CN110778926B

CN110778926B - Lighting device

Info

Publication number: CN110778926B
Application number: CN201910606360.9A
Authority: CN
Inventors: 徐梦梦; 张贤鹏; 李屹
Original assignee: YLX Inc
Current assignee: YLX Inc
Priority date: 2018-07-26
Filing date: 2019-07-05
Publication date: 2023-06-09
Anticipated expiration: 2039-07-05
Also published as: WO2020019753A1; CN110778926A

Abstract

The invention relates to a lighting device comprising: an excitation light source that emits excitation light of a first wavelength distribution; a light conversion device comprising: the light guide piece comprises a first end, a second end opposite to the first end, and a first surface and a second surface which are connected with the first end and the second end, wherein the first end is provided with a light incident surface of the light conversion device, and the first surface forms a light emergent surface of the light conversion device; the reflective diffusion piece is arranged at the second end of the light guide piece and is used for diffusing and reflecting the excitation light back into the light guide piece; and a wavelength conversion member disposed adjacent to the second face of the light guide for converting the excitation light into a excited light of a second wavelength distribution and reflecting the excited light back into the light guide to exit from the first face of the light guide. The invention improves the uniformity of the light output of the lighting device and avoids the problems of heat concentration and conversion efficiency reduction caused by directly exciting the wavelength conversion member by the excitation light source with overhigh power density.

Description

Lighting device

Technical Field

The present disclosure relates to lighting devices, and particularly to a lighting device.

Background

The LED light source is a fourth-generation light source behind an incandescent lamp, a fluorescent lamp and a high-intensity gas lamp, has the advantages of energy conservation, environmental protection, long service life, small volume, light weight, firm structure, low working voltage and the like, and the problems of lower brightness, rapid efficiency and the like of the traditional LED light source are solved. As an alternative, a light source (hereinafter referred to as a "laser fluorescent light source") that emits light by exciting a fluorescent material with laser light has been attracting more and more attention because of advantages such as high electro-optical conversion efficiency, high luminance, inefficiency dip, and small volume.

The existing common laser fluorescent light source adopts blue laser as an excitation light source and excites a wavelength conversion element to obtain emergent light with specific wavelength, but the laser fluorescent light source has the problems of lower luminous efficiency, local overheating and the like of a wavelength conversion material due to small laser spot area and overhigh excitation light power density.

Further, the use of the light guide element to homogenize the excitation light can also avoid the problem of heat concentration and reduction in conversion efficiency in the wavelength conversion element due to an excessive excitation light power, for example, patent literature: while it is disclosed in CN 105074945A, EP2947484, WO2014198619, etc. that uniform light is achieved by using a light guiding element in a laser fluorescent light source, in the above patent documents, a transparent fluorescent light guiding element is usually made of single crystal or transparent ceramic of YAG: ce, and the light guiding element converts excitation light into light with another wavelength distribution while uniform light and guiding light, that is, functions of light guiding and wavelength conversion are simultaneously performed, any position of the light guiding element may be a light emitting center, so that uniformity of light is difficult to control.

There are also some prior arts in which a light guide is provided separately from wavelength conversion, a point light source is converted into a surface light source by a light guide, and then a phosphor is irradiated, so that the power density of excitation light irradiated onto the phosphor is reduced. However, in the prior art, the arrangement of the light guide and the peripheral parts of the light guide such as the reflecting member is not optimal, and the effect in terms of light uniformity is not ideal.

Disclosure of Invention

In view of the above, the present invention provides a lighting device to solve the above problems.

A lighting device, comprising:

an excitation light source that emits excitation light of a first wavelength distribution; and

A light conversion device comprising: the light guide piece comprises a first end, a second end opposite to the first end, and a first surface and a second surface which are connected between the first end and the second end, wherein the first end is provided with a light incident surface of the light conversion device, and the first surface forms a light emergent surface of the light conversion device; a reflective diffuser disposed at a second end of the light guide for diffusing and reflecting the excitation light back to the light guide; and a wavelength conversion member disposed adjacent to the second face of the light guide member for converting the excitation light into a lasing light of a second wavelength distribution, and reflecting the lasing light back to the light guide member and out of the first face of the light guide member.

