Source: https://patents.google.com/patent/JP5487077B2/en
Timestamp: 2019-11-19 03:40:16
Document Index: 224937955

Matched Legal Cases: ['art 4', 'art 5', 'art 4', 'art 4', 'art 4', 'art 4', 'art 4', 'art)\n10', 'art)\n26']

JP5487077B2 - Light emitting device, vehicle headlamp and lighting device - Google Patents
Light emitting device, vehicle headlamp and lighting device Download PDF
JP5487077B2
JP5487077B2 JP2010244570A JP2010244570A JP5487077B2 JP 5487077 B2 JP5487077 B2 JP 5487077B2 JP 2010244570 A JP2010244570 A JP 2010244570A JP 2010244570 A JP2010244570 A JP 2010244570A JP 5487077 B2 JP5487077 B2 JP 5487077B2
JP2010244570A
JP2012099280A (en
2010-10-29 Application filed by シャープ株式会社 filed Critical シャープ株式会社
2010-10-29 Priority to JP2010244570A priority Critical patent/JP5487077B2/en
2012-05-24 Publication of JP2012099280A publication Critical patent/JP2012099280A/en
2014-05-07 Publication of JP5487077B2 publication Critical patent/JP5487077B2/en
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.
An example of such a light emitting device is a vehicular lamp disclosed in Patent Document 1. In this vehicle lamp, an LED module or an LD module is used as an excitation light source, and white light is generated by irradiating excitation light onto a small spot-like phosphor having a diameter of about 0.5 mm or less. The generated white light is reflected forward by an elliptical spherical or parabolic reflector and is incident on the projection lens.
In the light source device disclosed in Patent Document 2, a collimator, a capacitor, and a phosphor are provided in front of the laser diode. The laser light, which is coherent light, passes through the collimator and the condenser and is concentrated and incident on the phosphor, and incoherent light is emitted from the phosphor.
Patent Document 3 discloses that when an optical fiber cannot be installed at the apex of the concave mirror, the optical fiber may be installed obliquely with respect to the center line connecting the focal point and the apex of the concave mirror.
Japanese Unexamined Patent Publication No. 2004-241142 (released on August 26, 2004) JP 2003-295319 A (published on October 15, 2003) Japanese Patent Laid-Open No. 7-318998 (released on December 8, 1995)
From the viewpoint of saving energy and extending the light emission duration of the light emitting device that emits light from the battery, it is important to reduce the power consumption of the light emitting device. As one of the measures for reducing the power consumption of the light emitting device, it is conceivable to increase the utilization efficiency of the fluorescence emitted by the light emitting unit.
However, the configuration for increasing the utilization efficiency is not disclosed or suggested in Patent Documents 1 to 3. For example, Patent Document 3 does not disclose or suggest at what angle laser light should be irradiated in order to increase the use efficiency of fluorescence.
The objective of this invention is providing the light-emitting device, the vehicle headlamp, and the illuminating device which can improve the utilization efficiency of fluorescence.
In order to solve the above problems, a light emitting device according to the present invention includes an excitation light source that emits excitation light, a light emitting unit that emits fluorescence upon receiving excitation light emitted from the excitation light source, and the light emitting unit And a part of the reflecting mirror is disposed above an upper surface having a larger area than a side surface of the light emitting unit, and the light emitting unit is thin or the light emitting unit. The incident angle of the excitation light with respect to the upper surface is set so that the area of the spot of the excitation light irradiated on the upper surface of the light source is smaller than the area of the upper surface and the use efficiency of the fluorescence emitted from the light emitting unit is increased It is characterized by that.
According to said structure, the light emission part emits fluorescence in response to the excitation light from an excitation light source, and the said fluorescence is radiate | emitted as illumination light by reflecting the fluorescence with a reflective mirror.
At this time, since the upper surface of the light emitting unit faces the reflecting mirror, the ratio of the fluorescence that can control the course of the fluorescence emitted from the light emitting unit can be increased.
Even in this case, the fluorescence emitted from the side surface of the phosphor (side emission fluorescence) can be controlled, and there is a high possibility that the light is projected to other than the front.
However, since the light emitting part is thin or the area of the surface that receives the excitation light is larger than the area of the spot of the excitation light, the side emission fluorescence is reduced. This has been confirmed by the inventors of the present invention. Therefore, with the above configuration, it is possible to reduce the fluorescence that cannot be controlled by the reflecting mirror, and it is possible to increase the use efficiency of the fluorescence.
In the case of the above-described light emitting unit, most of the fluorescence is emitted within a predetermined angular range. For this reason, if an opening for transmitting excitation light is provided on the reflecting surface of the reflecting mirror within this angular range, fluorescence cannot be reflected at this opening, resulting in a loss of fluorescence. In addition, when an excitation light source is disposed within a predetermined angle range, fluorescence is absorbed or diffused by the excitation light source, resulting in a loss of fluorescence.
Therefore, in the above configuration, the incident angle of the excitation light is set so that the utilization efficiency of the fluorescence emitted from the light emitting unit is increased (the loss of fluorescence is reduced). Therefore, a light emitting device with high utilization efficiency of fluorescence can be realized.
Moreover, it is preferable that the said incident angle is the range of 30 degrees or more and 80 degrees or less on the basis of the perpendicular standing on the said upper surface.
