JP2014022160A - Solid-state lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid-state lighting device in which temperature rise in a wavelength conversion layer is suppressed and increased luminance can easily be achieved.SOLUTION: A solid-state lighting device comprises: a semiconductor laser capable of emitting laser beams of a wavelength range of blue-violet to blue colors; a heat conduction part; and a wavelength conversion layer. The wavelength conversion layer includes a first surface and a second surface, has a thickness of t1 (m), an area of S (m), and a heat conductivity of σ1 (WmK), and absorbs the flux of a laser beam applied to the second surface to emit wavelength conversion light while absorbing the flux of a heat-generating laser beam to emit wavelength conversion light and generating heat. When Lv (cd*m) represents the luminous surface vertical luminance, on the second surface, of the mixed light of the scattered light multiply scattered or multiply reflected by the wavelength conversion layer and the wavelength conversion light, and η(W*lm) represents the heat conversion efficiency obtained by dividing the heating value of the wavelength conversion layer by the light flux, Lv≥40×10and (t1/σ1)×η≤2×10/π(m*K*lmhold.

Description

  Embodiments described herein relate generally to a solid-state lighting device.

  The LED (Light Emitting Diode) is the mainstream of white solid state lighting (SSL) devices using solid light emitting elements.

  In this case, if the white light emitting part having the phosphor is provided so as to cover the LED chip, a substrate for heat dissipation and power feeding of the LED chip is required. If the white light emitting unit is composed only of an optical system, heat generation is small, the size and weight are reduced, and the design flexibility of the lighting device can be increased.

  For this purpose, for example, an output from a high-intensity solid-state light emitting device in the wavelength range of blue violet to blue may be efficiently coupled to an optical fiber or the like, and a white phosphor may be obtained by irradiating the separated phosphor.

  In this case, when a semiconductor laser element (LD: Laser Diode) having a narrower beam divergence angle than the LED is used, it can be optically coupled to the optical fiber efficiently.

  In the case of a white illumination device that excites a phosphor using an LD, heat generated in the LD can be discharged through a heat dissipation path that is separated from the phosphor. For this reason, in a light emission part, it is restricted to the heat_generation | fever only of fluorescent substance. Therefore, heat dissipation can be improved much more than the white illuminating device using LED. However, when it is desired to emit light with higher luminance, the phosphor itself may be deteriorated due to heat generation of the phosphor.

Japanese Patent No. 4823300

  Provided is a solid-state lighting device in which a temperature increase of a wavelength conversion layer is suppressed and high brightness can be easily achieved.

および

が成り立つ。 The solid-state lighting device according to the embodiment includes a semiconductor laser capable of emitting laser light in a blue-violet to blue wavelength range, a heat conduction unit, and a wavelength conversion layer. The wavelength conversion layer includes a first surface bonded to the heat conducting unit and a second surface opposite to the first surface, and has a thickness t1 (m) and an area S (m ² ), and thermal conductivity σ1 (Wm ⁻¹ K ⁻¹ ). The wavelength conversion layer absorbs the light beam of the laser light irradiated on the second surface to emit wavelength conversion light and generate heat. The wavelength conversion layer converts the laser light into scattered light by multiple reflection or multiple scattering. The light conversion vertical brightness on the second surface of the mixed light of the scattered light and the wavelength converted light is Lv (cd · m ⁻² ), and the heat conversion obtained by dividing the heat generation amount of the wavelength conversion layer by the light flux. When the efficiency is η _th (W · lm ⁻¹ ),

and

Holds.

  There is provided a solid-state lighting device in which a temperature increase of the wavelength conversion layer is suppressed and high brightness can be easily achieved.

