WO2015040288A1

WO2015040288A1 - Retro-reflective device improving the viewing of an image placed in front of a solar collector

Info

Publication number: WO2015040288A1
Application number: PCT/FR2014/000210
Authority: WO
Inventors: Badre Kerzabi
Original assignee: Sunpartner Technologies
Priority date: 2013-09-20
Filing date: 2014-09-18
Publication date: 2015-03-26
Also published as: FR3011125B1; FR3011125A1

Abstract

The invention relates to an optical device comprising at least: (a) a collector (5) of light energy from an external light source; (b) a transparent plate (1) arranged between said external light source and said collector, including a first surface positioned towards said external light source and made up of a first array (1a) of elementary dioptres (6), and a second surface positioned towards said collector and made up of a second array (1b) of elementary dioptres (7); (c) a plurality of reflectors (2) capable of redirecting, by specular reflection and regardless of the angle of incidence, all or part of the light emitted by said external light source and which passes through said first array (1a) of elementary dioptres (6) towards said second array (1b) of elementary dioptres (7); and (d) an image made up of pixel zones (3). Said device is characterised in that said reflectors (2) are arranged such that the incident light, for a first range of angles of incidence with the plane of the first array (1a) of elementary dioptres (6) and after optional reflection on said reflectors (2), reaches said collector (5), and in that for another range of angles of incidence with the plane of the first array (1a) of elementary dioptres (6) and after optional reflection on said reflectors (2), reaches said pixel zones (3) of the image.

Description

Catadioptric device improving the visualization of an image placed in front of a solar collector

Technical field of the invention

The present invention relates to optical devices that make it possible to display an image placed in front of a solar sensor while minimizing the energy performance losses of this sensor.

State of the art

The discrete visual integration of solar collectors is particularly useful in objects whose main function is to shield, at least partially, the sun's rays, such as in blinds, sunshades, parasols, shades and other . But a good visual and functional integration of solar collectors can also be useful in a wider range of supports, such as buildings, roofs, walls, tiles, glazing, transport vehicles, including boats and planes , billboards and advertising screens, electronic screens, clothing, and in general on any flat or non-planar support.

Solar collectors generally have a dark appearance, or contrast with the color of their environment. It is therefore necessary to integrate them visually in this environment as discreetly as possible. This need for visual integration needs to cover the solar collectors of a color or a semi-transparent image and of fairly good quality, while decreasing the performance of the solar collectors as little as possible. Patent WO / 2007/085721 is already known more particularly from an optical device composed of a lens array and an array of image zones placed opposite the lenses which enables an observer to visualize either the image reconstituted by the lenses. either the solar panel that is placed behind the device. The visualization of the image or solar panel then depends on the viewing angle with respect to the optical surface. When the lenses are semi-cylindrical, this alternation reiterates around every 25 °, which limits applications especially when they require to be able to observe the image continuously over a 90 ° angular range.

A first solution to this problem has already been given in the publications WO / 2013/057393 and WO / 2013/057394, which describe optical devices intended to increase both the total angular range of visualization of an image located on the surface. of a solar collector and the capture of solar rays by said sensor. These devices optics comprises a transparent plate which is disposed between the external light source and the solar collector and which has a plurality of slots (air slats). The first face of said transparent plate is planar or structured by a lens array, while the second face contains pixel areas of an image separated by transparency areas. The faces of each slot must be sufficiently polished so that these surfaces have the property of reflecting certain light rays that pass through the first face of the transparent plate. This optical reflection takes place thanks to the difference in refractive indices between the transparent material of the plate and the air contained in the slots. Part of the rays coming from a light source, in particular from the sun, are thus reflected on the walls of the slits and pass through the zones of transparency, whereas other solar rays pass directly through the zones of transparency without being reflected on the surface. slots. The amount of light that passes through the areas of transparency and reaches the solar collector is then greater than the amount of light that would have passed through the areas of transparency if the slits did not exist, which has the effect of increasing the efficiency of energy production of the device. The optical reflection on the walls of the slits also acts for the outgoing rays coming from the pixelated zones, which allows an observer to visualize all the pixelated zones, therefore an entire image, at much greater angles than with an optical system without slots. As a result, the visual integration of the device on a support is effective over a wider angular range than in the absence of slots.

This device nevertheless has several disadvantages.

A first technical problem lies in the physics of the phenomenon of total reflection of light at the interface between two optical media of different refractive indices. The reflection of the light is only total for angles of incidence of the light beam greater than a limit angle with respect to the normal to the diopter (42 ° for example for a glass / air interface). Thus, depending on the refractive index of the transparent plate, the geometric shape of the first face of this plate and the orientation of the air knives, there are angles of incidence for which the incident beam n is not reflected on the slots but crossing (Figure 1). This results in a decrease in the efficiency of the light sensor, which receives less light, and a reduction in the continuity of the angular ranges of vision of the image by an observer.

