JP2012123941A - Light-emitting device, vehicular headlight, and lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting device capable of restraining deterioration of a light-emitting section and reduction in the light-emitting efficiency of a light-emitting section.SOLUTION: The headlight (light-emitting device) 1 includes: a plurality of laser elements 2 having active layers 111 for emitting laser beams; and the light-emitting section 4 having a light receiving surface 4a for receiving the laser beams emitted from the laser elements 2 and emitting light by receiving the laser beams on the light receiving surface 4a. Intersection lines 33 made by first planes 31 including the active layers 111 and a second plane 32 including the light receiving surface 4a are not completely overlapped by each other.

Description

  The present invention relates to a light-emitting device, a vehicle headlamp, and an illumination device that use fluorescence generated by irradiating a phosphor with excitation light as illumination light.

  In recent years, semiconductor light emitting devices such as light emitting diodes (LEDs) and semiconductor lasers (LDs) are used as excitation light sources, and excitation light generated from these excitation light sources is emitted to light emitting units including phosphors. Research on light-emitting devices that use fluorescence generated by the above as illumination light has become active.

  An example of such a light emitting device is a vehicular lamp disclosed in Patent Document 1. A phosphor and a semiconductor light emitting element that irradiates the phosphor with excitation light from a plurality of different directions are provided. When the semiconductor light emitting element irradiates the phosphor with light, the phosphor can generate fluorescence (white light).

JP 2004-241142 A (published August 26, 2004)

  By irradiating the excitation light, an irradiation region (beam spot) is formed on the surface of the light emitting unit including the phosphor. However, since the light emitting unit is irradiated with the excitation light from a plurality of directions, a large number of irradiation regions are also formed. For this reason, when excitation light from a plurality of directions is locally irradiated on the surface of the light emitting portion, a large number of irradiation regions are overlapped to generate heat, and the portion is exposed to a high temperature.

  Due to this heat generation, there is a possibility that the light emission efficiency of the light emitting part is lowered, and the phosphor forming the light emitting part and the sealing material for sealing the phosphor may be deteriorated. When the phosphor or the sealing material is deteriorated (that is, when a part of the light emitting part is deteriorated), the inventor of the present invention decreases the luminous efficiency of the deteriorated phosphor, and as a result, the light emitting part as a whole. It has been confirmed by experiments that there is a possibility that the light emission efficiency of the light source will be lowered.

  However, Patent Document 1 does not disclose or suggest such a configuration for suppressing the deterioration of the light emitting unit and the decrease in the light emission efficiency of the light emitting unit.

  The objective of this invention is providing the light-emitting device, the vehicle headlamp, and the illuminating device which can suppress degradation of a light-emitting part, and the fall of the light emission efficiency in a light-emitting part.

  In order to solve the above problems, a light emitting device according to the present invention has a plurality of excitation light sources having an emission layer that emits excitation light, and a light receiving surface that receives excitation light emitted from the excitation light source, A light emitting section that emits light upon receiving the excitation light on the light receiving surface, and the intersecting lines formed by the first plane including the emission layer and the second plane including the light receiving surface do not completely overlap each other. It is characterized by.

  According to the said structure, the excitation light radiate | emitted from the output layer which each of several excitation light sources has is irradiated to the light-receiving surface of a light emission part. That is, the excitation light source and the light emitting part are arranged so that the part of the emission layer of the excitation light source that emits excitation light faces the light receiving surface of the light emitting part. For this reason, the intersection line which the 1st plane containing an output layer and the 2nd plane containing a light-receiving surface make can be formed for every excitation light source.

  Further, due to the arrangement of the excitation light source and the light emitting unit, the intersection line is included in the irradiation region formed when the light receiving surface is irradiated with the excitation light. For this reason, the situation that the intersecting lines are completely overlapped means that the overlapping portion of the irradiation regions formed by the excitation light emitted from the individual excitation light sources is large. Even if the excitation light from one excitation light source generates heat in the irradiation region, if the irradiation regions formed by the excitation light from multiple excitation light sources overlap, the amount of heat generated in the overlapping portion increases. The light emitting part may be deteriorated by the heat.

  In the light emitting device of the present invention, since the intersecting lines do not completely overlap, the overlapping portion between the irradiation regions formed by the excitation light emitted from the plurality of excitation light sources can be reduced. For this reason, the heat generation of the light emitting part can be suppressed by preventing the excitation light from being locally irradiated to one place of the light emitting part. Therefore, in the light emitting device of the present invention, it is possible to suppress the deterioration of the light emitting part and the decrease in the light emission efficiency in the light emitting part due to the heat generation.

  In order to solve the above problems, a light emitting device according to the present invention has a plurality of excitation light sources having an emission layer that emits excitation light, and a light receiving surface that receives excitation light emitted from the excitation light source, A light emitting portion that emits light upon receiving excitation light on the light receiving surface, and two intersections selected from the intersection lines formed by each of the first plane including the emission layer and the second plane including the light receiving surface. It is characterized in that the lines intersect at an angle larger than 0 ° and smaller than 180 °.

  According to the said structure, the excitation light radiate | emitted from the output layer which each of several excitation light sources has is irradiated to the light-receiving surface of a light emission part. As described above, an intersection line formed by the first plane including the emission layer and the second plane including the light receiving surface can be formed for each excitation light source because of the arrangement relationship between the excitation light source and the light emitting unit.

  Further, due to the arrangement of the excitation light source and the light emitting unit, the intersection line is included in the irradiation region formed when the light receiving surface is irradiated with the excitation light. For this reason, the situation where two intersecting lines selected from a plurality of intersecting lines intersect at an angle of 0 ° or 180 ° (that is, the intersecting lines completely overlap) is emitted from the two excitation light sources. This means that the overlapping part of the irradiation areas formed by the excited light is increased.

  In the light emitting device of the present invention, the two intersecting lines intersect each other at an angle larger than 0 ° and smaller than 180 °, so that an overlapping portion of irradiation areas formed by excitation light emitted from a plurality of excitation light sources is formed. Can be small. For this reason, the heat generation of the light emitting part can be suppressed by preventing the excitation light from being locally irradiated to one place of the light emitting part. Therefore, in the light emitting device of the present invention, it is possible to suppress the deterioration of the light emitting part and the decrease in the light emission efficiency in the light emitting part due to the heat generation.

  Further, in the light emitting device according to the present invention, when the angle formed by the intersecting lines formed by two adjacent excitation light sources is θ, the excitation light source satisfies θ = 180 ° / the number of excitation light sources. Preferably they are arranged.

  In the case where the angle formed by the intersecting lines formed by two adjacent excitation light sources is not constant, a portion (for example, the region 41 in FIG. 9B) where the irradiation regions overlap closely on the light receiving surface of the light emitting unit. A sparse overlapping portion (for example, the region 42 in FIG. 9B) is formed. In the dense overlapping portion, the amount of heat generation is large, and therefore, it is more likely to deteriorate than in other regions.

  According to the above configuration, since the excitation light source and the light emitting unit are arranged so that the angle formed by the intersecting lines is constant, that is, the intersecting lines are formed uniformly, the irradiation formed by the excitation light emitted from each of the excitation light sources The region is formed uniformly on the light receiving surface. For this reason, it is possible to eliminate a portion where the irradiation regions overlap closely, and thus it is possible to suppress deterioration of the light emitting portion due to local heat generation.

  The light-emitting device according to the present invention includes a biconvex lens that adjusts a range of an irradiation region on the light-receiving surface, the excitation light source is disposed at one focal position of the biconvex lens, and the light-emitting unit includes the both light-emitting units. It is preferable that the second lens is located on the other focal position side of the convex lens and at a position where the length of the major axis of the irradiation region substantially coincides with the distance between the two most distant points on the outer periphery of the light receiving surface.

  According to the above configuration, since the biconvex lens is provided, the light receiving surface can be appropriately irradiated with the excitation light emitted from the excitation light source.

  In addition, since the excitation light source is arranged at one of the two focal positions of the biconvex lens, the light intensity distribution of the excitation light emitted from the excitation light source is not dispersed, and the magnitude of the light intensity is reduced. While maintaining (for example, maintaining the Gaussian distribution), the light emitting unit can be irradiated with excitation light. For this reason, the luminous efficiency in the light emission part per one excitation light source can be improved.

