WO2018141823A1

WO2018141823A1 - Display unit

Info

Publication number: WO2018141823A1
Application number: PCT/EP2018/052454
Authority: WO
Inventors: Michael Irzyk; Vincent GIROD; Thibault CABANA
Original assignee: Valeo Comfort And Driving Assistance
Priority date: 2017-02-02
Filing date: 2018-01-31
Publication date: 2018-08-09
Also published as: FR3062485B1; FR3062485A1; EP3577390A1

Abstract

The invention relates to a display unit (10) comprising: a screen (13) having controllable optical transmission and a first backlighting assembly (11) configured to emit first light radiation towards the screen so as to illuminate a first field of illumination after transmission by the screen. According to the invention, the display unit comprises a second backlighting assembly (12), situated between the screen and the first backlighting device and comprising: a light guide produced by means of an at least partially transparent plate (122), and a second light source (112) arranged on the periphery of the plate, the light guide being configured in such a way that second light radiation received from the second light source exits at least partly from said plate in the direction of the screen in order to illuminate, after passing through the screen, a second field of illumination at least partially separate from the first field of illumination.

Description

Display device

TECHNICAL FIELD TO WHICH THE INVENTION RELATES The present invention relates to a display device.

It relates more particularly to a display device comprising:

a screen having a controllable optical transmission, and

- a set of backlighting of the screen.

The invention is particularly applicable in a vehicle such as a motor vehicle.

BACKGROUND

More and more devices, such as portable telephones, laptops, or motor vehicles, are now equipped with a user interface comprising a screen, for example LCD, for displaying information.

Several individuals may be in the vicinity of such a screen and are then likely to view the information displayed by it.

In the case of a telephone or a laptop, for example, the fact that the displayed information can be viewed not only by the user of the device but also by other individuals located near the screen poses a problem of confidentiality when the displayed information, presenting a private character, is intended only for the user of the device.

To remedy this problem of confidentiality, it is known to provide a laptop screen with a privacy filter. This privacy filter filters the light emitted by the screen so that it only illuminates, after passing through the filter, an area of space, facing the screen, having a reduced angular width. Only the user of the laptop, whose head is located in front of the screen, can then view the information displayed. On the contrary, an individual whose head is offset laterally with respect to this zone of reduced angular width can not visualize this information.

In the case of a motor vehicle, it is known to have a screen at the front of the vehicle interior, for example at a central console of the vehicle, to display information for the driver, such as images captured by side or rear cameras of the vehicle, or navigational information relating to a route followed by the vehicle.

This screen can also be used to display information intended for the entertainment of passengers of the vehicle, in particular the front passenger of the vehicle. But this information, which does not provide assistance in driving the vehicle, can then be perceived by the driver and are thus likely to distract him from driving the vehicle.

OBJECT OF THE INVENTION

In this context, the present invention provides a display device comprising:

a screen comprising an input face and an output face, and having, between the input face and the output face, a controllable optical transmission, and

a first set of backlight arranged opposite the input face of the screen and comprising a first light source, the first set of backlighting being configured to transmit to the screen a first light radiation so as to illuminate, after transmission by the screen, a first lighting field.

According to the invention, the display device further comprises a second backlight device located between the screen and the first backlighting device, the second backlight device comprising:

a light guide made by means of an at least partially transparent plate, and

a second light source disposed at the periphery of the plate, the light guide being configured so that a second light radiation received from the second light source at least partly leaves said plate in the direction of the screen to illuminate, after passing through the screen, a second lighting field at least partially disjoint from the first lighting field.

The at least partially transparent plate of the second backlighting system passes, at least in part, the first light radiation emitted by the first backlighting system, so that it can reach the screen to then illuminate the first lighting field.

Thus, in a first configuration, for which the first light source is on and the second light source is off, the light which out of the screen illuminates only the first field of illumination.

On the contrary, in a second configuration, for which the second light source is on and the first light source is off, the light coming out of the screen illuminates only the second light field.

As the display device is configured so that the first CH1; CH1 'and second CH2 lighting fields are at least partially disjoint, the display device 10; 10 'advantageously makes it possible to address the displayed information:

either to a first user only, whose head is located in the first lighting field CH1; CH1 ', which is obtained in the first lighting configuration,

- Or, in the second lighting configuration, to one or more other users whose head is located outside the first lighting field CH1; CH1 ', in this case in a part of the second illumination field CH2 distinct from the first illumination field CH1; CH1 '.