Several other problems are related to the fouling of the blades of air, the poor mechanical strength of the system and the difficulty of implementing its manufacturing process, which reduce the flatness of the diopter separating the transparent plate of the blade 'air. The incrustation of dust or dirt in the open air blades in front Before the optical system requires to prevent air circulation in the device and make it airtight, and thus to encapsulate the optical system with a protection plate, which however degrades the transparency of the device. The removal of material in the plate during the method of producing the air blades mechanically weakens the optical system, with the risk of rupture of the structured transparent plate or deformation by crushing the air knives. Now, by diminishing the pianety of the diopter, the total reflections which may occur therein are diminished accordingly.

Simultaneous resolution of the problems mentioned above would therefore make it possible to increase the performance of the solar collectors and to improve the continuity of the angular viewing ranges of the image by an observer, while considering methods of manufacturing such an optical system more. easy to implement.

The present invention therefore aims to remedy these drawbacks, by proposing the integration of reflectors instead of air blades in the optical device.

Objects of the invention

The object of the invention is constituted by an optical device and by its method of production.

The optical device according to the invention comprises at least:

(a) a sensor (5) of light energy from an external light source;

(b) a transparent plate (1) disposed between said external light source and said sensor, comprising a first face facing said external light source and constituted by a first network (1a) of elementary diopters (6), and a second face facing said sensor and consisting of a second network (1b) of elementary diopters (7);

(c) a plurality of reflectors (2) of height h and preferably arranged according to a network defined by a pitch (ρ, ρ '), and able to redirect by specular reflection and regardless of its angle of incidence all or part of the light emitted by said external light source and which passes through said first network (1a) of elementary diopters (6) towards said second network (1b) of elementary diopters (7);

(d) an image composed of pixel areas (3);

said device is characterized in that said reflectors (2) are chosen, in particular from the point of view of their height (h) and their spacing (ρ, ρ '), and from the point of view of their arrangement or orientation, so that the incident light, for a first range of angles of incidence with the plane of the first network (1 a) of elementary diopters (6) and after reflection or not on said reflectors (2), reaches said sensor (5), and for another range of angles of incidence with the plane of the first network (1a) of elementary dioptres (6) and after reflection or not on said reflectors (2), reaches said pixel areas (3) of the image.

The interface between two optical media of different refractive indices is called the diopter. Reflection is said to be specular when the incident ray gives rise to a single reflected ray. Ideally, the energy of the incident ray is totally in the reflected ray. The elementary term qualifies the smallest pattern of a network which, once repeated, constitutes the said network. The plane of the grating is defined by two non-collinear vectors, and the regular spacing between two identical points of two adjacent elementary patterns defines the pitch of the grating. Thus, the network is entirely described by the translation of the elementary pattern into two steps associated with the two vectors that form the plane of the network. According to some embodiments, the reflectors may be metallic, for example aluminum or silver, or colored, for example white, or made of carbon-based materials, for example graphene or graphite, and that they have their walls smooth or polished. As a result, these reflectors favor a specular reflection of the received light rather than diffuse reflection or absorption, the nature of the reflection closely depending on the quality of the interface. As soon as the size of the defects of the interface is less than or at the order of magnitude of the wavelength of the light received, the interface tends to become perfectly reflective.

According to a further alternative embodiment, said reflectors are semi-reflective, such as for example dichroic filters, and / or polarizing, such as reflective polarizers, and / or semi-transparent. In this way, only part of the light is reflected and the other part passes through and / or is absorbed by said reflector. This reflection and / or absorption can be restricted to a range of wavelengths of light, for example in the visible range, so that said reflectors also act as color filters.

According to the invention, said reflectors may be organized in a continuous or discontinuous network of elementary reflecting patterns, delimiting all types of shapes, in particular curved shapes, for example cylindrical, flat shapes, for example polygonal, prismatic or hexagonal. These elementary reflective patterns are oriented preferably orthogonally to the plane of the network of elementary diopters of the transparent plate.

According to a certain embodiment of the device according to the invention, the reflectors or the elementary reflective patterns have a height corresponding to the local thickness of the transparent plate, so that they intercept both the first network of elementary diopters and the second network of elementary diopters.

According to another embodiment, the reflectors or the elementary reflective patterns have a height less than the local thickness of the transparent plate. In this case they can intercept the first or the second network of elementary diopters, or even neither of the two networks.

