JP2022043713A - Light-emitting device - Google Patents

Abstract

To provide a light-emitting device capable of reducing light leakage from a light-reflecting member.SOLUTION: The light-emitting device includes a laser element, a fluorescent member that converts a wavelength of at least a portion of the light from the laser element, and a light-reflecting member made of ceramics fixed directly or via a translucent bonding member to the side of the fluorescent member. The fluorescent member has a light-extraction surface that is the main surface from which light is extracted. The light-reflecting member has grooves on the surface of the fluorescent member on the side of the light-extraction surface.SELECTED DRAWING: Figure 1

Description

The present invention relates to a light emitting device.

A light emitting device that combines a semiconductor laser element and a fluorescent member is known. Patent Document 1 describes a light emitting device having an excitation light source that emits excitation light and a light emitting unit that receives the excitation light and emits fluorescence. The light emitting device of Patent Document 1 is provided with a structure for defining the light emitting pattern of the light emitting portion, such as forming a reflector around the phosphor layer. The material of the reflector is, for example, a white pigment or ceramics.

Japanese Patent Application Laid-Open No. 2015-002160

However, in a component such as ceramics that reflects light due to the difference in refractive index, a part of the light is incident on the inside of the component. Therefore, in a light emitting device using ceramics as a light reflecting member, light may leak from the surface of the light reflecting member.

The present disclosure includes the following inventions. A light reflecting member composed of a laser element, a fluorescent member that converts at least a part of the light from the laser element into wavelength, and ceramics fixed directly to the side surface of the fluorescent member or via a translucent bonding member. The fluorescent member has a light extraction surface as a main surface from which light from the fluorescent member is taken out, and the light reflecting member has a surface on the side of the light extraction surface of the fluorescent member. A light emitting device provided with a groove in.

According to the light emitting device of the present disclosure, it is possible to reduce the leakage of light from the light reflecting member.

It is a schematic sectional drawing which shows the light emitting device which concerns on embodiment of this invention. 2B is a schematic cross-sectional view taken along the line IIA-IIA of FIG. 2B. It is a schematic top view which shows the fluorescent member and the light reflection member which concerns on embodiment of this invention. It is a table which shows the observation result of Experimental Examples 1-5.

Hereinafter, embodiments of the invention will be described with reference to the drawings as appropriate. However, the method for manufacturing a light emitting device described below is for embodying the technical idea of the present invention, and the present invention is not limited to the following unless otherwise specified. The size and positional relationship of the members shown in each drawing may be exaggerated for the sake of clarity.

FIG. 1 is a schematic cross-sectional view showing a light emitting device 100 according to an embodiment. FIG. 2A is a schematic cross-sectional view taken along the line IIA-IIA of FIG. 2B. FIG. 2B is a schematic top view showing the fluorescent member 12 and the light reflecting member 11 according to the embodiment. The light emitting device 100 of the embodiment includes a laser element 21, a fluorescent member 12, and a light reflecting member 11. The fluorescent member 12 is a member that wavelength-converts at least a part of the light from the laser element 21. The fluorescent member 12 has a light extraction surface 12a which is a main surface from which light from the fluorescent member 12 is taken out. The light reflecting member 11 is made of ceramic and is fixed to the side surface of the fluorescent member 12 directly or via a translucent joining member. The light reflecting member 11 is provided with a groove 11c on the surface (first surface 11a) of the fluorescent member 12 on the side of the light extraction surface 12a.

According to the light emitting device 100, since the groove 11c is provided, the light from the fluorescent member 12 can be reflected by the groove 11c, so that the leakage of light from the first surface 11a of the light reflecting member 11 is reduced. can do. Therefore, it is possible to reduce the leakage of light from the light reflecting member 11.

As shown in FIGS. 2A and 2B, the light reflecting member 11 has a first surface 11a and a second surface 11b on the opposite side of the first surface 11a. The first surface 11a is a surface on the side of the light extraction surface 12a of the fluorescent member 12, and the second surface 11b is a surface on the side of the light incident surface 12b of the fluorescent member 12.

