A light emitting device

Abstract

The present invention relates to the field of optical technology, and discloses a light-emitting device, comprising: a light source, a wavelength conversion element and a light guide, wherein the wavelength conversion element is located between the light source and the light guide; the excitation light emitted by the light source is irradiated onto the wavelength conversion element, and the wavelength conversion element absorbs at least part of the excitation light and converts it into a converted light; the converted light and the unconverted excitation light are output to the light incident surface of the light guide, enter the interior of the light guide through the light incident surface, and are output through the light exit surface of the light guide through total internal reflection; the area of ​​the light incident surface of the light guide is larger than the area of ​​the light exit surface of the light guide, and by arranging the wavelength conversion element and the light guide separately, the light guide only plays the role of light gathering and light homogenization, thereby avoiding the influence of the heat generated by the light guide as a wavelength conversion element on the performance of the light-emitting device; there is no need to consider the effect of wavelength conversion, so that the light guide has greater selectivity, universality, and is easy to achieve low-cost mass production.

Description

Technical Field

[0001] The present invention relates to the field of optical technology, and in particular to a light emitting device. Background Art

[0002] In the fields of spotlighting and projection, how to obtain high-brightness light sources, especially white light sources, has always been the focus of research. The HLD (High Lumen Density) light source developed by Philips uses highly transparent luminescent materials to convert light with shorter wavelengths into light with longer wavelengths, and extracts the longer wavelength light from a small surface, thereby breaking the conservation of optical etendue and achieving high-brightness, small optical etendue light output.

[0003] Patent EP2947484 discloses a light-emitting device, which includes at least two light sources, a waveguide and a light-emitting element located on a light-emitting surface. The waveguide is used to convert light of a first wavelength distribution emitted by a first light source into light of a third wavelength distribution and export it, and at the same time guide light of a second wavelength distribution emitted by a second light source to the light-emitting element at the light-emitting surface, and the light-emitting element converts the light of the second wavelength distribution into light of a fourth wavelength distribution and exports it, thereby achieving white light output.

[0004] Patent WO2014198619 discloses a light-emitting device with high-efficiency white light output, which includes a light source and two light guides. The first light guide guides part of the light of the first wavelength distribution emitted by the light source to the end face output, and the other part is coupled to the second light guide and converted by the second light guide into light output of the second wavelength distribution, thereby reducing light loss and achieving high-efficiency white light output.

[0005] In the prior art, light guides play two roles at the same time: focusing light and converting wavelengths. Multiple light guides are used together to achieve white light output. Since light guides also play a role in wavelength conversion, the heat caused by the Stokes shift during the wavelength conversion process accumulates inside the light guide, which affects the optical performance of the entire device. Therefore, the light guide is required to have good thermal properties. In addition, different light guides are required to achieve different colors of light output. In order to reduce light loss, the light guide is usually required to be a high-performance luminescent material that does not contain scattering particles and is highly transparent. Therefore, the light guide preparation process is complicated. Summary of the invention

[0006] The main purpose of the present invention is to provide a light-emitting device. By separately arranging the wavelength conversion element and the light guide, the light guide only plays the role of light gathering and light homogenization, thereby avoiding the influence of the heat generated by the light guide as a wavelength conversion element on the performance of the light-emitting device; there is no need to consider the effect of wavelength conversion, so that the light guide has greater selectivity, versatility, and is easy to achieve low-cost mass production.

[0007] To achieve the above object, the present invention provides a light emitting device, comprising: a light source, a wavelength conversion element and a light guide, wherein the wavelength conversion element is located between the light source and the light guide;

[0008] The excitation light emitted by the light source is irradiated onto the wavelength conversion element, and the wavelength conversion element absorbs at least part of the excitation light and converts it into converted light;

[0009] The converted light and the unconverted excitation light are output to the light incident surface of the light guide, enter the interior of the light guide through the light incident surface, and are output through the light exit surface of the light guide by total internal reflection; the area of ​​the light incident surface of the light guide is larger than the area of ​​the light exit surface of the light guide.

[0010] Optionally, the output surface of the wavelength conversion element for outputting the converted light and the unconverted excitation light is arranged opposite to the light incident surface of the light guide, and the area of ​​the output surface is equivalent to the area of ​​the light incident surface, and the size error between the two is within a preset first area threshold.

