Display device with semi-reflective surface element

Abstract

The invention relates to a display device (100) comprising: - a light source (101) capable of emitting light rays; - a semi-reflective surface element (110) arranged so as to receive the light rays (20) emitted by the light source, and to reflect a portion of the received light rays; wherein the semi-reflective surface element comprises: - a semi-reflective coating; and - an anti-condensation coating.

Description

Description Title of the invention: Display device with semi-reflective surface element

[0001] The present invention claims priority from French application 2400859 filed on 30.01.2024, the content of which (text, drawings and claims) is incorporated herein by reference. The present invention belongs to the field of display devices, in particular a display device with a semi-reflecting element capable of reflecting light rays from a light source. [2]It finds applications, in particular, but not exclusively, in a motor vehicle interior, for displaying information for the driver and / or passengers. [3] “Vehicle” means any type of vehicle such as a private, utility or heavy goods vehicle. [4]It is now common to equip the passenger compartment of a vehicle with one or more display devices in order to communicate information to the driver of the vehicle and / or the passenger. [5]It is particularly known to use hidden screens which project light onto a surface element, called a blade, which is visible to the driver and / or passenger of the vehicle. [6]Such a visible blade can be made with a mirror, capable of returning all the light rays received from the hidden screen of the lighting device. [7]A variant consists of using a semi-reflective surface element, which makes it possible to make an opaque panel of the lighting device, located behind the semi-reflective blade, visible. The opaque panel may in particular have a decorative function, visible when the hidden screen of the lighting device is deactivated in particular. [8]However, the use of such a semi-reflective blade in a lighting device with a hidden screen poses several disadvantages. [9]First, when the semi-reflective plate comprises a semi-reflective coating applied to one surface of a substrate, the opposite surface of the substrate is also visible, which may cause a double image to be displayed from the light rays projected by the screen. Such a double image deteriorates the display function of the display device.

[0010] Then, the condensation of water or organic matter on the surfaces of the semi-reflective blade, deteriorates on the one hand the optical performance of the semi-reflective blade and reduces its lifespan. [1 l]Finally, it is preferable to facilitate the cleaning of one or more surfaces of the semi-reflecting blade, especially as such surfaces have increasingly larger proportions, as well as to prevent the deposition of dust on the surface or surfaces of the semi-reflecting blade.

[0012] There is thus a need to overcome at least some of the drawbacks described above.

[0013] The present invention improves the situation.

[0014] To this end, a first aspect of the invention relates to a display device comprising: - a light source capable of emitting light rays; - a semi-reflecting surface element arranged so as to receive the light rays emitted by the light source, and to reflect part of the received light rays. The semi-reflective surface element includes: - a semi-reflective coating; and - an anti-condensation coating.

[0015] Thus, the invention allows the integration of an anti-condensation function in addition to the optical function performed by the semi-reflective surface element. The anti-condensation coating makes it possible on the one hand to improve the optical performance of the reflective surface element, and on the other hand to extend its service life.

[0016] According to embodiments, the semi-reflective coating may be arranged on a first surface of a substrate of the semi-reflective surface element and the semi-reflective surface element may further comprise an anti-reflective coating arranged on a second surface of the substrate, opposite the first surface.

[0017] This prevents the formation of a double image by the display device.

[0018] According to a first embodiment of the invention, the semi-reflective surface element is arranged so that the first surface is oriented towards the light source.

[0019] Such an embodiment makes it possible to merge the anti-reflective function and the anti-condensation function.

[0020] Alternatively, according to a second embodiment of the invention, the semi-reflecting surface element is arranged so that the second surface is oriented towards the light source.

[0021] According to embodiments, the anti-condensation coating may comprise a film comprising nanoscale protrusions.

[0022] Such a film makes it possible to take advantage of a physical phenomenon according to which the Gibbs barrier free energy, denoted AGc, which must be exceeded for heterogeneous nucleation of vapor condensation, increases significantly when the diameter of the nanostructures forming a solid surface on which condensation forms, decreases. It therefore allows the realization of an effective anti-condensation function.