  In addition, since the light emitting unit is arranged at the other focal position side of the two focal positions and at the position where the two lengths substantially coincide with each other, the excitation light is applied only to a region smaller than the size of the light receiving surface. Can be prevented, and excitation light can be prevented from being irradiated to areas other than the light emitting portion. For this reason, the fall of the excitation efficiency of a light emission part and the irradiation efficiency with respect to the light-receiving surface of excitation light can be prevented.

  In the light emitting device according to the present invention, it is preferable that the light intensity distribution of the excitation light on the light receiving surface is more dispersed than the Gaussian distribution.

  According to the above configuration, since the light intensity distribution of the excitation light is more dispersed than the Gaussian distribution, the maximum light density of the excitation light is smaller than the maximum light density in the case of the Gaussian distribution. For this reason, the heat_generation | fever in the light-receiving surface by excitation light can be suppressed for every excitation light source. Therefore, the heat generation of the entire light emitting unit can be further suppressed.

  In addition, the light emitting device according to the present invention includes a biconvex lens that adjusts a range of an irradiation region on the light receiving surface, and a distance between the excitation light source and the biconvex lens is shorter than a focal length of the biconvex lens. The excitation light source or the biconvex lens is preferably arranged.

  According to the above configuration, the light intensity distribution of the excitation light on the light receiving surface can be dispersed more than the Gaussian distribution (see, for example, FIG. 15B).

  In the light emitting device according to the present invention, it is preferable that a plurality of peaks are formed in the light intensity distribution of the excitation light on the light receiving surface.

  According to the above configuration, a plurality of peaks are formed in the light intensity distribution of the excitation light on the light receiving surface, so that the light intensity distribution can be dispersed more than the Gaussian distribution (see, for example, FIG. 19B).

  Further, the light emitting device according to the present invention includes a biconvex lens that adjusts a range of an irradiation region on the light receiving surface, and a distance between the excitation light source and the biconvex lens is longer than a focal length of the biconvex lens. The excitation light source or the biconvex lens is preferably arranged.

  According to the above configuration, in the light intensity distribution of the excitation light on the light receiving surface, a plurality of peaks that are more dispersed than the Gaussian distribution can be formed.

  In the light emitting device according to the present invention, it is preferable that the length of the long axis of the irradiation region on the light receiving surface is substantially the same as the length between the two most distant points on the outer periphery of the light receiving surface.

  According to the above configuration, since the two lengths are substantially the same, the excitation light is irradiated only to a region smaller than the size of the light receiving surface, or the excitation light is irradiated to a region other than the light emitting portion. Can be prevented. For this reason, the fall of the excitation efficiency of a light emission part and the irradiation efficiency with respect to the light-receiving surface of excitation light can be prevented.

  Moreover, the vehicle headlamp and the lighting device according to the present invention include the light-emitting device described above. For this reason, similarly to said light-emitting device, the vehicle headlamp and the illuminating device which can suppress deterioration of a light emission part and the fall of the light emission efficiency in a light emission part are realizable.

  As described above, the light-emitting device according to the present invention has a plurality of excitation light sources having an emission layer that emits excitation light, and a light-receiving surface that receives excitation light emitted from the excitation light source. And a light emitting portion that emits light upon receiving the excitation light, and the intersecting line formed by the first plane including the emission layer and the second plane including the light receiving surface does not completely overlap.

  Therefore, there is an effect that it is possible to suppress deterioration of the light emitting unit and a decrease in light emission efficiency in the light emitting unit.

It is a figure which shows the mode of the irradiation area | region formed in a light-receiving surface when a laser beam is radiate | emitted from the laser element of the headlamp which concerns on one Embodiment of this invention. It is a figure which shows schematic structure of the headlamp which concerns on one Embodiment of this invention, (a) is the top view, (b) is the sectional drawing. It is a figure for demonstrating the basic structure of a laser element, (a) shows typically the circuit diagram of a laser element, (b) is a perspective view which shows the basic structure of a laser element. It is a figure which shows the positional relationship of a laser element, a lens, and a light emission part. It is a conceptual diagram showing the paraboloid of the parabolic mirror, (A) is a top view of a parabolic mirror, (b) is a front view, and (c) is a side view. It is a figure which shows an example of a mode that a laser beam is radiate | emitted from a laser element, (a) is the x-axis by which the intersection line which the reference plane provided for every laser element and a 1st plane make was provided in the reference plane (B) shows the case where the line of intersection between the reference plane and the first plane has an inclination. It is a figure which shows the irradiation area | region which the laser beam radiate | emitted from one laser element forms in a light-receiving surface, and its light intensity distribution. An example of the position of the intersection line on the reference plane when three laser elements are arranged, and an example of the position of the intersection line on the second plane and the position of the irradiation area are shown. (A) intersects the axis on the reference plane. The angle formed with each line is shown, and (b) shows the positions of the intersection line and the irradiation area formed on the second plane. It shows another example of a top view of a headlamp according to an embodiment of the present invention. An example of the position of the intersection line on the reference plane when four laser elements are arranged, and an example of the position of the intersection line on the second plane and the position of the irradiation region are shown. (A) intersects with the axis on the reference plane. The angle formed with each line is shown, and (b) shows the positions of the intersection line and the irradiation area formed on the second plane. It is a schematic diagram of a biconvex lens. FIG. 2 shows an example of a positional relationship among a laser element, a lens, and a light emitting unit included in a headlamp according to an embodiment of the present invention, and FIG. 4A shows a case where the light emitting unit is arranged at a position shorter than the focal length of the lens. (B) shows the case where the light emitting part is arranged at a position longer than the focal length of the lens. It is sectional drawing which shows the structure of the headlamp which concerns on other embodiment of this invention. It is a figure which shows the irradiation area | region which the laser beam radiate | emitted from one laser element forms in a light-receiving surface, and its light intensity distribution, (a) is a case where a laser element is arrange | positioned in a focus position, (b) Indicates a case where the laser element is displaced from the focal position. It shows an example of a positional relationship between a laser element, a lens, and a light emitting unit provided in a headlamp according to another embodiment of the present invention, and (a) shows a case where the light emitting unit is arranged at a position shorter than the focal length of the lens. (B) shows the case where the light emitting part is arranged at a position longer than the focal length of the lens. It is a figure which shows the position of each intersection line and irradiation area | region formed in a 2nd plane when a laser element and a lens are arrange | positioned at the headlamp which concerns on other embodiment of this invention. It is sectional drawing which shows the structure of the headlamp which concerns on further another embodiment of this invention. It is a figure which shows the irradiation area | region which the laser beam radiate | emitted from one laser element forms in a light-receiving surface, and its light intensity distribution, (a) is a case where a laser element is arrange | positioned in a focus position, (b) Indicates a case where the laser element is displaced from the focal position. It is a figure which shows the irradiation area | region which the laser beam radiate | emitted from one laser element forms in a light-receiving surface, and its light intensity distribution, and shows the case where an irradiation area | region is irradiated also to areas other than a light-receiving surface . The position of the intersection line and irradiation area formed on the second plane when a laser element and a lens are arranged in a headlamp according to still another embodiment of the present invention is shown. It is a conceptual diagram which shows the arrangement | positioning direction of a headlamp.

Embodiment 1
The following describes one embodiment of the present invention with reference to FIGS.

<Configuration of headlamp 1>
2A and 2B are diagrams showing a schematic configuration of a headlamp 1 according to an embodiment of the present invention, wherein FIG. 2A is a top view and FIG. 2B is a cross-sectional view thereof. As shown in FIG. 2B, the headlamp 1 includes a laser element (excitation light source, semiconductor laser) 2, a lens 3, a light emitting unit 4, a parabolic mirror (reflecting mirror) 5, a metal base (thermal conductive member, support). Member) 7 and a fin (cooling part) 8.

(Laser element 2)
The laser element 2 is a light emitting element that functions as an excitation light source that emits excitation light. A plurality of laser elements 2 are provided, and laser light as excitation light is oscillated from each of the plurality of laser elements 2. In the present embodiment, when there are a plurality of laser elements 2, for convenience, reference numerals 2a, 2b, 2c,...

  The laser element 2 may have one light emitting point on one chip, or may have a plurality of light emitting points on one chip. When one chip has a plurality of light emitting points, the direction of the active layer 111 of the laser element 2 in the chip is preferably the same. The direction of the active layer 111 (axial direction perpendicular to the optical axis L of the laser beam on the first plane 31) will be described later with reference to FIG. The basic structure of the laser element 2 including the active layer 111 will be described later with reference to FIG.

