Head-up display device

Abstract

The present invention provides a. a transparent support (20) with an input optical interface (30) and an output optical interface (32); b. a reflective element (22) disposed on at least a portion of the external surface (30E) of the input optical interface (30); c. a reflecting element (22) disposed on at least a portion of the external surface (30E) of the input optical interface (30); I ), an information projection source (24) capable of emitting a light beam polarized along a primary polarization, called a primary polarization, towards the reflective element (22), and I The present invention relates to a head-up display device (10) comprising an information projection source (24) in which light having a certain incident angle reaches a reflective element (22) and defines an incident plane together with the reflective element (22), and the main polarization is a polarization contained in the incident angle, which is called P polarization, and the reflective element (22) has a reflectance for light having P polarization that is higher than the reflectance for light having a linear polarization perpendicular to the incident plane, which is called S polarization, over a range of incident angles including the above-mentioned incident angle.

Description

[Technical Field]

[0001] The present invention relates to a head-up display device, and further to a vehicle equipped with such a head-up display device. [Background technology]

[0002] A head-up display device typically comprises an information projection source capable of generating a light beam toward a transparent support, which comprises an input device and an output optical interface. The reflection of the light beam at each of the optical interfaces generates two virtual images: a useful image obtained by reflection at the input optical interface, and a spurious image obtained by reflection at the output optical interface. The spurious image, also known as a "ghost," affects the visibility of the useful image.

[0003] To limit the influence of spurious images and to improve the brightness of useful images, it is known to apply a semi-reflective treatment to the input optical interface to increase the reflection at the input optical interface, thereby reducing the amount of light transmitted to the output optical interface. Furthermore, an anti-reflective treatment can be applied to the output optical interface to limit the reflection at the output optical interface. However, such a technique cannot be applied when the transparent support is a windscreen. In fact, anti-reflective treatments applied to the external surface of a windscreen are not resistant to environmental conditions (weather, solar radiation, windscreen wiper blades).

[0004] Another known variation is to tint the transparent support to absorb the light directed towards the output optical interface instead of applying an anti-reflection treatment, however, for legal reasons, this technique is not applicable when the transparent support is a windscreen.

[0005] Another very well-known solution is to create wedges in the structure of a transparent support. Such a prismatic effect allows the reflection generated by the input optical interface to be superimposed on the reflection generated by the output optical interface. However, in the case of a windscreen, the combination of the windscreen (tilt angle, curvature) with the head-up display requires the manufacture of a specific windscreen for each model of vehicle. This makes the manufacture of the windscreen more complex. Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, there is a need for a head-up display device that is compatible with all types of transparent substrates, including vehicle windscreens, without increasing the complexity of manufacturing the transparent substrate, and that limits ghosting effects associated with spurious images. [Means for solving the problem]

[0007] To this end, the subject matter of this specification is a transparent support having an input optical interface and an output optical interface, each optical interface having an exterior surface and an interior surface opposite the exterior surface; a reflective element disposed on at least a portion of an external surface of the input optical interface; An information projection source (24) that makes it possible to emit a light beam polarized along a main polarization, called the incident beam, towards a reflective element, the incident beam reaching the reflective element at an angle of incidence and defining together with the reflective element a plane of incidence, the main polarization being the polarization contained in the plane of incidence, called P polarization. wherein the reflective element has a reflectivity for light having P polarization that is higher than the reflectivity for light having linear polarization perpendicular to the plane of incidence, called S polarization, over a range of incidence angles including the above-mentioned incidence angles.

[0008] According to other advantageous aspects, the device comprises one or more of the following characteristics, taken individually or according to all technically possible combinations: The reflective element has a reflectivity over the range of angles of incidence for light having P polarization that is higher than the reflectivity for light having a different polarization. The reflectivity of the reflective element for light having P polarization over a range of angles of incidence is 10 percent or greater, preferably 15 percent or greater, advantageously 20 percent or greater, and even more advantageously 40 percent or greater. The reflectivity of the reflective element for light having polarization other than P polarization is 10 percent or less, preferably 5 percent or less, over a range of angles of incidence. The range of angles of incidence is at least 20 degrees, preferably at least 40 degrees, preferably at least 60 degrees. The range of angles of incidence includes the Brewster angle for the input optical interface. The information projection source is configured to emit an incident beam at an angle of incidence selected such that a portion of the incident beam that is transmitted by the reflective element reaches the output optical interface at an angle substantially equal to the Brewster angle for the output optical interface. The reflective element includes a stack of dielectric layers. The transparent support is the windscreen of the vehicle, and the reflective element is advantageously arranged over the entire external surface of the input optical interface.