Thus, whatever the angle of incidence of the light beam incident on the first network of elementary diopters, said beam can directly reach the second network of elementary diopters or be reflected one or more times on said reflective patterns before reach the second network of elementary diopters. In addition, the angles of redirection of the light are controlled, since the reflectors favor a specular reflection of the incident light. Moreover, by adjusting the size of the reflectors, it is possible to illuminate the light energy sensor continuously over an angular range of incidence of 90 °. When this angle range is adequately oriented with respect to the incident light beam, it is possible to increase the energy production efficiency of the system. By symmetry on the complementary angular range, the specular reflection on the walls of the reflectors also acts on the light rays coming from the pixel areas of the image, which allows an observer to visualize all the pixel zones, thus an entire image. , over a continuous 90 ° angle range. As a result, the visual integration of the device is effective over a wider angular range.

The elementary diopter arrays and the array of reflective patterns are contained in planes that are advantageously parallel to each other and defined by two non-collinear vectors, but may undergo a deformation such that these plane surfaces become curved surfaces, in particular in the case of a flexible catadioptric device.

The network of elementary reflective patterns is defined by two steps identical or very close to those defining the first elementary diopter array of the transparent plate, according to said two non-collinear vectors. As a result, the relative positioning of the elementary reflective patterns with respect to the elementary diopters of the first elementary diopter array is almost identical in all areas of the transparent plate. Therefore, the redirection of light, for a given angle of incidence, is also the same in any area of the transparent plate.

In a particular embodiment of the optical device according to the invention, the network of elementary reflecting patterns is defined by a height h and by steps p, p ', the elementary diopters are lenses of radius of curvature R, and the plate transparent present at the level of the valleys between two elementary dioptres a thickness t. In this configuration, the steps ρ, ρ 'are preferably between 20 μm and 2 mm, the thickness t is preferably between R and 3 * R and the height h is preferably between 0.2xt and t, and the radius of curvature R is preferably between 0.5xp and P

According to selected embodiments, the elementary dioptres constituting said first elementary diopter array and the elementary dioptres constituting said second elementary diopter array are combinations

(a) flat surfaces;

(b) convex or concave, symmetrical or asymmetrical lenses;

(c) prisms.

As a result, in each of the elementary diopter networks constituting the two faces of the transparent plate, said elementary diopters have geometric shapes that may be identical or different.

According to different embodiments of the device, the image is fixed or animated and consists of a multitude of opaque and / or semi-transparent pixel areas that can be separated from one another by transparency zones, and said zones of Pixels contain printed pixels or electronic pixels generated by backlit, electroluminescent, or reflective components.

Said image can be positioned between said sensor and said second network of elementary diopters of the transparent plate, or downstream of the sensor, the term downstream referring to the direction of propagation of the light from the external light source to the device.

Said image can also be directly in contact with said sensor and / or said second network of elementary diopters of the transparent plate, or separated from these surfaces by a material of refractive index different from that of the plate transparent, such as the air.

The invention finds its main applications in the case where the light energy sensor is a solar collector of thermal, photovoltaic, chemical or mixed type, flat or curved, rigid or flexible.

According to a further variant embodiment of the device, said light energy sensor is composed of solid or semi-transparent active zones, joined or separated from each other by zones of transparency.

The sensor is directly in contact with the second network of elementary diopters of the transparent plate, or separated from this surface by a material of refractive index different from that of the transparent plate, such as for example air. It follows from this variant the possibility of reversing the relative positions of the image and the sensor relative to the transparent plate, especially when said sensor consists of active areas separated from each other by areas of transparency.

The transparent plate consists of a solid, liquid or gaseous transparent material, such as mineral glass, organic glass, air or a polymer of PA, PET or polycarbonate type, and can be flat or curved, rigid or flexible possibly colored in its mass, or colorless.

According to a further variant embodiment illustrated in FIG. 5, the transparent plate can be divided into at least two sub-plates of different refractive indices, the sub-plates being separated from each other by intermediate arrays of elementary diopters. As a result, the incident beam emitted by the external light source passes through at least three diopters before reaching the sensor or pixel area of the image. Advantageously, the last sub-plate (the one that is closest to the image) may consist of air, and the network of reflective patterns may be entirely located in said last sub-plate, which facilitates the method of production. of the device.

In a particular embodiment not shown, the first elementary diopter array and / or the second elementary diopter array and / or the intermediate array of elementary diopters are covered with a functional surface, for example antireflection, antifouling or anti -UV. According to a further alternative embodiment not shown, the image is illuminated on the front face by one or more light sources, most of the light propagates in the thickness of the transparent plate which acts as a guide for wave, or in an additional transparent plate placed upstream of the transparent plate, or downstream of the transparent plate for a back-light, the terms upstream and downstream referring to the direction of propagation of the light from the external light source towards the device. According to an exemplary method for manufacturing a part of the device composed of the transparent plate and the elementary reflective pattern network, the procedure is as follows:

(a) supplying a plurality of transparent substrates each having two opposite planar and polished faces