[0011] Optionally, the wavelength conversion element is a panel-shaped element, which includes the output surface and a receiving surface located at the back of the output surface;

[0012] The excitation light emitted by the light source is irradiated onto the receiving surface.

[0013] Optionally, an area of ​​the receiving surface covered by a light spot of the excitation light irradiated onto the receiving surface is greater than a preset second area threshold.

[0014] Optionally, the light source is in non-optical contact with the wavelength conversion element, and the wavelength conversion element is in non-optical contact with the light guide.

[0015] Optionally, the wavelength conversion element comprises a first wavelength conversion element and a second wavelength conversion element, and the first wavelength conversion element is in non-optical contact with the second wavelength conversion element;

[0016] The first wavelength conversion element is in non-optical contact with the light source, and the first wavelength conversion element includes a first light incident surface and a first light exit surface;

[0017] The second wavelength conversion element is in non-optical contact with the light guide, the second wavelength conversion element comprising a second light incident surface and a second light exit surface;

[0018] The excitation light enters the first wavelength conversion element through the first light incident surface, and the first wavelength conversion element absorbs at least a portion of the excitation light and converts it into a first converted light;

[0019] The first converted light and the unconverted excitation light are emitted from the first light exit surface and enter the second wavelength conversion element through the second light incident surface. The second wavelength conversion element absorbs at least part of the unconverted excitation light and / or the first converted light and converts it into the second converted light. The unconverted excitation light, the unconverted first converted light, and the second converted light are emitted from the second light exit surface and enter the light guide through the light incident surface of the light guide.

[0020] Optionally, a reflective layer is provided on part or all of the surfaces facing the light guide except the light incident surface and the light exit surface; an air gap is provided between the reflective layer and the surface it faces; and the reflective layer is a specular reflective layer or a diffuse reflective layer.

[0021] Optionally, a diffuse reflection layer is provided at a first surface of the light guide opposite to the light incident surface, and an air gap is provided between the diffuse reflection layer and the first surface.

[0022] Optionally, a mirror reflection layer is provided at a second surface of the light guide opposite to the light emitting surface, and an air gap is provided between the mirror reflection layer and the second surface.

[0023] Optionally, an optical coupling element is arranged at least at one point between the light source and the wavelength conversion element, between the wavelength conversion element and the light incident surface of the light guide, and at the light exit surface of the light guide. The optical coupling element is optically connected to the adjacent optical element, and the refractive index of the optical coupling element is lower than the refractive index of the adjacent optical element.

[0024] Optionally, an optical coupling element is arranged at least one of between the light source and the first wavelength conversion element, between the first wavelength conversion element and the second wavelength conversion element, between the second wavelength conversion element and the light incident surface of the light guide, and at the light exit surface of the light guide. The optical coupling element is optically connected to the adjacent optical element, and the refractive index of the optical coupling element is lower than the refractive index of the adjacent optical element.

[0025] Optionally, a reflective layer is provided on part or all of the surface of the wavelength conversion element except a receiving surface for receiving light and an output surface for outputting light.

[0026] Optionally, the light source is a surface light source, and the light source includes a substrate and a plurality of light-emitting chips arranged on the substrate.

[0027] Optionally, the reflectivity of the substrate is greater than 90%, and the light-emitting chip is a laser light source, an LED light source or an OLED light source.

[0028] Optionally, the light guide is a transparent light guide, and a refractive index of the light guide is greater than 1.2.

[0029] Optionally, the surface roughness of the light guide is less than 100 nm.

[0030] Optionally, the material of the light guide is YAG single crystal, sapphire, YAG transparent ceramic, Al2O3 transparent ceramic, silica gel or glass.

[0031] Optionally, a distance between the second wavelength conversion element and the light guide is in a range of 100 μm-1000 μm.

[0032] Optionally, a heat sink is disposed adjacent to a surface of part or all of the reflective layer facing away from the light guide.

