JP2017054785A - Light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light source device having high heat dissipation while restricting the burble of a junction and the destruction of a phosphor layer due to the temperature rise.SOLUTION: A light source device 100 comprises: a light source 1 that radiates excitation light; and a phosphor layer 3 that radiates fluorescence light and the diffused excitation light by receiving the excitation light, and the light source device radiates the fluorescence light and the diffused excitation light as irradiation light. A heat sink 4 is bonded to the phosphor layer 3 to radiate the heat generated in the phosphor layer. On the composition plane of the phosphor layer and the heat sink, a plurality of recesses 6 are formed at least on one of the phosphor layer of the heat sink; and at least part of the recesses is filled with an adhesive 7 so that the phosphor layer and the heat sink are bonded by the adhesive.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a light source device using an excitation light source and a phosphor, and more particularly to a light source device using a laser light emitting element as an excitation light source.

  In light source devices such as automobile headlights in recent years, products using light emitting diodes (LEDs) and laser diodes (LDs) have been proposed and partially put into practical use in order to reduce energy consumption of the light sources. Particularly in the case of an LD light source, the light conversion efficiency is high and the light emitting area is small, which is advantageous for downsizing of the lamp. In a light source device using an LD light source, excitation light (for example, blue laser light) is emitted from a LD element to a phosphor, and light (for example, yellow light) emitted by excitation of the phosphor is mixed with excitation light to produce visible light ( For example, white light) is emitted.

  For example, Patent Document 1 discloses a solid-state light source that emits light having a predetermined wavelength in a wavelength region from ultraviolet light to visible light, and an excitation wavelength from the solid-state light source that is longer than the emission wavelength of the solid-state light source. A phosphor layer including at least one phosphor that emits fluorescence of a wavelength; and a heat dissipation substrate provided on a surface of the phosphor layer opposite to a surface on which the excitation light is incident. The body layer substantially does not contain a resin component, the solid light source and the phosphor layer are arranged spatially separated, and the surface of the phosphor layer on which excitation light is incident is There is described a light source device configured to extract fluorescence using reflection by a reflection surface provided on the opposite side.

JP 2011-129354 A

  In order to increase the luminance of a light source device that combines an LD element and a phosphor, it is necessary to increase the intensity of excitation light that excites the phosphor by increasing the output of the LD element. However, when the excitation light intensity is increased, the calorific value of the phosphor increases, which may cause problems such as a decrease in light emission efficiency due to temperature quenching of the phosphor and deterioration / degradation of materials of the phosphor and peripheral members.

  In this regard, in the light source device described in Patent Document 1, the phosphor layer is made of phosphor ceramic having high thermal conductivity, and this is joined to a heat dissipation substrate to dissipate heat, thereby suppressing the temperature rise of the phosphor layer.

  However, when there is a difference between the thermal expansion coefficient of ceramics and the thermal expansion coefficient of the heat dissipation substrate, peeling of the joints and destruction of the ceramics occur due to changes in the environmental temperature and temperature rise of the phosphor layer during excitation. There is a fear.

  As a method for preventing this, there are a method of interposing a substance having a thermal expansion coefficient between ceramics and a heat sink, and a method of using an elastic substance such as an organic adhesive as a joining member. If used, the heat dissipation is reduced, and it becomes difficult to increase the excitation light intensity.

  Therefore, an object of the present invention is to provide a light source device that suppresses peeling of a bonded portion and destruction of a phosphor layer due to a temperature rise and has high heat dissipation.

  In order to solve the above-described problems, the present invention includes a light source that emits excitation light and a phosphor layer that emits fluorescence and diffused excitation light in response to the excitation light, and the fluorescence and diffused excitation light. Is a light source device that emits light as irradiation light, and includes a heat dissipation plate that is bonded to the phosphor layer and dissipates heat generated in the phosphor layer, and the phosphor layer or A plurality of recesses are formed in at least one of the heat dissipation plates, and at least a part of the recesses is filled with an adhesive, and the phosphor layer and the heat dissipation plate are bonded by the adhesive.

  ADVANTAGE OF THE INVENTION According to this invention, the peeling of the junction part by the temperature rise and the destruction of a fluorescent substance layer can be suppressed, and the light source device which has high heat dissipation can be provided.

1 is a perspective view illustrating a configuration of a light source device in Example 1. FIG. FIG. 3 is a cross-sectional view of a phosphor layer 3 and a heat sink 4 It is a figure which shows an example of arrangement | positioning of the recessed part 6 formed in the fluorescent substance layer. 6 is a cross-sectional view of a phosphor layer 3 and a heat sink 4 in Example 2. FIG. 6 is a diagram illustrating an example of the arrangement of recesses formed in the phosphor layer 3 in Example 3. FIG. It is a figure which shows the modification of arrangement | positioning of the recessed part formed in the fluorescent substance layer. It is a figure which shows the other modification of arrangement | positioning of the recessed part formed in the fluorescent substance layer. 6 is a cross-sectional view of a phosphor layer 3 and a heat sink 4 in Example 4. FIG. It is sectional drawing which shows the modification of the fluorescent substance layer 3 and the heat sink 4. FIG. It is sectional drawing which shows the other modification of the fluorescent substance layer 3 and the heat sink 4. FIG. FIG. 10 is a perspective view illustrating a configuration of a light source device in Example 5. FIG. 4 is a cross-sectional view of the phosphor layer 3 and the light transmissive heat sink 18. It is a figure which shows an example of arrangement | positioning of the recessed part 19 formed in the translucent heat sink.