FIG. 1A is a partial schematic perspective view of a light emitting unit of the solid state lighting device according to the first embodiment, and FIG. 1B is a schematic cross-sectional view taken along the line AA. FIG. 2A is a partial schematic perspective view of the light emitting unit of the solid state lighting device according to the second embodiment, and FIG. 2B is a schematic cross-sectional view taken along the line BB. It is a model perspective view of the light emission part of the solid-state lighting apparatus concerning 3rd Embodiment. It is a model perspective view of the solid-state lighting device which has the light emission part of this embodiment. FIG. 5A is a schematic perspective view of a light emitting unit having an optical unit, and FIG. 5B is a schematic cross-sectional view taken along the line CC. FIG. 6A is a schematic perspective view of a light emitting unit of a solid state lighting device according to the fourth embodiment, and FIG. 6B is a schematic cross-sectional view taken along the line DD. FIG. 7A is a schematic perspective view of the solid-state lighting device according to the fifth embodiment, and FIG. 7B is a schematic cross-sectional view taken along the line EE. It is a schematic diagram which shows the structure of the projector which is an example of the application example of a solid-state lighting apparatus. It is a block diagram which shows the function of a projector.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1A is a partial schematic perspective view of a light emitting unit of the solid state lighting device according to the first embodiment, and FIG. 1B is a schematic cross-sectional view taken along the line AA.
The solid-state lighting device includes a semiconductor laser (LD) 11 that can emit laser light in a blue-violet to blue wavelength range (405 to 490 nm), a heat conducting unit 34, and a wavelength conversion layer 32. The wavelength conversion layer 32 includes a first surface 32a bonded to the heat conducting unit 34, and a second surface (light emitting surface of the wavelength conversion layer) 32b opposite to the first surface 32a.

  The laser light irradiates the wavelength conversion layer 32 containing a phosphor or the like, and emits yellow light having a wavelength longer than the wavelength (for example, 540 to 570 nm) as the wavelength converted light. The scattered light and the wavelength-converted light that are multiple-reflected or scattered by the wavelength conversion layer 32 are mixed to become white light.

  The wavelength conversion layer 32 is represented by σ1 for thermal conductivity and t1 for thickness. As shown in FIG. 1B, a model is assumed in which the heat generated in the wavelength conversion layer 32 that has absorbed the laser light becomes a heat flow HF that flows from the wavelength conversion layer 32 through the heat conduction unit 34 and is discharged to the outside.

  The temperature of the point P2 on the surface of the heat conducting part 34 that is directly below the center of gravity P1 of the second surface 32b of the wavelength conversion layer 32 and is in contact with the first surface 32a of the wavelength conversion layer 32 is the ambient temperature of general illumination. Or the maximum value of the temperature of the heat radiating part of a general electric product, which is 60 ° C. or less. When the wavelength conversion layer 32 includes a phosphor, the temperature of the center of gravity P1 of the second surface 32b of the wavelength conversion layer 32 is 140 ° C. as a maximum value. This is a deterioration limit value of the silicone resin, and is also a limit value capable of maintaining the conversion efficiency of the phosphor. That is, the allowable value of the temperature rise ΔT from the heat conducting unit 34 is 80 ° C. For example, if the wavelength conversion layer 32 is a circle, its center of gravity P1 is the center of the circle.

In such a model, symbols of physical parameters are defined as follows.

Lv: wavelength conversion layer (light emitting surface thereof) vertical luminance (cd · m ⁻² )
F: Total luminous flux (lumen: lm)
S: Area of wavelength conversion layer (m ² )
t1: wavelength conversion layer thickness (m)
σ1: Thermal conductivity of wavelength conversion layer (Wm ⁻¹ K ⁻¹ )
R _th : Thermal resistance (KW ⁻¹ )
P _th : Calorific value (W) of wavelength conversion layer
η _th : thermal conversion efficiency (Wlm ⁻¹ )
ΔT: Temperature rise on the surface of the wavelength conversion layer (K)

  Further, the relationship between the light emitting surface vertical direction luminance Lv and the total luminous flux F is expressed by Expression (1).

Lv = F / πS Formula (1)

The amount of heat generated is determined by considering the phosphor and standard chromaticity from the specifications of the total luminous flux for large light applications. The thermal conversion efficiency η _th represents a coefficient converted into thermal power per luminous flux, and what percentage of the efficiency of the wavelength converting layer 32 and the incident power is absorbed by the wavelength converting layer 32, the luminous flux at that time Determined by. These relationships are expressed by the formula (2).

