WO2016027373A1

WO2016027373A1 - Light source apparatus, vehicle lamp, and chromacity adjustment method for light source apparatus

Info

Publication number: WO2016027373A1
Application number: PCT/JP2014/072016
Authority: WO
Inventors: 康彦國井
Original assignee: 日立マクセル株式会社
Priority date: 2014-08-22
Filing date: 2014-08-22
Publication date: 2016-02-25

Abstract

The purpose of the present invention is to adjust the chromaticity of illumination light without causing a decrease in output from a light-emitting element according to the surrounding environment, in a light source apparatus or a vehicle lamp which uses the semiconductor light-emitting element as a source for excitation light. For that purpose, the light source apparatus has: a semiconductor light-emitting element emitting excitation light; a movable stage on which the semiconductor light-emitting element is mounted; a phosphor emitting fluorescent light by the excitation light emitted from the semiconductor light-emitting element; and a control unit for controlling the movement of the movable stage. The control unit controls the incident angle of light from the semiconductor light-emitting element with respect to the phosphor, and arbitrarily controls the mixing ratio of the fluorescent light emitted from the phosphor and the excitation light to the light reflected by the phosphor, thereby arbitrarily controlling the chromaticity of illumination light.

Description

LIGHT SOURCE DEVICE, VEHICLE LIGHT, AND Chromaticity Adjustment Method for Light Source Device

The present invention relates to a light source device using a semiconductor light emitting element, a vehicular lamp, and a chromaticity adjustment method for the light source device.

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

For example, Japanese Patent Laid-Open No. 2012-99281 (Patent Document 1) discloses an excitation light source that emits excitation light having an oscillation wavelength in a blue-violet region, and a light emitting unit that emits light by receiving excitation light emitted from the excitation light source. And an illumination device that increases the color temperature by using excitation light from an excitation light source as illumination light is described.

In JP2013-161889A (Patent Document 2), two types of phosphors are used as a technique for adjusting the color of illumination light, and the first phosphor is changed by changing the wavelength of excitation light. Describes a light emitting device that changes the ratio of fluorescent light generated from the fluorescent light generated from the second fluorescent material.

JP 2012-99281 A JP 2013-161889 A

The human eye changes its sensitivity to wavelengths in photopic and scotopic vision due to Purkinje's phenomenon, and the peak of sensitivity changes to the short wavelength side in the dark. Therefore, the chromaticity of the illumination light is adjusted according to the surrounding environment. It is desirable to do.

However, Patent Document 1 and Patent Document 2 do not consider changing chromaticity positively according to the surrounding environment. Patent Document 2 describes a technique for adjusting color by adjusting the temperature of a light emitting element. However, an increase in the temperature of the light emitting element causes a decrease in output of the light emitting element, and a wavelength change with respect to temperature is small. There is a problem.

An object of the present invention is to adjust the chromaticity of illumination light in a light source device or a vehicle lamp using a semiconductor light emitting element as excitation light, without causing a decrease in output of the light emitting element, depending on the surrounding environment.

In order to solve the above problems, for example, the configuration described in the claims is adopted. The present invention includes a plurality of means for solving the above-described problems. For example, a light source device, which is a semiconductor light emitting device that emits excitation light, a movable stage on which the semiconductor light emitting device is mounted, and a semiconductor A phosphor that emits fluorescent light by excitation light emitted from the light emitting element and a control device that controls the movement of the movable stage, the control device controls the incident angle of the excitation light to the phosphor of the semiconductor light emitting element, The fluorescent light emitted from the fluorescent material and the reflected light of the excitation light from the fluorescent material are mixed to form illumination light.

According to the present invention, the color of the illumination light can be controlled by arbitrarily controlling the mixing ratio of the reflected light component of the excitation light on the phosphor surface and the fluorescence light emitted by the excitation light according to the incident angle of the excitation light to the phosphor. The degree can be controlled arbitrarily.

