WO2016052025A1

WO2016052025A1 - Led module and lighting apparatus

Info

Publication number: WO2016052025A1
Application number: PCT/JP2015/074266
Authority: WO
Inventors: 弘康近藤; 亮二津田; 大野　博司; 光章加藤; 久野　勝美
Original assignee: 株式会社東芝; 東芝マテリアル株式会社
Priority date: 2014-09-30
Filing date: 2015-08-27
Publication date: 2016-04-07
Also published as: JPWO2016052025A1; JP6293914B2

Abstract

　An LED module is provided with: a plurality of LED light sources, each having a light-emitting surface included in the same plane, and each emitting from the light-emitting surface light having a different light-emission spectrum in the visible-light region; axially symmetric transparent members formed with axial symmetry around a light-distribution symmetry axis that is substantially orthogonal to the plane, the transparent members covering the light-emitting surfaces of the plurality of LED light sources and guiding the light emitted from the plurality of LED light sources; and axially symmetric light-scattering members for scattering the light guided by the axially symmetrical transparent members, said axially symmetric light-scattering members formed with axial symmetry around the light-distribution symmetry axis, positioned apart from the plurality of LED light sources, and provided on the interior of the axially symmetrical transparent members. The projection images of the axially symmetric light-scattering members that are projected parallel to the plane overlap at least some of the light-emitting surfaces of the plurality of LED light sources.

Description

LED module and lighting device

Embodiments of the present invention relate to an LED module and a lighting device.

Recently, an illumination device (hereinafter, referred to as a white LED illumination device) including a white LED light source that obtains white light by combining a blue light emitting diode (LED) chip and a phosphor has become widespread. White LED lighting devices have various advantages such as less power consumption than conventional incandescent bulbs, but on the other hand, what is an incandescent bulb that emits light with a high blue light emission peak and shades close to natural light? It has quite different emission characteristics. For example, in an incandescent light bulb, when the brightness of the light bulb is adjusted to be dark, the color temperature decreases due to the light emission characteristics of the tungsten filament, and the light becomes white light with strong redness.

On the other hand, in the white LED lighting device, the brightness can be freely changed with white light having the same color temperature, but the color temperature cannot be changed according to the change in the brightness of the light. For example, even if the brightness of the white LED light source is adjusted to be dark, the color temperature hardly changes due to the light emission characteristics of the LED, and the emitted light remains white light with strong bluishness.

Japanese Patent No. 486098 Japanese Patent Laid-Open No. 10-242513

Incandescent light bulbs are naturally accepted by people around the world unconsciously because they emit light with a brightness and shade similar to natural light due to the light emission characteristics of the filament whose color temperature changes with brightness. Similarly, people in the world have a tendency to shine like incandescent bulbs (brightness of light and color of light) for white LED lighting devices.

In addition, humans have internal rhythms based on living in natural light, but because modern lifestyles have diversified lifestyles, human rhythms are disturbed by long hours of indoor work or day / night reversal work. It's getting easier. For this reason, from the viewpoint of safety and hygiene, there is a strong demand from the world for illumination light that shines closer to natural light than room lighting.

An object of the embodiment of the present invention is to provide an LED module and a lighting device that emit light like a filament light source of an incandescent bulb.

The LED modules according to the embodiments described herein each have a light emitting surface included in the same plane, and a plurality of LED light sources that respectively emit light having different emission spectra in the visible light region from the light emitting surface, Axisymmetric transparent member formed symmetrically about a light distribution symmetry axis substantially orthogonal to the plane, covering the light emitting surface of the plurality of LED light sources, and guiding light emitted from the plurality of LED light sources And axisymmetrically formed around the light distribution symmetry axis, located apart from the plurality of LED light sources, provided inside the axially symmetric transparent member, and scattering light guided by the axially symmetric transparent member And the projected image of the axially symmetric light scattering member projected in parallel on the plane overlaps at least a part of each light emitting surface of the plurality of LED light sources.

