Head-up display device for a vehicle

Abstract

The present invention relates to a head-up display device (16) for a vehicle, comprising: a. a carrier (20) comprising a reflector element (22), b. an emission source (24) able to emit a light beam, called the useful beam (Fu), and c. an optical unit (26) able to convey the useful beam (Fu) towards the reflector element (22) such that the reflector element (22) is able to reflect the useful beam (Fu) in order to form a useful image (IM) in a window of observation of a driver (18) or of at least one passenger (19) of the vehicle (10), the optical unit (26) comprising an optical system having both a reflective property and a scattering property, called the scattering mirror, the scattering mirror being able to receive the useful beam (Fu), and to reflect it and scatter it such as a secondary emission source.

Description

[0001] DESCRIPTION

[0002] TITLE: Head-up display device for a vehicle

[0003] The present invention relates to a head-up display device for a vehicle. The present invention also relates to a vehicle comprising such a head-up display device.

[0004] A display device, such as a head-up display device, conventionally comprises an information emission source associated with a set of optics for emitting a light beam towards a semi-reflective or reflective support. The reflection of the light beam on the semi-reflective or reflective support makes it possible to generate a useful image observable by a user, for example the driver of a vehicle.

[0005] However, such a display device is generally heavy and bulky, particularly due to the optical assembly. Thus, the performance of the display device is generally limited so that it is less bulky and can be integrated into the dashboard of a vehicle. In other cases, the display device is not integrated into the dashboard due to its volume.

[0006] There is therefore a need for a display device allowing the display of information useful for driving a vehicle which is compact and easy to integrate into a vehicle.

[0007] For this purpose, the present description relates to a head-up display device for a vehicle, comprising: a. a support comprising a reflector element, b. an emission source capable of emitting a light beam, called a useful beam, and c. an optical unit capable of conveying the useful beam towards the reflector element so that the reflector element is capable of reflecting the useful beam to form a useful image in an observation window of a driver or at least one passenger of the vehicle, the optical unit comprising an optic having both a reflective property and a diffusing property, called a diffusing mirror, the diffusing mirror being capable of receiving the useful beam, and of reflecting and diffusing it like a secondary emission source.

[0008] According to other advantageous aspects, the display device comprises one or more of the following characteristics, taken individually or in all technically possible combinations: - the bidirectional reflectance distribution function, called BRDF, of the diffusing mirror is constant over the surface of the secondary emission source seen from the driver's or passenger's observation window;

[0009] - the reflection coefficient of the diffusing mirror is greater than or equal to 90 percent, preferably strictly greater than 92 percent, advantageously strictly greater than 95 percent;

[0010] - the diffusing mirror is formed from a stack of layers including: a substrate, a fixing layer and a reflective layer, the substrate having a textured face conferring the diffusing property to the diffusing mirror, the fixing layer being fixed on the textured face of the substrate, the reflective layer being fixed on the fixing layer;

[0011] - the textured face of the substrate is formed from an arrangement of diffusing elements on said textured face;

[0012] - the diffusing elements are arranged isotropically;

[0013] - each diffusing element has at least two planes of symmetry, preferably the diffusing elements having a spherical shape;

[0014] - the diffusing mirror comprises at least one oxide layer fixed on the reflective layer;

[0015] - the diffusing mirror is the only diffusing element of the optical block.

[0016] The present description also relates to a vehicle comprising a display device as described previously.

[0017] Other features and advantages of the invention will become apparent upon reading the following description of embodiments of the invention, given by way of example only, and with reference to the drawings which are:

[0018] - figure 1, a schematic representation of a passenger compartment of a vehicle, the vehicle comprising an example of a display device,

[0019] - figure 2, a schematic representation of an example of a display device,

[0020] - figure 3, a schematic representation of an example of a diffusing mirror,

[0021] - figure 4, a schematic representation illustrating a gain in the number of optics provided by a display device according to the invention compared to a display device of the state of the art,

[0022] - figure 5, another schematic representation illustrating a gain in the number of optics provided by a display device according to the invention compared to a display device of the state of the art, and - figure 6, yet another schematic representation illustrating a gain in the number of optics provided by a display device according to the invention compared to a display device of the state of the art.

[0023] A vehicle 10 is illustrated in Figure 1.