  The wavelength of the laser beam of the laser element 2 is, for example, 405 nm (blue purple) or 445 nm (blue), but is not limited thereto, and may be appropriately selected according to the type of phosphor included in the light emitting unit 4. .

  Moreover, it is also possible to use a light emitting diode (LED) instead of a laser element as an excitation light source (light emitting element).

(Structure of laser element 2)
Here, the basic structure of the laser element 2 will be described. 3A and 3B are diagrams for explaining the basic structure of the laser element 2. FIG. 3A schematically shows a circuit diagram of the laser element 2, and FIG. 3B shows the basic structure of the laser element 2. FIG. It is a perspective view. As shown in the figure, the laser element 2 has a configuration in which a cathode electrode 19, a substrate 18, a clad layer 113, an active layer 111 (emission layer), a clad layer 112, and an anode electrode 17 are laminated in this order.

The substrate 18 is a semiconductor substrate, and it is preferable to use GaN, sapphire, or SiC in order to obtain blue to ultraviolet excitation light for exciting the phosphor as in the present application. In general, as other examples of the substrate for the laser element, III-IV represented by group IV semiconductors such as Si, Ge and SiC, GaAs, GaP, InP, AlAs, GaN, InN, InSb, GaSb and AlN. Group V compound semiconductors, Group II-VI compound semiconductors such as ZnTe, ZeSe, ZnS and ZnO, oxide insulators such as ZnO, Al ₂ O ₃ , SiO ₂ , TiO ₂ , CrO ₂ and CeO ₂ , and SiN Any material of the nitride insulator is used.

  The anode electrode 17 is for injecting current into the active layer 111 through the cladding layer 112.

  The cathode electrode 19 is for injecting current into the active layer 111 from the lower part of the substrate 18 through the clad layer 113. The current is injected by applying a forward bias to the anode electrode 17 and the cathode electrode 19.

  The active layer 111 has a structure sandwiched between the clad layer 113 and the clad layer 112. In other words, the laser element 2 has a configuration including the active layer 111 that emits laser light.

  As the material for the active layer 111 and the cladding layer, a mixed crystal semiconductor made of AlInGaN is used to obtain blue to ultraviolet excitation light. In general, a mixed crystal semiconductor mainly composed of Al, Ga, In, As, PN, and Sb is used as an active layer / cladding layer of a laser element, and such a configuration may be used. Moreover, you may be comprised by II-VI group compound semiconductors, such as Zn, Mg, S, Se, Te, and ZnO.

  The active layer 111 is a region where light emission is caused by the injected current, and the emitted light is confined in the active layer 111 due to a difference in refractive index between the cladding layer 112 and the cladding layer 113.

  Further, the active layer 111 is formed with a front side cleaved surface 114 and a back side cleaved surface 115 provided to face each other in order to confine light amplified by stimulated emission, and the front side cleaved surface 114 and the back side cleaved surface 115. Plays the role of a mirror.

  However, unlike a mirror that completely reflects light, a part of the light amplified by stimulated emission is obtained by cleaving the front side cleaved surface 114 and the back side cleaved surface 115 of the active layer 111 (in this embodiment, the front side cleaved surface 114 for convenience. And the excitation light L0. Note that the active layer 111 may form a multilayer quantum well structure.

  Note that a reflective film (not shown) for laser oscillation is formed on the back side cleaved surface 115 opposite to the front side cleaved surface 114, and the difference in reflectance between the front side cleaved surface 114 and the back side cleaved surface 115 is different. By providing, for example, most of the excitation light L0 can be emitted from the light emitting point 103 from the front-side cleavage surface 114 which is a low reflectance end face.

  The clad layer 113 and the clad layer 112 are made of n-type and p-type GaAs, GaP, InP, AlAs, GaN, InN, InSb, GaSb, and AlN group III-V compound semiconductors, and ZnTe, ZeSe. , ZnS, ZnO, and other II-VI group compound semiconductors, and by applying a forward bias to the anode electrode 17 and the cathode electrode 19, current can be injected into the active layer 111. It has become.

  As for film formation with each semiconductor layer such as the clad layer 113, the clad layer 112, and the active layer 111, MOCVD (metal organic chemical vapor deposition) method, MBE (molecular beam epitaxy) method, CVD (chemical vapor deposition) method. The film can be formed using a general film forming method such as a laser ablation method or a sputtering method. The film formation of each metal layer can be configured using a general film forming method such as a vacuum deposition method, a plating method, a laser ablation method, or a sputtering method.

(Light emission principle of the light emitting unit 4)
Next, the light emission principle of the phosphor by the laser light oscillated from the laser element 2 will be described.

  First, the laser light oscillated from the laser element 2 is irradiated onto the phosphor included in the light emitting unit 4, whereby electrons existing in the phosphor are excited from a low energy state to a high energy state (excited state).

  After that, the electrons in the high energy state are partially deprived of energy due to collisions between molecules to cause a vibrational transition, and finally transition from an excited state to a low energy state (ground state).

  As described above, the phosphor excited by the high energy state and causing the vibrational transition makes a transition to the low energy state, whereby the phosphor emits light.

  White light can be composed of a mixture of three colors that satisfy the principle of equal color, or a mixture of two colors that satisfy the relationship of complementary colors. Based on this principle and relationship, the color of the laser light oscillated from the laser element 2 White light can be generated in combination with the color of light emitted from the phosphor.

(Lens 3)
The lens 3 is irradiated with a laser beam irradiation region 34 (laser beam spot or excitation spot) so that the light emitting unit 4 is appropriately irradiated with the laser beam emitted from the laser element 2 (see FIG. 9B). Is a lens for adjusting (e.g., enlarging) the range, and is disposed in each of the laser elements 2. The lens 3 may be one that emits laser light emitted from the laser element 2 as substantially parallel light (substantially collimated light), or one that condenses the laser light.

  In the present embodiment, a case will be mainly described in which the laser light is substantially collimated by the lens 3 and applied to the light emitting unit 4. In this case, a plano-convex lens, a biconvex lens, an aspherical lens, or the like is used as the lens 3, and the positional relationship among the laser element 2, the lens 3, and the light emitting unit 4 is as shown in FIG.

  The laser element 2 is disposed at the focal position A of the lens 3. Specifically, the laser element 2 is arranged at the focal position A so as to coincide with the light emitting point 103 (see FIG. 3) of the laser element 2. In FIG. 4, the width l1 of the laser beam at the principal point of the lens 3 is 1.5 mm, the width l2 of the laser beam when the laser beam is applied to the light receiving surface 4a of the light emitting unit 4, and 2.0 mm. They are arranged such that the distance l3 between the lens 3 and the light emitting unit 4 is 50 mm. In the figure, the distance l3 is sufficiently longer than the widths l1 and l2 of the laser light, so that it can be regarded as almost parallel light.

  The lens 3 may be a biconvex lens, and the laser light may be condensed on the light emitting unit 4 side by the biconvex lens. This case will be described later with reference to FIG.

(Light emitting part 4)
The light emitting unit 4 has a light receiving surface 4a for receiving the laser light emitted from the laser element 2, and emits fluorescence upon receiving the laser light on the light receiving surface 4a. (Fluorescent substance). Specifically, the light emitting unit 4 is one in which a phosphor is dispersed inside a sealing material, or a phosphor is solidified. The light emitting unit 4 can be said to be a wavelength conversion element because it converts laser light into fluorescence.

  The light emitting section 4 has a cylindrical structure with a diameter of 2 mm and a height (thickness) of 0.2 mm. It is preferable that the diameter and height of the light emitting unit 4 are determined in consideration of the use efficiency of fluorescence, the predetermined light amount, and the radiation efficiency. In the present embodiment, the arrangement positions of the laser elements 2, the lenses 3, and the light emitting units 4 are determined so that the major axis of the irradiation region 34 on the light receiving surface 4a is 2 mm, that is, the same as the diameter of the light receiving surface 4a. Yes. Specifically, after the laser element 2 is arranged in the vicinity of the focal position of the lens 3, the light emitting unit 4 has the focal position of the parabolic mirror 5 so that the length of the major axis of the irradiation region 34 becomes the diameter of the light receiving surface 4 a. Placed in. In other words, the length of the major axis of the irradiation region 34 is substantially equal to the length between the two most distant points on the outer periphery of the light receiving surface 4a (in this embodiment, the diameter of the light receiving surface 4a). The placement position has been determined.