FIG. 1 is a side view showing an illumination apparatus according to an embodiment. FIG. 2 is a perspective cross-sectional view illustrating the illumination device of the embodiment. FIG. 3 is a perspective view showing the LED module of the embodiment. FIG. 4 is an enlarged schematic side view showing the LED module of the embodiment. FIG. 5 is an enlarged schematic side view showing an outline of an attachment mechanism for attaching the light guide to a chip-on-board (hereinafter referred to as “COB”). FIG. 6 is an enlarged side schematic view showing an outline of an attachment mechanism for attaching the light guide to the COB. FIG. 7A is a schematic side view illustrating an example of a trajectory of light in the light guide. FIG. 7B is a schematic side view showing an example of the locus of light in the light guide. FIG. 7C is a schematic side view illustrating an example of a locus of light in the light guide. FIG. 7D is a schematic side view showing an example of the locus of light in the light guide. FIG. 8 is a schematic longitudinal sectional view showing an outline of the LED module. FIG. 9 is a schematic vertical sectional view of a plurality of combination LED light sources. FIG. 10 is a schematic plan view of a plurality of combination LED light sources. FIG. 11 is a parallel projection diagram schematically showing a projection image of a light scattering member projected on the light emitting surface of a plurality of combination LED light sources. FIG. 12A is a plan view showing a projected image of a light scattering member projected on the light emitting surface of another multiple combination LED light source. FIG. 12B is a plan view showing a projected image of the light scattering member projected onto the light emitting surface of another multiple combination LED light source. FIG. 12C is a plan view showing a projected image of the light scattering member projected onto the light emitting surface of another multiple combination LED light source. FIG. 12D is a plan view showing a projected image of the light scattering member projected on the light emitting surface of another multiple combination LED light source. FIG. 12E is a plan view showing a projected image of the light scattering member projected onto the light emitting surface of another multiple combination LED light source. FIG. 12F is a plan view showing a projected image of the light scattering member projected onto the light emitting surface of another multiple combination LED light source. FIG. 13 is a schematic cross-sectional view showing an enlarged part of a plurality of combination phosphor layers partitioned by high barrier ribs. FIG. 14 is a schematic cross-sectional view showing an enlarged part of a plurality of combination phosphor layers partitioned by low barrier ribs. FIG. 15 is a circuit diagram of a multiple combination LED light source of the embodiment. FIG. 16 is a characteristic diagram showing current-voltage characteristics of a single white LED light source and three types of combination white LED lighting devices. FIG. 17 is a characteristic diagram showing the relationship between total luminous flux and input current in three types of combination white LED lighting devices. FIG. 18 is a characteristic diagram showing the relationship between color temperature and total luminous flux by comparing three types of combination white LED lighting devices and incandescent bulbs. FIG. 19 is a circuit diagram of various white LED lighting devices having a single color temperature. FIG. 20 is a characteristic diagram showing current-voltage characteristics of various white LED lighting devices having a single color temperature. FIG. 21 is a circuit diagram of a multiple combination white LED lighting device according to another embodiment. FIG. 22 is a characteristic diagram showing current-voltage characteristics of a plurality of combination white LED lighting devices in which different color temperatures are combined. FIG. 23 is a characteristic diagram showing the relationship between the current (partial current) flowing in each area and the input current (total current) in two types of combination white LED light sources. FIG. 24 is a characteristic diagram showing the relationship between total luminous flux and input current in two types of combination white LED light sources. FIG. 25 is a characteristic diagram showing a comparison between two types of combination white LED light sources and incandescent bulbs regarding the relationship between color temperature and total luminous flux.

Hereinafter, some embodiments will be described with reference to the accompanying drawings.

As shown in FIGS. 1 and 2, the lighting device 1 of the embodiment is formed in a shape and size that approximates an incandescent bulb. Such an illuminating device 1 is formed by inserting the LED module 10 in a globe 2 made of spherical glass and sealing the opening of the globe 2 with a base 3.

The LED module 10 has a plurality of

LED light sources

13a, 13b, 13c having a light emitting surface 18 included on the same plane. The plurality of

LED light sources

13a, 13b, and 13c are mounted on the same substrate 11 using COB technology, and are supported by the substrate 11 by a cylindrical heat sink 4 having a hollow portion 4c.

The heat sink 4 is made of a metal material having excellent thermal conductivity such as aluminum or aluminum alloy. An annular protrusion is formed on the base end portion 4 b of the heat sink 4. The heat sink 4 is fixed to the base 3 by caulking the base 3 to the annular protrusion.

