Lighting device and method, particularly for a target

Abstract

Title: Lighting Device and Method, Particularly for a Target The invention relates to a lighting device comprising: - a light source (2) producing a luminous flux; - a concentrator of the luminous flux (3) into a beam of light deflected specularly (31) integrated within a diffusely reflected light flux (32). Figure for the abstract: Fig. 3

Description

Title of the invention: Device and method for illuminating, in particular, a target technical field

[0001] The field of the invention is that of non-imaging optics, also called anidolic optics.

[0002] More specifically, the invention relates to the design and manufacture of lighting devices, in particular for illuminating a target

[0003] The invention finds particular application in a lighting device enabling the highlighting of a target, and in particular jewelry when it is on display. State of the art

[0004] He is known to create jewelry stands equipped with lighting means.

[0005] By way of example, the patent document published under US number 6,433,483 describes a lighting device comprising a housing for receiving a piece of jewelry, and lighting means presenting a plurality of light sources.

[0006] The light sources are positioned in contact with the jewelry, so that the light radiation they emit is directed directly towards the jewelry and passes through it.

[0007] This device also includes control means for turning on or off the light sources so that the light radiation emitted by the light sources illuminates randomly, or according to a precise pattern, different points of the jewel.

[0008] This results in a random propagation and refraction of light rays in the jewel, which causes a sparkling effect for a person looking at the jewel.

[0009] However, this type of device has a major drawback.

[0010] Indeed, the device, and more specifically the housing for receiving the jewelry, must be designed according to the jewelry to be showcased.

[0011] In other words, in order to make all jewelry or all types of jewelry sparkle, the support is therefore designed according to each piece of jewelry.

[0012] This implies that there must be as many supports as there are jewels to be illuminated.

[0013] Furthermore, such a system limits the natural effect of the sparkle since the light sources are in contact with the jewel. The light sources are then visible to an observer who can thus know where the light radiation causing the sparkle originates. the jewelry, to the detriment of showcasing the jewelry or, at the very least, of its presentation.

[0014] Alternatively, lighting devices are known that employ a plurality of light sources positioned at a distance from the jewel to be illuminated, and lit successively to produce a scintillation effect.

[0015] This type of lighting device avoids being specific to a particular piece of jewelry, however the light sources are generally very visible, and produce a light diffusion around the illuminated target.

[0016] Means of concentrating the luminous flux from a light source can then be implemented, such as collimators, lenses, or reflectors. These means can take different forms depending on the desired light beam, and they can, for example, be parabolic, spherical, or have other shapes.

[0017] Nevertheless, regardless of the solution adopted, a light concentrator implementing a reflective surface generally induces losses due to light scattering resulting from a surface condition of the reflective surface which has a certain roughness.

[0018] As a reminder, a perfectly polished and smooth surface reflects light specularly. This means that the incident light rays are reflected in a precise direction, according to the law of reflection (angle of incidence equals angle of reflection). A good example of this type of surface is a mirror.

[0019] A rough surface, on the other hand, diffuses light. The light is scattered in many different directions, regardless of the angle of incidence. This occurs because the microscopic irregularities of the surface redirect the light rays randomly. An example of this type of surface is a sheet of paper.

[0020] A polished but slightly rough surface combines both types of reflection: specular and diffuse. When light strikes this surface, some of the light is reflected specularly, while some is diffused. In other words, some of the light is reflected as in specular light reflection. However, micro-irregularities on the surface cause a partial deviation of the light rays, resulting in a slight but not completely random dispersion of the light. The result is reflection in a predominant general direction (specular), but with slight diffusion of the light around this main direction due to surface imperfections.

[0021] This phenomenon results in a persistence of visibility of the light sources, or more generally a possibility that the origin of the light flux can be detected by a person observing the illuminated target, and a persistence of a luminous halo around the illuminated target.

[0022] In any event, a solution is sought which does not suffer from significant complexity in being implemented. Technical problem

[0023] The invention aims in particular to overcome these drawbacks of the prior art.

[0024] More specifically, the invention aims to provide a lighting device, particularly for a target, which produces little or no light disturbances resulting from light scattering of the luminous flux produced by the device.