[0023] Additionally, the film can be an organic film of the “moth eye” or “fly eye” type.

[0024] Such a film effectively delays or prevents the formation of condensation on the semi-reflective surface element.

[0025] In addition, the anti-reflective coating is achieved by the anti-condensation coating.

[0026] Thus, the anti-reflective function and the anti-condensation function are achieved by the same coating, which makes it possible to limit the number of coatings, and therefore to add functions to the semi-reflective surface element without degrading its optical function.

[0027] Additionally, the anti-condensation layer may include the film and an optically transparent adhesive.

[0028] An optically transparent adhesive, also called OCA for "Optical Clear Adhesive", has the advantage of being compatible with ceramic materials as well as organic materials.

[0029] According to embodiments, the semi-reflective surface element may further comprise an opaque surface arranged opposite an interior surface of the semi-reflective surface element, opposite an exterior surface opposite the light source.

[0030] Such an opaque surface is thus visible through the semi-reflective surface element when the light source is deactivated. The opaque surface can in particular fulfill an aesthetic function.

[0031] According to embodiments, the semi-reflective surface element may further comprise a lipophobic and / or hydrophobic coating forming an exterior surface of the semi-reflective surface element facing the light source.

[0032] Such a coating makes it easier to clean and / or wipe the outer surface of the semi-reflective surface element, by preventing the deposit of water, grease or dust in particular.

[0033] Additionally, the lipophobic and / or hydrophobic coating may include a layer of fluorine and / or silane.

[0034] This makes it possible to obtain an omniphobic outer surface.

[0035] Other characteristics and advantages of the invention will appear on examining the detailed description below, and the appended drawings in which:

[0036] [Fig 1] illustrates a sectional and side view of a display device according to embodiments of the invention;

[0037] [Fig 2a] illustrates a sectional and side view of a semi-reflective surface element of a display device according to a first embodiment of the invention;

[0038] [Fig 2b] illustrates a sectional and side view of a semi-reflective surface element of a display device according to a second embodiment of the invention;

[0039] [Fig 3a] illustrates a stack of a substrate and a semi-reflective layer;

[0040] [Fig 3b] illustrates a portion of a semi-reflective surface element with an anti-reflective coating, of a display device according to the first embodiment of the invention.

[0041] Figure 1 illustrates a sectional and side view of a display device 100 according to embodiments of the invention.

[0042] The display device 100 comprises a light source 101 capable of emitting light rays and arranged so as to emit the light rays towards an outer surface 111 of a semi-reflective surface element 110.

[0043] No restriction is attached to the light source, which may in particular be a pixelated light source comprising a plurality of individually activatable light elements. In this case, the light source 101 may form a screen, capable of emitting light rays 20 according to a pattern controllable by a control element of the display device 100, not shown in FIG. 1. In the following, it is considered for illustrative purposes only that the light source 101 is a screen.

[0044] The light elements may be electroluminescent elements such as light-emitting diodes. However, no restrictions are attached to the technology associated with the screen 101, according to the invention.

[0045] A "surface element" is an element extending mainly in two directions, that is to say that a third dimension called thickness, is at least three times, or even at least ten times or one hundred times, smaller than the other two dimensions. A planar surface element is shown in the figures: however, the semi-reflecting surface element 110 can be curved according to the invention.

[0046] The semi-reflecting surface element 110 is capable of reflecting a portion of the light rays 20 emitted by the screen 101, into a reflected beam 21.

[0047] The display device 100 comprises a frame 102 making it possible to define the arrangement of the screen 101 relative to the semi-reflecting surface element 110. The frame 102 is notably shaped so that the semi-reflecting element 110 is visible to an observer 10 located outside the display device 100, while the screen 101 is hidden, and is therefore not directly visible to the observer 10.