  Hereinafter, embodiments of a light source device according to the present invention will be described with reference to the drawings.

  In the first embodiment, a configuration of a reflective light source device in which excitation light is incident on a phosphor layer and reflected light is extracted from the phosphor layer will be described.

  FIG. 1 is a perspective view illustrating a configuration of a light source device according to the first embodiment. The light source device 100 includes a semiconductor light emitting element 1, a condenser lens 2, a phosphor layer 3, a heat sink 4, and a reflector (reflector) 5. The semiconductor light-emitting element 1 serving as a light source includes a laser diode (LD), and emits blue laser light as excitation light for the phosphor layer 3. The condenser lens 2 is disposed on the emission side of the semiconductor light emitting element 1 and condenses the excitation light (blue laser light) 20 emitted from the semiconductor light emitting element 1 on the surface of the phosphor layer 3 disposed above. . The phosphor layer 3 receives the excitation light and emits the fluorescence 30 and the diffusely reflected excitation light 20 '.

  The reflector 5 is formed in a curved plate shape that opens obliquely forward and upward, and is disposed so as to face the lower side of the phosphor layer 3. The upper surface of the reflector 5 is a reflection surface 5a that reflects the fluorescence 30 emitted from the phosphor layer 3 and the diffusely reflected excitation light 20 'forward. The reflecting surface 5a is formed in a free-form surface, for example, a shape based on a paraboloid, so as to obtain a desired light distribution. The reflecting surface 5a is disposed so as to face the phosphor layer 3 from the rear side to the lower side of the phosphor layer 3, and the fluorescence 30 emitted from the phosphor layer 3 and the diffusely reflected excitation light 20 ′ are received. , And emitted as irradiation light in front of the apparatus.

FIG. 2 is a cross-sectional view of the phosphor layer 3 and the heat sink 4 in the first embodiment. The phosphor layer 3 is composed of a dispersion medium made of phosphor particles and an inorganic material. The phosphor particles are fluorescent materials that emit fluorescence when excited with blue light. For example, Y ₃ Al ₅ O ₁₂ : Ce, Y ₃ (Al, Ga) ₅ O ₁₂ : Ce, (Y, Gd) ₃ Al _{5 O 12: Ce, (Y,} Lu) 3 Al 5 O 12: Ce, (Ba, Sr) 2 SiO 4: Eu, Ca 3 Sc 2 Si 3 O 12: Ce, (Ca, Sr) 2 Si 5 N 8 : Eu, (Ca, Sr) AlSiN ₃ : Eu, Ca x (Si, Al) ₁₂ (O, N) ₁₆ : Eu, (Si, Al) ₆ (O, N) ₈ : Eu, (Ba, Sr, Ca _{) Si 2 O 2 N 2:} Eu, Ca 8 MgSi 4 O 16 C 12: Eu, SrAl 2 O 4: Eu, Sr 4 Al 14 O 25: Eu, (Ca, Sr) S: Eu, ZnS: Cu, _{Al, CaGa 2 S 4: Eu} , SrGa S _4: Eu or the like can be used.

The dispersion medium is a material that disperses the phosphor particles therein and diffuses the heat of the phosphor particles. For example, Al ₂ O ₃ , MgO, SiO ₂ , TiO ₂ , BaSO ₄ , SrTiO ₄ , Y ₂ O ₃ , La ₂ O ₃ , Y ₃ Al ₅ O ₁₂ , diamond, various transparent glasses, and other materials having transparency to excitation light and fluorescence can be used.

  As a method for forming the phosphor layer 3, for example, a method in which phosphor particles and dispersion medium particles are mixed at a predetermined ratio, pressed into a pellet by a press, and then heated and sintered in a heating furnace. There is. The phosphor layer 3 may be composed of only a phosphor material, and may be a sintered body of phosphor particles or a single crystal of phosphor material.

  In this embodiment, a plurality of recesses 6 are formed on the side of the phosphor layer 3 where the heat sink 4 is bonded, and at least a portion of the recess 6 is filled with an adhesive 7 to dissipate the phosphor layer 3 and the heat sink. The board 4 is bonded. On the bonding surface of the phosphor layer 3, at least a part of the flat portion excluding the recess 6 is in direct contact with the heat sink 4. That is, by directly bringing the phosphor layer 3 and the heat sink 4 into contact, the excitation light 20 enters the phosphor layer 3 and the heat generated when the fluorescence 30 and the diffuse excitation light 20 ′ are emitted from the phosphor layer 3. Can be efficiently transmitted to the heat radiating plate 4 to improve the heat radiation characteristics.

  In the present embodiment, the adhesive force and the heat radiation characteristics change according to the ratio (recess area ratio) of the recess 6 to the joint surface. That is, when the recess area ratio is large, the adhesive force is increased, but the heat dissipation characteristic is decreased. Conversely, when the recess area ratio is small, the heat dissipation characteristic is improved but the adhesive force is decreased. Therefore, the recess area ratio is determined so as to satisfy both the adhesive force and the heat dissipation characteristics. Furthermore, since the reflectivity of the heat radiating plate 4 may change due to the formation of the recesses, and as a result, the luminous efficiency of the phosphor layer 3 may be affected. Therefore, the area ratio of the recesses is determined so as to satisfy these practical characteristics. .