The lighting device provided by the embodiment of the invention has the advantages that: by arranging the light guide member and the wavelength conversion member separately and arranging the reflective diffusion member on the opposite end face of the light incident surface of the light conversion device, the excitation light entering the light guide member of the light conversion device is not directly incident to the wavelength conversion member, but is changed in light distribution at the reflective diffusion member after being conducted by the light guide member, and then is incident to the wavelength conversion member arranged at the second surface position between the first end and the second end of the light guide member in a more uniform light distribution. On one hand, the wavelength conversion piece becomes a surface light source (which is different from a body light source of a transparent fluorescent light guide in the background art), which is beneficial to regulating and controlling the light emitting uniformity of the lighting device; on the other hand, through the light guide and the reflective diffusion piece arranged at the tail end of the light guide, the excitation light with small light spot area and high power density is converted into the excitation light with larger light spot area and lower power density, so that the problems of heat concentration and reduced conversion efficiency caused when the excitation light source with overhigh power density directly excites the wavelength conversion piece are effectively avoided, and meanwhile, the reflective diffusion piece arranged at the tail end of the light guide is further improved in light uniformity. In addition, compared with the background technology of a 'body light source', the wavelength conversion piece can receive uniform excitation light irradiation with a large area on the whole surface, and the excitation light power at each place is not different due to the difference of the distance from the excitation light source, so that the wavelength conversion piece can emit light and heat more uniformly.

Drawings

Fig. 1 is a schematic structural view of a lighting device according to a first embodiment of the present invention.

Fig. 2 is a schematic view of another angle of the light conversion device of the lighting device shown in fig. 1.

Fig. 3 is a schematic structural view of a lighting device according to a second embodiment of the present invention.

Fig. 4 is a schematic structural view of a lighting device according to a third embodiment of the present invention.

Fig. 5A and 5B are diagrams for comparing the principle of light guiding by the light guide in the first and third embodiments of the lighting device according to the present invention, wherein fig. 5A is a schematic diagram of light guiding by the light guide in the first embodiment, and fig. 5B is a schematic diagram of light guiding by the light guide in the second embodiment.

Fig. 6 is a schematic structural view of a lighting device according to a fourth embodiment of the present invention.

Fig. 7 is a schematic structural view of a lighting device according to a fifth embodiment of the present invention.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The term "or/and" as used herein includes any and all combinations of one or more of the associated listed items.

Referring to fig. 1 and 2, fig. 1 and 2 are schematic structural diagrams of a lighting device according to a first embodiment of the invention. The lighting device 1 comprises an excitation light source 11, a light guiding means 12 and a light converting means 13. The excitation light source 11 emits excitation light with a first wavelength distribution and a smaller spot area, in this embodiment, the excitation light source 11 is a point light source that emits excitation light with the first wavelength distribution, and the light guiding device 12 is configured to make the excitation light emitted by the excitation light source 11 incident at a specific position of the light conversion device 13 at a suitable angle; the light conversion device 13 is configured to convert the excitation light with a first wavelength distribution and a smaller spot area (such as a point light source) emitted by the excitation light source 11 into the outgoing light with a second wavelength distribution and a larger spot area (surface light source), and at least comprises a light guide 14, a wavelength conversion member 15, and a reflective diffusion member 16, wherein the light guide 14 and the wavelength conversion member 15 are separately arranged, the reflective diffusion member 16 is arranged at the end of the light guide 14, and the reflective diffusion member 16 cooperates with the light guide 14 to expand the spot area of the excitation light and further improve the uniformity of the light, for example, the point light source is converted into the surface light source, and then the wavelength conversion member 15 is excited to obtain the outgoing light with the second wavelength distribution. In the present embodiment, the separate arrangement means that the light guide 14 and the wavelength conversion member 15 are two mutually separable elements, which do not form part of each other.

In this embodiment, the lighting device 1 is a laser lighting device, and the excitation light source 11 may be a single or multiple laser light sources, preferably a blue laser light source. The light guiding device 12 is a collimating lens 12a disposed between the excitation light source 11 and the light conversion device 13, however, in other embodiments, the light guiding device 12 may be a combination of the collimating lens 12a and other optical elements, and only needs to make the excitation light emitted from the excitation light source 11 incident on a specific position of the light conversion device 13 at a suitable angle. In other embodiments, the light guiding means 12 may also be an optical device such as an optical fiber, a light rod, or the like.

