Light bulb

Abstract

The present invention relates to a light bulb comprising a support structure formed at least 50% from a porous metal substrate functioning as a heat sink. The invention also relates to a light diffusing lens suitable for a light bulb comprising said metal substrate as well as a support structure comprising said metal substrate for a light bulb.

Description

Technical field

[0001] The present invention relates to a light bulb, a support structure for a light bulb and a light diffusing lens. State of the art

[0002] Most traditional light bulbs, such as incandescent bulbs and more modern ones, such as light-emitting diodes (LEDs), produce a significant amount of heat energy when in use. This dissipated heat can reduce the bulb's luminous efficacy, negatively affect the quality of the light emitted, and even shorten the bulb's lifespan.

[0003] In order to avoid reducing the problems related to the heat dissipated by a light bulb, it is for example known to insert heat dissipation elements in direct proximity to the light source, and therefore heat, in the bulb. These heat dissipation elements can be passive, e.g. heat sink by thermal convection or active, e.g. micro fans integrated directly into the bulb.

[0004] Because light bulb dimensions are widely standardized to allow for compatibility with existing fixtures or objects, the size of heat dissipation elements that can be integrated is limited. In particular, the diameter of a light bulb's screw base is typically calibrated to match standard standards. Thus, the volume available in a light bulb's base is predetermined by its intended use. To a lesser extent, the volume of the rest of the bulb is also determined by the bulb's intended use.

[0005] It is therefore necessary for the heat dissipation elements to be relatively compact so that they can be integrated into the bulb, while maintaining their heat dissipation capacity as high as possible.

[0006] CN107883362A describes a heat sink for an LED device consisting of a heat sink and an aluminum substrate attached by a thermally conductive adhesive to a metal disc disposed around the LED. The aluminum substrate is further soldered to a lower portion of the LED. This heat sink must then be integrated into a structural part supporting the LED, a bulb or lens and a bulb base.

[0007] Document KR20160134028A also describes a heat sink for an LED lighting device comprising a thermally conductive polymer element for transferring heat to an aluminum foam element cooling by natural convection. This heat sink must also be mounted on a structural part supporting all the other elements of the bulb.

[0008] Furthermore, light bulbs, and particularly LED bulbs, are not usually designed to allow interchangeability of components, whether for the purpose of recycling the different elements separately or for simplified repair purposes. Indeed, these bulbs are generally designed as single-use without the possibility of replacing parts or as complex parts whose repair or replacement of components requires the intervention of a professional. There is therefore also a need for bulbs whose different components are assembled in an easily reversible manner in order to allow their recycling and / or to extend their lifespan by replacing certain parts as needed. Brief summary of the invention

[0009] An object of the present invention is the provision of a light bulb mitigating the limitations known in the prior art.

[0010] Another object of the present invention is the provision of a light bulb making it possible to reconcile the compactness requirements of a bulb with the efficiency of a heat sink.

[0011] These goals are achieved in particular by means of a light bulb comprising: a support structure extending along a longitudinal axis between a first end and a second end, a base supported by the first end, a light source supported by the second end, a diffusion lens supported by the second end and comprising an interior volume delimited by a transparent lateral portion so as to transmit at least partially light emitted by the light source and an upper portion, the light source being arranged in the interior volume of the diffusion lens, characterized in that the support structure comprises a porous metal substrate for dissipating heat, the porous metal substrate constituting at least 50% of a total volume of the support structure.

[0012] According to one embodiment, the porous metal substrate constitutes at least 80% of the support structure, preferably at least 90% of the support structure.

[0013] According to one embodiment, a diameter of the second end is equal to a diameter of the diffusion lens.

[0014] According to one embodiment, a diameter of the first end is less than a diameter of the second end.

[0015] According to one embodiment, a height of the support structure measured along the longitudinal axis is greater than or equal to 50% of a total height of the bulb measured along the longitudinal axis.