  FIG. 3 is a diagram illustrating an example of the arrangement of the recesses 6 formed in the phosphor layer 3, as viewed from the side of the joint surface with the heat sink 4. The concave portion 6 is formed in a dot shape (hemisphere), and the formation position thereof is determined on the excitation light irradiation surface of the phosphor layer 3 in consideration of the irradiation position of the excitation light and thermal diffusion. First, the size of the phosphor layer 3 (the size in the vertical and horizontal directions in the drawing) is the same as the region 9 (the region serving as a guide for thermal diffusion) in which the thickness value t of the phosphor layer 3 is added to the irradiation range 8 of the excitation light 20. Make it a degree or wider. In this example, it is wider than the region 9. And the formation area of the recessed part 6 is provided so that the excitation light irradiation range 8 may be included in the outer side with the approximate center. Specifically, it is desirable to provide the same size as the region 9 or wider than the region 9. Thereby, a sufficient path for transferring the heat generated in the excitation light irradiation range 8 to the heat radiating plate 4 can be secured. Further, the recess 6 may be formed only outside the range 8 or the region 9.

  Further, at least a part of the recess 6 has a width (dot diameter) w larger than a relative shift amount caused by a difference in thermal expansion coefficient between the phosphor layer 3 and the heat sink 4 when the temperature changes. This is because if the width w of the recess 6 is smaller than the relative displacement amount, the adhesive 7 may be peeled off or cohesively broken due to the displacement between the phosphor layer 3 and the heat sink 4.

  The temperature range assumed here is a temperature range during use and storage of a product to which the light source device 100 of this embodiment is applied. For example, in the case of a vehicle headlight, −40 ° C. to 100 ° C. Is assumed.

  As a method for forming the recess 6, for example, sandblasting, etching, polishing with abrasive grains having a particle size similar to the width of the recess 6, cutting, or laser processing can be used. Or in the formation process of the fluorescent substance layer 3, the method of forming a convex part in the metal mold | die used at the time of a press is also possible. Furthermore, it is desirable to form the flat portion by forming the concave portion 6 by the above forming method and then subjecting the concave portion forming surface to planar polishing. Thereby, the contact area of the fluorescent substance layer 3 and the heat sink 4 can be increased, and a heat dissipation characteristic can be improved.

  The adhesive 7 is a material that can enter the recess 6 in a liquid state at the time of bonding, and has an adhesive force and elasticity that does not cause separation or cohesive failure due to a deviation between the phosphor layer 3 and the heat radiating plate 4 when the temperature changes after curing. Is used. Examples thereof include organic adhesives such as silicone, epoxy and acrylic, low melting point metal bonding materials such as solder and metal brazing material, and low melting point glass.

  In particular, the organic adhesive can be bonded at a relatively low temperature, and is desirable in terms of manufacturing cost and suppression of deterioration of the phosphor material during bonding. Among organic adhesives, an elastic adhesive having an elastic modulus of 100 MPa or less is desirable because it can flexibly absorb the above deviation.

  The adhesive 7 is a material having curing shrinkage, and the amount of curing shrinkage is preferably larger than the amount of thermal expansion at the highest temperature expected to be used. Since the force that always presses the phosphor layer 3 against the heat radiating plate 4 is generated by the shrinkage stress of the adhesive 7, the contact between the phosphor layer 3 and the heat radiating plate 4 can be maintained, and high heat dissipation characteristics can be maintained. it can.

  Further, it is desirable that the adhesive 7 does not contain a solid component such as a filler. If a solid component is included, contact between the phosphor layer 3 and the heat sink 4 may be hindered. Furthermore, it is desirable that the adhesive 7 be a material that is transparent with respect to fluorescence and excitation light of the phosphor. By using a transparent material, absorption of fluorescence and excitation light by the adhesive can be suppressed, and a decrease in light emission efficiency can be suppressed.

  When the adhesive material described above is evaluated from the above viewpoint, a silicone rubber having elasticity and translucency and excellent in environmental resistance is particularly desirable.

  The heat radiating plate 4 has a role of receiving heat generated in the phosphor layer 3 and diffusing and radiating the heat to the outside, and a metal material, an oxide or nitride sintered body, or a single crystal is used. Among these, aluminum as a metal material has a high thermal conductivity and a high reflectance to visible light, and since it can suppress a decrease in luminous efficiency by suppressing the absorption of fluorescence and excitation light by the heat sink, desirable. Moreover, in order to raise the reflectance of the surface of a heat sink, you may coat metal materials, such as silver and zinc. Alternatively, when a nitride such as AlN having a low thermal expansion coefficient and high thermal conductivity is used, the surface thereof may be coated with a metal material such as silver or zinc in order to increase the reflectance.