[0025] The invention also aims to provide such a device which is not very complex, and simple to implement.

[0026] Another objective of the invention is to provide a device with a low manufacturing cost, or at least a reduced cost. Summary of the invention

[0027] These objectives, as well as others which will appear subsequently, are achieved thanks to the invention which relates to a lighting device comprising: - a light source producing a luminous flux; - a concentrator of the light flux into a beam of specularly deflected light integrated within a diffusely reflected light flux; characterized in that the lighting device comprises at least one flat reflective surface having a roughness of less than 10 nm, positioned integrally within the beam of specularly deflected light, and oriented so as to reflect at least a part of the beam of specularly deflected light by the concentrator of the light flux out of the diffusely reflected light flux.

[0028] Where the flat reflective surfaces have a roughness of less than 10 nm. Such a roughness is achieved in a relatively simple and uncomplicated way, for example by diamond turning.

[0029] Preferably, the flat reflective surface(s) have a roughness of less than 5 nm.

[0030] Even more preferably, the flat reflective surface(s) have a roughness of less than 1 nm. From 1 nm upwards, a polish can be described as "super polishing". Such "super" polishing of a flat reflective surface is particularly simpler and easier to perform than that of a parabolic surface located in a hollow.

[0031] Typically, the flat reflective surface(s) have a roughness of less than 0.5 nm. Optimal results can be obtained from such a roughness.

[0032] The flat reflective surface allows the specularly deflected beam of light to be reflected solely by "specular reflection". This results in a "perfect" beam of light that is not polluted by diffusely reflected light outside the area where this light is diffused.

[0033] The lighting device according to the invention thus produces little or no light disturbances resulting from light diffusion of the light flux produced by the device, while being simple to make and implement.

[0034] By the expression beam of light deflected specularly, it is more specifically envisaged that the light is refracted or reflected, as detailed below.

[0035] To solve the technical problem, it could have been considered to use a compound parabolic concentrator whose parabolic reflective surfaces would have been "super" polished, i.e. polished to have a roughness of less than 1 nm. However, super polishing a parabolic surface located in a difficult-to-access cavity is particularly complex and difficult to implement, which is not the case for a flat reflective surface.

[0036] According to a preferred feature, the light source is of the orthotropic type.

[0037] An orthotropic light source, also called a "Lambertian light source", allows illumination in all directions at equal intensity, and thus helps to optimize the obtaining of a specularly deflected beam of light which is homogeneous, promoting good illumination of the target to be illuminated.

[0038] Advantageously, the light flux concentrator comprises at least one parabolic reflective surface.

[0039] In this case, the use of a flat reflective surface, having undergone advanced polishing, or even "super" polishing, to redirect the deflected light beam specularly, is particularly advantageous because the parabolic reflective surface does not also need to undergo polishing or "super" polishing. It is therefore permissible to use such a parabolic reflective surface and benefit from its qualities without necessarily having to implement complex and costly polishing of this parabolic surface.

[0040] According to a preferred design, the light flux concentrator is a compound parabolic concentrator.

[0041] Preferably, the lighting device comprises a support having a receiving surface for a target to be illuminated, the support comprising an area to be illuminated positioned outside the flux of light reflected diffusely by the concentrator of the light flux.

[0042] According to a preferred embodiment, the light source and the light flux concentrator are oriented to emit the deflected light beam in such a way specular and the light flux reflected diffusely on the opposite side from where the area to be illuminated is located.

[0043] According to one envisaged embodiment, the flat reflective surface is mounted movable, and the lighting device includes an actuator configured to move the flat reflective surface 4.

[0044] This allows the direction of the beam of light deflected specularly by the flat reflective surface to be changed.

[0045] Advantageously, the lighting device comprises: - at least one actuator for the flat reflective surface; - electronic processing means controlling the actuator(s), to modify a position of the flat reflective surface.

[0046] This allows the direction towards which at least part of the light beam deflected specularly is reflected by the flat reflective surface.

