JP2011243370A - Light emitting device, illuminating device, and vehicle headlamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact light source which has high luminance and has a long lifetime without reducing luminous intensity of emitted light.SOLUTION: A light emitting device includes: a semiconductor laser diode for emitting a laser beam; an optical fiber having at least one incident end for receiving the laser beam emitted from the semiconductor laser diode and a plurality of emitting ends 5a for emitting the laser beam incident from the incident end; and a light-emitting section 7 for emitting light by receiving the laser beam emitted from the plurality of emitting ends 5a. The largest light intensity parts in light intensity distributions which exciting lights emitted from the plurality of emitting ends 5a have, respectively, are irradiated to mutually-different sections of the light-emitting section 7.

Description

  The present invention relates to a light-emitting device that functions as a high-intensity light source and an illumination device including the light-emitting device.

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.

  Examples of techniques relating to such a light emitting device include lamps disclosed in Patent Documents 1 and 2. In these lamps, a semiconductor laser is used as an excitation light source in order to realize a high-intensity light source. Since the laser light oscillated from the semiconductor laser is coherent light, the directivity is strong, and the laser light can be condensed and used as excitation light without waste. A light-emitting device using such a semiconductor laser as an excitation light source (referred to as an LD light-emitting device) can be suitably applied to a vehicle headlamp.

  On the other hand, as an example of a technique for realizing a vehicle headlamp using an incoherent white LED, there is a vehicle headlamp disclosed in Non-Patent Document 1.

  This Non-Patent Document 1 describes that the light distribution pattern (light distribution) of light generated from the light emitting part of the vehicle headlamp is narrow in the vertical direction and wide in the horizontal direction.

JP 2005-150041 A (released on June 9, 2005) JP 2003-295319 A (published on October 15, 2003)

Masaru Sasaki, “Application of White LED to Automotive Lighting”, Journal of Applied Physics, 2005, Vol. 74, No. 11, p. 1463-1466

  However, when a minute light-emitting part including a phosphor is excited with high-power excitation light that cannot be realized when an LED is used as an excitation light source (that is, when the light-emitting part is excited with very high excitation power and power density). The inventors of the present invention have found that there is a problem that the light emitting part is severely deteriorated.

  In order not to deteriorate the light emitting part, the intensity (unit: watts) of excitation light applied to the light emitting part may be reduced. However, with this method, the amount of light (flux) emitted from the light emitting unit is reduced, and it may not be possible to achieve the light intensity required for the light emitting device.

  Further, when an illumination device is realized using a conventional white LED, there is a problem that a single white LED has low luminance and light flux. When the luminance is low, the optical system needs to be enlarged, and when the luminous flux is small, it is necessary to integrate a plurality of white LEDs. As a result, there arises a problem that the lighting device is enlarged.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to realize a light source having a small size and a high brightness, and having a long lifetime without reducing the luminous flux of emitted light. It is providing the light-emitting device which can be performed, an illuminating device provided with the said light-emitting device, and a vehicle headlamp.

  In order to solve the above problems, a light-emitting device according to the present invention is configured to be excited from an excitation light source that emits excitation light, at least one incident end that receives the excitation light emitted from the excitation light source, and incident from the incident end. A light guide unit having a plurality of emission ends that emit excitation light; and a light emitting unit that emits light by receiving excitation light emitted from the plurality of emission ends, and is emitted from the plurality of emission ends. The portions having the highest light intensity in the light intensity distributions of the respective excitation light beams are irradiated to different portions of the light emitting portion.

  According to said structure, the excitation light which the excitation light source radiate | emitted enters into the incident end part of a light guide part, and is radiate | emitted from the several output end part of a light guide part. When the excitation light is applied to the light emitting part, the light emitting part emits light. At this time, the portions having the highest light intensity in the light intensity distributions of the excitation light emitted from the plurality of emission end portions are irradiated to the different portions of the light emitting portion. In other words, excitation light from a plurality of emission end portions is distributed and irradiated to the light emitting portion.

  Therefore, it is possible to reduce the possibility that the light emitting part is significantly deteriorated by intensively irradiating excitation light to one place of the light emitting part, and to realize a long-life light source without reducing the luminous flux of the emitted light. Can do. In addition, since it is not necessary to reduce the intensity of the excitation light applied to the light emitting unit, the luminance and light flux of the light emitting device can be increased. Therefore, a light emitting device with a small size and high luminance can be realized.

  The light emitting unit may include a light receiving surface that receives excitation light from the excitation light source, and may further include a holding unit that holds the plurality of emission end portions in a predetermined pattern with respect to the light receiving surface. preferable.

  According to said structure, a holding | maintenance part hold | maintains the several output end part which a light guide part has with a predetermined pattern with respect to the light-receiving surface of a light emission part. Therefore, even when the relative position between the light emitting portion and the light emitting portion is variable due to the reason that the light guide portion is flexible, the plurality of light emitting end portions are arranged with respect to the surface of the light emitting portion. Positioning with a predetermined pattern.

  As a result, the plurality of projected images on the light receiving surface formed by the light emitted from the plurality of light emitting ends form a predetermined pattern. By appropriately setting the predetermined pattern according to the purpose of the light emitting device, the light emitting unit can emit light in a preferable state. For example, the entire light emitting unit can emit light uniformly, or a part of the light emitting unit can emit light more strongly than other parts.

  Moreover, it is preferable that the light receiving surface has a long axis, and at least a part of the plurality of emission end portions is arranged along the long axis.