In the case of the above-described light emitting unit, about half of the fluorescence is emitted within an angle range of less than 30 ° with respect to a vertical line standing on the upper surface. For this reason, if an opening is provided on the reflecting surface of the reflecting mirror within the above range, the excitation light cannot be reflected at the opening, resulting in a loss of fluorescence. Further, when the excitation light source is disposed within the above range, fluorescence is absorbed or diffused by the excitation light source, resulting in a loss of fluorescence.
In addition, in the angle range greater than 80 ° and within 90 °, the excitation light is likely to be reflected on the surface of the light emitting portion, so that the use efficiency of the excitation light is reduced.
Therefore, the use efficiency of fluorescence can be increased by making the excitation light incident in the range of 30 ° to 80 °.
Moreover, it is preferable that the said incident angle is the range of 40 degrees or more and 70 degrees or less on the basis of the perpendicular standing on the said upper surface.
By limiting the incident angle of the excitation light to 40 ° or more and 70 ° or less, it is possible to further reduce the surface reflection at the light emitting portion while further reducing the influence of providing the opening in the reflecting mirror. Therefore, the utilization efficiency of fluorescence and excitation light can be further increased.
The excitation light is preferably P-polarized with respect to the upper surface.
Since the P-polarized light has a low reflectivity with respect to the upper surface of the light emitting unit, the utilization efficiency of the excitation light can be increased.
Moreover, it is preferable that the said incident angle is the range of 60 degrees or more and 65 degrees or less on the basis of the perpendicular standing on the said upper surface.
According to said structure, an incident angle turns into a Brewster angle. At the Brewster angle, the reflectance can be greatly reduced, so that the utilization efficiency of the excitation light can be increased.
By setting the thickness of the light emitting portion to be equal to or less than the above thickness, side emission fluorescence is almost eliminated, and the use efficiency of fluorescence can be further increased.
The reflecting mirror includes at least a part of a partial curved surface obtained by cutting a curved surface formed by rotating the parabola around the axis of symmetry of the parabola as a rotational axis along a plane including the rotational axis. It is preferable.
According to the above configuration, the reflecting mirror has a reflection curved surface obtained by cutting the parabola along a plane including the rotation axis, and a structure other than the parabola is disposed in a portion corresponding to the remaining half of the parabola. it can. If this structure is a plate having high thermal conductivity and the light emitting part is brought into contact, the heat of the light emitting part can be efficiently radiated.
In the above configuration, most of the fluorescence that could not be controlled by the reflecting mirror is emitted to the parabolic side. Utilizing this characteristic, the parabolic side of the light emitting device can be appropriately illuminated.
According to said structure, a light emission part can be cooled with a heat conductive member, and it can prevent that the luminous efficiency of a light emission part falls with the heat | fever of excitation light.
According to said structure, excitation light can be irradiated to a light emission part from the exterior of a reflective mirror through the window part provided in the reflective mirror. Therefore, the degree of freedom of arrangement of the excitation light source can be increased, and for example, the irradiation angle of the excitation light with respect to the irradiation surface of the light emitting unit can be easily set to a preferable angle.
Moreover, it is preferable to further include a magnifying lens that expands an irradiation range of the excitation light and irradiates the light emitting unit.
According to said structure, since excitation light is not irradiated locally to a light emission part, degradation of a light emission part can be suppressed.
Moreover, it is preferable that the light guide part which condenses the excitation light radiate | emitted from the said excitation light source and guides it to the said light emission part is arrange | positioned through the said window part.
According to the above configuration, light beams emitted from a plurality of excitation light sources or a plurality of light beams emitted from one excitation light source can be condensed and irradiated to the light emitting unit, and the power of the excitation light can be substantially increased. it can.
Moreover, it is preferable that an optical fiber for guiding the excitation light emitted from the excitation light source to the light emitting unit is disposed.
According to said structure, since the optical fiber has flexibility, the incident angle and incident direction of excitation light can be adjusted easily.
Moreover, the vehicle headlamp characterized by including the said light-emitting device and the illuminating device containing the said light-emitting device are also contained in the technical scope of this invention.
As described above, a light-emitting device according to the present invention includes an excitation light source that emits excitation light, a light-emitting unit that emits fluorescence in response to excitation light emitted from the excitation light source, and fluorescence generated by the light-emitting unit. And a part of the reflecting mirror is disposed above the upper surface of the light emitting unit having a larger area than the side surface, and the light emitting unit is thin or irradiates the upper surface of the light emitting unit. The excitation light spot area is smaller than the area of the upper surface, and the incident angle of the excitation light with respect to the upper surface is set so that the use efficiency of the fluorescence emitted from the light emitting portion is increased.
Therefore, there is an effect that the use efficiency of fluorescence can be increased.
