JP6925174B2 - Wavelength converter - Google Patents

Description

The present invention relates to a wavelength converter that converts the wavelength of passing light from a light source.

In recent years, a lighting device including an LD (Laser Diode) or the like as a light source is known. In lighting devices such as vehicle headlights, the light color is determined to be white, so in order to convert the LD light color to white, wavelength conversion including a wavelength conversion substance such as phosphor particles The body is used (eg, Patent Documents 1 and 2).

Wavelength conversion The wavelength conversion substance in the body generates heat as the excitation light as the passing light undergoes wavelength conversion. Quenching occurs when the temperature of the wavelength converter increases. Therefore, in a wavelength converter having a general structure, a light-transmitting member for heat dissipation is joined to the light incident side of the wavelength conversion member. The translucent member conducts conduction heat from the wavelength conversion member and dissipates it to the surroundings (Example: Patent Document 1).

JP-A-2015-149394 JP-A-2015-38884

In a wavelength converter with a translucent member, when light from a light source passes through the translucent member and enters the wavelength conversion member, some of the light is on the light incident side of the translucent member as the light source side. Reflects on. Next, a part of the reflected light is totally reflected on the wavelength conversion member side on the light incident side surface of the translucent member and re-incidents on the wavelength conversion member. The re-incident position on the wavelength conversion member is a different incident position from the incident position at the time of the first reflection.

In this way, among the incident light from the light source from the wavelength converter, the emitted light due to the incident light directly incident on the wavelength conversion member without being reflected at the joint surface between the wavelength conversion member and the translucent member, and the incident light of total internal reflection. Light emitted by light may be emitted. The emitted light of the latter is a ring-shaped emitted light that surrounds the emitted light of the former. The ring-shaped emitted light affects the light distribution pattern, the image, and the like, and therefore needs to be removed.

The wavelength converters of Patent Documents 1 and 2 do not have a structure for removing or suppressing ring-shaped emitted light due to the presence of a light-transmitting member for heat dissipation.

An object of the present invention is to provide a wavelength converter capable of suppressing or removing ring-shaped emitted light while being equipped with a translucent member for heat dissipation.

The wavelength converter of the present invention is
A wavelength conversion member containing a wavelength conversion substance and performing wavelength conversion of passing light by the wavelength conversion substance, and
A first translucent member that is joined to the light incident side of the wavelength conversion member and conducts conduction heat from the wavelength conversion member.
It is characterized by including a second translucent member joined to the light incident side of the first translucent member.

According to the present invention, the first translucent member is joined to the light incident surface of the wavelength conversion member as a translucent member for heat dissipation to conduct conduction heat from the wavelength conversion member. Further, by joining the second translucent member to the light incident side of the first translucent member, the thickness (dimension in the joining direction) of the entire translucent member is sufficiently increased. The larger the thickness of the entire translucent member, the more the re-incident position of the total reflected light that is totally reflected on the surface of the second translucent member on the light incident side and re-incident on the incident side of the wavelength conversion member is the wavelength conversion member. In the plane direction of the light incident surface of, the distance from the incident position where the light incident member was first incident on the incident side of the wavelength conversion member. That is, the ring-shaped emitted light has an increased ring radius and a decreased intensity per unit area. In this way, the ring-shaped emitted light becomes inconspicuous even if it is incident on the light incident surface of the wavelength conversion member, or the incident position of the total reflected light in the plane direction of the light incident surface of the wavelength conversion member is outside the light incident surface. Become. Thereby, the ring-shaped emitted light can be suppressed or removed.

In the wavelength converter of the present invention, the incident light on the wavelength converter is reflected on the light incident surface of the wavelength converter member on the light incident side of the wavelength converter, and the reflected light generated by the reflection is the first. The joint surface between the 1 translucent member and the 2nd translucent member, or the surface of the 2nd translucent member on the light incident side, is totally reflected to the light incident surface side of the wavelength conversion member, and is totally reflected. When the total reflected light generated by the above reaches the joint surface between the wavelength conversion member and the first translucent member, the arrival position is the light incident in the plane direction of the light incident surface of the wavelength conversion member. It is preferable that the thickness and the refractive index of the first translucent member and the second translucent member are set so as to be on the outside of the surface.