[0016] According to one embodiment, the porous metal substrate is a metal foam, preferably an aluminum foam.

[0017] In one embodiment, the support structure includes a base attachment disposed on a surface of the first end and operable to removably attach the base to the support structure, the base attachment being embedded in a first embedding cavity of the support structure.

[0018] In one embodiment, the support structure includes a diffusion lens attachment disposed on a surface of the second end and operable to removably attach the diffusion lens to the support structure, the diffusion lens attachment being embedded in a second embedding cavity of the support structure.

[0019] According to one embodiment, the upper portion of the diffusion lens comprises: a plurality of rear ridges extending radially from the center of the upper portion and allowing light emitted by the light source to be reflected towards a rear area of ​​the diffusion lens opposite a front area, the diffusion lens being located between the support structure and the front area relative to the longitudinal axis.

[0020] According to one embodiment, the upper portion of the diffusion lens further comprises: a plurality of front ridges extending radially from a center of the upper portion and for transmitting light emitted by the light source to a front area of ​​the lens.

[0021] According to one embodiment, each front ridge of the plurality of front ridges is planar.

[0022] According to one embodiment, each rear groove of the plurality of rear grooves forms a protruding edge opposite the interior volume of the lens so that the light emitted by the light source is reflected by total reflection effect.

[0023] According to one embodiment, each rear streak further comprises a portion provided with a reflective coating.

[0024] According to one embodiment, the front ridges are arranged alternately with the rear ridges.

[0025] According to one embodiment, the upper portion is curved toward the center of the upper portion such that a thickness of the upper portion increases from the center toward a periphery of the upper portion.

[0026] These objects are also achieved by means of a support structure adapted for use in a light bulb as previously described.

[0027] These objects are also achieved by means of a light diffusing lens adapted for use in a light bulb as previously described. Brief description of the figures

[0028] Examples of implementation of the invention are indicated in the description illustrated by the appended figures in which: There Figure 1a illustrates a side view of a porous metal substrate support structure for a light bulb. Figure 1billustrates a perspective view of the support structure of the Figure 1a . There Figure 2a illustrates a side view of a porous metal substrate support structure for a light bulb including base and diffusion lens attachments. Figure 2b illustrates an exploded view of the support structure of the Figure 2a . There Figure 3a illustrates a cross-sectional view of a light bulb comprising a porous metal substrate support structure, a base, and a diffusion lens. Figure 3b illustrates a perspective view of the light bulb of the Figure 3a . There Figure 4 illustrates an exploded view of a light bulb according to the invention. The Figure 5a illustrates a perspective view of a light diffusing lens according to the invention showing an outer portion of the lens. The Figure 5billustrates a perspective view of a light diffusing lens according to the invention showing an interior portion of the lens. The Figure 5c illustrates a top view of a light diffusing lens according to the invention. The Figure 5d illustrates a sectional view of a light diffusing lens according to the invention. Example(s) of embodiment of the invention Support structure

[0029] The present invention relates to a light bulb 1 comprising a support structure 2 supporting a base 3, a light source 4 and a light diffusing lens 5.

[0030] The support structure 2 comprises a porous metal substrate 23 representing at least 50% of the total volume of the support structure and serving as a heat sink.

[0031] The term porous metal substrate refers to any class of metallic materials that include pores and whose thermal conductivity properties allow its use as a heat sink. Metal foams, whether closed-cell or open-cell, are a preferred class of materials for the production of porous metal substrates.

[0032] The support structure 2 thus advantageously combines a first function which is to serve as a structural part to which other components (base, light source, diffusion lens, etc.) are fixed and a second function which is to serve as a heat sink.

