White laser light source

Abstract

The invention relates to a white laser light source which is characterized by comprising a laser diode module, a first lens, a first reflecting sheet, a diffusion sheet, a second reflecting sheet, a second lens, a wavelength conversion sheet, a pressing sheet, a gasket, a laser diode fixing base, a reflecting main body base, a glass window and a protective cover plate. The laser diode emits monochromatic laser under the action of impressed current, the monochromatic laser passes through the first lens, the first reflection sheet, the diffusion sheet and the second reflection sheet, is focused by the second lens and irradiates the wavelength conversion sheet to excite a fluorescent material in the wavelength conversion sheet so as to generate white light, and the white light is converged by the second lens and then is output from the glass window. The light source has the advantages of being compact in structure, high in conversion efficiency, convenient to assemble and the like, and can be applied to various occasions such as automobile illumination, projection display, machine vision and microscopic observation.

Description

Technical Field

[0001] The invention is a white laser light source, which is used in the fields of lighting and display. Background Art

[0002] The light source technology based on laser excitation fluorescence, that is, relying on the monochromatic light generated by the laser diode to excite the fluorescent material to produce white light, also known as white laser, is gaining more and more widespread applications. According to the different optical paths of the laser irradiating the fluorescent material to produce white light, the structure of the white laser light source can be divided into two types: transmission type and reflection type. Although the transmission type white laser light source has a simple structure, the heat dissipation condition of the fluorescent material is not good due to the fixing method of the fluorescent material, which affects the conversion efficiency of the laser to white light; especially when a high-power laser is used as the excitation light source, the fluorescent material may fail directly due to poor thermal conductivity under the irradiation of the high-energy density laser. On the other hand, since the fluorescent material of the reflection type white laser light source can be directly attached to the metal heat sink, when it is irradiated by the laser, the heat generated can be better discharged, so that it has a higher blue light-white light conversion efficiency than the transmission type, further improving the overall efficiency of the light source. Summary of the invention

[0003] The invention is a white laser light source, characterized in that it includes a laser diode module, a first lens, a first reflector, a diffuser, a second reflector, a second lens, a wavelength conversion sheet, a pressing sheet, a gasket, a laser diode fixing base, a reflective body base, a glass window, and a protective cover. The laser diode emits monochromatic laser light under the action of an external current, and after passing through the first lens, the first reflector, the diffuser, and the second reflector, it is focused by the second lens and irradiated onto the wavelength conversion sheet to excite the fluorescent material in the latter and generate white light, which is then converged by the second lens and output from the glass window.

[0004] Furthermore, the centers of the laser diode module, the first lens, and the first reflector are located on the same vertical axis.

[0005] Furthermore, the centers of the first reflection sheet, the diffusion sheet and the second reflection sheet are located on the same horizontal axis.

[0006] Furthermore, the centers of the second reflective sheet, the second lens and the wavelength conversion sheet are located on the same vertical axis.

[0007] Furthermore, the laser diode module is composed of 1-10 laser diodes, and the emission wavelength thereof is between 430nm-470nm.

[0008] Furthermore, the first lens is located behind the laser diode module and before the first reflector, has a diameter between 8 mm and 30 mm, and a focal length between 15 mm and 50 mm.

[0009] Furthermore, the first reflective sheet is located behind the first lens and before the diffusion sheet, has a thickness between 0.5 mm and 2 mm, and has a reflectivity greater than 90% for blue light with a wavelength of 430 nm to 470 nm.

[0010] Furthermore, the diffusion sheet is located behind the first reflection sheet and before the second reflection sheet, and the diffusion angle of the diffusion sheet to the laser is between 0.5°-5°, and the thickness is between 0.3mm-2.0mm.

[0011] Furthermore, the second reflective sheet is located behind the diffuser and before the second lens, and only the central area thereof reflects the blue light with a wavelength of 430nm-470nm, and the transmittance of the remaining part to the light with a wavelength of 400nm-750nm is greater than 90%, and the area of ​​the central area that reflects the blue light is 0.5mm 2 -9mm 2 between.

