JP2017228390A - Lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illuminating device capable of emitting illumination light with suppressed color unevenness. An illumination apparatus includes a light source, a wavelength conversion unit that is irradiated with light from the light source and generates light by reflection of the irradiated light, and the light source between the light source and the wavelength conversion unit. The at least one pair of openings 50a and 50b is disposed at a symmetrical position with respect to a vertical axis perpendicular to the reference plane of the wavelength conversion unit 30, and the light from the light source 10 has a wavelength through the pair of openings 50a and 50b. And a reflector 50 that irradiates the conversion unit 30 and reflects light emitted from the wavelength conversion unit 30 by a mirror provided on the back surface. [Selection] Figure 2

Description

  The present invention relates to an illumination device that combines a light source and a phosphor.

  In recent years, lighting devices that radiate laser light emitted from a laser diode onto a light emitting unit including a phosphor, and further reflect the fluorescence excited by the light emitting unit with a reflector and emit the light forward, have been widely used. Etc. are used.

  For example, in the light emitting device disclosed in Patent Document 1, laser light (blue light) emitted from a laser element is applied to a light emitting unit that emits fluorescence (yellow light) through a window portion of a parabolic mirror. That is, the phosphor is excited using laser light, and the fluorescence generated from the phosphor is used as the light component of the illumination light.

  Furthermore, the blue light component that has not contributed to the excitation of the phosphor is also scattered to be used as the light component of the illumination light, and the scattered blue light and the yellow light of the phosphor are mixed, thereby White light is obtained (paragraph 0031, FIG. 1).

Japanese Patent No. 5842041

  However, when laser light is incident on the light emitting unit at a predetermined incident angle as in Patent Document 1, reflected light (blue light) having the same angle as the incident angle is generated on the upper surface of the light emitting unit and projected onto the screen. May appear as uneven color.

  This invention is made | formed in view of such a situation, and it aims at providing the illuminating device which can radiate | emit the illumination light which suppressed the color nonuniformity.

  The illuminating device of the present invention includes a light source, a light emitting unit that emits light from the light source and emits light by reflection of the irradiated light, and is disposed between the light source and the light emitting unit, and includes at least a pair of openings. At a position symmetric with respect to a vertical axis perpendicular to the reference plane of the light emitting unit, and the light from the light source is irradiated to the light emitting unit through the pair of openings, and the light emitted from the light emitting unit is emitted. And a reflector that is reflected by a mirror provided on the back surface.

  In the illuminating device of the present invention, light (blue light) from the light source is irradiated to the light emitting unit, and light emission (yellow light) is generated by reflection. This emitted light is reflected by the mirror on the back of the reflector and constitutes illumination light.

  Light from the light source is incident from one of a pair of openings provided on the reflector and symmetrical with respect to a vertical axis perpendicular to the reference plane of the light emitting unit (light emitting surface of the light emitting unit). Reflected. Here, since the incident angle and the reflection angle coincide with each other, the specularly reflected light is emitted from the other of the pair of openings. For this reason, it can prevent that the light from a light source concentrates on a specific part, and color unevenness arises.

  In the present invention, the optical axis of the light source and the vertical axis of the light emitting unit intersect at a predetermined inclination angle in a predetermined direction, and the optical axis of the light source and the direction orthogonal to the predetermined direction intersect perpendicularly. It is preferable.

  According to this configuration, the optical axis of the light source and the vertical axis of the light emitting unit intersect at a predetermined inclination angle in a predetermined direction (for example, a horizontal direction when the illumination device is viewed from the front). Is incident in an oblique direction with respect to the reference plane of the light emitting portion and reflected.

  In addition, since the optical axis of the light source and the direction orthogonal to the predetermined direction (for example, the horizontal direction when the illumination device is viewed from the side) intersects perpendicularly, the light reflected by the reference plane is reliably paired. Released from the other side of the opening.

  Moreover, in this invention, it is preferable that the said predetermined inclination angle is an angle between 60 degrees-75 degrees with respect to the vertical axis | shaft of the said light emission part.