[0033] As a structural part, the support structure 2 has mechanical properties (dimensions, rigidity, etc.) suitable for serving as a support base for the other elements. As illustrated in the Figure 1, the support structure 2 extends along a longitudinal axis L between a first end 21 intended to support the base 3 and a second end 22 intended to support the light source 4 and the light diffusion lens 5. Thus, the diameter d of the first end 21 must be sufficient to accommodate the base 3 of the bulb. Similarly, the diameter D of the second end must be sufficient to accommodate the light source 4 and the diffusion lens 5. Furthermore, the rigidity of the structure and in particular of the metal substrate must be sufficient to ensure that the other elements are held in place by the support structure and to prevent damaging structural deformations of the bulb during its use.

[0034] The porosity of the metal substrate is adapted on the one hand to guarantee the structural integrity of the support structure by providing sufficient rigidity, and on the other hand to maximize heat dissipation. Thus, the porosity of the metal substrate is advantageously between 40% and 80%, preferably between 60% and 70%. According to one embodiment, the porosity of the metal substrate is 66%.

[0035] The heat dissipation properties of the porous metal substrate 23 are mainly determined by the heat exchange surface as well as by the limitation of pressure losses.

[0036] According to one embodiment, the porous metal substrate 23 represents a significant proportion of the total volume of the support structure 2. This proportion is advantageously at least 80%, or even at least 90% of the total volume of the support structure 2. Indeed, the more the metal substrate is proportionally present in the support structure, the more advantageous the heat dissipation properties are.

[0037] With the exception of some fixing elements (eg the base 3, the light source and / or the diffusion lens 5) or electronic components, the entire support structure 2 can be composed of the porous metal substrate 23. It is thus possible to obtain a support structure that is as compact as possible while maximizing the effect of the heat sink since almost the entire support structure 2 is then composed of the porous metal substrate 23.

[0038] According to one embodiment, the diameter of the second end 22 of the support structure 2 is equal to the diameter of the diffusion lens 5. As illustrated in the Figure 3a , the diameter of the second end 22 of the support structure 2 can coincide with the diameter of the porous metal substrate 23 which is thus also equal to the diameter of the diffusion lens 5. This configuration makes it possible in particular to do without additional transition elements between the support structure 2 and the diffusion lens 5 which would add to the size of the bulb while not serving to dissipate heat.

[0039] In order to reinforce the structural integrity of the bulb and to be able to have diffusion lenses of larger diameter than the diameter of the base, the diameter D of the second end 22 is advantageously larger than the diameter d of the first end 21. This characteristic, illustrated in the Figure 1a, also allows the bulb to have an overall geometry close to traditional bulbs with a flared shape and thus be compatible with many existing lighting devices.

[0040] According to an embodiment illustrated in the Figure 3a , the support structure 2 has a height h, measured along the longitudinal axis L, greater than or equal to 50% of the total height of the bulb, that is to say of the assembly consisting of the support structure 2, the base 3 and the diffusion lens 5. In this way, an even larger portion of the body of the bulb also has a heat dissipation function, a fortiori when the proportion of porous metal substrate 23 included in the support structure 2 is very large.

[0041] As mentioned above, the porous metal substrate 23 may be a metal foam. According to a preferred embodiment, it is an aluminum or copper foam.

[0042] According to one embodiment, the support structure 2 includes a base attachment 24 disposed on a surface of the first end 21 of the support structure and making it possible to attach the base 3 to the support structure. Advantageously, this base attachment allows reversible attachment of the base 3 to the support structure 14 so as to allow easy replacement of the base if it is damaged or non-functional.

[0043] The base attachment 24 is advantageously embedded in a first embedding cavity of the support structure 2. The base attachment 24 can for example be embedded directly in an embedding cavity of the porous metal substrate 23.

[0044] According to an embodiment illustrated in the Figure 3a , the base attachment 24 comprises a cylinder of which an external surface is threaded and corresponds to a thread of an internal surface of the base 3 so as to allow the screwing of the base 3 onto the base attachment 24.

[0045] The support structure 2 may also include a diffusion lens attachment 25 disposed on a surface of the second end 22 of the support structure 2 and for attaching the diffusion lens 5 to the support structure 2. This diffusion lens attachment 25 typically allows reversible attachment of the diffusion lens so that it can be easily exchanged.