As shown in FIG. 2A, the light reflecting member 11 can have a through hole. Since this through hole serves as a light passage, in this case, the inner wall of the through hole is used as a reflective surface. As the material of the light reflecting member 11, it is preferable to use alumina (Al ₂ O ₃ ) ceramics having high thermal conductivity and high reflectance. The thickness of the light reflecting member 11 is preferably 0.2 mm or more in consideration of the strength. Further, the light reflecting member 11 may be thick enough to hold the fluorescent member 12, and the thickness of the light reflecting member 11 can be 2 mm or less in order to suppress an increase in cost and an increase in the height of the light emitting device 100. ..

In FIG. 2A, the inner wall of the through hole of the light reflecting member 11 has a shape that expands along the traveling direction of light. With such a shape, the return light of the incident light can be reflected by the inner wall of the through hole and efficiently taken out to the light emitting side. Examples of the shape of the opening of the through hole include polygons such as triangles and quadrangles, as well as circular or elliptical shapes. Examples of the shape of the through hole include a columnar shape, a cone shape, or a shape in which these are combined.

A groove 11c is provided on the first surface 11a of the light reflecting member 11. As shown in FIG. 2B, it is preferable that the shape of the inner edge of the groove 11c is the same as the shape of the outer edge of the fluorescent member 12 when viewed from above, that is, when viewed from the side of the light extraction surface 12a of the fluorescent member 12. As a result, it is possible to obtain a light emission pattern having the same shape as the top view of the light extraction surface 12a of the fluorescent member 12. When viewed from the light extraction surface 12a side, the shape of the inner edge of the groove 11c and the shape of the outer edge of the fluorescent member 12 can be circular. Since these shapes are circular, the shape of the light emitting pattern is also circular, which is suitable for combination with a lens. For example, the groove 11c can be provided in a circular shape having the same center as the outer edge of the fluorescent member 12 and having a different diameter. In FIG. 2B, the groove 11c is provided seamlessly over the entire circumference of the fluorescent member 12. As a result, it is possible to reduce light leakage from the first surface 11a of the light reflecting member 11 around the entire circumference of the fluorescent member 12.

As shown in FIG. 2A, the depth d1 of the groove 11c is smaller than the distance d2 from the first surface 11a to the second surface 11b of the light reflecting member 11. The distance d2 from the first surface 11a to the second surface 11b of the light reflecting member 11 can be rephrased as the thickness of the light reflecting member 11. When the thickness of the light reflecting member 11 is not constant as shown in FIG. 2A, the thickness of the portion provided with the groove 11c is defined as the distance d2. The depth d1 of the groove 11c can be within the range of 1/10 or more and 1/3 or less of the distance d2 from the first surface 11a to the second surface 11b of the light reflecting member 11. By setting the value to 1/10 or more, the effect of reducing light leakage due to the groove 11c can be obtained more reliably. By setting the value to 1/3 or less, the possibility of damage to the light reflecting member 11 due to the groove 11c can be reduced. The depth d1 of the groove 11c can be 0.07 mm or more. The depth d1 of the groove 11c may be 0.2 mm or less.

As shown in FIG. 2B, the groove 11c is provided at a position not in contact with the fluorescent member 12 when viewed from the light extraction surface 12a side of the fluorescent member 12. When viewed from the light extraction surface 12a side of the fluorescent member 12, the distance between the groove 11c and the fluorescent member 12 can be 0.07 mm or more, and can be 0.1 mm or less. By setting the distance between the groove 11c and the fluorescent member 12 to 0.1 mm or less, it is possible to more effectively reduce the leakage of light from the light reflecting member 11. When the fluorescent member 12 is fixed to the inner wall of the through hole of the light reflecting member 11, the distance d3 between the groove 11c and the through hole is the groove 11c when viewed from the light extraction surface 12a side of the fluorescent member 12. It may be equal to the distance to the fluorescent member 12. The distance d3 between the groove 11c and the through hole can be 0.07 mm or more, and can be 0.1 mm or less.

The groove 11c is filled with, for example, air. In this case, the light inside the light reflecting member can be reflected in the groove 11c due to the difference in refractive index between the air and the light reflecting member 11. In top view, the width of the groove 11c can be, for example, 15 μm or more, and 40 μm or less. In FIG. 2A, the inner wall of the groove 11c is inclined so that the inner diameter of the groove 11c expands from the second surface 11b toward the first surface 11a. Since the inner wall of the groove 11c has such a shape, it is easy to reflect light in the groove 11c in the direction toward the second surface 11b. Therefore, it is possible to further reduce the light leakage from the first surface 11a of the light reflecting member 11. The groove 11c can be formed, for example, by laser processing by laser irradiation.