(b) depositing a thin layer of reflective material on one of the two flat and polished faces of a first transparent substrate

(c) one of the two plane and polished faces of a second transparent substrate is fixed on said layer of deposited reflective material

(d) the deposition and fixing steps are repeated so as to obtain a regular stack consisting of an alternation of transparent substrates and reflectors

(e) cutting said stack perpendicularly to the plane of the flat and polished faces of the assembled transparent substrates

(F) is added on the cut face of said stack a transparent molded substrate whose outer face is made of the first network of elementary diopters. Said transparent molded substrate can be produced according to two different methods. According to a first method, a layer of a transparent material is deposited on the cut face of said stack, and then the outer surface of said layer is molded to create the first elementary diopter array. According to a second method, a transparent pre-molded substrate is supplied directly, one of the faces of which is the first elementary diopter array and the other side is planar, and then the flat face of the pre-molded transparent substrate is fixed on the cut face. said stack.

In this manufacturing process, the fixing steps are performed by welding or gluing using an optical glue of refractive index advantageously identical to those of the transparent substrates supplied. All of the transparent substrates assembled together form the transparent plate of the device according to the invention. The molding can be carried out under UV irradiation using rollers or textured pads which print a network of shapes on a photosensitive liquid or semi-liquid polymer, or by stamping a solid transparent material.

figures

The invention will be better understood with the aid of its detailed description, in relation to the figures, in which:

Figure 1 shows schematically in cross section the structure of a device according to the state of the art;

- Figures 2a, 2b, 2c and 2d show schematically in cross section the structure of a device according to the invention for different angular ranges of incidence of the external light;

Figures 3a, 3b, 3c and 3d show schematically in cross section the structure of a first embodiment of the device according to the invention for different angular ranges of incidence of the external light;

FIGS. 4a, 4b and 4c represent devices for different geometries of the first elementary diopter array and FIG. 4d defines parameters specific to these devices;

Figure 5 shows schematically in cross section the structure of another alternative embodiment of the device according to the invention;

Figures 6a, 6b, 6c, 6d, 6e and 6f illustrate different steps of a manufacturing method according to the invention.

The figures are not to scale, the relative thicknesses of the components of the device being deliberately exaggerated to better reveal its structure.

detailed description

Referring to Figure 1, which corresponds to a schematic sectional view of a known device according to the patent WO / 2013/057393. It comprises a transparent plate 1 provided with slots 15 and disposed between an external light source and a light energy sensor 5. The first face of said transparent plate 1 is composed of a network 1a of elementary diopters 6 which are lenses, whereas the second face, plane, contains zones of pixels 3 and zones of transparency 4 of an image.

By way of example in FIG. 1, two angles of incidence and θ _{2 are represented} between an incident beam (16 ', 16 ") originating from an external light source and the normal one at the elementary diopters 6. incidences are between 25 ° and 50 °, the angle θι being smaller than the angle 6 ₂ . In the case of an incidence of angle θι between the light beam and the normal to the elementary diopter 6, the incident beam 16 'is entirely reflected on the walls of the slots 15 and the reflected beam 17' reaches a transparency zone 4 of the image. On the other hand, for an angle of incidence θ ₂ , a first fraction of the incident beam 16 "is reflected on the walls of the slots 15 in the form of a reflected beam 17", while another fraction is transmitted in the slots 15 to come out in the form of a transmitted beam 18. The reflected beam 17 reaches a transparency zone 4 of the image and therefore the sensor 5, while the transmitted beam 18 reaches a pixel zone 3 of the image . Thus, the sensor 5 receives only a part of the energy of the incident radiation, the other part being lost on a pixel area 3 of the image.

In Fig. 1, the incident light source is in a range of

i

between 0 ° and + 90 ° with respect to the normal at the elementary diopter 6 taking for reference the clockwise direction. An observer placed in a range of complementary angles not shown in FIG. 1, that is to say between 0 ° and -90 °, sees at certain angles and by symmetry with the normal at the elementary diopter 6, the light coming from an area of pixels 3 of the image and at other complementary angles the color of the sensor 5.

The known device according to Figure 1 therefore has the disadvantage of the discontinuity of the angular ranges of illumination of the sensor 5 on the one hand and observation of the pixel areas 3 of the image on the other hand. In other words, for some angles, the external light source reaches the pixel areas 3 of the image instead of the sensor 5, while the observer sees the sensor 5 instead of the image.

