity. They comprise light sources arranged to illuminate along an axis substantially parallel to the surface of the liquid crystal screen, and a reflecting and/or diffusing surface making it possible to direct the light rays emitted by the light sources in the direction of the liquid crystal display.

However, these devices have several drawbacks. Due to the operation by indirect lighting, their light output is low. Thus, to generate sufficient luminance for the operation of the display device, it is necessary either to use a large number of light sources, or to use high-power light sources. This increases the cost of the device. This also has the effect of inducing high electrical consumption and generating significant heating. In addition, if the thickness of such a device is reduced, its lateral bulk is significant, due to the fact that the sources must be arranged beyond the lateral perimeter of the liquid crystal screen. However, it is important, for installation on a motor vehicle, to have a small lateral bulk.

The invention proposes for this purpose an information display device for a motor vehicle making it possible to at least partially overcome the drawbacks mentioned above.

1. une matrice de sources lumineuses, les sources lumineuses émettant des rayons lumineux selon une direction d’émission commune, lorsqu'elles sont alimentées en électricité ;
2. un écran à cristaux liquides ;
3. une pièce optique placée en regard des sources lumineuses selon ladite direction d’émission commune et recevant des rayons lumineux émis par les sources lumineuses, et les transmettant vers l’écran à cristaux liquides selon cette dite direction d’émission commune, la pièce optique comportant une pluralité d’éléments optiques.

In this respect, the invention relates to a light module for a motor vehicle comprising:

1. a matrix of light sources, the light sources emitting light rays in a common emission direction, when they are supplied with electricity;
2. a liquid crystal display;
3. an optical part placed facing the light sources in said common emission direction and receiving light rays emitted by the light sources, and transmitting them to the liquid crystal screen in this said common emission direction, the optical part comprising a plurality of optical elements.

The display device according to the invention has good photometric efficiency, which makes it possible to reduce electrical consumption and heating, while guaranteeing high luminance upstream of the LCD screen. The limited heating allows the use of inexpensive materials with limited heat resistance. The good photometric efficiency also makes it possible to reduce the number of light sources used. These characteristics thus make it possible to ensure a low cost of the device. It makes it possible to display pictograms with a good level of homogeneity. It has a small lateral and in-depth encumbrance. In addition, it has good resistance to shocks and vibrations.

According to other characteristics that can be taken alone or in combination:

- at least one optical element is a reflector;

- at least one optical element is a collimator;

- all the optical elements are collimators;

- the optical elements have identical or similar dimensions;

- the optical elements are arranged according to a matrix of optical elements, in correspondence with the matrix of light sources. By the expression "in correspondence" it should be understood that the two dies have the same dimensions and the same pitches;

- the matrix of optical elements is aligned with the matrix of light sources;

- the matrix of optical elements and the matrix of light sources are flat;

- each optical element comprises a light input face opposite which a light source is arranged;

- the optical part is in one piece;

- The optical elements of the optical part are made in one piece;

- The optical elements of the optical part form between them intersections in the form of squares;

- the optical elements of the optical part form between them intersections in the form of hexagons;

- the light entry face of at least one collimator has the shape of a hollow cylinder open at one of its ends, and closed by a curved face at the other end;

- several optical elements are collimators;

- each light source opposite a collimator is located inside the hollow cylinder, on the side of the end where it is open. ;

- each collimator has a light exit face through which the light leaves the light module;

- the output face has a plane carrier;

- the output face comprises optical patterns;

- the exit faces of each collimator are aligned according to an exit plane;

- the liquid crystal screen is parallel to the exit plane;

- the distance between the liquid crystal screen is parallel to the exit plane is between 20 and 30mm, in particular is equal to 25mm;

- each light source comprises a semiconductor emitter;

- each light source comprises at least two semiconductor emitters;

- two of the semiconductor emitters emit different colors;

- each light source comprises at least three semiconductor emitters;

- three of the semiconductor emitters emit different colors;

- the colors are red, green and blue;

- The light sources are arranged on a common support;

- the support is flat;

- the support is light in color, in particular white in color;

- the support is parallel to the liquid crystal screen;

- the light module also comprises a covering element which forms a mechanical connection between the support and the liquid crystal screen, and which surrounds the light sources and the optical element;

- the trim element has a light-coloured interior face, in particular white.

Throughout the application, a light color characterizes a material whose albedo, that is to say the overall reflective power, is greater than 50%, preferably greater than 70%.