It is sectional drawing which shows schematic structure of the headlamp which concerns on one Embodiment of this invention. It is a conceptual diagram which shows the paraboloid of a parabolic mirror. (A) is a top view of a parabolic mirror, (b) is a front view of the parabolic mirror, and (c) is a side view of the parabolic mirror. It is a figure which shows the state which irradiated the laser beam to the light emission part. (A) is a graph which shows the light emission characteristic when a light emission part is thin, (b) is a graph which overlaps and shows the light emission characteristic when a light emission part is thick to Fig.5 (a). It is a graph which shows the relationship between the thickness of a light emission part, and light emission characteristics. It is a figure which shows the state which irradiated the laser beam on the upper surface of the light emission part. (A) And (b) is a figure for demonstrating the incident angle of the laser beam with respect to the upper surface of a light emission part. (A) is a graph which shows the fluorescence spread distribution, (b) is a figure which shows the ratio with respect to the total light quantity of the integrated value of the fluorescence in each angle range. It is a figure which shows the positional relationship of the emission range of a laser beam, and a parabolic mirror. It is a graph which shows the change of the reflectance accompanying the change of the incident angle of the laser beam of S polarization and P polarization. It is a conceptual diagram which shows the light projection characteristic of a parabolic mirror. It is a figure for demonstrating the principle of the light projection characteristic of a parabolic mirror. It is a conceptual diagram which shows the arrangement | positioning direction of the headlamp in a motor vehicle. It is the schematic which shows the structure of the headlamp which concerns on one Example of this invention. It is the schematic which shows the structure of the headlamp which concerns on another Example of this invention. It is the schematic which shows the structure of the headlamp which concerns on another Example of this invention. It is a top view which shows arrangement | positioning of a several laser element. It is the schematic which shows the structure of the headlamp which concerns on another Example of this invention. It is the schematic which shows the structure of the headlamp which concerns on another Example of this invention. It is the schematic which shows the structure of the illuminating device which concerns on one Example of this invention. It is the schematic which shows the example of a change of this invention.
FIG. 1 is a cross-sectional view showing a schematic configuration of a headlamp 1 according to an embodiment of the present invention. As shown in FIG. 1, a headlamp 1 includes a laser element (excitation light source, semiconductor laser) 2, a magnifying lens 3, a light emitting unit 4, a parabolic mirror (reflecting mirror) 5, a metal base (thermally conductive member) 7, fins 8 is provided.
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 in FIG. When a plurality of laser elements 2 are provided, laser light as excitation light is oscillated from each laser element 2. Although only one laser element 2 may be used, it is easier to use a plurality of laser elements 2 in order to obtain a high-power laser beam.
The incident angle (angle θ in FIG. 1) of the laser light with respect to the upper surface 4a of the light emitting unit 4 is set so that the utilization efficiency of the fluorescence emitted from the light emitting unit 4 is increased. Specifically, the angle θ in FIG. 1 is preferably 30 ° or more and 80 ° or less. That is, the incident angle of the laser beam is preferably in the range of 30 ° or more and 80 ° or less with respect to a perpendicular line standing on the upper surface 4a. The reason why this angle range is preferable will be described later.
When a plurality of laser elements 2 are provided, it is preferable that the incident angles of the respective lasers are set so that the incident angles of the laser beams emitted from the respective laser elements 2 are all within the above-described angle range.
Further, from the viewpoint of reducing surface reflection, the laser light is preferably P-polarized light with respect to the upper surface 4 a of the light emitting unit 4. Details of this will be described later.
(Magnifying lens 3)
The magnifying lens 3 is a lens for enlarging the irradiation range of the laser beam so that the laser beam emitted from the laser element 2 is appropriately irradiated to the light emitting unit 4. ing.
The light emitting unit 4 emits fluorescence upon receiving the laser light emitted from the laser element 2, and includes a phosphor (fluorescent substance) that emits light upon receiving the laser light. 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 unit 4 is disposed on the metal base 7 and at a substantially 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.
The laser light is mainly applied to the upper surface 4a of the light emitting unit 4 at the above-described incident angle. An antireflection structure for preventing the reflection of laser light may be formed on the upper surface 4 a 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.
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.
Part of the parabolic mirror 5 having such a shape is disposed above the upper surface 4a 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 that covers the upper surface 4 a 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.
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 position where the window 6 is formed is determined by the incident angle of the laser light from the laser element 2. That is, the position of the window portion 6 is determined so that the incident angle of the laser beam with respect to the upper surface 4a of the light emitting portion 4 is in the above range. Specifically, the window portion 6 is formed outside an angle range of ± 30 ° from a vertical line standing on the upper surface 4 a of the light emitting portion 4.
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.
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.
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.
The preferable range of the incident angle of the laser beam is calculated on the assumption that almost no fluorescence is emitted from the side surface of the light emitting unit 4. Therefore, the shape of the light emitting unit 4 that hardly emits fluorescence from the side surface of the light emitting unit 4 will be described.
FIG. 4 is a diagram illustrating a state in which the light emitting unit 4 is irradiated with laser light. FIG. 4 shows a cylindrical light emitting unit 4. The light emitting unit 4 has an upper surface 4 a that mainly receives laser light, and the distance between the upper surface 4 a and the bottom surface that is the opposite surface is the thickness of the light emitting unit 4. The light emitting part 4 is preferably thin. In other words, it is preferable that the area of the side surface 4b of the light emitting unit 4 is small. “The light emitting portion is thin” means a shape of the light emitting portion in which the area of the side surface is sufficiently smaller than the upper surface of the light emitting portion, and most of the fluorescence is emitted upward (that is, from the upper surface). The reason why the light emitting portion 4 is preferably thin will be described next.
As shown in FIG. 5A, when the light emitting unit 4 is thin, the area of the side surface 4b is small, so that most of the fluorescence is emitted directly above the light emitting unit 4, and the upper surface 4a of the light emitting unit 4 There is almost no fluorescence emission in the direction of 90 ° (θ = ± 90 °) from the perpendicular line, and the fluorescence distribution is a Lambertian distribution (cosine θ distribution).
