LASER STIMULATED WHITE-LIGHT LIGHTING SYSTEM

Abstract

The present invention discloses a laser stimulated white light lighting system, it includes a hemispherical reflector, a light-permeable board, a wavelength conversion layer, a reflective layer and plural heat-radiating structures, wherein the laser light emitted by a laser light source passes through a first light entrance hole of the hemispherical reflector and subsequently through the wavelength conversion layer to produce white light. With the implementation of the present invention, complex production process or equipment is not required thus reduce the system cost, the lighting system is capable of accurately outputting white light and promoting photon recycling effect to raise illumination efficiency. With the addition of a second light entrance hole, wavelength-division or angular division multiplexing can be carried out to raise the intensity of the output white light without increasing the etendue of the source light, thereby widening the range of application of the lighting system.

Claims

1. A laser stimulated white-light lighting system, comprising: a hemispherical reflector having a reflective curved surface and an opening, wherein the reflective curved surface is provided with a first light entrance hole; a light-permeable board fixedly provided at the opening and having an excitation area; a wavelength conversion layer fixedly attached to the excitation area; a reflective layer formed on a surface of an inner side of the light-permeable board in a region outside the excitation area; and a plurality of heat-radiating structures fixedly provided on a surface of an outer side of the light-permeable board in a region outside the excitation area; wherein laser light emitted by a laser light source passes through the first light entrance hole and then through the wavelength conversion layer to produce white light.

2. The white-light lighting system of claim 1, wherein the light-permeable board and the hemispherical reflector are connected together to form a hemispherical reflective enclosure.

3. The white-light lighting system of claim 1, wherein the light-permeable board is formed of glass, a sapphire substrate, transparent ceramic, monocrystalline aluminum, or polycrystalline aluminum.

4. The white-light lighting system of claim 1, wherein the laser light is blue, and the wavelength conversion layer is a phosphor powder layer, a quantum dot layer, or a layer formed of a photoluminescent material.

5. The white-light lighting system of claim 1, wherein the wavelength conversion layer is a phosphor powder layer formed of yellow phosphor powder, of a mixture of red and green phosphor powder, or of a mixture of orange and green phosphor powder.

6. The white-light lighting system of claim 5, wherein the phosphor powder layer is formed as a phosphor powder film or a phosphor powder crystal.

7. The white-light lighting system of claim 5, wherein the phosphor powder layer is formed of yttrium aluminum garnet (YAG), a silicate, or a nitride.

8. The white-light lighting system of claim 1, wherein the wavelength conversion layer is spray-coated on the excitation area.

9. The white-light lighting system of claim 1, wherein the laser light has a wavelength ranging from 360 to 480 nm.

10. The white-light lighting system of claim 1, wherein at least one of the heat-radiating structures is a heat-radiating fin.

11. The white-light lighting system of claim 1, wherein the hemispherical reflector is further formed with at least one second light entrance hole.

12. The white-light lighting system of claim 11, wherein each said second light entrance hole allows passage of blue light from a blue laser to the wavelength conversion layer in order to produce white light.

13. The white-light lighting system of claim 11, wherein wavelength-division multiplexing at 430 nm and 460 nm or angular division multiplexing is carried out to raise intensity of the white light produced, without increasing etendue of the laser light or the blue light.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0015] The invention as well as a preferred mode of use, further objectives and advantages thereof will be best understood by reference to the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings, wherein:

[0016] FIG. 1 is a schematic sectional view of the laser stimulated white-light lighting system in an embodiment of the present invention;

[0017] FIG. 2 is a schematic front view of the light-permeable board in the lighting system in FIG. 1;

[0018] FIG. 3 is a schematic perspective view of the laser stimulated white-light lighting system in FIG. 1;

[0019] FIG. 4 schematically shows how light is reflected between the hemispherical reflector and the light-permeable board in the lighting system in FIG. 1;

[0020] FIG. 5 is a schematic sectional view of the laser stimulated white-light lighting system in another embodiment of the present invention, wherein the lighting system is additionally provided with second light entrance holes; and

[0021] FIG. 6 is a schematic rear view of the hemispherical reflector in the lighting system in FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

[0022] Referring to FIG. 1 and FIG. 3, the laser stimulated white-light lighting system 100 in an embodiment of the present invention includes a hemispherical reflector 10, a light-permeable board 20, a wavelength conversion layer 30, a reflective layer 40, and a plurality of heat-radiating structures 50.

[0023] As shown in FIG. 1 and FIG. 3, the hemispherical reflector 10 of the laser stimulated white-light lighting system 100 has a reflective curved surface 13 and an opening 12. The reflective curved surface 13 is provided with a first light entrance hole 11.

[0024] There are no special limitations on the material of the hemispherical reflector 10. For example, the hemispherical reflector 10 can be formed of ceramic, metal, or other heat-resistant substances. The hemispherical reflector 10 is so shaped that light reflected from the reflective layer 40, which is provided on the light-permeable board 20, can be reflected by the hemispherical reflector 10 to an excitation area 21, as described in more detail below.