  When the inclination angle formed between the optical axis of the light source and the vertical axis of the light emitting unit is set to an angle between 60 ° and 75 °, the light from the light source has a beam diameter of a predetermined length / short ratio when irradiated on the light emitting unit. Become an oval. That is, since the light is wide in the lateral direction, a light distribution used for vehicle lighting or the like can be easily made.

  In the present invention, it is preferable that the light sources are at least a pair of light sources, and the pair of light sources are disposed at positions corresponding to the pair of openings.

  According to this configuration, by arranging the pair of light sources at positions corresponding to the pair of openings, respectively, when the light from each light source is irradiated on the light emitting unit, it is different from the opening through which the regularly reflected light is incident. , From the other opening. Thereby, it is possible to prevent light from each light source from concentrating on a specific portion and causing color unevenness.

  In the present invention, the light source is a blue laser diode, and the light emitting unit includes a phosphor that generates yellow fluorescence when irradiated with light of the blue laser diode. The blue light of the blue laser diode and the fluorescent yellow light are preferable.

  According to this configuration, the laser light emitted from the blue laser diode irradiates the phosphor of the light emitting unit, and the fluorescence is excited. The emitted light is laser light that is blue light and fluorescence that is yellow light, and white illumination light is obtained by combining these.

  The light source is an RGB laser diode, and the light emitting unit includes a light diffusing plate that diffuses light of the RGB laser diode, and the light emission is light diffused by the light diffusing plate. Also good.

  According to this configuration, the light sources are red, green, and blue RGB laser diodes, and the three colors of laser light are diffused by the light diffusion plate. The emitted light is light diffused by the light diffusing plate, and white illumination light is obtained by mixing the laser light.

  Moreover, in this invention, it is preferable to provide the optical fiber which guide | induces the light from the said light source to the said opening.

  According to this configuration, the light from the light source is guided to the opening using the optical fiber, so that the loss due to the propagation of the light can be reduced and the apparatus can be downsized.

Sectional drawing which shows the whole structure of the illuminating device which concerns on embodiment of this invention. Sectional drawing (front view) of the AA of the illuminating device of FIG. The graph which shows the relationship between the incident angle to the wavelength conversion part of a laser beam, and the length ratio of a beam diameter. The figure which shows the relationship between an incident angle, a beam diameter, and a length ratio. FIG. 6 is a diagram (1) for explaining overlapping of laser spots of light by a plurality of light sources. FIG. 2 is a diagram for explaining overlapping of laser spots of light by a plurality of light sources (2). FIG. 3 is a diagram (3) for explaining overlapping of laser spots of light by a plurality of light sources.

  FIG. 1 is a cross-sectional view showing the overall configuration of a lighting device 1 according to an embodiment of the present invention.

  The illumination device 1 includes a light source 10, a collimating lens 20, a wavelength conversion unit 30, a reflective substrate 40, a reflector 50, a condenser lens 60, and a mirror unit 70.

  As shown in FIG. 1, a collimating lens 20 is disposed between the light source 10 and the wavelength conversion unit 30. As a result, the light emitted from the light source 10 is converted into parallel light through the collimating lens 20 and is irradiated to the wavelength conversion unit 30. The wavelength conversion unit 30 converts the wavelength of light incident from the light source 10 to generate yellow light. The wavelength conversion unit 30 corresponds to the “light emitting unit” of the present invention.

  The light source 10 is disposed outside the reflector 50 whose inner surface (back surface) is a reflecting mirror, and the wavelength conversion unit 30 is disposed inside the reflector 50. The reflector 50 has a spheroid shape with the position where the wavelength conversion unit 30 is disposed approximately as a focal position.

  The yellow light generated in the wavelength conversion unit 30 and the reflected light (scattered light) on the upper surface of the wavelength conversion unit 30 are reflected on the inner surface of the reflector 50 and proceed forward (right side in the figure). Further, a condenser lens 60 is disposed on the front side of the reflector 50, and illumination light is emitted forward by these optical systems. In addition, the mirror part 70 is arrange | positioned by the front-end | tip vicinity (bottom surface) of the reflector 50 so that the light reflected by the inner surface of the reflector 50 advances to the condensing lens 60. FIG.