  The light distribution pattern of the vehicle headlamp is narrow in the vertical direction and wide in the horizontal direction. With the above configuration, the light emitting portion having the long axis is excited by a plurality of emission end portions arranged along the long axis, and thus the light distribution pattern can be realized. Since the setting of the light distribution pattern can be performed by the shape of the light emitting unit and the arrangement of the plurality of emission end portions, the light distribution pattern can be realized more easily than in the past.

  Moreover, it is preferable that the density of the emission end part arrange | positioned with respect to the said light-receiving surface is biased in the said light-receiving surface.

  With the above configuration, a part of the light emitting unit can emit light more strongly than the other parts. Therefore, it is possible to increase the luminous intensity of a part of the light beam emitted from the light emitting device. For example, when the present invention is applied to a headlamp of an automobile, the illuminance of a part of an area illuminated by the headlamp can be increased.

  Moreover, it is preferable that the said light guide part has flexibility.

  According to said structure, a light guide part is a member which has flexibility, for example, an optical fiber. Therefore, the positional relationship between the incident end and the emitting end can be easily changed, and the positional relationship between the excitation light source and the light emitting unit can be easily changed. Therefore, the design freedom of the light emitting device can be increased.

  The illuminating device according to the present invention includes the light emitting device and a reflecting mirror that reflects a light emitted from the light emitting unit to form a light bundle that travels within a predetermined solid angle.

  According to said structure, the light radiate | emitted from the light emission part is reflected by a reflective mirror, and the light beam which advances within the predetermined solid angle is formed. Therefore, a small, high-brightness, and long-life lighting device suitable for vehicle headlamps and searchlights can be realized.

  A vehicle headlamp according to the present invention includes the light-emitting device and a reflecting mirror that reflects a light emitted from the light-emitting unit to form a light bundle that travels within a predetermined solid angle. Yes.

  According to said structure, the light radiate | emitted from the light emission part is reflected by a reflective mirror, and the light beam which advances within the predetermined solid angle is formed. Therefore, a vehicle headlamp with a small size, high luminance and long life can be realized.

  As described above, the light emitting device according to the present invention emits excitation light that emits excitation light, at least one incident end that receives excitation light emitted from the excitation light source, and excitation light that is incident from the incident end. A light guide unit having a plurality of emission end portions and a light emitting unit that emits light by receiving excitation light emitted from the plurality of emission end portions, and the plurality of emission end portions are mutually connected to the light emission units. The excitation light is emitted to different parts.

  Therefore, it is possible to reduce the possibility that the light emitting part is significantly deteriorated by intensively irradiating the excitation light to one place of the light emitting part, and it is possible to realize a light source having a small size, high luminance, and long life. There is an effect.

It is a figure which shows the positional relationship of the emission end part and light emission part of an optical fiber with which the headlamp which concerns on one Embodiment of this invention is provided. It is sectional drawing which shows the structure of the headlamp which concerns on one Embodiment of this invention. It is sectional drawing which shows the example of a change of the positioning method of a light emission part. (A) And (b) is a figure which shows an example of the pattern which arrange | positions the several output end part 5a of an optical fiber with respect to the laser beam irradiation surface of a light emission part. (A) is a figure which shows light intensity distribution of the laser beam radiate | emitted from the output end part of an optical fiber, (b) is a figure which shows the positional relationship of several laser beam irradiation area | region. (A) is a figure which shows the circuit diagram of a semiconductor laser typically, (b) is a perspective view which shows the basic structure of a semiconductor laser. It is a perspective view which shows the structure of the semiconductor laser with which the headlamp which concerns on another form of this invention is provided. It is the schematic which shows the external appearance of the light emission unit with which the laser downlight which concerns on one Embodiment of this invention is equipped, and the conventional LED downlight. It is sectional drawing of the ceiling in which the said laser downlight was installed. It is sectional drawing of the said laser downlight. It is sectional drawing which shows the example of a change of the installation method of the said laser downlight. It is sectional drawing of the ceiling in which the said LED downlight was installed. It is a figure for comparing the specifications of the laser downlight and the LED downlight.

[Embodiment 1]
The following describes one embodiment of the present invention with reference to FIGS. Here, a headlamp (vehicle headlamp) 1 for an automobile will be described as an example of the illumination device of the present invention. However, the lighting device of the present invention may be realized as a headlamp of a vehicle other than an automobile or a moving object (for example, a human, a ship, an aircraft, a submersible craft, a rocket), or may be realized as another lighting device. Also good. Examples of other lighting devices include a searchlight, a projector, and a home lighting device.

  The headlamp 1 may satisfy the light distribution characteristic standard of the traveling headlamp (high beam), or may satisfy the light distribution characteristic standard of the passing headlamp (low beam).

(Configuration of headlamp 1)
FIG. 2 is a cross-sectional view showing the configuration of the headlamp 1. As shown in the figure, the headlamp 1 includes a semiconductor laser array (excitation light source) 2, an aspheric lens 4, an optical fiber (light guide part) 5, a ferrule (holding part) 6, a light emitting part 7, a reflecting mirror 8, and a transparent A plate 9, a housing 10, an extension 11 and a lens 12 are provided. The semiconductor laser array 2, the optical fiber 5, the ferrule 6 and the light emitting unit 7 form a basic structure of the light emitting device.

  The semiconductor laser array 2 functions as an excitation light source that emits excitation light, and includes a plurality of semiconductor lasers (semiconductor laser elements) 3 on a substrate. Laser light is oscillated from each of the semiconductor lasers 3. It is not always necessary to use a plurality of semiconductor lasers 3 as the excitation light source, and only one semiconductor laser 3 may be used. However, in order to obtain a high-power laser beam, it is preferable to use a plurality of semiconductor lasers 3.