1. un boîtier ;
2. un module lumineux selon l’invention ;

le module lumineux étant disposé à l’intérieur du boîtier.The invention also relates to a lighting device for a motor vehicle comprising:

1. a housing ;
2. a light module according to the invention;

the light module being disposed inside the housing.

The invention also relates to a motor vehicle comprising at least one light device according to the invention.

The objects, characteristics and advantages of the present invention will be explained in detail in the following description of several particular embodiments, given without limitation, in relation to the appended figures, among which:

shows a light module according to the invention, seen in perspective.

shows a detail view of the optical part of the light module according to a first embodiment.

shows a sectional view of the optical part of FIG. 2a.

shows a detail view of the optical part of the light module according to a second embodiment.

shows a sectional view of the optical part of FIG. 3a.

shows a perspective view of the light module according to the invention including a covering element.

shows a sectional view of the light module of Figure 4a.

Figure 1 shows in perspective a light module 1 according to the invention. It comprises light sources 11 arranged on a support 15. The light sources 11 are arranged in a matrix 10, that is to say in at least two rows and at least two columns. The pitch of the matrix, i.e. the distance between two adjacent light sources along a row or along a column is constant. In other words, the step of the matrix is identical whatever the two adjacent sources considered. Alternatively, the matrix pitch may be different depending on whether it is taken along a row or a column. Alternatively again, the step of the matrix can vary along a given row or a given column.

The support 15 is common to all the light sources 11. Advantageously this support forms a plane. Thus, the matrix 10, according to which the light sources 11 are arranged, is also planar. According to an alternative embodiment, the light sources 11 are distributed over two different supports 15, or more than two supports 15. In this case, the light sources 11 can each be placed on a support 15 which is specific to it.

The light sources 11 emit light rays in a common emission direction X, when they are supplied with electricity. By common direction of emission it is understood, throughout the application, that each light source has a main axis of emission of light rays around which it emits a beam of light rays, and that said main axes of emission have the same direction.

The optical module further comprises an optical part 20, placed opposite the light sources 11 in the common emission direction X, and a liquid crystal screen 30 placed opposite the optical part 20. When the light sources 11 are powered in electricity they emit light rays which impact the optical part 20. The optical part transmits at least a part of the light rays, according to the common direction of emission X, towards the liquid crystal screen 30. The optical part is connected to the support 15, for example by pins or legs.

The liquid crystal display 30 plays the role of a matrix of optical switches. It can be associated with a control device (not shown), able to individually control each optical switch so that it allows the light to pass or, on the contrary, interrupts its path, respectively defining an on or off pixel. Thus, by choosing the pixels on and off, it is possible to display a pictogram corresponding to the desired message.

The optical part 20 comprises a plurality of optical elements 21 in the form of collimators formed in a transparent material, for example a plastic material such as PMMA (polymethyl methacrylate), PC (polycarbonate) or glass. The material is advantageously devoid of tint. This characteristic makes it possible to guarantee excellent transmission of the light rays. Alternatively, the material can be tinted. This characteristic has the advantage of giving a predetermined color to the light beam.

According to an alternative embodiment, the optical elements 21 are reflectors. According to yet another alternative embodiment, some of the optical elements 21 are collimators and other optical elements 21 are reflectors.

The optical elements 21 are arranged according to a matrix of optical elements in correspondence with the matrix of light sources 11. By the expression “in correspondence” it should be understood that the two matrices have the same dimensions and the same pitches. Advantageously, the optical elements have identical or similar dimensions with respect to each other, in particular dimensions allowing the correspondence of the matrix of optical elements 21 with the matrix of light sources 11. However, the optical elements can also have dimensions different from each other. This characteristic makes it possible in particular to adapt the optical elements located on the edges of the optical module to the volume geometrically available in these zones. It may then prove necessary to increase or reduce the dimensions of the optical elements of these zones, or even to truncate them.

The matrix according to which the optical elements are arranged is planar. In other words, the optical elements 21 are arranged along the same plane. This plane is parallel to the plane of the support of the light sources.

The optical part 20 is monobloc, that is to say that the optical elements 21 are connected to each other in a rigid manner. This characteristic makes it easier to mount the optical part in the optical module during manufacture. Indeed the manipulation of a single piece is then necessary. By way of non-limiting example, the optical part 20 may be composed of optical elements 21 produced separately and then connected to each other, for example by gluing or by welding.

However, the optical part can also be composed of two or more separate optical elements 21. These separate optical elements 21 are then mounted on the same support, in particular the support 15 of the light sources, which makes it possible to secure them with respect to each other, thus forming the optical part. Alternatively, the separate optical elements 21 are juxtaposed and held against each other, for example by binding, to form the optical part.