P _th = η _th × F Formula (2)

At this time, the temperature increase ΔT of the wavelength conversion layer 32 is a temperature difference between the center of gravity P1 of the second surface 32b and the point P2 on the surface of the heat conducting portion 34 immediately below the center of gravity P1, and is expressed by the equation (3). And R _th (KW ⁻¹ ) represents the thermal resistance of the wavelength conversion layer 32.

  From the equations (1) to (3), the relationship of the equation (4) is established.

If the allowable value of the temperature rise ΔT of the wavelength conversion layer 32 is determined in the equation (4), the ratio between the thickness t1 of the wavelength conversion layer 32 and the thermal conductivity σ1 is determined by the light emitting surface vertical luminance Lv and the wavelength conversion layer 32. It shows that it depends only on the heat conversion efficiency η _{th of the} . That is, the ratio between the thickness t1 and the thermal conductivity σ1 of the wavelength conversion layer 32 is not dependent area of the wavelength conversion layer 32 S, the heating value P _th of the total flux F and the wavelength conversion layer 32.

  Equation (4) gives the following important suggestions, for example. In order to reduce the optical structure of the lamp, it is necessary to reduce the area S of the wavelength conversion layer 32. In order to realize such a structure with a large amount of light, it is necessary to increase the light emitting surface vertical luminance Lv. In this case, from formula (4), it is suggested that the thickness t1 of the wavelength conversion layer 32 should be reduced and a material having a high thermal conductivity σ1 of the wavelength conversion layer 32 should be used.

A high-intensity LED with a large amount of light is generally provided with a wavelength conversion layer on a chip of 1 mm × 1 mm. Even with a chip size larger than this, it is difficult to obtain a luminous flux value of approximately 125 lumens (lm) because of the droop phenomenon in which the light emission efficiency at high current density decreases. The light emitting surface vertical luminance Lv at this time is approximately 40 Mcd · m ⁻² . In this case, it is difficult to obtain a solid state lighting device having a large light amount and a small light emitting area. On the other hand, in the first embodiment, by using an LD having a narrow divergence angle and reducing the light emission area S of the wavelength conversion layer 32, the light emission surface vertical luminance Lv per lamp is 40 Mcd · m ⁻² or more. Can be easily done. That is, in the first embodiment, the light emitting surface vertical luminance Lv is set to a range represented by Expression (5).

When the light emitting surface vertical luminance Lv is 40 Mcd · m ⁻² or more and the allowable value of the temperature rise ΔT is 80 ° C., the right side of the equation (4) is preferably in the range represented by the equation (6).

As a result, for example, a yellow phosphor made of YAG (Yttrium Aluminum Garnet) or the like is used as a wavelength conversion material, and white chromaticity (CIE1931, (Cx, Cy) = (0.33, 0.33)) is considered. And η _th = 10 ⁻³ W · lm ⁻¹ . If the wavelength conversion layer 32 includes a phosphor and a silicone layer σ1 = 0.16 Wm ⁻¹ K ⁻¹ ) provided below the phosphor, the thickness of the silicone layer may be approximately 0.1 mm or less. Further, when the wavelength conversion layer 32 includes a phosphor and a glass layer (σ1 = 1W ^m−1 K ⁻¹ ) provided below the phosphor, the thickness of the glass layer may be approximately 0.63 mm or less. I understand that.

  In practice, since the wavelength conversion layer 32 has phosphor particles dispersed in a silicone layer or a glass layer, the thickness thereof may be determined in consideration of its thermal conductivity and density. In this way, deterioration of the resin such as silicone constituting the wavelength conversion layer 32 can be suppressed, the conversion efficiency of the wavelength conversion layer 32 can be maintained, and the light emitting surface vertical luminance Lv can be increased.