  In this case, when the length of the major axis of the irradiation region 34 is shorter than the distance between the two most distant points on the outer periphery of the light receiving surface 4a, the irradiation region 34 becomes smaller than the case of substantially matching. Therefore, the light density becomes unnecessarily high, and there is a concern about abnormal heat generation in the light emitting unit 4. In the present embodiment, since the two lengths are substantially the same, there is no possibility that the light emitting unit 4 generates heat abnormally.

  On the other hand, when the length of the major axis of the irradiation region 34 is longer than the distance between the two most distant points on the outer periphery of the light receiving surface 4a, the laser light is emitted from unnecessary regions other than the light receiving surface 4a (for example, the metal base 7). ), The phosphor contained in the light emitting unit 4 cannot be excited using the excitation light that is irradiated to the region. In the present embodiment, since the two lengths substantially coincide with each other, the laser light can be used for light emission of the light emitting unit 4 without waste, and the reduction of the irradiation efficiency of the laser light on the light receiving surface 4a can be prevented. it can.

  That is, in this embodiment, the arrangement of the laser elements 2 and the like is determined so that the length of the major axis of the irradiation region 34 becomes the diameter (2 mm) of the light receiving surface 4a, but the excitation efficiency of the light emitting unit 4 is reduced. And the arrangement | positioning should just be determined so that the fall of the irradiation efficiency with respect to the light-receiving surface 4a of a laser beam can be prevented. That is, if it is possible to prevent a decrease in the excitation efficiency and the irradiation efficiency, the length of the major axis of the irradiation region 34 is not the same as the diameter of the light receiving surface 4a, for example, slightly shorter than the diameter. A laser element 2 or the like may be disposed. In other words, the two lengths only need to be “substantially coincident” to the extent that reduction in excitation efficiency and irradiation efficiency can be prevented. In other words, the length of the major axis of the irradiation region 34 does not have to coincide with the length between the two most distant points on the outer periphery of the light receiving surface 4a, and the light emitting unit 4 so that the entire irradiation region 34 is included. The length of the major axis of the irradiation region 34 may be equal to or less than the length between the two most distant points on the outer periphery of the light receiving surface 4a.

  Further, the irradiation region 34 is determined so that the radiation angle of the light from the parabolic mirror 5 becomes a desired angle, and the size of the light emitting unit 4 is determined so that the irradiation region 34 is entirely included.

  The light emitting unit 4 is disposed on the metal base 7 and at a substantially focal position of the parabolic mirror 5. In other words, the center of the light emitting unit 4 substantially coincides with the focal position of the parabolic mirror 5. Therefore, the fluorescence emitted from the light emitting unit 4 is reflected on the reflection curved surface of the parabolic mirror 5 so that the optical path is controlled. An antireflection structure that prevents reflection of laser light may be formed on the upper surface of the light emitting unit 4.

  As the phosphor of the light emitting unit 4, for example, an oxynitride phosphor (for example, sialon phosphor) or a III-V group compound semiconductor nanoparticle phosphor (for example, indium phosphorus: InP) can be used. These phosphors have high heat resistance against high-power (and / or light density) laser light emitted from the laser element 2, and are optimal for laser illumination light sources. However, the phosphor of the light emitting unit 4 is not limited to the above-described phosphor, and may be another phosphor such as a nitride phosphor.

  In addition, the law stipulates that the illumination light of the headlamp must be white having a predetermined range of chromaticity. For this reason, the light emitting unit 4 includes a phosphor selected so that the illumination light is white.

  For example, when blue, green, and red phosphors are included in the light emitting unit 4 and irradiated with laser light of 405 nm, white light is generated. Alternatively, a yellow phosphor (or green and red phosphor) is included in the light-emitting portion 4, and a so-called blue laser having a peak wavelength in a wavelength range of 450 nm (blue) to 450 nm (blue) or 440 nm to 490 nm. White light can also be obtained by irradiating light.

  The sealing material of the light emitting unit 4 is, for example, a resin material such as a glass material (inorganic glass or organic-inorganic hybrid glass) or a silicone resin. Low melting glass may be used as the glass material. The sealing material is preferably highly transparent, and when the laser beam has a high output, a material having high heat resistance is preferable.

(Parabolic mirror 5)
The parabolic mirror 5 reflects the fluorescence generated by the light emitting unit 4 and forms a light bundle (illumination light) that travels within a predetermined solid angle. The parabolic mirror 5 may be, for example, a member having a metal thin film formed on the surface thereof or a metal member.

  FIG. 5 is a conceptual diagram showing the paraboloid of the parabolic mirror 5, FIG. 6 (a) is a top view of the parabolic mirror 5, (b) is a front view, and (c) is a side view. FIGS. 6A to 6C show an example in which the parabolic mirror 5 is formed by hollowing out the inside of a rectangular parallelepiped member so as to easily illustrate the drawings.

  As shown in FIG. 5, the parabolic mirror 5 is obtained by cutting a curved surface (parabolic curved surface) formed by rotating the parabola around the axis of symmetry of the parabola with a plane including the rotational axis. The partial curved surface is at least partially included in the reflecting surface. 6A and 6C, the curve indicated by reference numeral 5a indicates a parabolic surface. As shown in FIG. 6B, when the parabolic mirror 5 is viewed from the front, the opening 5b (exit of illumination light) is a semicircle.

  Part of the parabolic mirror 5 having such a shape is disposed above the upper surface of the light emitting unit 4 having a larger area than the side surface. That is, the parabolic mirror 5 is disposed at a position covering the upper surface of the light emitting unit 4. If it demonstrates from another viewpoint, a part of side surface of the light emission part 4 has faced the direction of the opening part 5b of the parabolic mirror 5. FIG.

  By making the positional relationship between the light emitting unit 4 and the parabolic mirror 5 as described above, the fluorescence of the light emitting unit 4 can be efficiently projected within a narrow solid angle, and as a result, the use efficiency of the fluorescence is increased. be able to.

  The laser element 2 is disposed outside the parabolic mirror 5, and the parabolic mirror 5 is formed with a window portion 6 that transmits or passes the laser light. The window 6 may be an opening or may include a transparent member that can transmit laser light. For example, a transparent plate provided with a filter that transmits laser light and reflects white light (fluorescence of the light emitting section 4) may be provided as the window section 6. In this configuration, the fluorescence of the light emitting unit 4 can be prevented from leaking from the window unit 6.

  One common window portion 6 may be provided for the plurality of laser elements 2, or a plurality of window portions 6 corresponding to the respective laser elements 2 may be provided.

  A part that is not a parabola may be included in a part of the parabola mirror 5. Moreover, the reflecting mirror included in the light emitting device of the present invention may include a parabolic mirror having a closed circular opening or a part thereof. The reflecting mirror is not limited to a parabolic mirror, and may be an elliptical mirror or a hemispherical mirror. That is, the reflecting mirror only needs to include at least a part of a curved surface formed by rotating a figure (ellipse, circle, parabola) about the rotation axis on the reflecting surface.

(Metal base 7)
The metal base 7 is a plate-like support member that supports the light emitting unit 4 and is made of metal (for example, copper or iron). Therefore, the metal base 7 has high thermal conductivity, and can efficiently dissipate heat generated by the light emitting unit 4. In addition, the member which supports the light emission part 4 is not limited to what consists of metals, The member containing substances (glass, sapphire, etc.) with high heat conductivity other than a metal may be sufficient. However, it is preferable that the surface of the metal base 7 in contact with the light emitting unit 4 functions as a reflecting surface. Since the surface is a reflecting surface, the laser light incident from the upper surface of the light emitting unit 4 is converted into fluorescence, and then reflected by the reflecting surface and can be directed to the parabolic mirror 5. Alternatively, the laser light incident from the upper surface of the light emitting unit 4 can be reflected by the reflecting surface and again directed to the inside of the light emitting unit 4 to be converted into fluorescence.

  Since the metal base 7 is covered with the parabolic mirror 5, it can be said that the metal base 7 has a surface facing the reflection curved surface (parabolic curved surface) of the parabolic mirror 5. It is preferable that the surface of the metal base 7 on the side where the light emitting unit 4 is provided is substantially parallel to the rotation axis of the paraboloid of the parabolic mirror 5 and substantially includes the rotation axis.