An example of a method for joining the phosphor layer 3 and the heat sink 4 will be described. Here, an example in which a thermosetting organic adhesive is used as the adhesive 7 will be described.
(1) First, the adhesive 7 is applied to the joint surface of the heat sink 4.
(2) The phosphor layer 3 in which the concave portions 6 are formed in advance is bonded to the joint surface to which the adhesive is applied.
(3) The bonded phosphor layer 3 is pressed against the heat radiating plate 4 to push out an extra adhesive 7 so that the flat portion other than the concave portion 6 of the phosphor layer 3 and the heat radiating plate 4 are brought into direct contact.
(4) Finally, the phosphor layer 3 is put into the heating furnace while being pressed against the heat sink 4 to cure the adhesive 7.
In the step (3), even if a small amount of the adhesive 7 remains between the flat portion of the phosphor layer 3 and the heat radiating plate 4, the thermal conductivity, that is, the heat radiating characteristic is not deteriorated. The

  With the above configuration, the adhesive layer filled with the concave portion suppresses the peeling between the phosphor layer and the heat sink, and further absorbs the stress caused by the difference in thermal expansion coefficient between the phosphor layer and the heat sink, thereby destroying the phosphor layer. Can be suppressed. Since the phosphor layer and the heat radiating plate can be in direct contact with each other at the joint surface other than the recesses, high heat dissipation can be obtained.

  In the light source device described above, the recesses are distributed with the center of the excitation light irradiation range as a substantial center. Further, at least a part of the phosphor layer is in contact with the heat sink inside the region surrounded by the outermost periphery of the region where the recesses are distributed.

  In the light source device described above, the adhesive is an elastic adhesive and has curing shrinkage. The curing shrinkage amount of the adhesive is characterized by being larger than the thermal expansion amount at the maximum temperature assumed during storage and use. As such an adhesive, silicone rubber is preferable.

  In the light source device described above, the bonding surface of the heat radiating plate to the phosphor layer is reflective to the fluorescence emitted from the phosphor layer. As such a heat sink, aluminum is preferable.

  As described above, according to the light source device of Example 1, it is possible to realize a light source device that suppresses peeling of the bonding portion between the phosphor layer and the heat sink and destruction of the phosphor layer due to a temperature rise and has high heat dissipation.

  In addition, although the example which formed the recessed part 6 in the fluorescent substance layer 3 side in the present Example was shown, you may form a recessed part in the heat sink 4 side. Or you may form a recessed part in both the fluorescent substance layer 3 and the heat sink 4. FIG.

  In Example 2, the light source device of Example 1 has a configuration in which an air passage is formed in the phosphor layer 3 to improve the adhesive force between the phosphor layer 3 and the heat sink 4. In addition, about the whole structure of the light source device in Example 2, and the recessed part 6 formed in the fluorescent substance layer 3, it is the same as that of Example 1 (FIGS. 1-3), The overlapping description is abbreviate | omitted.

  FIG. 4 is a cross-sectional view of the phosphor layer 3 and the heat dissipation plate 4 in Example 2, and shows the inside of the phosphor layer 3 in an enlarged manner. The phosphor layer 3 is composed of a sintered body of phosphor particles 10 and dispersion medium particles 11, and has an air passage 12 in which gaps (holes) between the particles are connected to allow air to pass therethrough. .

The phosphor particles 10 are fluorescent materials that emit fluorescence when excited with blue light, and the materials described in Example 1 (for example, Y ₃ Al ₅ O ₁₂ : Ce) are used. The dispersion medium particles 11 are materials that diffuse the heat of the phosphor particles, and the materials described in the first embodiment (for example, Al ₂ O ₃ or the like) are used. The phosphor layer 3 may be composed of only the phosphor particles 10.

  The air passage 12 is in a state where the gaps between the particles are connected and penetrated through the phosphor layer 3, and can be formed by changing the sintering conditions of the phosphor layer 3, and the size and number thereof can be controlled. it can. Specifically, it can be controlled by adjusting the temperature during sintering or the particle diameters of the phosphor particles 10 and the dispersion medium particles 11. As the temperature during sintering is set lower or the particle diameter is set larger, the gaps between the particles increase, and more air passages 12 can be formed.

  The phosphor layer 3 having the air passage 12 and the heat radiating plate 4 are joined in the same manner as in the first embodiment. However, having the air passage 12 has the following effects. By having the air passage 12 inside the phosphor layer 3, the adhesive 7 is discharged while discharging the air inside the recess 6 to the outside via the air passage 12 when the phosphor layer 3 and the heat sink 4 are bonded. Can be filled. As a result, the filling ratio (filling rate) of the adhesive 7 in the recess 6 is improved, and the adhesive force between the phosphor layer 3 and the heat sink 4 is further improved. Furthermore, when a curing shrinkable adhesive is used, the shrinkage stress that presses the phosphor layer 3 against the heat sink 4 increases, and the contact area between the phosphor layer 3 and the heat sink 4 increases, further improving the heat dissipation characteristics. Can be made.

  As described above, according to Example 2, by forming a ventilation path in the phosphor layer, the adhesive force between the phosphor layer and the heat radiating plate can be further improved, and reliability with respect to temperature change and heat radiation characteristics can be improved. it can.

  In this embodiment, a part of the gap formed by controlling the sintering condition of the phosphor layer 3 can be used as the recess 6 used for joining with the heat sink. According to this, the process of forming the recessed part 6 separately by machining etc. can be omitted.

  In Example 3, the shape of the recess formed in the phosphor layer 3 in the light source device of Example 1 is a line-shaped groove, and the adhesive force between the phosphor layer 3 and the heat radiating plate 4 is improved. In addition, the whole structure of the light source device in Example 3, and the structure of the fluorescent substance layer 3 and the heat sink 4 are the same as that of Example 1 (FIG. 1, FIG. 2), and the overlapping description is abbreviate | omitted.