[0046] According to an embodiment illustrated in the Figure 3a, the diffusion lens attachment 25 comprises a cylinder, a portion of the outer surface of which is threaded and corresponds to a thread on an inner surface of the diffusion lens so as to allow the diffusion lens 5 to be screwed onto the attachment 25. The thread of the diffusion lens may be a sectional thread 55 as illustrated in the Figure 5b for example to enable injection-moulding of the diffusion lens.

[0047] This reversibility of the fasteners advantageously makes it easier to recycle the various components of the bulb, these being fixed to each other in a removable manner, typically without glue. Similarly, the fixing by embedding the base and diffusion lens fasteners (24, 25) to the support structure 2, or even to the porous metal substrate 23 directly, also allows for easy disassembly and recycling of these various elements.

[0048] The support structure 2 may also comprise an internal channel so as to connect the first end 21 to the second end 22. This channel may make it possible to electrically or electronically connect the light source arranged on the second end 22 to a power source and / or an electronic module, e.g. a PCB, arranged in the base 3 of the bulb. Diffusion lens

[0049] The function of the light diffusion lens 5 is to diffuse the light emitted by the light source 4 outside the bulb 1. Depending on the use of the bulb, the diffusion requirements can vary significantly. Indeed, the diffusion lens can influence the directivity of the bulb, i.e. the angular range over which the emitted light is concentrated, but also the intensity or colorimetry of the emitted light.

[0050] Directivity is a delicate parameter to optimize, especially when the bulb is designed to recreate light as natural as possible. Indeed, it is difficult to recreate conditions of light evenly distributed over a given volume using a point light source that cannot emit at 360° due to the presence of elements (e.g. structural elements of the bulb) close to the source and interfering with the diffusion of light.

[0051] It is thus typically difficult to obtain natural illumination in the area behind the bulb since the base, or even other structural elements, are interposed between the light source and this rear area. This problem is even more significant when the light source only emits light over a restricted angular range. Typically, "chip on board" LEDs (abbreviated COB) or embedded chip LEDs can only emit directly over a range between 0° and 180° maximum because of the presence of the chip (and the support of this chip) which blocks diffusion towards the rear.

[0052] Diffusion lenses can be adapted to compensate for this lack of illumination towards the rear area of ​​the bulb.

[0053] Thus, according to another aspect, the present invention relates to a light diffusion lens 5 making it possible to directly illuminate at least a portion of a rear zone of the bulb on which it is arranged.

[0054] As illustrated for example on the Figure 4 , this light diffusion lens 5 comprises a transparent lateral portion 51 so as to at least partially transmit light emitted by a light source 4 towards a lateral zone outside the lens 5, as well as an upper portion 52. These two portions delimit an interior volume intended to accommodate the light source 4.

[0055] Advantageously, the upper portion 52 comprises a plurality of rear grooves 522 adapted to reflect the light emitted by the light source 4 towards a rear zone 54 of the diffusion lens 5. When the diffusion lens 5 is placed on a bulb, the rear zone corresponding to the rear zone of the bulb, that is to say the zone arranged on the side of the support structure 2 and the base 3 of the bulb as opposed to the front zone designating the zone located on the side of the diffusion lens 5 relative to a longitudinal axis L of the bulb 1.

[0056] The rear grooves form an optical surface for reflecting the light emitted by the light source 4.

[0057] According to an embodiment illustrated in the Figure 4, each rear groove has two symmetrical surfaces forming a projecting edge with an angle substantially equal to 90° in the azimuthal direction, i.e. in the direction perpendicular to the longitudinal axis L. Compared to a single flat surface, the incident light arrives on the main optical surface with a very high angle of incidence (i.e. greater than 45°) and is reflected in total internal reflection instead of being transmitted, which makes it possible to dispense with metallization to obtain a reflection. The use of two symmetrical surfaces makes it possible to redirect the light downwards, like a mirror. The first surface deflects the light by 90°, then the second surface deflects the light by a further 90°. This makes it possible to make a half-turn (180°) of the light, redirecting it largely, or even totally, towards the rear zone 54 of the lens.

