JP2017050286A - Led lighting device and light guide member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact LED lighting device which is low in loss and low in heat generation.SOLUTION: An LED lighting device of the embodiment includes: an LED light source (11); a transparent member (12) which is transparent and is provided by covering the LED light source; and a light scattering member (13) arranged inside the transparent member being separated from the LED light source. A distance Lbetween the LED light source and the light scattering member, and an area C of a light-emitting surface of the LED light source satisfy a predetermined relation. The length Lof the light scattering member and an absorption coefficient μ(1/mm) of the light scattering member satisfy a predetermined relation. A diameter dof the bottom surface of the light scattering member, the distance Land a refractive index n of the transparent member satisfy a predetermined relation.SELECTED DRAWING: Figure 2

Description

  Embodiments described herein relate generally to an LED lighting device and a light guide member.

  In recent years, attention has been paid to a technique for reducing loss due to return light by a remote phosphor. In a typical remote phosphor, an LED chip is disposed on a reflector made of a specular reflector or a diffuse reflector, and a fluorescent layer is formed in a dome shape so as to cover it. The fluorescent layer is arranged at a certain distance from the LED chip, thereby reducing the return light to the LED chip.

  However, if the loss due to the return light is reduced by the remote phosphor as described above, it is inevitable that the entire illumination device including the phosphor layer and the LED becomes large. For example, when the size of the LED chip is 1 mm, the overall size of the lighting device is about 1 to 2 cm.

US Patent Application Publication No. 2010/0308354

  The problem to be solved by the present invention is to provide a compact LED lighting device with low loss and low heat generation by the remote phosphor effect.

The LED illumination device according to the embodiment includes an LED light source having a light emission surface with an area C and having a light distribution substantially symmetric about a light distribution symmetry axis intersecting the light emission surface, and the light emission surface of the LED light source. A transparent member that is provided so as to be substantially symmetric with respect to the light distribution symmetry axis of the LED light source; and a diameter d _{1 of} the bottom surface that is disposed inside the transparent member and faces the light emitting surface; and the light distribution symmetry A light scattering member having a length L ₁ along the axis and substantially symmetric with respect to the light distribution symmetry axis. The distance L ₂ between the LED light source and the light scattering member and the area C of the light emitting surface of the LED light source satisfy the relationship represented by the following formula (1).
The length L ₁ of the light scattering member along the second symmetry axis and the coefficient μ (1 / mm) satisfy the relationship of the following formula (2).
The diameter d ₁ of the bottom surface of the light scattering member, the distance L _2, and the refractive index n of the transparent member satisfy the relationship of the following formula (3).

The light guide member of the embodiment is provided so as to cover the light emitting surface of the LED light source having a light emitting surface with an area C and having a light distribution that is substantially symmetrical around a light distribution symmetry axis intersecting the light emitting surface. A transparent member that is substantially symmetric with respect to the light distribution symmetry axis of the LED light source, a diameter d _{1 of} a bottom surface that is disposed inside the transparent member and faces the light emitting surface, and a length along the light distribution symmetry axis A light scattering member having a thickness L _{1 and} substantially symmetric with respect to the light distribution symmetry axis. The distance L ₂ between the LED light source and the light scattering member and the area C of the light emitting surface of the LED light source satisfy the relationship represented by the following formula (1).
The length L ₁ of the light scattering member along the light distribution symmetry axis and the coefficient μ (1 / mm) satisfy the relationship of the following formula (2).
The diameter d ₁ of the bottom surface of the light scattering member, the distance L _2, and the refractive index n of the transparent member satisfy the relationship of the following formula (3).

  The light guide member of the embodiment is disposed inside the transparent member having a light incident surface, a transparent member having an outer peripheral surface extending in a direction intersecting the light incident surface from an outer peripheral edge of the light incident surface, and And a light scattering member that scatters light incident on the transparent member via the incident surface, and the outer peripheral surface of the transparent member has a region surrounding the light scattering member, and the region is An inclined surface inclined inward as the distance from the incident surface increases.

The perspective view showing the LED lighting apparatus concerning one Embodiment. Schematic which shows the cross section of the LED lighting apparatus concerning one Embodiment. The schematic diagram showing the light tracking result of the LED lighting apparatus concerning one Embodiment. The graph which shows the relationship between the vertical light distribution angle and luminous intensity of the LED lighting apparatus concerning one Embodiment. The perspective view which shows the LED lighting apparatus concerning other embodiment. Schematic which shows the cross section of the LED lighting apparatus shown in FIG. The figure for demonstrating operation | movement of the LED lighting apparatus shown in FIG. Schematic which shows the cross section of the LED lighting apparatus concerning other embodiment. Schematic which shows the cross section of the LED lighting apparatus concerning other embodiment. Schematic which shows the cross section of the LED lighting apparatus concerning other embodiment. Schematic which shows the cross section of the LED lighting apparatus concerning other embodiment. The perspective view which shows the LED lighting apparatus concerning other embodiment.

  The embodiment will be specifically described below.

  As shown in FIG. 1, the LED illumination device 10 according to an embodiment includes an LED light source 11 and an axially symmetric transparent member 12 that covers the LED light source. An axially symmetric light scattering member 13 is disposed away from the light source 11.