The light reflecting member 11 is fixed to the side surface of the fluorescent member 12 directly or via a translucent joining member. Examples of the translucent joining member include glass such as borosilicate glass, soda-lime glass, soda glass, and lead glass. For example, borosilicate glass having a softening point between 500 ° C. and 900 ° C. can be used as a translucent bonding member. In FIGS. 2A and 2B, the light reflecting member 11 is provided with a through hole, and the fluorescent member 12 is fixed to the inner wall of the through hole.

The fluorescent member 12 contains a phosphor that emits fluorescence by excitation light. The excitation light is light emitted by the laser element 21. Examples of the phosphor include cerium-activated yttrium aluminum garnet (YAG), cerium-activated lutetium aluminum garnet (LAG), europium and / or chromium-activated nitrogen-containing calcium aluminosilicate (. Examples thereof include CaO-Al ₂ O ₃ -SiO ₂ ), europium-activated silicate ((Sr, Ba) ₂ SiO ₄ ), α-sialon phosphor, β-sialon phosphor and the like. As the fluorescent substance, it is preferable to use a YAG fluorescent substance, which is a fluorescent substance having good heat resistance.

As shown in FIG. 2A, the fluorescent member 12 can be arranged in the through hole of the light reflecting member 11. The fluorescent member 12 has a light extraction surface 12a and a light incident surface 12b. The fluorescent member 12 can further have a side surface connecting the light extraction surface 12a and the light incident surface 12b. As shown in FIG. 2A, the side surface has a shape that substantially matches the inner wall of the through hole to improve the adhesion to the light reflecting member 11 and effectively dissipate the heat generated by the fluorescent member 12 to the light reflecting member 11. Can escape to the side.

Examples of the fluorescent member 12 include ceramics containing a fluorescent substance or a single crystal of the fluorescent substance. Since the fluorescent member 12 is made of such a material having good light resistance and heat resistance, deterioration is unlikely to occur even when irradiated with high-density light such as laser light. The thickness of the fluorescent member 12 is, for example, about 0.1 mm to 1.5 mm. The fluorescent member 12 can be, for example, a fluorescent ceramic in which a fluorescent material and a translucent material such as aluminum oxide (Al ₂ O ₃ , melting point: about 1900 ° C to 2100 ° C) are sintered. In this case, the content of the phosphor is preferably 0.05 to 50% by weight, more preferably 1 to 30% by weight, based on the total weight of the fluorescent member 12. Further, the fluorescent ceramics formed by sintering the powder of the phosphor without using such a translucent material may be used as the fluorescent member 12. Further, as the fluorescent member 12, a single crystal made of a fluorescent substance may be used. The surface of the fluorescent member 12 may be coated with a bandpass filter or the like. The fluorescent member 12 may be composed of a single layer or may be composed of two or more layers.

The laser element 21 is arranged so that the emitted laser light is applied to the light incident surface 12b of the fluorescent member 12. The laser element 21 is, for example, a semiconductor laser element. A translucent member that does not contain a phosphor such as sapphire may be arranged on the light incident surface 12b side of the fluorescent member 12. In this case, the light from the laser element 21 irradiates the fluorescent member 12 via the translucent member.

As shown in FIG. 1, the light emitting device 100 has a package having a laser element 21. The light reflecting member 11 is sandwiched and fixed between the holding portion 15 and the lid portion 16. The light reflecting member 11 has a through hole, and the fluorescent member 12 is arranged in the through hole. As shown in FIG. 1, the lid portion 16 has a first lid portion 16A arranged on the second surface 11b which is the lower surface of the light reflecting member 11 and a second lid portion connected to the lower surface of the first lid portion 16A. It may consist of two parts with 16B.

