A wavelength conversion unit and laser lighting module

Abstract

The present invention discloses a wavelength conversion unit and a laser lighting module, the wavelength conversion unit comprises a phosphor sheet and a heat-conducting substrate arranged in sequence, the phosphor sheet comprises a first surface corresponding to the heat-conducting substrate and a second surface away from the heat-conducting substrate, the first surface is a smooth surface, the second surface is a rough surface, and the rough surface is coated with a diffuse reflection material that can reflect excitation light. The first surface is set as a smooth surface, the second surface is set as a rough surface, and the diffuse reflection material that can reflect excitation light is coated on the rough surface, so that a part of the incident excitation light can be reflected back, and only a part of the excitation light is allowed to enter the phosphor sheet and converted into a stimulated light. By controlling the area size and thickness of the diffuse reflection material covering the second surface, the proportion of the excitation light reflected back can be controlled, so that the amount of reflected excitation light can be accurately controlled to mix and form white light, thereby improving the lighting effect.

Description

Technical Field

[0001] The present invention relates to the field of lighting technology, and in particular to a wavelength conversion unit and a laser lighting module. Background Art

[0002] Using laser to excite remote phosphor to generate white light can obtain ultra-high brightness light source, which is widely used in special lighting fields such as projection display and car headlights. In the reflective excitation structure, the laser is incident on the fluorescent conversion material, and the stimulated light emitted from the fluorescent conversion material and the reflected excitation light (unconverted excitation light) are mixed to form white light.

[0003] In order to obtain ideal white light, the reflected excitation light must reach a certain ratio, usually the energy ratio of the excitation light to the converted light must be more than 20%. However, since the absorption rate of the excitation light by the fluorescent conversion material is very high, the converted light incident on the fluorescent conversion material will be basically completely absorbed and it is difficult to reflect it back. In order to increase the reflected excitation light, the current common method is to add scattering particles inside the fluorescent conversion material to ensure that a certain amount of excitation light is reflected back.

[0004] However, the addition of scattering particles will affect the performance of the fluorescent conversion material, for example, reducing thermal conductivity, or reducing conversion efficiency.

[0005] In addition, the yellow light output from the fluorescent conversion material usually has a Lambertian distribution in terms of spatial intensity distribution. In order to obtain spatially uniform white light, the reflected excitation light is required to have the same intensity distribution, which increases the technical difficulty. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides a wavelength conversion unit and a laser lighting module for improving lighting effects.

[0007] In order to solve the above technical problems, the technical solution of the present invention is:

[0008] A wavelength conversion unit comprises a phosphor sheet and a heat-conducting substrate arranged in sequence, wherein the phosphor sheet comprises a first surface corresponding to the heat-conducting substrate and a second surface away from the heat-conducting substrate, wherein the first surface is a smooth surface and the second surface is a rough surface, and the rough surface is coated with a diffuse reflection material that can reflect excitation light.

[0009] Furthermore, a texture structure is provided on the second surface.

[0010] Furthermore, the texture structure includes a plurality of grooves, and the depth of the grooves is 30-50 um.

[0011] Furthermore, the diffuse reflection material does not completely cover the second surface.

[0012] Furthermore, the diffuse reflection material includes scattering particles and a bonding material for bonding the scattering particles.

[0013] Furthermore, the scattering particles are aluminum oxide, titanium oxide, zirconium oxide or barium sulfate, and the bonding material is silica gel, glue or glass matrix.

[0014] Furthermore, a reflective film is coated on one side of the thermally conductive substrate corresponding to the phosphor sheet.

[0015] Furthermore, the side of the phosphor sheet corresponding to the thermal conductive substrate is coated with a reflective film.

[0016] Furthermore, the side of the fluorescent powder sheet different from the first surface and the second surface is coated with white wall glue.

[0017] The present invention also provides a laser lighting module, comprising a laser light source and the wavelength conversion unit as described above, wherein the laser light source emits excitation light and projects it onto the second surface of the phosphor sheet.

[0018] The wavelength conversion unit and laser lighting module provided by the present invention include a phosphor sheet and a heat-conducting substrate arranged in sequence, the phosphor sheet includes a first surface corresponding to the heat-conducting substrate and a second surface away from the heat-conducting substrate, the first surface is a smooth surface, the second surface is a rough surface, and the rough surface is coated with a diffuse reflection material that can reflect the excitation light. The first surface is set as a smooth surface, the second surface is set as a rough surface, and the diffuse reflection material that can reflect the excitation light is coated on the rough surface, so that a part of the incident excitation light can be reflected back, and only a part of the excitation light is allowed to enter the phosphor sheet and be converted into the excited light. By controlling the area size and thickness of the diffuse reflection material covering the second surface, the proportion of the excitation light reflected back can be controlled, so that the amount of the reflected excitation light can be accurately controlled to mix and form white light, thereby improving the lighting effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic structural diagram of a specific embodiment of a wavelength conversion unit of the present invention;

[0020] Figure 2 It is a structural schematic diagram of a specific embodiment of the laser lighting module of the present invention.