FIG. 2A is a partial schematic perspective view of the light emitting unit of the solid state lighting device according to the second embodiment, and FIG. 2B is a schematic cross-sectional view taken along the line BB.
In the second embodiment, a reflective layer 35 provided between the wavelength conversion layer 32 and the heat conducting unit 34 and a heat radiator 72 attached to the outside of the heat conducting unit 34 are further provided. In addition, a plurality of laser beams are emitted from the plurality of LDs (11 a to 11 e) toward the wavelength conversion layer 32. If the wavelength conversion layer 32 contains red or green phosphor, it is easy to improve color rendering.

  When the heat conductive part 34 is a metal, a reflectance may fall in the wavelength range of blue violet-blue light. When the reflective layer 35 having a thermal conductivity higher than the thermal conductivity of the wavelength conversion layer 32 and a reflectance of the surface in contact with the wavelength conversion layer 32 is higher than the reflectance of the thermal conduction unit 34, the wavelength conversion layer 32 It becomes easy to discharge heat to the heat conducting portion 34 while increasing the light extraction rate on the second surface 32b side.

  When the thermal conductivity of the reflective layer 35 is σ2 and the thickness thereof is t2, Equation (7) is established.

Moreover, Formula (8) is formed from Formula (1), (2), (7). R _th (KW ⁻¹ ) represents the thermal resistance of the stacked body of the wavelength conversion layer 32 and the reflective layer 35.

As in the first embodiment, when the light emitting surface vertical luminance Lv is 40 Mcd · m ⁻² or more expressed by the equation (5) and the allowable value of the temperature rise ΔT is 80 ° C., the right side of the equation (8) is The range represented by (9) is preferable.

  As a result, it is possible to suppress deterioration of the resin such as silicone constituting the wavelength conversion layer 32, maintain the conversion efficiency of the wavelength conversion material, and increase the light emitting surface vertical luminance Lv.

FIG. 3 is a schematic perspective view of a light emitting unit of the solid state lighting device according to the third embodiment.
The laser light may be guided using the optical fiber 24 (24a to 24e). In this case, laser light can be introduced into one end of the optical fiber 24 and can be directly irradiated toward the wavelength conversion layer 32 from the other end of the optical fiber 24 separated from the LD. Alternatively, the wavelength conversion layer 32 can be irradiated after laser light is introduced from the optical fiber 24 to the optical unit provided on the wavelength conversion layer 32 and guided in the optical unit. By doing so, the coherent laser light can be multiple scattered or multiple reflected and emitted to the outside as scattered light. Further, when the plurality of laser beams irradiate different regions on the surface of the wavelength conversion layer 32, the wavelength conversion light can be generated more uniformly.

FIG. 4 is a schematic perspective view of a solid-state lighting device having the light emitting unit shown in FIGS.
The solid-state lighting device 5 includes a light source unit 10, a light guide unit 20, and a light emitting unit 30. The light source unit (light engine) 10 includes an LD 11 and a drive circuit 12. The LD 11 is made of a nitride-based semiconductor material and emits laser light in the blue-violet to blue wavelength range. The light emitting point on the end face of the chip of the LD 11 has a size of 10 μm or less, and its radiation angle (beam divergence) is also narrow, about 25 ° × 40 °. For this reason, LD11 and the optical fiber 24 can be optically coupled efficiently.

  The drive circuit 12 supplies a predetermined voltage or current to the LD 11. It is also possible to have a control circuit that provides a predetermined light output. Further, it is possible to detect the return light RL1 (broken line) and to have a function of stopping the driving of the LD 11 when, for example, an abnormality is detected.

  The light guide unit 20 transmits the laser light G <b> 1 to the light emitting unit 30 via the connector 26. In this case, the light guide 20 can include an optical fiber 24. The optical fiber 24 may include a plurality of fibers and transmit a plurality of laser beams, respectively.

  The light emitting unit 30 includes a heat conducting unit 34 and a wavelength conversion layer 32. As shown in FIG. 4, the light emitting unit 30 can further include an optical unit 39. In this case, the laser beam G1 incident on the optical unit 39 is guided and then irradiates the wavelength conversion layer 32. The wavelength converted light is emitted from the optical unit 39 to the outside. Further, the laser light becomes scattered light of blue-violet to blue light by multiple scattering or multiple reflection. The mixed light GT of the scattered light and the wavelength conversion light is emitted above the wavelength conversion layer 32.

