Partially reflective blade, display device including such a blade, dashboard and head-up display device including such a display device

Abstract

The invention relates to a partially reflective sheet (1), comprising a transparent substrate (2) and then, in the following order from said transparent substrate (2): - a first layer (4) comprising a dielectric material, - a second layer (6) comprising silicon oxide, - a third layer (8) comprising the dielectric material, - a fourth layer (10) comprising silicon oxide, and - a fifth layer (12) comprising the dielectric material. According to the invention, the dielectric material comprises zirconium oxide or tantalum oxide. The invention also relates to a display device, a dashboard, and a head-up display device. Figure for the abstract: Fig. 1

Description

Title of the invention: Partially reflective blade, display device comprising such a blade, dashboard and head-up display device comprising such a display device

[0001] The present invention relates generally to the technical field of displaying information, in particular within vehicles (in particular motor vehicles).

[0002] It relates more particularly to a partially reflective blade, a display device comprising such a partially reflective blade, a dashboard and a head-up display device.

[0003] The dashboards of vehicles (in particular motor vehicles) are equipped with a combination of instruments allowing the driver of the vehicle to view information relating, for example, to the operation of the vehicle or to a route taken by this vehicle.

[0004] For example, the dashboard of the vehicle may include, on its rear face, a partially transparent blade making it possible to form a virtual image visible to the driver.

[0005] In order to guarantee optimal image quality and high energy performance, this partially transparent blade is for example obtained by the combination of a thin metallic layer and a structure of several layers comprising a dielectric material. This configuration makes it possible to obtain a reflectivity close to 30%.

[0006] However, the thin metallic layer absorbs the optical radiation passing through it, which reduces the quality of the projected image.

[0007] The aim of the present invention is therefore to improve the quality of the perceived image by overcoming the drawbacks resulting from the presence of the thin metallic layer.

[0008] More particularly, according to the invention, a partially reflective blade is proposed, comprising a transparent substrate then, in the following order from said transparent substrate: - a first layer comprising a dielectric material, - a second layer comprising silicon oxide, - a third layer comprising the dielectric material, - a fourth layer comprising silicon oxide, and - a fifth layer comprising the dielectric material.

[0009] According to the invention, the dielectric material comprises a zirconium oxide or a tantalum oxide.

[0010] Thus, advantageously according to the invention, the multilayer structure of the partially reflective blade makes it possible to obtain better reflectivity, of the order of 33%. Furthermore, the use of zirconium oxide or tantalum oxide is particularly advantageous from an industrial point of view because it is easy and inexpensive to obtain these two compounds. Furthermore, when these two components are in the form of a thin layer, they have a microstructure with few microcavities. This then gives the layer formed better mechanical strength.

[0011] According to the present invention, there is also provided a protective layer comprising silicon oxide positioned from the fifth layer.

[0012] Advantageously, this protective layer, positioned as a protective coating for the partially reflective blade, ensures chemical and environmental stability of the multilayer structure forming the partially reflective blade.

[0013] Other non-limiting and advantageous characteristics of the partially reflective blade according to the invention, taken individually or in all technically possible combinations, are the following: - the protective layer has a thickness of between 5 and 10 nanometers; - said dielectric material has a refractive index of between 2.05 and 2.4; - the first layer has a thickness of between 22 and 30 nanometers; - the second layer has a thickness of between 25 and 35 nanometers; - the third layer has a thickness of between 60 and 70 nanometers; - the fourth layer has a thickness of between 35 and 45 nanometers; - the fifth layer has a thickness of between 80 and 100 nanometers; - the transparent substrate comprises glass; - the transparent substrate comprises a polymeric material; - the transparent substrate comprises polymethyl methacrylate or polycarbonate; and - a coating layer comprising silicon oxide is also provided between the transparent substrate and the first layer.

[0014] The invention also relates to a display device intended to equip a motor vehicle, said display device comprising a partially reflective blade as introduced previously.

[0015] The invention also relates to a dashboard of a motor vehicle comprising a display device as introduced previously.

[0016] In this dashboard, the display device may comprise a display configured to produce a light beam in the direction of the partially retracted blade. bending, the partially reflective blade being positioned between a part of said dashboard and an observation area in such a way that the light beam is, in part, reflected in the direction of the observation area.

[0017] The invention finally relates to a head-up display device comprising an image generation device and a display device as introduced previously, said display device being configured to transmit towards the partially reflecting blade a light beam generated by said image generation device.