  The semiconductor laser 3 has one light emitting point in one chip, for example, oscillates a laser beam of 405 nm (blue violet), has an output of 1.0 W, an operating voltage of 5 V, and a current of 0.6 A. It is enclosed in a package with a diameter of 5.6 mm. The laser light oscillated by the semiconductor laser 3 is not limited to 405 nm, and may be any laser light having a peak wavelength in a wavelength range of 380 nm to 470 nm. If a high-quality short-wavelength semiconductor laser that oscillates laser light having a wavelength smaller than 380 nm can be manufactured, the laser light having a wavelength smaller than 380 nm is oscillated as the semiconductor laser 3 of the present embodiment. It is also possible to use a semiconductor laser designed as described above.

The aspherical lens 4 is a lens for causing laser light (excitation light) oscillated from the semiconductor laser 3 to enter an incident end 5 b that is one end of the optical fiber 5. For example, as the aspheric lens 4, FLKN1 405 manufactured by Alps Electric can be used. The shape and material of the aspherical lens 4 are not particularly limited as long as the lens has the above function, but it is preferably a material having a high transmittance near 405 nm and a good heat resistance.

  The optical fiber 5 is a light guide member that guides the laser light oscillated by the semiconductor laser 3 to the light emitting unit 7 and is a bundle of a plurality of optical fibers. The optical fiber 5 has a plurality of incident end portions 5b that receive the laser light and a plurality of emission end portions 5a that emit the laser light incident from the incident end portion 5b. The plurality of emission end portions 5 a emit laser beams to different regions on the laser beam irradiation surface (light receiving surface) 7 a (see FIG. 1) of the light emitting unit 7. More specifically, the portion with the highest light intensity in the light intensity distribution (see FIG. 5A) of the laser beams emitted from the plurality of emission ends 5a is different from the different portions of the light emitting unit 7. Irradiated. The emission end portion 5a may be in contact with the laser light irradiation surface 7a or may be disposed at a slight interval.

  The optical fiber 5 has a two-layer structure in which an inner core is covered with a clad having a refractive index lower than that of the core. The core is mainly composed of quartz glass (silicon oxide) having almost no absorption loss of laser light, and the clad is composed mainly of quartz glass or a synthetic resin material having a refractive index lower than that of the core. . For example, the optical fiber 5 is made of quartz having a core diameter of 200 μm, a cladding diameter of 240 μm, and a numerical aperture NA of 0.22. However, the structure, thickness, and material of the optical fiber 5 are limited to those described above. Instead, the cross section perpendicular to the long axis direction of the optical fiber 5 may be rectangular.

  In addition, you may use what combined members other than an optical fiber, or an optical fiber and another member as a light guide member. The light guide member only needs to have at least one incident end that receives laser light oscillated by the semiconductor laser 3 and a plurality of emission ends that emit laser light incident from the incident end. For example, an incident part having at least one incident end part and an emitting part having a plurality of outgoing end parts may be formed as members different from the optical fiber, and the incident part and the outgoing part may be connected to both ends of the optical fiber. Good.

  FIG. 1 is a diagram showing a positional relationship between the emission end portion 5 a and the light emitting portion 7. As shown in the figure, the ferrule 6 holds a plurality of emission end portions 5 a of the optical fiber 5 in a predetermined pattern with respect to the laser light irradiation surface 7 a of the light emitting unit 7. The ferrule 6 may be formed with holes for inserting the emission end portion 5a in a predetermined pattern, and can be separated into an upper part and a lower part, and is formed on the upper and lower joint surfaces, respectively. The exit end portion 5a may be sandwiched by a groove.

  The ferrule 6 may be fixed to the reflecting mirror 8 by a rod-like or cylindrical member extending from the reflecting mirror 8. The material of the ferrule 6 is not specifically limited, For example, it is stainless steel. A plurality of ferrules 6 may be arranged for one light emitting unit 7. In FIG. 1, for convenience, three emission end portions 5a are shown, but the number of emission end portions 5a is not limited to three. Details of the number and arrangement of the emission end portions 5a will be described later.

  The light emitting section 7 emits light upon receiving the laser light emitted from the emission end 5a, and includes a phosphor that emits light upon receiving the laser light. Specifically, the light emitting unit 7 is a phosphor in which a phosphor is dispersed inside a silicone resin as a phosphor holding substance. The ratio of silicone resin to phosphor is about 10: 1. In addition, the light emitting unit 7 may be formed by pressing a fluorescent material. The phosphor holding substance is not limited to silicone resin, and may be so-called organic-inorganic hybrid glass or inorganic glass.

The phosphor is of an oxynitride type, and blue, green and red phosphors are dispersed in a silicone resin. Since the semiconductor laser 3 oscillates 405 nm (blue-violet) laser light, white light is generated when the light emitting unit 7 is irradiated with the laser light. Therefore, it can be said that the light emitting portion 7 is a wavelength conversion material.

  The semiconductor laser 3 may oscillate a 450 nm (blue) laser beam (or a so-called “blue” laser beam having a peak wavelength in a wavelength range of 440 nm to 490 nm). The phosphor is a yellow phosphor or a mixture of a green phosphor and a red phosphor. In other words, the semiconductor laser 3 may emit excitation light having a peak wavelength in the wavelength range of 440 nm or more and 490 nm or less. In this case, the light emitting part material (phosphor material) for generating white light is used. Easy to select and manufacture. The yellow phosphor is a phosphor that emits light having a peak wavelength in a wavelength range of 560 nm to 590 nm. The green phosphor is a phosphor that emits light having a peak wavelength in a wavelength range of 510 nm or more and 560 nm or less. The red phosphor is a phosphor that emits light having a peak wavelength in a wavelength range of 600 nm to 680 nm.