[0047] The invention also relates to a lighting method comprising: - a stage in the production of a luminous flux; - a step of concentrating the light flux into a beam of light deflected specularly integrated within a flux of light reflected diffusely; characterized in that a target to be illuminated is positioned outside the diffusely reflected light flux, and in that it includes a step of redirecting at least part of the specularly deflected light beam towards the target to be illuminated by positioning a flat reflective surface having a roughness of less than 10 nm integrally in the specularly deflected light beam.

[0048] According to a preferred feature, during the concentration step, at least one parabolic reflective surface is used.

[0049] Advantageously, during the concentration step, a compound parabolic concentrator is implemented.

[0050] According to a preferred embodiment, the target to be illuminated is located opposite a side towards which the beam of light is emitted specularly and the flux of light is reflected diffusely. Brief description of the drawings

[0051] Other features and advantages of the invention will become more apparent upon reading the following description of various preferred embodiments of the invention, given by way of illustrative and non-limiting examples, and the accompanying drawings, among which: • [Fig.1] [Fig.1] is a schematic representation of the light emission produced by a compound parabolic concentrator associated with a light source; • [Fig.2] [Fig.2] is a schematic representation illustrating the principle redirection of a beam of light deflected specularly by a flat reflective surface that has undergone "super" polishing; • [Fig.3] [Fig.3] is a schematic representation of a device lighting of a target, according to the invention, implementing the aforementioned redirection principle. Detailed description

[0052] With reference to [Fig.3], a lighting device is shown.

[0053] According to the present embodiment, this lighting device is designed to illuminate a target. It comprises a support 1 on which a target to be illuminated 11 must be positioned.

[0054] More specifically, the support 1 has a receiving surface 10 for the target to be illuminated. This support 1 defines an area to be illuminated 12.

[0055] By way of example, according to one conceivable embodiment, the area to be illuminated 12 may correspond to the imprint of the target to be illuminated 11 on the receiving surface 10.

[0056] According to another conceivable embodiment, the lighting device takes the form of a simple lighting system and does not include a support.

[0057] Still referring to [Fig. 3], the lighting device also includes: - a light source 2 producing a luminous flux; - a luminous flux concentrator 3; - a flat reflective surface 4.

[0058] According to the present embodiment, the light source 2 is of the orthotropic type. The light source 2 is, for example, formed by a light-emitting diode.

[0059] As illustrated in Figures 1 to 3, the light flux concentrator 3 is coupled to the light source 2 in order to capture and concentrate the light flux it produces.

[0060] According to the present embodiment, the light flux concentrator 3 is a compound parabolic concentrator, known by the English acronym CPC ("Compound Parabolic Concentrator"). It thus comprises at least one parabolic reflective surface 30. More precisely, the light flux concentrator 3 is a micro compound parabolic concentrator.

[0061] According to another conceivable embodiment, the luminous flux concentrator 3 could be formed by lenses or a collimator or comprise flat reflective surfaces.

[0062] In the case where the light flux concentrator 3 includes at least one reflective surface, then the light from the specularly deviated light beam 31 is more precisely reflected by the reflective surface or surfaces, while in the case where the light flux concentrator 3 is formed by an optical lens, then the light from the specularly deviated light beam 31 is more precisely refracted by the optical lens.

[0063] The light flux concentrator 3 concentrates the light flux into a beam of light deflected specularly 31.

[0064] The light flux concentrator 3 also produces a diffusely reflected light flux 32, and the specularly deflected light beam 31 is integrated into the diffusely reflected light flux 32. In other words, the diffuse light reflected by the light flux concentrator 3 envelops the light reflected specularly by said light flux concentrator 3.

[0065] Indeed, the luminous flux concentrator 3 comprises at least one reflective surface which has a roughness greater than or equal to 10 nm.

[0066] With more specific reference to [Fig.1], the compound parabolic concentrator can be defined by the parabolas C'-C having focus A and D-D' having focus B. With the orthotropic light source 2 at AB, this results, for perfect parabolic surfaces, in a cone of light of a solid angle 0 defined by the lines BD and AC: the beam of light is reflected specularly 31.