On the other hand, as shown in FIG. 5B, when the light emitting unit 4 is thick, fluorescence emission is generated in the direction of 90 ° (θ = ± 90 °) from the perpendicular standing on the upper surface 4a of the light emitting unit 4. The fluorescence distribution is not Lambertian distribution. That is, the ratio of the fluorescence emitted from the side surface 4b of the light emitting unit 4 is increased. A part of the fluorescence emitted from the side surface 4b of the light emitting unit 4 does not strike the parabolic mirror 5, but is emitted from the opening 5b of the parabolic mirror 5 and scattered in the space (see FIG. 13). Therefore, when the ratio of the fluorescence emitted from the side surface 4b of the light emitting unit 4 increases, the fluorescence that cannot be controlled by the parabolic mirror 5 increases, and the fluorescence utilization efficiency (and the laser light utilization efficiency) decreases.
(Area of the upper surface 4a of the light emitting part 4)
In order to obtain a Lambertian distribution of the fluorescence of the light emitting unit 4, the area of the spot of the laser light irradiated on the upper surface 4a of the light emitting unit 4 is set to be larger than the area of the upper surface 4a, in addition to making the light emitting unit 4 thinner. It may be small. That is, by exciting a part of the light emitting unit 4 (near the center) with laser light, the fluorescence distribution of the light emitting unit 4 can be a Lambertian distribution.
The ratio of the area of the laser beam spot to the area of the upper surface 4 a should be small enough that the laser beam does not leak from the side surface of the light emitting unit 4. There is no particular upper limit on the area of the upper surface 4a.
<Preferred incident angle of laser beam>
Next, a preferable range of the incident angle of the laser light will be described in detail. FIGS. 8A and 8B are diagrams for explaining the incident angle of the laser light with respect to the upper surface 4a of the light emitting unit 4. FIG. Assuming that the optical path of the laser beam does not have a width, as shown in FIG. 8A, the incident angle of the laser beam 2a with respect to the upper surface 4a of the light-emitting portion 4 is a perpendicular line standing on the upper surface 4a. Is the angle θ. The case where the optical path of the laser beam has a width will be described later.
FIG. 9A is a graph showing the fluorescence spread distribution, and FIG. 9B is a diagram showing the ratio of the integrated fluorescence value to the total light quantity in each angle range. FIG. 10 is a diagram showing the positional relationship between the laser light emission range and the parabolic mirror 5. As shown in FIGS. 9A and 9B, about 50% of the total luminous flux is emitted within an angle range of ± 30 ° from the perpendicular standing at the center of the upper surface 4 a of the light emitting unit 4.
Therefore, as shown in FIG. 10, if the window portion 6 is formed in the range of ± 30 ° (region indicated by reference numeral 5 c in FIG. 10), the fluorescence leaks from the window portion 6, resulting in a large loss of fluorescence. Even when the laser element 2 is arranged inside the parabolic mirror 5, if the laser element 2 is arranged within the range of ± 30 °, the fluorescence is absorbed or diffused by the laser element 2 and the loss of fluorescence increases. . Therefore, the lower limit value of the laser beam incident angle is 30 °. In other words, the window portion 6 is formed outside the range of ± 30 ° with respect to a perpendicular line standing at the center of the upper surface 4a of the light emitting portion 4 (substantially the focal point of the parabolic mirror 5).
On the other hand, as shown in FIG. 11, if the incident angle is too shallow, the reflectivity increases regardless of whether S-polarized (S-wave) or P-polarized (P-wave) laser light is used. It does not enter. FIG. 11 is a graph showing a change in reflectance of the S-polarized light and the P-polarized laser light with a change in incident angle. FIG. 11 shows the reflectance when a 405 nm laser beam is incident on the light emitting section 4 having a refractive index of 2.0. S-polarized light and P-polarized light mean the polarization direction with respect to the upper surface 4 a of the light emitting unit 4.
Considering the use of P-polarized light whose reflectance is low, the reflectance increases rapidly when the incident angle exceeds 80 °, and the laser beam cannot be used effectively. Therefore, the lower limit value of the laser beam incident angle is 80 °.
From these viewpoints, the incident angle of the laser beam is preferably in the range of 30 ° or more and 80 ° or less with respect to a perpendicular line standing on the upper surface 4a of the light emitting unit 4. In particular, the range of 40 ° or more and 70 ° or less is more preferable because surface reflection in the light emitting unit 4 can be further reduced while further reducing the influence of providing the window 6 on the parabolic mirror 5. Moreover, in the range of 60 ° or more and 65 ° or less, the incident angle of the laser beam is a Brewster angle, which is more preferable because the reflectance can be significantly reduced.
(When the laser beam path has a width)
As shown in FIG. 8B, when the optical path of the laser beam has a width and the width changes according to the distance from the light source, strictly speaking, the incident angle of the laser beam is one. Not determined. As described above, the lower limit value of the incident angle of the laser beam is 30 ° or more in order not to form the window portion 6 within an angle range of ± 30 ° from the perpendicular standing at the center of the upper surface 4a of the light emitting portion 4. Is preferred. From this viewpoint, when the laser light is irradiated from the apex side of the parabolic mirror 5, the angle of the line segment closest to the opening 5b of the parabolic mirror 5 among the line segments included in the outer edge of the laser optical path (FIG. 8B). It is preferable that the angle of the outer edge indicated by θ in FIG.
When the laser light is irradiated from the opening 5b side of the parabolic mirror 5, the angle of the line segment closest to the apex of the parabolic mirror 5 among the line segments included in the outer edge of the laser optical path is 30 ° or more. Preferably there is.