This display device thus makes it possible to select, from among several users of the device, located at different positions, the one or those for which the displayed information is visible.

This property is particularly interesting in terms of protecting the confidentiality of the information displayed.

It is also particularly interesting when the display device is installed in a vehicle, such as a motor vehicle, because it allows, depending on whether the information displayed helps the driving of the vehicle, or is on the contrary likely to distract a driver from the vehicle. vehicle, to make this information visible or invisible to the driver.

Furthermore, the tilting of the first to the second lighting configuration can be realized in a fully electric manner, without mechanical displacement of moving parts, which is interesting in terms of robustness and response time to a tilt control.

Other nonlimiting and advantageous features of ^* according to the invention are the following:

the first set of backlighting is configured to emit the first light radiation with a reduced angular width, less than an angular width presented by the second light radiation at the output of the second set of backlighting;

the first backlight assembly comprises an optical filter which imposes on the first light radiation said reduced angular width;

- The first set of backlight is configured for the first light radiation sort of the first set of backlight with a mean direction of propagation offset angularly with respect to a mean direction of propagation of the second light radiation issuing from said plate;

the first backlighting assembly comprises an optical component adapted to deflect the first light radiation so that, when leaving the first backlighting assembly, it has said mean propagation direction angularly offset relative to the average direction of the light; propagation of the second light radiation coming out of said plate;

the second light source comprises at least one electroluminescent diode;

the light guide of the second backlighting assembly comprises a partially reflecting coating applied on one side of said plate located on the side of the first backlighting assembly with respect to the plate;

said coating is partially diffusing;

- The first set of backlighting comprises another light guide made by means of another at least partially transparent plate, disposed opposite the input face of the screen, the first light source being disposed at the periphery of said other plate;

said other plate is configured so that the first light radiation received from the first light source emerges at least in part from said other plate in the direction of the screen;

- The light guide of the first set of backlight comprises a reflective coating applied to one side of the plate of the first set of backlight which is located on a side opposite the screen relative to this plate;

the display device comprises a polarization recycling filter disposed between the second backlight assembly and the input face of the screen;

- the display device is configured so that, being installed in the front part of a vehicle interior, in front of a driver's seat and a front passenger seat of the vehicle, the second lighting field includes at least partially the driver's seat, and the first lighting field excludes the driver's seat;

the display device is configured so that, being installed in the front part of a vehicle cabin, in front of a driver's seat and a front passenger seat of the vehicle, an angular opening of the second lighting field is large enough to at least partially include the driver's seat, and a reduced angular aperture of the first illumination field is small enough to exclude the driver's seat;

the display device comprises a control unit programmed to control the optical transmission of the screen so as to display data, and to control the ignition selectively of either the first light source or the second source; of light, according to said data to be displayed.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT The following description with reference to the accompanying drawings, given by way of non-limiting examples, will make it clear what the invention consists of and how it can be implemented.

In the accompanying drawings:

FIG. 1 schematically represents, in section, a display device according to a first embodiment implementing the teachings of the invention,

FIG. 2 diagrammatically, seen from above, a first vehicle in which the display device of FIG. 1 is installed,

FIG. 3 schematically represents, in section, a display device according to a second embodiment implementing the teachings of the invention,

FIG. 4 schematically represents a second vehicle in which the display device of FIG. 3 is installed, a first field illuminated by this display device being also represented, FIG. 5 diagrammatically represents the vehicle of FIG. 4, and a second field illuminated by the display device which equips it.

Figures 1 and 3 show schematically the main elements of a display device 10; 10 'according to a first, and respectively a second embodiment according to the teachings of the invention.

The identical or corresponding elements of these two embodiments of the display device 10; 10 'will be referenced by the same signs, and will not be described each time.

Whatever the embodiment of the display device 10; 10 ', it comprises a screen 13 (FIGS. 1 and 3) comprising an input face 13E and an output face 13S (FIGS. 1 to 5), and presenting, between the input face 13E and the face of 13S output, a controllable optical transmission.