[0009] Furthermore, the present invention relates to a vehicle equipped with the above-mentioned head-up display device.

[0010] Other characteristics and advantages of the present invention will become apparent on reading the following description, made with reference to the following drawings, of embodiments of the invention given by way of limiting example only, in which: [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram of an example of a head-up display device. [Figure 2] FIG. 2 is a schematic perspective view of an example of the interior of a vehicle equipped with the head-up display device shown in FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0012] A head-up display system 10 is shown in FIGS.

[0013] As shown in Figure 2, the device 10 is suitable for incorporation into a vehicle 12. The vehicle may be, for example, a land, air or sea vehicle. A land vehicle may be, for example, a car (Figure 2) or a rail vehicle.

[0014] The device 10 is suitable for displaying information in the field of view of a driver 14 of a vehicle 12. The information is provided, for example, by instruments in the vehicle 12. As one example, the information relates to the speedometer of the vehicle 12, the energy consumption of the vehicle 12, an alarm related to the failure of a particular component of the vehicle 12, or navigation information (map, position, direction).

[0015] The apparatus 10 comprises a transparent support 20, a reflective element 22 and an information projection source 24.

[0016] The transparent support 20 has an input optical interface 30 and an output optical interface 32. The input optical interface 30 has an outer surface 30E and an inner surface 30I opposite the outer surface 30E. The output optical interface 32 has an outer surface 32E and an inner surface 32I opposite the outer surface. The outer surfaces 30E, 32E of each optical interface 30, 32 are oriented toward the outside of the optical interface 30, 32, i.e., toward the external environment (air). The inner surfaces 30I, 32I of each optical interface 30, 32 are oriented toward the inside of the optical interface 30, 32.

[0017] The transparent support 20 comprises at least one layer of transparent material between the input optical interface 30 and the output optical interface 32. The transparent material is, for example, glass or plastic.

[0018] In one embodiment, the transparent support 20 comprises multiple layers, where appropriate made of different transparent materials, between the input optical interface 30 and the output optical interface 32. The materials of these layers are, for example, glass, ethylene vinyl acetate (EVA) or polyvinyl butyral (PVB).

[0019] 1, the transparent support 20 comprises a first layer of glass 34, a second layer of PVB 36, and a third layer of glass 38. In this example, it is taken into account that the refractive indices of the materials of the different layers are substantially the same and do not cause additional spurious reflections at the interfaces.

[0020] The transparent support 20 is, for example, a panel also called a “combiner.” In one variant, the transparent support 20 is a windscreen, such as the windscreen of the vehicle 12, in which the device 10 is incorporated.

[0021] The reflective element 22, also called a reflective polarizer, is an element arranged on at least a portion of the external surface 30E of the input optical interface 30. The term "arranged" means that the reflective element 22 is applied to (and therefore in contact with) the external surface 30E of the input optical interface 30 and attached to the surface (by a mount, if appropriate). The reflective element 22 is thereby rigidly attached to the external surface 30E of the input optical interface 30. The reflective element 22 may be, for example, a coating or treatment (obtained, for example, by physical or chemical deposition) or a film (deposited or held by electrostatic effects, for example).

[0022] When the transparent support 20 is a vehicle windscreen, the reflective element 22 is advantageously arranged over the entire external surface 30E of the input optical interface 30, thereby making the reflective element 22 invisible to the user (no patch effect).

[0023] The reflective element 22 reflects an incident light beam F having a given range of wavelengths. i the incident beam F at the reflective element 22 i of the incident beam F i The incident angle θ of the polarized light i It can be reflected according to the

[0024] Incident beam F i The given range of wavelengths is, for example, the visible range (380 nanometers to 700 nanometers).