On the other hand, when the incident angle is captured from the viewpoint of suppressing reflection on the surface of the light emitting unit 4, it is preferable to consider the angle of the central axis of the laser light path, which is the average incident angle of one laser light path. . Therefore, the angle of the central axis of the laser light path is preferably 80 ° or less.
As for the Brewster angle at which surface reflection is minimized, it is preferable to set the angle of the central axis of the laser optical path to the Brewster angle (60 ° or more and 65 ° or less).
Even if the laser beam path has a width, when the laser beam is parallel light, the incident angle is determined to be one, so that the discussion can be made almost the same as when the laser beam path is considered to have no width.
FIG. 12 is a conceptual diagram showing the light projection characteristics of the parabolic mirror 5. As shown in FIG. 12, when the headlamp 1 is arranged with the metal base 7 facing downward, most of the fluorescence (indicated by reference numeral 30) that cannot be controlled by the parabolic mirror 5 is emitted upward. The inventors of the present invention have found that almost no light is emitted in the direction.
FIG. 13 is a diagram for explaining the principle of the light projection characteristics of the parabolic mirror 5. As shown in FIG. 13, the fluorescence (indicated by reference numeral 31) emitted from the upper surface of the light emitting unit 4 and reflected by the parabolic mirror 5 is emitted forward within a predetermined solid angle.
On the other hand, a part of the fluorescence (indicated by reference numeral 30) emitted from the side surface of the light emitting unit 4 is emitted from the predetermined solid angle and obliquely upward without hitting the parabolic mirror 5. Further, the fluorescence emitted in parallel to the surface of the metal base 7 from the side surface of the light emitting unit 4 is emitted as parallel light to the front. Therefore, the fluorescence that cannot be controlled by the parabolic mirror 5 is hardly emitted downward in the headlamp 1. If this light projecting characteristic is used, the parabolic mirror 5 side of the headlamp 1 can be appropriately illuminated using fluorescence that cannot be controlled by the parabolic mirror 5.
FIG. 14 is a conceptual diagram showing the arrangement direction of the headlamp 1 when the headlamp 1 is applied to an automobile (vehicle) 10. As shown in FIG. 14, the headlamp 1 is preferably disposed on the head of the automobile 10 so that the parabolic mirror 5 is positioned vertically downward. In this arrangement method, the front side of the automobile 10 can be illuminated brightly and the front lower side of the automobile 10 can be illuminated moderately brightly due to the projection characteristics of the parabolic mirror 5 described above.
Thus, the vehicle of this invention is a vehicle provided with the vehicle headlamp. The vehicle headlamp includes an excitation light source that emits excitation light, a light emitting unit that emits fluorescence in response to the excitation light emitted from the excitation light source, and a reflection curved surface that reflects the fluorescence generated by the light emission unit. And a support member (metal base 7) for supporting the light-emitting part. A part of the reflecting mirror is disposed above an upper surface of the light emitting unit having a larger area than a side surface, and the light emitting unit is thin, or the spot of the excitation light irradiated on the surface of the light emitting unit. The area is smaller than the area of the surface. The vehicle headlamp is disposed in the vehicle such that the reflection curved surface is positioned vertically downward. Further, the incident angle of the excitation light with respect to the upper surface is set so that the utilization efficiency of the fluorescence emitted from the light emitting unit is increased.
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).
FIG. 15 is a schematic view showing a headlamp 21 according to an embodiment of the present invention. As shown in FIG. 15, the headlamp 21 includes a set of a plurality of laser elements 2 and a condenser lens 11, a plurality of optical fibers (light guide members) 12, a magnifying lens 13, a reflection mirror 14, a light emitting unit 4, and a parabolic mirror. 5, a metal base 7 and fins 8 are provided.
The optical fiber 12 is a light guide member that guides the laser light oscillated by the laser element 2 to the light emitting unit 4. The optical fiber 12 has a two-layer structure in which the core of the core is covered with a clad having a refractive index lower than that of the core. Laser light incident from the incident end passes through the optical fiber 12 and The light is emitted from the emission end which is the end of the. The exit end of the optical fiber 12 is bundled with a ferrule or the like.
Laser light emitted from the exit from the exit end of the optical fiber 12 is magnified by the magnifying lens 13 (convex lens) so that the entire light emitting unit 4 having an upper surface with a diameter of 2 mm is irradiated. The expanded laser light is reflected by the reflecting mirror 14 to change the optical path, and is guided to the light emitting unit 4 through the window 6 of the parabolic mirror 5. At this time, the position and angle of the reflection mirror 14 are set so that the laser beam is irradiated at an angle of 45 ° with respect to the upper surface 4a of the light emitting unit 4.
The laser element 2 has a 1 W output for emitting 405 nm laser light, and a total of eight laser elements are provided. Therefore, the total output of the laser beam is 8W. Among the components of the laser light, the setting is made so that the P-polarized light is irradiated on the surface of the light emitting unit 4.
The shape of the light emitting unit 4 is, for example, a disk shape having a diameter of 2 mm and a thickness of 0.2 mm.
The metal base 7 is made of copper, and aluminum is vapor-deposited on the surface on the side where the light emitting unit 4 is disposed. On the back side, fins 8 having a length of 15 mm and a width of 1 mm are provided at intervals of 5 mm. Note that the metal base 7 and the fins 8 may be integrally formed.