The wavelength conversion member 15 may be a luminescent ceramic or a structure made of phosphor dispersed in silica gel or glass; the light guide 14 is superimposed on the wavelength conversion member 15, the light guide 14 preferably being sapphire, the light guide 14 at the same time improving the heat dissipation of the wavelength conversion member 15 due to the high thermal conductivity of sapphire. The light guide 14 includes a first end 141 adjacent to the light guiding device 12, a second end 142 opposite to the first end 141, the light guide 14 further includes a first surface 143 connecting the first end 141 and the second end 142 and far from the wavelength conversion member 15, a second surface 144 connecting the first end 141 and the second end 142 and near the wavelength conversion member 15, and a peripheral surface (not labeled) connecting the first end 141, the second end 142, the first surface 143 and the second surface 144, wherein the first surface 143 and the second surface 144 are polished to have a surface roughness of less than 400nm, more preferably less than 100nm, and the first surface 143 forms the light emitting surface of the light conversion device 13. The first end 141 of the light guide 14 is provided with a light incident surface of the light conversion device 13. In the present embodiment, the end face of the first end 141 of the light guide 14 is the light incident surface of the light conversion device 13, and the light guide 12 makes the excitation light emitted from the excitation light source 11 incident on the light incident surface of the light conversion device 13 at a light divergence half angle smaller than 1/2 times the inverse aspect ratio of the light guide 14. The aspect ratio of the light guide 14 is obtained by calculating the ratio of the length of the light guide 14 along the incident light direction to the diameter of the end face of the second end 142 of the light guide 14, and specifically in this embodiment, the distance from the first end 141 to the second end 142 of the light guide 14 is the length of the light guide 14, and the diameter of the maximum inscribed circle of the end face of the second end 142 of the light guide 14 can be regarded as the diameter of the end face of the second end 142. The light emission angle refers to an angle corresponding to a cone of light having a luminous intensity of not less than 50% of the luminous intensity of the center of the light beam.

The light conversion device 13 includes a light splitting member 17, a reflecting member 18, and a heat dissipating member 19 in addition to the light guide member 14 and the wavelength conversion member 15. The light guide 14 is stacked on the wavelength conversion member 15, and the reflecting member 18 includes a plurality of reflecting elements, and in this embodiment, the reflecting member 18 includes a reflecting element 18a disposed on a peripheral side of the light guide 14 and the wavelength conversion member 15, and a reflecting element 18b disposed on a side of the wavelength conversion member 15 away from the light guide 14. Since the light guide 14 and the wavelength conversion member 15 are each substantially rectangular parallelepiped, and the peripheral surfaces thereof include two surfaces, in this embodiment, the reflective element 18a further includes

reflective elements

181a and 183a, and the

reflective elements

181a and 183a are disposed on the peripheral surfaces of the light guide 14 and the wavelength conversion member 15 to prevent the excitation light and the laser light from exiting from the peripheral surfaces of the light guide 14 and the wavelength conversion member 15. The light-splitting member 17 is disposed at the first end 141 of the light guide 14 and extends to cover the end surface of the wavelength conversion member 15 on the side, and the light-splitting member 17 faces the light guide 12, specifically, in this embodiment, the light-splitting member 17 is disposed adjacent to the light incident surface of the light conversion device 13. In the present embodiment, "adjacent" includes "abutting" as in the case where the spectroscopic member 17 is disposed adjacent to the light conversion device 13, including the case where the spectroscopic member 17 abuts against the light incident surface of the light conversion device 13. The reflective diffusion member 16 is disposed at the second end 142 of the light guide member 14 and extends to cover the end face of the wavelength conversion member 15 on the side thereof, for diffusing and reflecting the excitation light emitted from the second end 142 of the light guide member 14 back to the light guide member 14. The

reflective elements

181a, 183a and the reflective diffuser 16 preferably have a reflectivity of greater than 90% in the range of 400-800nm, and may be specular or diffuse reflective, with the reflective diffuser 16 preferably being diffuse reflective. The reflective element 18b preferably has a reflectivity greater than 90% in the range of 400-800nm, and may be a specular or diffuse reflective element, preferably highly reflective aluminum with a relatively high thermal conductivity. The light splitting element 17 is a dichroic sheet 17a, and transmits light of a first wavelength distribution in a specific angle range, and reflects light of the first wavelength spectrum and light of a second wavelength distribution in other angle ranges. In this embodiment, the dichroic sheet 17a transmits blue light incident at 0 to 5 degrees, reflects blue light incident at other angles, and light of other wavelengths. The heat dissipation element 19 is a heat sink, preferably, the heat conductivity of the heat sink is higher than 30W/m·k, and the heat dissipation element 19 is disposed on the other side of the reflective element 18b away from the wavelength conversion element 15, so as to facilitate heat dissipation of the wavelength conversion element 15.