  The LED light source 11 has a planar light emitting surface and emits light in the ultraviolet light region or visible light region. For example, an LED chip that emits monochromatic light having a peak wavelength of 390 to 460 nm can be used, and more specifically, a blue LED chip that emits light having a peak wavelength of 450 nm can be used.

  In the present embodiment, the light distribution from the LED chip has a light distribution symmetry axis, and is a distribution close to symmetry with respect to this light distribution symmetry axis. Examples of the light distribution include Lambertian, but are not limited thereto. The light distribution symmetry axis can pass, for example, near the center in the light emitting surface of the LED chip, but is not limited thereto, and may pass through any point in the same plane as the light emitting surface of the LED chip. .

  The LED light source 11 may be placed on the substrate 14 as necessary. Although the board | substrate 14 is not specifically limited, A mounting surface can be comprised with the material which diffusely reflects visible light. In this case, the light distribution can be increased. Or the mounting surface of a board | substrate may be comprised with the material transparent with respect to visible light. Also in this case, the light passing through the substrate increases, and the light distribution can be increased. Examples of the material that diffuses and reflects visible light include metals such as aluminum and white resin, and examples of the material transparent to visible light include transparent resin.

The axially symmetric transparent member 12 can be made of a transparent material that absorbs little visible light. The transparent material may be either an inorganic material or an organic material. Examples of the inorganic material include glass and transparent ceramics. Specific examples of the organic material include transparent resins selected from acrylic resins, silicone resins, epoxy resins, polycarbonates, polyethylene terephthalate (PET) resins, polymethyl methacrylate (PMMA) resins, and the like. Here, the term “transparent” means that visible light is transmitted, and unless otherwise specified, is used in the following sense. There is a relationship represented by the following formula (A) between the refractive index n of the transparent member and the total reflection angle θ _c .

  The axially symmetric light scattering member 13 disposed inside the axially symmetric transparent member 12 can contain white particles that scatter ultraviolet light or visible light from the LED light source 11. Examples of the white particles include techpolymer. Alternatively, the light scattering member 13 may contain phosphor particles. When phosphor particles are contained, the light scattering member can be referred to as a phosphor layer. Examples of the phosphor particles include yellow light emitting phosphors. The yellow light emitting phosphor partially absorbs light from the LED light source and emits light in the visible region on the long wavelength side. In addition to the fluorescent layer containing yellow light emitting phosphor particles, a fluorescent layer containing red light emitting phosphor particles may also be provided inside the axially symmetric transparent member 12.

  White particles and phosphor particles can be dispersed in a transparent resin and used to form the axially symmetric light scattering member 13. Or you may comprise the axially symmetric light-scattering member 13 only by particle | grains. For example, such an axisymmetric light scattering member can be configured by providing a space in a predetermined region inside the axisymmetric transparent member 12 and filling the space with particles. In this case, there is an advantage that it can be easily manufactured.

  Further, a metal housing may be provided inside the axisymmetric light scattering member 13 and a power supply circuit may be provided inside. As a result, heat generated from the LED and the power supply circuit is transmitted from the metal casing to the axially symmetric transparent member 12, and is then radiated to the outside. As a result, the heat dissipation characteristics are improved. Further, since the power supply circuit is provided inside the metal housing, the entire lighting device can be made compact.

  The transparent resin for dispersing the particles to form the light scattering member is not limited to those described above, and any transparent resin that is transparent to visible light and can hold the particles inside is used. be able to.

In general, the absorption coefficient μ [1 / mm] of the light scattering member is obtained when a parallel light beam collimated in a direction orthogonal to the flat plate is irradiated to a flat light scattering member having a thickness of h [mm]. It can be defined using the amount of transmission. When the incident intensity of parallel rays is I ₀ and the transmission intensity is I _T , the absorption coefficient μ is expressed by the following formula (B).

In FIG. 2, the schematic structure of the cross section of the LED lighting apparatus concerning one Embodiment is shown. In order to clarify the closest distance L ₂ between the axially symmetric light scattering member 13 and the LED light source 11, in FIG. 2, the axially symmetric transparent member 12 is drawn so as not to contact the substrate 14. The axisymmetric transparent member is provided in contact with the substrate 14.

  The light distribution symmetry axis of the LED light source 11 is represented by the reference symbol ax. The symmetry axis of the axisymmetric transparent member 12 substantially coincides with the light distribution symmetry axis ax, and the symmetry axis of the axisymmetric light scattering member 13 also substantially coincides with the light distribution symmetry axis ax. The light emitted from the LED light source 11 is required to pass through the light scattering member 13 and be irradiated to the outside of the LED illumination device. If the light distribution symmetry axis of the LED light source is within the range of product variations, it can be considered that the symmetry axes substantially coincide. The light emission direction side along the light distribution symmetry axis ax is the positive direction or the upward direction, and the same applies to the following.

The closest distance L ₂ between the light scattering member 13 and the LED light source 11 and the area C of the light emitting surface of the LED light source 11 satisfy the relationship represented by the following formula (1).