[0048] The semi-reflecting surface element 110 being semi-reflecting, it does not reflect all of the incident light rays 20: it is therefore to be distinguished from a mirror. Thus, a part of the light rays 20 forms the reflected beam 21, but another part of the light rays, not shown in FIG. 1, passes through the semi-reflecting surface element 110.

[0049] The frame 102 may comprise an opaque surface 103 arranged opposite an inner surface 112 of the semi-reflecting surface element 110, opposite the outer surface 111 described previously. The opaque surface 103 may have an aesthetic function, that is to say may have a given color and / or present a given pattern and / or be made of a given material, such as textile, wood, leather or any other material, so that the given color and / or the given pattern and / or the given material is visible through the semi-reflecting surface element 110, in particular when the light source 101 is off.

[0050] Figure 2a shows a sectional view of a structure of the semi-reflecting surface element 110 according to a first embodiment of the invention.

[0051] The sectional view is presented in an XZ plane, the Z axis representing the smallest dimension, i.e. the thickness of the semi-reflecting surface element 110. The semi-reflecting surface element 110 thus extends surface-wise in the X and Y directions. The ratio between the thickness along the Z axis and the dimension along the X axis is exaggerated, upwards, in FIG. 1, in order to be able to distinguish the different components of the structure of the semi-reflecting surface element 110. In practice, however, and as described previously, the thickness along the Z axis may be at least ten times smaller, or even at least one hundred times smaller than the dimension along the X axis and the dimension along the Y axis of the semi-reflecting surface element 110.

[0052] The semi-reflective surface element 110 comprises a transparent substrate 210, for example made of glass or plastic. The transparent substrate 210 may in particular comprise a plastic body 211, with one or two stiffening coatings on either side of the plastic body 211, in particular: - a first stiffening coating 212.1 forming a first surface of the substrate 210; and / or - a second stiffening coating 212.2 forming a second surface of the substrate 210.

[0053] There are no restrictions on the material of the stiffening coatings, which includes any rigid and transparent material.

[0054] When the body 211 is made of glass, the substrate 210 does not include any stiffening coating.

[0055] The semi-reflecting surface element 110 further comprises, according to the invention, a semi-reflecting coating 201, arranged on the first surface of the substrate 210. In the first embodiment, the semi-reflecting surface element 110 is arranged so that the first surface of the substrate 210 is oriented towards the outer surface 111 of the semi-reflecting surface element 110, i.e. towards the screen 101, the part 20 of the light rays being reflected by the semi-reflecting coating 201 before passing through the substrate 210.

[0056] No restriction is attached to the type of material or to the thickness of the semi-reflective coating 201, which may be a multi-layer structure comprising several layers of ceramics, arranged and shaped so as to produce constructive interferences making it possible to reflect a portion of the incident light rays 20 to form the reflected beam 21.

[0057] According to the invention, the semi-reflective surface element 110 may further comprise an anti-condensation coating 203. In the first embodiment, the anti-condensation coating 203 forms the inner surface 112 of the semi-reflective surface element 110, i.e. it is arranged opposite the second surface of the substrate 210, facing the opaque surface 103.

[0058] The anti-condensation coating 203 thus aims to prevent the formation of condensation on the interior surface 112 of the semi-reflective surface element 110.

[0059] The formation of condensation in fact leads to deterioration of visibility through the semi-reflective surface element 110, in particular in the area between the inner surface 112 and the opaque surface 103, an area which is little or not accessible for cleaning or wiping. Condensation can also lead to degradation of the semi-reflective surface element 110, thus reducing its service life.

[0060] According to the physical principle of heterogeneous nucleation, the Gibbs barrier free energy, denoted AGc, which must be exceeded for heterogeneous nucleation of vapor condensation, increases significantly when the diameter of the nanostructures forming a solid surface on which condensation forms decreases. In addition, Laplace forces appear under such conditions, i.e., when the diameter of the nanostructures is small, for example, below a given threshold.