[0058] In the elevation direction, the profile of each rear groove is optimized to obtain an intensity diagram ranging from 90° to 135° from the optical axis of the light source 4.

[0059] Preferably, the rear grooves are made of a material having a high optical refractive index so that the total internal reflection angle is reached more quickly. The family of transparent thermoplastics is for example suitable for the production of the rear grooves and more generally of the entire diffusing lens. Polycarbonate (PC) and polymethyl methacrylate (PMMA) are examples suitable for the production of the diffusing lens 5.

[0060] Alternatively or additionally, each rear groove may be provided at least partially with a reflective coating in order to increase the reflection of the light emitted against each groove. It is thus, for example, possible to obtain edges whose apex angle is less than or greater than 90°, while maintaining a sufficient light reflection coefficient to send it back to the rear area.

[0061] According to another embodiment illustrated in the Figure 5a, the upper portion 52 of the diffusion lens 5 comprising, in addition to the rear grooves 522, a plurality of front grooves 521 extending radially from a center of the upper portion 5221 and making it possible to transmit the light emitted by the light source 4 to a front zone 53 of the diffusion lens 5. These front grooves operate in light transmission and structure the beam of light emitted between 0° and 90° of the optical axis of the light source 4. Thus, the sum of the contributions of the rear grooves and the front grooves forms an isotropic beam ranging from 0° to 135° of the optical axis of the light source 4.

[0062] Advantageously, the rear streaks are arranged alternately with the front streaks so as to homogenize the beam in the azimuthal plane.

[0063] According to one embodiment, the front ridges are planar in the azimuthal direction in order to minimize the refraction of the emitted light and thus to maximize the proportion of light emitted by the light source which passes through the diffusion lens towards the front zone of the lens. The term "planar" here does not mean that each front ridge 521 is confined to a plane, but rather that each front ridge 521 can be obtained as a union of straight line segments, each of these segments extending in an azimuthal plane. Thus the height of the profile of these front ridges in a plane comprising the longitudinal axis L can vary.

[0064] As illustrated on the Figure 5c, the diffusion lens 5 can have several axes of symmetry, for example relative to a transverse axis 56 orthogonal to the longitudinal axis L. Thus, the diffusion lens can be cylindrical, conical, polygonal or of any other geometry adapted to the needs or the aesthetics required by its function.

[0065] In the context of the present invention, the directivity of the bulb is particularly important because, due to its composition including a porous metal substrate, the support structure 2 is generally opaque and thus blocks a significant portion of the light towards the rear area of ​​the bulb.

[0066] As illustrated on the Figures 5b And 5d , the diffusion lens may include a thread per section 55 allowing its attachment to a support structure and allowing its manufacture by injection.

[0067] The upper portion 52 of the diffusion lens 5 may be curved towards the center of the upper portion 5221 so that a thickness of the upper portion increases from the center towards a periphery of the upper portion. This central hollow makes it possible in particular to improve the intensity profile according to the elevation angle. In particular, this hollow makes it possible to limit certain homogeneity defects such as overintensity at 0° as well as drops in intensity over certain angular ranges, typically between 50° and 80°.

[0068] The diffusion lens 5 is advantageously combined with the support structure 2 as described above. Indeed, the support structure of the present invention is generally opaque due to the porous metal substrate 23 and prevents direct radiation from the light source 4 towards the rear area of ​​the bulb.