FIG. 2 illustrates several schematic cross-sectional views of a device according to the invention for different angular ranges of incidence of the external light, between 0 ° and 90 ° with respect to the normal at the elementary diopter 6. The device consists of a light energy sensor 5 from an external light source, an image composed of pixel areas 3 and transparency areas 4, and a transparent plate 1 containing an array of reflective patterns constituted by one or more reflectors 2. Said transparent plate comprises a first face oriented towards said external light source and constituted by a first network 1a of elementary diopters 6, and a second face oriented towards said sensor and constituted by a second network 1b of elementary dioptres 7. The elementary dioptres 6 consist of convergent lenses that meet at a valley 9 to form the d bucket 1a while the elementary dioptres 7 are planar. Said convergent lenses advantageously have their focal plane located in the plane of the network 1b of elementary dioptres 7. The image is located between the transparent plate 1 and the sensor 5, in direct contact with the second network 1b The reflectors 2 are oriented perpendicularly to the plane of the network 1a of elementary diopters 6 and intercept the two faces of the transparent plate 1 at a valley 9. Their height is therefore equal to the thickness of the plate. transparent 1.

Under an incidence θ ₃ between 0 ° and 25 °, as shown in Figure 2a. the incident beam 16, at the crossing of the elementary diopter 6, converges directly to an elementary diopter 7 of the second network 1b of elementary diopters 7, without being reflected on the reflectors 2. It then reaches a transparency zone 4 of the image and therefore the light energy sensor 5. Under an incidence θ ₄ between 25 ° and 50 °, as shown in Figure 2b. the incident beam 16 which passes through an elementary diopter 6 of the first network 1a of elementary diopters 6 is reflected on a wall of the reflector 2 before reaching a transparency zone 4 of the image. For an angle of incidence θ ₅ between 50 ° and 75 °, the incident beam 16 also undergoes specular reflection on the reflector 2, to reach a pixel area 3 of the image, as shown in Figure 2c. Above 75 °, at an angle of incidence θ ₆ shown in Figure 2d. the incident beam 16 is reflected a first time on the wall of a reflector 2 ', then redirected to a neighboring reflector 2 "which faces it to be reflected a second time In the end, the beam reaches the elementary diopter 7 located at a pixel area 3 of the image.

Thus, over a total angular range of 50 °, the device according to the invention makes it possible to redirect the incident beam 16 by reflection on one or more reflectors 2 and this whatever the angle of incidence of the beam on the surface of the reflector 2. In particular, for angles of incidence between 25 ° and 50 ° relative to the normal to the elementary diopter 6, the beam is entirely redirected towards the sensor 5, which was not the case in the known device according to the state of the art presented in FIG. 1. However, there exist in the device according to the invention angular ranges between 50 ° and 90 ° for which the incident beam 16 does not reach the sensor 5 but the zones pixels 3 of the image, which reduces the efficiency of said sensor.

FIG. 3 schematizes a first variant embodiment of the device according to the invention seen in cross section and for different angular ranges of incidence of the external light, between 0 ° and 90 ° with respect to the normal at the elementary diopter 6. this variant, the reflectors 2 do not intercept the two faces of the transparent plate, but only the second network 1 b of elementary diopters 7.

Under an incidence β> between 0 ° and 25 °, as shown in Figure 3a. the incident beam 16, at the crossing of the elementary diopter 6 ', converges directly towards the elementary diopter 7' of the second network 1b of elementary diopters 7, without undergoing any Reflection on the reflectors 2. It then reaches the transparency zone 4 'of the image and therefore the sensor 5. At an incidence θ ₈ between 25 ° and 50 °, as shown in FIG. 3b, the incident beam 16 which passes through the elementary diopter 6 'of the first network 1a of elementary diopters 6 is reflected on a wall of the reflector 2' before reaching the transparency zone 4 'of the image. By symmetry with respect to the normal to the diopters 6, the specular reflection on the walls of the reflectors 2 also acts on the light rays from the pixel areas 3 of the image. Thus, a user sees through the diopter 6 "at an angle - θ ₈ the pixel area 3" of the image after reflection of the light rays on the second wall of the reflector 2 '. For an angle of incidence θ ₉ between 50 ° and 75 °, the height of the reflectors 2 is such that the incident beam 16, after passing through the elementary diopter 6 ', does not undergo reflection at the reflector 2' and continues its optical path in the transparent plate 1. The beam reaches the elementary diopter 7 "located between the reflectors 2 'and 2", at a region of transparency 4 "of the image, as shown in Figure 3c. Above 75 °, under an angle of incidence Θ10 shown in Figure 3d, the incident beam 16 passes through a portion of the transparent plate 1 without being reflected on the reflector 2 ', before being reflected on the reflector 2 "who faces him. By specular reflection, the beam reaches the elementary diopter 7 "at the region of transparency 4" of the image, before interacting with the light energy sensor 5.