  FIG. 5 is a diagram showing an example of the arrangement of the concave portions formed in the phosphor layer 3 in Example 3, and is a view seen from the side of the joint surface with the heat sink 4. On the bonding surface of the phosphor layer 3, a line-shaped concave portion (concave groove) 13 penetrating the end portion of the bonding surface is formed. The recesses 13 have a lattice pattern, and at least a part of the recesses 13 is filled with the adhesive 7 and bonded to the heat sink 4. At that time, the flat portion excluding the concave portion on the bonding surface of the phosphor layer 3 is brought into direct contact with the heat radiating plate 4 to improve the heat radiation characteristics.

  The formation position of the concave portion (concave groove) 13 (relationship with the excitation light irradiation range 8 and the thermal diffusion region 9) and the width w of the concave portion 13 are the same as the conditions of the concave portion 6 in the first embodiment. In FIG. 5, the shape of the concave portion 13 is a lattice pattern, but it is a line pattern in only one direction, a combination pattern of lines in three or more directions, or a radial pattern with the excitation light irradiation range 8 approximately in the center. There may be.

  As a method for forming the recess 13, for example, there is a method in which polishing is performed only in the penetration direction of the recess by using abrasive grains having the same particle size as the width of the recess. In addition to this, there is a method of forming a convex portion on a mold used at the time of pressing in sandblasting, etching pattern formation, cutting processing, laser processing, and phosphor layer forming step. Furthermore, it is desirable that after forming the recess by the above forming method, the recess forming surface is subjected to planar polishing. Thereby, a contact area with the heat sink 4 can be increased and heat dissipation can be improved.

  The effect of the line-shaped recessed part 13 in Example 3 is demonstrated. By having a recess penetrating at the end of the phosphor layer 3, adhesion is performed while discharging the air inside the recess 6 toward the end of the phosphor layer 3 when the phosphor layer 3 and the heat sink 4 are bonded. Agent 7 can be filled. As a result, the ratio (filling rate) at which the concave portion 13 is filled with the adhesive 7 is improved, and the adhesive strength of the phosphor layer 3 to the heat sink 4 is improved. Further, when a curing shrinkable adhesive is used, the shrinkage stress that presses the phosphor layer 3 against the heat sink increases, and the contact area between the phosphor layer 3 and the heat sink 4 is improved to obtain high heat dissipation. Can do.

Next, a modification of the third embodiment will be described.
FIG. 6 is a view showing a modification of the arrangement of the recesses formed in the phosphor layer 3. The width w of the recess 13 is set to be larger as it is located outward from the center. This is because it is considered that the amount of relative deviation generated at the time of temperature change due to the difference in thermal expansion coefficient between the phosphor layer 3 and the heat radiating plate 4 becomes larger as it is located on the outer side.

  In the case of FIG. 6, since the width of the recess 13 is narrow near the center of the excitation light irradiation range 8 and the contact area between the phosphor layer 3 and the heat radiating plate 4 is wide, high heat dissipation is obtained. On the other hand, since the width of the concave portion 13 is set wide at a position away from the center of the excitation light irradiation range 8, a sufficient adhesive force is ensured.

  Note that the method of changing the width w of the recess 13 according to the position of the joint surface as shown in FIG. 6 can also be applied to the first embodiment. That is, the width (diameter) w of the dot-like recess 6 in FIG. 3 may be enlarged according to the distance from the center of the excitation light irradiation range 8. Furthermore, the concave portion may be formed into a plurality of annular shapes with the excitation light irradiation range 8 as the center, and the width thereof may be enlarged according to the distance from the center.

  FIG. 7 is a view showing another modified example of the arrangement of the concave portions formed in the phosphor layer 3. In the excitation light irradiation range 8, the concave portion (concave groove) 13 formed in the phosphor layer 3 is formed in parallel with the short side direction of the excitation light irradiation range 8. This is to reduce unevenness in light emission from the phosphor layer 3 caused by the recess. This will be described. When the phosphor layer 3 is thin or has a high light transmittance, the light emitted from the light emitting region of the phosphor layer 3 may have unevenness due to the recesses. On the other hand, when the concave portion 13 is formed as shown in FIG. 7, the number of the concave portions with respect to the entire light emitting region is increased, and the light and darkness caused by the concave portion is finely dispersed in the light emitting region, so that it is difficult to be visually recognized as unevenness of the light emission pattern. effective.

  In FIG. 7, in the region outside the excitation light irradiation range 8, the recess 13 is also formed in the direction (lateral direction in the drawing) perpendicular to the short side direction of the excitation light irradiation range 8. You may form only in the direction (drawing longitudinal direction) parallel to the short side direction of the range 8.

  Furthermore, it is desirable to set the direction of the excitation light irradiation range 8 so that the direction of unevenness of the light emission pattern caused by the recess is parallel to the light emission direction of the light source device. This is because if there is unevenness perpendicular to the light emission direction of the light source device, the sense of perspective may be affected by the illusion of the light / dark pattern caused by the unevenness.

  In the light source device described above, the concave portion has a long side parallel to the short side direction of the excitation light irradiation range inside the region facing the excitation light irradiation range. In addition, the concave portions are distributed inside the region facing the excitation light irradiation range so as to be continuous in parallel with the short side direction of the excitation light irradiation range.

  In the light source device described above, the radiation optical system is arranged so that the direction parallel to the light emission direction corresponds to the short side direction of the excitation light irradiation range on the phosphor layer surface in the pattern emitted from the light source device. It is characterized by being.