The phosphor is preferably a so-called sialon phosphor. Sialon is a substance in which a part of silicon atoms in silicon nitride is replaced with aluminum atoms and a part of nitrogen atoms is replaced with oxygen atoms. The sialon phosphor can be made by dissolving alumina (Al ₂ O ₃ ), silica (SiO ₂ ), rare earth elements, and the like in silicon nitride (Si ₃ N ₄ ).

As another preferred example of the phosphor, a semiconductor nanoparticle phosphor using nanometer-sized particles of a III-V group compound semiconductor can also be used. One of the characteristics of semiconductor nanoparticle phosphors is that even if the same compound semiconductor (for example, indium phosphorus: InP) is used, the emission color can be changed by the quantum size effect by changing the particle diameter. is there. For example, InP emits red light when the particle size is about 3 to 4 nm. Here, the particle size was evaluated with a transmission electron microscope (TEM).

  In addition, since this phosphor is semiconductor-based, it has a short fluorescence lifetime, and can quickly radiate excitation light power as fluorescence, so that it is highly resistant to high-power excitation light. This is because the emission lifetime of the semiconductor nanoparticle phosphor is about 10 nanoseconds, which is five orders of magnitude smaller than that of a normal phosphor material having a rare earth-based emission center. Since the emission lifetime is short, absorption of excitation light and emission of fluorescence can be repeated quickly.

  As a result, high efficiency can be maintained against strong excitation light, and heat generation from the phosphor is reduced. Therefore, it is possible to further suppress the light conversion member from being deteriorated (discolored or deformed) by heat. Thereby, when using the light emitting element with a high light output as a light source, it can suppress more that the lifetime of a light-emitting device becomes short.

The shape and size of the light emitting unit 7 are, for example, a rectangular parallelepiped of 3 mm × 1 mm × 1 mm. In this case, the area of the laser light irradiation surface 7a that receives the laser light from the semiconductor laser 3 is 3 mm ² . The light distribution pattern (light distribution) of a vehicle headlamp that is legally regulated in Japan is narrow in the vertical direction and wide in the horizontal direction. By making the cross section substantially rectangular), the light distribution pattern can be easily realized. The light emitting unit 7 does not have to be a rectangular parallelepiped, and may have a cylindrical shape in which the laser light irradiation surface 7a is an ellipse. Further, the laser light irradiation surface 7a is not necessarily a flat surface, and may be a curved surface. However, in order to control the reflection of the laser beam, the laser beam irradiation surface 7a is preferably a plane perpendicular to the optical axis of the laser beam.

Further, as shown in FIG. 2, the light emitting portion 7 is fixed at a position facing the emission end portion 5a on the inner surface of the transparent plate 9 (the side where the emission end portion 5a is located). The method for fixing the position of the light emitting unit 7 is not limited to this method, and the position of the light emitting unit 7 may be fixed by a rod-like or cylindrical member extending from the reflecting mirror 8.

  FIG. 3 is a cross-sectional view showing a modified example of the positioning method of the light emitting unit 7. As shown in the figure, the light emitting section 7 may be fixed to the tip of a cylindrical section 15 extending through the center of the reflecting mirror 8. In this case, the emission end portion 5 a of the optical fiber 5 can be passed through the cylindrical portion 15.

  The reflecting mirror 8 reflects the light emitted from the light emitting unit 7 to form a light beam that travels within a predetermined solid angle. That is, the reflecting mirror 8 reflects the light from the light emitting unit 7 to form a light beam that travels forward of the headlamp 1. The reflecting mirror 8 is, for example, a curved (cup-shaped) member having a metal thin film formed on the surface thereof.

  The transparent plate 9 is a transparent resin plate that covers the opening of the reflecting mirror 8, and holds the light emitting unit 7. The transparent plate 9 is preferably formed of a material that blocks the laser light from the semiconductor laser 3 and transmits white light (incoherent light) generated by converting the laser light in the light emitting unit 7. In addition to the resin plate, an inorganic glass plate can also be used. Most of the coherent laser light is converted into incoherent white light by the light emitting unit 7. However, there may be a case where a part of the laser beam is not converted for some reason. Even in such a case, the laser beam can be prevented from leaking to the outside by blocking the laser beam with the transparent plate 9. In addition, when such an effect is not expected and the light emitting unit 7 is held by a member other than the transparent plate 9, the transparent plate 9 can be omitted.

  The housing 10 forms the main body of the headlamp 1 and houses the reflecting mirror 8 and the like. The optical fiber 5 passes through the housing 10, and the semiconductor laser array 2 is installed outside the housing 10. The semiconductor laser array 2 generates heat when the laser light is oscillated, but the semiconductor laser array 2 can be efficiently cooled by being installed outside the housing 10. Moreover, since the semiconductor laser 3 may break down, it is preferable to install it at a position where it can be easily replaced. If these points are not taken into consideration, the semiconductor laser array 2 may be accommodated in the housing 10.

  The extension 11 is provided on the front side of the reflecting mirror 8 to improve the appearance by concealing the internal structure of the headlamp 1 and enhance the sense of unity between the reflecting mirror 8 and the vehicle body. The extension 11 is also a member having a metal thin film formed on the surface thereof, like the reflecting mirror 8.

  The lens 12 is provided in the opening of the housing 10 and seals the headlamp 1. The light generated by the light emitting unit 7 and reflected by the reflecting mirror 8 is emitted to the front of the headlamp 1 through the lens 12.