[0021] As shown in the figure: 10, phosphor sheet; 110, first surface; 120, second surface; 20, thermal conductive substrate; 30, diffuse reflection material; 40, groove; 50, white wall glue; 60, laser light source. DETAILED DESCRIPTION

[0022] The present invention is described in detail below in conjunction with the accompanying drawings:

[0023] like Figure 1 As shown, the present invention provides a wavelength conversion unit, including a phosphor sheet 10 and a thermal conductive substrate 20 arranged in sequence, the phosphor sheet 10 includes a first surface 110 corresponding to the thermal conductive substrate 20 and a second surface 120 away from the thermal conductive substrate 20, the first surface 110 is a smooth surface, the second surface 120 is a rough surface, and the rough surface is coated with a diffuse reflection material 30 that can reflect excitation light. Specifically, the phosphor sheet 10 can be made of a fluorescent ceramic sheet or a fluorescent glass sheet, wherein the fluorescent ceramic sheet has better heat resistance and can avoid being easily burned due to excessive temperature. The phosphor sheet 10 has two main optical surfaces, namely a first surface 110 corresponding to the thermal conductive substrate 20 and a second surface 120 away from the thermal conductive substrate 20, wherein the first surface 110 is a smooth surface, which can improve the total internal reflection rate and make the light emit from the second surface 120, and the second surface 120 is a rough surface, which can reduce the total internal reflection rate of the converted light, make the converted light emit from the second surface 120, and improve the light output rate. A diffuse reflection material 30 that can reflect the excitation light is coated on the rough surface, which can reflect a part of the incident excitation light back and only allow a part of the excitation light to enter the phosphor sheet 10 and be converted into the converted light. The diffuse reflection material 30 may not completely cover the second surface 120. By controlling the area size and thickness of the diffuse reflection material 30 covering the second surface 120, the proportion of the excitation light reflected back can be controlled, so that the amount of the reflected excitation light can be accurately controlled to mix and form white light, thereby improving the lighting effect. In this embodiment, the excitation light is blue light, and the phosphor in the phosphor sheet 10 is yellow phosphor. Of course, the excitation light can also be yellow light, and the phosphor in the phosphor sheet 10 is red phosphor. The thermal conductive substrate 20 is preferably a substrate with high thermal conductivity and high reflectivity, and can be a metal substrate, such as an aluminum plate, a copper plate or other highly reflective metal plate. Of course, a ceramic substrate can also be used, which has better thermal conductivity.

[0024] In order to improve the reflectivity of the stimulated light, a reflective film (not shown in the figure) is coated on one side of the thermal conductive substrate 20 corresponding to the phosphor sheet 10. Of course, a reflective film can also be coated on the first surface 110 corresponding to the phosphor sheet 10 and the thermal conductive substrate 20. The reflective film is a metal silver film or a dielectric film, and the most commonly used is a silver-plated aluminum plate, so that the light transmitted from the phosphor sheet 10 to the first surface 110 is reflected back and finally emitted from the second surface 120, thereby improving the light extraction efficiency.

[0025] Preferably, the diffuse reflection material 30 does not completely cover the second surface 120. Specifically, the diffuse reflection material 30 may completely cover the second surface 120, or may not completely cover the second surface 120, but only cover a part of the area. A part of the incident blue light can be reflected back by the diffuse reflection material 30, and only a part of the blue light is allowed to enter the phosphor sheet 10. The blue light entering the phosphor sheet is converted into yellow light by the fluorescent material and then emitted. The basic characteristics of the diffuse reflection material 30 are: it does not absorb light, or the absorption of light is very small, and it can form a certain backscattering of light, which is convenient for coating operation and can accurately control its amount. By controlling the thickness of the diffuse reflection material 30, or the size of the area covering the phosphor sheet 10, the proportion of the blue light reflected back can be controlled, so that the amount of the reflected blue light can be accurately controlled to mix and form white light. Preferably, the diffuse reflection material 30 includes scattering particles and a bonding material for bonding the scattering particles. The scattering particles can be white granular particles such as aluminum oxide, titanium oxide, zirconium oxide, barium sulfate, etc. The bonding material can be silica gel or transparent glue or glass matrix, etc.