In the present embodiment, the wavelength conversion material 15 and the light guide 14, the reflective element 18, the reflective diffusion material 16, the wavelength conversion material 15 and the light guide 14, and the dichroic sheet 17a are bonded to each other with a material having a low refractive index and a high light transmittance such as silica gel, so that the respective interfaces are in optical contact.

In this embodiment, the blue laser light emitted from the excitation light source 11 is collimated by the collimating lens 12a, then enters the light guide 14, and is incident on the reflective diffuser 16 approximately vertically, and after being diffusely reflected by the reflective diffuser 16, the blue laser light is counter-transmitted at a certain angle, as shown by the arrow in fig. 1, and the counter-transmitted blue laser light after being diffusely reflected can be divided into three parts I, II and III, wherein part I of the blue laser light is incident on the first surface 143 of the light guide 14, i.e., the interface between the light guide 14 and the air, part II of the blue laser light is incident on the second surface 144 of the light guide 14, i.e., the interface between the light guide 14 and the wavelength converter 15, and another part III of the blue laser light with a smaller proportion is counter-transmitted to the light incident surface of the light guide 14 in a direction parallel to the first surface 143 and the second surface 144 of the light guide 14.

After the blue laser light of the part I is incident on the first surface 143 of the light guide 14, a small part of the blue laser light does not meet the total reflection condition and exits from the first surface 143; a further majority of the blue laser light satisfies the total reflection condition, is reflected to the second face 144 of the light guide 14, i.e. the interface between the light guide 14 and the wavelength conversion member 15, and since the total reflection critical angle at the second face 144 is greater than the total reflection critical angle at the first face 143, a portion of the blue laser light having an incidence angle smaller than the critical angle at the second face 144 of the light guide 14 can enter the wavelength conversion member 15 and be converted into light of a second wavelength distribution, which is approximately lambertian distributed light, and finally exits from the first face 143 of the light guide 14 under the action of the

reflective elements

181a, 183a, the reflective diffuser 16, and the

dichroic sheets

17a, 18 b; a portion of the blue laser light at an angle of incidence greater than the critical angle of the second face 144 of the light guide 14 cannot enter the wavelength conversion member 15 and is eventually lost in the light guide 14.

After the part II of blue laser light is incident on the second surface 144 of the light guide 14, the blue laser light which does not meet the total reflection condition enters the wavelength conversion member 15 and is converted into light with a second wavelength distribution, and the light with the second wavelength distribution is approximately lambertian distributed light, and finally, the light is emitted from the first surface 143 of the light guide 14 under the action of the

reflective elements

181a and 183a, the reflective diffuser 16, the dichroic sheet 17a and the reflective element 18 b; while another part of the blue laser light satisfying the total reflection condition cannot be incident on the wavelength conversion member 15, can only propagate in the light guide member 14, and finally is lost.

Part III of the blue laser light is transmitted to the light incident surface of the light guide 14, and the part III of the blue laser light cannot be incident on the wavelength conversion member 15, and eventually is also lost.

It will be appreciated that to reduce losses of blue laser light, scattering structures may be provided at the interface between the light guide 14 and the wavelength conversion member 15, such as the addition of TiO between the light guide 14 and the wavelength conversion member 15 ₂ The scattering particles, or microstructures, may be machined into the second face 144 of the light guide 14, and the size of the scattering particles or microstructures is greater than or equal to the wavelength of the blue laser light, preferably the size of the microstructures is 1-10 times the wavelength of the blue laser light, so that the second face 144 of the light guide 14 has a certain roughness.

It is understood that in other embodiments, the surface of the heat sink 19 near the side of the wavelength conversion member 15 may be treated to have a reflectivity greater than 90% in the range of 400-800nm, and the reflective element 18b may be omitted.

It will be appreciated that in other embodiments, the side of the wavelength converting element 15 facing away from the light guide 14 may be provided as a reflective surface, so that the provision of the reflective element 18b is omitted.

It will be appreciated that although in the above embodiments the second face 144 is disposed opposite the first face 143, in other embodiments the second face 144 may be disposed adjacent the first face 143, even when the light guide 14 is a cylinder having more peripheral sides than four sides in other embodiments the second face 144 may be disposed neither opposite nor adjacent the first face 143.

In the above-described embodiment, the light guide 14 is a solid light guide. It will be appreciated that in other embodiments the light guide may be a hollow body, and that when the light guide is a hollow body the wavelength converting element may be disposed inwardly of the second face of the light guide and the reflective diffuser may be disposed inwardly of the second end of the light guide. The light guide member has more excellent effect in the embodiment of the invention because the light emitted from the reflective diffuser member can return the part I of the light to the inside of the light guide member by the total reflection effect of the interface between the solid light guide member and the air instead of directly emitting the light from the light guide member, thereby avoiding the insufficient utilization ratio of the excitation light.