(Fin 8)
The fin 8 functions as a cooling unit (heat dissipation mechanism) that cools the metal base 7. The fin 8 has a plurality of heat radiating plates, and increases the heat radiation efficiency by increasing the contact area with the atmosphere. The cooling unit that cools the metal base 7 may have a cooling (heat dissipation) function, and may be a heat pipe, a water cooling method, or an air cooling method.

<Laser irradiation position on the light receiving surface 4a>
Next, the irradiation position of the laser beam on the light receiving surface 4a of the light emitting unit 4 according to the present embodiment will be described based on FIG. 1, FIG. 2 (a), and FIGS.

(About the intersection 35 formed by the intersection line 33)
First, FIG. 1 is a view showing a state of irradiation regions 34a and 34b formed on the light receiving surface 4a when laser light is emitted from the laser elements 2a and 2b. In FIG. 1, in order to simplify the explanation, a case where two laser elements 2a and 2b are arranged will be described as an example, but the case where three or more laser elements 2 are arranged is similarly explained. can do. Further, in FIG. 1, only the active layer 111 necessary for the description of the drawing is shown as the configuration of the laser elements 2a and 2b.

  Also, reference numerals 31a, 31b,... Are attached to the first plane including the active layer 111 included in the laser elements 2a, 2b,. Further, the intersection lines formed by the first planes 31a, 31b,... And the second plane 32 including the light receiving surface 4a are denoted by reference numerals 33a, 33b,. In addition, reference numerals 34a, 34b,... Are attached to irradiation regions formed on the light receiving surface 4a by laser light emitted from the laser elements 2a, 2b,. In addition, when not distinguishing that there are a plurality of first planes, irradiation regions, and intersection lines, reference numerals 31, 33, and 34 are assigned to the respective planes.

  In FIG. 1, the laser elements 2a and 2b each include an active layer 111, and first planes 31a and 31b including the respective active layers 111 and a second plane 32 including the light receiving surface 4a form intersecting lines 33a and 33b. is doing. The laser elements 2a and 2b and the light receiving surface 4a receive the laser light emitted from the active layers 111 of the laser elements 2a and 2b, respectively, that is, the light emitting point 103 of the active layer 111 receives light. It arrange | positions so that the surface 4a may be faced. With this arrangement, an intersection line 33 formed by the first plane 31 and the second plane 32 can be formed for each laser element 2.

  Note that the active layer 111 has an actual thickness but is very thin at 5 nm. Therefore, the active layer 111 will be described as having no thickness, that is, the first plane 31 includes the active layer 111. In consideration of the thickness of the active layer 111, a plane that is perpendicular to the front-side cleavage surface 114 (emission surface) and includes a part of the active layer 111 (passes through a part thereof) may be the first plane 31. .

  Here, as described above, since the light emitting point 103 is disposed so as to face the light receiving surface 4a, the irradiation region 34 of the laser light emitted from the laser element 2 is formed on the light receiving surface 4a. In this case, the situation where the intersecting lines 33 formed by the laser elements 2a and 2b are completely overlapped is that the portion where the irradiation regions 34 of the laser beams emitted from the individual laser elements 2 overlap is large. means. And since the emitted-heat amount will become large in the part, there exists a possibility that the light emission part 4 may be deteriorated.

  In the present embodiment, as shown in FIG. 1, the intersection lines 33 a and 33 b formed by the first planes 31 a and 31 b (each of the first plane 31) and the second plane 32 overlap at only one intersection point 35. In other words, two intersecting lines 33 selected from the plurality of intersecting lines 33 intersect at an angle greater than 0 ° and smaller than 180 °, and the intersecting lines 33 do not completely overlap each other. Since the intersection lines 33a and 33b do not overlap at locations other than the intersection point 35, the overlapping portion of the irradiation regions 34a and 34b can be reduced. For this reason, it can prevent that a laser beam is locally irradiated to one place of the light emission part 4 (light-receiving surface 4a), and can suppress the rapid heat_generation | fever in the light emission part 4. FIG. Therefore, since the deterioration of the light emitting unit 4 due to the heat generation can be suppressed, the life of the light emitting unit 4 can be extended. In addition, since it is possible to suppress a decrease in light emission efficiency of the light emitting unit 4 due to the heat generation, even in the headlamp 1 using a high output excitation light source, illumination light having a desired light quantity required by the headlamp 1 Can be realized.

  Here, it is conceivable to arrange the laser elements 2 so that the intersecting lines 33 formed by the plurality of first planes 31 and the second planes 32 are parallel to each other, but in this case, the light emission efficiency of the light emitting unit 4 is reduced. There is a possibility that. The reason is as follows.

  The light receiving surface 4a of the present embodiment has a circular shape. For example, when the diameter and the major axis of the irradiation region 34 are substantially matched, if the laser beam is irradiated to a position other than the diameter, the laser beam is irradiated to a portion other than the light receiving surface 4a. The laser beam irradiated to the part cannot be used for fluorescence conversion.

  On the other hand, when the light receiving surface 4a is rectangular (the light emitting portion 4 is a rectangular parallelepiped), unlike the circular shape, all of the irradiation regions 34 having predetermined long axes of the respective laser beams are accommodated in the light receiving surface 4a. Thus, each laser beam can be irradiated. However, in the present embodiment, in order to efficiently irradiate the parabolic mirror 5 with fluorescence, the light receiving surface 4a has a circular shape with a diameter of 2 mm. For this reason, even if fluorescence is generated for a portion that cannot be used for fluorescence conversion in the case of a circular shape and that can be used for conversion in the case of a rectangular shape, the parabola mirror 5 is appropriately irradiated with the fluorescence. It may not be possible. That is, since the fluorescent light that is not emitted within the predetermined range to be emitted by the headlamp 1 is generated, there is a possibility that the use efficiency of the fluorescent light is lowered.

  For this reason, if the shape of the light receiving surface 4a is taken into consideration, it can be said that it is not preferable to arrange the laser elements 2 so that the intersecting lines 33 are parallel to each other.

(Direction of laser element 2)
Here, the direction of the laser element 2 will be described with reference to FIG. FIG. 7 is a diagram illustrating an example of a state in which laser light is emitted from the laser element 2. FIG. 7A illustrates an intersection line 37 formed by the reference plane 36 and the first plane 31 provided for each laser element 2. FIG. 5 shows a case where the reference plane 36 is parallel to the x-axis, and FIG. 6B shows a case where the intersection line 37 formed by the reference plane 36 and the first plane 31 has an inclination. It is. The x axis is an axis parallel to the light receiving surface 4a, and the inclination of the intersection line 37 with respect to the x axis is equal to the inclination of the intersection line 37 with respect to the light receiving surface 4a.

  As described with reference to FIG. 3, the laser element 2 includes a plurality of layers, and emits laser light when the active layer 111 emits light among the layers. For this reason, even if the arrangement position of the laser element 2 is determined, if the laser element 2 rotates around the optical axis L at that position, the first plane 31 also rotates according to the rotation. For example, in FIG. 7A, when the reference plane 36 parallel to the front side cleaved surface 114 (exiting surface) of the laser element 2 is provided, the intersection between the first plane 31 including the active layer 111 and the reference plane 36 is made. The inclination of the line 37 in the reference plane 36 is 0 (parallel to the x axis). On the other hand, in FIG. 7B, the laser element 2 rotates around the optical axis L from the state of FIG. 7A, so that the inclination of the intersection line 37 on the reference plane 36 is -1. That is, the direction of the intersecting line 33 formed on the light receiving surface 4a (the direction of the irradiation region 34) is changed by the rotation of the laser element 2.

  For this reason, even if a plurality of laser elements 2 are arranged at different positions, if there is a variation in the direction of the active layer 111, the crossing lines 33 may completely overlap depending on the variation. In this case, a portion where the irradiation regions 34 overlap with each other becomes large, so that a heat generation amount as the light emitting unit 4 becomes large.

  Therefore, it is necessary to determine the arrangement of each laser element 2 in consideration of the direction of each active layer 111 so that the intersection line 33 does not completely overlap with the second plane 32 and forms the intersection point 35. In the present embodiment, the laser element 2 is arranged so that the angle formed by the center of the light receiving surface 4a and the position where each laser element 2 is arranged is the same when viewed from above the light receiving surface 4a. The inclinations of the intersecting lines 37 on the surface 36 (directions of the respective active layers 111) are adjusted so that the intersecting lines 33 do not completely overlap to form the intersecting point 35. Not limited to this, the inclination of each of the intersecting lines 37 on the reference plane 36 is made constant, and the position of each laser element 2 is adjusted, thereby forming the intersecting point 35 so that the intersecting lines 33 do not completely overlap each other. You may do it.