[0025] Incident beam F i The incident angle θ i is the beam axis and the incident beam F at the reflective element 22 i The incident point P i is the angle between the incident beam F and the normal N to the reflective element 22 at i axis and incident point P iThe normal N to the reflective element 22 at defines the plane of incidence. In the example shown in FIG. 1, the reference line is the plane of the drawing. In particular, the reflective element 22 reflects the incident beam F i , which allows for the reflection of at least a portion of the useful virtual image (useful beam F) that can be observed through the observation window. U ) to the output optical interface 32. i Where appropriate, the output optical interface 32 allows a portion of the beam transmitted by the reflecting element 22 to be reflected, resulting in a spurious virtual image (spurious beam F) that can be observed through the observation window. P (corresponding to

[0026] Hereinafter, linearly polarized light contained in the plane of incidence is also called P-polarized light, and linearly polarized light perpendicular to the plane of incidence is also called S-polarized light.

[0027] The reflective element 22 is optimized to reflect light with P polarization, such that the reflective element 22 has a higher reflectivity for P polarization than for light of different polarizations (S polarization, circular polarization, elliptically polarization) for a range of angles of incidence and for a given range of wavelengths.

[0028] Advantageously, the reflectivity of the reflective element 22 for a given angle of incidence and for a given wavelength for P-polarized light is selected to meet the transparency standards imposed on automobile windscreens (so that the reflective element 22 remains transparent and does not alter the driver's view), while being sufficiently high to make the "ghosting" effect negligible. To this end, the reflective element 22 has a signal-to-noise ratio between the useful beam and the spurious beam of 3 percent or less, preferably 1 percent or less, and advantageously 0.5 percent or less.

[0029] Preferably, the reflectivity of the reflective element 22 for P-polarized light, for an angle of incidence and for a given wavelength, is 10 percent or more, preferably 15 percent or more, advantageously 20 percent or more, advantageously 40 percent or more.

[0030] Advantageously, the reflectivity of the reflective element 22 for light of polarization other than P polarization, for an angle of incidence and for a given wavelength, is 10 percent or less, preferably 5 percent or less.

[0031] Advantageously, the range of angles of incidence is at least 20 degrees or more, preferably at least 40 degrees or more, preferably at least 60 degrees or more.

[0032] Preferably, the incident angle θ i The range includes the Brewster angle between the external environment (air) and the transparent support at the input optical interface (typically 56 degrees for an air-glass interface). The reflective element 22 is configured to create a Brewster angle-free effect, i.e., P-polarized light is not canceled out at the Brewster angle. Again, the Brewster angle is the angle of incidence of the incident beam at the optical interface; if the optical interface has P-polarized light, the beam will not reflect at the optical interface.

[0033] The reflective element 22 is, for example, a stack of dielectric layers.

[0034] The reflective element 22 is for example a polarizer having a specific reflectivity for polarized light P, as described in WO 1996 / 19347.

[0035] In particular, the reflective element 22 may comprise, for example, a multilayer polymer film having a positive stress optical coefficient (i.e., the refractive index increases along the direction of stretching when stretched) and including a layer of a crystalline or semi-crystalline naphthalene dicarboxylic acid polyester (e.g., 2,6-polyethylene naphthalate (“PEN”) or copolymers derived from ethylene glycol, naphthalene dicarboxylic acid, and other acids such as terephthalate) having an average thickness not exceeding 0.5 microns, and a layer of a second selected polymer (e.g., polyethylene terephthalate (PET) or co-PEN) having an average thickness not exceeding 0.5 microns.

[0036] In one alternative example, the reflective element 22 comprises a multilayer polymer film including a layer of a crystalline or semi-crystalline polyester (e.g., PET) having an average thickness not exceeding 0.5 microns and a layer of a second selected polymer (e.g., polyester or polystyrene) having an average thickness not exceeding 0.5 microns, the film stretching in at least one direction to at least twice its unstretched dimension in that direction.

[0037] In one embodiment, the reflective element 22 also has additional optical and / or mechanical properties imparted by at least one coating, such as heat protection, a color neutralization treatment, or an anti-scratch or anti-fog coating.