[0024] In this example, the vehicle 10 comprises, in a passenger compartment 11, a windshield 12, a dashboard 14 and a head-up display device 16. The dashboard 14 is defined as being a shelf extending over the entire width of the vehicle 10, below the windshield 12 and above the feet of the driver 18 and, where applicable, of the front passenger.

[0025] The vehicle 10 is, for example, a land, air or naval vehicle. The land vehicle is, for example, a motor vehicle (Figure 1) or a railway vehicle.

[0026] In one example, the display device 16 is arranged in the vehicle 10 so as to allow the display of information in an observation window (in English "eyebox") of the driver 18 in the driving position or of one or more passengers 19 of the vehicle 10 (front or rear passengers).

[0027] In an exemplary implementation, the display device 16 is integrated into the dashboard 14 of the display device 16.

[0028] The information is, for example, vehicle control information. For example, the control information is on-board instruments of the vehicle 10. The on-board instruments are indicators or tell-tales which inform the driver 18 of a vehicle 10 about the driving parameters (speed, acceleration, temperature, etc.) and the operation of the vehicle 10, in particular of the engine of the vehicle 10. For a motor vehicle, the on-board instruments comprise, for example, at least a rev counter, a speedometer, a fuel gauge and a coolant temperature indicator.

[0029] In addition or as a variant, control information is information useful for driving such as navigation (mapping, positions, directions) or traffic conditions (traffic jams, roadworks).

[0030] In addition or as a variant, the information is other information such as multimedia services, or information relating to the air conditioning of the vehicle 10.

[0031] As illustrated in FIG. 2, the display device 16 comprises a support 20, an emission source 24 and an optical unit 26.

[0032] As seen in Figure 2, the support 20 comprises a base element 21 and a reflector element 22.

[0033] In an exemplary embodiment, the base element 21 is transparent.

[0034] The base element 21 has an inlet diopter and an outlet diopter. Each of the inlet diopter and the outlet diopter has an outer face and an inner face opposite the outer face. The outer face of each diopter is a face oriented towards the outside of said diopter, that is to say towards the external environment (the air). The inner face of each diopter is oriented towards the inside of said diopter.

[0035] Optionally, the support 20 comprises at least one layer of a transparent material between the input diopter and the output diopter of the base element 21. The transparent material is, for example, glass, plastic, ethylene vinyl acetate (EVA), or polyvinyl butyral (PVB).

[0036] In this exemplary embodiment, the support 20 is, for example, a blade also called a “combiner”. Alternatively, the support 20 is a windshield, such as the windshield 12 of the vehicle 10 in which the device 16 is integrated.

[0037] In another exemplary embodiment, the base element 21 is opaque, i.e., of zero transparency. Alternatively or additionally, the base element 21 is tinted or has an activatable tint (photo or electrochromic).

[0038] The reflective element 22 is at least partially reflective.

[0039] The reflective element 22 is, for example, a coating or treatment (for example obtained by physical deposition or chemical deposition) or a film (for example laminated or held by electrostatic effect).

[0040] When the base element 21 is transparent, the reflector element 22 is, for example, arranged on all or part of the external face of the entry diopter or on all or part of the internal face of the exit diopter.

[0041] When the base element 21 is opaque, the reflective element 22 is, for example, arranged on all or part of the base element 21 (surface oriented towards the conductor 18).

[0042] The emission source 24 is capable of emitting at least one light beam, called useful beam F u , including information intended for the driver 18 or a passenger 19.

[0043] The light beam is, for example, in the visible wavelength range (380 nanometers to 700 nanometers).

[0044] Preferably, the emission source 24 comprises at least one screen. The screen is, for example, a liquid crystal display (LCD).

[0045] The optical block 26 is suitable for conveying the useful beam F u towards the reflector element 22 of the support 20 so that the reflector element 22 is capable of reflecting the useful beam F u to form a useful image IM in an observation window of the driver 18 in the driving position or of a passenger 19 of the vehicle 10. The useful image IM is a virtual image or a real image (real image possible depending on the optical block between the emission source 24 and the reflector element 22 and when the reflector element 22 also has a diffusing property).

[0046] Preferably, the optical block 26 is configured so that the useful beam F u arrives at the reflector element 22 at a predetermined point of incidence Pi with a predetermined angle of incidence ©i, the point of incidence Pi and the angle of incidence ©i being chosen so that the useful beam F ureflected on the reflector element 22 forms a useful image IM in an observation window of the driver 18 in the driving position or of a passenger 19 of the vehicle 10. The angle of incidence ©i is the angle between the axis of the beam and the normal N to the reflector element 22 at the point of incidence Pi of the useful beam F u on the reflector element 22.