(Arrangement style of emission end 5a)
FIGS. 4A and 4B are diagrams illustrating an example of a pattern in which a plurality of emission end portions 5 a of the optical fiber 5 are arranged with respect to the laser light irradiation surface 7 a of the light emitting unit 7. In the figure, the position where the emission end portion 5a is in contact with (or is opposed to) the laser beam irradiation surface 7a is indicated by a circle. As shown in FIG. 6A, the laser light irradiation surface 7a of the light emitting unit 7 has a long axis, and at least a part of the plurality of emission end portions 5a is arranged along the long axis. Also good. Specifically, five exit end portions 5a may be densely arranged in two stages. With this configuration, the light emitting unit 7 that is long in the horizontal direction can be excited efficiently.

Further, as shown in FIG. 5B, the emission end 5a may be arranged in three stages only at the center of the laser light irradiation surface 7a. That is, the density of the plurality of emission end portions 5a arranged with respect to the laser light irradiation surface 7a of the light emitting unit 7 is biased in the laser light irradiation surface 7a. With this configuration, the central portion of the light-emitting portion 7 (the portion where the density of the emission end portion 5a is high) shines stronger than the other portions, so that the illuminance at the central portion of the region irradiated by the headlamp 1 can be increased.

  Further, a plurality of emission end portions 5a may be arranged in a matrix with respect to the entire surface of the laser light irradiation surface 7a of the light emitting unit 7. According to this configuration, the light emitting unit 7 can be excited efficiently and without unevenness.

(Positional relationship of laser light irradiation area)
A region where the laser beam emitted from one emitting end 5a is irradiated on the laser beam irradiation surface 7a of the light emitting unit 7 is referred to as a laser beam irradiation region. Since the optical fiber 5 has a plurality of emission end portions 5a, a plurality of laser light irradiation regions are also formed. FIG. 5A is a diagram showing a light intensity distribution of laser light emitted from the emission end portion 5a of the optical fiber 5, and FIG. 5B is a diagram showing a positional relationship between a plurality of laser light irradiation regions. . In FIG. 5A, the light intensity distribution of the laser light emitted from the emission end 5a of the optical fiber 51 constituting the optical fiber 5 is indicated by a curve 21, and the light of the laser light emitted from the emission end 5a of the optical fiber 52 is shown. The intensity distribution is shown by a curve 22. The horizontal axis of the graph in FIG. 5A indicates the position of the optical fiber 5, and the vertical axis indicates the light intensity of the laser light irradiated on the laser light irradiation surface 7a.

  As shown in FIG. 5A, the laser light emitted from one emitting end 5a reaches the laser light irradiation surface 7a while spreading at a predetermined angle. Therefore, even if the emission end portions 5a of the optical fibers 51 and 52 are arranged side by side in a plane parallel to the laser light irradiation surface 7a, as shown in FIG. The laser beam irradiation regions 23 and 24 formed by the laser beam may overlap each other.

  Even in such a case, the place where the light intensity is the highest in the light intensity distribution of the laser light emitted from the emission end 5a (near the central axes 21a and 22a shown in FIG. 5A) is the laser of the light emitting section 7. If the light is emitted to different portions of the light irradiation surface 7a, the laser light irradiation surface 7a can be irradiated in a two-dimensionally distributed manner.

  That is, the maximum light intensity portion (laser light) which is the portion having the highest light intensity in the projection image formed by irradiating the light emitting portion 7 with the laser light emitted from one of the plurality of emission end portions 5a. The position of the central portion of the irradiation region may be different from the position of the maximum light intensity portion of the projection image derived from the other emission end 5a. Therefore, it is not always necessary to completely separate the laser light irradiation regions from each other.

(Structure of semiconductor laser 3)
Next, the basic structure of the semiconductor laser 3 will be described. FIG. 6A schematically shows a circuit diagram of the semiconductor laser 3, and FIG. 6B is a perspective view showing the basic structure of the semiconductor laser 3. As shown in the figure, the semiconductor laser 3 has a configuration in which a cathode electrode 19, a substrate 18, a cladding layer 113, an active layer 111, a cladding 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 a substrate for a semiconductor laser, a group IV semiconductor represented by a group IV semiconductor 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.

  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. Generally, a mixed crystal semiconductor mainly composed of Al, Ga, In, As, P, N, and Sb is used as an active layer / cladding layer of a semiconductor laser, 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 7)
Next, the light emission principle of the phosphor by the laser light oscillated from the semiconductor laser 3 will be described.

  First, the laser light oscillated from the semiconductor laser 3 is irradiated onto the phosphor included in the light emitting unit 7, whereby electrons existing in the phosphor are excited from a low energy state to a high energy state (excited state).

  Since this excited state is unstable, the energy state of the electrons in the phosphor is changed to the original low energy state after a certain time (the energy state of the ground level or the level between the excited level and the ground level). Transition to a stable level energy state).

  In this way, the phosphors emit light when electrons excited to the high energy state transition to the low energy state.

  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, the color of the laser light emitted from the semiconductor laser and the phosphor White light can be generated by combining the color of emitted light as described above.

When ten semiconductor lasers 3 are provided and a laser beam of 405 nm is received from each of the semiconductor lasers 3, a luminous flux of 1500 lumen is emitted from the light emitting unit 7. The brightness in this case is 80 candela / mm ² .