(Effect of headlamp 21)
In the headlamp 21, since the light emitting unit 4 is thin and the upper surface of the light emitting unit 4 faces the reflection curved surface of the parabolic mirror 5, most of the fluorescence emitted from the light emitting unit 4 can be controlled by the parabolic mirror 5. As a result, the fluorescence that cannot be controlled by the parabolic mirror 5 can be reduced, and the utilization efficiency of the fluorescence can be increased.
Furthermore, since the incident angle of the laser beam with respect to the upper surface 4a of the light emitting portion 4 is 45 °, the window portion 6 can be formed outside the region of the reflection curved surface of the parabolic mirror 5 that receives about 50% of the fluorescence. As a result, the utilization efficiency of the fluorescence emitted from the light emitting unit 4 can be increased. Further, since the incident angle of the laser beam is 45 °, the surface reflection of the laser beam on the upper surface 4a of the light emitting unit 4 can be suppressed.
Therefore, the headlamp 21 can realize efficient light projection with little loss of fluorescence.
FIG. 16 is a schematic view showing a headlamp 22 according to another embodiment of the present invention. As shown in FIG. 16, the headlamp 22 includes a plurality of laser elements 2 and a condenser lens 11, a plurality of optical fibers 12, a magnifying lens 13, a reflecting mirror 14, a light emitting unit 4, a parabolic mirror 5, and a metal base 7. , Fins 8 and fans 15 are provided.
In the headlamp 22, the position and angle of the reflection mirror 14 are set so that the laser light is irradiated at an angle of 63 ° with respect to the upper surface 4 a of the light emitting unit 4.
One of the structural differences from the first embodiment is that a fan 15 is provided below the fin 8. Wind is sent to the metal base 7 and the fins 8 by the fan 15, and the heat dissipation effect by the metal base 7 and the fins 8 is enhanced. The metal base 7 and the fins 8 are the same as in the first embodiment.
The laser element 2 emits 450 nm laser light and has 1 W output, and a total of six laser elements are provided. Therefore, the total output of the laser beam is 6W. Of the components of the laser light, the P-polarized light with less surface reflection is set so as to irradiate the surface of the light emitting unit 4.
The opening 5b of the parabolic mirror 5 is a semicircle having a radius of 50 mm, and the depth of the parabolic mirror 5 is 45 mm. The light emitting unit 4 is disposed at the focal position of the parabolic mirror 5.
(Special effects of the headlamp 22)
In the headlamp 22, the laser beam is irradiated at an angle of 63 ° with respect to the upper surface 4 a of the light emitting unit 4. Since this angle is near the Brewster angle, it is possible to effectively suppress the surface reflection of the laser light on the upper surface 4a of the light emitting unit 4.
FIG. 17 is a schematic view showing a headlamp 23 according to another embodiment of the present invention. As shown in FIG. 17, the headlamp 23 includes a set of a plurality of laser elements 2 and a magnifying lens 3, a light emitting unit 4, a parabolic mirror 5, a metal base 7, and a water cooling pipe (cooling unit) 16.
The headlamp 23 is provided with 8 (total 8 W) eight 1 W output laser elements 2 that emit 450 nm laser light. In these laser elements 2, three, two, and three rows of laser elements 2 are arranged closest in three stages in the vertical direction (the z-axis direction in FIG. 18). FIG. 18 is a top view showing the arrangement of the plurality of laser elements 2.
The laser light emitted from the laser elements 2 packed in three stages is magnified by the magnifying lens 3 so as to be a spot having a diameter of 2 mm on the upper surface 4a of the light emitting unit 4.
The parabolic mirror 5 is formed with a window 6 that transmits laser light having an incident angle of 30 ° to 70 °. The laser light emitted from the eight laser elements 2 is transmitted through the window 6. The light emitting unit 4 is irradiated. The incident angle of each laser beam with respect to the upper surface 4a of the light emitting unit 4 is within a range of 30 ° to 70 °.
Therefore, the window portion 6 can be formed outside the region of the reflection curved surface of the parabolic mirror 5 that receives about 50% of the fluorescence. As a result, the utilization efficiency of the fluorescence emitted from the light emitting unit 4 can be increased.
One of the differences between the light emitting unit 4 and the first embodiment is that the area of the upper surface 4a (laser light irradiation surface) of the light emitting unit 4 is larger than the area of the laser light spot. The shape of the light emitting unit 4 is a disk shape having a diameter of 10 mm and a thickness of 0.1 mm. The same three types of phosphor powders as in Example 1 were uniformly mixed and applied to the resin. The light emitting unit 4 is irradiated with laser light as a circular spot having a diameter of 2 mm. The irradiation position of the laser beam is approximately the focal position of the parabolic mirror 5 and is approximately the center of the upper surface 4 a of the light emitting unit 4.
FIG. 19 is a schematic view showing a headlamp 24 according to another embodiment of the present invention. The headlamp 24 includes an array laser 41, a light guide unit 42, a light emitting unit 4, a parabolic mirror 5, a metal base 7, and fins 8.
The array laser 41 is a multi-emitter laser array in which 10 emitters are built in one package, and the total output is 8W. As a laser light source having a similar function, an array laser having a plurality of laser elements and emitting laser light from each laser element may be used. Of the components of the laser light, the P-polarized light with less surface reflection is set so as to irradiate the surface of the light emitting unit 4. The array laser 41 is disposed in the vicinity of the incident surface 42 a of the light guide unit 42.
