Lighting device and method, in particular for illuminating a target

Abstract

The invention relates to a lighting device, comprising: - a light source (2) producing a luminous flux; - a concentrator (3) for concentrating the luminous flux into a beam of specularly deflected light (31) integrated within a flux of diffusely reflected light (32).

Description

[0001] P3071 PC00

[0002] Lighting device and method, particularly for a target

[0003] Technical Field

[0004] The field of the invention is that of non-imaging optics, also called anidolic optics.

[0005] More specifically, the invention relates to the design and manufacture of lighting devices, particularly for illuminating a target.

[0006] The invention finds particular application in a lighting device enabling the highlighting of a target, and in particular jewelry when it is on display.

[0007] State of the art

[0008] He is known for creating jewelry displays equipped with lighting.

[0009] As an example, the patent document published under number US 6,433,483 describes a lighting device comprising a housing for receiving a jewel, and lighting means featuring a plurality of light sources.

[0010] The light sources are positioned in contact with the jewelry, so that the light they emit is directed straight towards the jewelry and passes through it.

[0011] This device also includes control means to turn the light sources on or off so that the light radiation emitted by the light sources illuminates randomly, or according to a precise pattern, different points of the jewelry.

[0012] This results in a random propagation and refraction of light rays within the jewelry, causing a shimmering effect for someone looking at the jewelry.

[0013] However, this type of device has a major drawback.

[0014] Indeed, the device, and more specifically the housing for receiving the jewelry, must be designed according to the jewelry to be showcased.

[0015] In other words, in order to make all jewelry or all types of jewelry sparkle, the stand is therefore designed according to each piece of jewelry.

[0016] This means that you need as many stands as there are pieces of jewelry to illuminate.

[0017] Furthermore, such a system limits the natural effect of the sparkle since the light sources are in contact with the jewelry. The light sources are then visible to an observer who can thus pinpoint the source of the light that makes the jewelry sparkle, to the detriment of showcasing the jewelry or, at the very least, its presentation.

[0018] 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 sparkling effect.

[0019] 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 diffused light around the illuminated target. P3071 PC00

[0020] Methods for concentrating the light beam from a light source can then be implemented, such as collimators, lenses, or reflectors. These methods can take different forms depending on the desired light beam, and they can, for example, be parabolic, spherical, or have other shapes.

[0021] 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.

[0022] 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.

[0023] 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. A sheet of paper is an example of this type of surface.

[0024] A polished but slightly rough surface combines both types of reflection: specular and diffuse. When light strikes this surface, some of it is reflected specularly, while some is diffused. In other words, some of the light is reflected as in specular reflection. However, micro-irregularities on the surface cause a partial deflection 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.

[0025] This phenomenon results in the continued visibility of light sources, or more generally, the possibility that the origin of the light flux can be detected by a person observing the illuminated target, and the persistence of a luminous halo around the illuminated target.

[0026] In any case, a solution is sought that does not suffer from significant complexity in its implementation.

[0027] Technical problem

[0028] The invention aims, in particular, to overcome these drawbacks of the prior art. More specifically, the invention aims to provide a lighting device, particularly for a target, that produces little or no light disturbances resulting from light scattering of the luminous flux produced by the device.

[0029] The invention also aims to provide such a device which is not very complex, and simple to implement.

[0030] Another objective of the invention is to provide a device with a low manufacturing cost, or at least a reduced cost. P3071 PC00

[0031] Summary of the invention

[0032] These objectives, as well as others that will emerge subsequently, are achieved through the invention, which relates to a lighting device comprising:

[0033] - a light source producing a luminous flux;

[0034] - 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.

[0035] Where flat reflective surfaces have a roughness of less than 10 nm. Such roughness is achieved in a relatively simple and uncomplicated way, for example by diamond turning.

[0036] Preferably, the flat reflective surface(s) have a roughness of less than 5 nm.

[0037] 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 significantly simpler and easier to achieve than that of a parabolic surface located in a hollow.

[0038] Typically, the flat reflective surface(s) have a roughness of less than 0.5 nm. Optimal results can be obtained from such a roughness.