It is a figure which shows the structure of the optical system of the vehicle lamp in Example 1. FIG. It is a spectrum of the light emitted from the phosphor when the phosphor is irradiated with the excitation light in Example 1. It is a figure which shows the change of the diffuse excitation light by the excitation light incident angle in Example 1, and fluorescence light. FIG. 3 is a diagram illustrating a change in white chromaticity depending on an incident angle of excitation light in Example 1. It is an apparatus block diagram of the vehicle lamp in Example 1. FIG. FIG. 5 is a diagram illustrating a configuration of a phosphor in Example 2. It is the figure which showed the transmittance | permeability change with respect to the thickness of the fluorescent substance film in Example 2. FIG. It is a figure showing the refraction angle and passage distance in the fluorescent substance film by the incident angle of the fluorescent substance in Example 2. It is a schematic diagram explaining the refraction angle and passage distance in a fluorescent substance film by the incident angle of the fluorescent substance in Example 2. FIG. 6 is a diagram illustrating a change in white chromaticity in Example 2. FIG. FIG. 6 is a diagram illustrating a configuration of an optical system of a vehicular lamp according to a third embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a configuration of an optical system of a vehicular lamp in the present embodiment. The optical system of the vehicular lamp is a so-called projector-type lamp, and includes a semiconductor light emitting element 11, a condenser lens 12, a phosphor 13, a metal plate 14, a reflector 15, and a movable stage 300. A laser diode (LD) is used for the semiconductor light emitting element 11 serving as a light source, and emits blue laser light as excitation light of the phosphor 13. The condenser lens 12 is disposed on the emission side of the semiconductor light emitting element 11 and condenses the excitation light (blue laser light) 100 emitted from the semiconductor light emitting element 11 on the surface of the phosphor 13.

The phosphor 13 is formed in a partial region on the metal plate 14. The phosphor 13 is a fluorescent material that emits yellow light when excited by the excitation light 100 emitted from the semiconductor light emitting element 11, and a scattering agent having a different refractive index is mixed therein to scatter incident light. Or let me. Therefore, when the phosphor 13 receives the excitation light 100, the phosphor 13 generates fluorescent light (yellow light), and the excitation light (blue light) scattered by the phosphor 13 is mixed. As a result, white light 200 is emitted from the phosphor 13. Is done. As a result, the phosphor 13 emits white light like a point light source having substantially the same size as the condensing spot of the excitation light. In addition, the semiconductor light emitting element 11 is installed so that the excitation light 100 is incident on the phosphor 13 as p-polarized light. Thereby, the reflectance can be reduced by the relationship between the incident angle and the reflectance, and the absorption in the phosphor can be increased.

The metal plate 14 holds the phosphor 13 and has a mirror surface on the surface, so that the white light generated from the phosphor 13 is reflected to the reflector 15 side.

The reflector 15 is formed in a curved plate shape that opens to face the phosphor 13 and is disposed so as to face the phosphor 13. One surface of the reflector 15 is a reflecting surface 15a that reflects the white light emitted from the phosphor 13 to one side. The reflection surface 15a is formed in a free-form surface shape, for example, a shape based on a paraboloid, so as to obtain a desired light distribution. The reflecting surface 15a is disposed so as to face the phosphor 13 so as to face the phosphor 13. The white light emitted from the phosphor 13 is irradiated, for example, in front of the vehicle on which the vehicle lamp is installed. Let

FIG. 2 shows an example of a spectral spectrum of light emitted from the phosphor 13 when the phosphor 13 is irradiated with the excitation light 100. A blue semiconductor laser having a wavelength of 440 nm is used as the excitation light, and the phosphor is a YAG phosphor ((Y, Gd) 3 (Al, Ga) that emits yellow light having a complementary color relationship with blue light with high efficiency. O12: Ce3 +) is used. In FIG. 2, the peak appearing in the vicinity of 440 nm is a diffuse excitation light component, and the broad peak appearing at a wavelength of 440 nm or more is yellow fluorescent light. The ratio of the two light emitting components determines the chromaticity of the generated white light. Here, the excitation light and the phosphor are not limited to this, and any combination that produces white light may be used. For example, blue and red phosphors may be used for the blue laser.