[0018] The description which follows with reference to the appended drawings, given as non-limiting examples, will make it clear what the invention consists of and how it can be implemented.

[0019] In the attached drawings:

[0020] [Fig-1] is a schematic view of a first embodiment of a blade by partially reflective in accordance with the invention,

[0021] [Fig.2] is a schematic view of a second embodiment of a partially reflective blade according to the invention,

[0022] [Fig.3] is a schematic view of a third embodiment of a partially reflective blade according to the invention,

[0023] [Fig.4] is a schematic view of a dashboard of a motor vehicle equipped with a partially reflective strip according to the invention, and

[0024] [Fig.5] is a schematic view of a head-up display device equipped with a partially reflective blade according to the invention.

[0025] As a preliminary point, it will be noted that the identical or similar elements of the different embodiments of the invention shown in the different figures will, as far as possible, be referenced by the same reference signs and will not be described each time.

[0026] In this description, the term "transparent" means that the element considered is formed from a material allowing more than 60% of the incident radiation in the visible spectrum to pass through, and preferably at least 70% of the incident radiation in the visible spectrum.

[0027] [Fig. 1] schematically represents a sectional view of a partially reflective blade 1 according to the invention. This partially reflective blade is for example integrated into a dashboard 20 ([Fig. 4]) of a motor vehicle or into a head-up display device 30 ([Fig. 5]) as will be described later.

[0028] As shown in [Fig.l], the partially reflective blade 1 comprises a multi-layer stack, successively comprising (from a layer forming the base of the partially reflective blade 1): - a transparent substrate 2 forming the base of the partially reflective blade 1, - a first layer 4 comprising a dielectric material and arranged above the transparent substrate 2, - a second layer 6 comprising silicon oxide (also noted SiO2) and arranged above the first layer 4, - a third layer 8 comprising the dielectric material and arranged above the second layer 6, - a fourth layer 10 comprising silicon oxide and arranged above the third layer 8, and - a fifth layer 12 comprising the dielectric material and arranged above the fourth layer 10.

[0029] Advantageously according to the invention, the partially reflective blade 1 therefore comprises a limited total number of layers but also a limited number of layers comprising the dielectric material. This configuration then makes it possible to guarantee good reflection and transmission properties of a light beam arriving on the partially reflective blade.

[0030] Preferably, the transparent substrate 2 here comprises glass. Alternatively, it may comprise a polymer material. This polymer material is, for example, polymethyl methacrylate (or PMMA according to the acronym usually used) or polycarbonate (or PC).

[0031] The transparent substrate 2 has a thickness of between 0.5 and 5 millimeters (mm). This ensures sufficient rigidity for the partially reflective blade 1.

[0032] Advantageously according to the invention, the dielectric material included in the first layer 4, the third layer 8 and the fifth layer 12 comprises a zirconium oxide (ZrO2) or a tantalum oxide (Ta2O5).

[0033] This dielectric material here has a refractive index, measured at a wavelength of 555 nanometers (nm), between 2.05 and 2.4. This range of values ​​for the refractive index then makes it possible to ensure good reflectivity of the partially transparent blade 1 while avoiding metal layers.

[0034] The second layer 6 and the fourth layer 10 comprising silicon oxide have a lower refractive index than the layers comprising the dielectric material. For example, the second layer 6 and the fourth layer 10 have a refractive index of between 1.4 and 1.7 (for a measurement at a wavelength of 555 nm).

[0035] In practice, in the partially reflective blade: - the first layer 4 has a thickness of between 22 and 30 nanometers, and / or - the second layer 6 has a thickness of between 25 and 35 nanometers, and / or - the third layer 8 has a thickness of between 60 and 70 nanometers, and / or - the fourth layer 10 has a thickness of between 35 and 45 nanometers, and / or - the fifth layer 12 has a thickness of between 80 and 100 nanometers.

[0036] Here, the partially reflective blade is for example formed by successive vacuum spraying of each of the materials concerned, so as to form each layer to the desired thickness. This thickness is for example between 0.5 and 5 mm.

[0037] Thus, this partially reflective blade makes it possible to obtain, by virtue of its layered structural characteristics, but also its material, refractive index and thickness characteristics, a uniform and high spectral reflectivity in the visible range. This reflectivity, in the visible range, is here between 25 and 40%, typically centered on 33%.