  FIG. 2 shows a cross-section taken along line AA of the illumination device 1 of FIG. 1 as viewed from the front side (right side of FIG. 1).

  As shown in FIG. 2, the light source 10 includes laser diodes 10a and 10b. The laser diodes 10a and 10b are made of an InGaN-based or GaN-based semiconductor, and output laser light from ultraviolet to blue-violet (wavelength 420 to 490 nm) by applying a predetermined voltage from a power source (not shown).

  The collimating lens 20 is composed of lenses 20a and 20b corresponding to the laser diodes 10a and 10b, respectively. In the illuminating device 1, the laser diodes 10 a and 10 b (or the optical axis of the laser light) are arranged with respect to a vertical axis (broken line in the drawing) perpendicular to the reference surface of the wavelength conversion unit 30 (the light emitting surface of the wavelength conversion unit 30). Are arranged in a state inclined by an angle θ. The light source 10, the collimating lens 20, and the wavelength conversion unit 30 are supported by a structure (not shown) so as to maintain a predetermined distance.

  The reflector 50 is provided with an opening 50a through which the laser light emitted from the laser diode 10a passes and an opening 50b through which the laser light emitted from the laser diode 10b passes.

  The laser beams that have passed through the openings 50a and 50b irradiate the wavelength conversion unit 30 inside the reflector 50, respectively. As shown in the drawing, the laser light emitted from the laser diode 10a and passing through the opening 50a enters the wavelength conversion unit 30 at an incident angle θ and is reflected. Since the incident angle and the reflection angle coincide with each other, the specularly reflected light is emitted from the opening 50b to the outside of the reflector 50 at the reflection angle θ.

  Similarly, laser light emitted from the laser diode 10b and passing through the opening 50b is incident on the wavelength conversion unit 30 at an incident angle θ and reflected. The regularly reflected light is emitted from the opening 50a at a reflection angle θ.

  As described above, the reflector 50 is provided with a pair of openings 50 a and 50 b that are symmetrical with respect to the vertical axis at the center of the wavelength conversion unit 30, and is incident through one of the pair of openings and is regularly reflected by the wavelength conversion unit 30. The emitted light is emitted to the outside of the reflector 50 through an opening at a position symmetrical to the incident opening. Thereby, the illuminating device 1 can prevent that the regular reflection component of incident light concentrates on one point, and color unevenness arises in illumination light.

The wavelength converter 30 includes a phosphor layer 30a that absorbs laser light emitted from the laser diodes 10a and 10b and generates fluorescence having a wavelength different from that of the laser light. The phosphor layer 30a is a layer including a phosphor that absorbs laser light as excitation light and emits light. Examples of the phosphor include Y ₃ Al ₅ O ₁₂ : Ce ³⁺ (YAG), (Si, Ba) _2. Yellow phosphors such as SiO ₄ : Eu ²⁺ and Ca _x (Si, Al) ₁₂ (O, N) ₁₆ : Eu ²⁺ can be used.

  The reflective substrate 40 disposed on the lower surface side of the phosphor layer 30a functions as a support substrate for the phosphor layer 30a, and also emits fluorescence generated in the phosphor layer 30a and laser light not absorbed by the phosphor layer 30a. Reflects in the incident direction. The reflective substrate 40 has a function of radiating heat generated in the phosphor layer 30a to the outside.

  For the reflective substrate 40 having these functions, a material having good light reflection characteristics and good thermal conductivity is used. Specifically, a metal substrate such as aluminum, silver, or a silver alloy is preferable. The wavelength conversion unit 30 is joined to the reflective substrate 40 with an organic adhesive, an inorganic adhesive, low-melting glass, metal brazing, or the like.

  For the phosphor layer 30a, the above-described phosphor powder is dispersed in glass or resin, a glass phosphor in which a luminescent center ion is added to a glass matrix, or a phosphor ceramic that does not contain a binder such as a resin. be able to. The glass may be a fluorescent paint applied.