  As a result, a sufficient remote phosphor effect can be obtained.

Further, the length L ₁ of the axially symmetric light scattering member along the symmetry axis (here, defined as the minimum length of the section in which the axially symmetric light scattering member is accommodated), and the axially symmetric light scattering member The relationship of the following formula (2) is established with the absorption coefficient μ (1 / mm).

Furthermore, the relationship of the following formula (3) is established among the diameter d ₁ of the bottom surface of the light scattering member, the closest distance L _2, and the refractive index n of the axisymmetric transparent member.

  By satisfying the relationship represented by the above formula (2), direct light from the LED light source 11 can surely pass through the light scattering member 13 without deviating from the light scattering member 13 and passing outside the illumination device. .

  Moreover, the following effects are acquired by the relationship of said (3). That is, a part of the direct light from the LED light source 11 escapes from being scattered at the bottom of the light scattering member 13 and is totally reflected by the side surface parallel to the axis of symmetry of the axisymmetric transparent member. Scattered upward (more distant from the LED light source 11). As a result, the direct light from the LED light source 11 is all scattered at the bottom of the light scattering member 13, and the remote phosphor effect is enhanced.

  The cross section orthogonal to the symmetry axis of the axially symmetric light scattering member 13 is included in the cross section of the axially symmetric transparent member 12 in a plane including the cross section. That is, the periphery of the light scattering member 13 is reliably covered with the transparent member 12 in a plane orthogonal to the symmetry axis. Furthermore, it is assumed that the surface obtained by projecting the axially symmetric transparent member 12 onto the light emitting surface of the LED light source 11 along the axis of symmetry includes the light emitting surface. This means that the light emitting surface of the LED light source 11 is included in a surface orthogonal to the symmetry axis of the axisymmetric transparent member 12. In other words, the surface having the largest diameter in the axisymmetric transparent member 12 is larger than the light emitting surface of the LED light source 11.

  By satisfying the above conditions, a compact LED lighting device can be obtained in addition to low loss and low heat generation.

The light tracking result of the LED lighting device according to the embodiment is as shown in FIG. From the light tracking result shown in FIG. 3, the direct light from the LED light source 11 hits the light scattering member 13 and is scattered, and the direct light from the LED light source 11 is totally reflected by the axisymmetric transparent member 12, and the light scattering member 13. It can be seen that the light is scattered.
In FIG. 4, the light distribution of the LED lighting apparatus concerning one Embodiment is shown. In FIG. 4, the horizontal axis represents the light distribution angle (deg.), And the vertical axis represents the luminous intensity (normalized). From this figure, the light distribution angle at which the luminous intensity is halved is about 145 °, and the ½ light distribution angle (which is twice the light distribution angle at which the luminous intensity is half the peak) is 290 °. From this, it can be seen that a 1/2 light distribution angle of 290 ° is achieved.

  FIG. 5 is a perspective view of an LED lighting device according to another embodiment. The LED illumination device 10 ′ shown in the figure is basically the same as the structure shown in FIG. 1 except that the axially symmetric transparent member 12 and the axially symmetric light scattering member 13 covering the LED light source are cylindrical. FIG. 6 shows a cross section along the axis of symmetry of the LED lighting device 10 ′ shown in FIG. 5.

  Here, a blue LED chip having a peak wavelength of 450 nm and a square light emitting surface is used as the LED light source 11. The length of one side of the LED chip is 1 mm, and the thickness of the light emitting surface of the LED chip is 200 μm. The shape and dimensions of the light emitting surface of the LED chip can be selected as appropriate, and are not limited thereto.

  The LED light source 11 is disposed on an aluminum substrate 14 and is covered with an axisymmetric transparent member 12. The axially symmetric transparent member 12 has a cylindrical shape with the light distribution symmetry axis ax as the symmetric axis, and the bottom surface thereof is in contact with the substrate 14. Here, the transparent member 12 is configured using PMMA (refractive index n = about 1.5).

  The axially symmetric light scattering member 13 disposed inside the axially symmetric transparent member 12 has a cylindrical shape having a light distribution symmetry axis ax as an axis of symmetry, and is composed of a silicone resin layer containing spherical yellow light emitting phosphor particles. The The yellow light emitting phosphor particles are uniformly dispersed in the silicone resin layer. The yellow light-emitting phosphor particles absorb blue light emitted from the LED light source 11 and emit light having a peak wavelength of 550 nm, for example. The absorption coefficient μ [1 / mm] of the axisymmetric light scattering member 13 containing such yellow-emitting phosphor particles is set to 0.1.

Here, since the area C of the light emitting surface of the LED light source 11 is 1 mm ^2, it is calculated as the following formula.

In the example shown in FIG. 6, the closest distance L ₂ between the LED light source 11 and the axially symmetric light scattering member 13 is 3 mm, which satisfies the relationship represented by the following formula (1).

In addition, since the absorption coefficient μ [1 / mm] of the axially symmetric light scattering member 13 is 0.1, the following equation is calculated.

In the example shown in FIG. 6, the length L ₁ of the axisymmetric light scattering member 13 is 3.0 mm, which satisfies the relationship represented by the following formula (2).