This variant of the device according to the invention thus makes it possible to illuminate the sensor 5 continuously over an angular range of incidence of 90 ° and thus to increase the energy production efficiency of the system. By symmetry over the angular range between 0 ° and -90 ° and as illustrated in a particular case in FIG. 3b, the specular reflection on the walls of the reflectors 2 also acts on the light rays coming from the pixel zones 3 of the image, which allows an observer to view all the pixel areas 3, therefore an entire image, at much greater angles than with the optical system described in Figure 2. As a result, the visual integration of the device on a support is effective over a wider angular range than with a device whose height of the reflectors 2 equals the thickness of the transparent plate 1. Moreover, in all the embodiments shown diagrammatically in FIGS. 2 and 3, the reflectors 2 are positioned at the inter-lenses, that is to say aligned with the valleys 9 of the elementary diopters 6. Such a positioning has the effect of symmetrizing the viewing angles of the zones of pix 3 and the illumination angles of the sensors 5 relative to the normal to the elementary diopters 6. Nevertheless, said receivers 2 may be offset from the valleys 9 of the elementary diopters 6, which has the sole effect of modifying the continuity of these ranges. angular visualization or illumination, which are not in this cases more symmetrical to each other than normal to elementary dioptres 6.

According to three particular embodiments, and as shown in FIGS. 4a, 4b and 4c, the elementary diopters 6 of the first network 1a of elementary diopters 6 may consist of semi-cylindrical rectilinear lenses (FIG. 4a) or semi-cylindrical lenses. hexagonal spheres organized in the form of a cubic network (FIG. 4b) or in the form of a honeycomb (FIG. 4c). For the sake of clarity, all the diagrams of FIGS. 4a, 4b, 4c and 4d represent only a part of the device, namely the transparent plate 1 and the network 8 of elementary reflecting patterns 10.

In the embodiment of FIG. 4a, the elementary reflecting pattern 0 consists of a single reflector 2 in the form of a rectangular planar surface whose length is parallel to the axis of the rectilinear lens. In the two other embodiments, the elementary reflective pattern 10 is composed of a plurality of rectangular and plane reflectors 2, arranged to form the lateral surface of a square-based parallelepiped (FIG. 4b) or of a hexagonal prism. (Figure 4c). In these two types of networks, the same reflector 2 belongs to two different elementary reflective patterns (10 ', 10 ") via each of the two faces of said reflector 2. In all the embodiments of FIGS. 4a, 4b and 4c, the diopters elementary elements 7 of the second network 1b are planar and all of the elementary reflecting patterns 10 form a network 8.

The geometrical parameters of the elementary diopter arrays (6, 7) and the reflectors 2 seen according to the sectional planes represented by a double arrow in FIGS. 4a, 4b and 4c are indicated in FIG. 4d. The steps p, p '(p' being not shown) which describe the network 1a of elementary diopters 6 are advantageously the same as those which describe the network 1b of elementary diopters 7 and the network 8 of elementary reflective patterns 10. The lenses which form the elementary diopters 6 have a radius of curvature R. The distance t materializes the thickness of the transparent plate 1 at a valley 9 between two lenses, while the distance h defines the height of a reflector 2, c that is to say the size of the reflector 2 taken perpendicularly to the plane of the network 1a or 1b of elementary dioptres 6 or 7. In this case a rectangular reflector 2 oriented perpendicular to the plane of the network 1a or 1b of elementary diopters 6 or 7, it can be the width or the length of the rectangle.

According to the devices represented in FIGS. 4a, 4b and 4c, the pitches p, p 'are advantageously between 20 μm and 2 mm, without these limits being exhaustive, t is advantageously between R and 3xR and h is advantageously understood. between 0.2 * t and t. R is advantageously between 0.5 * p and p in the embodiments Figures 4a and 4b, and between 0.57 * p and p in the embodiment of Figure 4c.

As a concrete example, devices according to the invention have been made as shown in FIG. 4a with p = 1 mm, t = 730 μηη, h = 500 μm and with a radius of curvature R = 600 μm.

According to a further alternative embodiment illustrated in Figure 5. the transparent plate 1 is divided into two sub-plates (11,12) of different refractive indices. The first sub-plate 11 is separated from the second sub-plate 12 by an intermediate network 13 of elementary diopters 14 which are lenses. The first face of said transparent plate 1 also being composed of a lens array 1a, and the pitch of the two gratings 1a and 13 being the same, it follows that the first sub-plate 11 forms a network of biconvex lenses. In a particular advantageous case in terms of manufacturing process and shown in this figure, the height of the reflectors 2 is less than the thickness of the second sub-plate 12, which consists of air. Thus, the biconvex lenses constituting the first sub-plate 11 and which serve to focus the incident beam towards the zones of pixels 3 and the zones of transparency 4 of the image, are manufactured independently of the network of reflectors 2.