  You may arrange | position the RGB laser diode comprised by red, green, and blue in the position of the laser diode 10a (or laser diode 10b). In this case, the light from each laser diode is guided to one optical fiber by a half mirror. Further, the wavelength converter 30 requires a light diffusing plate that diffuses the laser light. In the light diffusing plate, the light is formed into a circular shape while controlling the diffusion angle. Thereby, it is possible to create illumination light that is mixed and turned white.

  Next, with reference to FIG. 3 and FIG. 4, the relationship between the incident angle θ of the laser beam to the wavelength conversion unit 30 and the length ratio of the beam diameter will be described.

  First, considering the case where the light from the light source 10 (laser light) is irradiated onto the wavelength converter 30 from directly above (incident angle 0 °), the energy density of light is highest at the portion close to the optical axis, and from the optical axis. The energy density gradually decreases with increasing distance (Gaussian distribution). When this laser beam is applied to the wavelength conversion unit 30, the length ratio of the beam diameter (ratio of the vertical axis a and the horizontal axis b) is 1, and the beam spot is a circle of a: b = 1: 1 ( (See FIG. 4).

  In the illumination device 1 of the embodiment, the light from the light source 10 is incident on the light emitting surface of the wavelength conversion unit 30 from an oblique direction (see FIG. 2). Although the reason will be described later, the optical axis of the light source 10 and the vertical axis of the wavelength conversion unit 30 intersect each other at a predetermined inclination angle (incident angle θ) in the horizontal direction when the illumination device 1 is viewed from the front. It is desirable that the 10 optical axes intersect perpendicularly with the horizontal direction when the illumination device 1 is viewed from the side (see FIG. 1).

  As shown in FIG. 3, as the incident angle θ is increased, the beam diameter length ratio (b / a) gradually changes to a larger value. According to FIG. 3, when the incident angle θ is 60 °, the beam diameter length ratio is 2, and the beam spot is an ellipse with a: b = 1: 2 (see FIG. 4). It can also be seen that the beam diameter length ratio is about 3.5 when the incident angle θ is 70 °, and the beam diameter length ratio is about 5.8 when the incident angle θ is 80 °.

  When the illumination device 1 is used as a vehicular lamp, a wide light distribution in the lateral direction is required. For this reason, it is preferable that the light emission surface of the wavelength conversion part 30 is a rectangle whose aspect ratio is 1: 2-1: 4. According to FIG. 3, the incident angle θ at which the beam diameter length ratio is 4 is about 75 °. Therefore, when the incident angle θ is set to an angle between 60 ° and 75 °, it is optimal as a vehicle lamp. is there.

  Finally, with reference to FIG. 5A to FIG. 5C, overlapping of beam spots by a plurality of light sources will be described.

  When the lighting device 1 is used as a vehicular lamp, it is necessary to obtain a light distribution with higher luminance as it goes to the center of the video projection area. Although there is a method of increasing the brightness at the center by a member such as a lens, here, the light source 10 is arranged so that the brightness at the center of the light emitting surface of the wavelength conversion unit 30 is increased, thereby facilitating the formation of light distribution. .

  First, as shown in FIG. 5A, when the beam spot 10a ′ of the laser beam from the laser diode 10a and the beam spot 10b ′ of the laser beam from the laser diode 10b are arranged to greatly deviate from each other, the luminance peak of each other is Appears at a distance. Therefore, when the luminance distributions of the respective laser beams are superimposed (thick line in the graph), the luminance in the center (near position 0) is particularly small.

  Next, as shown in FIG. 5B, when the beam spot 10a ′ and the beam spot 10b ′ are arranged to be slightly overlapped, when the luminance distributions of the respective laser beams are superimposed, the luminance of the central region is relatively Become bigger.

  Next, as illustrated in FIG. 5C, when the beam spot 10 a ′ and the beam spot 10 b ′ are arranged to coincide with each other, the luminance distributions of the respective laser beams are completely overlapped. For this reason, the brightness in the center area is maximized, and the brightness in the center of the video projection area can be increased.