Using the above-mentioned closest distance L ₂ and refractive index n = about 1.5, the following formula is calculated.

In the example shown in FIG. 6, the diameter d ₁ of the axially symmetric light scattering member 13 is 1.41 mm, which satisfies the relationship represented by the following formula (3).

In the example shown in FIG. 6, the diameter d ₀ of the axisymmetric transparent member 12 is 3 mm, while the diameter d ₁ and the closest distance L ₂ of the axially symmetric light scattering member 13, represented by the following formula (4) Relationship is established.

  The effect of the LED lighting apparatus of this embodiment is demonstrated as follows.

  However, this operation will be described for the case where a phosphor is encapsulated as the axially symmetric light scattering member 13. In the case of enclosing white particles, long wavelength conversion by the phosphor does not occur, but the other functions are the same.

  Part of the blue light emitted from the LED light source 11 composed of a blue LED chip directly hits the axially symmetric light scattering member 13 containing yellow phosphor particles, and is scattered and absorbed. Part of the light from the LED light source 11 is scattered and absorbed by the light scattering member 13 after being totally reflected at the axially symmetric transparent member 12. Further, the remaining part of the emitted light is not totally reflected by the transparent member 12 but is emitted outside the transparent member 12.

  On the other hand, the light scattering member 13 absorbs blue light and emits yellow light, which is light on the longer wavelength side, in all directions (isotropic).

  At this time, the blue light scattered by the light scattering member 13 and the yellow light emitted and scattered are returned to the LED light source 11 and absorbed. The loss due to such return light is conventionally about 40 to 60% (for example, SC Allen, “ELiXIR-Solid-State Luminaire With Enhanced Light Extraction by Internal Reflection”, Journal of Display Technology, vol. 3, No. 2, 2007). This loss can be reduced by sufficiently separating the LED light source 11 and the light scattering member 13. This is commonly called a remote phosphor.

A part of the light emitted from the bottom surface of the light scattering member 13 closest to the LED light source 11 returns to the LED light source 11. The ratio can be roughly estimated to be a solid angle in which the LED light source 11 is expected with respect to all solid angles around the light scattering member 13. That is, it is represented by the following formula (5).

The smaller the value represented by the above formula (5), the smaller the return light from the light scattering member 13 to the LED light source 11. On the other hand, in order to obtain the remote phosphor effect, the value represented by the above formula (5) is required to be at least smaller than 1. Therefore, in order to realize the remote phosphor effect, the relationship represented by the following formula (1) must be satisfied.

In this embodiment, since C = 1 mm ² , the ratio of the return light represented by the above formula (5) is about 0.8%.
Further, when the LED light source 11 and the light scattering member 13 are separated as described above, the temperature becomes lower than that in the case where the light scattering member 13 is close to the LED light source. Thereby, deterioration of the phosphor contained in the light scattering member 13 can be prevented (for example, N. Narendran, “Improved Perfomance White LED”, Fifth International Conference on Solid State Lighting, Proceedings of SPIE 5941, 45-50). , 2005).

White light can be realized by appropriately mixing blue light from the LED light source and yellow light from the phosphor particles. When the direct light from the LED light source 11 reaches the outside, the visible luminance becomes too high. In order to avoid this, more than half of the light emitted from the blue LED chip and emitted along the light distribution symmetry axis ax needs to be absorbed by the light scattering member 13. Here, the intensity of light propagating in the light scattering member 13 along the light distribution symmetry axis ax is I [W / mm ² ], and the intensity of light immediately before hitting the light scattering member 13 is I ₀ [W / mm ^2]. ] (I / I ₀ ) is expressed by the following formula (6).

(Where μ is the absorption coefficient and z is the propagation distance.)
The condition that more than half of the light is absorbed by the light scattering member 13 can be expressed by the following formula (7).

When the above equation (7) is modified, the following equation (8) is obtained.

  The length L1 of the light scattering member 13 needs to satisfy the above formula (8), and thus formula (2) is derived.

  Next, light rays from the LED light source 11 will be described with reference to FIG. FIG. 7 is substantially similar to FIG. 6 except that the ray 20 is shown. The light beam 20 from the LED light source 11 passes through the edge of the bottom surface of the light scattering member 13, is totally reflected by the side surface of the transparent member 12, and then reaches the light scattering member 13.

If the light beam 20 is transmitted without being totally reflected by the side surface of the transparent member 12 parallel to the axis of symmetry, only the blue light from the LED light source 11 is emitted in this direction. It is considered that the light beam 20 hits the light scattering member 13 containing yellow phosphor particles, whereby the blue light from the LED light source 11 and the yellow light from the phosphor particles are mixed to easily become white light. Moreover, a wide light distribution angle can be achieved by being sufficiently scattered by the light scattering member 13. In particular, when white particles are encapsulated as the axially symmetric light scattering member 13, this effect is important. In order to satisfy these conditions, it is necessary to satisfy the relationship represented by the following formula (9).

This is expressed by the following formula (3) when the above formula (A) is used.