(Position relationship of intersection line 33)
Next, the positional relationship between the intersecting lines 33 (irradiation regions 34) formed on the light receiving surface 4a will be described with reference to FIG. 2, FIG. 8, and FIG. FIG. 8 is a diagram showing an irradiation region 34 formed on the light receiving surface 4a by the laser beam emitted from one laser element and its light intensity distribution. FIG. 9 shows an example of the positions of the intersection line 37, the intersection line 33, and the irradiation region 34 when the three laser elements 2a to 2c are arranged as shown in FIG. Indicates the angle between the axis a and each of the intersecting lines 37, and (b) indicates the positions of the intersecting line 33 and the irradiation region 34 formed on the second plane 32, respectively.

In the present embodiment, since the laser element 2 is disposed at the focal position of the lens 3, as shown in FIG. 8, the irradiation area 34 formed on the light receiving surface 4a is rectangular, and the laser beam in the irradiation area 34 is The light intensity has a Gaussian distribution (light intensity distribution having a sharp peak) with respect to the y-axis direction. In FIG. 8, the area of the irradiation region 34 is 2 × 0.5 mm ² .

  The arrows in the laser elements 2 a to 2 c in FIG. 2A are projected images of the active layers 111 of the laser elements 2 a to 2 c on the second plane 32, and indicate the inclinations of the intersecting lines 37 on the reference plane 36. Yes. When the laser elements 2a to 2c are arranged in this way, as shown in FIG. 9A, each of the intersecting lines 37 when the reference planes 36 formed by the laser elements 2a to 2c are overlapped is arbitrary. Are formed at positions θ1, θ2, and θ3 (θ1 ≠ θ2 ≠ θ3), respectively.

  For this reason, the positional relationship of the irradiation areas 34a, 34b, and 34c on the light receiving surface 4a is as shown in FIG. That is, the intersecting lines 33a, 33b and 33c formed by the first plane 31 formed by each of the laser elements 2a to 2c and the second plane 32 including the light receiving surface 4a are respectively θ1, θ2 and θ3 ( (θ1 ≠ θ2 ≠ θ3), that is, an angle formed between adjacent intersecting lines 33 is not 0 ° or 180 ° (π).

  That is, by arranging the laser elements 2a to 2c as shown in FIG. 2A, the intersection lines 33a to 33c overlap at the intersection point 35 as shown in FIG. 9B, but do not overlap at other points. Can be. In other words, the irradiation regions 34a to 34c formed by the laser beams emitted from the laser elements 2a to 2c can be prevented from overlapping each other except in the vicinity of the intersection 35, and the laser beams are irradiated locally. Heat generation due to can be avoided.

  2A and 2B, the case where there are three laser elements 2 has been described. However, the arrangement or activity of the laser elements 2 is such that the intersection lines 33 do not completely overlap but form an intersection point 35. If the direction of the layer 111 (inclination of the intersecting line 37) is adjusted, the number of the laser elements 2 may be two, or four as in another example below, or more. May be the number.

  In the present embodiment, the laser element 2, the lens 3, and the light emitting unit 4 are arranged so that the intersection point 35 formed by the intersection lines 33 is substantially the center of the light receiving surface 4a. It suffices if the intersection lines 33 are arranged so as not to completely overlap each other.

(Another example of the positional relationship of the intersection line 33)
Next, another example of the positional relationship between the intersecting lines 33 (irradiation regions 34) formed on the light receiving surface 4a will be described with reference to FIGS. FIG. 10 shows another example of a top view of the headlamp 1. FIG. 11 shows an example of the positions of the intersection line 37, the intersection line 33, and the irradiation region 34 when the four laser elements 2a to 2d are arranged as shown in FIG. Indicates the angle between the axis a and each of the intersecting lines 37, and (b) indicates the positions of the intersecting line 33 and the irradiation region 34 formed on the second plane 32, respectively.

  When the laser elements 2a to 2d are arranged as shown in FIG. 10 and the directions of the active layers 111 are adjusted, as shown in FIG. 11A, the reference planes 36 formed by the laser elements 2a to 2d are formed. Are respectively 0 from an arbitrary axis a (the axis a and the intersection line 37 of the laser element 2a are the same axis), θ2, θ3, and θ4 (0 ≠ θ2 ≠ θ3 ≠ θ4). ). Further, the direction of the active layer 111 is adjusted so that the angles formed by the intersecting lines 37 are equal. In FIG. 11A, all the angles formed by the intersecting lines 37 are θ2.

For this reason, the positional relationship of the irradiation areas 34a to 34d on the light receiving surface 4a is as shown in FIG. That is, of the intersecting lines 33a to 33d formed by the first plane 31 formed by each of the laser elements 2a to 2d and the second plane 32 including the light receiving surface 4a, the angle θ between the adjacent intersecting lines 33 is
The laser elements 2a to 2d are arranged in consideration of the direction of the active layer 111 so that θ (θ2 in FIG. 11A) = 180 ° / the number of laser elements 2 is satisfied. In FIG. 11B, the angle θ2 formed by the intersecting lines 33 is 45 °.

  When the laser element 2 is arranged as shown in FIG. 2A, the angle formed by the adjacent intersecting lines 33 is not constant as shown in FIG. 9B, so that the irradiation region 34 is formed on the light receiving surface 4a. A densely overlapping region 41 and a sparsely overlapping region 42 are formed. In this case, in the region 41, the amount of heat generation is larger than that in the other regions of the light emitting unit 4, so that the region 41 is easily deteriorated accordingly.

  By arranging the laser element 2 as shown in FIG. 10 and making the angle between the intersecting lines 37 (that is, the intersecting lines 33) constant, as shown in FIG. 11B, each irradiation region 34 on the light receiving surface 4a. Are formed uniformly (symmetric with respect to the intersection point 35). For this reason, since the part where the irradiation area | region 34 overlaps closely can be eliminated, the bias | inclination of the light intensity in the light-receiving surface 4a can be suppressed, and deterioration of the light emission part 4 by local heat_generation | fever can be suppressed. That is, in the case of FIG. 10, the deterioration of the light emitting unit 4 can be suppressed as compared with the case where the angle formed by the intersecting lines 33 is not considered as shown in FIG.

<Arrangement position of light emitting unit 4>
In FIG. 4 described above, it has been described that when the laser element 2 is disposed at the focal position A of the lens 3, the laser light transmitted through the lens 3 travels straight as almost parallel light. However, in the case of the biconvex lens of the lens 3, the laser light transmitted through the lens 3 may be condensed. Here, a method of determining the arrangement position of the light emitting unit 4 when the laser light transmitted through the lens 3 is a biconvex lens of the lens 3 will be described with reference to FIGS. 12 and 13.

  FIG. 12 is a schematic diagram of a biconvex lens. FIG. 13 shows an example of the positional relationship among the laser element 2, the lens 3 and the light emitting unit 4, and (a) shows a case where the light emitting unit 4 is arranged at a position shorter than the focal length of the lens 3. (B) shows a case where the light emitting section 4 is arranged at a position longer than the focal length of the lens 3.

The biconvex lens in FIG. 12 is used as the lens 3 and condenses the transmitted light at the focal position of the biconvex lens. This biconvex lens has a diameter (Φ) of 1.5 mm, the radius of curvature (R _LD ) of the convex lens on the laser element 2 side is 1.4 mm, and the radius of curvature (R _PH ) of the convex lens on the light emitting unit 4 side is 1.0 mm. The thickness T is 1.6 mm, and the refractive index is 1.7.

  As shown in FIGS. 13A and 13B, when the laser element 2 is disposed at one focal position A of the biconvex lens (lens 3), the laser light having a Gaussian distribution (Gaussian shape) light intensity distribution. Irradiates the light-emitting portion 4 while maintaining the Gaussian distribution without dispersing the light intensity distribution even if it passes through the lens 3. In this case, since the light receiving surface 4a is irradiated with laser light having high light intensity, the light emission efficiency of the light emitting section 4 by the individual laser elements 2 can be increased.

  However, when the light emitting unit 4 is disposed at the focal position B, which is the other focal position, the length S2 of the major axis of the irradiation region 34 is shorter than the diameter S1 of the light receiving surface 4a, and accordingly, light emission is performed accordingly. Efficiency will decrease.