On the other hand, the front end portion 4a of the heat sink 4 supports the axially symmetric transparent member 14 via the lens presser 6 having a perforated cap shape. A reduced diameter portion slightly smaller than the diameter of the heat sink body is formed at the heat sink tip 4a. The substrate 11 is fastened with a plurality of screws 5 to the upper end of the reduced diameter portion 4a. The lens retainer 6 is put on the outer periphery of the heat sink diameter-reduced portion 4a. The transparent member 14 is inserted into the opening of the lens holder 6 and joined to the light emitting surface 18 of the LED light source 13. The support structure for supporting the transparent member 14 by the lens presser 6 is reinforced.

A lighting circuit 42 is provided in the hollow portion 4 c of the heat sink 4. The lighting circuit 42 is connected to both poles of the base 3 by internal wiring. The lighting circuit 42 is connected to the light emitting circuits of the

light sources

13a, 13b, and 13c on the substrate 11, respectively, as shown in FIGS. The lighting circuit 42 has an AC / DC conversion function for converting alternating current into direct current and a lighting function for supplying power to the light emitting circuit and causing the

light sources

13a, 13b, and 13c to emit light.

Next, the LED module 10 will be described in detail with reference to FIGS. 3 to 10 and FIG.

The LED module 10 of the embodiment is a combination of three

LED light sources

13a, 13b, 13c, an axially symmetric transparent member 14, and an axially symmetric light scattering member 15. Each

LED light source

13a, 13b, 13c includes a plurality of LED chips (not shown) and a phosphor layer 12 covering the plurality of LED chips. The LED chip is incorporated in a circuit board 11C in which an LED light emitting circuit is formed on an alumina substrate by a chip-on-board technique, for example. On the circuit board 11C, for example, a light emitting circuit including three

LED chip groups

13a, 13b, and 13c shown in FIG. 15 is mounted. Further, the LED chip group circuit board 11C is mounted on a common circuit board 11B as shown in FIG. The phosphor layer 12 on the substrate 11C provides a light emitting surface 18 that emits white light. As will be described later, the phosphor layer 12 is formed by applying phosphor materials having different color temperatures for each divided area as shown in FIGS. 9 to 14, for example.

The axisymmetric light transparent member 14 is attached to the common substrate 11B so as to cover all of the light emitting surfaces 18 of the plurality of light sources. The axially symmetric light transparent member 14 has a cylindrical shape as a whole, and is substantially axially symmetric with respect to the light distribution symmetry axis ax. Similarly, the axially symmetric light scattering member 15 is also substantially axially symmetric with respect to the light distribution symmetry axis ax. The transparent member 14 is solid at the proximal end side and is hollow at the distal end side. A coating film containing the light scattering particles 17 is formed on the inner surface of the hollow portion 14h of the transparent member. The coating film containing the light scattering particles 17 constitutes the light scattering member 15.

As shown in FIG. 4, the axially symmetric transparent member 14 has an outer diameter that gradually decreases from the proximal end side toward the distal end side along the Z axis. That is, in the axisymmetric transparent member 14, the frustoconical first intermediate portion 14b has a smaller outer diameter than the cylindrical base end portion 14a, and the second intermediate portion 14c has a smaller outer diameter than the first intermediate portion 14b. The outer diameter is even smaller, and the outer diameter of the tip portion 14d is smaller than that of the second intermediate portion 14c.

Contrary to this, the diameter of the hollow portion 14h of the transparent member gradually increases from the proximal end side to the distal end side of the transparent member 14, and therefore the inner diameter of the light scattering member 15 also increases. That is, in the axially symmetric transparent member 14, the inner diameter of the first intermediate portion 14m is larger than the bottom surface 14n on the base end side, and the inner diameter of the second intermediate portion 14l is larger than that of the first intermediate portion 14m. The inner diameter of the third intermediate portion 14k is larger than that of the second intermediate portion 14l, and the inner diameter of the distal end portion 14j is further increased than that of the third intermediate portion 14k.