According to this configuration, the light incident surface of the wavelength conversion member is reflected to the light incident side of the wavelength converter, and then is totally reflected to the junction surface side of the wavelength conversion member and the first translucent member. The total reflected light returning to the joint surface can be outside the light incident surface of the wavelength conversion member. Thereby, the ring-shaped emitted light from the light emitting surface of the wavelength conversion member can be removed.

In the wavelength converter of the present invention
When the refractive indexes n1 and n2 of the first translucent member and the second translucent member are n1> n2, respectively.
The distance between the center point of the light emitting surface and the farthest point from the center point on the light emitting surface of the wavelength conversion member is d, and the thickness of the first translucent member and the second translucent member. W1 and w2, respectively, the critical angle of light from the first translucent member into the air is θ1, the critical angle of light from the second translucent member into the air is θ2, and the first translucent member. When the critical angle θ3 of light from the sex member to the second translucent member is set,
It is preferable to set 2 · {w1 · tan θ1 + w2 · tan θ2} ≧ d and 2 · w1 · tan θ3 ≧ d.

According to this configuration, when n1> n2, total reflection is performed on the joint surface between the first translucent member and the second translucent member and the surface of the second translucent member on the light entrance test side. , The total reflected light returning toward the wavelength conversion member does not enter the light incident surface of the wavelength conversion member. Thereby, the ring-shaped emitted light from the light emitting surface of the wavelength conversion member can be removed.

In the wavelength converter of the present invention
When the refractive indexes n1 and n2 of the first translucent member and the second translucent member are n1 <n2, respectively.
The distance between the center point of the light emitting surface and the farthest point from the center point on the light emitting surface of the wavelength conversion member is d, and each of the first translucent member and the second translucent member. When the thickness of is w1 and w2, the critical angle of the light from the first translucent member into the air is θ1, and the critical angle of the light from the second translucent member into the air is θ2.
2. It is preferable to set {w1 · tan θ1 + w2 · tan θ2} ≧ d.

According to this configuration, when n1 <n2, the total reflected light that is totally reflected on the surface of the second translucent member on the light entrance test side and returned to the wavelength conversion member is the wavelength conversion member. It does not enter the light incident surface. Thereby, the ring-shaped emitted light from the light emitting surface of the wavelength conversion member can be removed.

Schematic diagram of the light emitting device. Perspective view of the wavelength converter. FIG. 2 is a cross-sectional view taken along the line III-III of FIG. Explanatory drawing of a predetermined total reflection when the refractive index of the 1st translucent member> the refractive index of a 2nd translucent member. Explanatory drawing of a predetermined total reflection when the refractive index of the 1st translucent member <the refractive index of the 2nd translucent member. Regarding the description of the ring-shaped light emission generated on the light emitting surface of the wavelength converter, FIG. 6A is a diagram showing a state in which ring-shaped light emission is generated on the light emitting surface of the wavelength converter, and FIG. 6B is the light of the wavelength converter. The figure which shows the state which the ring-shaped light emission is removed from the emission surface.

(Configuration of light emitting device)
FIG. 1 is a schematic view of the light emitting device 1. The light emitting device 1 includes a light source device 2 and a wavelength converter 3 arranged so that their central axes are aligned. The central axis of the light source device 2 and the wavelength converter 3 is also the optical axis of the light source device 2 and the wavelength converter 3.

The light source device 2 includes a substrate 5 and an LD (Laser Diode) 6 attached to the substrate 5. The laser light emitted by the LD 6 is incident on the wavelength converter 3 as incident light La. The wavelength converter 3 converts a part of the incident light La from blue to, for example, a yellow wavelength, and emits the emitted light Lb which is white by mixing the blue light and the yellow light.

(Structure of wavelength converter)
FIG. 2 is a perspective view of the wavelength converter 3. The wavelength converter 3 includes a wavelength converter 10, a first translucent member 11, a second translucent member 12, and a heat radiating frame 17.