  In the fourth embodiment, a configuration for reducing the unevenness of the light radiation pattern caused by the recess using a light scattering material or the like will be described. In addition, about the whole structure of the light source device in Example 4, and the recessed part 6 formed in the fluorescent substance layer 3, it is the same as that of Example 1, and the overlapping description is abbreviate | omitted.

  FIG. 8 is a cross-sectional view of the phosphor layer 3 and the heat radiating plate 4 in Example 4, and shows the inside of the recess 6 in an enlarged manner. The light scattering particles 14 are installed inside the recess 6 and the adhesive 7 is filled. Since the light scattering amount is increased by the light scattering particles 14, it is possible to compensate for the light scattering amount that has decreased due to the formation of the recess 6. It is desirable that the light scattering particles 14 installed inside the recess 6 do not protrude from the bonding surface between the phosphor layer 3 and the heat sink 4. This is because when the light diffusion particles 14 protrude, the contact between the phosphor layer 3 and the heat radiating plate 4 is hindered, resulting in a decrease in heat dissipation.

The light scattering particle 14 is a material that diffuses and reflects light emitted from the phosphor, and particles made of the dispersion medium (for example, Al ₂ O ₃ ) described in the first embodiment can be used. Alternatively, when the transmittance of the phosphor layer 3 with respect to the excitation light is high and the excitation light reaches the recess 6, the light scattering particles 14 may contain phosphor particles. Thereby, the excitation light that has not been converted into fluorescence by the phosphor layer 3 can be absorbed and converted into fluorescence.

An example of a method for installing the light scattering particles 14 in the recess 6 will be described.
(1) First, a powder is prepared by mixing the powder of the light diffusing particles 14 and the adhesive 7 before curing.
(2) The prepared paste is applied to the surface of the phosphor layer 3 where the recesses 6 are formed, and the paste is filled in the recesses.
(3) The paste on the bonding surface of the phosphor layer 3 with the heat sink 4 is removed using a squeegee or the like.
(4) After that, the adhesive 7 is applied to the joint surface in the same manner as described in the first embodiment, and the phosphor layer 3 and the heat sink 4 are joined.

  As described above, according to the light source device of the fourth embodiment, it is possible to reduce the unevenness of the light emission pattern due to the concave portion. In addition, although the example which formed the recessed part 6 in the fluorescent substance layer 3 was shown in FIG. 8, you may form a recessed part in the heat sink 4. FIG.

Hereinafter, similarly to FIG. 8, a modified example that reduces unevenness of the light emission pattern caused by the concave portion will be described.
FIG. 9 is a cross-sectional view showing a modification of the phosphor layer 3 and the heat sink 4. A light scattering layer 15 is formed on the bonding surface side of the phosphor layer 3 with the heat radiating plate 4, and the recess 6 is formed in the light scattering layer 15. The depth of the recess 6 is set so as not to penetrate the light scattering layer 15. The light scattering layer 15 scatters and reflects the fluorescence emitted from the excitation light incident surface of the phosphor layer 3, thereby reducing the fluorescence reaching the recess 6 and reducing unevenness of light emitted from the phosphor layer 3. .

  The light scattering layer 15 is made of a material having a thermal expansion coefficient close to that of the material constituting the phosphor layer 3, and has a light scattering property higher than that of the phosphor layer 3 with respect to fluorescence emitted from the phosphor. As the configuration of the light scattering layer 15, for example, a sintered body of particles made of the same material as that of the phosphor layer 3 and a particle size distribution different from that used for the phosphor layer 3 is used. Can be used. Further, a material which is the same base material as the phosphor material used for the phosphor layer 3 and does not include the luminescent center element may be used.

An example of a method for producing the phosphor layer 3 on which the light scattering layer 15 is formed will be described.
(1) First, the material powder constituting the light scattering layer 15 is put into a pressing mold for molding the powder of the phosphor layer 3.
(2) Next, the material powder constituting the portion other than the light scattering layer 15 is charged on the charged powder.
(3) This is compacted by a press machine into pellets, and then heated and sintered in a heating furnace. Thereby, the fluorescent substance layer 3 in which the light-scattering layer 15 was formed can be obtained.

  Although FIG. 9 shows an example in which the concave portion 6 is formed in the light scattering layer 15, the concave portion may be formed in the heat radiating plate 4.

  In the light source device described above, a light scattering layer having a light scattering property with respect to fluorescence emitted from the phosphor layer is provided on the phosphor layer facing the heat dissipation plate, and the light scattering layer is lighter than the phosphor layer. It is characterized by high scattering.

  FIG. 10 is a cross-sectional view showing another modification of the phosphor layer 3 and the heat sink 4. A light transmission layer 16 is formed on the side of the phosphor layer 3 where the heat dissipation plate 4 is bonded, and the recess 6 is formed in the light transmission layer 16. The depth of the recess 6 is set so as not to penetrate the light transmission layer 16. Further, the concave portion 6 is filled with a translucent adhesive 17 having translucency with respect to the fluorescence emitted from the phosphor. By adopting such a configuration, the light transmission layer 16 and the recess 6 transmit the fluorescence to the same extent, so that unevenness of the light radiation pattern caused by the recess 6 can be reduced.