According to one embodiment advantageously, the optical elements 21 are made in one piece to form the optical part 20, that is to say that they come from the same manufacturing steps, in particular the steps of injection and/or pressing. This characteristic facilitates the manufacture of the optical part because a single process is sufficient to manufacture the entire optical part.

The intersections between each of the optical elements 21 and all of the adjacent optical elements 21 which surround it form a square. Said intersections are shown in dotted lines in Figures 2a and 3a. This characteristic makes it possible to obtain a regular matrix, thus ensuring good lighting homogeneity over all of the dimensions of the liquid crystal screen 30. It should be noted that this characteristic does not concern the optical elements 21 located on the edges of the optical part, for which said intersections form a portion of a square.

According to an alternative embodiment, the intersections between each of the optical elements 21 and all of the adjacent optical elements 21 which surround it form a hexagon. This characteristic makes it possible to reduce the differences in distance between the center and the perimeter, formed by the hexagon, of each optical element 21 and thus to ensure good homogeneity of illumination of the liquid crystal screen 30 opposite each optical elements 21. It should be noted that this characteristic does not concern the optical elements 21 located on the edges of the optical part, for which said intersections form a portion of a hexagon.

We will now examine the shape of the optical elements 21 of the optical part 20, according to a first embodiment (FIGS. 2a and 2b), and according to a second embodiment (FIGS. 3a and 3b).

FIG. 2a shows a detail of the optical part and of the light source support, according to a first embodiment of the invention, seen in perspective. Figure 2b is a view of these elements according to the section A-A shown in Figure 2a, in which the liquid crystal display has been added.

As mentioned above, the intersections between each of the optical elements 21 and the set of adjacent optical elements 21 which surround it form a square. Thus the optical elements 21 each form a square delimited by the dotted lines visible in FIG. 2a. The optical elements 21 located on the edges of the optical part 20 each form a portion of a square. Each optical element 21 comprises light input face 22, oriented towards the associated light source 11, and a light output face 23, oriented towards the liquid crystal screen 30. The light input face 22 comprises a central zone 221 formed by a domed diopter, and a peripheral zone 222 in the form of an annular tooth and comprising a light entry diopter 2221 and a surface for total reflection of light 2222.

The rays from the light source 11 which impact the central zone 221 enter the optical element 21 through the domed diopter and are transmitted directly to the light output face 23. The rays from the light source 11 which impact the zone peripheral 222 enters the optical element 21 through the light entry diopter 2221 and are reflected for the most part on the total light reflection face 2222 to be directed towards the light exit face 23. Certain rays go directly from the light entry interface 2221 towards the light exit face 23, without being reflected on the total light reflection face 2222.

The light exit face 23 comprises a central zone 231 forming a cavity and surrounded by a peripheral zone 232. The peripheral zones 232 of optical elements 21 are interconnected and form a connected element, that is to say continuous and without recess, essentially plane within which the cavities formed by the central zones 231 are located. Each central zone forms an essentially plane disc connected to the peripheral zone 232 by a step or a recess. The surfaces of the central zones 231 and of the peripheral zones 232 include beading. The beading has the same dimensional characteristics (size, curvature) over the whole of the optical part 20 in order to ensure uniform appearance over the whole of said optical part 20. Alternatively, the beading may have different dimensional characteristics depending on the zone of the optical part 20 in order to be adapted to particular configurations of the optical part 20, for example when the latter has a curvature in certain zones.

Figure 3a shows a view similar to that of Figure 2a, in which only the optical part is shown, according to a second embodiment of the invention. Figure 3b is a view of the optical part along section B-B shown in Figure 3a.

As can be seen in FIG. 3a, the optical part according to this embodiment differs from the embodiment of FIG. 2a in that the light exit face 23 of the optical elements 21 does not include beading. The central zone 231, forming a cavity with respect to the peripheral zone 232, consists of an essentially flat face having in its center a recess 2311 of circular outline, concentric with the disc formed by the central zone 231.

The central zones 231 therefore form a series of hollow cavities with respect to the connected surface formed by the peripheral zones 232 adjoining the optical elements 21, each cavity being provided with a central recess 2311 .

In FIG. 3b it can be seen that the light entry face 22 has the same structure as in FIG. 2b, that is to say a central zone 221 formed by a domed diopter, and a peripheral zone of annular tooth and comprising a diopter for entering light 2221 and a face for total reflection of light 2222. Although not shown, the light sources as well as the liquid crystal screen have the same relative position as on the Figure 2a. The recesses 2311 have a curved shape whose concavity is oriented towards the liquid crystal screen.