Fig. 3 is a schematic structural diagram of a lighting device according to a second embodiment of the present invention. The illumination device 2 comprises an excitation light source 21, a light guiding means 22 and a light converting means 23. In this embodiment, the excitation light source 21 emits excitation light with a first wavelength distribution and a smaller spot area, the excitation light source 21 is a point light source that emits excitation light with the first wavelength distribution, the light guiding device 22 is configured to make the excitation light emitted by the excitation light source 11 incident at a specific position of the light conversion device 23 at a proper angle, the light conversion device 23 is configured to convert the excitation light with the first wavelength distribution and the smaller spot area (such as the point light source) emitted by the excitation light source 21 into outgoing light with the larger spot area (the area light source) with the second wavelength distribution, and the outgoing light with the larger spot area includes at least a light guide 24 and a wavelength conversion member 25 that are separately disposed, and a reflective diffusion member 26 that is disposed at the end of the light guide 24, where the reflective diffusion member 26 and the light guide 24 jointly expand the spot area of the excitation light and further promote uniformity of the light, for example, and then the outgoing light with the second wavelength distribution is obtained by the excitation wavelength conversion member 25. In this embodiment, the light conversion device 23 further includes a light splitting member 27, a reflecting member 28, and a heat dissipating member 29, wherein the reflecting member 28 includes a reflecting element 28a disposed on a peripheral side surface of the light guide 24 and the wavelength conversion member 25, and a reflecting element 28b disposed on a side of the wavelength conversion member 25 away from the light guide 24. Since the arrangement of the light guide 24, the wavelength conversion member 25, the reflection member 28, the reflection type diffusion member 26, and the heat dissipation member 29 is the same as or similar to that in the first embodiment, the description will not be repeated here.

In this embodiment, the difference from the first embodiment is mainly in the light guiding device and the spectroscopic member. In the present embodiment, the light guiding device 22 is a focusing lens 22a disposed between the excitation light source 21 and the light conversion device 23, however, in other embodiments, the light guiding device 22 may be a combination of the focusing lens 22a and other optical elements, and only the combination is required to make the excitation light emitted from the excitation light source 21 incident on a specific position of the light conversion device 23 at a suitable angle. The light-splitting member 27 is provided on the peripheral side surfaces of the light guide 24 and the wavelength conversion member 25 and is close to the light guide 22, and in this embodiment, the light-splitting member 27 is an optically extended amount light-splitting sheet, and the light-splitting member 27 transmits excitation light in a specific angle range to the light guide 24 and reflects excitation light in the laser and other angle ranges depending on the difference between the excitation light and the laser extension amount. As one embodiment, the light splitting member 27 is a reflecting element 271, and a through hole 272 is formed therein. The reflective element 271 may be a specular or diffuse reflective element, preferably the reflective element 271 has a reflectivity of greater than 90% in the range 400-800 nm.

In the present embodiment, the blue laser light emitted from the excitation light source 21 is focused by the focusing lens 22a, and is incident on the light guide 24 at a specific angle through the through hole 272 of the reflection element 271. Since the specific angle is an angle between the main optical axis of the incident light and the optical axis of the light incident surface of the light guide 24, and is not 0, the incident light is incident on the light guide 24 at an incident angle other than 0 degrees, and thus uniformity of the light emitted from the light guide 24 can be improved, and at the same time, the proportion of blue light incident on the wavelength conversion member 25 can be improved by providing the reflective element 271 at the light incident surface of the light guide 24, thereby improving the light emitting efficiency of the entire illumination device 2, as compared with the first embodiment. In addition, the relative positions of the excitation light source 21, the focusing lens 22a and the reflecting element 271 and the positions and the apertures of the through holes 272 on the reflecting element 271 can be set, so that the spot at the position of the through holes 272 of the reflecting element 271 is the smallest after the excitation light is focused by the focusing lens 22a, thereby ensuring that the blue laser emitted by the excitation light source 21 can efficiently pass through the through holes 272 and the aperture of the through holes 272 is the smallest, reducing the proportion of the light emitted from the light guide 24 through the through holes 272 and further improving the light emitting efficiency of the whole lighting device 2.