More particularly, the screen 13 comprises several distinct elements (not shown), each of which has a controllable optical transmission. An image, containing information to be displayed, can thus be formed by transmission of light radiation through the screen 13, the pixels of this image then corresponding to said distinct elements of the screen.

The screen 13 may be produced by means of a liquid crystal screen, for example of the TFT ("Thin-Film Transistors") type, or thin-film transistors.

The input 13E and output 13S faces of the screen 13 are here substantially parallel to each other.

The display device 10; 10 'also comprises a first set of backlight 1 1; 1 1 '(Figures 1 and 3), arranged vis-à-vis the input face 13E of the screen.

The first set of backlight 1 1; 11 'comprises a first light source 11 1, and is configured to transmit to the screen 13 a first light radiation so as to illuminate, after transmission by the screen, a first illumination field CH1; CH1 '(Figures 2 and 4).

The first lighting field CH1; CH1 'corresponds to the region of the space reached by the first light radiation coming out of the screen 13, or, at least, to a part of this region in which the light intensity of the first radiation is sufficient for it to be is perceived by a user. The first lighting field CH1; CH1 'corresponds to the region of space from which a user can view the information displayed by the screen 13, when the first light source is turned on.

In both embodiments of the display device 10; 10 'described here, the first set of backlight 1 1; 1 1 'includes:

a first light guide, made by means of a first plate

121 at least partially transparent, arranged vis-à-vis the input face 13E of the screen, and

the first light source 1 1 1 disposed at the periphery of the first plate 121.

Per periphery of the plate is meant here an area located near the edge of the plate, and sufficiently far from the center of the plate not to be located right of the screen 13.

The first plate 121 is configured so that the first light radiation, initially emitted by the first light source 11 1, then enters through the first plate 121 to exit, at least in part, in the direction of the screen 13.

This first plate 121 is for example made of transparent plastic material such as PMMA or polycarbonate. It extends substantially parallel to the entrance face of the screen. This first plate has two main faces, one of which is approximately parallel to the input face 13E of the screen, connected by a wafer. These two main faces are slightly inclined towards each other (they are not completely parallel to each other), forming between them an angle of, for example, between 0.5 and 5 degrees.

The light guide of the first set of backlight 1 1; 1 1 'also comprises a reflective coating 131 applied on the main face of this first plate 121 which is located, relative to the plate 121, opposite the screen 13.

In both embodiments of the display device 10; 10 'described here, the first light source 1 1 1 is disposed opposite the edge of the first plate 121, the side where the plate has the largest thickness (Figures 1 and 3).

The first light source 11 may notably be produced by means of one or more sources of elementary lights, such as electroluminescent diodes arranged, as explained above, opposite the edge of the first plate 121.

It can be provided that this or these elementary light sources are arranged in a plane not perpendicular to the screen to be illuminated. A reflector system may be provided to collect the first light radiation, initially emitted by this or these elementary light sources, and to direct it to the first plate.

The first light radiation, emitted by the first light source 1 1 1, enters here into the first plate 121 at its edge.

The slight inclination, with respect to one another, of the two main faces of the first plate 121 then makes it possible both to guide the first light radiation inside the latter, and to bring it out gradually, as its propagation in the plate 121, by the main face located on the side of the screen 13. The reflective coating 131 applied to the other main face of the plate prevents an output of the first light radiation at the level of this face, and thus improves the efficiency with which the first light guide redirects to the screen 13, the light radiation emitted initially by the first light source 1 1 1.

In other embodiments of the display device, not shown, the first light guide described above could be omitted, the first light source then being arranged to directly emit the first radiation in the direction of the screen. In this case, the first light source could for example be made by means of one or more light-emitting diodes or of one or more fluorescent tubes, arranged one (or the other) next to the others in a plane substantially parallel to the input face of the screen, vis-à-vis this input face. In these embodiments, a reflector system may be provided to collect the first light radiation emitted by the first source, and to direct it to the screen.

According to a remarkable characteristic, the display device 10; 10 'comprises a second set of backlight 12, located between the screen 13 and the first backlight device 11; 1 1 ', the second set of backlight 12 comprising:

a second light guide made by means of a second at least partially transparent plate 122, and

a second light source 1 12 disposed at the periphery of the second plate 122.