  As shown in FIG. 4, if the connector 26 is provided between the light emitting unit 30 and the optical fiber 24, the connection between the light emitting unit 30 and the light source 10 can be facilitated.

FIG. 5A is a schematic perspective view of a light emitting unit having an optical unit, and FIG. 5B is a schematic cross-sectional view taken along the line CC.
The optical part 39 can be provided so as to cover the upper part of the wavelength conversion layer 32, for example. When laser light is introduced into the optical unit 39 using the optical fiber 24, a ferrule 29 can be provided at one end of the optical fiber 24. On the other hand, for example, a plurality of through holes 34c are provided in the heat conducting section 34 so as to surround the wavelength conversion layer 32, and the ferrule 29 is inserted into the through holes 34c. The laser light g <b> 1 introduced into the optical unit 39 is guided inside the optical unit 39 and irradiates the wavelength conversion layer 32. The laser beam g1 may be incident from the side surface of the optical unit 39. Thus, when the optical part 39 is provided, it becomes easy to irradiate the wavelength conversion layer 32 uniformly, and the wavelength conversion layer 32 can be sealed and its deterioration can be suppressed.

FIG. 6A is a schematic perspective view of a light emitting unit of a solid state lighting device according to the fourth embodiment, and FIG. 6B is a schematic cross-sectional view taken along the line DD.
In the fourth embodiment, the heat conducting unit 70 is made of an insulating material having high heat conductivity and translucency, and has a tube shape. The wavelength conversion layer 33 is provided on the inner wall 70 a of the tubular heat conducting unit 70. One end of the heat conducting unit 70 is bonded to the heat radiator 72. Further, the laser beam B is emitted in the radial direction while being guided through the light guide rod 74 provided along the central axis of the heat conducting unit 70. Further, when a rough surface by a frost process or the like is provided on the surface 74a of the light guide rod 74, the laser light B is multiply scattered and becomes incoherent scattered light. The mixed light is emitted radially from the outer edge 70e of the tubular heat conducting unit 70.

  When the thickness t3 of the heat conducting unit 70 is larger than the thickness t1 of the wavelength converting layer 33, the heat generated in the wavelength converting layer 33 is externally caused by the heat flow HF that flows through the heat conducting unit 70 and the radiator 72. Discharged. In the fourth embodiment, the radial thickness of the wavelength conversion layer 33 is t1. The area of the inner wall 70a of the heat conducting unit 70 is S. The area S is expressed by L1 × H when the inner circumference L1 of the tube and the height H of the heat conducting unit 70 are used.

  By adopting such a shape and further satisfying the equations (5) and (6), the deterioration of the resin such as silicone constituting the wavelength conversion layer 33 is suppressed, and the conversion efficiency of the wavelength conversion layer 33 is maintained to emit light. The surface vertical luminance Lv can be increased. Further, the mixed light GT can be emitted radially from the heat conducting portion 70 in the radial direction.

FIG. 7A is a schematic perspective view of the solid-state lighting device according to the fifth embodiment, and FIG. 7B is a schematic cross-sectional view taken along the line EE.
As shown in FIG. 7A, the laser light emitted from the LD 11 is optically coupled to one end 24a of the optical fiber 24 and introduced into an optical unit 76 disposed in the vicinity of the other end 24b.

  As shown in FIG. 7B, a wavelength conversion layer 32 having a thickness t1 and a thermal conductivity σ1 is provided on the lower surface of the optical unit 76. A reflective layer 35 having a thickness t2 and a thermal conductivity σ2 is provided on the lower surface of the wavelength conversion layer. Furthermore, the reflective layer 35 is bonded to, for example, the heat conducting unit 34. In this way, the optical unit 76 becomes a linear illumination device that can emit the mixed light GT radially toward the outer edge of the optical unit 76. In this case, by satisfying the equations (5) and (9), the deterioration of the resin such as silicone constituting the wavelength conversion layer 32 is suppressed, the conversion efficiency of the wavelength conversion layer 32 is maintained, and the light emitting surface vertical luminance is obtained. Lv can be increased.