[0026] Preferably, a texture structure is provided on the second surface 120, and the texture structure can better roughen the second surface 120. Roughening the second surface 120 can reduce the total internal reflection of light on the second surface 120, improve the light extraction efficiency, make more stimulated light output from the rough surface, and improve the light output rate and lighting brightness. Preferably, the texture structure includes a plurality of grooves 40, the depth of the grooves 40 is 30-50um, the groove pattern can be processed by laser etching, and the diffuse reflection material 30 is coated in the grooves 40. By processing the grooves 40, on the one hand, the second surface 120 can be roughened, and on the other hand, the amount of the diffuse reflection material 30 can be controlled by controlling the depth of the grooves, so as to accurately control the excitation light reflected back and ensure the lighting effect. It should be noted that the thickness of the phosphor sheet 10 is usually less than 0.2mm. If the grooves are deep enough, they can also penetrate the entire phosphor sheet 10 from top to bottom. At this time, the phosphor sheet 10 becomes a discontinuous small block, and the diffuse reflection material 30 is filled in the gap.

[0027] Please continue to refer to Figure 1 The side of the phosphor sheet 10 different from the first surface 110 and the second surface 120 is covered with white wall glue 50. Specifically, the white wall glue 50 can be made of a mixture of silica gel and white oxide particles, surrounding the phosphor sheet 10, reflecting the light output from the four sides of the phosphor sheet 10 back into the phosphor sheet 10, and finally all of them are emitted from the second surface 120 of the phosphor sheet.

[0028] like Figure 1As shown, the present invention also provides a laser lighting module, including a laser light source 60 and a wavelength conversion unit as described above, wherein the laser light source 60 emits excitation light and projects it onto the second surface 120 of the phosphor sheet 10, and the laser light source 60 can be a blue laser diode that emits blue excitation light, in which case the phosphor in the phosphor sheet 10 is yellow phosphor, or the laser light source 60 can be a yellow laser diode that emits yellow excitation light, in which case the phosphor in the phosphor sheet 10 is red phosphor.

[0029] The present invention provides a wavelength conversion unit, comprising a phosphor sheet 10 and a thermally conductive substrate 20 arranged in sequence, wherein the phosphor sheet 10 comprises a first surface 110 corresponding to the thermally conductive substrate 20 and a second surface 120 away from the thermally conductive substrate 20, wherein the first surface 110 is a smooth surface, and the second surface 120 is a rough surface, and the rough surface is coated with a diffuse reflection material 30 that can reflect excitation light. The phosphor sheet 10 has two main optical surfaces, namely a first surface 110 corresponding to the thermally conductive substrate 20 and a second surface 120 away from the thermally conductive substrate 20, wherein the first surface 110 is a smooth surface, which can improve the total internal reflection rate and make the light emerge from the second surface 120, and the second surface 120 is a rough surface, which can reduce the total internal reflection rate of the converted light, make the converted light emerge from the second surface 120, and improve the light output rate, and a diffuse reflection material 30 that can reflect the excitation light is coated on the rough surface, which can reflect a part of the incident excitation light back and only allow a part of the excitation light to enter the phosphor sheet 10 and be converted into the converted light, and the diffuse reflection material 30 may not completely cover the second surface 120, and the proportion of the excitation light reflected back can be controlled by controlling the area size and thickness of the second surface 120 covered by the diffuse reflection material 30, so that the amount of the reflected excitation light can be accurately controlled to mix and form white light, thereby improving the lighting effect.

[0030] Although the embodiments of the present invention are described in the specification, these embodiments are only for reference and should not limit the protection scope of the present invention. Various omissions, substitutions and changes within the scope of the present invention should be included in the protection scope of the present invention.

Claims

1. A wavelength conversion unit, characterized in that: It comprises a phosphor sheet and a heat-conducting substrate arranged in sequence, wherein the phosphor sheet comprises a first surface corresponding to the heat-conducting substrate and a second surface away from the heat-conducting substrate, wherein the first surface is a smooth surface, and the second surface is a rough surface, and the rough surface is coated with a diffuse reflection material capable of reflecting excitation light; A texture structure is provided on the second surface, and the texture structure includes a plurality of grooves, and the depth of the grooves is 30-50um; the diffuse reflection material does not completely cover the second surface, and the diffuse reflection material includes scattering particles and a bonding material for bonding the scattering particles, and the scattering particles are aluminum oxide, titanium oxide, zirconium oxide or barium sulfate, and the bonding material is silica gel, glue or a glass matrix.

2. The wavelength conversion unit according to claim 1, characterized in that: A reflective film is plated on one side of the thermally conductive substrate corresponding to the phosphor sheet.

3. The wavelength conversion unit according to claim 1, characterized in that: A reflective film is plated on one side of the fluorescent powder sheet corresponding to the heat-conducting substrate.

4. The wavelength conversion unit according to claim 1, characterized in that: The side of the fluorescent powder sheet different from the first surface and the second surface is covered with white wall glue.

5. A laser lighting module, characterized in that: It comprises a laser light source and a wavelength conversion unit as claimed in any one of claims 1 to 4, wherein the laser light source emits excitation light and projects it onto the second surface of the phosphor sheet.

Images