[0038] Additionally, or in one variation, the reflective element 22 is configured to be highly reflective (typically 50% or greater) in the visible range (at least near-visible: 700 μm to 1 μm) between P-polarized and S-polarized light, respectively, over a range of angles of incidence, and in this way, additional solar radiation can be rejected, among other things.

[0039] The information projection source 24 can emit a light beam that is incident on the reflective element 22. The incident beam F i conveys information, such as that described above.

[0040] The incident beam F emitted by the information projection source 24 i is a beam polarized according to a particular polarization called the principal polarization.

[0041] The primary polarization is the linear polarization contained in the plane of incidence and is called P polarization. Therefore, the primary polarization is different from S polarization, circular polarization, or elliptically polarization.

[0042] Incident beam F i The wavelength of is within the wavelength range given for the reflective element 22, typically in the visible range.

[0043] The information projection source 24 projects an incident beam F i is within the range of incidence angles θ defined above for the reflective element 22 i , and is configured to reach the reflective element 22.

[0044] Advantageously, the information projection source 24 is projected at an angle of incidence θ i Beam F is incident on reflective element 22 at i The beam transmitted by the reflective element 22 arrives at the output optical interface 32 at an angle substantially equal to the Brewster angle between the middle of the transparent support 20 and the external environment (air) (typically 33 degrees for a glass-air interface) or within an angular range of 10 degrees around the Brewster angle. Since the incident beam has P polarization, spurious reflections at the output optical interface 32 can be completely eliminated.

[0045] Now, the operation of the head-up display device 10 will be described.

[0046] Initially, the information projection source 24 sends an incident light beam polarized along a primary polarization to the reflective element 22. The incident beam F i is within a given wavelength range, typically in the visible range. The incident beam F i is the incident point P i The angle of incidence θ with respect to the normal N to the reflective element 22 at i reaches the reflective element 22 at

[0047] The reflective element 22 then reflects the incident beam F i The incident beam F is reflected to form a useful virtual image that can be viewed through the observation window. i has P polarization, and the angle of incidence of the beam on the reflective element 22 is θ i is within the range of the incident angle, so the reflected incident beam F i is the amount of light incident on an incident beam F with S polarization, or more generally with a polarization different from P. i is maximized for

[0048] The reflective element 22 reflects the incident beam F i also sends at least one other portion of the output optical interface 32.

[0049] Incident angle θ i Depending on the output optical interface 32, it may or may not reflect a portion of the beam transmitted by the reflective element 22 and the input optical interface 30, forming a spurious image that can be observed through the observation window.

[0050] However, in such a case, the amount of light reflected at the output optical interface 32 is relatively small. For example, for P-type primary polarization, the amount of light reflected at the output optical interface 32 is typically i On the other hand, when the primary polarization is S-type, the amount of light at the output optical interface 32 is i This is about 20 percent.

[0051] Furthermore, the angle of incidence is selected so that the beam transmitted by the reflective element 22 reaches the output optical interface 32 at an angle substantially equal to the Brewster angle between the transparent support 20 and the external environment (air), and the amount of light reflected at the output optical interface 32 is zero or almost zero (no spurious reflections).

[0052] Thereby, the head-up display device 10 can display information useful for driving in the driver's field of vision.

[0053] The combination of a reflective element 22 optimized to reflect light of an information projection source 24 emitting a light beam polarized along the P polarization, with P polarization, increases the amount of useful light reflected compared to the amount of spurious light reflected.

[0054] More specifically, for P-polarized light, the proportion of spurious light reflected is small compared to the proportion of useful light reflected, which makes the ghosting effect relatively negligible. Furthermore, for a specifically selected angle of incidence θ i For , the proportion of spurious light reflected is nearly zero or zero.

[0055] Furthermore, P polarization has the advantage that it can be used in polarized sunglass lenses, which in fact are conventionally constructed to transmit only P polarized light and reject other types of polarized light.

[0056] Furthermore, applying the reflective elements 22 to the transparent support 20 is easy to implement, since there is no need to change the structure of the support 20 or to change the internal layers or layers of the support 20. In particular, unlike in the case of prior art prism (wedge) solutions, the reflective elements 22 have the same configuration regardless of the structure (angle of incidence, curvature) of the transparent support 20. Thereby, the manufacturing of the transparent support 20 becomes less complicated, and the apparatus 10 is applicable to all kinds of transparent supports (both combiners and windscreens).