The light guide unit 42 is a wedge-shaped (pyramidal or truncated pyramid) light guide member that guides to the light emitting unit 4 while collecting a plurality of laser beams oscillated by the array laser 41. The light guide unit 42 is made of, for example, quartz (SiO 2 ), and the laser light incident on the light guide unit 42 is totally reflected on the inner side surface of the light guide unit 42.
The light guide unit 42 is arranged such that the parabolic mirror 5 is disposed outside the incident surface 42 a that is one end surface of the light guide unit 42, and the emission surface 42 b that is the other end unit is disposed in the vicinity of the light emitting unit 4. The parabolic mirror 5 is disposed through the window 6 (opening).
Laser light emitted from the array laser 41 enters the light guide 42 from the light incident surface 42 a of the light guide 42. The incident laser light is guided while being totally reflected inside the light guide portion 42, and is emitted from the exit surface 42 b of the light guide portion 42.
Since the cross-sectional area of the exit surface 42b is smaller than the area of the entrance surface 42a (that is, the light guide portion 42 has a tapered structure), the laser light entering the light guide portion 42 is emitted from the exit surface 42b. It is condensed in the process of heading to.
The light emitting unit 4 is disposed in the vicinity of the emission surface 42 b of the light guide unit 42, and the laser light emitted from the emission surface 42 b is irradiated as a spot having a diameter of 2 mm on the substantially upper surface of the light emitting unit 4.
As described above, the window portion 6 is preferably formed outside a range of ± 30 ° with a perpendicular line standing on the upper surface 4a of the light emitting portion 4 as a reference axis. Therefore, the angle formed by the side surface 42c of the light guide 42 on the opening 5b side of the parabolic mirror 5 and the reference axis is set to be larger than 30 °.
Further, in order to prevent the laser light emitted from the emission surface 42b from being reflected on the surface of the light emitting unit 4, the central axis 42d (perpendicular to the center of the incident surface 42a) 42d of the light guide unit 42 and the reference axis The angle formed by is set to 80 ° or less. The angle is, for example, 45 °.
The light emitting unit 4 has a disk shape with a diameter of 2 mm and a thickness of 0.2 mm. The composition of the light emitting part 4 is the same as that of Example 1, and the phosphor powder is sintered and hardened.
The metal base 7 and the fins 8 are the same as in the first embodiment.
(Special effects of the headlamp 24)
Since the headlamp 24 uses the light guide section 42, it is easy to collect a plurality of laser beams from the array laser 41 and irradiate the light emitting section 4 at a desired angle. Further, since the window portion 6 for inserting the light guide portion 42 is formed outside the reflection curved surface region of the parabolic mirror 5 that receives about 50% of the fluorescence, it is possible to realize efficient light projection with little loss of fluorescence.
FIG. 20 is a schematic view showing a headlamp 25 according to another embodiment of the present invention. As shown in FIG. 20, the headlamp 25 includes a set of a plurality of laser elements 2 and a condenser lens 11, a plurality of optical fibers 12, a light emitting unit 4, a parabolic mirror 5, a metal base 7, and fins 8.
The optical fiber 12 is a light guide member that guides the excitation light emitted from the laser element 2 to the light emitting unit 4. The position of the emission end 12a is fixed so that the laser beam emitted from the emission end 12a of the optical fiber 12 is irradiated onto the upper surface of the light emitting unit 4 at an angle of 30 °. In FIG. 20, the optical fiber 12 passes through the vicinity of the apex of the parabolic mirror 5, but an opening may be provided in the metal base 7, and the optical fiber 12 may be guided into the parabolic mirror 5 from the opening.
Since the optical fiber 12 has flexibility, it is possible to easily set the incident angle and the incident direction of the laser light.
FIG. 21 is a schematic diagram showing an illumination device 26 according to an embodiment of the present invention. As shown in FIG. 21, the illumination device 26 includes a set of a plurality of laser elements 2 and a condenser lens 11, a plurality of optical fibers 12, a magnifying lens 13, a reflecting mirror 14, a light emitting unit 4, and an elliptical mirror (reflecting mirror) 51. , A metal base 7, a fin 8 and a rod lens 43.
The position of the window 51a and the position and angle of the reflection mirror 14 are set so that the laser light reflected by the reflection mirror 14 is irradiated through the window 51a to the upper surface of the light emitting unit 4 at an angle of 60 °. ing.
The biggest difference from the first embodiment is that in the illumination device 26, the reflecting mirror is not a parabolic mirror but an elliptical mirror (elliptical spherical mirror). The light emitting unit 4 is disposed at the first focal position of the elliptical mirror 51. The fluorescence reflected by the elliptical mirror 51 enters an incident surface 43a formed at one end of the rod lens 43, guides the inside of the rod lens 43, and an output surface 43b formed at the other end. It is emitted from. The incident surface 43 a is disposed at the second focal position of the elliptical mirror 51.
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. For example, like the headlamp 27 shown in FIG. 22, the front side and the back side of a metal plate (thermally conductive member, support member) 71 that passes through the vicinity of the apex of the parabolic mirror (reflecting mirror) 52 and extends into the parabolic mirror 52. The light emitting unit 4 may be disposed on the surface. The metal plate 71 is a silver-plated copper plate, and the light emitting unit 4 is disposed at a substantially focal position of the parabolic mirror 52.
Laser light oscillated from the laser element 2 is shaped into parallel light by the lens 18, and is narrowed down to the size of the upper surface of the light emitting unit 4 by the condenser lens 19. Thereafter, the laser light is reflected by the reflection mirror 14 and is applied to the light emitting unit 4 through the window 52 a of the parabolic mirror 52.