In addition, in order that the light beam 20 passes through the edge of the bottom surface of the light scattering member 13 and is totally reflected by the side surface parallel to the symmetry axis of the transparent member 12 and hits the light scattering member 13, the relationship represented by the following formula (4): It is necessary to satisfy.

  By satisfying the above-described conditions, the effect of remote phosphor can be obtained. Moreover, white light is generated by appropriately mixing blue light and yellow light. At the same time, wide light distribution by wide diffusion can be realized. This effect is important when the phosphor is white particles.

  ZEMAX ray tracing was performed on this embodiment. ZEMAX is described in, for example, (Radiant Zemax homepage, “http://www.radiantzemax.com/en/rz/”). As a result, in this embodiment, the light returning to the LED light source 11 was about 10%, and it was confirmed that the loss was lower than the conventional 40 to 60%. This can simultaneously suppress the heat generation of the blue LED chip as the LED light source 11 due to the absorption of the return light. That is, it was shown that the heat generation was low.

When an LED light source having a side of 1 mm is used, the LED illumination device of this embodiment fits in a cylinder having a diameter of 3 mm and a height of 7 mm. That is, in FIG. 5, it can be made into a cylindrical shape with d ₀ = 3 mm and L ₀ = 7 mm. It can be seen that the LED lighting device of the present embodiment is compact when compared to a conventional LED lighting device using an LED light source of a similar size of 10 to 20 mm.

  As described above, according to the present embodiment, a compact LED lighting device with low loss and low heat generation can be realized.

  FIG. 8 is a schematic diagram illustrating a cross-sectional configuration of an LED lighting device according to another embodiment. The LED lighting device 10 ″ shown in the figure is the same as the structure shown in FIG. 6 except that it has an air layer 15 in contact with the bottom surface of the light scattering member 13. In the transparent member 12, there is yellow light emitted from the light scattering member 13 and returning to the LED light source 11. However, by providing the air layer 15 in this way, such yellow light is reflected by total reflection, and return light can be reduced.

  In the light scattering member 13, a distribution can be provided in the concentration of the phosphor particles. Specifically, by increasing the concentration of the phosphor particles toward the upper side, yellow light is emitted further upward. At this time, more blue light is scattered. As a result, the effectiveness of the remote phosphor is further enhanced.

  The same effect can be obtained when the occupied sectional area of the phosphor particles in the light scattering member is increased toward the upper side. For example, such a structure can be obtained by forming the light scattering member into the following shape. Specifically, the diameter of the light scattering member is minimized at the bottom surface, and a portion where the diameter increases upward is provided, for example, the light scattering member 13 shown in FIG.

  FIG. 9 is a schematic diagram illustrating a cross-sectional configuration of an LED lighting device according to another embodiment. The LED light emitting device 10 ′ ″ shown in the figure is the same as the structure shown in FIG. 6 except that the end portions of the upper surface and the lower surface of the transparent member 12 ′ are curved.

Here, the z-axis is taken along the light distribution symmetry axis ax, and the upward direction is the positive direction. The origin is the point where the center of the light emitting surface of the LED light source 11 and the light distribution symmetry axis ax intersect. At this time, the cylindrical coordinates are (ρ _r , ρ _h ). That is, the radius of the column is ρ _r and the height is ρ _h .
At this time, the curve at the end of the upper surface satisfies the relationship represented by the following formula (11).

On the other hand, the curve at the end of the lower surface satisfies the relationship expressed by the following equations (12) and (13) with Θ (interval from 0 to π / 2) as a parameter.

The above-described relationship is, for example, Julio Chaves, “Introduction”.
to Nonimaging Optics ", CRC Press, 2008.

  The effect of the LED lighting apparatus of this embodiment is demonstrated as follows.

  By making the end of the upper surface of the transparent member 12 a curved surface, the direct light from the LED light source 11 is totally reflected and strikes the light scattering member 13. On the other hand, the light scattered from the light scattering member 13 is not totally reflected but is transmitted through the curved surface. That is, the direct light is once converted into scattered light by the light scattering member 13, and the scattered light is emitted to the outside. On the other hand, by making the end of the lower surface of the transparent member 12 a curved surface, the blue light that is transmitted without being totally reflected is reduced. As a result, blue light and yellow light from the LED light source 11 are appropriately mixed.

  The axially symmetric transparent member 12 in the LED lighting device shown in FIG. 9 can be composed of two types of transparent members having different refractive indexes. The LED lighting device 10 ″ ″ shown in FIG. 10 includes a transparent member 12 including a high refractive index transparent member 12a and a low refractive index transparent member 12b provided on the outside thereof. For example, transparent ceramic can be used for the high refractive index transparent member 12a, and PMMA can be used for the low refractive index transparent member 12b.

  Since the low refractive index transparent member 12b exists outside the high refractive index transparent member 12a, total reflection occurs at the interface between the inner side and the outer side, and the light from the LED light source 11 is guided to the axisymmetric light scattering member 13. . On the other hand, the light emitted and reflected from the light scattering member 13 is likely to exit to the outside because the low refractive index transparent member 12b exists in the surroundings.

  By setting it as such a structure, it becomes possible to guide the light from LED light source 11 to the light-scattering member 13, and to extract the light from the light-scattering member 13 to the exterior more efficiently.