[0033] A light-emitting device proposed in the present invention includes: a light source, a wavelength conversion element and a light guide, wherein the wavelength conversion element is located between the light source and the light guide; the excitation light emitted by the light source is irradiated to the wavelength conversion element, and the wavelength conversion element absorbs at least part of the excitation light and converts it into converted light; the converted light and the unconverted excitation light are output to the light incident surface of the light guide, enter the interior of the light guide through the light incident surface, and are output through the light exit surface of the light guide through total internal reflection; the area of ​​the light incident surface of the light guide is larger than the area of ​​the light exit surface of the light guide, and by separately arranging the wavelength conversion element and the light guide, the light guide only plays the role of light gathering and light homogenization, thereby avoiding the influence of the heat generated by the light guide as a wavelength conversion element on the performance of the light-emitting device; there is no need to consider the effect of wavelength conversion, so that the light guide has greater selectivity, versatility, and is easy to achieve low-cost mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic diagram of the structure and light transmission of a light emitting device provided in the first embodiment of the present invention;

[0035] Figure 2 A schematic diagram of the structure and light transmission of a light emitting device provided in the second embodiment of the present invention;

[0036] Figure 3 A schematic diagram of the structure and light transmission of a light emitting device provided in Embodiment 3 of the present invention;

[0037] Figure 4 A schematic diagram of the structure and light transmission of a light emitting device provided in Embodiment 4 of the present invention.

[0038] The accompanying drawings are marked as follows:

[0039] 1-light source, 10-substrate, 11-light emitting chip;

[0040] 2-wavelength conversion element, 21-first wavelength conversion element, 22-second wavelength conversion element, 211-first light incident surface, 212-first light exit surface, 221-second light incident surface, 222-second light exit surface;

[0041] 3-light guide, 31-light incident surface, 32-first surface, 33-light exit surface;

[0042] 41- diffuse reflection layer, 42- specular reflection layer;

[0043] 5 - reflective layer; 6 - first optical coupling element, 7 - second optical coupling element, 8 - third optical coupling element, 9 - fourth optical coupling element.

[0044] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0045] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0046] like Figure 1 As shown, in one embodiment, a light emitting device includes: a light source 1, a wavelength conversion element 2 and a light guide 3, wherein the wavelength conversion element 2 is located between the light source 1 and the light guide 3;

[0047] The excitation light emitted by the light source 1 is irradiated to the wavelength conversion element 2, and the wavelength conversion element 2 absorbs at least part of the excitation light and converts it into converted light;

[0048] The converted light and the unconverted excitation light are output to the light incident surface 31 of the light guide 3, enter the interior of the light guide 3 through the light incident surface 31, and are output through the light exit surface 33 of the light guide 3 by total internal reflection; the area of ​​the light incident surface 31 of the light guide 3 is larger than the area of ​​the light exit surface 33 of the light guide 3.

[0049] In this embodiment, by separately arranging the wavelength conversion element 2 and the light guide 3, the light guide 3 only plays the role of light gathering and light homogenization, thereby avoiding the influence of the heat generated by the light guide 3 as the wavelength conversion element 2 on the performance of the light-emitting device; there is no need to consider the effect of wavelength conversion, so that the light guide 3 has greater selectivity, versatility, and is easy to achieve low-cost mass production.

[0050] In one embodiment, the output surface of the wavelength conversion element 2 for outputting the converted light and the unconverted excitation light is arranged opposite to the light incident surface 31 of the light guide 3, and the area of ​​the output surface is equivalent to the area of ​​the light incident surface 31, and the size error between the two is within a preset first area threshold. For example, the size error between the area of ​​the output surface and the area of ​​the light incident surface is less than 1% of either one of the two.

[0051] In one embodiment, the wavelength conversion element 2 is a panel-shaped element, which includes the output surface and a receiving surface located at the back of the output surface;

[0052] The excitation light emitted by the light source 1 irradiates the receiving surface, and the light spot of the excitation light irradiating the receiving surface covers an area of ​​the receiving surface greater than a preset second area threshold. It can be understood that the light spot basically covers the receiving surface, and the uncovered area is within a preset range.

[0053] In one embodiment, the light source 1 is in non-optical contact with the wavelength conversion element 2, and the wavelength conversion element 2 is in non-optical contact with the light guide 3. In one embodiment, the non-optical contact between the two components described herein can be understood as the distance between the two components being greater than the wavelength of light transmitted between the two components. In one embodiment, the non-optical contact between the two components described herein can be understood as the distance between the two components being greater than the wavelength of visible light. In one embodiment, the non-optical contact between the two components described herein can be understood as the distance between the two components being greater than 800nm.