[0067] Even if the parabolic surfaces are polished to a roughness of 10 to 20 nm (obtained by known manufacturing methods, for example, turning with a diamond tool), the micro-irregularities 300 of the surface generate a scattering that is then visible at the output of the compound parabolic concentrator. A primary beam of light is obtained, which is very intense, and a secondary beam of light is also obtained: the diffusely reflected light flux 32, with a much larger solid angle 0'. As a result, an observer located within the solid angle 0' of the lighting device, but outside the solid angle 0, can see the origin of the primary light beam.

[0068] By way of example, a compound parabolic micro-concentrator has an opening between D and C with a diameter of less than 2 mm, for a depth of approximately 4 mm. Superpolishing such a micro-concentrator therefore presents a particularly significant challenge.

[0069] As mentioned previously, and with reference to Figures 2 and 3, the lighting device includes at least one flat reflective surface 4.

[0070] For example, this flat reflective surface 4 corresponds to a glass mirror.

[0071] The shape of the flat reflective surface 4, or flat reflective surfaces 4, can be selected in order to produce suitable illumination.

[0072] For example, the shape of a flat reflective surface 4 can be a geometric shape such as a disk, a rectangle, or even, without limitation, that of a star.

[0073] The lighting device may comprise a single flat reflective surface 4, or a plurality of flat reflective surfaces 4.

[0074] This flat reflective surface 4 has a roughness of less than 10 nm, preferably less than 5 nm, even more preferably less than 1 nm, and typically less than 0.5 nm.

[0075] A roughness of less than 10 nm offers a good efficiency ratio with respect to the ease of production of such a reflective surface.

[0076] Below 5 nm, the performance of the flat reflective surface 4 increases to reduce the phenomenon of light diffusion.

[0077] From Inm, it can be considered that a limit has been reached from which the diffusion phenomenon is no longer visually discernible without optical equipment.

[0078] From a roughness of 0.5 nm, optimal results are achieved.

[0079] According to an alternative embodiment, the roughness must be less than one thousandth of the wavelength emitted by the light source.

[0080] The flat reflective surface 4 thus produces only a specular reflection of the incident light rays, or tends only to produce such a specular reflection.

[0081] The flat reflective surface 4 is positioned integrally in the beam of light deflected specularly 31.

[0082] This flat reflective surface 4 is oriented so as to reflect the beam of light deflected specularly 31 by the concentrator of the light flux 3 towards the area to be illuminated 12.

[0083] The flat reflective surface 4 produces, by reflection of the specularly deflected light beam 31 (which can be described as the primary beam of specularly reflected light), a secondary beam of specular light 4L

[0084] It is conceivable that the flat reflective surface 4 is oriented so as to reflect only a part of the light beam deflected specularly 31 by the light flux concentrator 3 towards the area to be illuminated 12.

[0085] It is also conceivable, according to other embodiments, that the lighting device comprises a plurality of flat reflective surfaces 4 positioned entirely within the beam of light deflected in a specular manner 31.

[0086] Furthermore, it is equally conceivable that the plurality of flat reflective surfaces 4 refers the beam of light towards the area to be illuminated 12, or a plurality of areas to be illuminated, typically of the type of the area to be illuminated 12.

[0087] With reference to [Fig.2], the association of the light flux concentrator 3 of the type compound parabolic concentrator with the planar reflective surface 4 extending throughout the entire specularly deflected light beam 31, makes it possible to simulate a perfectly polished compound parabolic concentrator 40 which would not produce light disturbances by diffusion.

[0088] As illustrated in [Fig.3], the area to be illuminated 12 is positioned outside the diffusely reflected light flux 32 by the light flux concentrator 3.

[0089] Indeed, with reference to figures 2 and 3, the area to be illuminated 12 is located in the part of the secondary beam of specular light 41, called the posterior part 410, which is located outside the flux of diffusely reflected light 32.

[0090] According to the embodiment illustrated by [Fig.3], the light source 2 and the light flux concentrator 3 are oriented to emit the specularly deflected light beam 31 and the diffusely reflected light flux 32 on the opposite side of the area to be illuminated 12.

[0091] More specifically, according to an orthogonal projection on an axis extending from left to right on the [Fig.3], the specularly deflected light beam 31 is emitted from right to left, from the light flux concentrator 3, while the target to be illuminated 12 is located to the right of the light flux concentrator 3 along the axis, the secondary specular light beam 41 going from left to right along this axis.