  FIG. 11 is a schematic diagram illustrating a cross-sectional configuration of an LED lighting device according to another embodiment. The LED illumination device 10 ′ ″ ″ shown in the figure is the same as the structure shown in FIG. 9 except that the transparent member 12 ′ has two types of axially symmetric fluorescent layers.

  The first axisymmetric fluorescent layer 21 is provided in the axisymmetric transparent member 12 ′ so as to be separated from the LED light source 11. Further, a second axisymmetric fluorescent layer 22 is provided apart from the first axisymmetric fluorescent layer 21. The first and second axially symmetric fluorescent layers have a symmetry axis that substantially coincides with the light distribution symmetry axis ax. The first axisymmetric fluorescent layer 21 contains red phosphor particles, absorbs blue light, and emits red light. On the other hand, the second axisymmetric fluorescent layer 22 contains yellow phosphor particles, and absorbs blue light and emits yellow light.

The closest distance L ₂ between the LED light source 11 and the first axisymmetric fluorescent layer 21 satisfies the relationship represented by the formula (1) as described above.

In FIG. 11, the area S ₁ of the upper surface of the first axially symmetric fluorescent layer 21 is 1.66 mm ² , and the closest distance L between the first axially symmetric fluorescent layer 21 and the second axially symmetric fluorescent layer 22. _{If 4} is 2 mm, the relationship represented by the following formula (21) is satisfied.

  The effect of the LED lighting apparatus of this embodiment is demonstrated as follows.

  The first axisymmetric fluorescent layer 21 containing red phosphor particles also absorbs yellow light. On the other hand, the second axisymmetric fluorescent layer 22 containing yellow fluorescent agent particles does not absorb red light. Therefore, the red light is not absorbed by the second axisymmetric fluorescent layer 22 but is scattered in the transparent member 12 ′ and escapes upward. Thereby, the loss (the loss of the conventional device) that yellow light is absorbed by the first axisymmetric fluorescent layer 21 can be reduced.

  Moreover, the remote phosphor effect is enhanced by sufficiently separating the first axially symmetric fluorescent layer 21 containing red phosphor particles and the second axially symmetric fluorescent layer 22 containing yellow phosphor particles. As a result, the loss of yellow light absorbed by the first axisymmetric fluorescent layer 21 containing red phosphor particles (loss of the conventional device) can also be reduced.

  FIG. 12 is a perspective view illustrating a configuration of an LED lightening device according to another embodiment. The LED lighting device 10 '' '' '' shown in the figure has a heat dissipation housing 31 inside an axially symmetric scatterer 13 'and an axially symmetric transparent member 12' ', and further includes a power supply circuit 32 and wiring 33 therein. The structure is the same as that shown in FIG. However, as the LED light source 11 ′, a plurality of LEDs having a rectangular light emitting surface are arranged symmetrically about the light distribution symmetry axis ax. The distance RR is equidistant from the light distribution symmetry axis to the center of the light emitting surface of each LED light source.

  The heat dissipation housing 31 is made of metal, and can be configured using, for example, aluminum or copper. A cavity may be provided inside the housing, and a power supply circuit may be disposed in the cavity. As a result, heat generated from the LED and the power supply circuit is transmitted from the metal casing to the axially symmetric transparent member 12 and is radiated to the outside, thereby improving the heat dissipation characteristics. Further, since the power supply circuit is provided inside the metal casing, the entire lighting device can be made compact.

  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 spirit 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.