In FIG. 2, Fo indicates a light emitting surface of the wavelength conversion member 10. The light emitting surface Fo is rectangular. O indicates the center point of the light emitting surface Fo and is located at the intersection of two diagonal lines. Pc is the central axis of the wavelength converter 3 and passes through the center point O. The incident light La and the emitted light Lb in FIG. 1 travel along the central axis Pc. d indicates the distance between the center point O and the farthest point from the center point O on the light emitting surface Fo. Since the light emitting surface Fo is rectangular, the farthest points are the vertices of the light emitting surface Fo, and there are four. d is also the distance between the center point O and the apex, which is half the length of the diagonal line.

The wavelength conversion member 10, the first translucent member 11, and the second translucent member 12 form a laminated structure arranged in this order from the light emitting side to the light incident side of the wavelength converter 3. The first translucent member 11 and the second translucent member 12 serve as a substrate for the wavelength conversion member 10. In the laminated structure, adjacent layers are joined to each other in the extending direction of the central axis Pc. The extending direction of the central axis Pc is also the optical axis direction of the wavelength converter 3 and the thickness direction (thickness direction) of each layer of the laminated structure.

The wavelength conversion member 10, the first translucent member 11, and the second translucent member 12 are rectangular in the thickness direction. The rectangles of the first translucent member 11 and the second translucent member 12 are equal in size to each other and are one size larger than the rectangle of the wavelength conversion member 10. Since the wavelength conversion member 10, the first translucent member 11, and the second translucent member 12 have a common central axis Pc, the first translucent member 11 and the second translucent member 12 and the second translucent member 12 have a common central axis Pc. The peripheral edge of the second translucent member 12 protrudes to the outside by a predetermined dimension from the peripheral edge of the wavelength conversion member 10.

FIG. 3 is a cross-sectional view taken along the line III-III of FIG. The wavelength conversion member 10 is formed in a layered shape, and has a light emitting surface Fo and a light incident surface Fi on both side surfaces of the layer. The heat radiating frame 17 is attached to the peripheral edge of the wavelength conversion member 10 so as to surround the wavelength conversion member 10. The light emitting surface Fo is composed of only the surface portion of the wavelength conversion member 10 on the light emitting side that is exposed from the heat radiating frame 17. The light incident surface Fi is composed of only the surface portion of the joint surface between the wavelength conversion member 10 and the first translucent member 11 that faces the light emitting surface Fo, excluding the peripheral portion thereof. Therefore, the light incident surface Fi has the same dimensions and shape as the light emitting surface Fo.

The heat radiating frame 17 is made of a predetermined metal such as aluminum as a material having high thermal conductivity. The heat radiating frame 17 is joined to the peripheral edge of the first translucent member 11 by surface contact, and heat is conducted from the first translucent member 11 through the joint surface. The heat generated at the central portion of the wavelength conversion member 10 is conducted as conduction heat to the central portion of the first translucent member 11, then is conducted from the central portion of the first translucent member 11 to the peripheral portion, and further. It is conducted from the peripheral edge of the first translucent member 11 to the heat radiating frame 17 and is dissipated from the heat radiating frame 17.

The second translucent member 12 has a joint surface Fb and an exposed surface Fe on both sides in the thickness direction. The joint surface Fb is a surface on which the first translucent member 11 and the second translucent member 12 are joined to each other. The exposed surface Fe is also the light incident surface of the wavelength converter 3. The joint surface Fb and the exposed surface Fe are also a surface on the light emitting side and a surface on the light incident side of the second translucent member 12, respectively. The exposed surface Fe is also the light incident surface of the wavelength converter 3.

The wavelength conversion member 10 contains phosphor particles as a wavelength conversion substance that wavelength-converts the passing light of the wavelength conversion member 10. The phosphor particles are, for example, from a material such as an oxide phosphor, a nitride phosphor, an oxynitride phosphor, a sulfide phosphor, or a fluoride phosphor as a wavelength converting substance that converts blue laser light into yellow. Become.