[0012] Furthermore, the second lens is located behind the second reflective sheet and before the wavelength conversion sheet, has a diameter between 4 mm and 12 mm, and a focal length between 2 mm and 8 mm.

[0013] Furthermore, the fluorescent material contained in the wavelength conversion sheet is one or more combinations of the following materials: YAG-Ce-based fluorescent material, LuAG-Ce-based fluorescent material, or oxynitride fluorescent material, which can convert laser light with a wavelength between 430nm-470nm into fluorescence with a wavelength between 400nm-700nm.

[0014] Furthermore, the reflective body base integrates all optical elements into one and serves as a reference for all elements.

[0015] The present invention has the following beneficial effects:

[0016] (1) Compact structure: The distance between each component unit is small, and the special optical path design makes the space required for the structure small, the overall volume of the light source is small, and the application environment is diversified; (2) Precise optical path: The installation and positioning of the light source and optical components are referenced to the same main component, with high positioning accuracy; (3) High conversion efficiency: The overall light energy loss of the laser before reaching the wavelength conversion plate is small, ensuring the overall efficiency of the light source; (4) Easy assembly: The overall number of component units of the light source is small, there are no movable positioning components, and each component has a base to support it, making the component installation convenient and stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the principle of a reflective white laser light source.

[0018] Figure 2Schematic diagram of the working principle of the incident laser beam and the wavelength conversion plate.

[0019] Figure 3 Schematic diagram of the incident laser beam shaping process.

[0020] Figure 4 A schematic diagram of the optical path system of a white laser light source designed for the present invention.

[0021] Figure 5 Schematic diagram of the structure of the light source for exciting fluorescence with a single laser diode.

[0022] Figure 6 Schematic diagram of the reflective body base in the light source for single laser diode fluorescence excitation.

[0023] Figure 7 This is a schematic diagram of the structure of a second reflector that is partially coated on a single piece.

[0024] Figure 8 The figure is a schematic diagram of the structure of the second reflector formed by gluing two pieces of glass together.

[0025] Fig. 9 This is a schematic diagram of the optical path system of the light source after the second reflector made of two pieces of glass is used in the present invention.

[0026] Fig.10 It is a schematic diagram of the structure of the wavelength conversion sheet used in the present invention.

[0027] Fig.11 Schematic diagram of the light source structure using a laser module array instead of a single laser diode. DETAILED DESCRIPTION

[0028] The following are specific embodiments of the present invention, and the technical solutions of the present invention are further described in conjunction with the accompanying drawings, but the present invention is not limited to these embodiments.

[0029] Generally, the excitation light path of a reflective white laser source is as follows: Figure 1 As shown, it mainly includes a laser diode (101) that generates monochromatic laser light under the action of an external current and a wavelength conversion plate (102). Under the action of the external current, a monochromatic laser beam (103) emitted by the laser diode (101) irradiates the surface of the wavelength conversion plate, reacts with the fluorescent material in the wavelength conversion plate, generates light of different wavelengths, and after being reflected by the bottom layer, is output from the same surface where the laser light is incident at multiple different angles.

[0030] The interaction between the incident laser beam and the wavelength converter can be explained by Figure 2Schematically, a represents the spot width formed by the incident laser beam on the surface of the conversion plate, and b represents the spot width formed by the output light beam after the wavelength conversion plate. After the incident laser beam (201) irradiates the fluorescent material (202) of the wavelength conversion plate, it reacts with the fluorescent material, resulting in a larger spot size of the output light (203). Obviously, the larger the a of the incident light beam, the larger the b of the output light beam. Therefore, the geometric size and shape of the output light beam can be controlled by controlling the geometric size and shape of the incident laser beam.