The taper angles of these

portions

14a, 14b, 14c, 14d, 14j, 14k, 14l, 14m, and 14n can be determined using the optical characteristics and analysis method of the entire LED module. Specifically, the thickness of the transparent member 14 surrounding the light scattering member 15 gradually decreases as it moves from the proximal end side to the distal end side of the transparent member 14, and as a result, a thickness changing portion 16 is formed. ing. Such a thickness changing portion 16 has a lens function or a light collecting function for collecting a plurality of lights in a specific focal region (hereinafter referred to as a virtual light source region). As shown in FIGS. 7A to 7D, the light is guided by the transparent member 14, and the light reaching the light scattering member 15 is repeatedly reflected and scattered in the light scattering member 15, so that the entire surface of the light scattering member 15 emits light. Looks like. The light traveling from the light scattering member 15 toward the tip side is emitted from the module 10 to the outside as it is. On the other hand, the light traveling from the light scattering member 15 toward the side surface 14s or the base end side is condensed by the thickness changing portion 16 onto the bottom surface 14n of the hollow portion as the virtual light source region. As a result of the light concentration toward the bottom surface 14n of the hollow portion, it looks to the external observer as if light is emitted from the bottom surface 14n of the hollow portion.

The lighting device 1 of the present embodiment is designed so that the bottom surface 14n of the hollow portion serving as the virtual light source region is positioned at the substantially center of the globe 2, so that the lighting device 1 emits light in the same manner as a filament light-emitting incandescent bulb. Become.

The assembly method of the LED module 10 will be described with reference to FIGS.

First, the base end surface of the transparent member 14 is bonded and fixed to the circuit board 11C of the light source with an adhesive. When the lens holder 6 is put on the fixed transparent member 14, the lower protrusion 14p of the transparent member is fitted into the lens holder groove 6g, and the lens holder 6 is positioned with respect to the substrate 11B. As a result, the screw hole 6a for the lens retainer and the screw hole 11a for the substrate communicate with each other. When the screw 5 is screwed into the screw holes 6a and 11a that communicate with each other, the LED light source 13 is firmly fastened to the reduced diameter portion of the heat sink 4 together with the lens holder 6 with the screw 5.

The LED light source 13 includes a plurality of light emitting elements that emit light in the visible light region, and has a flat light emitting surface 18. As the light emitting element, for example, an LED chip that emits monochromatic light having a peak wavelength in the range of 350 to 470 nm can be used. Specifically, for example, a purple LED chip that emits light having a peak wavelength of 410 nm can be used. A phosphor layer 12 is applied and formed so as to cover such an LED chip. The phosphor layer 12 absorbs primary light from the LED chip, converts the wavelength of light, and emits secondary light. The area where the phosphor layer 12 is applied provides the light emitting surface 18 of the light source.

In the present embodiment, the light distribution from the LED chip has a light distribution symmetry axis ax, and is a distribution close to symmetry with respect to the light distribution symmetry axis ax. As the light distribution, for example, Lambertian can be used, but is not limited to this, and other distributions may be used. The light distribution symmetry axis ax can pass, for example, near the center in the light emitting surface of the LED chip, but is not limited to this, and other points in the same plane as the light emitting surface 18 of the LED chip are not limited thereto. You can pass.

The LED light source 13 may be placed on the substrate 11 as necessary. The substrate 11 is not particularly limited, but the substrate mounting surface can be made of a material that 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 transparent material which can permeate | transmit visible light. Also in this case, the transmitted light passing through the substrate 11 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 14 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. As the inorganic material, for example, glass and transparent ceramics can be used. As the organic material, for example, a transparent resin selected from the group consisting of acrylic resin, silicone resin, epoxy resin, polycarbonate, polyethylene terephthalate (PET) resin, and polymethyl methacrylate (PMMA) resin can be used. Here, the transparent means that visible light can be transmitted. The refractive index n of the transparent member and the total reflection angle θc have the relationship of the following formula (A).

The axially symmetric light scattering member 15 is disposed inside the axially symmetric transparent member 14 and contains light scattering particles 17 that scatter white light from the LED light source 13. The light scattering particles 17 are preferably white particles such as a white pigment that totally reflects light.

The outline of the method for producing the axially symmetric transparent member 14 and the axially symmetric light scattering member 15 will be described.