FIG. 3 is an example showing changes in diffuse excitation light and fluorescent light depending on the excitation light incident angle. Assuming that the angle of the excitation light (blue laser light) 100 with respect to the normal of the plane of the phosphor 13 in FIG. 1 is the laser light incident angle θ, as shown in FIG. 3, the excitation diffused light increases as the laser light incident angle θ increases. Increases, while the fluorescent light emitted from the phosphor decreases. This is because the ratio of the excitation light reflected by the phosphor film increases as the laser beam incident angle θ increases, resulting in a decrease in the energy of the excitation light transmitted to the phosphor and a decrease in the output of the fluorescence light. . Therefore, when the ratio of the fluorescence light and the diffusion excitation light changes depending on the incident angle, the chromaticity of the white light generated by the fluorescence light and the diffusion excitation light also changes.

FIG. 4 is an example showing white chromaticity change depending on the incident angle of excitation light. As shown in FIG. 4, the chromaticity of the white light generated on the straight line connecting the chromaticities of the fluorescent light and the diffuse excitation light is shifted according to the ratio of the fluorescent light and the diffusion excitation light depending on the incident angle. In FIG. 4, the chromaticity on the black body radiation line can be realized when the incident angle of the excitation light is around 60 degrees, and the color temperature which is the chromaticity of the white light by changing the incident angle of the excitation light. Can be controlled to be higher or lower.

FIG. 5 shows an apparatus block diagram of the vehicular lamp according to the present embodiment. A sensor unit 400 measures the ambient environment of the vehicular lamp and senses, for example, whether it is a bright place at daytime or a dark place at night. Based on the detection signal of the sensor unit 400, the calculation unit 500 calculates, for example, the chromaticity of the illumination light corresponding to the sensitivity to the wavelengths in the photopic and scotopic vision of the human eye, and corresponds to the chromaticity. The incident angle of the excitation light is calculated from, for example, white chromaticity change characteristics according to the incident angle of the excitation light shown in FIG. 4 measured in advance. Next, the angle controller 600 drives the excitation light source gonio stage 700 according to the calculated incident angle to irradiate the phosphor with excitation light at a desired incident angle. Here, the gonio stage is a moving stage that moves in an arc around a point on the normal line from the center of the stage, and corresponds to the movable stage 300 shown in FIG. That is, as a control device that controls the movement of the movable stage, it has a sensor unit, a calculation unit, and an angle control unit. The sensor unit measures the brightness of the surrounding environment, and the calculation unit uses the measurement results to Calculate the chromaticity of the illumination light according to the environment, calculate the incident angle of the excitation light corresponding to the chromaticity, drive the movable stage according to the incident angle calculated by the angle control unit, and at the desired incident angle The phosphor is irradiated with excitation light.

In this embodiment, the vehicular lamp has been described. However, the present invention is not limited to this, and for example, the present invention can be applied to a light source device having a configuration excluding the reflector 15 in FIG.

As described above, according to the present embodiment, the mixing ratio of the reflected light component of the excitation light on the phosphor surface and the fluorescence light emitted by the excitation light is controlled by controlling the incident angle of the excitation light to the phosphor. Thus, it is possible to arbitrarily control the chromaticity of the illumination light without causing a decrease in the output of the light emitting element.

FIG. 6 is a structural example of the phosphor in this embodiment. In this embodiment, the phosphor film is divided into two layers in the thickness direction using two different phosphors, and the first-layer phosphor 13a and the second-layer phosphor 13b are formed on the metal plate. When excitation light enters the phosphor film, the intensity of the excitation light attenuates as it proceeds in the depth direction. The amount of attenuation is expressed by the following equation (1) according to Lambert-Beer's law that formulates the absorption of light through the substance, and the amount of light I after passing with respect to the amount of light before incidence I ₀ . Here, α is an absorption coefficient, and d is a passing distance.

FIG. 7 is an example of fitting the transmittance depending on the thickness of the phosphor film from the experimental results, and the 400 nm excitation light attenuates with an absorption coefficient α = 0.027. For this reason, in the phosphor film having a two-layer structure as shown in FIG. 6, the longer the first layer passes, the more the excitation light does not reach the second layer, so the proportion of the second layer that contributes to light emission decreases. .