  The light transmission layer 16 is made of a material having a thermal expansion coefficient close to that of the material constituting the phosphor layer 3, and has a light transmittance higher than that of the phosphor layer 3 with respect to the fluorescence emitted from the phosphor. As the configuration of the light transmission layer 16, for example, a sintered body of particles made of the same material as that of the phosphor layer 3 is used, and particles having a small particle size distribution are used so that the denseness is higher than that of the phosphor layer 3. be able to. Alternatively, a material that is the same base material as the phosphor material used for the phosphor layer 3 and that excludes the emission center may be used. Further, a flux that lowers the melting point may be added to improve the denseness.

  As another configuration of the light transmission layer 16, the phosphor layer 3 is a sintered body having voids therein, and the light transmission layer 16 is transparent and has a refractive index higher than that of air and is transparent to fluorescence. It can be set as the structure filled with the material. By filling the gap with the transparent material, it is possible to obtain transparency to fluorescence. The transparent material is a material that is in a liquid state when filled and can enter the void. Examples thereof include organic adhesives such as silicone, epoxy, and acrylic, and low-melting glass.

  The translucent adhesive 17 is a material that can be in a liquid state at the time of joining and can enter the recess 6. After curing, the adhesive strength that does not cause peeling or cohesive failure due to deviation between the phosphor layer 3 and the heat sink 4 when the temperature changes. And a material having elasticity and translucency to excitation light. For example, silicone-based, epoxy-based, acrylic-based organic adhesives, low-melting glass, and the like can be given.

  In particular, the organic adhesive can be bonded at a relatively low temperature, and is desirable in terms of manufacturing cost and suppression of deterioration of the phosphor material during bonding. Among organic adhesives, an elastic adhesive having an elastic modulus of 100 MPa or less, such as silicone rubber, is desirable because it can absorb the above-mentioned displacement flexibly.

  Further, the translucent adhesive 17 is a material having curing shrinkage, and it is desirable that the amount of curing shrinkage is larger than the amount of thermal expansion at the highest temperature assumed to be used. Since the force that always presses the phosphor layer 3 against the heat radiating plate 4 is generated by the shrinkage stress of the translucent adhesive 17, the contact between the phosphor layer 3 and the heat radiating plate 4 can be maintained, and high heat dissipation is maintained. can do.

  Moreover, it is desirable that the translucent adhesive 17 does not contain a solid component such as a filler. This is because if a solid component is included, contact between the phosphor layer 3 and the heat sink 4 may be hindered.

  In view of the above, the translucent adhesive 17 is preferably a silicone rubber having elasticity and translucency and excellent environmental resistance.

  In the above-described light source device, the phosphor layer is provided with a light transmissive layer having light permeability with respect to the fluorescence emitted from the phosphor layer on the side facing the heat dissipation plate, and the light transmissive layer is lighter than the phosphor layer. It is characterized by high permeability.

  In the light source device described above, the adhesive has a light-transmitting property with respect to the fluorescence emitted from the phosphor layer.

  As described above, according to the light source device of Example 4, by providing the light scattering particles, the light scattering layer, or the light transmission layer, it is possible to reduce the unevenness of the light radiation pattern due to the recesses.

  In the fifth embodiment, a configuration of a transmission type light source device in which excitation light is incident from the heat radiation plate side and transmitted light is extracted from the phosphor layer will be described.

  FIG. 11 is a perspective view illustrating the configuration of the light source device according to the fifth embodiment. The same elements as those in the first embodiment (FIG. 1) are denoted by the same reference numerals, and the description thereof will be simply given. The light source device 100 ′ includes a semiconductor light emitting element 1, a condenser lens 2, a phosphor layer 3, a translucent heat radiating plate 18, and a reflector (reflector) 5. The semiconductor light emitting device 1 emits blue laser light as excitation light for the phosphor layer 3. The condensing lens 2 condenses the excitation light 20 emitted from the semiconductor light emitting element 1 on the joint surface between the translucent heat radiating plate 18 and the phosphor layer 3 disposed below. The reflector 5 is disposed so as to face the lower side of the phosphor layer 3, and is configured to reflect the fluorescence 30 emitted from the phosphor layer 3 and the excitation light 20 ′ diffused and transmitted forward by the reflecting surface 5a. ing.

  FIG. 12 is a cross-sectional view of the phosphor layer 3 and the light transmissive heat sink 18 in the fifth embodiment. The translucent heat radiating plate 18 transmits the excitation light 20, receives heat generated in the phosphor layer 3, diffuses and radiates it to the outside, and is composed of a single crystal or glass of a transparent inorganic material. . In particular, sapphire is desirable as a transparent inorganic material because of its high thermal conductivity.

  A plurality of recesses 19 are formed on the joint surface side of the light transmissive heat sink 18. At least a part of the recess 19 is filled with a translucent adhesive 17 to bond the phosphor layer 3 and the translucent heat sink 18. About the constituent material of the translucent adhesive agent 17, since it is the same as what was demonstrated in Example 4 (FIG. 10), description is abbreviate | omitted. At least a part of the planar portion excluding the concave portion 19 on the bonding surface of the light transmissive heat radiating plate 18 is in direct contact with the phosphor layer 3. Since the phosphor layer 3 and the translucent heat radiating plate 18 are in direct contact, the heat of the phosphor layer 3 can be efficiently transmitted to the translucent heat radiating plate 18 to improve the heat radiation characteristics.