A transparent resin is injection molded by an injection molding machine to form a cylindrical axisymmetric transparent member 14. Next, the white particles 17 are mixed and stirred in the transparent binder to prepare a mixture slurry in which the white particles 17 are uniformly dispersed in the transparent binder. The mixture slurry is thinly applied to the peripheral wall of the hollow portion 14h of the axisymmetric transparent member by an application device. The average thickness of the coating layer is preferably in the range of 50 to 100 μm. The coating layer constitutes the axially symmetric light scattering member 15. The coating layer 15 covers the peripheral wall of the hollow portion 14h of the transparent member and scatters the light guided by the transparent member 14.

In addition, as a transparent binder for producing the light-scattering member containing particle | grains, it is not limited to what was mentioned above, It is transparent with respect to visible light, and if it is transparent resin which can hold | maintain a particle | grain inside Good.

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 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 given by the following equation (B).

In order to clarify the closest distance L ₂ between the light scattering member 15 and the LED light source 13, although for convenience the transparent member 14 in FIG. 4 is shown as not in contact with the substrate 11, in fact transparent The member 14 is in contact with the substrate 11.

The symmetry axis of the axially symmetric transparent member 14 substantially coincides with the light distribution symmetry axis ax of the LED light source 13, and the symmetry axis of the axially symmetric light scattering member 15 also substantially coincides with the light distribution symmetry axis ax. Yes. In addition, if the light distribution symmetry axis ax of the LED light source is within the range of product variation, it can be considered that the symmetry axes substantially coincide.

It is preferable that the closest distance L ₂ and the area C of the light emitting surface 18 satisfy the relationship of the following formula (1).

Further, it is preferable that the length L ₁ of the light scattering member and the absorption coefficient μ (1 / mm) of the light scattering member satisfy the relationship of the following formula (2).

Furthermore, it is preferable that 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 transparent member satisfy the relationship of the following formula (3).

When the length L ₁ and the absorption coefficient μ satisfy the relationship of the above equation (2), the light 8 emitted from the LED light source does not pass through the light scattering member 15 and leaks out from the lighting device 1 to the outside. Disappear.

Also, the following effect can be obtained by the relationship (3) above. The light 8 from the LED light source 13 is totally reflected by the side surface 14s of the transparent member except for part of the light scattered by the bottom surface 15e of the light scattering member, and is scattered by the respective portions 15a to 15d of the light scattering member. . In this way, since light is repeatedly reflected and scattered and then released to the outside, it appears to the external observer that the entire surface of the light scattering member 15 is emitting light.

The cross section orthogonal to the symmetry axis of the light scattering member 15 is included in the cross section of the transparent member 14 in the plane including the cross section. That is, the periphery of the light scattering member 15 is reliably covered with the transparent member 14 on a plane orthogonal to the symmetry axis. Further, the surface obtained by projecting the transparent member 14 in parallel to the light emitting surface 18 of the light source covers the entire light emitting surface 18. In other words, the cross section of the maximum diameter of the transparent member 14 is larger than the light emitting surface 18 of the light source.

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

The LED light source 13 is disposed on the alumina substrate 11 and is covered with a transparent member 14. The transparent member 14 has a cylindrical shape with the light distribution symmetry axis ax as the symmetry axis, and the bottom surface thereof is in contact with the substrate 11. In this embodiment, the transparent member 14 is produced using an acrylic resin (refractive index n = about 1.5).

The light scattering member 15 is a coating film having a light distribution symmetry axis ax as a symmetry axis, and is formed of a transparent resin including white particles 17 disposed inside the transparent member 14. The white particles 17 are uniformly dispersed in the transparent resin layer. The white particles 17 scatter the light 8 from the light source, and generate scattered light 9 directed in various directions with almost no light absorption. An absorption coefficient μ (1 / mm) of the light scattering member 15 including such white particles 17 is set to 0.1.

In the LED module of this embodiment, the area C of the light emitting surface 18 of the light source is, for example, 1 mm ² . When this value is substituted into the right side of Equation (1) and calculated, the value on the right side is about 0.28 mm.