[0039] 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 scattered.

[0040] 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.

[0041] The expression "spectrally deflected beam of light" more specifically refers to light being refracted or reflected, as detailed below.

[0042] To solve the technical problem, one could have considered using a compound parabolic concentrator whose parabolic reflective surfaces would have been "super" polished, that is, polished to have a roughness of less than 1 nm. However, superpolishing a parabolic surface located in a hard-to-reach cavity is particularly complex and difficult to implement, which is not the case for a flat reflective surface.

[0043] According to a preferred characteristic, the light source is orthotropic. An orthotropic light source, also known as a Lambertian light source, illuminates in all directions with equal intensity, and the P3071 PC00 thus helps to optimize the production of a specularly deflected, homogeneous beam of light, promoting good illumination of the target. Advantageously, the light concentrator includes at least one parabolic reflective surface.

[0044] 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 require polishing or "super" polishing. It is therefore possible to use such a parabolic reflective surface and benefit from its qualities without necessarily having to implement a complex and costly polishing process.

[0045] According to a preferred design, the light flux concentrator is a compound parabolic concentrator.

[0046] Preferably, the lighting device includes a support having a receiving surface for a target to be illuminated, the support including an area to be illuminated positioned outside the flux of light diffusely reflected by the concentrator of the light flux.

[0047] According to a preferred embodiment, the light source and the light flux concentrator are oriented to emit the deflected light beam specularly and the reflected light flux diffusely on the opposite side from where the area to be illuminated is located.

[0048] 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.

[0049] This allows the direction of the light beam to be changed, as it is deflected specularly by the flat reflective surface.

[0050] Advantageously, the lighting system includes:

[0051] - at least one actuator for the flat reflective surface;

[0052] - electronic processing means controlling the actuator(s), to modify a position of the flat reflective surface.

[0053] This allows for changing the direction towards which at least a portion of the specularly deflected light beam is reflected by the flat reflective surface. The invention also relates to a lighting method comprising:

[0054] - a stage in the production of a luminous flux;

[0055] - a step of concentrating the light flux into a specularly deviated beam of light integrated within a diffusely reflected beam of light; characterized in that a target to be illuminated is positioned outside the diffusely reflected beam of light, and in that it comprises a step of redirecting at least a portion of the specularly deviated beam of light towards the target to be illuminated by positioning a flat reflective surface having a roughness of less than 10 nm entirely within the specularly deviated beam of light. P3071 PC00

[0056] According to a preferred characteristic, during the concentration stage, at least one parabolic reflective surface is used.

[0057] Advantageously, during the concentration stage, a compound parabolic concentrator is implemented.

[0058] 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 diffusely reflected.

[0059] Brief description of the drawings

[0060] 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:

[0061] - [Fig. 1] Figure 1 is a schematic representation of the light emission produced by a compound parabolic concentrator associated with a light source;

[0062] - [Fig. 2] Figure 2 is a schematic representation illustrating the principle of redirecting a beam of light deflected specularly by a flat reflective surface that has undergone "super" polishing;

[0063] - [Fig. 3] Figure 3 is a schematic representation of a target lighting device, according to the invention, implementing the aforementioned redirection principle.

[0064] Detailed description

[0065] With reference to figure 3, a lighting device is shown.

[0066] According to this embodiment, this lighting device is designed to illuminate a target. It includes a support 1 on which a target to be illuminated 11 must be positioned.

[0067] More specifically, support 1 has a receiving surface 10 of the target to be illuminated. This support 1 defines an area to be illuminated 12.

[0068] As an example, according to one possible embodiment, the area to be illuminated 12 may correspond to the footprint of the target to be illuminated 11 on the receiving surface 10.

[0069] According to another possible embodiment, the lighting device takes the form of a simple lighting system and does not include a support.

[0070] With further reference to Figure 3, the lighting system also includes:

[0071] - a light source 2 producing a luminous flux;

[0072] - a luminous flux concentrator 3;

[0073] - a flat reflective surface 4.

[0074] According to this embodiment, the light source 2 is orthotropic. The light source 2 is, for example, a light-emitting diode. P3071 PC00

[0075] 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. According to this 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.