FIG. 8 is an example showing the refraction angle and the passing distance in the phosphor film according to the incident angle of the phosphor. When the incident angle is θi, the refraction angle is θr, the refractive index n1 of air and the refractive index n2 of the phosphor are expressed by the following relational expression (2).

Here, since the refractive index n1 of air is 1 and the refractive index n2 of the YAG phosphor is 1.83, the refraction angle θr is smaller than the incident angle θi. Further, the light passing distance in the material changes due to the change in the refraction angle depending on the incident angle of the light and the refractive index of the material, and FIG. 8 shows the phosphor of the light beam up to about 1.2 times the film thickness depending on the incident angle of the light. It shows that the membrane passage distance becomes longer.

FIG. 9 shows a schematic diagram for explaining the result. When the excitation light incident angle θi in FIG. 9A is small, the refraction angle θr is also small, so the distance d1 that passes through the first-layer phosphor 13a is shortened, and the emission ratio from the second-layer phosphor 13b is reduced. Increase. On the other hand, as shown in FIG. 9B, when the incident angle θi ′ is large, the refraction angle θr ′ is also large, so the distance d1 ′ that passes through the first-layer phosphor 13a is long and the excitation light is 1 The amount absorbed by the layer increases. As a result, the amount of light emitted from the second-layer phosphor 13b is reduced. Therefore, when the first layer phosphor 13a is composed of a yellow phosphor and the second layer phosphor 13b is a red phosphor, when the incident angle of the excitation light is large, the blue light of the excitation light and the first layer phosphor 13a In addition to the above-described blue light and yellow light, when the incident angle of the excitation light is small, the color temperature obtained by adding the red light from the second-layer phosphor 13b is realized. Low white light can be realized.

FIG. 10 is a diagram showing a change in white chromaticity according to the present embodiment. In FIG. 10, the white chromaticity range required for the vehicular lamp is defined by the chromaticity standard indicated by the dotted line. In the case where the phosphor of Example 1 is a single layer, the chromaticity adjustment of white light only changes the ratio of the excitation light and the monochromatic fluorescent light, and thus changes linearly, and there are cases where it deviates from the chromaticity standard. . However, the white light chromaticity adjustment in this embodiment has the characteristics shown by the dotted line in FIG. 10 for the two layers of the phosphor. The phosphor is divided into two layers, the excitation light, the first layer of fluorescent light, and the two layers. Since the ratio of the three fluorescent lights of the eyes is changed, it is possible to adjust the chromaticity of the white light two-dimensionally. As a result, there is an effect that the chromaticity adjustment range of white light within the chromaticity standard can be increased. Note that the chromaticity change curve of arbitrary white light can be realized by using three layers or more layers of phosphors instead of two layers, but the penetration of excitation light into the layers decreases as the number of layers increases. Therefore, the contribution of the fluorescent light to the multilayering is small. Further, instead of changing the phosphor in the layer direction, the phosphor may be changed in the excitation light incident surface direction.

FIG. 11 is a diagram showing a configuration of an optical system of the vehicular lamp according to the present embodiment. Each component in the present embodiment is denoted by the same reference numeral as that in FIG. 1 of the first embodiment, and has the same function, and thus the description thereof is omitted. The difference from FIG. 1 is the direction in which the excitation light (blue laser light) 100 emitted from the semiconductor light emitting element 11 is condensed on the surface of the phosphor 13. In other words, in FIG. 1, the semiconductor light emitting element 11 is arranged on the irradiation direction side of the white light emitted from the phosphor 13 by the reflecting surface 15a of the reflector 15 with respect to the phosphor. Then, as shown in FIG. 11, it arrange | positions in the direction opposite to the irradiation direction of white light. With this configuration, in FIG. 1, in order to avoid the irradiation light of the white light, it is necessary to dispose the semiconductor light emitting element 11 in the thickness direction, and thus it is necessary to increase the thickness of the device. However, in this embodiment, since it is not necessary to escape in the thickness direction, there is an effect that the apparatus can be thinly configured.