We now describe a manufacturing process for producing the optical device schematized in Figure 4a. The different steps of this process are illustrated in FIGS. 6a, 6b, 6c, 6d, 6e and 6f. In a first step (Figure 6a), supplying a first transparent substrate 19 'having two faces (19'a, 19'b) planar and polished to maximize specular reflection of light on their surfaces. Then deposited on the 19'b face of said first transparent substrate 19 'a thin layer of reflective material to form a first reflector 2' (Figure 6b). The third step consists in fixing on the first reflector 2 'the face 19 "a of a second transparent substrate 19" (FIG. 6c). The steps for depositing the reflective layer and for fixing a new transparent substrate 19 are repeated. successively several times so as to form a regular stack 20 consisting of an alternation of transparent substrates 19 and reflectors 2 (Figure 6d). The points-tinted in the figure symbolize the succession of continuous layers of transparent substrates 19 and reflectors 2. Said stack 20 is then cut perpendicular to the plane of the faces (19a, 19b) of the transparent substrates 19 assembled (Figure 6e). Finally, on the cut face 22 of said stack 20, a transparent molded substrate 21 is added whose external face consists of the first network 1a of elementary diopters 6 in the form of lenses (FIG. 6f). The optical device shown schematically in FIG. 4a is then obtained. Advantages of the invention

It follows from the foregoing that the invention achieves the goals set. It describes a device having optical characteristics for viewing an image on the surface of solar collectors, and which does not have the disadvantages of devices known to date.

Thanks to a better control of the angles of redirection of the light on the surface of the reflectors, the device object of the invention will make it possible to increase the performance of the solar collectors and to improve the angular ranges of continuous visualization of the image by an observer, while proposing an industrial manufacturing process easier to implement. The device object of the invention will also allow to overcome mechanical stresses and the risk of fouling of some known devices.

The invention is particularly adapted to the visual integration of solar collectors in blinds, sunshades, sunshades, parasols, shades, roofs, walls, tiles, glazing, transport vehicles , including boats and airplanes, advertising panels and screens, electronic displays, clothing, and in general on any imaged medium, including electronic images, and on any flat or curved surface.

List of references used in the figures:

1 Transparent plate 12 Second sub-plate

1a First network of diopters 13 Intermediate network of elementary elementary diopters

1b Second network of diopters 14 Elementary diopters of the intermediate elementary network

2 Reflectors 15 Slots

3 Pixel Zones in Image 16 Incident Beam

4 Transparency Zones of the Image 17 Reflected Beam

5 Light energy sensor 18 Transmitted beam

6 Elementary Diops of the First 19 Transparent Substrate

network

7 Elementary diopters of the second 19a First face of the transparent network substrate

8 Network of reflective patterns 19b Second side of transparent elemental substrate Valley 20 Stacking

Elemental Reflective Patterns 21 Molded Transparent Substrate

First sub-plate 22 Cut face

Claims

R E V E N D I C A T IO N S 1 - An optical device comprising at least:

(a) a sensor (5) of light energy from an external light source;

(c) a plurality of reflectors (2) having a height (h) and arranged according to a network defined by a pitch (ρ, ρ ') and able to redirect by specular reflection and regardless of its angle of incidence all or part light emitted by said external light source and which passes through said first network (1a) of elementary diopters (6) towards said second network (1b) of elementary diopters (7);

(d) an image composed of pixel areas (3);

said device being characterized in that said reflectors (2) are chosen with a height (h), a pitch (ρ, ρ ') and an arrangement such as incident light, for a first range of angles of incidence with the plane of the first network (1a) of elementary diopters (6) and after reflection or not on said reflectors (2), reaches said sensor (5), and for another range of angles of incidence with the plane of the first network (1a) of elementary diopters (6) and after reflection or not on said reflectors (2), reaches said pixel areas (3) of the image.

2 - Device according to claim 1, characterized in that said reflectors (2) are metallic, for example aluminum or silver, or colored, for example white, or made of carbon-based materials, for example graphene or graphite, and in that they have their smooth or polished walls.

3 - Device according to one of the preceding claims, characterized in that said reflectors (2) are semi-reflective, such as for example dichroic filters, and / or polarizing, such as reflective polarizers, and / or semi-transparent .

4 - Device according to one of the preceding claims, characterized in that said reflectors (2) are organized in a continuous or discontinuous pattern of patterns elementary reflectors (10) delimiting all types of shapes, in particular curved shapes, for example cylindrical, flat shapes, for example polygonal, prismatic or hexagonal, and in that said elementary reflecting patterns are preferably oriented orthogonally to the plane of the grating (1 a) of elementary dioptres (6) of the transparent plate (1).

5 - Device according to one of the preceding claims, characterized in that said reflectors (2) or the elementary reflective patterns (10) have a height corresponding to the local thickness of the transparent plate (1), so that they intercept the first network (1a) of elementary diopters (6) and the second network (1b) of elementary diopters (7).