Fig. 4 is a schematic structural diagram of a lighting device according to a third embodiment of the present invention. The lighting device 3 includes an excitation light source 31, a light guiding device 32, and a light conversion device 33, where the excitation light source 31 emits excitation light with a first wavelength distribution and a small spot area, in this embodiment, the excitation light source 31 is a point light source emitting excitation light with the first wavelength distribution, the light guiding device 32 is configured to make the excitation light emitted by the excitation light source 31 incident on a specific position of the light conversion device 33 at a suitable angle, the light conversion device 33 is configured to convert the excitation light with the first wavelength distribution having the small spot area (such as a point light source) into outgoing light with the second wavelength distribution having the large spot area (a surface light source), and the light conversion device 33 includes at least a light guide 34, a wavelength conversion member 35, and a reflective diffusion member 36, where the light guide 34 is separately disposed on the wavelength conversion member 35, the reflective diffusion member 36 is disposed at an end of the light guide 34, and the reflective diffusion member 36 and the light guide 34 jointly expands the spot area of the excitation light and improves uniformity of the light, for example, and then converts the excitation light with the first wavelength distribution having the small spot area into outgoing light with the second wavelength distribution. In this embodiment, the light conversion device 33 further includes a light splitting member 37, a reflecting member 38, and a heat dissipating member 39, where the arrangement of the reflecting member 38, the light splitting member 37, and the heat dissipating member 39 may be the same as or similar to that in the first embodiment or the second embodiment, for example, a dichroic plate may be used for the light splitting member 37 as in the first embodiment, and a reflecting element provided with a through hole may be used for the light splitting member 37 as in the second embodiment.

The present embodiment differs from the first and second embodiments mainly in that the light guides 14 and 24 are substantially rectangular, and therefore, in the first and second embodiments, the light guide 14 is taken as an example, the light guide 14 has a substantially rectangular longitudinal section perpendicular to the first surface 143 and the second surface 144, the first surface 143 and the second surface 144 are substantially parallel, and the first surface 143 and the second surface 144 are substantially perpendicular to the peripheral surface of the light guide 14, and thus, the light intensity is easily emitted from the region of the first surface 143 close to the reflective diffuser 16 and the reflective element 18a to the region distant from the reflective diffuser 16 and the reflective element 18 a. However, in the third embodiment, the first surface 343 of the light guide 34 far from the wavelength conversion member 35 is not parallel to the second surface 344 near the wavelength conversion member 35, the first surface 343 is inclined, the second surface 344 is perpendicular to the peripheral side surface of the light guide 34, and at least one of the first surface 343 and the peripheral side surface of the light guide 34 is inclined, in this embodiment, the inclined state refers to a non-perpendicular and non-parallel state, specifically, the longitudinal section of the light guide 34 perpendicular to the first surface 343 and the second surface 344 is generally trapezoid, the first surface 343 is inclined to the end surface of the first end 341 and the end surface of the second end 342 of the light guide 34, and the distance between the first surface 343 and the second surface 344 gradually increases from the first end 341 to the second end 342 of the light guide 34, i.e. the distance between the first surface 343 and the second surface 344 is shorter near the first end 341 of the light guide 34 and longer near the second end 342 (i.e. near the reflective diffusion member 36). Therefore, the uniformity of the light emitted by the lighting device 3 can be improved, and the light emitted by the lighting device 3 is more uniform.

Referring to fig. 5A and 5B, the light guiding principle of the light guide with different shapes in the first embodiment and the third embodiment is described as follows: the

reflective diffuser

16, 36 completely changes the light distribution of the excitation light into lambertian light, so that the

reflective diffuser

16, 36 can be regarded as a lambertian surface light source, and the

first surfaces

143, 343 can be regarded as substantially a mirror surface by considering only one total reflection of the

first surfaces

143, 343. In fig. 5A corresponding to the first embodiment, the lambertian surface light source is actually a superposition of the reflective diffuser 16 and its virtual image 16' due to the total reflection of the first face 143 of the light guide 14; in fig. 5B corresponding to the third embodiment, the lambertian surface light source is actually a superposition of the reflective diffuser 36 and its virtual image 36', and 180 ° lambertian light emitted from the reflective diffuser 16 and its virtual image 16' or the reflective diffuser 36 and its virtual image 36' is incident on the

wavelength conversion member

15 or 35 disposed adjacent to the

second face

144, 344. It can be roughly seen that virtual image 36' in fig. 5B is closer to the portion of wavelength conversion member 35 near first end 341 than virtual image 16' in fig. 5A, and the central optical axis of virtual image 36' is closer to the portion of wavelength conversion member 35 near first end 341, so that more light is irradiated to the position of wavelength conversion member 35 away from reflective diffuser 36, thereby improving uniformity. The results obtained by the illuminance uniformity simulation experiment can also verify this.