The invention described in the scope of claims at the time of the patent assessment of the original application of the present application will be appended below.
[1]
An LED light source having a light emitting surface of area C and having a light distribution substantially symmetric about a light distribution symmetry axis substantially perpendicular to the light emitting surface;
Visible light provided over the light emitting surface of the LED light source, having a first symmetry axis substantially coincident with the light distribution symmetry axis of the LED light source, and symmetric with respect to the first symmetry axis An axially symmetric transparent member transparent to
A bottom surface opposite to the light emitting surface, having a second symmetry axis that is spaced from the LED light source and is disposed inside the axially symmetric transparent member, substantially coincides with the light distribution symmetry axis of the LED light source. a LED lighting anda axisymmetric light scattering member is symmetrical with respect to with a length L ₁ along a diameter d ₁ and the second symmetry axis and the second axis of symmetry,
The closest distance L ₂ between the LED light source and the axisymmetric light scattering member and the area C of the light emitting surface of the LED light source satisfy the relationship represented by the following formula (1):
The length L ₁ of the axisymmetric light scattering member along the second symmetry axis and the coefficient μ (1 / mm) satisfy the relationship of the following formula (2):
The diameter d ₁ of the bottom surface of the axisymmetric light scattering member, the closest distance L _2, and the refractive index n of the axisymmetric transparent member satisfy the relationship of the following formula (3):
A surface obtained by projecting the axially symmetric transparent member onto a plane including the light emitting surface of the LED light source is an LED illumination device including the light emitting surface of the LED light source.
[2]
The LED illumination device according to [1], wherein the axially symmetric transparent member has a cylindrical shape.
[3]
The LED lighting device according to [2], which satisfies a relationship of the following formula (4).
(Where d ₀ is the diameter of the axisymmetric transparent member, d ₁ is the diameter of the bottom surface of the axisymmetric light scattering member, and L ₁ is the axisymmetric light along the second symmetry axis. The length of the scattering member, and L ₂ is the closest distance between the light emitting surface of the LED light source and the axisymmetric light scattering member.)
[4]
The LED illuminating device according to any one of [1] to [3], wherein the axially symmetric light scattering member has a cylindrical shape.
[5]
An axisymmetric air layer in contact with the bottom surface of the axisymmetric light scattering member;
The axisymmetric air layer is
A third axis of symmetry substantially coinciding with the light distribution symmetry axis of the LED light source;
Symmetric with respect to the third axis of symmetry;
The LED lighting device according to any one of [1] to [4].
[6]
The axisymmetric light scattering member according to [1] or [2], wherein the diameter of the bottom surface is the smallest and the diameter increases upward.
[7]
The said axially symmetric transparent member is the LED illumination device according to any one of [1], [4] to [6], wherein the diameter of the upper surface is the smallest and the diameter increases in a downward direction.
[8]
An LED light source having a light emitting surface with an area C and a light distribution symmetry axis substantially perpendicular to the light emission surface, and having a light distribution substantially symmetric about the light distribution symmetry axis;
Visible light is provided to cover the LED light source, and has a first symmetry axis that substantially coincides with the light distribution symmetry axis of the LED light source, and is symmetric with respect to the first symmetry axis. An axisymmetric transparent member that is transparent,
Disposed from the LED light source and disposed inside the axisymmetric transparent member, partially absorbs light from the LED light source, and emits first light in a visible region on a longer wavelength side than the light from the LED light source. A first axisymmetric fluorescence that has a second axis of symmetry substantially coincident with the light distribution symmetry axis of the LED light source and is symmetric with respect to the second axis of symmetry with an upper surface of area S ₁ Layers,
The first axisymmetric fluorescent layer is spaced above the first axisymmetric transparent member and partially absorbs light from the LED light source and has a wavelength longer than that of the light from the LED light source. LED lighting comprising: a second axisymmetric fluorescent layer that emits second light having a shorter wavelength than the first light and has a third axis of symmetry substantially coincident with the light distribution symmetry axis of the LED light source A device,
The closest distance L ₂ between the LED light source and the first axisymmetric fluorescent layer and the area C of the light emitting surface of the LED light source satisfy the relationship represented by the following formula (1):
The closest distance L ₄ between the first axisymmetric phosphor layer and the second axisymmetric phosphor layer and the area S ₁ of the upper surface of the first axisymmetric phosphor layer are expressed by the following formula (21). An LED lighting device that satisfies the relationship represented.
[9]
The LED illumination device according to any one of [1] to [8], wherein the LED light source emits monochromatic light having a peak wavelength of 390 to 460 nm.
[10]
The LED illumination device according to any one of [1] to [9], further including a substrate on which the LED light source is mounted and has a mounting surface that diffusely reflects visible light.
[11]
The LED illumination device according to any one of [1] to [9], further including a substrate on which the LED light source is mounted and has a mounting surface transparent to visible light.
[12]
The said axially symmetric transparent member is an LED illuminating device in any one of [2] thru | or [11] which has the curved surface represented by following formula (12) and Formula (13) in the edge part of a bottom face.
(here,
ρ _r and ρ _h are the radius and height, respectively, in cylindrical coordinates symmetric about the z axis,
The z axis is the positive direction upward with the intersection of the light distribution symmetry axis and the light emitting surface as the origin,
C is the area of the light emitting surface of the LED light source,
Θ is an interval of a parametric variable (0 <Θ <π / 2). )
[13]
A plurality of the LED light sources are mounted on the substrate and are equidistant RR from the light distribution symmetry axis to the center of the light emitting surface of each LED light source,
An axially symmetric heat transfer member that simultaneously penetrates the inside of the axially symmetric light scattering member and the inside of the axially symmetric transparent member;
The heat transfer member has a maximum diameter equal to or less than the RR, and is thermally bonded to the LED light source or the substrate.
[10] The LED lighting device according to any one of [11] or [12] subordinate to [11].

10, 10 ′, 10 ″, 10 ′ ″, 10 ″ ″, 10 ′ ″ ″... LED lighting device 10 ″ ″ ″... LED lighting device; 11, 11 ′. , 12 ', 12''... Axisymmetric transparent member; 12a ... High refractive index transparent member 12b ... Low refractive index transparent member; 13, 13' ... Axisymmetric light scattering member; 14 ... Substrate 15 ... Air layer; ; symmetrical L ₀ ... axisymmetric transparent member; 21 ... first axially symmetric fluorescent layer 22 ... second axisymmetric fluorescent layer; ax ... light distribution symmetry axis; 31 ... radiator enclosure 32 ... power supply circuit; 33 ... wire Length along the axis L ₁ ... Length along the axis of symmetry of the axisymmetric light scattering member L ₂ ... Distance closest to the axisymmetric light scattering member and the LED light source; L ₃ ... Thickness of the LED light source L ₄ ... The closest distance between the first axisymmetric fluorescent layer and the second axisymmetric fluorescent layer d ₀ ... diameter of the axisymmetric transparent member; d ₁ ... diameter of the axisymmetric light scattering member.