FIG. 8 is a schematic diagram showing a configuration of a projector that is an example of an application example of the solid-state lighting device.
The LD that generates a large amount of heat and the drive circuit are housed in the light source unit 10. The light emitting unit 30 connected to the light source unit 10 by the optical fiber 24 or the like can be small in size and light in weight and low in heat generation although it can emit light with a large amount of light and high luminance. If the light source unit 10 is installed, for example, under a desk or the like, the desk is widened, and exhaust heat and noise caused by a cooling fan can be suppressed.

  The projection unit 60 that projects an image on the screen 64 is provided with a shutter including a liquid crystal device or the like in front of the light emitting unit. Since the liquid crystal device has low power consumption, it generates little heat. In addition, when wireless power feeding is performed using microwaves, the optical fiber 24 may be provided with a connector for optical signal transmission. Of course, an electrical signal transmission connector can also be provided. When the optical fiber bundle is passed through the free pipe so that the light emitting unit 30 can freely adjust the neck angle, the irradiation position can be adjusted with one touch.

FIG. 9 is a block diagram showing functions of the projector.
The projector includes a projection unit 60, the solid-state lighting device 5, a sweep signal drive unit 71, a return light sensor unit 73, and a video signal drive unit 72. The projection unit 60 includes an image unit 63, a sweep optical unit 61, and an external signal sensor unit 62. The video unit 63 may have a liquid crystal shutter.

  The laser light G1 emitted from the light source unit 10 propagates through the optical fiber 24 and enters the light emitting unit 30. The white light WL emitted from the light emitting unit 30 acts as a backlight for the video unit 63. In addition, the light source unit 10 can transmit the laser light G <b> 2 to the sweep optical unit 61.

  The return light RL1 from the optical unit 39 enters the return light sensor unit 73. The return light RL1 includes laser light and wavelength converted light reflected by the light emitting unit 30. For example, when the intensity of the yellow light component of the return light decreases with respect to the intensity of the blue light component, the return light sensor unit 73 detects this decrease and stops driving the LD provided in the light source unit 10. be able to. That is, since the solid-state lighting device 5 has a self-diagnosis function for detecting that the emitted light is in the abnormal mode, it is possible to prevent the blue light and the like from being excessively emitted and to ensure safety.

  The video signal S <b> 1 from the video signal driving unit 72 is input to the video unit 63 and the video is projected toward the screen 64. Further, the sweep optical unit 61 receives the sweep signal S2 from the sweep signal driving unit 71.

  Further, when the signal transmission system is only light, it is also possible to generate power on the light emitting head side using a part of the output of the high-power laser and transmit the control signal power through an optical fiber or the like.

  In the solid-state lighting device 5 according to the first to fifth embodiments, the temperature increase of the wavelength conversion layer is suppressed, and it is possible to emit white light with high luminance and large light quantity. In addition, the illumination system that guides the laser beam to the light emitting part of the illumination with an optical fiber cable, and unlike the illumination system using LEDs, filament light bulbs, HID lamps, etc., it is necessary to perform electrical wiring near the light emitting part of the illumination. Disappear. As a result, it can be widely used in places where installation / wiring requires waterproof / explosion-proof measures, environmental places where special equipment is required, and places where electric wiring is difficult. For example, stage lighting can be used for projection and spot lighting. In this case, the color and brightness of the local part of the minute light emitting part can be adjusted, and although the resolution is low, a great effect can be obtained as an effect.

  In the case of an illuminating device that generates a large amount of heat from the light emitting section, it is necessary to use a separate large-sized device for the spot or projection type stage illumination and the production by the laser light sweep. On the other hand, according to the first to fifth embodiments, both functions can be realized by using one small head. This can greatly change the concept of the stage and studio, and the effect is great.