  As described above, the incident angle θ of the laser light incident on the wavelength conversion unit 30 from the laser diodes 10a and 10b is set to 60 ° to 75 °, and as shown in FIG. 5C, the beam spots 10a ′, By arranging the laser diodes 10a and 10b so that 10b 'is at the same position, it is possible to create a light distribution that is wide in the lateral direction and has a high luminance at the center.

  The illuminating device 1 of embodiment is mainly applicable to a vehicle headlamp (headlight). Moreover, you may apply the illuminating device 1 to general illumination. The above-described embodiment is an example, and various modifications other than this are possible.

  In the illuminating device 1 of the embodiment, the collimating lens 20 is disposed at the subsequent stage of the light source 10, but an optical fiber is disposed between the light source 10 and the collimating lens 20, and the light from the light source 10 is guided to the collimating lens 20. Also good. Furthermore, an optical fiber may be provided between the collimating lens 20 and the openings 50a and 50b, and the light from the light source 10 may be guided to the openings 50a and 50b. Thereby, it is possible to reduce the size of the apparatus and suppress the loss due to the propagation of light while condensing the light from the plurality of laser diodes with the lens to obtain a high output light source.

If the phosphor layer 30a of the wavelength conversion unit 30 is processed to have a shape on the surface side on which the laser light is incident, the fluorescence is easily excited. By forming an inclined surface on the surface of the phosphor layer 30a such that the incident angle of the laser beam decreases as the distance from the optical axis of the laser beam increases, the same fluorescence and reflection in each region of the surface of the phosphor layer 30a. Light is generated. Thereby, illumination light with little color unevenness can be obtained. In order to form such a structure, there is a method in which a phosphor (YAG) and Al ₂ O ₃ (alumina) which is transparent particles are compressed from a powder in a mold and fired.

  The opening of the reflector 50 does not need to match the number of the light sources 10. In addition to a pair or a plurality of openings corresponding to the light source 10, there may be openings only for emitting light.

  DESCRIPTION OF SYMBOLS 1 ... Illuminating device, 10 ... Light source, 10a, 10b ... Laser diode, 20 ... Collimating lens, 20a, 20b ... Lens, 30 ... Wavelength conversion part, 30a ... Phosphor layer, 40 ... Reflective substrate, 50 ... Reflector, 50a , 50b ... aperture, 60 ... condensing lens, 70 ... mirror part.

Claims (7)

A light source;
A light emitting unit that is irradiated with light from the light source and generates light by reflection of the irradiated light;
The light source is disposed between the light source and the light emitting unit, and has at least a pair of openings at positions symmetrical to a vertical axis perpendicular to a reference plane of the light emitting unit, and light from the light source has the pair of openings. And a reflector that irradiates the light emitting unit through the light emitting unit and reflects the light emitted from the light emitting unit with a mirror provided on the back surface. The lighting device according to claim 1.
The optical axis of the light source and the vertical axis of the light emitting unit intersect at a predetermined inclination angle in a predetermined direction,
An illumination device, wherein an optical axis of the light source and a direction orthogonal to the predetermined direction intersect perpendicularly. The lighting device according to claim 2,
The illumination device according to claim 1, wherein the predetermined inclination angle is an angle between 60 ° and 75 ° with respect to a vertical axis of the light emitting unit. In the illuminating device of any one of Claims 1-3,
The light sources are at least a pair of light sources,
The pair of light sources are arranged at positions corresponding to the pair of openings. In the illuminating device of any one of Claims 1-4,
The light source is a blue laser diode;
The light emitting unit includes a phosphor that generates yellow fluorescence when irradiated with light of the blue laser diode,
The illuminating device characterized in that the emitted light is blue light of the blue laser diode and yellow light of the fluorescence. In the illuminating device of any one of Claims 1-4,
The light source is an RGB laser diode;
The light emitting unit includes a light diffusion plate that diffuses the light of the RGB laser diode,
The illumination device according to claim 1, wherein the light emission is light diffused by the light diffusion plate. In the illuminating device of any one of Claims 1-6,
An illumination device comprising an optical fiber that guides light from the light source to the opening.