Particularly noteworthy, the second light guide is configured so that a second light radiation, received from the second light source 1 12, at least partially out of the second plate 122 towards the screen 13 (arrow F2 of Figures 1 and 3) for illuminating, after crossing the screen, a second illumination field CH2 at least partially disjoint from the first illumination field CH1; CH1 '(Figures 2, 4 and 5).

The second lighting field CH2 corresponds (as for the first lighting field) to the region of the space reached by the second light radiation coming out of the screen 13, or, at least, to a part of this region. wherein the light intensity of the second radiation is sufficient for it to be perceived by a user.

As the second plate 122 is at least partially transparent, at least a portion of the first light radiation from the first backlight system 1 1; 1 1 ', can cross the second set of backlight 12 to reach the screen 13 and then illuminate the first lighting field CH1; CH1 ', as shown schematically by the arrow F1 of Figures 1 and 3.

The positioning of the second light source 12 at the periphery of the second plate 122 also makes it possible to prevent this source from masking part of the first light radiation.

Thus, in a first configuration, for which the first light source 1 1 1 is lit and the second light source 1 12 is off, the light coming out of the screen 13 illuminates only the first lighting field CH 1; CH1 '.

In contrast, in a second configuration, for which the second light source 1 12 is on and the first light source 1 1 1 is off, the light coming out of the screen 13 illuminates only the second lighting field CH 2.

The display device 10; 10 'thus advantageously makes it possible to select, from among several users of the device located at different positions, the one or those for which the displayed information is visible.

The assembly comprising the second plate 122 and the second light source 1 12 is here identical, or at least similar, to the assembly comprising the first plate 121 and the first light source 1 1 1 which have been described in detail above.

Thus, the second plate 122 extends substantially parallel to the input face 13E of the screen, and has two main faces, one of which is approximately parallel to this input face 13E, connected by a wafer. These two main faces are slightly inclined towards one another, forming between them an angle of, for example, between 0.5 and 5 degrees.

In both embodiments of the display device 10; 10 'described here, the second light source 1 12, made for example by means of one or more light-emitting diodes, is arranged opposite the edge of the second plate 122, on the side where this plate presents the the greatest thickness.

A partially reflective coating 132 is applied to the main face of the second plate 122 which is located, with respect to this plate 122, on the side of the first set of backlight 11; 1 1 '. This coating 132 is partially transparent.

Unlike the reflective coating 131 applied to the first plate 121, the coating 132 applied to the second plate 122 is therefore not completely reflective.

It thus passes part of the first light radiation from the first set of backlight 1 1; 1 1 ', while favoring, for the second light radiation, an output of the second plate 122 towards the screen 13.

In the first and second embodiments described here, the partially reflective coating 132 applied to the plate 122 of the second backlight assembly 12 is further partially diffusing, thereby improving the illumination homogeneity of the screen 13.

At the output of the second backlighting assembly, 12, the second light radiation has a mean direction of propagation, which is here substantially perpendicular to the input face 13E, and thus also to the output face 13S of the screen 13 .

This mean direction of propagation corresponds, for example, to the average direction of the light rays of a second beam of light rays, in the form of which the second light radiation emerges from the second set of backlighting 12.

At the output of the second backlighting assembly, 12, the second light radiation also has a given angular width, or, otherwise, a given angular dispersion.

This angular width corresponds for example to the angular width of the second beam of light rays mentioned above.

This angular width is defined in a first plane, here approximately perpendicular to the exit face 13S of the screen 13 (plane (x, y), in FIGS. 1 and 3).

In the first and second embodiments described herein, the second backlight assembly 12 includes an optical filter 142 disposed in the path of the second light radiation between the second plate 122 and the screen 13, which sets the angular width. mentioned above.

This optical filter 142 is for example a flap filter, formed of a film of transparent material including opaque barriers which extend, in the film, perpendicular to a mean plane of the film, the height and spacing of these barriers determining the maximum angular aperture imposed by the filter to light radiation passing through it.

The angular aperture AGL2 of the second illumination field CH2 (FIGS. 2 and 5) is equal to, or at least determined by, the angular width presented by the second light radiation at the output of the second set of backlight.