[0092] Still with reference to [Fig.3], the lighting device includes a part, called the emission part 5, from which the secondary beam of specular light 41 emerges to illuminate the target to be illuminated 11.

[0093] According to the present embodiment, the emission part 5 houses the light source 3, the light flux concentrator 3 and the flat reflective surface 4. For example, the emission part 5 may include a chamber in which the light source 3, the light flux concentrator 3 and the flat reflective surface 4 are fixed.

[0094] This chamber is advantageously provided with a coating that absorbs the light spectrum, such as a matte black paint.

[0095] In the emission part 5, the flat reflective surface 4 is held in position by an arm 42.

[0096] The emission part 5 has an aperture 51 through which the secondary beam of specular light 41 exits. As an indication, this aperture 51 may have a height of about two millimeters.

[0097] This opening 51 also forms a mask which can limit, at least partially, the passage of other undesirable light fluxes.

[0098] The lighting device also includes a longitudinal part 6 which extends from the emitting part 5 to the support 1.

[0099] The longitudinal part 6 has a proximal surface 61 near which the secondary beam of specular light 41 extends.

[0100] The secondary beam of specular light 41 is notably grazing this proximal surface 61.

[0101] Thanks to the design of the lighting device, no stray light, or at least very little stray light, illuminates the proximal surface 61.

[0102] The lighting device can be integrated into different types of objects.

[0103] For example, the lighting device can be integrated into a display stand or into a showcase, in particular display cases or showcases of jewellers for which the target to be illuminated may be a piece of jewelry.

[0104] The lighting device can also be integrated into a container, such as a jewelry box, but also a briefcase or luggage.

[0105] Such a container comprises a box and a lid movablely mounted on the box between an open position and a closed position. In this case, the emission part 5 can be formed in a rim of the lid and / or a rim of the box.

[0106] According to conceivable embodiments, the lighting device may comprise a plurality of assemblies each comprising a light source 2, a light flux concentrator 3 and at least one flat reflective surface 4 positioned integrally in the beam of light deflected specularly 31 by the light flux concentrator 3 of the assembly.

[0107] Each assembly is spaced from the other assemblies so as to be able to illuminate the target to be illuminated 11 from different angles.

[0108] For example, a display stand comprising a base can integrate along its perimeter a plurality of assemblies, and in particular a plurality of emission parts as described above.

[0109] According to another example, the perimeter of a container lid can be provided with a plurality of emission parts.

[0110] The lighting device includes electronic processing means, such as a computer, configured to control these different assemblies.

[0111] A typical parameterization may consist of producing distinct and point illuminations by each of the sets to create the illusion of a flicker of the target to be illuminated.

[0112] As mentioned previously, one or more flat reflective surfaces 4 are positioned integrally in the beam of light deflected specularly 31.

[0113] It is conceivable that this or these flat reflective surfaces 4 may be mounted movable, for example, by means of their arm 42.

[0114] To this end, in one conceivable embodiment, the lighting device includes at least one actuator, such as an electric motor, for the flat reflective surface 4, or for each flat reflective surface 4, or for a plurality of flat reflective surfaces 4.

[0115] The actuator(s) are then integrated into the device.

[0116] The actuator(s) are also configured to allow a controlled movement of the flat reflective surface(s) 4.

[0117] This mobility can be used to adjust the position, size and shape of the area to be illuminated 12.

[0118] The electronic processing means can be configured to be able to control the actuator(s), and modify the position of the flat reflective surfaces 4 in order to adjust this position, size and shape of the area to be illuminated 12.

[0119] In the case where the device employs a plurality of flat reflective surfaces 4, it is conceivable that these flat reflective surfaces 4 may be oriented to illuminate several targets, and / or several areas 12 of the same target. Thus, it is possible, with a single lighting device, to construct an elaborate scenography, for example in a museum setting with one or more works of art.

[0120] The device described above implements a lighting method of a target to be illuminated 11, according to the invention. The technical means of the lighting device described above are applicable to the method described below.

[0121] This process includes a step of producing a luminous flux. According to the present embodiment, this is a luminous flux produced by an orthotropic light source.