Claims (15)

An LED light source having a light emitting surface with an area C and having a light distribution that is substantially symmetric about a light distribution symmetry axis intersecting the light emitting surface;
A transparent member provided to cover the light emitting surface of the LED light source and substantially symmetric with respect to the light distribution symmetry axis of the LED light source;
A light scattering member disposed inside the transparent member and having a diameter d _{1 of} a bottom surface facing the light emitting surface and a length L ₁ along the light distribution symmetry axis, and substantially symmetric with respect to the light distribution symmetry axis; An LED lighting device comprising:
The distance L ₂ between the LED light source and the light scattering member and the area C of the light emitting surface of the LED light source satisfy the relationship represented by the following formula (1),
The length L ₁ of the light scattering member and the coefficient μ (1 / mm) satisfy the relationship of the following formula (2),
The diameter d ₁ of the bottom surface of the light scattering member, the distance L _2, and the refractive index n of the transparent member satisfy the relationship of the following formula (3).
  The LED lighting device according to claim 1, wherein the transparent member has a cylindrical shape. The LED lighting device according to claim 2, satisfying a relationship of the following formula (4).
(Where d ₀ is the diameter of the transparent member, d ₁ is the diameter of the bottom surface of the light scattering member, and L ₁ is the length of the light scattering member along the light distribution symmetry axis). , L ₂ is the distance between the light emitting surface of the LED light source and the light scattering member.)   The LED lighting device according to claim 1, wherein the light scattering member has a cylindrical shape. An axisymmetric air layer in contact with the bottom surface of the light scattering member;
The axisymmetric air layer is substantially symmetric with respect to the light distribution symmetry axis.
The LED lighting device according to claim 1.   3. The LED lighting device according to claim 1, wherein the light scattering member has a portion having a minimum bottom surface diameter and a portion in which the diameter increases upward.   The LED lighting device according to claim 1, wherein the transparent member has a portion having a minimum diameter on an upper surface and the diameter increasing downward.   The LED lighting device according to claim 1, further comprising a substrate on which the LED light source is mounted and has a mounting surface that diffusely reflects visible light.   The LED illumination device according to claim 1, further comprising a substrate on which the LED light source is mounted and has a mounting surface that is transparent to visible light. 10. The LED lighting device according to claim 2, wherein the transparent member has a curved surface represented by the following formula (12) and formula (13) at an end portion of a bottom surface.
(here,
ρ _r and ρ _h are the radius and height, respectively, in cylindrical coordinates symmetric about the z axis,
The z axis is the positive direction upward with the intersection of the light distribution symmetry axis and the light emitting surface as the origin,
C is the area of the light emitting surface of the LED light source,
Θ is an interval of a parametric variable (0 <Θ <π / 2). ) A plurality of the LED light sources are mounted on the substrate and are equidistant RR from the light distribution symmetry axis to the center of the light emitting surface of each LED light source,
An axisymmetric heat transfer member that passes through the light scattering member and the transparent member at the same time;
The heat transfer member has a maximum diameter equal to or less than the RR, and is thermally bonded to the LED light source or the substrate.
The LED illumination device according to claim 8 or 9. The LED light source has a light emitting surface with an area C, and is provided to cover the light emitting surface of the LED light source having a substantially symmetrical light distribution around a light distribution symmetry axis intersecting the light emitting surface. A transparent member that is substantially symmetrical about the axis;
A light scattering member disposed inside the transparent member and having a diameter d _{1 of} a bottom surface facing the light emitting surface and a length L ₁ along the light distribution symmetry axis, and substantially symmetric with respect to the light distribution symmetry axis; A light guide member comprising:
The distance L ₂ between the LED light source and the light scattering member and the area C of the light emitting surface of the LED light source satisfy the relationship represented by the following formula (1),
The length L ₁ of the light scattering member and the coefficient μ (1 / mm) satisfy the relationship of the following formula (2),
The diameter d ₁ of the bottom surface of the light scattering member, the distance L _2, and the refractive index n of the transparent member satisfy the relationship of the following formula (3).
A transparent member having an incident surface on which light is incident, and an outer peripheral surface extending in a direction intersecting the incident surface from an outer peripheral edge of the incident surface;
A light scattering member that is disposed inside the transparent member and scatters light incident on the transparent member through the incident surface;
The light guide member including an inclined surface that has an area in which the outer peripheral surface of the transparent member surrounds the light scattering member and is inclined inward as the area moves away from the incident surface.   The light guide member according to claim 13, wherein the light scattering member has an interface extending in a direction intersecting the incident surface between the light scattering member and the transparent member.   The inclined surface of the transparent member includes a first inclined surface that is close to the incident surface, and a second inclined surface that is inclined further inward than the first inclined surface continuously to a side farther from the incident surface of the first inclined surface. The light guide member according to claim 13, comprising a surface.