It will be appreciated that in other embodiments, the shape of the light guide is not limited to trapezoid, but may be other shapes, and even, the first surface of the light guide may be curved, such as hyperboloid, paraboloid, ellipsoid, etc., or a combination of curved surface and plane, such as a plane in the middle, curved surfaces on both sides, etc., and only the requirement between the first surface and the second surface of the light guide is satisfied: the closer to the reflective diffuser, the greater the distance.

In the above embodiments, the cross sections of the light guide and the wavelength conversion member perpendicular to the longitudinal section are rectangular, however, it is understood that in other embodiments, the cross sections of the light guide and the wavelength conversion member may be circular, elliptical, trapezoidal, or other shapes other than rectangular. Accordingly, the shape of the first face of the light guide will also change accordingly, resulting in a corresponding change in the spot shape of the light emitted by the illumination device.

Referring to fig. 6, a schematic structural diagram of an illumination device according to a fourth embodiment of the present invention is shown in fig. 6, the illumination device 4 includes an excitation light source 41, a light guiding device 42 and a light conversion device 43, the excitation light source 41 emits excitation light with a first wavelength distribution and a smaller spot area, in this embodiment, the excitation light source 41 is a point light source emitting the excitation light with the first wavelength distribution, the light guiding device 42 is used for making the excitation light emitted by the excitation light source 41 incident on a specific position of the light conversion device 43 at a suitable angle, the light conversion device 43 is used for converting the excitation light with the smaller spot area (such as a point light source) with the first wavelength distribution into the emission light with the larger spot area (a surface light source) with the second wavelength distribution, the light conversion device 43 includes at least a light guide 44, a wavelength conversion member 45 and a reflective diffusion member 46, wherein the light guide 44 is disposed separately from the wavelength conversion member 45, the light guide 44 is disposed on the wavelength conversion member 45, the reflective diffusion member 46 is disposed at the end of the light guide 44, and the reflective diffusion member 46 and the light guide 44 promote the uniformity of the excitation light with the spot area of the excitation light with the first wavelength distribution into the emission light with the second wavelength distribution, and the emission light with the second wavelength distribution is converted into the emission light with the larger spot area. In this embodiment, the light conversion device 43 further includes a light splitting member 47, a reflecting member 48, and a heat dissipating member 49, where the arrangement of the reflecting member 48, the light splitting member 47, and the heat dissipating member 49 may be the same as or similar to those of the first, second, and third embodiments, for example, the light splitting member 47 may be a dichroic plate as in the first embodiment, the light splitting member 47 may be a reflecting element provided with a through hole as in the second embodiment, and for example, the light guiding member 44 may be a rectangular parallelepiped as in the first and second embodiments, or the light guiding member 44 may be another shape as taught in the third embodiment.

The present embodiment differs from the first, second, and third embodiments mainly in that: a scattering structure 50 is disposed on the first surface 443, i.e. the light emitting surface, of the light guide 44, where the scattering structure 50 is bonded to the light guide 44 by using a material with low refraction and high transmittance, so that the interface therebetween is in optical contact, and the scattering structure 50 may be a film containing scattering particles or a film with prisms or other rugged microstructures, where the scattering particles or microstructures may be of the same type or include two or more different types, and where the spatial distribution of the scattering particles or microstructures may be uniform or non-uniform. Thus, the light-emitting efficiency and uniformity of the lighting device 4 are further improved.

It is understood that in other embodiments, the scattering structure 50 may be omitted, and the microstructure may be directly machined or etched on the first surface 443 of the light guide 44 to form the scattering structure, so as to improve the light emitting efficiency and uniformity of the lighting device 4.

It will be appreciated that in other embodiments, a scattering structure, such as a scattering member or a microstructure, may be disposed on the second face 444 of the light guide 44, which may also improve the light extraction efficiency and uniformity of the lighting device. When the scattering member is disposed on the second face 444 of the light guide 44, the scattering member may be disposed between the second face 444 of the light guide 44 and the wavelength conversion member 45.