[0054] In one embodiment, the wavelength conversion element 2 includes a first wavelength conversion element 21 and a second wavelength conversion element 22, and the first wavelength conversion element 21 is in non-optical contact with the second wavelength conversion element 22;

[0055] The first wavelength conversion element 21 is in non-optical contact with the light source 1, and the first wavelength conversion element 21 includes a first light incident surface 211 and a first light exit surface 212; the first light incident surface 211 is the receiving surface of the wavelength conversion element mentioned above;

[0056] The second wavelength conversion element 22 is in non-optical contact with the light guide 3, and the second wavelength conversion element 22 includes a second light incident surface 221 and a second light exit surface 222; the second light exit surface 222 is the output surface of the wavelength conversion element;

[0057] The excitation light enters the first wavelength conversion element 21 through the first light incident surface 211, and the first wavelength conversion element 21 absorbs part of the excitation light and converts it into a first converted light;

[0058] The first converted light and the unconverted excitation light are emitted from the first light exit surface 212 and enter the second wavelength conversion element 22 through the second light incident surface 221. The second wavelength conversion element 22 absorbs at least part of the unconverted excitation light and / or the first converted light and converts it into the second converted light. The unconverted excitation light, the unconverted first converted light, and the second converted light are emitted from the second light exit surface 222 and enter the light guide 3 through the light incident surface 31 of the light guide 3.

[0059] As another embodiment, the number of the wavelength conversion elements 2 may be one or greater than or equal to three, which is set by the user or manufacturer according to needs.

[0060] In one embodiment, the excitation light is Figure 1 L1 in the embodiment is preferably light with a wavelength in the range of 400-500 nm, and the first stimulated light is Figure 1 The wavelength of L2 is greater than that of L1, preferably 460-560nm, for example, it can be green light, and the second stimulated light is Figure 3 In the L3, the wavelength of L3 is greater than the wavelength of L2, preferably 500-660nm, for example, it can be red light. The mixed light of L1, L2 and L3 enters the light guide 3 through the light incident surface 31, and under the action of total internal reflection, is guided to the light exit surface 33 to obtain high-brightness L1+L2+L3 mixed light.

[0061] In one embodiment, by changing parameters such as the doping concentration in the constituent material of the wavelength conversion element 2 and the thickness of the wavelength conversion element 2, the relative proportions of L1, L2, and L3 in the L1+L2+L3 mixed light can be adjusted to achieve white light output with a high color rendering index.

[0062] In one embodiment, the wavelength conversion element 2 may be made of luminescent single crystals or ceramics, inorganic phosphors, organic phosphors, organic fluorescent dyes, luminescent quantum dots, etc., which are packaged in glass or silica gel.

[0063] In one embodiment, the light source 1 is a surface light source, and the light source 1 includes a substrate 10 and a plurality of light-emitting chips 11 arranged on the substrate 10. The substrate 10 is made of a high-reflectivity material, and the reflectivity of the substrate 10 is greater than 90%, and can also act as a heat sink. The light-emitting chip 11 is a laser light source, an LED light source, or an OLED light source.

[0064] In one embodiment, the light guide 3 is a transparent non-wavelength conversion light guide 3, which is made of a material that is transparent in the visible light region, such as YAG single crystal, sapphire, YAG transparent ceramics, Al2O3 transparent ceramics, organic polymers such as silicone, glass, etc. In order to increase the total reflection of the incident light at the interface between the light guide 3 and the surrounding medium, the light guide 3 is preferably made of a high refractive index material. The refractive index of the light guide 3 is greater than 1.2, preferably greater than 1.5, and the surface roughness of the light guide 3 is less than 100nm, preferably less than 50nm.

[0065] In one embodiment, the distance between the second wavelength conversion element 22 and the light guide 3 is in the range of 50 μm-2000 μm. Preferably, the distance between the second wavelength conversion element 22 and the light guide 3 is in the range of 100 μm-1000 μm. A distance that is too small is not conducive to heat dissipation, and a distance that is too large will increase the size of the light emitting device.