  In addition, when the external signal light sensor unit 62 detects an external light signal such as infrared rays, the signal RL2 such as infrared rays and electricity can be transmitted to the light source unit 10 to control the LD on or off. Such a solid state lighting device can be used as illumination for explosion-proof equipment, crime prevention lighting capable of image recording, and the like.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 11 Semiconductor laser (LD), 20 Light guide part, 24 Optical fiber, 30 Light emission part, 32, 33 Wavelength conversion layer, 34 Heat conduction part, 35 Reflection layer, 39, 76 Optical part, 70 Heat conduction part (insulator), 72 radiator, 74 light guide rod

Claims (10)

A semiconductor laser capable of emitting laser light in the blue-violet to blue wavelength range;
A heat conduction part;
Including a first surface bonded to the heat conducting portion and a second surface opposite to the first surface; a thickness t1 (m); an area S (m ² ); and a thermal conductivity a wavelength conversion layer having σ1 (Wm ⁻¹ K ⁻¹ ), which absorbs the light flux of the laser light irradiated on the second surface to emit wavelength converted light and generate heat; ,
With
The wavelength conversion layer converts the laser light into scattered light by multiple reflection or multiple scattering,
The light emitting surface vertical luminance on the second surface of the mixed light of the scattered light and the wavelength converted light is Lv (cd · m ⁻² ),
When the heat conversion efficiency obtained by dividing the heat generation amount of the wavelength conversion layer by the light flux is η _th (W · lm ⁻¹ ),

and

Meet solid lighting device. A light guide rod for guiding the laser beam;
The heat conduction part has a shape of a tube made of an insulating material having translucency,
The wavelength conversion layer is provided on an inner wall of the tube and surrounds the light guide rod;
The solid-state lighting device according to claim 1, wherein the mixed light is emitted radially from an outer edge of the tube. A semiconductor laser capable of emitting laser light in the blue-violet to blue wavelength range;
A heat conduction part;
A first surface and a second surface opposite to the first surface; a thickness t1 (m), an area S (m ² ), and a thermal conductivity σ1 (Wm ⁻¹ K ^−1). ), The first surface is bonded to the heat conducting portion, absorbs the light beam of the laser light irradiated on the second surface, emits wavelength converted light, and generates heat. A wavelength converting layer that produces a quantity;
A reflective layer provided between the wavelength conversion layer and the heat conducting part and having a thickness t2, an area S, and a thermal conductivity σ2,
With
The wavelength conversion layer converts the laser light into scattered light by multiple reflection or multiple scattering,
The light emitting surface vertical luminance on the second surface of the mixed light of the scattered light and the wavelength converted light is Lv (cd · m ⁻² ),
When the heat conversion efficiency obtained by dividing the calorific value by the luminous flux is η _th (W · lm ⁻¹ ),

and

Meet solid lighting device. A light guide portion provided between the semiconductor laser and the wavelength conversion layer, for guiding the laser light;
An optical unit that is provided on an upper surface of the heat conducting unit so as to cover the wavelength conversion layer, guides the laser light emitted from the light guide unit, and emits the laser beam toward the wavelength conversion layer;
The solid-state lighting device according to any one of claims 1 to 3, further comprising:   The solid-state lighting device according to claim 4, wherein the light guide unit includes a plurality of optical fibers.   The solid-state lighting device according to claim 4, wherein the optical unit scatters and emits the laser light by multiple scattering or multiple reflection while guiding the laser light. An optical unit that is provided on the upper surface of the heat conducting unit so as to cover the wavelength conversion layer, and into which the laser beam emitted from the semiconductor laser is directly introduced;
The solid-state lighting device according to claim 1, wherein the laser light introduced into the optical unit is guided in the optical unit to irradiate the wavelength conversion layer.   The solid-state lighting device according to claim 7, wherein the laser light is scattered and emitted by multiple scattering or multiple reflection while being guided in the optical unit.   The solid-state lighting device according to claim 1, wherein the wavelength conversion layer emits a plurality of wavelength-converted lights.   The solid-state lighting device according to claim 1, wherein the semiconductor laser includes a plurality of laser elements.

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