The thickness (layer thickness) of the wavelength conversion member 10 is, for example, 10 to 50 μm. If the thickness is less than 10 μm, it becomes difficult to make the layer thickness uniform. When the thickness exceeds 50 μm, color separation occurs due to the light guide in the wavelength conversion member 10. The particle size is preferably 100 nm to 50 μm, for example. If the particle size is small, the luminous efficiency of the phosphor particles is low, and if it is too large, the color unevenness of the wavelength conversion member 10 increases.

The wavelength conversion member 10 generates heat when the phosphor particles use the laser light of the incident light La as excitation light to generate fluorescence having a wavelength longer than the laser light, that is, when the wavelength is converted. Since the heat generated by the wavelength conversion member 10 causes quenching, the wavelength conversion member 10 needs to be cooled. The first translucent member 11 and the heat radiating frame 17 play a role of cooling the wavelength conversion member 10.

The first translucent member 11 must have high thermal conductivity in order to avoid quenching. On the other hand, since the second translucent member 12 does not have a role of cooling the wavelength conversion member 10, it does not have to have sufficient thermal conductivity. The second translucent member 12 is provided to increase the dimension in the thickness direction between the light incident surface Fi and the exposed surface Fe. Therefore, for the second translucent member 12, a material is selected that satisfies at least either low cost or good workability, although the thermal conductivity is inferior to that of the first translucent member 11.

The first translucent member 11 is made of, for example, a single crystal material such as sapphire, single crystal GaN or single crystal YAG, or a polycrystalline material such as polycrystalline Al ₂ O ₃ , polycrystalline MgO, or polycrystalline ZrO ₂ .

The second translucent member 12 is made of, for example, glass or polycrystalline ceramic. Examples of the joining method between the first translucent member 11 and the second translucent member 12 include an optical contact method, a fusion bonding method, a hot press method, and a hot isotropic pressurization method (HIP method).

There are, for example, two methods for joining the wavelength conversion member 10 and the first translucent member 11. The first joining method is to manufacture the wavelength conversion member 10 as a molded body and join or bond the molded body to the first translucent member 11 as a substrate. The second joining method is to form a layer of the wavelength conversion member 10 on the first translucent member 11 as a substrate.

The wavelength conversion member 10 used in the first bonding method is made of, for example, a single crystal phosphor, a phosphor ceramic, a phosphor-dispersed glass, a phosphor-dispersed resin sheet, or the like. In this case, there is no bonding layer such as diffusion bonding between the wavelength conversion member 10 and the first translucent member 11. Therefore, for example, an adhesive is used to bond the wavelength conversion member 10 and the first translucent member 11 to each other. As such an adhesive, there is a transparent adhesive such as an organic adhesive or an inorganic adhesive.

The second joining method uses diffusion joining or the like. Therefore, as the wavelength conversion member 10, for example, a phosphor + ceramic binder, a phosphor + glass binder, or a phosphor + resin binder is used. As the diffusion bonding method, for example, a dispensing method, a rotary coating method, a printing method, or a spraying method is used.

(Ring-shaped light emission prevention structure)
4 and 5 are explanatory views of total reflection occurring in the wavelength converter 3. FIG. 4 is an explanatory diagram of predetermined total reflection when the refractive index n1 of the first translucent member 11> the refractive index n2 of the second translucent member 12. FIG. 5 is an explanatory diagram of predetermined total reflection when the refractive index n1 of the first translucent member 11 <the refractive index n2 of the second translucent member 12.

Items common to FIGS. 4 and 5 will be described. Both FIGS. 4 and 5 are cross-sectional views of only the half part on the right side of the central axis Pc when the wavelength converter 3 is cut along the diagonal line of the rectangular light emitting surface Fo. The total reflection in the wavelength converter 3 is symmetrical with respect to the central axis Pc.