[0031] Reference Figure 3 , the light emitted from the laser diode (301) first passes through the lens (302), and its divergence along the fast axis and the slow axis is well suppressed. Specifically, its divergence angle is reduced to within 1-2 degrees. Then, it enters the lens (303) for focusing. In order to achieve the collimation effect, the distance between the lens (302) and the laser diode needs to be greater than its focal length. The function of the lens (303) is to focus the collimated light beam onto the wavelength conversion plate (305), so its focal length needs to be selected according to the position of the wavelength conversion plate. The distance between the lens (302) and the lens (303) is as small as possible to reduce the optical path loss and reduce the volume of the optical system. However, the actual distance between the laser diode (301) and the wavelength conversion plate (305) is much farther than the actual distance from the focusing lens (303), so a focusing lens (304) is added near the surface of the wavelength conversion plate (305) to further focus.

[0032] The principle diagram of the light source designed by the present invention is as follows Figure 4 As shown, after the laser is generated by the laser diode (including the collimating lens) (401), it passes through the first lens (402) and is reflected for the first time at the first reflector (403). After the light passes through the diffuser (404) in the horizontal direction, it is reflected for the second time at the second reflector (405). The light is focused vertically downward by the second lens (406) to the wavelength conversion plate (407), undergoes wavelength conversion and is reflected for the third time. The light is collected by the second lens and output outward.

[0033] Figure 5 Based on Figure 4The structure diagram of the white laser light source with the optical path design is shown in FIG. The laser diode fixing base (501) and the reflective body (503) are fastened by positioning columns and screws, and the protective cover (505) is also positioned together with the reflective body by screws, thereby ensuring the stability of the light source structure. The first reflector (506) and the second reflector (509) are respectively fixed on the positioning boss at the upper end of the reflective body base (503). The laser beam emitted by the laser diode (502) passes through the first lens (504), the first reflector (506), the diffuser (507), the second reflector (509), and the second lens (510) to reach the surface of the wavelength conversion plate (513). The distance between the second lens and the wavelength conversion plate is controlled by the gasket (512), and the pressing plate (508) fastens the lens, gasket, and wavelength conversion plate to the positioning groove of the reflective body base by screws. Each component cooperates tightly and the optical performance is more stable. The incident angle of the laser beam on the wavelength conversion plate (510) is 0°, the light spot shape on the surface of the wavelength conversion plate is regular and symmetrical, the second lens has a better focusing effect on the emitted white light, and the white light is emitted through the glass window (511) after being focused by the second lens.

[0034] Figure 5 The positioning bosses (601 and 602) used to fix the reflector are as follows: Figure 6 As shown in , the boss is presented as two isosceles right triangles with the horizontal x direction as the reference, the two inclined surfaces form an angle of 45° with the horizontal direction and the right angle sides are parallel, and the reflective sheets can be quickly and effectively fixed on their respective positioning bosses.

[0035] In the present invention, Figure 5 The first reflector is a glass with a length of 6 mm, a width of 2.83 mm, and a thickness of 1.1 mm, and is coated with a total reflection film on one side. The coating structure on the surface of the second reflector is as follows: Figure 7 As shown in FIG. 1 , a 2mm×2.83mm reflective film is coated on one side of a glass having a length of 22mm, a width of 2.83mm, and a thickness of 1.1mm. The reflectivity of the reflective film to blue light (wavelength of 430nm-470nm) is greater than 90%. Figure 8 , using two same Figure 7 Glasses with the same size of the coating and the same size of the non-coating are glued together to form a second reflector.

[0036] Due to the thickness of glass, Figure 4 and Fig. 9 It can be seen that the second reflector formed by gluing two pieces of glass together will block more white light when emitting white light, which directly leads to the second reflector formed by gluing being less efficient than the reflector only partially coated.

[0037] Figure 5 The structure of the medium wavelength conversion plate is as follows Fig.10As shown, it includes a metal substrate (1001), a reflective film (1002), a fluorescent material layer (1003) and an optical anti-reflection film (1004). The incident laser passes through the anti-reflection film (1004) and enters the fluorescent material layer (1002) to interact with it. Part or all of the incident laser is absorbed by the fluorescent material layer and the light of different wavelengths of the conversion layer is output from its outer surface directly through the anti-reflection film (1004), and part passes through the reflective layer (1002) and then reflects out of the anti-reflection film (1004). Generally, the fluorescent material layer is made of a mixture of fluorescent powder and low melting point organic matter, such as silica gel or epoxy resin, and has an obvious disadvantage that it is difficult to withstand high energy density laser irradiation. The present invention uses a fluorescent material layer that does not contain any organic matter, which is directly sintered and combined with the metal substrate below at high temperature, so it can withstand relatively large energy density laser beam irradiation.