[0066] In one embodiment, a reflective layer 5 is provided on part or all of the surfaces facing the light guide 3 except the light incident surface 31 and the light exit surface 33 ; an air gap is provided between the reflective layer 5 and the surface it faces; the reflective layer 5 is a mirror reflection layer 42 or a diffuse reflection layer 41 .

[0067] In one embodiment, the light guide 3 is a hexahedron, and except for the light incident surface 31 and the light emitting surface 33 , the other four surfaces may be provided with the reflective layer 5 .

[0068] In one embodiment, a diffuse reflection layer 41 is disposed at the first surface 32 of the light guide 3 opposite to the light incident surface 31 , and an air gap is disposed between the diffuse reflection layer 41 and the first surface 32 .

[0069] In one embodiment, a mirror reflection layer 42 is disposed at a second surface of the light guide 3 opposite to the light exit surface 33 , and an air gap is disposed between the mirror reflection layer 42 and the second surface.

[0070] In one embodiment, by Figure 2 It can be seen that the light incident surface 31 and the light exit surface 33 of the light guide 3 are not opposite to each other but perpendicular to each other, and the surface opposite to the light incident surface 31 is the first surface 32, and the surface opposite to the light exit surface 33 is the second surface.

[0071] The reflectivity of the diffuse reflection layer 41 is greater than 90%; an air gap is provided between the diffuse reflection layer 41 and the first surface 32, that is, non-optical contact, because the diffuse reflection layer 41 has a certain absorption rate. If the diffuse reflection layer 41 is directly provided in optical contact with the first surface 32, the diffuse reflection layer 41 will absorb more light; and if an air gap is provided between the diffuse reflection layer 41 and the first surface 32, part of the light has been reflected back into the light guide 3 by the first surface 32, and only the emitted part of the light will irradiate the diffuse reflection layer 41, which can reduce the absorption of the diffuse reflection layer 41. The air gap is provided between the diffuse reflection layer 41 and the first surface 32, which is equivalent to having two layers of protection, the first layer is the reflection of the first surface 32 of the light guide 3, and the second layer is the diffuse reflection layer 41.

[0072] The diffuse reflection layer 41 can reduce the light escaping from the surfaces other than the light incident surface 31 and the light emitting surface 33 of the light guide 3 , and improve the intensity of the white light emitted from the light emitting surface 33 .

[0073] The reflectivity of the mirror reflection layer 42 is greater than 95%, and there is no optical contact between the mirror reflection layer 42 and the second surface. The reason is the same as above and will not be elaborated here.

[0074] In one embodiment, an optical coupling element is provided at least one of between the light source 1 and the wavelength conversion element 2, between the wavelength conversion element 2 and the light incident surface 31 of the light guide 3, and at the light exit surface 33 of the light guide 3. The optical coupling element is optically connected to the adjacent optical element, and the refractive index of the optical coupling element is lower than the refractive index of the adjacent optical element.

[0075] In one embodiment, the area between the light source 1 and the wavelength conversion element 2 can also be understood as being between the light source 1 and the receiving surface of the wavelength conversion element 2; the area between the wavelength conversion element 2 and the light incident surface 31 of the light guide 3 can also be understood as being between the output surface of the wavelength conversion element 2 and the light incident surface 31 of the light guide 3; the light source 1, the wavelength conversion element 2 and the light guide 3 are all optical elements.

[0076] In one embodiment, an optical coupling element is provided at least one of between the light source 1 and the first wavelength conversion element 21, between the first wavelength conversion element 21 and the second wavelength conversion element 22, between the second wavelength conversion element 22 and the light incident surface 31 of the light guide 3, and at the light exit surface 33 of the light guide 3. The optical coupling element is optically connected to the adjacent optical element, and the refractive index of the optical coupling element is lower than the refractive index of the adjacent optical element.

[0077] In this embodiment, the function of the optical coupling element is to couple more incident light L1 into the wavelength conversion element 2, and to allow more mixed light L1+L2+L3 to be emitted from the wavelength conversion element 2, and to be guided through the light guide 3 to the light emitting surface 33 of the light guide 3. Through the optical coupling element, the light output efficiency is further improved to obtain high-brightness white light.

[0078] In one embodiment, the optical coupling element can be a lens or a lens array, or a coupling structure. The optical coupling element can be set at any one or more of the above-mentioned optical coupling element installation positions. Preferably, an optical coupling element is set at each position, so as to maximize the light extraction efficiency.