[0076] According to another conceivable embodiment, the luminous flux concentrator 3 could be formed by lenses or a collimator or comprises flat reflective surfaces.

[0077] In the case where the luminous 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(s), while in the case where the luminous 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.

[0078] The light flux concentrator 3 concentrates the light flux into a beam of light deflected specularly 31.

[0079] 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.

[0080] Indeed, the luminous flux concentrator 3 includes at least one reflective surface which has a roughness greater than or equal to 10 nm.

[0081] With more specific reference to Figure 1, the compound parabolic concentrator can be defined by the parabolas C'-C having focus A and DD' 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 Q defined by the lines BD and AC: the beam of light is reflected specularly 31.

[0082] Even if the parabolic surfaces are polished to a roughness of 10 to 20 nm (achieved by known manufacturing methods, for example, turning with a diamond tool), the micro-irregularities on the surface generate scattering that is then visible at the output of the compound parabolic concentrator. A very intense primary beam of light is obtained, as well as a secondary beam of light: the diffusely reflected light flux, with a much larger solid angle O'. Consequently, an observer located within the solid angle O' of the lighting device, but outside the solid angle O, can see the origin of the primary beam of light.

[0083] As an example, a compound parabolic micro-concentrator has an opening between points D and C with a diameter of less than 2 mm and a depth of approximately 4 mm. Superpolishing such a micro-concentrator is therefore particularly complex.

[0084] As mentioned previously, and with reference to Figures 2 and 3, the lighting device includes at least one flat reflective surface 4. P3071 PC00

[0085] For example, this flat reflective surface 4 corresponds to a glass mirror.

[0086] The shape of the flat reflective surface 4, or flat reflective surfaces 4, can be selected to produce suitable illumination.

[0087] 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.

[0088] The lighting device may comprise a single flat reflective surface 4, or a plurality of flat reflective surfaces 4.

[0089] 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.

[0090] A roughness of less than 10 nm offers a good efficiency ratio compared to the ease of production of such a reflective surface.

[0091] Below 5 nm, the performance of the flat reflective surface 4 increases to reduce the phenomenon of light diffusion.

[0092] From 1 nm upwards, a limit can be considered reached beyond which the scattering phenomenon is no longer visually discernible without optical equipment. Optimal results are achieved from a roughness of 0.5 nm upwards.

[0093] According to an alternative embodiment, the roughness must be less than one thousandth of the wavelength emitted by the light source.

[0094] 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.

[0095] The flat reflective surface 4 is positioned entirely within the beam of light deflected in a specular manner 31.

[0096] This flat reflective surface 4 is oriented so as to reflect the beam of light deflected specularly 31 by the light flux concentrator 3 towards the area to be illuminated 12.

[0097] The flat reflective surface 4 produces, by reflection of the specularly deflected beam of light 31 (which can be described as the primary beam of specularly reflected light), a secondary beam of specular light 41.

[0098] 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 concentrator of the light flux 3 towards the area to be illuminated 12.

[0099] 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 specularly 31.

[0100] 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.

[0101] Referring to Figure 2, the combination of the parabolic compound light concentrator 3 with the flat reflective surface 4 extending throughout the entire specularly deflected light beam 31 allows for the simulation of a perfectly polished parabolic compound concentrator 40 that would not produce light disturbances by diffusion. P3071 PC00

[0102] As illustrated in Figure 3, the area to be illuminated 12 is positioned outside the diffusely reflected light flux 32 by the light flux concentrator 3. Indeed, with reference to Figures 2 and 3, the area to be illuminated 12 is located in the part of the secondary specular light beam 41, called the posterior part 410, which is located outside the diffusely reflected light flux 32.

[0103] According to the embodiment illustrated by Figure 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 opposite one side where the area to be illuminated 12 is located.

[0104] More specifically, according to an orthogonal projection onto an axis extending from left to right in Figure 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.

[0105] With further reference to Figure 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.

[0106] 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. This chamber is advantageously provided with a coating absorbing the light spectrum, such as a matte black paint.

[0107] In the emission part 5, the flat reflective surface 4 is held in position by an arm 42.