[0047] The optical block 26 comprises at least one optic that is both reflective and diffusing, called diffusing mirror 30.

[0048] The diffusing mirror 30 is suitable for receiving the useful beam F u , and to reflect and diffuse it like a secondary emission source, that is to say a source which returns a light beam but without producing it.

[0049] Preferably, the diffusing mirror 30 is the only diffusing element of the optical block 26. In other words, the optical block 26 does not include an additional diffuser.

[0050] Preferably, the bidirectional reflectance distribution function, called BRDF (in English “Bidirectional Reflectance Distribution Function”), of the diffusing mirror 30 is constant on the surface of the secondary emission source seen from the observation window of the driver 18 or the passenger 19. This allows the useful image IM to have a homogeneous brightness.

[0051] Preferably, the reflection coefficient of the diffusing mirror 30 is greater than or equal to 90 percent, preferably strictly greater than 92 percent, advantageously strictly greater than 95 percent, ideally greater than or equal to 97 percent.

[0052] In the example illustrated by Figure 3, the diffusing mirror 30 is formed from a stack of superimposed layers. The stack of layers comprises in the following order at least: a substrate 32, a fixing layer 34 and a reflective layer 36. Optionally, the diffusing mirror 30 comprises at least one oxide layer 38 fixed on the reflective layer 36. In the specific example of Figure 3, the diffusing mirror 30 comprises two oxide layers 38.

[0053] The substrate 32 has a textured face 40 conferring the diffusing property to the diffusing mirror 30. By “textured face”, we mean a non-planar and non-smooth face.

[0054] The fixing layer 34 is fixed on the textured face 40 of the substrate 32, the reflective layer 36 being fixed on the fixing layer 34. Preferably, the textured face 40 of the substrate 32 is capable of diffusing an incident beam with a diffusion angle such that the useful image IM formed following the reflection of the useful beam F u on the reflector element 22 occupies a predetermined portion of the observation window of the conductor 18. Preferably, the textured face 40 of the substrate 32 is capable of diffusing an incident beam with a diffusion angle less than or equal to a predetermined value.

[0055] The predetermined value depends in particular on the type of head-up display considered, and the display constraints. For example, the predetermined value is 30 degrees, which allows for particularly directional diffusion. Alternatively, the predetermined value is 50 degrees, particularly for long-distance head-up displays.

[0056] In an exemplary implementation, the textured face 40 of the substrate 32 is formed from an arrangement of diffusing elements on said textured face 40.

[0057] Preferably, the diffusing elements are arranged isotropically. This avoids polarizing the useful beam F u and avoid reducing the reflection coefficient. In addition, having diffusing elements distributed homogeneously allows for rotationally symmetric diffusion.

[0058] Preferably, each diffusing element has at least two planes of symmetry.

[0059] Preferably, each diffusing element does not have coplanar surfaces at the macroscopic scale. This minimizes specular reflection and avoids the formation of hot spots (bright spots).

[0060] Preferably, the diffusing elements have a spherical shape. The diffusing elements are, for example, microbeads.

[0061] Alternatively, the diffusing elements are randomly arranged micropyramids. Alternatively or in addition, the diffusing elements are randomly sloped micropyramids.

[0062] In one example, the arrangement of scattering elements allows for Gaussian scattering.

[0063] The substrate 32 is, for example, made of metal, glass, or plastic.

[0064] The thickness of the substrate 32 is, for example, between 100 micrometers (pm) and 3 millimeters (mm). The thickness is defined in the stacking direction Z as illustrated in Figure 3.

[0065] The fixing layer 34 is suitable for fixing the reflective layer 36 to the substrate 32.

[0066] The fixing layer 34 is, for example, made of chrome or titanium. Such a fixing layer 34 allows the reflective layer 36 to be attached to the substrate 32. The thickness of the fixing layer 34 is, for example, between 1 nanometer (nm) and 100 nm.

[0067] The reflective layer 36 is capable of reflecting the useful beam F u The reflection coefficient of the reflective layer 36 is greater than or equal to 90 percent, preferably strictly greater than 92 percent, advantageously strictly greater than 95 percent, ideally greater than or equal to 97 percent.

[0068] The reflective layer 36 has, for example, been deposited by evaporation or sputtering.