[0122] The method also includes a step of concentrating the light flux into a specularly deflected beam of light 31 integrated within a diffusely reflected light flux 32. During the concentration step, a compound parabolic concentrator is implemented, which includes at least one parabolic reflective surface 30.

[0123] The method also includes a step of redirecting at least a part of the specularly deflected light beam 31 back to the target to be illuminated 11.

[0124] This redirection step is carried out by positioning a flat reflective surface 4 having a roughness of less than 10 nm, preferably less than 5 nm, even more preferably less than 1 nm, and typically less than 0.5 nm, entirely within the beam of light deflected specularly 31.

[0125] During this redirection step, the target to be illuminated 11 is positioned outside the diffusely reflected light flux 32.

[0126] In this way, the target to be illuminated 11 is illuminated by the secondary beam of specular light 41.

[0127] As a reminder, this secondary beam of specular light 41 results from the "specular" reflection, on the flat reflective surface 4, of the beam of light deflected in a specular manner 31 (which can also be called the "primary" beam of light reflected in a specular manner) from the step of concentrating the light flux.

[0128] Finally, as illustrated by [Fig.3], during the implementation of the method, the target to be illuminated 11 is located on the opposite side towards which the beam of light deflected specularly 31 and the flux of light reflected diffusely 32 is emitted. This helps to mask the origin of the secondary beam of specular light 41.

[0129] The design of the lighting device and the lighting method makes it possible to render invisible the origins of the secondary beams of specular light 41, without involving a complex and costly manufacturing process such as would have been the case with a "super" polishing of compound parabolic concentrators.

Claims

Demands

1. Lighting device comprising: - a light source (2) producing a luminous flux; - a concentrator of the luminous flux (3) into a beam of specularly deflected light (31) integrated within a diffusely reflected light flux (32); characterized in that the lighting device comprises at least one flat reflective surface (4) having a roughness of less than 10 nm, positioned integrally within the beam of specularly deflected light (31), and oriented so as to reflect at least a part of the beam of specularly deflected light (31) by the concentrator of the luminous flux (3) out of the diffusely reflected light flux (32).

2. Lighting device according to the preceding claim, characterized in that the light source (2) is of the orthotropic type.

3. Lighting device according to any one of the preceding claims, characterized in that the luminous flux concentrator (3) comprises at least one parabolic reflective surface (30).

4. Lighting device according to the preceding claim, characterized in that the luminous flux concentrator (3) is a compound parabolic concentrator.

5. Lighting device according to any one of the preceding claims, characterized in that it comprises a support (1) having a receiving surface (10) for a target to be illuminated (11), the support (1) comprising an area to be illuminated (12) positioned outside the flux of light diffusely reflected (32) by the concentrator of the light flux (3).

6. Lighting device according to the preceding claim, characterized in that the light source (2) and the light flux concentrator (3) are oriented to emit the specularly deflected light beam (31) and the diffusely reflected light flux (32) opposite one side where the area to be illuminated (12) is located.

7. Lighting device according to any one of the preceding claims, characterized in that it comprises: - at least one actuator for the flat reflective surface 4; - electronic processing means controlling the actuator(s), to modify a position of the flat reflective surface 4.

8. Lighting method comprising: - a step of producing a luminous flux; - a step of concentrating the luminous flux into a beam of specularly deflected light (31) integrated within a beam of diffusely reflected light (32); characterized in that a target to be illuminated (11) is positioned outside the beam of diffusely reflected light (32), and in that it comprises a step of redirecting towards the target to be illuminated (11) at least a part of the beam of specularly deflected light (31) by positioning a flat reflective surface (4) having a roughness of less than 10 nm integrally within the beam of specularly deflected light (31).

9. Lighting method according to the preceding claim, characterized in that during the concentration step, at least one parabolic reflective surface (30) is used.

10. Lighting method according to the preceding claim, characterized in that during the concentration step, a compound parabolic concentrator is implemented.

11. Lighting method according to any one of claims 8 to 10, characterized in that the target to be illuminated (11) is located opposite a side towards which the beam of light deflected specularly (31) and the flux of light reflected diffusely (32) is emitted.

Images