As shown in FIG. 1, the package includes a stem 24, a lead terminal 25 penetrating the stem 24, a submount 26 fixed to the side surface of a convex portion of the stem 24, and a laser element fixed to the submount 26. Has 21. The package further has a cap 22 fixed to the stem 24 and a lens 23 fixed to the opening of the cap 22. The lid portion 16 is fixed to the stem 24. As shown by the alternate long and short dash line in FIG. 1, the laser light emitted from the laser element 21 is focused by the lens 23, focused in front of the fluorescent member 12, and incident on the fluorescent member 12. When the light emitted by the light emitting device 100 is white light, for example, the fluorescence emitted by the fluorescent member 12 is yellow light, and the laser light emitted by the laser element 21 is blue light (peak wavelength is about 420 nm to 470 nm). Examples of the fluorescent substance contained in the fluorescent member 12 include a yellow fluorescent substance such as a YAG fluorescent substance. Examples of the laser element 21 that emits blue laser light include a GaN-based laser element having an active layer of an InGaN well layer. The package may have wires that electrically connect the laser element 21 and each of the lead terminals 25.

(Experimental example)
As Experimental Examples 1 to 5, the fluorescent member 12 and the light reflecting member 11 shown in FIGS. 2A and 2B were produced. In Experimental Examples 1 to 5, the thickness of the light reflecting member 11 was 0.67 mm. In Experimental Examples 1 to 5, the top view shape of the light reflecting member 11 was a circle with a diameter of 4 mm, and the top view shape of the fluorescent member 12 was a circle with a diameter of 0.65 mm. The groove 11c is provided in a circular shape having the same center as the outer edge of the fluorescent member 12 and having a different diameter. Regarding the grooves 11c, Experimental Examples 1 to 3 were formed by laser machining at a position having a diameter of 0.8 mm, and Experimental Examples 4 and 5 were formed by laser machining at a position having a diameter of 1.2 mm. The distance between the groove 11c and the fluorescent member 12 in the top view was about 0.07 mm in Experimental Examples 1 to 3 and about 0.27 mm in Experimental Examples 4 and 5. The depth of the groove 11c was 0.07 mm for Experimental Example 1, 0.14 mm for Experimental Example 2, 0.2 mm for Experimental Example 3, 0.14 mm for Experimental Example 4, and 0.2 mm for Experimental Example 5. The light incident surface 12b of the fluorescent members 12 of Experimental Examples 1 to 5 was irradiated with excitation light and observed from the light extraction surface 12a side. The results are shown in FIG.

From FIG. 3, it can be said that the shorter the distance between the groove 11c and the fluorescent member 12, and the larger the depth of the groove 11c, the more the light leakage from the surface of the light reflecting member 11 can be reduced.

11 Light reflecting member 11a First surface 11b Second surface 11c Groove 12 Fluorescent member 12a Light extraction surface 12b Light incident surface 15 Holding part 16 Cover part 16A First lid part 16B Second lid part 21 Laser element 22 Cap 23 Lens 24 Stem 25 Lead terminal 26 Submount 100 Light emitting device

Claims (7)

Laser element and
A fluorescent member that converts at least a part of the light from the laser element into wavelength,
A light-reflecting member made of ceramics fixed directly to the side surface of the fluorescent member or via a translucent bonding member, and a light-reflecting member.
Equipped with
The fluorescent member has a light extraction surface which is a main surface from which light from the fluorescent member is taken out.
The light reflecting member is a light emitting device having a groove on the surface of the fluorescent member on the side of the light extraction surface. The light emitting device according to claim 1, wherein the shape of the inner edge of the groove is the same as the shape of the outer edge of the fluorescent member when viewed from the side of the light extraction surface. The light emitting device according to claim 2, wherein the shape of the inner edge of the groove and the shape of the outer edge of the fluorescent member are circular when viewed from the side of the light extraction surface. The light reflecting member has a first surface provided with the groove and a second surface on the side opposite to the first surface.
The one according to any one of claims 1 to 3, wherein the depth of the groove is within the range of 1/10 or more and 1/3 or less of the distance from the first surface to the second surface of the light reflecting member. Light emitting device. The light reflecting member is provided with a through hole and has a through hole.
The light emitting device according to any one of claims 1 to 4, wherein the fluorescent member is fixed to the inner wall of the through hole. The light emitting device according to claim 5, wherein the distance between the groove and the through hole is within a range of 0.07 mm or more and 0.1 mm or less when viewed from the side of the light extraction surface. The light emitting device according to any one of claims 1 to 6, wherein the groove is filled with air.

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