The LED module of this embodiment, is set to the shortest distance L ₂ for example 3.0mm between the light source 13 and the light scattering member 15. Since the calculated value is smaller than 3.0 mm, the relationship of Expression (1) is satisfied.

In the LED module of the present embodiment, the absorption coefficient μ (1 / mm) of the light scattering member 15 is set to 0.1. If this value is substituted into the right side of Equation (2) and calculated, the value on the right side is 3.0.

In the LED module of this embodiment, the length L ₁ of the light scattering member 15 is set to 10.6 mm, for example. Since this is larger than the calculated value of 3.0 mm, the relationship of Expression (2) is satisfied.

When the closest distance L ₂ (= 14.8) and the refractive index n (= 1.5) are respectively substituted into the right side of the equation (3) and calculated, the value on the right side is about 33.

In the LED module of the present embodiment, the diameter d ₁ of the bottom surface 15e of the light scattering member is set to 7.6 mm, for example. Since the calculated value 33 is larger than the diameter d ₁ (= 7.6 mm), the relationship of the expression (3) is satisfied.

Further, it is preferable that the diameter d ₁ and the closest distance L ₂ of the light scattering member 15 satisfy the relationship of the following formula (4). In the LED module of the present embodiment, the diameter d ₀ of the transparent member 14 is 10.2 mm, for example. When the diameter d ₀ and the diameter d ₁ are substituted into the left side of Equation (4) and calculated, the value on the left side is about 0.745. Further, when the lengths L ₁ and L ₂ are substituted into the right side of the equation (4) and calculated, the value on the right side is about 0.736. These calculated values satisfy the relationship of equation (4).

In addition, the above-mentioned numerical value shows an example, and can be variously changed within a range that satisfies the above mathematical formula.

The operation of the lighting device of this embodiment will be described.

When the light 8 emitted from the LED light source 13 reaches the light scattering member 15, it hits the white particles 17 and is scattered. Part of the light from the LED light source 11 is scattered by the light scattering member 15 after repeating total reflection at the axially symmetric transparent member 12.

Part of the light from the bottom surface 15 e of the light scattering member closest to the LED light source 13 returns to the light source 13. The ratio is a solid angle in which the LED light source 13 is expected with respect to all solid angles with the light scattering member 15 as the center, and an approximate value can be obtained using the following equation (5).

The smaller the value of Equation (5), the less the return light from the light scattering member 15 to the light source 13. The value of formula (5) is preferably at least smaller than 1. Therefore, it is preferable to satisfy the relationship of the above formula (1).

In this embodiment, since C = 1 mm, the ratio of the return light obtained from this and the above equation (5) is about 0.8%.

Next, the process of light in the light transparent member 14 will be described with reference to FIGS. 7A to 7D. Each of FIGS. 7A to 7D has substantially the same configuration as that of FIG. 4 except for the travel of

light

8 and 9. Note that the process of the

linear light

8 and 9 entered in the drawing is convenient, and the actual light is emitted from the flat light source 13 in a planar shape.

The light 8 from the LED light source 13 is guided by the transparent member 14 and collected on the light scattering member 15 by the thickness changing portion 16 of the transparent member 14. For example, the light 8 directed from the light scattering member 15 toward the distal direction is collected by the light scattering member 15 as shown in FIGS. 7B, 7C, and 7D, respectively. The directed light 8 is guided toward the bottom surface 15e of the light scattering member by the thickness changing portion 16 of the transparent member while being reflected by the transparent member 14. As a result of the concentration of the light 8 toward the bottom surface 15e of the light scattering member in this way, the external observer looks as if light is emitted from the bottom surface 15e of the light scattering member.

Further, as shown in FIG. 7D, for example, the light 8 is totally reflected by the side surface 14s of the transparent member, passes through the vicinity of the edge of the bottom surface 15e of the light scattering member, and is totally reflected again by the side surface of the transparent member 14. The light scattering member 15 is reached. In this case, since the outer peripheral surface on the tip side of the transparent member 14 is tapered, the incident angle of the light 8 with respect to the side surface 14s of the transparent member is different between the first total reflection and the second total reflection. However, in the present embodiment, the LED module 10 is designed so that the light 8 incident at various incident angles is substantially totally reflected by the side surface 14s of the transparent member. There is no direct leakage outside.