[0057] Those skilled in the art will understand that the above embodiments can be combined with each other where combinations are possible.

[0058] Furthermore, the above embodiment is also applicable to a prismatic configuration. In such a complementation, the output optical interface 32 is tilted ("wedge") relative to the input optical interface 30, superimposing spurious virtual images onto the useful virtual image. Such a complementation makes it possible to further limit ghosting effects, since the spurious images, already significantly weakened by the specific configuration of the device 10, are superimposed onto the useful image.

Claims

1. a. a transparent support (20) having an input optical interface (30) and an output optical interface (32), each optical interface (30, 32) having an exterior surface (30E, 32E) and an interior surface (30I, 32I) opposite the exterior surface (30E, 32E); b. a reflective element (22) disposed on at least a portion of the external surface (30E) of the input optical interface (30); c. Incident beam (F Ｉ an information projection source (24) capable of emitting a light beam polarized along a primary polarization called a primary polarization (F) towards the reflective element (22), wherein the incident beam (F Ｉ ) is the angle of incidence (θ ｉ ) which reaches the reflective element (22) and defines together with the reflective element (22) a plane of incidence, the main polarization being the polarization contained in the plane of incidence, called P-polarization. and the reflective element (22) reflects light having P polarization at the angle of incidence (θ ｉ A head-up display device (10) having a reflectance higher than the reflectance for light having a linear polarization perpendicular to the plane of incidence, called S polarization, over a range of angles of incidence including

2. 2. The apparatus of claim 1, wherein the reflective element has a reflectivity over the range of angles of incidence for light having P polarization that is higher than the reflectivity for light having a different polarization.

3. 3. The apparatus (10) of claim 1 or 2, wherein the reflectivity of the reflective element (22) for light having P polarization is greater than or equal to 10 percent over the range of angles of incidence.

4. An apparatus (10) as described in claim 1 or 2, wherein the reflectivity of the reflective element (22) for light having P polarization is 15 percent or greater over the range of incident angles.

5. An apparatus (10) as described in claim 1 or 2, wherein the reflectivity of the reflective element (22) for light having P polarization is 20 percent or greater over the range of incident angles.

6. An apparatus (10) as described in claim 1 or 2, wherein the reflectivity of the reflective element (22) for light having P polarization is 40 percent or greater over the range of incident angles.

7. 3. The apparatus (10) of claim 1 or 2, wherein the reflectivity of the reflective element (22) for light having a polarization other than P polarization is less than or equal to 10 percent over the range of angles of incidence.

8. An apparatus (10) as described in claim 1 or 2, wherein the reflectivity of the reflective element (22) for light having a polarization other than P polarization is 5 percent or less over the range of incident angles.

9. 3. The apparatus (10) of claim 1 or 2, wherein the range of angles of incidence is at least 20 degrees.

10. An apparatus (10) as described in claim 1 or 2, wherein the range of incident angles is at least 40 degrees.

11. An apparatus (10) as described in claim 1 or 2, wherein the range of incident angles is at least 60 degrees.

12. The apparatus (10) of claim 1 or 2, wherein the range of angles of incidence includes the Brewster angle for the input optical interface (30).

13. The information projection source (24) has an incident angle (θ ｉ ) with the incident beam (F Ｉ ), and the incident angle (θ ｉ 3. The apparatus (10) of claim 1, wherein the angle of incidence of the incident beam transmitted by the reflective element (22) is selected such that the portion of the incident beam transmitted by the reflective element (22) arrives at the output optical interface (32) at an angle substantially equal to a Brewster angle relative to the output optical interface (32).

14. The device (10) of claim 1 or 2, wherein the reflective element (22) comprises a stack of dielectric layers.

15. 3. The device (10) according to claim 1 or 2, wherein the transparent support (20) is a windscreen of a vehicle and the reflective element (22) is advantageously arranged on the entire external surface (30E) of the input optical interface (30).

16. A vehicle (12) comprising a head-up display device (10) according to claim 1 or 2.

Images