[0079] In one embodiment, Figure 3 As shown, the optical coupling element between the light source 1 and the first wavelength conversion element 21 is the first optical coupling element 6, the optical coupling element between the first wavelength conversion element 21 and the second wavelength conversion element 22 is the second optical coupling element 7, the optical coupling element between the second wavelength conversion element 22 and the light guide 3 is the third optical coupling element 8, and the optical coupling element on the light exit surface 33 of the light guide 3 is the fourth optical coupling element 9; the refractive index of each optical coupling element is related to the refractive index of the light source 1, the wavelength conversion element 2 and the light guide 3. Preferably, the refractive index of the first optical coupling element 6 is lower than the refractive index of the light source 1 and the first wavelength conversion element 21, the refractive index of the second optical coupling element 7 is lower than the refractive index of the first wavelength conversion element 21 and the second wavelength conversion element 22, the refractive index of the third optical coupling element 8 is lower than the refractive index of the second wavelength conversion element 22 and the light guide 3, and the refractive index of the fourth optical coupling element 9 is lower than the refractive index of the light guide 3.

[0080] like Figure 4 As shown, in one embodiment, a reflective layer 5 is provided on part or all of the surface of the wavelength conversion element 2 except the receiving surface for receiving light and the output surface for outputting light; the reflective layer 5 is located on at least one side surface of the wavelength conversion element 2, and the side surface is perpendicular to the light incident surface 31 and the light exit surface 33 of the wavelength conversion element 2.

[0081] In one embodiment, the reflective layer 5 is specularly reflective or diffusely reflective, the reflective layer 5 is in non-optical contact with the wavelength conversion element 2 , and the reflectivity is greater than 90%.

[0082] like Figure 4 As shown, the reflective layer 5 can be arranged on two non-light exiting and incident surfaces of the wavelength conversion element 2, or can be arranged on all four non-light exiting and incident surfaces.

[0083] As another embodiment, the reflective layer 5 can also be disposed on a heat sink of the light emitting device to improve the heat dissipation function of the wavelength conversion element 2; the so-called heat sink means that its temperature does not change with the amount of heat energy transferred to it, and it can be an object such as the atmosphere and the earth. In current LED lighting packages, since LEDs generate high heat when emitting light, copper columns with high thermal conductivity are used to direct the heat to the outside of the package. This LED copper column is also called a heat sink.

[0084] In one embodiment, a heat sink is disposed adjacent to a surface of part or all of the reflective layer 5 facing away from the light guide 3 .

[0085] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0086] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0087] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, a magnetic disk, or an optical disk), and includes a number of instructions for enabling a terminal device (which can be a mobile phone, a computer, a server, an air conditioner, or a network device, etc.) to execute the methods described in each embodiment of the present invention.

[0088] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A light emitting device, characterized in that: include: A light source, a wavelength conversion element and a light guide, wherein the wavelength conversion element is located between the light source and the light guide; the wavelength conversion element is arranged separately from the light guide; The excitation light emitted by the light source is irradiated onto the wavelength conversion element, and the wavelength conversion element absorbs at least part of the excitation light and converts it into converted light; The converted light and the unconverted excitation light are output to the light incident surface of the light guide, enter the interior of the light guide through the light incident surface, and are output through the light exit surface of the light guide through total internal reflection; the area of ​​the light incident surface of the light guide is larger than the area of ​​the light exit surface of the light guide; the light source is a laser light source, an LED light source, or an OLED light source.

2. The light emitting device according to claim 1, characterized in that: The output surface of the wavelength conversion element for outputting the converted light and the unconverted excitation light is arranged opposite to the light incident surface of the light guide, and the area of ​​the output surface is equivalent to the area of ​​the light incident surface, and the size error between the two is within a preset first area threshold.

3. The light emitting device according to claim 2, characterized in that: The wavelength conversion element is a panel-shaped element, which includes the output surface and a receiving surface located at the back of the output surface; The excitation light emitted by the light source is irradiated onto the receiving surface.

4. The light emitting device according to claim 3, characterized in that: The area of ​​the receiving surface covered by the light spot of the excitation light irradiating the receiving surface is greater than a preset second area threshold.