This angular aperture AGL2 designates, for example, the full width at half maximum ("full width at half maximum", according to the Anglo-Saxon denomination) of the angular distribution of light intensity in the second lighting field, illuminated by the second light radiation (that is, the distribution, as a function of an angular position in the second field, of the luminous intensity of the second radiation).

The second set of backlight 12 is configured here so that the angular aperture AGL2 of the second illumination field CH2 allows several users occupying different lateral positions in front of the screen 13, to display the information displayed by it. For this, the second set of backlight 12 is configured for example so that the angular aperture AGL2 of the second lighting field CH2 is between 80 and 140 degrees, or between 80 and 120 degrees.

The display device 10; 10 'further comprises, here, an optional optical filter 14 disposed between the second set of backlight 12 and the input face 13E of the screen.

This optional optical filter 14 is configured to limit the angular dispersion of the first and second light radiations in a second plane (plane (z, x), in FIGS. 1 and 3), here approximately perpendicular to the exit face 13S of the screen 13 and in the aforementioned foreground.

This optional optical filter 14 can also be realized by means of a flap filter.

In a variant not shown, the optional optical filter is omitted, and the optical filter of the second backlight assembly is configured to limit the angular dispersions of the light radiation that it transmits, both in the foreground and in the second plane. supra.

In the first and second embodiments described herein, the first backlight assembly 11; 1 1 'is configured to emit the first light radiation with a reduced angular width, smaller than the angular width that the second light radiation at the output of the second backlight assembly 12 presents.

The first set of backlight 1 1; 1 1 'is more precisely configured to emit the first light radiation so that it has said reduced angular width in the aforementioned first plane, wherein the second light radiation has said given angular width.

The first set of backlight 1 1; 1 1 'here too, includes an optical filter 141 (Figures 1 and 3), imposing the first light radiation said reduced angular width. This optical filter 141 is for example a flap filter. It is arranged in the path of the first light radiation between the first plate 121 and the second backlight assembly 12.

The first set of backlight 1 1; 1 1 'also comprises, here, a diffuser 1 61, optional, disposed between the first plate 121 and the optical filter 141. This diffuser makes it possible to improve the uniformity of illumination of the screen 13.

Note also that, as the first light radiation is emitted with a reduced angular width, smaller than that imposed by the optical filter 142 of the second set of backlight 12, the (reduced) angular width of the first radiation is not modified, at least is slightly modified, by the optical filter 142 of the second set of backlight 12.

As previously, the angular aperture AGL1, AGL1 'of the first illumination field CH1; CH1 '(Figures 2 and 4) is therefore equal to, or at least determined by the reduced angular width presented by the first light radiation at the output of the first set of backlight 1 1; 1 1 '.

The first lighting field CH1; CH1 'thus has, in the first plane mentioned above, an angular aperture AGL1, AGL1' lower than that AGL2 of the second illumination field CH2. Otherwise formulated, in this first plane, the first lighting field CH1; CH1 'is angularly narrower than the second field of illumination.

The first set of backlight 1 1; 1 1 'is configured here so that the angular aperture AGL1, AGL1' of the first illumination field CH1; CH1 'is small enough so that, in the first lighting configuration of the screen, only a user located on the average axis DM; DM1 of the first illumination field CH1; CH1 'can view the information displayed on the screen.

For this, the first set of backlight 1 1; 1 'is for example configured so that the angular opening AGL1, AGL1' of the first field lighting CH1 is between 10 and 60 degrees, or so that it is less than 40 degrees.

The angular aperture AGL1, AGL1 'of the first illumination field CH1; CH1 'designates, for example, as previously for the second lighting field, the full width at half height of the angular distribution of light intensity in the first lighting field, illuminated by the first light radiation.

The display device 10; 10 'further comprises, here, a polarization recycle filter 15, disposed between the second backlight assembly 12 and the input face 13E of the screen. This polarization recycling filter 15, for example made by means of a film of the DBEF type produced by the company 3M, makes it possible to increase the brightness of the image generated by the display device.

In the first and second embodiments described herein, the display device 10; 10 'further comprises a control unit (not shown) programmed to control the optical transmission of the screen 13 so as to display data, and to control the ignition, selectively, according to said data to be displayed:

- either of the first light source 1 1 1 only, which corresponds to the first lighting configuration mentioned above,

- Or the second light source 1 12 only, which corresponds to the second lighting configuration mentioned above.