In addition, this invention is not limited to the above-mentioned Example, Various modifications are included. For example, the above-described embodiments are described in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

11: Semiconductor light emitting element, 12: Condensing lens, 13: Phosphor
13a: first layer phosphor, 13b: first layer phosphor, 14: metal plate, 15: reflector,
15a: reflecting surface, 100: excitation light, 200: white light, 300: movable stage,
400: sensor unit, 500: calculation unit, 600: angle control unit,
700: Excitation light source gonio stage

Claims

A semiconductor light emitting element that emits excitation light; and
A movable stage on which the semiconductor light emitting element is mounted;
A phosphor that emits fluorescent light by excitation light emitted from the semiconductor light emitting element;
A control device for controlling the movement of the movable stage;
The control device controls the incident angle of the excitation light to the phosphor of the semiconductor light emitting element, and mixes the fluorescence light emitted from the phosphor and the reflected light of the excitation light from the phosphor to generate illumination light. And a light source device.
The light source device according to claim 1,
The light source device, wherein the control device controls movement of the movable stage according to an ambient environment.
The light source device according to claim 1,
The control device includes a sensor unit, a calculation unit, and an angle control unit,
Measure the brightness of the surrounding environment with the sensor unit,
Calculate the chromaticity of the illumination light according to the surrounding environment based on the measurement result in the calculation unit, calculate the incident angle of the excitation light corresponding to the chromaticity,
A light source device characterized in that the angle control unit drives the movable stage according to the calculated incident angle to irradiate the phosphor with excitation light at a desired incident angle.
The light source device according to any one of claims 1 to 3,
The semiconductor light emitting element is a laser diode, and is installed so that incident light on the phosphor is incident in a p-polarized state.
The light source device according to any one of claims 1 to 4,
2. The light source device according to claim 1, wherein the phosphor is formed by laminating a plurality of types of phosphors.
A semiconductor light emitting element that emits excitation light; and
A movable stage on which the semiconductor light emitting element is mounted;
A phosphor that emits fluorescent light by excitation light emitted from the semiconductor light emitting element;
A reflector that receives and reflects the fluorescent light emitted from the phosphor and the reflected light from the phosphor of the excitation light, and emits illumination light;
A control device for controlling the movement of the movable stage;
The vehicular lamp characterized in that the control device controls an incident angle of excitation light to a phosphor of the semiconductor light emitting element.
The vehicular lamp according to claim 6,
The vehicle lamp according to claim 1, wherein the control device controls movement of the movable stage in accordance with an ambient environment.
The vehicular lamp according to claim 6,
The control device includes a sensor unit, a calculation unit, and an angle control unit,
Measure the brightness of the surrounding environment with the sensor unit,
Calculate the chromaticity of the illumination light according to the surrounding environment based on the measurement result in the calculation unit, calculate the incident angle of the excitation light corresponding to the chromaticity,
A vehicular lamp, wherein the angle control unit drives the movable stage according to the calculated incident angle to irradiate the phosphor with excitation light at a desired incident angle.
The vehicular lamp according to any one of claims 6 to 8,
The vehicular lamp, wherein the semiconductor light emitting element is a laser diode, and is installed so that incident light on the phosphor is incident in a p-polarized state.
The vehicular lamp according to any one of claims 6 to 9,
A vehicular lamp characterized in that the phosphor is composed of a plurality of types of phosphors formed in layers.
A semiconductor light-emitting element that emits excitation light; and a phosphor that emits fluorescent light by the excitation light emitted from the semiconductor light-emitting element, the fluorescent light emitted from the phosphor and the phosphor of the excitation light from the phosphor A method for adjusting the chromaticity of a light source device that mixes reflected light with illumination light to produce illumination light,
The color of the illumination light is controlled by controlling the incident angle of the excitation light to the phosphor of the semiconductor light emitting device to control the mixing ratio of the reflected light of the excitation light to the phosphor and the fluorescence light emitted by the excitation light. A chromaticity adjustment method for a light source device, wherein the chromaticity adjustment is performed.