(Effect of headlamp 1)
The inventors of the present invention have found that when the light emitting portion is excited with a laser beam having high power and high light density, the light emitting portion is severely deteriorated. Even if the light emitted from the LED is used as the excitation light, the same problem is considered to occur if the power is high and the light density is high. The deterioration of the light emitting part is mainly caused by the deterioration of the substance (for example, silicone resin) surrounding the phosphor together with the deterioration of the phosphor itself included in the light emitting part. The sialon phosphor described above generates light with an efficiency of 60 to 80% when irradiated with laser light, but the rest is emitted as heat. It is considered that the material surrounding the phosphor is deteriorated by this heat.

  In consideration of this problem, in the headlamp 1, at least a part of the laser light emitted from the emission end portion 5 a of the optical fiber 5 is irradiated to different regions on the laser light irradiation surface 7 a of the light emitting unit 7. . In other words, the laser beams from the plurality of emission ends 5a are distributed in a two-dimensional plane without being concentrated at one place with respect to the laser beam irradiation surface 7a, and are irradiated mildly.

  Therefore, it is possible to reduce the possibility that the light emitting unit 7 is significantly deteriorated by irradiating the light beam to one place of the light emitting unit 7 in a concentrated manner. At this time, the deterioration of the light emitting unit 7 can be prevented without lowering the luminous flux of the light emitted from the light emitting unit 7, and the long-life headlamp 1 can be realized while realizing the luminance required for the headlamp.

  Furthermore, since the light emitting unit 7 has a long life, the labor and cost for replacing the light emitting unit 7 can be reduced.

  Further, since the light emitting portion 7 that is wide in the horizontal direction is excited by a plurality of emission end portions arranged along the major axis, a light distribution pattern of the vehicle headlamp can be realized. Since the setting of the light distribution pattern can be performed by the shape of the light emitting unit 7 and the arrangement of the plurality of emission end portions 5a, the light distribution pattern can be realized more easily than in the past.

  Moreover, since the optical fiber 5 has flexibility, the arrangement | positioning with respect to the laser beam irradiation surface 7a of the output end part 5a can be changed easily. Therefore, the emission end portion 5a can be arranged along the shape of the laser beam irradiation surface 7a, and the laser beam can be irradiated mildly over the entire surface of the laser beam irradiation surface 7a.

  Moreover, since the optical fiber 5 has flexibility, the relative positional relationship between the semiconductor laser 3 and the light emitting unit 7 can be easily changed. Further, by adjusting the length of the optical fiber 5, the semiconductor laser 3 can be installed at a position away from the light emitting unit 7.

  Therefore, the degree of freedom in designing the headlamp 1 can be increased, for example, the semiconductor laser 3 can be installed at a position where it can be easily cooled or replaced.

  Moreover, by setting the arrangement pattern of the plurality of emission end portions 5a with respect to the laser light irradiation surface 7a of the light emitting unit 7, the illuminance of the region illuminated by the light from the light emitting unit 7 can be changed in the region. .

[Embodiment 2]
The following will describe another embodiment of the present invention with reference to FIG. In addition, about the member similar to Embodiment 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  Although the semiconductor laser 3 has one light emitting point on one chip, a semiconductor laser 3 having a plurality of light emitting points on one chip may be used as the excitation light source of the headlamp 1.

  FIG. 7 is a perspective view showing the configuration of the semiconductor laser 30. As shown in the figure, the semiconductor laser 30 has five light emitting points 31 on one chip. Each light emitting point 31 oscillates laser light having a wavelength of 405 nm, its output is 1 W, and the total light oscillated from one chip is 5 W. The light emitting points 31 are provided at intervals of 0.4 mm.

  When such a semiconductor laser 30 is used, the rod-shaped lens 32 is disposed at a position facing the surface where the light emitting point 31 of the semiconductor laser 30 exists. The rod-shaped lens 32 causes the laser light oscillated from the light emitting point 31 to enter the incident end portion 5 b of the optical fiber 5. Although the aspherical lens 4 may be provided at each of the light emitting points 31, the configuration of the semiconductor laser can be simplified by using the rod-shaped lens 32.

  The optical fiber fixture 33 positions the incident end portion 5b so that the laser light from the light emitting point 31 is incident on the plurality of incident end portions 5b. Since the interval between the light emitting points 31 is 0.4 mm, the incident end portion 5b is also fixed by the optical fiber fixture 33 at an interval of 0.4 mm. For this purpose, the optical fiber fixture 33 has grooves with a pitch of 0.4 mm.

  The configuration of the output end 5a side of the optical fiber 5 is the same as that of the first embodiment.

  By using the semiconductor laser 30 in this way, the structure of the excitation light source can be simplified, and the manufacturing cost of the excitation light source can be reduced.

[Embodiment 3]
The following will describe another embodiment of the present invention with reference to FIGS. In addition, about the member similar to Embodiment 1 * 2, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  Here, the laser downlight 200 as an example of the illuminating device of this invention is demonstrated. The laser downlight 200 is an illumination device installed on the ceiling of a structure such as a house or a vehicle, and uses fluorescence generated by irradiating the light emitting unit 7 with laser light emitted from the semiconductor laser 3 as illumination light. It is.

  Note that an illuminating device having the same configuration as that of the laser downlight 200 may be installed on the side wall or floor of the structure, and the installation location of the illuminating device is not particularly limited.