  Therefore, in order to make the diameter S1 of the light receiving surface 4a substantially coincide with the length S2 of the major axis of the irradiation region 34, the light emitting unit 4 is disposed between the principal point of the lens 3 and the focal position B in FIG. In FIG. 13B, the light emitting unit 4 is disposed on the side farther from the focal position B when viewed from the lens 3. In other words, the light emitting unit 4 is substantially coincident with the distance between the two most distant points on the outer periphery of the light receiving surface 4a on the other focal position B side of the lens 3 and the length of the long axis of the irradiation region 34. It is arranged at the position to do. For this reason, as described above, it is possible to prevent a decrease in the excitation efficiency of the light emitting unit 4 and the irradiation efficiency of the laser light receiving surface 4a.

[Embodiment 2]
The following will describe another embodiment of the present invention with reference to FIGS. In addition, about the member similar to Embodiment 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted. In the present embodiment, a headlamp 1a in which the individual laser elements 2 are not arranged at the focal position of the lens 3 will be described.

  First, in the headlamp 1a shown in FIG. 14, the direction of each active layer 111 (the arrow direction of the active layer 111) and the relative positions of the laser elements 2a to 2c and the lens 3 are the same as those in the headlamp 1 shown in FIG. Is different. In the headlamp 1a, a biconvex lens shown in FIG.

  As in the first embodiment, the laser elements 2a to 2c are arranged in consideration of the respective directions of the active layer 111 so that the intersecting lines 33 do not completely overlap each other. Further, in order to prevent a decrease in excitation efficiency of the light emitting unit 4 and a decrease in irradiation efficiency of the laser light on the light receiving surface 4a, the laser is set so that the length of the major axis of the irradiation region 34 matches the diameter (2 mm) of the light receiving surface 4a. The element 2, the lens 3 and the light emitting unit 4 are arranged.

  Here, the relationship between the relative positions of the laser element 2 and the lens 3 and the laser light irradiation region 34 will be described with reference to FIG. FIG. 15 is a diagram showing an irradiation region 34 formed on the light receiving surface 4a by laser light emitted from one laser element, and its light intensity distribution. FIG. 15A shows the laser element 2 placed at the focal position. (B) shows a case where the laser element 2 is deviated from the focal position.

  When the laser element 2 is disposed at the focal position of the lens 3, as shown in FIG. 15A, a rectangular irradiation region 34 is formed on the light receiving surface 4a as in the first embodiment, and the light receiving surface 4a. The light intensity distribution of the laser beam at is a Gaussian distribution. In addition, the laser element 2 etc. are arrange | positioned so that the magnitude | size of the irradiation area | region 34 in this embodiment may be a little larger than the magnitude | size of Embodiment 1 with 2 * 1.75mm.

  On the other hand, when these members are arranged so that the distance d between the laser element 2 and the lens 3 is shorter than the focal length and a biconvex lens is used as the lens 3 as shown in FIG. As shown in FIG. 15B, the irradiation region 34 has a shape (for example, an elliptical shape) having a larger area than the rectangle. That is, with such an arrangement, the light intensity distribution of the laser light on the light receiving surface 4a can be dispersed more than the Gaussian distribution (the Gaussian distribution can be broken). The light intensity distribution of the laser light on the light receiving surface 4a is more dispersed than the Gaussian distribution, so that heat generation in the irradiation region 34 formed by the laser light emitted from each laser element 2 can be suppressed.

  In FIG. 14, the distance d between the laser element 2 and the lens 3 is d = focal length−0.4 mm. That is, the laser element 2 and the lens 3 are disposed so as to be shorter by 0.4 mm than the focal length. When the laser element 2 and the lens 3 are disposed so as to have such a distance d, after the laser element 2 is disposed at the focal position of the lens 3 (after the just focus position), the lens 3 is placed on the laser element 2 side. Alternatively, the laser element 2 may be moved to the lens 3 side. FIG. 16A shows a state in which the laser light with the Gaussian distribution becomes a laser light dispersed more than the Gaussian distribution in the light emitting unit 4 by moving the lens 3 to the laser element 2 side.

  If the distance d between the laser element 2 and the lens 3 is made shorter than the focal length, the area of the irradiation region 34 becomes too large, and unnecessary members such as the metal base 7 are irradiated with laser light. As a result, the utilization efficiency of the laser beam is reduced. Therefore, in consideration of this point, it is preferable not to move the lens 3 by 2 mm or more from the just focus position shown in FIG. 16A (or to keep the laser element 2 close to the just focus position by 2 mm or more).

  FIG. 17 is a diagram illustrating the positions of the intersection line 33 and the irradiation region 34 formed on the second plane 32 when the laser element 2 and the lens 3 are arranged as in the present embodiment. Although the irradiation areas 34a to 34c are not rectangular but have an elliptical shape having a larger area, the intersection lines 33a to 33c are intersection points as in FIG. 9B or 11B of the first embodiment. 35 is formed. For this reason, also in the present embodiment, the irradiation regions 34a to 34c overlap in the vicinity of the intersection 35, but can be prevented from overlapping in other portions.

  In the case of the present embodiment, the light intensity distribution of the laser light in the light emitting unit 4 is more dispersed than the Gaussian distribution, so that the amount of heat generated in each irradiation region 34 can be suppressed. Therefore, in this embodiment, it is possible to reduce the amount of heat generated in each irradiation region 34 and to reduce the amount of heat generated by forming the plurality of irradiation regions 34 so as not to overlap. Compared to the case, the heat generation amount of the entire light emitting unit 4 can be further reduced.

  In the present embodiment, as long as the light intensity distribution of the laser light on the light receiving surface 4a can be dispersed more than the Gaussian distribution, the biconvex lens of another shape (for example, a biconvex surface) is not limited to the biconvex lens shown in FIG. The lens 3 having the same curvature radius may be used as the lens 3.

[Embodiment 3]
The following will describe still another embodiment of the present invention with reference to FIG. 16 and FIGS. Note that members similar to those in the first or second embodiment are denoted by the same reference numerals and description thereof is omitted. In the present embodiment, a headlamp 1b in which the individual laser elements 2 are not arranged at the focal position of the lens 3 will be described.

  First, in the headlamp 1b shown in FIG. 18, the relative positions of the laser elements 2a to 2c and the lens 3 are different from the headlamp 1a shown in FIG. d is longer. Other configurations are the same as those in the second embodiment.

  Here, the relationship between the relative positions of the laser element 2 and the lens 3 and the laser light irradiation region 34 will be described with reference to FIG. FIG. 19 is a diagram showing an irradiation region 34 formed on the light receiving surface 4a by laser light emitted from one laser element, and its light intensity distribution. FIG. 19A shows the laser element 2 placed at the focal position. (B) shows a case where the laser element 2 is deviated from the focal position. Since FIG. 19A is the same as FIG. 15A, description thereof is omitted.

  As shown in FIG. 18, when these members are arranged so that the distance d between the laser element 2 and the lens 3 is longer than the focal length, as shown in FIG. Is larger than the area of the rectangular irradiation region 34 shown in FIG. 19A and has a shape different from that in FIG.

  Specifically, in FIG. 19B, the light intensity distribution of the laser light on the light receiving surface 4a is more dispersed than the Gaussian distribution, and two light intensity portions 38 are irradiated in the light intensity distribution. It exists in the periphery of the region 34. In this case, since it is more dispersed than the Gaussian distribution, heat generation in the irradiation region 34 formed by the laser light emitted from each laser element 2 can be suppressed.

  In other words, in the headlamp 1b, a biconvex lens is used as the lens 3 in order to realize the irradiation of the laser light such that the portion 38 having a high light intensity exists at a different position in the irradiation region 34, and the laser element These members are arranged so that the distance d between 2 and the lens 3 is longer than the focal length of the lens 3.

  In the present embodiment, a case where two portions 38 with high light intensity are formed in the periphery of the irradiation region 34 will be described. However, the present invention is not limited to this, and there are a plurality of portions 38 with high light intensity. Also good. In other words, it is only necessary that a plurality of peaks (a portion 38 having a high light intensity) be formed in the light intensity distribution of the laser light on the light receiving surface 4a. For example, it is realized by changing the shape of the lens 3 or the relative positions of the laser element 2 and the lens 3.