[0069] The reflective layer 36 is, for example, made of aluminum or silver.

[0070] The thickness of the reflective layer 36 is, for example, between 10 nm and 3 pm.

[0071] The oxide layer 38 is fixed on the reflective layer 36. In one example, the stack is formed of several superimposed oxide layers 38. The oxide layer(s) 38 make it possible to increase the reflectivity of the reflective layer 36, and therefore of the diffusing mirror 30.

[0072] The thickness of each oxide layer 38 is, for example, between 10 nm and 3 pm.

[0073] The operation of the display device 16 will now be described.

[0074] Initially, the emission source 24 sends a light beam, called the useful beam F u , towards the optical block 26.

[0075] The diffusing mirror 30 of the optical block 26 diffuses and reflects the useful beam F u so that the useful beam F u is sent to the reflector element 22.

[0076] The reflector element 22 reflects the useful beam F uto form a useful image IM in an observation window of a driver 18 in the driving position.

[0077] Thus, the diffusing mirror 30, combining the properties of both a mirror and a diffuser, makes it possible to reduce the number of optics useful for routing a light beam onto the reflector element 22 of the support 20.

[0078] In particular, the configurations of Figures 4 to 6 illustrate the reduction in the number of optics (and therefore in volume and weight) provided by the display device 16 according to the invention compared to a display device of the state of the art. In particular, in the examples of Figures 4 and 6, the optical block 26 of the display device of the state of the art comprises a diffuser D1 and two mirrors M1 and M2, whereas in the display device 16 according to the invention, the diffuser D1 and the mirror M1 are replaced by the diffusing mirror 30. Similarly, in the example of Figure 5, the optical block 26 of the display device of the state of the art comprises a diffuser D1 and three mirrors M1, M2, M3, whereas in the display device 16 according to the invention, the diffuser D1 and the mirror M1 are replaced by the diffusing mirror 30.

[0079] Thus, the display device 16 allows the display of information useful for driving a vehicle 10, while remaining compact and easy to integrate into a vehicle 10. Those skilled in the art will understand that the embodiments and variants previously described can be combined to form new embodiments provided that they are technically compatible.

Claims

CLAIMS 1. Head-up display device (16) for a vehicle (10), comprising: a. a support (20) comprising a reflector element (22), b. an emission source (24) capable of emitting a light beam, called useful beam (F u ), and c. an optical block (26) suitable for conveying the useful beam (F u ) towards the reflector element (22) so that the reflector element (22) is capable of reflecting the useful beam (F u ) to form a useful image (IM) in an observation window of a driver (18) or at least one passenger (19) of the vehicle (10), the optical unit (26) comprising an optic having both a reflective property and a diffusing property, called a diffusing mirror (30), the diffusing mirror (30) being suitable for receiving the useful beam (F u ), and to reflect and diffuse it as a secondary emission source.

2. Device (16) according to claim 1, in which the bidirectional reflectance distribution function, called BRDF, of the diffusing mirror (30) is constant over the surface of the secondary emission source seen from the driver's (18) or passenger's (19) observation window.

3. Device (16) according to claim 1 or 2, in which the reflection coefficient of the diffusing mirror (30) is greater than or equal to 90 percent, preferably strictly greater than 92 percent, advantageously strictly greater than 95 percent.

4. Device (16) according to any one of claims 1 to 3, in which the diffusing mirror (30) is formed from a stack of layers including: a substrate (32), a fixing layer (34) and a reflective layer (36), the substrate (32) having a textured face (40) conferring the diffusing property to the diffusing mirror (30), the fixing layer (34) being fixed on the textured face (40) of the substrate (32), the reflective layer (36) being fixed on the fixing layer (34).

5. Device (16) according to claim 4, wherein the textured face (40) of the substrate (32) is formed from an arrangement of diffusing elements on said textured face (40).

6. Device (16) according to claim 5, in which the diffusing elements are arranged isotropically.

7. Device (16) according to claim 5 or 6, in which each diffusing element has at least two planes of symmetry, preferably the diffusing elements having a spherical shape.

8. Device (16) according to any one of claims 4 to 7, in which the diffusing mirror (30) comprises at least one oxide layer (38) fixed on the reflective layer (36).

9. Device (16) according to any one of claims 1 to 8, in which the diffusing mirror (30) is the only diffusing element of the optical block (26).

10. Vehicle (10) comprising a display device (16) according to any one of claims 1 to 9.

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