In FIGS. 4 and 5, for convenience of explanation, auxiliary lines P1 to P4 parallel to the central axis Pc are shown separately from the central axis Pc. The definitions of the auxiliary lines P1 to P4 are as follows.
P1: Auxiliary line passing through the intersection on the midpoint O side of the two intersections of the fully reflected light Lrw and the junction surface Fb described later P2: Passing through the midpoint between the center point O and the apex on the rectangular light emitting surface Fo Auxiliary line P3: Auxiliary line passing through the intersection on the apex side of the two intersections of the fully reflected light Lrw and the junction surface Fb, which will be described later P4: Auxiliary line passing through the apex Since the thickness of the wavelength conversion member 10 is very thin. , The center point O and the apex defined on the rectangular light emitting surface Fo can be regarded as the center point and the apex on the rectangular light incident surface Fi.

In FIGS. 4 and 5, the definitions of Lru and Lrw are as follows.
Lru (Fig. 4 only): Totally reflected light at the intersection of the junction surface Fb and the auxiliary line P3 Lrw: Totally reflected light at the intersection of the exposed surface Fe and the auxiliary line P3 Note that the light incident surface Fi Of the incident light La reflected on the exposed surface Fe side, the light reflected (including total reflection) by the exposed surface Fe is emitted from the exposed surface Fe to the outside of the wavelength converter 3, and the light incident surface Fi Never go back to the side.

Of each code, the definitions of thickness and angle are as follows.
w1: Thickness of the first translucent member 11 w2: Thickness of the second translucent member 12 θ1: Critical angle when light travels from the first translucent member 11 into the air θ2: Light is the second translucent member Critical angle when traveling from the sex member 12 into the air θ3: Critical angle when light travels from the first translucent member 11 to the second translucent member 12 when the refractive index n1> refractive index n2 The angle is equal to the angle of incidence when total reflection occurs.

Strictly speaking, θ1 must be defined as the critical angle when light enters the wavelength conversion member 10 from the first translucent member 11. However, since the wavelength conversion member 10 is extremely thin, the critical angle when light enters the wavelength conversion member 10 from the first translucent member 11 can be regarded as θ1.

If the refractive index n of air is defined as the refractive index na, and θ1 to θ3 are expressed by the refractive index n of light, it becomes as follows.
θ1 = arcsin (na / n1)
θ2 = arcsin (na / n2)
θ3 = arcsin (n1 / n2)
In addition, "arcsin" means an inverse sine function.

Before explaining the details of FIGS. 4 and 5, the reason for explaining the predetermined total reflected light Lru and Lrw in FIGS. 4 and 5 will be described with reference to FIG.

On the light incident surface Fi of the wavelength conversion member 10, in addition to the light directly incident (hereinafter referred to as “primary incident light”) like the incident light La, a part of the incident light La is on the exposed surface Fe side. There is light that is reflected, further completely reflected by the joint surface Fb or the exposed surface Fe, and then incident on the light incident surface Fi again (hereinafter, referred to as “secondary incident light”).

FIG. 6 relates to a ring-shaped light emitting 25 generated on the light emitting surface Fo of the wavelength converter 3. FIG. 6A shows a state in which the ring-shaped light emitting 25 is generated on the light emitting surface Fo of the wavelength converter 3. FIG. 6B shows a state in which the ring-shaped light emitting 25 is removed from the light emitting surface Fo of the wavelength converter 3.

The secondary incident light includes a first total reflection light totally reflected by the joint surface Fb and a second total reflection light totally reflected by the exposed surface Fe. The reason why only the total reflected light is considered as the secondary reflected light is that the intensity of the reflected light of the normal reflection is remarkably smaller than that of the fully reflected light. That is, the reflected light of normal reflection also produces the ring-shaped light emission 25 described later, but the intensity is low and there is no problem.

When the first and second total reflected lights are incident on the inside of the circumferential contour of the light incident surface Fi in the plane direction of the light incident surface Fi, a ring-shaped light emitting 25 having a high intensity appears on the light emitting surface Fo (FIG. 6A). The central emission 23 is the emitted light caused by the primary incident light, and appears at the center point O. On the other hand, the ring-shaped light emitting 25 appears so as to surround the central light emitting 23. s indicates the radius of the inner circumference circle of the ring-shaped light emitting 25 centered on the center point O.