[0038] Advantageously, this configuration of the partially reflecting blade also leads to almost zero absorption of the light beam arriving on the partially reflecting blade.

[0039] A first advantageous example of the embodiment of the partially reflective blade is the following: - the transparent substrate 2 comprising glass and having a thickness of between 0.5 and 5 mm, - the first layer 4 with a thickness of 23 nm comprising zirconium oxide, - the second layer 6 with a thickness of 30 nm comprising silicon oxide, - the third layer 8 with a thickness of 60 nm comprising zirconium oxide, - the fourth layer 10 with a thickness of 40 nm comprising silicon oxide, and - the fifth layer 12 with a thickness of 83 nm comprising zirconium oxide.

[0040] This configuration makes it possible to obtain a substantially uniform spectral reflectivity in the visible, varying between 25 and 33%.

[0041] A second advantageous example of embodiment of the partially reflective blade is the following: - the transparent substrate 2 comprising glass and having a thickness of between 0.5 and 5 mm, - the first layer 4 with a thickness of 23 nm comprising tantalum oxide, - the second layer 6 with a thickness of 30 nm comprising silicon oxide, - the third layer 8 with a thickness of 60 nm comprising tantalum oxide, - the fourth layer 10 with a thickness of 40 nm comprising silicon oxide, and - the fifth layer 12 with a thickness of 85 nm comprising tantalum oxide.

[0042] This configuration makes it possible to obtain a substantially uniform spectral reflectivity in the visible, varying between 23 and 32%.

[0043] [Fig.2] represents a second embodiment of the partially reflective blade 1.

[0044] In this embodiment, as described for the first embodiment, the partially reflective plate 1 comprises the transparent substrate 2, the first layer 4, the second layer 6, the third layer 8, the fourth layer 10 and the fifth layer 12.

[0045] Advantageously, the partially reflective blade 1 also comprises a protective layer 14 positioned above the fifth layer 12. In other words, the protective layer 14 here forms the upper layer of the partially reflective blade 1.

[0046] This protective layer 14 comprises silicon oxide. The protective layer 14 has a thickness of between 5 and 10 nm.

[0047] Thus, this protective layer can be likened to a protective coating for the partially reflective blade. This then ensures chemical and environmental stability of the multilayer structure forming the partially reflective blade.

[0048] [Fig. 3] represents a third embodiment of the partially reflective blade 1.

[0049] In this embodiment, as described for the first embodiment, the partially reflective plate 1 comprises the transparent substrate 2, the first layer 4, the second layer 6, the third layer 8, the fourth layer 10 and the fifth layer 12.

[0050] Here, the partially reflective blade 1 also comprises a coating layer 3 positioned between the transparent substrate 2 and the first layer 4. This coating layer is used here as an intermediate layer. It makes it possible to guarantee good adhesion between the substrate and the other layers comprising the dielectric material. This coating layer is particularly advantageous in the case where the surface of the substrate has some irregularities or surface chemical properties unfavorable to the adhesion of the first layer 4.

[0051] This coating layer 3 comprises silicon oxide. It has a thickness of between 40 and 400 nanometers (nm).

[0052] In a variant not shown, the partially reflective blade may comprise, in this order: - the transparent substrate, - the coating layer, - the first layer, - the second layer, - the third layer, - the fourth layer, - the fifth layer, and - the protective layer.

[0053] In other words, in this variant, the partially reflective blade comprises both the protective layer above the fifth layer and the coating layer positioned between the transparent substrate and the first layer.

[0054] The partially transparent blade according to the invention is intended to be integrated into a display device installed in a motor vehicle.

[0055] For example, [Fig.4] represents a dashboard 20 provided with a display device comprising a partially reflective blade 1 according to the invention.

[0056] Here, the display device is formed of a display 22 integrated in the dashboard 20 and the partially reflective blade 1. The display 22 is configured to produce a light beam L in the direction of the partially reflective blade 1.

[0057] As shown in [Fig.4], the partially reflective blade 1 is interposed between an object (for example a part 24 of the dashboard 20 or a screen (not shown)) and an observation zone Z where an eye O of the driver of the motor vehicle is placed in the driving position.

[0058] In practice, the display 22 comprises for example a light source and a screen (not shown).

[0059] Here, the partially reflective blade is positioned in such a way that the transparent substrate 2 is opposite the part 24 of the dashboard 20 and that the fifth layer 12 (or the protective layer 14 in the case of the second embodiment described) is opposite the driver of the motor vehicle.