Thus, when the display device 10; 10 'is for example intended to be installed in a vehicle, the control unit can be programmed to:

- control the ignition of the first light source 1 1 1 only, when the data to be displayed is likely to distract the driver, and

- Control the ignition of the second light source 1 12 when the data to be displayed is likely to help or assist the driver in driving the vehicle.

Alternatively, when the display device is intended for example to equip a portable computer, the control unit can be programmed to:

- control the ignition of the first light source 1 1 1 only, when the data to be displayed has a private character or confidential, and

- Control the ignition of the second light source 1 12 when the data to be displayed has a public character, as may be the case for example for journalistic information.

In the first embodiment of the display device 10 (FIGS.

1 and 2), the first light radiation has, at the output of the first set of backlight 1 1, a mean direction of propagation identical to, or at least close to that presented by the second light radiation at the output of the second plate 122 .

In this first embodiment, the first lighting field

CH1 and the second lighting field CH2 are therefore both centered on the same average axis DM (FIG. 2). This average axis DM is here substantially perpendicular to the output face 13S of the screen.

On the contrary, the display device 10 'according to the second embodiment (FIGS. 3 to 5) is configured so that the first light radiation has, at the output of the first backlight assembly 11', an average direction of propagation. angularly offset from that of the second light radiation emerging from the second plate 122.

In this second embodiment, the average axis DM1 of the first illumination field CH1 'and the average axis DM2 of the second illumination field CH2 are thus angularly offset with respect to each other. This angular offset is noted AGLD. It is for example between 5 and 30 degrees.

Due to this angular offset, the first and second lighting fields are more clearly distinguishable from each other. This offset makes it possible in particular to enlarge an area of the second lighting field that is not reached by the first light radiation, thus facilitating the addressing of the displayed information either to a user located in this area, or only to a user. located in the first field of illumination.

The display device 10 'is more precisely configured, in this second embodiment, so that the average axis DM1 of the first lighting field CHI' is substantially perpendicular to the output face 13S of the screen, and for that the average axis DM2 of the second illumination field CH2 is angularly offset from the angle AGLD relative to a direction DN perpendicular to the exit face 13S of the screen 13 (FIG. 4). In order to introduce this angular offset, the first backlighting assembly 11 'of the display device 10' here comprises an optical component 151, adapted to deflect the first light radiation so that it has, on leaving the first set of backlight lighting 1 1 ', said mean direction of propagation offset angularly.

This optical component 151 here has a prismatic structure, that is to say that one of these main faces has a succession of facets each inclined with respect to an average plane defined by this main face.

As a variant, this optical component could be produced by means of a transparent parallel plate having a non-zero refractive index gradient.

Alternatively, this optical component could be omitted, the above-mentioned shift being achieved by bulk tilting the first backlight assembly with respect to the second backlight assembly.

Two advantageous uses of the display device 10; 10 'in a first 1 and a second vehicle 1' are now described in more detail with reference to FIGS. 2, 4 and 5.

2 schematically shows, in a partial manner, the first vehicle 1, here a motor vehicle such as a car or a truck, comprising the display device 10 according to the first embodiment.

Figures 4 and 5 show for their part, schematically and partially, the second vehicle 1 ', here a motor vehicle, comprising the display device 10' according to the second embodiment.

To facilitate the understanding of the figures, a system of three axes X, Y and Z, orthogonal two by two, is introduced.

The X axis corresponds to the longitudinal axis of the vehicle 1; 1 '. It is directed from the rear to the front of the vehicle 1; 1 ', in a direction substantially parallel to the chassis of the latter. The Z axis is meanwhile substantially perpendicular to the vehicle frame, and is directed from the bottom to the top.

The first vehicle 1 and the second vehicle 1 'each comprise a driver seat 2A and a front passenger seat 2B.