[0038] Further, according to Figure 4 We can also use multiple laser diodes to form a laser module array as the light source to excite the wavelength conversion plate to obtain a light source with higher output power. Fig.11 The present invention is a schematic diagram of the structure of a light source for exciting fluorescence by a laser module array, wherein a single laser diode is replaced by a laser module array (1102) composed of multiple laser diodes, so that the input laser light intensity is increased while maintaining the light source efficiency unchanged, thereby increasing the white light intensity and increasing the light emitting area.

[0039] like Fig.11 As shown, the laser module array (1102) is fixed on the laser diode fixing base (1101), and the first lens (1103), the first reflector (1105), the diffuser (1106), the second reflector (1107), the second lens (1108), the gasket (1109), and the wavelength conversion plate (1110) are sequentially placed at the corresponding installation positions of the reflective body base (1104). The installation method and working principle of each component are the same as the light source for exciting fluorescence with a single laser diode.

[0040] It should be understood by those skilled in the art that the embodiments of the present invention described above and shown in the accompanying drawings are only examples and do not limit the present invention. The purpose of the present invention has been fully and effectively achieved. The functions and structural principles of the present invention have been demonstrated and explained in the embodiments. Without departing from the principles, the embodiments of the present invention may be deformed or modified in any way.

Claims

1. A white laser light source, characterized in that: It includes a laser diode module, a first lens, a first reflector, a diffusion sheet, a second reflector, a second lens, a wavelength conversion sheet, a laser diode fixing base, a pressing sheet, a gasket, a reflective body base, a glass window, and a protective cover.

2. A white laser light source according to claim 1, characterized in that: The laser diode module is composed of 1 to 10 laser diodes, and the emission wavelength thereof is between 430 nm and 470 nm.

3. A white laser light source according to claim 1, characterized in that: The first lens is located behind the laser diode module and before the first reflector, has a diameter between 8 mm and 30 mm, and a focal length between 15 mm and 50 mm.

4. A white laser light source according to claim 1, characterized in that: The diffusion sheet is located behind the first reflection sheet and before the second reflection sheet, and has a diffusion angle of 0.5°-10° for laser light and a thickness of 0.3mm-2.0mm.

5. A white laser light source according to claim 1, characterized in that: The first reflection sheet is located behind the first lens and in front of the diffusion sheet, has a thickness between 0.5 mm and 2 mm, and has a reflectivity greater than 90% for blue light with a wavelength of 430 nm to 470 nm.

6. A white laser light source according to claim 1, characterized in that: The second reflective sheet is located behind the diffusion sheet and before the second lens, and has a reflectivity greater than 90% for blue light with a wavelength of 430nm-470nm.

7. The white laser light source according to claim 1, characterized in that: The second reflector has a reflective effect on blue light with a wavelength of 430nm-470nm only in its central area, and the transmittance of the rest of the second reflector to light with a wavelength of 400nm-750nm is greater than 90%. The area of ​​the central area that has a reflective effect on blue light is 0.5mm 2 -9mm 2 between.

8. The white laser light source according to claim 1, characterized in that: The second lens is located behind the second reflective sheet and before the wavelength conversion sheet, has a diameter between 4 mm and 12 mm, and a focal length between 2 mm and 8 mm.

9. The white laser light source according to claim 1, characterized in that: The fluorescent material contained in the wavelength conversion sheet is one or more combinations of the following materials: YAG-Ce-based fluorescent material, LuAG-Ce-based fluorescent material, or oxynitride fluorescent material, which can convert laser light with a wavelength between 430nm and 470nm into fluorescence with a wavelength between 400nm and 700nm.

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