Referring to fig. 7, which is a schematic structural diagram of a lighting device according to a fifth embodiment of the present invention, unlike the above-mentioned embodiment, the lighting device 5 according to the present embodiment further includes a dichroic sheet 59 disposed on the first surface 543 of the light guide 54, and the dichroic sheet 59 is capable of transmitting light with one wavelength distribution (e.g. yellow light) and reflecting light with another wavelength distribution (e.g. blue light), so as to improve the purity of the light emitted from the lighting device.

It will be appreciated that dichroic sheet 59 may also be replaced by a polarizing beamsplitter.

In the above description, it can be seen that, compared with the prior art, by disposing the light guide separately from the wavelength conversion member and disposing the reflective diffusion member on the opposite end surface of the light incident surface of the light conversion device, the excitation light entering the light guide of the light conversion device does not directly enter the wavelength conversion member, but is changed in light distribution at the reflective diffusion member after being conducted by the light guide, and then enters the wavelength conversion member disposed at the second surface position between the first end and the second end of the light guide with a more uniform light distribution. On the one hand, the wavelength conversion part becomes a surface light source (which is different from a body light source of a transparent fluorescent light guide in the background technology), which is favorable for regulating and controlling the light emitting uniformity of the lighting device. In addition, compared with the background technology of a 'body light source', the wavelength conversion piece can receive uniform excitation light irradiation with a large area on the whole surface, and the excitation light power at each place is not different due to the difference of the distance from the excitation light source, so that the wavelength conversion piece can emit light and heat more uniformly.

Furthermore, by arranging the reflecting elements on the peripheral sides of the light guide and the wavelength conversion member and arranging the reflecting elements on the side, away from the light guide, of the wavelength conversion member, the extraction efficiency of the light emitted from the first surface of the light guide is ensured, namely the light emitting efficiency of the lighting device is ensured. And the side, far away from the light guide, of the wavelength conversion piece is provided with the heat dissipation piece, and the light guide adopts sapphire, so that the heat dissipation of the wavelength conversion piece is further improved.

In the above-described embodiments, the illumination device is a laser illumination device, but the illumination device of the present invention is not limited to the laser illumination device, and may include: 1. the light guide and the reflecting diffusion piece arranged at the tail end of the light guide diffuse the excitation light with smaller light spot area into the excitation light with larger light spot area, and 3. The excitation light with larger light spot area excites the wavelength conversion piece to generate emergent light, which falls within the spirit and scope of the invention.

The above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the above preferred embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A lighting device, comprising:

A light conversion device comprising:

the light guide comprises a first end, a second end opposite to the first end, and a first surface and a second surface which are connected between the first end and the second end, wherein the first end is provided with a light incident surface of the light conversion device, the excitation light is incident into the light guide through the light incident surface, the first surface forms a light emergent surface of the light conversion device, the first surface and the second surface of the light guide are opposite to each other, and the distance between the first surface and the second surface of the light guide is gradually increased from the first end to the second end of the light guide;

the reflective diffusion piece is arranged at the second end of the light guide piece and used for diffusing and reflecting the excitation light back into the light guide piece, and the reflective diffusion piece is a diffuse reflection element; and

A wavelength conversion member disposed adjacent to the second face of the light guide member for converting the excitation light into lasing light of a second wavelength distribution and reflecting the lasing light back into the light guide member and out of the first face of the light guide member;

the light guide device is arranged between the excitation light source and the light conversion device and is used for enabling excitation light emitted by the excitation light source to be incident to the light guide piece at the first end at a light divergence half angle which is smaller than 1/2 times of the length-diameter ratio reciprocal of the light guide piece.

2. The illumination device of claim 1, wherein the light conversion device further comprises a light splitting member disposed adjacent to the light entrance surface of the light conversion device, the light splitting member transmitting the excitation light of a specific angle range to the light guide member, and reflecting the excitation light of the laser light and other angle ranges.

3. The illumination device of claim 1, wherein the light conversion device further comprises a light splitting member disposed adjacent to the light entrance surface of the light conversion device, and the light splitting member is a reflective element provided with a through hole.

4. The illumination device of claim 1, wherein the light guide further comprises a peripheral side connecting the first end and the second end, the light conversion device further comprising a reflective member disposed adjacent the peripheral side, the reflective member preventing excitation light and laser light from exiting the peripheral side.

5. The illumination device of claim 1, wherein the light conversion device further comprises a heat sink disposed on a side of the wavelength conversion member remote from the light guide.

6. The illumination device of claim 1, wherein the light conversion device further comprises a scattering structure disposed or formed on the first or second face of the light guide or on both the first and second faces of the light guide.

7. The illumination device of claim 1, wherein the light guide is made of sapphire.