In the first 1, as in the second vehicle 1 ', the display device 10; 10 'is installed here in the front part of a passenger compartment of the vehicle 1; 1 ', in front of the driver's seat 2A and the front passenger seat 2B. The display device 10; 10 'according to the first and second embodiments is more precisely configured, here, so that, thus being installed in the passenger compartment of the vehicle 1; 1 ',

the second lighting field CH2 at least partially includes the driver's seat 2A, including in particular a POSA position usually occupied by the driver's head of the vehicle, and that

the first lighting field CH1; CH1 'excludes the driver's seat 2A, in particular excluding said POSB position.

It is also configured so that, thus installed, the first lighting field CH1; CH1 'at least partially includes the front passenger seat 2B, including in particular a POSB position usually occupied by the head of a front passenger of the vehicle.

Here, the display device 10; 10 'is installed more precisely so that the first plane, in which is defined the angular aperture AGL1; AGL1 'of the first illumination field CH1, CH1', as well as the angular aperture AGL2 of the second illumination field CH2, corresponds to the plane (x, y), that is to say, so that this foreground extends substantially parallel to the chassis of the vehicle 1; 1 '.

The display device 10; 10 'is then configured so that, thus installed in the vehicle 1; 1 ',

the angular aperture AGL2 of the second illumination field CH2 is sufficiently large to include at least partially the driver seat 2A, and so that

- the angular aperture AGL1; AGL1 ', reduced, of the first illumination field CH1; CH1 'is small enough to exclude the driver's seat

2A.

In the first vehicle 1, the display device 10 is installed more precisely opposite the front passenger seat 2B (FIG. 2), for example at the level of a dashboard of the first vehicle 1, the face of 13S output of its screen 13 facing the passenger seat 2B. The display device 10 is arranged so that the exit face 13S of its screen 13 extends substantially perpendicularly to the longitudinal axis X of the first vehicle 1.

In this situation, the ranges of values indicated previously for the angular openings AGL1 and AGL2 generally make it possible to obtain that the first illumination field CH1 includes the POSB position and excludes the POSA position, while the second illumination field CH2 includes the POSB position.

In the second vehicle 1 ', the display device 10' is installed approximately at equal distances from the driver's seat 2A and the front passenger seat 2B (FIGS. 4 and 5). It can for example be installed at a central console of the second vehicle 1 '.

The exit face 13S of its screen 13 is inclined with respect to the longitudinal axis X of the second vehicle 1 'so that this exit face is oriented at least partly towards the front passenger seat 2B.

The direction DN perpendicular to the exit face 13S of the screen 13 is then angularly offset, by an angle AGLI, with respect to the longitudinal axis X of the second vehicle.

The angle AGLI is formed here, between the longitudinal axis X and the direction DN, in the plane (x, y), that is to say in a plane substantially parallel to the chassis of the vehicle. It is for example between 10 and 30 degrees.

In this situation, the ranges of values indicated above for the angular apertures AGL1 'and AGL2, and for the angular offset AGLD generally make it possible to obtain that the first illumination field CH1 includes the POSB position and excludes the POSA position, while the second lighting field CH2 includes the position POSB. In particular, the following values give very satisfactory results in practice: AGLI = 20 degrees, AGLD = 10 degrees, AGL1 '= 20 degrees, and AGL2 = 120 degrees.

The display device according to the teachings of the invention can of course be used in a different context from that presented above. It can for example advantageously equip a laptop.

Furthermore, in other embodiments, not shown, the display device could be configured so that the first and second lighting fields are angularly offset relative to one another, while having openings angular equal, or at least close (unlike the second embodiment described above, wherein the second field is wider than the first).

In this configuration, it is also possible to provide that the electronic control unit is configured to control alternately, from repeatedly over time:

the ignition of the first light source alone, and the display by the screen of a first data item intended for a first user, and then

- The ignition of the second light source alone, and the display by the screen of a second data for a second user.

Thanks to this rapid alternation, interlaced over time, the illumination of the first and second lighting fields, the first and the second user can view, with a continuous display printing, the data that concerns him.