  Also in the present embodiment, the adhesive force and the heat dissipation characteristics change according to the ratio (concave area ratio) of the concave portion 19 to the joint surface. Therefore, similarly to Example 1, the recess area ratio is determined so as to satisfy both the adhesive force and the heat dissipation characteristics.

  FIG. 13 is a view showing an example of the arrangement of the recesses 19 formed in the light transmissive heat radiating plate 18, as viewed from the side of the bonding surface with the phosphor layer 3. In this example, the shape of the concave portion 19 is a lattice pattern penetrating the end portion of the bonding surface of the phosphor layer 3. The center of the pattern is formed with the excitation light irradiation range 8 with respect to the phosphor layer 3 substantially as the center. It is desirable that the size of the phosphor layer 3 is approximately the same as or wider than the excitation light irradiation range 8, and the recess 19 is approximately the same as or wider than the range 8. As a result, a sufficient path for radiating the heat generated in the excitation light irradiation range 8 to the translucent heat radiating plate 17 can be secured. Further, the recess 19 is formed only outside the range 8. Thereby, the radiation distribution unevenness which the excitation light which permeate | transmits the fluorescent substance layer 3 and is radiated | emitted to the reflector 5 resulting from the pattern of the recessed part 19 can be suppressed.

  The width w of the concave portion 19 is set wider as it is located outward from the center, as in the third embodiment (FIG. 6). This is because it is considered that the amount of relative deviation generated at the time of temperature change due to the difference in thermal expansion coefficient between the phosphor layer 3 and the translucent heat radiating plate 18 becomes larger as it is located on the outer side.

  Examples of the method of forming the recess 19 include sand blasting, etching pattern formation, cutting, and laser processing. Furthermore, it is desirable that after forming the recess by the above forming method, the recess forming surface is subjected to planar polishing. Thereby, a contact area with the fluorescent substance layer 3 can be increased and heat dissipation can be improved.

  As described above, according to the light source device of Example 5, even in the transmission type light source device, it is possible to suppress the peeling of the joint portion and the destruction of the ceramic due to the temperature change and to obtain high heat dissipation.

  In addition, although the example which formed the recessed part 19 in the translucent heat sink 18 in the present Example was shown, you may form a recessed part in the fluorescent substance layer 3. FIG. Further, in this embodiment, an example in which the concave portions are formed in a lattice shape has been shown. A plurality of annular recesses may be used. Further, in this embodiment, an example in which the concave portion 19 is not formed inside the excitation light irradiation range 8 is shown. However, if the radiation distribution unevenness generated due to the pattern of the concave portion 19 is not a problem in the product, the excitation light A recess 19 may be formed inside the irradiation range 8.

  The present invention is not limited to the embodiments described above, and includes various modifications. The above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, it is possible to add, delete, and replace the configurations of other embodiments with respect to a part of the configurations of the embodiments.

1: Semiconductor light emitting device,
2: Condensing lens,
3: phosphor layer,
4: Heat sink,
5: Reflector,
6: recess,
7: Adhesive,
8: Excitation light irradiation range,
9: Area that is a measure of thermal diffusion,
10: phosphor particles,
11: Dispersion medium particles,
12: Ventilation path
13: recess,
14: Light scattering particles,
15: light scattering layer,
16: light transmission layer,
17: Translucent adhesive,
18: Translucent heat sink,
19: recess,
100: Light source device.

Claims (9)

A light source device that has a light source that emits excitation light and a phosphor layer that emits fluorescence and diffused excitation light in response to the excitation light, and emits the fluorescence and the diffused excitation light as irradiation light There,
A heat sink that dissipates heat generated in the phosphor layer by joining with the phosphor layer,
A plurality of recesses are formed in at least one of the phosphor layer or the heat radiating plate at a joint surface between the phosphor layer and the heat radiating plate, and at least a part of the recess is filled with an adhesive, and the adhesive The phosphor layer and the heat radiating plate are bonded together by the light source device. The light source device according to claim 1,
The phosphor layer and the heat radiating plate are at least partially in contact with each other on the joint surface. The light source device according to claim 1 or 2,
A light source device characterized in that a flat portion parallel to the joint surface is formed in a portion other than the concave portion inside a region surrounded by an outermost periphery of a region where the concave portion is formed. The light source device according to any one of claims 1 to 3,
The size of the phosphor layer is not less than the region obtained by adding the layer thickness value of the phosphor layer to the irradiation range of the excitation light from the light source, and the recess is formed in the range not less than the summed region. A light source device characterized by that. The light source device according to any one of claims 1 to 4,
At least a part of the recess has a width larger than a relative shift amount generated in a temperature range assumed during storage and use due to a difference in thermal expansion coefficient between the phosphor layer and the heat radiating plate. A light source device characterized by the above. The light source device according to claim 5,
The light source device characterized in that the width of the concave portion is formed to be larger as it is located outward from the center of the irradiation range of the excitation light from the light source. The light source device according to any one of claims 1 to 6,
The light source device according to claim 1, wherein the recess is a line-shaped groove penetrating an end portion of the bonding surface of the phosphor layer. The light source device according to any one of claims 1 to 7,
A light source device having an air passage through which air passes inside the phosphor layer. The light source device according to any one of claims 1 to 8,
A light source device characterized in that light scattering particles having light scattering properties with respect to the fluorescence emitted from the phosphor layer are disposed inside the recess.

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