If the light 8 emitted from the light source is transmitted without being totally reflected by the side surface 14s of the transparent member, the light 8 from the light source is emitted in this direction as it is without being scattered. Further, the LED light 8 that is not scattered has a strong directivity, so the irradiation range is narrow, and the surroundings are not illuminated in a wide range and evenly.

However, the LED module 10 of the present embodiment is designed to totally reflect the light 8 emitted from the light source 13 on the side surface 14s of the transmissive member. For example, in the LED module of the present embodiment, the maximum diameter d ₀ of the axisymmetric transparent member is 10.2 mm, the diameter d ₁ of the bottom surface of the axisymmetric light scattering member is 7.6 mm, the length L ₁ is 10.6 mm, and the length The length L _{2 is set} to 14.8 mm so that at least the expressions (1), (2), (3), and (4) are satisfied.

When the light 8 reaches the light scattering member 15, it hits the white particles 17 in the light scattering member 15, is scattered by the white particles 17, becomes scattered light 9, and goes out of the module. That is, since the peripheral wall surrounding the hollow portion 14h is covered with the light scattering member 15, scattering and reflection are repeated in the light scattering member 15, and the entire light scattering member 15 appears to emit light to the external observer. . In this case, the higher the concentration of the white particles 17 in the light scattering member 15, the more light 8 is scattered by the white particles 17, and when the white particle concentration exceeds a certain threshold, substantially all Light 8 becomes scattered light 9.

In addition, when the light scattering member 15 sufficiently scatters light, a wide light distribution angle can be achieved. In particular, when white particles are encapsulated as the light scattering member 15, this effect is important. In order to satisfy these conditions, it is desirable to satisfy the relationship represented by the following formula (6).

This is expressed by equation (3) using equation (A) described above.

In addition, in order for the light 8 to pass through the vicinity of the edge of the bottom surface 15e of the light scattering member and be totally reflected by the side surface 14s parallel to the symmetry axis of the transparent member 14 and hit the light scattering member 15, the relationship of Equation (4) is satisfied. It is desirable to satisfy. By satisfying the above conditions, wide light distribution by wide diffusion can be realized.

It should be noted that ZEMAX ray tracing was performed on the illumination device of the present embodiment. ZEMAX is described in detail, for example, on the homepage of Zemax (Radiant Zemax homepage; “http://www.radiantzemax.com/en/rz/”). As a result of carrying out ZEMAX, it was confirmed that the light returning to the LED light source 13 in this embodiment has a lower loss than the conventional 40 to 60%. This means that heat generation of the LED light source 13 due to absorption of return light can be suppressed. From this, it was also confirmed that the LED light source 13 of the present embodiment generates low heat.

Next, the LED light sources used for the LED modules and the illumination devices of various embodiments will be described in detail.

In the embodiment of the present invention, a plurality of LED light sources are arranged in combination so that the light emitting surfaces are included on the same plane, and white light having an emission spectrum with different color temperatures is emitted from each LED light source. Yes. However, since a plurality of LED light sources are arranged adjacent to each other, the primary light emitted from a certain light source is not absorbed only by the phosphor layer, but is easily absorbed by the phosphor layers of other light sources in the surroundings, and a predetermined color temperature There is a risk that the total luminous flux of the secondary light becomes lower than the target value of the total luminous flux. In particular, if the adjacent phosphor layers are in direct contact with each other, the primary light is easily absorbed by the adjacent phosphor layer, so that the total luminous flux of the obtained secondary light is significantly below the target specified value. There is.

Therefore, in the embodiment of the present invention, as shown in FIG. 9, FIG. 13 and FIG. 14, a high-reflectance barrier rib 20 is provided between adjacent phosphor layers, and one phosphor layer is separated by the barrier rib 20. The other phosphor layer is shielded from physical contact. Thus, the partition walls 20 that bring the adjacent phosphor layers into non-contact with each other prevent the primary light from one light source from being absorbed by the phosphor layer of the other light source, so that all of the target specified values can be obtained. Secondary light having a luminous flux is obtained.