[0025] As shown in FIG. 1, FIG. 2, and FIG. 3, the light-permeable board 20 is fixedly provided at the opening 12 and has the excitation area 21. The laser stimulated white-light lighting system 100 is configured to emit white light WL by projecting laser light BR1 from a light source through the first light entrance hole 11 into the hemispherical reflector 10 and by reflecting the laser light BR1 in such a way that the reflected light strikes the excitation area 21 and passes through the wavelength conversion layer 30 to produce the white light WL.

[0026] Referring to FIG. 1 and FIG. 3, the light-permeable board 20 is connected with the hemispherical reflector 10 to form a hemispherical reflective enclosure. The laser light BR1 entering the first light entrance hole 11 is reflected by the reflective layer 40 to the reflective curved surface 13 of the hemispherical reflector 10 and then reflected by the reflective curved surface 13 to the excitation area 21.

[0027] The light-permeable board 20 can be formed of glass, a sapphire substrate, transparent ceramic, monocrystalline aluminum, or polycrystalline aluminum.

[0028] With continued reference to FIG. 1 and FIG. 3, the wavelength conversion layer 30 is fixedly attached to the excitation area 21 of the light-permeable board 20. For instance, the wavelength conversion layer 30 is applied to the excitation area 21 of the light-permeable board 20 by spray coating.

[0029] The wavelength conversion layer 30 in FIG. 1 and FIG. 3 is intended to be illuminated by the laser light BR1 having entered the first light entrance hole 11 and generate the white light WL by a color mixing process. The white light WL will be projected out of the laser stimulated white-light lighting system 100 from the excitation area 21.

[0030] The laser light BR1 can be blue, with a wavelength ranging from 360 to 480 nm. The wavelength conversion layer 30 can be a layer of phosphor powder, of quantum dots layer, or of a photoluminescent material.

[0031] When the wavelength conversion layer 30 is a phosphor powder layer that can be formed of yellow phosphor powder, a mixture of red and green phosphor powder, or a mixture of orange and green phosphor powder, and also the phosphor powder layer can be formed as a phosphor powder film or a phosphor powder crystal. Further, the forming material of the phosphor powder layer can be yttrium aluminum garnet (YAG), silicate, or nitride.

[0032] Referring again to FIG. 1 and FIG. 3, the reflective layer 40 is formed or coated on the inner surface of the light-permeable board 20 (i.e., the surface opposite the reflective curved surface 13) in a region excluding the excitation area 21.

[0033] As shown in FIG. 1, FIG. 3, and FIG. 4, the laser light BR1 incident on the aforesaid region excluding the excitation area 21 is reflected by the reflective layer 40 to the reflective curved surface 13 as reflected light RR. The reflective curved surface 13, in turn, reflects the reflected light RR to the excitation area 21 and the wavelength conversion layer 30 in order to produce the white light WL by a color mixing process.

[0034] To enhance heat dissipation from the laser stimulated white-light lighting system 100, referring to FIG. 1 and FIG. 3, the plural heat-radiating structures 50 are fixedly provided on the surface of the outer side of the light-permeable board 20 in a region excluding the excitation area 21.

[0035] At least one of the heat-radiating structures 50 can be an easily available heat-radiating fin which is effective in heat dissipation and has a relatively low cost of use.

[0036] The hemispherical reflector 10 may be further formed with at least one second light entrance hole 60 as shown in FIG. 5 and FIG. 6.

[0037] Each of the at least one second light entrance hole 60 allows passage of light from a blue laser 90. More specifically, the blue light BR2 emitted by the blue lasers 90 propagates through the second light entrance holes 60 respectively, is incident on the wavelength conversion layer 30, and produces the white light WL by a color mixing process taking place in the wavelength conversion layer 30.

[0038] When the laser light BR1 and the blue light BR2 passing respectively through the first light entrance hole 11 and the second light entrance holes 60 reach the wavelength conversion layer 30 at the same time, wavelength-division multiplexing or angular division multiplexing is carried out. As a result, the output, or intensity, of the white light WL (which is produced by a color mixing process taking place in the wavelength conversion layer 30) is raised without increasing the etendue of the laser light BR1 or the blue light BR2. This allows the range of application of the laser stimulated white-light lighting system 100 to be expanded. Etendue is also referred to as the optical invariant and can be used to describe the geometric properties (e.g., the divergence angle or a cross-sectional area) of a light beam.

[0039] In a nutshell, the laser stimulated white-light lighting system 100 can output the white light WL accurately by illuminating the wavelength conversion layer 30 (which is coated on the light-permeable board 20, where the heat-radiating structures 50 are located) with only the laser light BR1 or both the laser light BR1 and the blue light BR2 while the hemispherical reflector 10 enhances the photon recycling effect of the laser light BR1 or the blue light BR2 to increase light output efficiency. Moreover, the additional second light entrance holes 60 enable wavelength-division or angular division multiplexing so that the intensity of the output white light WL can be raised without increasing the etendue of the laser light BR1 or the blue light BR2.

[0040] The embodiments described above are intended only to demonstrate the technical concept and features of the present invention so as to enable a person skilled in the art to understand and implement the contents disclosed herein. It is understood that the disclosed embodiments are not to limit the scope of the present invention. Therefore, all equivalent changes or modifications based on the concept of the present invention should be encompassed by the appended claims.