The intensity of the ring-shaped light emitting 25 is maximized at the inner peripheral edge and gradually decreases toward the outside. The ring-shaped light emitting 25 lowers the quality of the light distribution pattern, the image, and the like generated by the emitted light Lb. It is desired to remove or suppress the ring-shaped light emission 25 while leaving only the central light emission 23 on the light emission surface Fo.

FIG. 6B shows that the radius s of the inner circumference of the ring-shaped light emitting 25 is the distance d or more (s ≧ d). s ≧ d means that when the joint surface between the wavelength conversion member 10 and the first translucent member 11 (the joint surface is one size larger than the light incident surface Fi) is reached, the arrival position is the light incident surface Fi. It means that it is on the apex of the light incident surface Fi or outside the apex in the plane direction of.

From this, as shown in FIG. 6B, if the values of each factor of the wavelength converter 3, specifically the thickness and the refractive index, are set so that s ≧ d, the ring is formed from the light emitting surface Fo. It can be understood that the state light emission 25 is removed.

In FIGS. 4 and 5, the total reflected light Lru (first total reflected light) and the total reflected light Lrw (second total reflected light) as the secondary incident light due to the total reflection are the wavelength conversion member 10 and the first. The return position returned to the joint surface with the translucent member 11 is the rectangular apex (the intersection of the light incident surface Fi and the auxiliary line F4) as the farthest point from the center point O on the light incident surface Fi. Shows the time. If the return positions of the totally reflected lights Lru and Lrw are on the auxiliary line F4 or to the right of the auxiliary line F4, the totally reflected lights Lru and Lrw do not enter the wavelength conversion member 10 from the light incident surface Fi. This means the state of FIG. 6B.

As shown in FIG. 4, when n1> n2, the total reflected light due to the secondary incident light is the total reflected light Lru (first total reflected light) and the total reflected light Lrw (second total reflected light). become. Therefore, the conditional expression that does not generate the ring-shaped light emitting 25 on the light emitting surface Fo is such that the incident positions of the total reflected light Lru and the totally reflected light Lrw are outside the apex of the light incident surface Fi in the plane direction of the light incident surface Fi. , And specifically, the following (Equation 1) and (Equation 2).
2. {w1, tan θ1 + w2, tan θ2} ≧ d ... (Equation 1)
2 ・ w1 ・ tan θ3 ≧ d ・ ・ ・ (Equation 2)
In the above (Equation 1) and (Equation 2), the left side corresponds to s.

Further, as shown in FIG. 5, when n1 <n2, the total reflected light by the secondary incident light is only the total reflected light Lrw (second total reflected light). Therefore, the conditional expression that does not generate the ring-shaped light emitting 25 on the light emitting surface Fo is set so that the incident position of the total reflected light Lrw is outside the apex of the light incident surface Fi in the plane direction of the light incident surface Fi. Specifically, it becomes the following (Equation 3).
2. {w1, tan θ1 + w2, tan θ2} ≧ d ... (Equation 3)
In the above (Equation 3), the left side corresponds to s.

(Modification example)
A film having wavelength selectivity can be formed between the wavelength conversion member 10 and the first translucent member 11. The film allows only one-way passage from the first translucent member 11 to the wavelength conversion member 10 at the joint surface between the wavelength conversion member 10 and the first translucent member 11, and passes in the opposite direction. To prevent or suppress. As a result, among the fluorescence generated by wavelength conversion by the wavelength conversion member 10, the fluorescence that tends to return to the first translucent member 11 is blocked by the film, and the first transmission from the wavelength conversion member 10 is blocked. It is not possible to enter the optical member 11. As a result, it is possible to prevent the fluorescence that has entered from the wavelength conversion member 10 toward the first translucent member 11 to become reflected light (including total reflected light) and cause the ring-shaped light emission 25 to be generated. NS.

An antireflection film can be formed on the exposed surface Fe. The antireflection film is a second translucent member having a total reflection angle or less for fluorescence and backward scattered excitation light traveling from the wavelength conversion member 10 to the second translucent member 12 in the direction opposite to the incident light La. It suppresses the reflection of the light incident from the 12 side to the light incident surface Fi side. As a result, stray light can be suppressed and the quality of the emitted light Lb can be improved.