  FIG. 8 is a schematic view showing the appearance of the light emitting unit 210 and the conventional LED downlight 300. FIG. 9 is a cross-sectional view of the ceiling where the laser downlight 200 is installed. FIG. 10 is a cross-sectional view of the laser downlight 200. As shown in FIGS. 8 to 10, the laser downlight 200 is embedded in the top plate 400 and emits illumination light, and an LD light source unit that supplies laser light to the light emitting unit 210 via the optical fiber 5. 220. The LD light source unit 220 is not installed on the ceiling, but is installed at a position where the user can easily touch it (for example, a side wall of a house). The position of the LD light source unit 220 can be freely determined in this way because the LD light source unit 220 and the light emitting unit 210 are connected by the optical fiber 5. The optical fiber 5 is disposed in a gap between the top plate 400 and the heat insulating material 401.

(Configuration of light emitting unit 210)
As shown in FIG. 10, the light emitting unit 210 includes a housing 211, an optical fiber 5, a light emitting unit 7, and a light transmitting plate 213.

  A recess 212 is formed in the housing 211, and the light emitting unit 7 is disposed on the bottom surface of the recess 212. A metal thin film is formed on the surface of the recess 212, and the recess 212 functions as a reflecting mirror.

  In addition, a passage 214 for passing the optical fiber 5 is formed in the casing 211, and the optical fiber 5 extends to the light emitting unit 7 through the passage 214. The positional relationship between the emission end portion 5a of the optical fiber 5 and the light emitting portion 7 is the same as described above.

  The translucent plate 213 is a transparent or translucent plate disposed so as to close the opening of the recess 212. The translucent plate 213 has a function similar to that of the transparent plate 9, and the fluorescence of the light emitting unit 7 is emitted as illumination light through the translucent plate 213. The translucent plate 213 may be removable from the housing 211 or may be omitted.

  In FIG. 8, the light emitting unit 210 has a circular outer edge, but the shape of the light emitting unit 210 (more strictly, the shape of the housing 211) is not particularly limited.

  In the downlight, unlike a headlamp, an ideal point light source is not required, and a level of one light emitting point is sufficient. Therefore, there are fewer restrictions on the shape, size and arrangement of the light emitting section 7 than in the case of the headlamp.

(Configuration of LD light source unit 220)
The LD light source unit 220 includes a semiconductor laser 3, an aspheric lens 4, and an optical fiber 5.

  The incident end 5b, which is one end of the optical fiber 5, is connected to the LD light source unit 220, and the laser light oscillated from the semiconductor laser 3 is incident on the incident end 5b of the optical fiber 5 via the aspherical lens 4. Is incident on.

  Only one pair of the semiconductor laser 3 and the aspherical lens 4 is shown inside the LD light source unit 220 shown in FIG. 10, but when there are a plurality of light emitting units 210, the optical fibers 5 extending from the light emitting units 210 respectively. The bundle may be guided to one LD light source unit 220. In this case, a pair of a plurality of semiconductor lasers 3 and an aspheric lens 4 (or a pair of a plurality of semiconductor lasers 3 and one rod-shaped lens 32) is accommodated in one LD light source unit 220. The LD light source unit 220 functions as a central power supply box.

(Example of changing the installation method of the laser downlight 200)
FIG. 11 is a cross-sectional view showing a modified example of the installation method of the laser downlight 200. As shown in the figure, as a modified example of the installation method of the laser downlight 200, only a small hole 402 through which the optical fiber 5 passes is formed in the top plate 400, and the laser downlight main body (light emitting unit) is utilized by taking advantage of the thin and light weight. 210) can be attached to the top plate 400 using a strong adhesive tape or the like. In this case, there are advantages that restrictions on installation of the laser downlight 200 are reduced, and that construction costs can be significantly reduced.

(Comparison between laser downlight 200 and conventional LED downlight 300)
As shown in FIG. 8, the conventional LED downlight 300 includes a plurality of light transmitting plates 301, and illumination light is emitted from each light transmitting plate 301. That is, the LED downlight 300 has a plurality of light emitting points. The LED downlight 300 has a plurality of light emitting points because the light flux of light emitted from each light emitting point is relatively small. Therefore, if a plurality of light emitting points are not provided, light having a sufficient light flux as illumination light is provided. This is because it cannot be obtained.

  On the other hand, since the laser downlight 200 is an illumination device with a high luminous flux, the number of emission points may be one. Therefore, it is possible to obtain an effect that the shadow caused by the illumination light is clearly displayed. Moreover, the color rendering property of illumination light can be improved by making the phosphor of the light emitting portion 7 a high color rendering phosphor (for example, a combination of several kinds of oxynitride phosphors).

  FIG. 12 is a cross-sectional view of the ceiling where the LED downlight 300 is installed. As shown in the figure, in the LED downlight 300, a casing 302 that houses an LED chip, a power source, and a cooling unit is embedded in the top plate 400. The housing 302 is relatively large, and a recess along the shape of the housing 302 is formed in a portion of the heat insulating material 401 where the housing 302 is disposed. A power line 303 extends from the housing 302, and the power line 303 is connected to an outlet (not shown).

  Such a configuration causes the following problems. First, since there is a light source (LED chip) and a power source that are heat sources between the top plate 400 and the heat insulating material 401, the use of the LED downlight 300 raises the ceiling temperature, and the cooling efficiency of the room. Problem arises.

  Further, the LED downlight 300 requires a power source and a cooling unit for each light source, which causes a problem that the total cost increases.

  Moreover, since the housing | casing 302 is comparatively large, the problem that it is often difficult to arrange | position the LED downlight 300 in the clearance gap between the top plate 400 and the heat insulating material 401 arises.

  On the other hand, in the laser downlight 200, since the light emitting unit 210 does not include a large heat source, the cooling efficiency of the room is not reduced. As a result, an increase in room cooling costs can be avoided.