[0108] 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.

[0109] This opening 51 also forms a mask which can limit, at least partially, the passage of other undesirable light fluxes.

[0110] The lighting device also includes a longitudinal part 6 which extends from the emitting part 5 to the support 1.

[0111] The longitudinal part 6 has a proximal surface 61 near which the secondary beam of specular light 41 extends.

[0112] The secondary beam of specular light 41 is notably grazing this proximal surface 61.

[0113] Thanks to the design of the lighting device, no stray light, or at least very little stray light, illuminates the proximal surface 61.

[0114] The lighting device can be integrated into different types of objects.

[0115] For example, the lighting device can be integrated into a display stand or showcase, particularly jewellers' displays or showcases where the target to be illuminated may be a piece of jewelry.

[0116] The lighting device can also be integrated into a container, such as a jewelry box, briefcase, or piece of luggage. P3071 PC00

[0117] Such a container comprises a box and a lid movable 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.

[0118] 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 entirely within the beam of light deflected specularly 31 by the light flux concentrator 3 of the assembly.

[0119] Each set is spaced from the other sets so that the target to be illuminated 11 can be illuminated from different angles.

[0120] For example, a display stand including a base can integrate along its perimeter a plurality of assemblies, and in particular a plurality of emission parts as described previously.

[0121] According to another example, the rim of a container lid can be provided with a plurality of emission parts.

[0122] The lighting system includes electronic processing means, such as a computer, configured to control these different assemblies.

[0123] A typical setup might involve producing distinct and spot illuminations by each of the sets to create the illusion of a flicker of the target to be illuminated.

[0124] As mentioned previously, one or more flat reflective surfaces 4 are positioned entirely within the beam of light deflected specularly 31.

[0125] It is conceivable that this or these flat reflective surfaces 4 may be mounted movably, for example, by means of their arm 42.

[0126] 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.

[0127] The actuator(s) are then integrated into the device.

[0128] The actuator(s) are also configured to allow controlled movement of the flat reflective surface(s) 4. This mobility can be used to adjust the position, size, and shape of the area to be illuminated 12.

[0129] The electronic processing means can be configured to control the actuator(s), and modify the position of the flat reflective surfaces 4 in order to adjust the position, size and shape of the area to be illuminated 12.

[0130] In cases where the system employs multiple flat reflective surfaces 4, it is possible for these flat reflective surfaces 4 to be oriented to illuminate several targets, and / or several areas 12 of the same target. Thus, it is possible to create an elaborate scenography with a single lighting system, for example, in a museum setting with one or more works of art. P3071 PC00

[0131] The device described above implements a method for illuminating a target 11, according to the invention. The technical means of the lighting device described above are applicable to the method described below.

[0132] This process includes a step of producing a luminous flux. In this embodiment, the luminous flux is produced by an orthotropic light source.

[0133] The process 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.

[0134] The process also includes a step of redirecting at least part of the specularly deflected light beam 31 back to the target to be illuminated 11.

[0135] 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.

[0136] During this redirection step, the target to be illuminated 11 is positioned outside the diffusely reflected light flux 32.

[0137] In this way, the target to be illuminated 11 is illuminated by the secondary beam of specular light 41.

[0138] 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.

[0139] Finally, as illustrated by Figure 3, during the implementation of the process, 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.

[0140] The design of the lighting device and the lighting process makes it possible to render the origins of the secondary beams of specular light 41 invisible, without involving a complex and costly manufacturing process such as would have been the case with a "super" polishing of compound parabolic concentrators.

Claims

P3071 PC00 DEMANDS 1. Lighting system comprising: - a light source (2) producing a luminous flux; - a concentrator of the light 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 light 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) of 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 beam of light deflected specularly P3071 PC00 (31) and the diffusely reflected light flux (32) on the opposite side of the area to be illuminated (12).

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 stage in the production of a luminous flux; - a step of concentrating the light flux into a beam of specularly deflected light (31) integrated within a diffusely reflected light flux (32); characterized in that a target to be illuminated (11) is positioned outside the diffusely reflected light flux (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.

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