6 - Device according to any one of claims 1 to 4, characterized in that said reflectors (2) or the elementary reflective patterns (10) have a height less than the local thickness of the transparent plate (1).

7 - Device according to one of claims 4 to 6, characterized in that the networks (1a, 1b) of elementary diopters (6,7) and the network (8) of elementary reflective patterns (10) are contained in plans advantageously parallel to each other and defined by two non-collinear vectors, but may undergo deformation such that these flat surfaces become curved surfaces, particularly in the case of a flexible catadioptric device.

8 - Device according to one of the preceding claims, characterized in that the elementary dioptres (6) constituting said first network (1a) of elementary diopters (6) and the elementary dioptres (7) constituting said second network (1 b) of elementary diopters (7) are combinations

(a) flat surfaces;

(b) convex or concave, symmetrical or asymmetrical lenses;

(c) prisms.

9 - Device according to one of claims 7, wherein said network (8) of elementary reflective patterns (10) is defined by a height h, and by two steps (p, p ') substantially identical to those defining the first network (1a) of elementary diopters (6) of the transparent plate, according to said two non-collinear vectors, the elementary diopters are lenses of radius of curvature R, the transparent plate present at the level of the valleys between two elementary dioptres (6) a thickness t, characterized in that the steps (ρ, ρ ') are preferably between 20 μητι and 2 mm, the thickness t is preferably between 3 and 3 * R and the height h is preferably between 0.2 * t and t, and the radius of curvature R is preferably between 0.5 * p and p.

10 - Device according to one of the preceding claims, characterized in that said image is fixed or animated and consists of a multitude of areas of pixels (3) opaque or semi-transparent which can be separated from each other by zones transparency (4), and said pixel areas (3) contain printed pixels or electronic pixels generated by backlit, electroluminescent, or reflective components.

11 - Device according to claim 10, characterized in that said image is positioned between said sensor (5) and said second network (1b) of elementary diopters (7) of the transparent plate (1), or downstream of said sensor ( 5), the term downstream referring to the direction of propagation of the light from the external light source to the device. 12 - Device according to claim 10 or claim 11, characterized in that said image is directly in contact with said sensor and / or said second network (1 b) of elementary diopters (7) of the transparent plate (1), or separated from these surfaces by a material of refractive index different from that of the transparent plate (1), such as for example air.

13 - Device according to one of the preceding claims, characterized in that said sensor (5) of light energy is a solar collector of thermal type, photovoltaic, chemical or mixed, flat or curved, rigid or flexible. 14 - Device according to one of the preceding claims, characterized in that said sensor (5) of light energy is composed of active areas full or semitransparent, contiguous or separated from each other by areas of transparency.

15 - Device according to one of the preceding claims, characterized in that the transparent plate (1) is made of a solid transparent material, liquid or gaseous, such as mineral glass, organic glass, air or a polymer of type PMMA, PET or polycarbonate, and in that it can be flat or curved, rigid or flexible, colored in its mass, or colorless.

16 - Device according to one of the preceding claims, characterized in that the transparent plate (1) is divided into at least two sub-plates of different refractive indices, said sub-plates being separated from each other by networks intermediates (13) of elementary wedges (14).

17 - Device according to claim 16, characterized in that the first network (1a) of elementary diopters (6) and / or the second network (1b) of elementary diopters (7) and / or the intermediate network (13) of diopters elements (14) are covered with a functional surface, for example anti-reflective, antifouling or anti-UV.

18 - Device according to one of the preceding claims, characterized in that the image (3) is illuminated on the front face by one or more light sources, most of the light propagates in the thickness of the plate transparent (1) which acts as a waveguide, or in an additional transparent plate placed upstream of the transparent plate (1), or downstream of the transparent plate (1) for rear-facing lighting, the terms upstream and downstream referring to the direction of propagation of light from the external light source to the device.

19 - Method of manufacturing the transparent plate (1) and the network (8) of elementary reflective patterns (10) of the device according to one of claims 1 to 15, characterized in that it comprises the steps of:

(a) supplying a plurality of transparent substrates (19) each having two planar and polished opposed faces (19a, 9b);

(b) depositing a thin layer of reflective material on one of two planar and polished faces of a first transparent substrate (19 ');

(c) affixing one of the two planar and polished faces of a second transparent substrate (9 ") to said layer of deposited reflective material;

(d) repeating the deposition and fixing steps so as to obtain a regular stack (20) consisting of an alternation of transparent substrates (19) and reflectors (2);

(e) cutting said stack (20) perpendicular to the plane of the flat and polished faces of the assembled transparent substrates (19);

(f) adding on the cut face (22) of said stack (20) a transparent substrate molded (21) whose outer face consists of the first network (1a) of elementary dioptres (6).