[0061] Thus, according to embodiments of the invention, the anti-condensation coating 203 may comprise a film comprising protuberances of nanometric dimensions, i.e. with a diameter of less than 100 nanometers, or even less than 10 nanometers, the nanometric protuberances being similar to needles elongated in the Z direction perpendicular to the surface. Such nanometric protuberances are oriented towards the opaque surface 103, and thus make it possible to physically delay and reduce the formation of condensation on the interior surface 112. Such a film may be an organic anti-reflective film in the form of a fly's eye or moth's eye, also called "moth eye" in English. Such an organic film has the advantage of a low optical impact on the semi-reflective surface element 110.

[0062] The film can be integrated into the semi-reflective surface element 110 by adhesion using an optically transparent adhesive, or OCA in English for “Optical Clear Adhesive”, which has the advantage of being compatible with ceramic materials as well as organic materials.

[0063] The nanostructure of the anti-condensation coating 203 can be determined, by its dimensions, the nanostructure density and its material, so as to produce an anti-reflective coating. The advantage of forming an anti-reflective coating on the second surface of the substrate 210, opposite the first surface on which the semi-reflective coating 201 is arranged, will be better understood upon reading the description of FIGS. 3a and 3b.

[0064] Alternatively, when the anti-condensation coating 203 does not form an anti-reflective coating, the semi-reflective surface element 110 may further comprise an anti-reflective coating 202, made of ceramic for example, which, in the first embodiment, is arranged between the substrate 210 and the anti-condensation coating 203, the anti-condensation coating then being bonded to the anti-condensation coating by the OCA adhesive described previously. The anti-reflective coating 202 makes it possible to avoid reflection on the second surface of the substrate 210, responsible for the formation of a double image for the observer 10.

[0065] Advantageously, the semi-reflective surface element 110 may further comprise an anti-fingerprint coating 204 forming the outer surface 111 of the semi-reflective surface element 110 which is oriented towards the light source 101. Thus, in the first embodiment embodiment, the anti-fingerprint coating 204 may cover the semi-reflective coating 201 described previously.

[0066] The anti-fingerprint coating 204 makes the outer surface 111 easy to clean. Preferably, the anti-fingerprint coating 204 is omniphobic, and may in particular comprise a nanometric layer of fluorine and / or silane. For example, the anti-fingerprint coating 204 may comprise a nanometric-sized film comprising fluorine and silane: such a film is compatible with a ceramic coating, such as the semi-reflective coating 201 previously described, or the anti-reflective coating 202 in the second embodiment described below.

[0067] Fluorine is lipophobic while silane is hydrophobic, which allows the realization of an omniphobic coating. In addition, a nanometric dimension film is optically neutral and therefore has no impact from an optical point of view on the semi-reflective surface element 110.

[0068] Figure 2b shows a structure of the semi-reflecting surface element 110 according to a second embodiment of the invention.

[0069] In the second embodiment, the semi-reflecting surface element 110 is arranged so that the first surface of the substrate 210 is oriented towards the inner surface 112 of the semi-reflecting surface element 110, i.e. towards the opaque surface 103, the part 20 of the light rays thus being reflected by the semi-reflecting coating 201 after having passed through the substrate 210.

[0070] In the second embodiment, the anti-condensation coating 203 is thus bonded to the semi-reflective coating 201. In addition, the anti-fingerprint coating 204 covers the anti-reflective coating 202.

[0071] Thus, the invention allows the integration of numerous functions around the same substrate 210. In addition, the first embodiment has the advantage of allowing the anti-reflective and anti-condensation functions to be combined within the same coating 203.

[0072] The invention is further compatible with both plastic substrates and glass substrates, one or more stiffening coatings 212.1 -212.2 being provided if the substrate is plastic.