In the present embodiment, with respect to the thickness w1 of the first translucent member 11 and the thickness w2 of the second translucent member 12, a predetermined thickness can be secured for the entire first translucent member and the second translucent member. If, w1 ≧ w2 may be satisfied.

In the present embodiment, the light emitting surface Fo and the light incident surface Fi are rectangular. However, in the present invention, the light emitting surface Fo and the light incident surface Fi can also have a circular shape or other shapes. When the light emitting surface Fo and the light incident surface Fi are circular, the farthest point from the center point 0 on the light emitting surface Fo is each position on the circumference of the light emitting surface Fo. Therefore, the distance d between the center point O and the farthest point of the light emitting surface Fo on the light emitting surface Fo is the radius of the light emitting surface Fo.

In the present embodiment, the wavelength conversion substance of the wavelength conversion member 10 changes the wavelength of blue to the wavelength of yellow. However, the wavelength conversion substance of the wavelength conversion member of the present invention may be one that converts other wavelengths.

1 ... light emitting device, 3 ... wavelength converter, 10 ... wavelength conversion member, 11 ... first translucent member, 12 ... second translucent member, Lru ... total Reflected light (first total reflected light), Lrw ... total reflected light (second total reflected light), Fi ... light incident surface, Fb ... junction surface, Fe ... incident side exposed surface, O ... center point, d ... distance.

Claims (3)

It is a wavelength converter
A wavelength conversion member containing a wavelength conversion substance and performing wavelength conversion of passing light by the wavelength conversion substance, and
A first translucent member that is joined to the light incident side of the wavelength conversion member and conducts conduction heat from the wavelength conversion member.
A second translucent member joined to the light incident side of the first translucent member is provided.
The incident light on the wavelength converter is reflected on the light incident surface of the wavelength converter on the light incident side of the wavelength converter, and the reflected light generated by the reflection is the first translucent member and the first translucent member. The total reflected light generated by the total reflection is totally reflected to the light incident surface side of the wavelength conversion member on the joint surface with the two translucent members or the surface on the light incident side of the second translucent member. When the joint surface between the wavelength conversion member and the first translucent member is reached, the arrival position is outside the light incident surface in the plane direction of the light incident surface of the wavelength conversion member. A wavelength converter characterized in that the thickness and refractive index of the first translucent member and the second translucent member are set. A wavelength conversion member containing a wavelength conversion substance and performing wavelength conversion of passing light by the wavelength conversion substance, and
A first translucent member that is joined to the light incident side of the wavelength conversion member and conducts conduction heat from the wavelength conversion member.
A second translucent member joined to the light incident side of the first translucent member is provided .
When the refractive indexes n1 and n2 of the first translucent member and the second translucent member are n1> n2, respectively.
The distance between the center point of the light emitting surface and the farthest point from the center point on the light emitting surface of the wavelength conversion member is d, and the thickness of the first translucent member and the second translucent member. W1 and w2, respectively, the critical angle of light from the first translucent member into the air is θ1, the critical angle of light from the second translucent member into the air is θ2, and the first translucent member. When the critical angle of light from the sex member to the second translucent member is θ3,
2. A wavelength converter characterized in that {w1 · tan θ1 + w2 · tan θ2} ≧ d and 2 · w1 · tan θ3 ≧ d. A wavelength conversion member containing a wavelength conversion substance and performing wavelength conversion of passing light by the wavelength conversion substance, and
A first translucent member that is joined to the light incident side of the wavelength conversion member and conducts conduction heat from the wavelength conversion member.
A second translucent member joined to the light incident side of the first translucent member is provided .
When the refractive indexes n1 and n2 of the first translucent member and the second translucent member are n1 <n2, respectively.
The distance between the center point of the light emitting surface and the farthest point from the center point on the light emitting surface of the wavelength conversion member is d, and each of the first translucent member and the second translucent member. When the thickness of is w1 and w2, the critical angle of the light from the first translucent member into the air is θ1, and the critical angle of the light from the second translucent member into the air is θ2.
2. A wavelength converter characterized in that {w1, tan θ1 + w2, tan θ2} ≧ d.

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