[0060] The partially reflecting blade 1 is furthermore oriented so that the light beam L is, in part, reflected in a direction D, in the direction of the observation zone Z so as to form a virtual image I for the eye O of the driver of the motor vehicle. The virtual image I contains information intended for the driver of the vehicle, for example in the form of regulatory symbols and / or a speed indicator and / or an engine speed indicator and / or a fault indicator.

[0061] [Fig. 5] represents a head-up display device 30 provided with a display device comprising a partially reflective blade 1 according to the invention.

[0062] The head-up display device comprises the partially reflective blade 1 placed in the driver's field of vision, an image generation device 32 adapted to generate a light beam and an image projection device 34 adapted to return, towards said partially transparent blade 1, the light beam generated by the image generation device 32. The display device is therefore here formed by the partially reflective blade 1 and the image projection device 32.

[0063] As shown in [Fig. 5], the partially reflective blade 1 is here positioned between the windshield 35 of the motor vehicle and the eyes of the driver. For example, the partially reflective blade is positioned in such a way that the transparent substrate 2 is turned towards the windshield 35 of the motor vehicle and that the fifth layer 12 (or the protective layer 14 in the case of the second embodiment described) is facing the driver of the motor vehicle.

[0064] The image projection device 34 is for example formed of mirrors and / or other optical elements, such as a lens for example.

[0065] The image generation device 32 comprises, for its part, a light source and a screen (not shown).

[0066] Thanks to the reflection of the light beam by the partially reflecting blade in the direction of the eyes of the driver of the motor vehicle, the head-up display device 30 is adapted to create a virtual image I in the field of vision of a driver of the vehicle, so that the driver can see this virtual image I and any information that it contains without having to look away.

Claims

Claims

1. Partially reflective plate (1), comprising a transparent substrate (2) then, in the following order from said transparent substrate (2): - a first layer (4) comprising a dielectric material, - a second layer (6) comprising silicon oxide, - a third layer (8) comprising the dielectric material, - a fourth layer (10) comprising silicon oxide, and - a fifth layer (12) comprising the dielectric material, characterized in that the dielectric material comprises a zirconium oxide or a tantalum oxide.

2. A partially reflective blade (1) according to claim 1, further comprising a protective layer (14) comprising silicon oxide positioned from the fifth layer (12).

3. Partially reflective blade (1) according to claim 2, wherein the protective layer (14) has a thickness of between 5 and 10 nanometers.

4. A partially reflective plate (1) according to any one of claims 1 to 3, wherein said dielectric material has a refractive index of between 2.05 and 2.

4.

5. Partially reflective blade (1) according to any one of claims 1 to 4, wherein: - the first layer (4) has a thickness of between 22 and 30 nanometers, - the second layer (6) has a thickness of between 25 and 35 nanometers, - the third layer (8) has a thickness of between 60 and 70 nanometers, - the fourth layer (10) has a thickness of between 35 and 45 nanometers, and - the fifth layer (12) has a thickness of between 80 and 100 nanometers.

6. A partially reflective blade (1) according to any one of claims 1 to 5, wherein the transparent substrate (2) comprises glass.

7. A partially reflective blade (1) according to any one of claims 1 to 5, wherein the transparent substrate (2) comprises a

8.

9.

10.

11.

12.

13. polymer material. Partially reflective blade (1) according to claim 7, wherein the transparent substrate (2) comprises polymethyl methacrylate or polycarbonate. Partially reflective blade (1) according to any one of claims 1 to 8, also comprising, between the transparent substrate (2) and the first layer (4), a coating layer (3) comprising silicon oxide. Display device intended to equip a motor vehicle, said display device comprising a partially reflective blade (1) according to any one of claims 1 to 9. Dashboard (20) of a motor vehicle comprising a display device according to claim 10. Dashboard (20) according to claim 11, wherein the display device comprises a display (22) configured to produce a light beam (L) towards the partially reflective blade (1), the partially reflective blade (1) being positioned between a part (24) of said dashboard (20) and an observation zone (Z) in such a way that the light beam (L) is, in part, reflected towards the observation zone (Z). Head-up display device (30) comprising an image generating device (32) and a display device according to claim 10, said display device being configured to transmit towards the partially reflecting blade (1) a light beam generated by said image generating device (32).

Images