[0073] Furthermore, when the anti-condensation coating 203 comprises an OCA adhesive and the substrate 210 is glass, the anti-condensation coating 203 can perform an anti-shatter function.

[0074] Finally, when the semi-reflective surface element 110 comprises an anti-reflective coating 202 in addition to the semi-reflective coating 201, a duplication of the image displayed by the display device 100 is avoided.

[0075] Figures 3a and 3b illustrate the advantage of adding an anti-reflective layer on the second surface of the substrate 210, opposite the first surface on which the semi-reflective layer is arranged.

[0076] Figure 3a illustrates a stack of a substrate 210 and a semi-reflective layer 201 without an anti-reflective coating.

[0077] When an incident beam 300 arrives on the stack, the semi-reflecting layer 201 returns a portion of the incident beam 300 in the form of a first reflected beam 301, and another portion of the incident beam 300 is transmitted into the substrate 210 in the form of a transmitted beam 302. A portion of the transmitted beam is reflected by a second surface of the substrate opposite a first surface on which the semi-reflecting coating 201 is arranged, in the form of a second reflected beam 303. A portion of the second reflected beam 303 is transmitted to the outside of the stack, in the form of a second transmitted beam 304. Thus, the first reflected beam 301 and the second transmitted beam 304 come from the same incident beam, which causes the formation of a double image reflected by the stack.

[0078] Figure 3b illustrates a portion of a semi-reflective surface element with an anti-reflective coating 202, of a display device according to the first embodiment of the invention.

[0079] Figure 3b is thus the stack of figure 3a with in addition an anti-reflective coating 202 on the second surface of the substrate 210 opposite the first surface of the substrate 210 on which the semi-reflective coating 201 is arranged.

[0080] The addition of an anti-reflective coating 202 allows the entirety of the first transmitted beam 302, or more than 90% or even more than 95% of the first transmitted beam 302, to be transmitted as a third transmitted beam. 310, thus avoiding the formation of the second reflected beam 302 and therefore of the second transmitted beam 304 at the origin of the image splitting.

[0081] Note that Figure 3b corresponds to the first embodiment, in which the first surface of the substrate 210 is oriented towards the screen 101. However, a similar result is obtained in the second embodiment.

[0082] The present invention is not limited to the embodiments described above as examples; it extends to other variants.

Claims

Claims

1. A display device (100) comprising: - a light source (101) capable of emitting light rays; - a semi-reflecting surface element (110) arranged to receive the light rays (20) emitted by the light source, and to reflect a portion of the received light rays; wherein the semi-reflecting surface element comprises: - a semi-reflective coating (201); and - an anti-condensation coating (203).

2. A display device according to claim 1, wherein the semi-reflective coating (201) is arranged on a first surface of a substrate (210) of the semi-reflective surface element (110) and wherein the semi-reflective surface element further comprises an anti-reflective coating (202) arranged on a second surface of the substrate, opposite the first surface.

3. A display device according to claim 2, wherein the semi-reflective surface element (110) is arranged such that the first surface faces the light source (101).

4. A display device according to claim 2, wherein the semi-reflective surface element (110) is arranged such that the second surface faces the light source (101).

5. A display device according to one of the preceding claims, wherein the anti-condensation coating (203) comprises a film comprising nanometric protrusions.

6. A display device according to claim 5, wherein the film is an organic moth eye film.

7. A display device according to claim 2 and claim 6, wherein the anti-reflective coating is provided by the anti-condensation coating (203).

8. A display device according to one of claims 5 to 7, wherein the anti-condensation coating (203) comprises the film and an optically transparent adhesive.

9. Display device according to one of the preceding claims, further comprising an opaque surface (103) arranged opposite an inner surface of the semi-reflecting surface element (110), opposite an outer surface opposite the light source (101).

10. Display device according to one of the preceding claims, further comprising a lipophobic and / or hydrophobic coating (204) forming an outer surface of the semi-reflective surface element (110) facing the light source (101).

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