  Further, since it is not necessary to provide a power source and a cooling unit for each light emitting unit 210, the laser downlight 200 can be reduced in size and thickness. As a result, the space restriction for installing the laser downlight 200 is reduced, and installation in an existing house is facilitated.

  Further, since the laser downlight 200 is small and thin, as described above, the light emitting unit 210 can be installed on the surface of the top plate 400, and the space on the back side of the top plate is hardly required. It is possible to make the restrictions on installation smaller than 300 and to greatly reduce the construction cost.

  FIG. 13 is a diagram for comparing the specifications of the laser downlight 200 and the LED downlight 300. As shown in the figure, in the laser downlight 200, in one example, the volume is reduced by 94% and the mass is reduced by 86% compared to the LED downlight 300.

  In addition, since the LD light source unit 220 can be installed at a place (height) that can be easily reached by the user, the semiconductor laser 3 can be easily replaced even if the semiconductor laser 3 breaks down. Further, by guiding the optical fibers 5 extending from the plurality of light emitting units 210 to one LD light source unit 220, the plurality of semiconductor lasers 3 can be collectively managed. Therefore, even when a plurality of semiconductor lasers 3 are replaced, the replacement can be easily performed.

  In the case of a type using a high color rendering phosphor in the LED downlight 300, a light beam of about 500 lm can be emitted with a power consumption of 10 W, but in order to realize the light of the same brightness with the laser downlight 200, 3 .3W light output is required. If the LD efficiency is 35%, this light output corresponds to power consumption of 10 W, and the power consumption of the LED downlight 300 is also 10 W. Therefore, there is no significant difference in power consumption between the two. Therefore, in the laser downlight 200, the above-described various advantages can be obtained with the same power consumption as that of the LED downlight 300.

  As described above, the laser downlight 200 includes the light source unit 220 including at least one semiconductor laser 2 that emits laser light, the light emitting unit 7 and the at least one light emitting unit 210 including the concave portion 212 as a reflecting mirror, and light emission. And an optical fiber 5 for guiding the laser beam to each of the units 210.

  A plurality of emission end portions 5b of the optical fiber 5 are arranged with respect to one light emitting unit 7 included in the light emitting unit 210, and light intensity distributions respectively possessed by laser beams emitted from the plurality of arranged emission end portions 5b. The portion with the highest light intensity is irradiated to the different portions of the light emitting units 7 to be arranged.

  Therefore, in the laser downlight 200, it is possible to reduce the possibility that the light emitting unit 7 is significantly deteriorated by irradiating the laser light to one place of the light emitting unit 7 in a concentrated manner. As a result, a long-life laser downlight 200 can be realized.

(Example of change)
The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

For example, a high-power LED may be used as the excitation light source. In this case, a light emitting device that emits white light can be realized by combining an LED that emits light having a wavelength of 450 nm (blue) and a yellow phosphor or green and red phosphors.

  A solid-state laser other than the semiconductor laser may be used as the excitation light source. However, it is preferable to use a semiconductor laser because the excitation light source can be reduced in size.

  The present invention can also be expressed as follows.

  That is, the high-intensity light source of the present application has an excitation light source made of a semiconductor laser capable of high-power oscillation, and a light emitting portion that has a substantially rectangular shape that is long in the horizontal direction and emits light by excitation light from the excitation light source. And a light guide member for exciting the substantially rectangular light-emitting portion efficiently and without unevenness (not partially biased).

  The light guide member is a light guide member optically coupled to one or a plurality of excitation light sources, the other end having a plurality of light emission ends, and the plurality of light emission ends are light emitting devices having the substantially rectangular shape. It is (closely) aligned with one surface (substantially rectangular surface) of the part.

  The present invention can be applied to a light emitting device with high brightness and long life, particularly a headlamp for a vehicle or the like.

1 Headlamp (light emitting device, lighting device, vehicle headlamp)
2 Semiconductor laser array (excitation light source)
3 Semiconductor laser (excitation light source)
5 Optical fiber (light guide)
5a Output end portion 5b Incident end portion 6 Ferrule (holding portion)
7 Light emitting part 7a Laser light irradiation surface (light receiving surface)
8 Reflector 30 Semiconductor laser (excitation light source)
200 Laser downlight (lighting device)

Claims (7)

An excitation light source that emits excitation light;
A light guide having at least one incident end that receives the excitation light emitted from the excitation light source and a plurality of emission ends that emit the excitation light incident from the incident end;
A light emitting unit that emits light by receiving excitation light emitted from the plurality of emission ends,
A light emitting device characterized in that a portion having the highest light intensity in a light intensity distribution of excitation light emitted from the plurality of emission end portions is irradiated to different portions of the light emitting portion. The light emitting unit has a light receiving surface that receives excitation light from the excitation light source,
The light emitting device according to claim 1, further comprising a holding portion that holds the plurality of emission end portions in a predetermined pattern with respect to the light receiving surface.   The light emitting device according to claim 2, wherein the light receiving surface has a long axis, and at least a part of the plurality of emission end portions is arranged along the long axis.   4. The light emitting device according to claim 2, wherein the density of the emitting end arranged with respect to the light receiving surface is biased in the light receiving surface. 5.   The light-emitting device according to claim 1, wherein the light guide unit has flexibility. A light emitting device according to any one of claims 1 to 5,
An illuminating device comprising: a reflecting mirror that reflects light emitted from the light emitting unit to form a light bundle that travels within a predetermined solid angle. A light emitting device according to any one of claims 1 to 5,
A vehicular headlamp comprising: a reflecting mirror that reflects light emitted from the light emitting unit to form a light bundle that travels within a predetermined solid angle.

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