[0069] The present invention also relates to a support structure 2 suitable for use in a light bulb 1 as described above. Reference numbers used in the figures

[0070] Light bulb 1 Longitudinal axis L Support structure 2 Height of the support structure H First end 21 Diameter of the first end d Second end 22 Diameter of the second end D Porous metal substrate 23 Base fixing 24 Diffusion lens attachment 25 Cheek 3 Light source 4 Diffusion lens 5 Side portion 51 Upper portion 52 Front streak 521 Rear streak 522 Center of the upper portion 5221 Front zone 53 Back area 54 Thread by section 55 Transverse axis 56

Claims

1. A light bulb (1) comprising: a support structure (2) extending along a longitudinal axis (L) between a first end (21) and a second end (22), a base (3) supported by the first end (21), a light source (4) supported by the second end (22), a diffusion lens (5) supported by the second end (22) and comprising an interior volume delimited by a transparent lateral portion (51) so as to at least partially transmit light emitted by the light source (4) and an upper portion (52), the light source (4) being arranged in the interior volume of the diffusion lens (5), characterized in that the support structure (2) comprises a porous metal substrate (23) for dissipating heat, the porous metal substrate (23) constituting at least 50% of a total volume of the support structure (2).

2. Light bulb (1) according to claim 1, the porous metal substrate (23) constituting at least 80% of the support structure (2), preferably at least 90% of the support structure (2).

3. Lighting bulb (1) according to one of claims 1 to 2, a diameter (D) of the second end (22) being equal to a diameter of the diffusion lens (5).

4. Light bulb (1) according to one of the preceding claims, a diameter (d) of the first end (21) being less than a diameter (D) of the second end (22).

5. Lighting bulb (1) according to one of the preceding claims, a height (h) of the support structure (2) measured along the longitudinal axis (L) being greater than or equal to 50% of a total height (H) of the bulb (1) measured along the longitudinal axis (L).

6. Light bulb (1) according to one of the preceding claims, the porous metal substrate (23) being a metal foam, preferably an aluminum foam.

7. A light bulb (1) according to any preceding claim, comprising a base attachment (24) disposed on a surface of the first end (21) and for removably attaching the base (3) to the support structure (2), the base attachment (24) being embedded in a first embedding cavity of the support structure (2).

8. A lighting bulb (1) according to any preceding claim, comprising a diffusion lens attachment (25), arranged on a surface of the second end (22) and for removably attaching the diffusion lens (5) to the support structure (2), the diffusion lens attachment (25) being embedded in a second embedding cavity of the support structure (2).

9. Lighting bulb (1) according to one of the preceding claims, wherein the upper portion (52) of the diffusion lens (5) comprises: a plurality of rear ridges (522) extending radially from the center of the upper portion (5221) and making it possible to reflect the light emitted by the light source (4) towards a rear zone (54) of the diffusion lens (5) opposite a front zone (53), the diffusion lens being located between the support structure (2) and the front zone (53) relative to the longitudinal axis (L).

10. Lighting bulb (1) according to the preceding claim, the upper portion (52) of the diffusion lens (5) further comprising: a plurality of front grooves (521) extending radially from a center of the upper portion (5221) and allowing the transmission of light emitted by the light source (4) towards a front area of ​​the lens (54).

11. Light bulb (1) according to the preceding claim, each front groove (521) of the plurality of front grooves being planar.

12. Lighting bulb (1) according to one of claims 10 to 11, each rear groove (522) of the plurality of rear grooves forming a projecting edge opposite the interior volume of the diffusion lens (5) so that the light emitted by the light source (4) is reflected by total reflection effect.

13. Lighting bulb (1) according to one of claims 10 to 12, each rear groove (522) further comprising a portion provided with a reflective coating.

14. Light bulb (1) according to one of claims 10 to 13, the front ridges (521) being arranged alternately with the rear ridges (522).

15. A light bulb (1) according to one of claims 10 to 14, the upper portion (52) being curved towards the centre of the upper portion (5221) such that a thickness of the upper portion increases from the centre towards a periphery of the upper portion.

16. Support structure (2) adapted to be used in a light bulb (1) according to one of claims 1 to 15.

17. Light diffusing lens (5) suitable for use in a light bulb (1) according to one of claims 1 to 15.

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