  Further, if the distance d between the laser element 2 and the lens 3 is too longer than the focal length, the light intensity distribution as shown in FIG. 20 is obtained, and unnecessary members such as the metal base 7 are irradiated with the laser light. As a result, the utilization efficiency of the laser light is reduced. Therefore, in consideration of this point, it is preferable not to move the lens 3 by 2 mm or more from the just focus position shown in FIG. 16B (or keep it away from the just focus position by 2 mm or more to the laser element 2).

  In FIG. 18, the distance d between the laser element 2 and the lens 3 is d = focal length + 0.2 mm. That is, the laser element 2 and the lens 3 are arranged so as to be longer by 0.2 mm than the focal length. As in the second embodiment, when the laser element 2 and the lens 3 are arranged so as to have such a distance, after the laser element 2 is arranged at the just focus position, the lens 3 is moved to the light emitting unit 4 side and arranged. Alternatively, the laser element 2 may be arranged so as to move away from the lens 3. In FIG. 16B, by moving the lens 3 to the light emitting unit 4 side, the laser light having a Gaussian distribution is more dispersed than the Gaussian distribution in the light emitting unit 4, and the light intensity distribution has a portion with a high light intensity. It is shown that the laser beam 38 is present at two locations.

  FIG. 21 is a diagram illustrating the positions of the intersecting line 33 and the irradiation region 34 formed on the second plane 32 when the laser element 2 and the lens 3 are arranged as in the present embodiment. Although the irradiation regions 34a to 34c are not rectangular but have a shape having a larger area, the intersection lines 33a to 33c are the same as in FIGS. 9B, 11B, and 17 of the first embodiment. Forms an intersection 35. For this reason, although the irradiation areas 34a-34c overlap in the vicinity of the intersection 35, it can be prevented from overlapping in other places.

  Further, unlike the first and second embodiments, a plurality of portions 38 having a large light intensity are formed in the light intensity distribution of the laser light on the light receiving surface 4a, and therefore, as shown in FIG. Even if only 35 overlaps, that portion does not overlap one point near the intersection 35. For this reason, since the portion 38 with high light intensity overlaps at a plurality of positions, the amount of heat generated by the entire light emitting unit 4 can be further reduced as compared with the first and second embodiments.

[Others]
Hereinafter, application examples of the headlamps 1, 1a, and 1b will be described.

<Method of disposing headlamp 1>
FIG. 22 is a conceptual diagram showing the arrangement direction of the headlamp 1 when the headlamps 1, 1 a and 1 b are applied to the headlamp of the automobile (vehicle) 10. As shown in FIG. 22, the headlamp 1 may be disposed on the head of the automobile 10 so that the parabolic mirror 5 is positioned vertically downward. In this arrangement method, the front surface of the automobile 10 is illuminated sufficiently brightly, and the front lower side of the automobile 10 is also brightened due to the light projection characteristics of the parabolic mirror 5 described above.

  The headlamps 1, 1a, and 1b may be applied to a traveling headlamp (high beam) for an automobile, or may be applied to a passing headlamp (low beam).

<Application example of the present invention>
The light emitting device of the present invention may be applied not only to a vehicle headlamp but also to other lighting devices. A downlight can be mentioned as an example of the illuminating device of this invention. A downlight is a lighting device installed on the ceiling of a structure such as a house or a vehicle. In addition, the lighting device of the present invention may be realized as a headlamp of a moving object other than a vehicle (for example, a human, a ship, an aircraft, a submersible, a rocket, etc.), or other than a searchlight, a projector, or a downlight. It may be realized as an indoor lighting fixture (such as a stand lamp).

<Another expression of the present invention>
The present invention can also be expressed as follows.

  That is, the light-emitting device according to the present invention includes two or more lasers for exciting the phosphor and a lens for condensing the laser on the surface of the light-emitter, and the difference between the laser installation angles does not become 0 and π, respectively. It is.

Further, the light emitting device according to the present invention has a configuration in which adjacent lasers form an angle of θ _step = 180 ° / number of lasers.

  Further, the light emitting device according to the present invention has a configuration in which the long axis of the beam spot on the upper surface of the light emitter matches the light emitter size.

  Further, the light emitting device according to the present invention is configured to determine the light emitter position so that the light emitter size and the long axis of the beam spot coincide with each other in a state where the LD is installed at the focal position of the lens.

  Further, the light emitting device according to the present invention has a configuration in which the light intensity distribution of the LD on the upper surface of the light emitter does not become a Gaussian distribution.

  Further, the light emitting device according to the present invention has a configuration in which the lens is shifted to the LD side from the focused state.

  In addition, the light emitting device according to the present invention is configured to shift the LD to the lens side from the focused state.

  Further, the light emitting device according to the present invention has a configuration in which a peak is obtained on the beam spot peripheral side in the light intensity of the LD on the upper surface of the light emitter.

  Further, the light emitting device according to the present invention has a configuration in which the lens is shifted to the opposite side of the LD from the focused state.

  In addition, the light emitting device according to the present invention is configured to shift the LD from the focused state to the opposite side of the lens.

  The present invention is not limited to the above-described embodiments and examples, and various modifications can be made within the scope shown in the claims, and obtained by appropriately combining technical means disclosed in different examples. Such embodiments are also included in the technical scope of the present invention.

  INDUSTRIAL APPLICABILITY The present invention can be applied to a light emitting device and a lighting device including the light emitting device, particularly a headlamp for a vehicle or the like, and suppresses deterioration of a light emitting unit included in the light emitting device and a decrease in light emission efficiency in the light emitting unit. Can do.

1, 1a, 1b Headlamp (light emitting device, vehicle headlamp, lighting device)
2 Laser element (excitation light source)
3. Lens (biconvex lens)
4 Light-Emitting Section 4a Light-Receiving Surface 31 First Plane 32 Second Plane 33 Intersection Line 34 Irradiation Area 38 Light Intensity (Peak)
111 Active layer (outgoing layer)
d Distance between laser element and lens (distance between excitation light source and biconvex lens)
A One focal position B Other focal position S1 Diameter of light receiving surface (length between two most distant points on the outer periphery of the light receiving surface)
S2 Long axis length of irradiated area

Claims (11)

A plurality of excitation light sources having an emission layer for emitting excitation light;
A light-receiving surface that receives the excitation light emitted from the excitation light source, and a light-emitting unit that emits light by receiving excitation light on the light-receiving surface,
A light emitting device characterized in that the intersecting lines formed by each of the first planes including the emission layer and the second plane including the light receiving surface do not completely overlap. A plurality of excitation light sources having an emission layer for emitting excitation light;
A light-receiving surface that receives the excitation light emitted from the excitation light source, and a light-emitting unit that emits light by receiving excitation light on the light-receiving surface,
Two intersecting lines selected from intersecting lines formed by the first planes including the emission layer and the second planes including the light receiving surface intersect at an angle greater than 0 ° and smaller than 180 °. A light emitting device characterized by that. When the angle between the intersecting lines formed by two adjacent excitation light sources is θ,
The light emitting device according to claim 1, wherein the excitation light sources are arranged so as to satisfy θ = 180 ° / the number of the excitation light sources. A biconvex lens that adjusts the range of the irradiation area on the light receiving surface,
The excitation light source is disposed at one focal position of the biconvex lens,
The light emitting unit is disposed on the other focal position side of the biconvex lens and at a position where the length of the long axis of the irradiation region substantially coincides with the distance between the two most distant points on the outer periphery of the light receiving surface. The light-emitting device according to claim 1, wherein the light-emitting device is provided.   4. The light emitting device according to claim 1, wherein a light intensity distribution of the excitation light on the light receiving surface is more dispersed than a Gaussian distribution. 5. A biconvex lens that adjusts the range of the irradiation area on the light receiving surface,
6. The light emitting device according to claim 5, wherein the excitation light source or the biconvex lens is arranged so that a distance between the excitation light source and the biconvex lens is shorter than a focal length of the biconvex lens.   6. The light emitting device according to claim 5, wherein a plurality of peaks are formed in the light intensity distribution of the excitation light on the light receiving surface. A biconvex lens that adjusts the range of the irradiation area on the light receiving surface,
The light-emitting device according to claim 7, wherein the excitation light source or the biconvex lens is arranged so that a distance between the excitation light source and the biconvex lens is longer than a focal length of the biconvex lens.   7. The length of the major axis of the irradiation area on the light receiving surface is substantially the same as the length between the two most distant points on the outer periphery of the light receiving surface. The light emitting device according to 1.   A vehicle headlamp comprising the light-emitting device according to claim 1.   An illumination device comprising the light-emitting device according to claim 1.

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