Claims

1. Display device (10; 10 ') comprising:

a screen (13) comprising an input face (13E) and an output face (13S), and having, between the input face (13E) and the output face (13S), a controllable optical transmission, and

a first set of backlighting (1 1; 1 1 ') disposed opposite the input face (13E) of the screen and comprising a first light source (1 1 1), the first set of backlight (1 1; 1 1 ') being configured to transmit to the screen (13) a first light radiation so as to illuminate, after transmission by the screen, a first lighting field (CH1; CH1 '),

the display device (10; 10 ') being characterized in that it further comprises a second backlight assembly (12) located between the screen (13) and the first backlighting device (11). 1 1 '), the second backlight assembly (12) comprising:

a light guide made by means of a plate (122) at least partially transparent, and

a second light source (1 12) disposed at the periphery of the plate (122),

the light guide being configured so that a second light radiation received from the second light source (1 12) emerges at least in part from said plate (122) towards the screen (13) to illuminate, after passing through the screen, a second lighting field (CH2) at least partially disjoint from the first lighting field (CH1; CH1 ').

The display device (10; 10 ') according to claim 1, wherein the first backlight assembly (11; 11') is configured to emit the first light radiation with a reduced angular width less than an angular width presented by the second light radiation at the output of the second backlight assembly (12).

The display device (10; 10 ') according to claim 2, wherein the first backlight assembly (11; 11') comprises an optical filter (141). imposing on the first light radiation said reduced angular width.

4. Display device (10 ') according to one of claims 1 and 3, wherein the first set of backlight (1 1') is configured so that the first light radiation out of the first set of backlight (1 1 ') with a mean direction of propagation offset angularly with respect to a mean direction of propagation of the second light radiation issuing from said plate (122).

The display device (10 ') according to claim 4, wherein the first backlight assembly (11') comprises an optical component (151) adapted to deflect the first light radiation so that it has, leaving the first set of backlight (1 1 '), said mean direction of propagation offset angularly with respect to the mean direction of propagation of the second light radiation issuing from said plate (122).

6. Display device (10; 10 ') according to one of claims 1 to 5, wherein the second light source (1 12) comprises at least one light emitting diode.

The display device (10; 10 ') according to one of claims 1 to 6, wherein the light guide of the second backlight assembly (12) comprises a partially reflective coating (132) applied to one side said plate (122) located on the side of the first backlight assembly (11, 11 ') relative to the plate (122).

The display device (10; 10 ') according to claim 7, wherein said coating (132) is partially diffusing.

9. Display device (10; 10 ') according to one of claims 1 to 8, wherein the first set of backlight (1 1; 1 1') comprises another light guide made by means of another at least partially transparent plate (121) disposed opposite the input face (13E) of the screen, the first light source (1 1 1) being disposed on the periphery of said another plate (121), said other plate being configured so that the first light radiation received from the first light source (1 1 1) emerges at least in part from said other plate (121) in the direction of the screen (13) .

The display device (10; 10 ') according to claim 9, wherein the light guide of the first backlight assembly (1 1; 1 1') comprises a reflective coating (131) applied to a face of the plate (121) of the first backlight assembly (11, 11 ') which is located on a side opposite the screen (13) with respect to this plate.

1 1. Display device (10; 10 ') according to one of claims 1 to 10, comprising a polarization recycling filter (15) arranged between the second backlight assembly (12) and the input face (13E ) of the screen.

12. Display device (10; 10 ') according to one of claims 1 to 1 1, configured so that, being installed in the front part of a vehicle cabin (1; 1'), in front of a driver's seat (2A) and a front passenger seat (2B) of the vehicle (1; 1 '),

the second lighting field (CH2) at least partially includes the driver seat (2A), and

- the first lighting field (CH1; CH1 ') excludes the driver's seat

(2A).

13. Display device (10; 10 ') according to one of claims 2 to 1 1, claims 4 to 1 1 being taken in dependence on one of claims 2 and 3, configured so that, being installed at the front of a vehicle interior (1; 1 '), in front of a driver's seat (2A) and a front passenger seat (2B) of the vehicle,

an angular opening (AGL2) of the second lighting field (CH2) is sufficiently large to include at least partially the driver's seat

(2A), and

- A reduced angular aperture (AGL1; AGL1 ') of the first illumination field (CH1; CH1') is sufficiently small to exclude the driver seat (2A).

14. Display device (10; 10 ') according to one of claims 1 to 13, further comprising a control unit programmed to control the optical transmission of the screen (13) so as to display data, and for controlling the ignition selectively of either the first light source (1 1 1) or the second light source (1 12) as a function of said data to be displayed.