Figure 4a shows a perspective view of the light module including a trim element and Figure 4b a sectional view along the C-C axis of Figure 4a.

In addition to the elements described in connection with Figures 1 to 3b, the light module 1 also comprises a covering element 40 which forms a mechanical connection between the support 15 of the light sources 11 and the liquid crystal screen 30.

The covering element 40 surrounds the optical part 20 and the light sources 11. It is positioned relative to the support 15 by pins 41 which pass through said support 15. It is fixed to the support 15 using screws 60 Other means of positioning and/or fixing can be used, such as for example lugs, clips, rivets.

At another end, the covering element 40 has a shoulder 42 intended to receive the liquid crystal screen 30. The latter is held in the shoulder by a cover 50 fixed to the covering element 40. Thus the liquid crystal screen 30 is sandwiched between the shoulder on the one hand and the cover on the other hand. The cover has a central opening 55 allowing the light from the module to propagate outwards.

The fixing of the cover 50 on the covering element 40 is made by several tabs 51 having a hole which cooperates with a lug 43 associated with said tab. This method of attachment, offset to the rear of the light module 1 relative to the direction of observation in normal use of said module, makes it possible to limit the visibility of the attachment. Other means of fixing are possible, for example screwing or gluing.

The trim element has a light-coloured inner face, in particular white, in order to improve the homogeneity of the lit appearance of the luminous module 1.

Thanks to this structure, the light module 1 has good compactness and good resistance to deformation and/or degradation during manipulation by an operator during assembly of the light device, thus allowing easy installation of said light module. in an automotive headlight or headlamp.

Claims (17)

Light module (1) for a motor vehicle comprising:

1. a matrix (10) of light sources (11), the light sources (11) emitting light rays in a common emission direction (X), when they are supplied with electricity;
2. a liquid crystal display (30);
3. an optical part (20) placed opposite the light sources (11) in said common emission direction (X) and receiving light rays emitted by the light sources (11), and transmitting them to the liquid crystal screen ( 30) along this said common emission direction (X), the optical part (20) comprising a plurality of optical elements (21).

Light module (1) according to Claim 1, characterized in that at least one optical element (21) is a collimator, preferably all of the optical elements (21) being collimators. Light module (1) according to any one of Claims 1 to 2, characterized in that the optical elements (21) have identical or similar dimensions. Light module (1) according to any one of Claims 1 to 3, characterized in that the optical elements (21) are arranged in a matrix of optical elements, in correspondence with the matrix (10) of light sources (11) . Light module (1) according to the preceding claim, characterized in that the matrix of optical elements is aligned with the matrix (10) of light sources (11). Light module (1) according to any one of Claims 1 to 5, characterized in that each optical element (21) comprises a light input face (22) opposite which a light source (11) is arranged. Light module (1) according to any one of Claims 1 to 6, characterized in that the optical part (20) is in one piece. Light module (1) according to any one of Claims 2 to 7, characterized in that the light entry face (22) of the at least one collimator has the shape of a hollow cylinder open at one of its ends, and closed by a domed face at the other end. Light module (1) according to the preceding claim, characterized in that each light source (11) opposite a collimator is located inside the hollow cylinder, on the side of the end where it is open, each collimator comprising a light exit face (23) through which light exits the light module. Light module (1) according to the preceding claim, characterized in that the said light output face (23) comprises optical patterns. Light module (1) according to any one of Claims 9 to 10, characterized in that the light exit faces (23) of each collimator are aligned along an exit plane. Light module (1) according to the preceding claim, characterized in that the liquid crystal screen (30) is parallel to the exit plane. Light module (1) according to any one of the preceding claims, characterized in that the light sources (11) are arranged on a common light-coloured, in particular white-coloured, support (15) and parallel to the screen at liquid crystals. Light module (1) according to the preceding claim, characterized in that the support (15) is flat. Light module (1) according to any one of Claims 13 to 14, characterized in that it also comprises a covering element (40) which forms a mechanical connection between the support (15) and the liquid crystal screen ( 30), and which surrounds the light sources (11) and the optical element (20). Light module (1) according to the preceding claim, characterized in that the covering element (40) has a light-coloured, in particular white-coloured, inner face. Luminous device for a motor vehicle comprising:

1. - a housing ;
2. - a light module (1) according to any one of the preceding claims;

characterized in that the light module (1) is arranged inside the housing.