4 Light emitting part 4a Upper surface 4c Spot 5 Parabolic mirror (reflecting mirror)
8 Fin (cooling part)
10 Automobile (vehicle)
15 Fan (cooling part)
26 Lighting device (light emitting device)
42 Light Guide 51 Elliptical Mirror (Reflector)
51a Window 52 Parabolic mirror (reflector)
51a Window portion 71 Metal plate (thermally conductive member, support member)
A light projecting unit for projecting the fluorescence generated by the light emitting unit,
The distribution of fluorescence emitted from the light emitting part is a Lambertian distribution,
And the incident angle of the excitation light with respect to the excitation light irradiation surface, which is the surface of the light emission unit irradiated with the excitation light, is set so that the utilization efficiency of the fluorescence emitted from the light emission unit is increased,
The excitation light is P-polarized with respect to the excitation light irradiation surface,
The incident angle is in a range of 60 ° or more and 65 ° or less with respect to a perpendicular line formed on the excitation light irradiation surface,
The thickness of the light emitting portion is not more than one-tenth of the maximum width when the light emitting portion is viewed from a direction perpendicular to the thickness direction,
The light projecting portion includes a reflecting mirror, and the reflecting mirror is a portion obtained by cutting a curved surface formed by rotating a parabola around the axis of symmetry of the parabola as a plane including the rotating axis. Including at least part of the curved surface,
A part of the side surface of the light emitting unit when the excitation light irradiation surface is an upper surface faces the direction of the opening of the reflecting mirror.
In the light emitting unit, the excitation light irradiation surface that is the surface that receives the excitation light and the surface that mainly emits the fluorescence are the same,
The excitation light irradiation surface is a plane,
An incident angle of the excitation light with respect to the excitation light irradiation surface is in a range of 30 ° or more and 80 ° or less with respect to a perpendicular line formed on the excitation light irradiation surface .
The area of the spot of the excitation light irradiated on the excitation light irradiation surface is smaller than the area of the excitation light irradiation surface,
4. The light emitting device according to claim 2 , wherein the incident angle is in a range of 40 ° or more and 70 ° or less with respect to a perpendicular line formed on the excitation light irradiation surface.
The light-emitting device according to claim 2, wherein the excitation light is P-polarized light with respect to the excitation light irradiation surface.
6. The light emitting device according to claim 2, wherein the incident angle is in a range of 60 ° or more and 65 ° or less with respect to a perpendicular line formed on the excitation light irradiation surface.
The light projecting portion includes a reflecting mirror, and the reflecting mirror is a portion obtained by cutting a curved surface formed by rotating a parabola around the axis of symmetry of the parabola as a plane including the rotating axis. the light emitting device according to any one of claims 2-6, characterized in that it contains at least a portion of the curved surface.
The light emitting unit, the light emitting device according to any one of claims 1 to 7, characterized in that it is supported by a thermally conductive member.
The excitation light source is disposed outside the light projecting unit,
The light emitting device according to any one of claims 1 to 8 , wherein a window portion through which the excitation light is transmitted or passed is provided in the light projecting portion.
The light emitting device according to any one of claims 1 to 9 , further comprising a magnifying lens that expands an irradiation range of the excitation light and irradiates the light emitting unit.
The light-emitting device according to claim 9 , wherein a light guide unit that condenses the excitation light emitted from the excitation light source and guides the excitation light to the light-emitting unit is disposed through the window unit.
The light emitting device according to any one of claims 1 to 8, characterized in that the excitation light emitted from the excitation light source is an optical fiber leading to the light emitting portion is arranged.
Vehicle headlamp, characterized in that it comprises a light-emitting device according to any one of claims 1 to 12.
Lighting apparatus comprising a light-emitting device according to any one of claims 1 to 12.
JP2010244570A 2010-10-29 2010-10-29 Light emitting device, vehicle headlamp and lighting device Active JP5487077B2 (en)
JP2010244570A JP5487077B2 (en) 2010-10-29 2010-10-29 Light emitting device, vehicle headlamp and lighting device
CN 201110328955 CN102537806B (en) 2010-10-29 2011-10-26 Light emitting device, vehicle headlamp, and illumination device
CN201510088672.7A CN104608681B (en) 2010-10-29 2011-10-26 Light-emitting device, headlight for automobile and lighting device
US13/284,487 US8814405B2 (en) 2010-10-29 2011-10-28 Light emitting device, vehicle headlamp, and illumination device
JP2012099280A JP2012099280A (en) 2012-05-24
JP5487077B2 true JP5487077B2 (en) 2014-05-07
ID=45996596
JP2010244570A Active JP5487077B2 (en) 2010-10-29 2010-10-29 Light emitting device, vehicle headlamp and lighting device
US (1) US8814405B2 (en)
JP (1) JP5487077B2 (en)
CN (2) CN102537806B (en)
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2011-10-26 CN CN 201110328955 patent/CN102537806B/en active IP Right Grant
2011-10-26 CN CN201510088672.7A patent/CN104608681B/en active IP Right Grant
2011-10-28 US US13/284,487 patent/US8814405B2/en active Active
JP2012099280A (en) 2012-05-24
CN104608681B (en) 2017-07-21
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CN102537806B (en) 2015-04-01
US8814405B2 (en) 2014-08-26
CN104608681A (en) 2015-05-13
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