5. The light emitting device according to claim 1, characterized in that: The light source is in non-optical contact with the wavelength conversion element, and the wavelength conversion element is in non-optical contact with the light guide; non-optical contact means that the distance between the two components is greater than the wavelength of light conducted between the two components.

6. The light emitting device according to claim 1, characterized in that: The wavelength conversion element comprises a first wavelength conversion element and a second wavelength conversion element, wherein the first wavelength conversion element is in non-optical contact with the second wavelength conversion element; The first wavelength conversion element is in non-optical contact with the light source, and the first wavelength conversion element includes a first light incident surface and a first light exit surface; The second wavelength conversion element is in non-optical contact with the light guide, the second wavelength conversion element comprising a second light incident surface and a second light exit surface; the non-optical contact means that the distance between the two components is greater than the wavelength of light transmitted between the two components; The excitation light enters the first wavelength conversion element through the first light incident surface, and the first wavelength conversion element absorbs at least a portion of the excitation light and converts it into a first converted light; The first converted light and the unconverted excitation light are emitted from the first light exit surface and enter the second wavelength conversion element through the second light incident surface. The second wavelength conversion element absorbs at least part of the unconverted excitation light and / or the first converted light and converts it into the second converted light. The unconverted excitation light, the unconverted first converted light, and the second converted light are emitted from the second light exit surface and enter the light guide through the light incident surface of the light guide.

7. The light emitting device according to claim 1, characterized in that: A reflective layer is arranged on part or all of the surfaces facing the light guide except the light incident surface and the light emitting surface; an air gap is arranged between the reflective layer and the surface it faces; the reflective layer is a specular reflective layer or a diffuse reflective layer.

8. The light emitting device according to claim 7, characterized in that: A diffuse reflection layer is disposed at a first surface of the light guide opposite to the light incident surface, and an air gap is disposed between the diffuse reflection layer and the first surface.

9. The light emitting device according to claim 7, characterized in that: A specular reflection layer is disposed at a second surface of the light guide opposite to the light emitting surface, and an air gap is disposed between the specular reflection layer and the second surface.

10. The light emitting device according to claim 1, characterized in that: An optical coupling element is arranged at least one of between the light source and the wavelength conversion element, between the wavelength conversion element and the light incident surface of the light guide, and at the light exit surface of the light guide. The optical coupling element is optically connected to the adjacent optical element, and the refractive index of the optical coupling element is lower than the refractive index of the adjacent optical element.

11. The light emitting device according to claim 6, characterized in that: An optical coupling element is arranged at least one of between the light source and the first wavelength conversion element, between the first wavelength conversion element and the second wavelength conversion element, between the second wavelength conversion element and the light incident surface of the light guide, and at the light exit surface of the light guide. The optical coupling element is optically connected to the adjacent optical element, and the refractive index of the optical coupling element is lower than the refractive index of the adjacent optical element.

12. The light emitting device according to claim 1, characterized in that: A reflective layer is provided on part or all of the surface of the wavelength conversion element except a receiving surface for receiving light and an output surface for outputting light.

13. The light emitting device according to claim 1, characterized in that: The light source is a surface light source, and comprises a substrate and a plurality of light emitting chips arranged on the substrate.

14. The light emitting device according to claim 13, characterized in that: The reflectivity of the substrate is greater than 90%.

15. The light emitting device according to claim 1, characterized in that: The light guide is a transparent light guide, and the refractive index of the light guide is greater than 1.

2.

16. The light emitting device according to claim 1, characterized in that: The surface roughness of the light guide is less than 100 nm.

17. The light emitting device according to claim 1, characterized in that: The material of the light guide is YAG single crystal, sapphire, YAG transparent ceramic, Al2O3 transparent ceramic, silica gel or glass.

18. The light emitting device according to claim 6, characterized in that: The distance between the second wavelength conversion element and the light guide is in the range of 50 μm-2000 μm.

19. The light emitting device according to claim 18, characterized in that: The distance between the second wavelength conversion element and the light guide is in the range of 100 μm-1000 μm.

20. The light emitting device according to claim 7, characterized in that: A heat sink is arranged adjacent to a surface of part or all of the reflective layer facing away from the light guide.

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