In the embodiment of the present invention, for example, as shown in FIG. 11, the projected image 30 of the axially symmetric light scattering member 15 projected in parallel on the XY plane is at least one of the light emitting surfaces of the

LED light sources

13a, 13b, 13c. It overlaps with each part. The relative positional relationship between the

LED light sources

13a, 13b, and 13c and the axially symmetric light scattering member 15 is such that white light having different color temperatures emitted separately from the

light sources

13a, 13b, and 13c is efficient in the light scattering member 15. It comes to be mixed well, resulting in white light with a hue and brightness close to natural light.

In the embodiment of the present invention, in the light emitting circuit of each

LED light source

13a, 13b, 13c, a series circuit in which a plurality of

LED chips

24, 25, 26 are connected in series is formed, and a plurality of these series circuits are connected in parallel.

LED chip groups

21, 22, and 23 connected to are configured. Such

LED chip groups

21, 22, and 23 are circuits in which a plurality of LED chip series circuits are connected in parallel.

Furthermore, in the embodiment of the present invention, as shown in FIGS. 15 and 21, resistors R1 and R2 are inserted on the negative electrode side in the light emitting circuit of the light source having a low color temperature. When these insertion resistors R1 and R2 cause an inflection point in the current-voltage characteristic line of the light emitting circuit of the light source 13a having a high color temperature, and the input current is lowered to a point lower than the inflection point of the characteristic line, As shown in FIGS. 16 and 22, current flows preferentially to the light emitting circuit of the light source having a low color temperature. Thereby, as the brightness of the illumination light becomes darker, the hue of the light becomes reddish, and white light with a hue close to natural light can be obtained.

Hereinafter, a plurality of combined white LED light sources used in the LED module according to the first embodiment will be described in detail with reference to FIGS. 9 to 11 and 13 to 18.

(First embodiment)
The LED module 10 of the first embodiment includes three white LED

light sources

13a, 13b, and 13c. These three white LED

light sources

13a, 13b, and 13c are configured to emit white light having different emission spectra, that is, white light having different color temperatures. Among these, the first light source 13a is arranged in the central area of the light emitting surface 18, and the light emitting circuit having the first LED chip group 21 and the phosphor layer 12a so as to emit white light having the highest color temperature. Are combined. The second light source 13b is disposed in the right area of the light emitting surface 18 in the drawing, and the light emitting circuit and the phosphor having the second LED chip group 22 so as to emit white light having an intermediate color temperature. Combined with layer 12b. In addition, the third light source 13c is arranged in the left area of the light emitting surface 18 in the drawing, and the light emitting circuit and the phosphor having the third LED chip group 23 so as to emit white light having the lowest color temperature. Layer 12c is combined.

The LED light emitting circuits of the first to third

light sources

13a, 13b, and 13c have three circuit boards 11C using chip-on-board technology, as shown in FIGS. 9, 10, 13, and 14. It is mounted on a common circuit board 11B. Further,

LED chip groups

21, 22, and 23 are mounted on the three circuit boards 11C using chip-on-board technology.

The three types of

phosphor layers

12a, 12b, and 12c having different color temperatures are formed as follows.

As a phosphor mixture, four phosphor materials of a blue phosphor, a green phosphor, a yellow phosphor, and a red phosphor are mixed with a transparent resin so that the color temperature becomes the first temperature (the highest temperature). Prepare slurry mixed in proportion. This phosphor mixture slurry is applied to the surface of the substrate 11C corresponding to the first LED chip group 21. Thus, the first phosphor layer 12a (average thickness t1) for absorbing the primary light emitted from the first LED chip group 21 is formed.

Next, as the phosphor mixture, four phosphor materials of a blue phosphor, a green phosphor, a yellow phosphor, and a red phosphor are transparent resin so that the color temperature becomes the second temperature (intermediate temperature). And a slurry mixed at a predetermined ratio. This phosphor mixture slurry is applied to the surface of the substrate 11C corresponding to the second LED chip group 22. As a result, the second phosphor layer 12b (average thickness t1) for absorbing the primary light emitted from the second LED chip group 22 is formed.

Next, as a phosphor mixture, four phosphor materials of a blue phosphor, a green phosphor, a yellow phosphor, and a red phosphor are transparent resin so that the color temperature becomes the third temperature (the lowest temperature). And a slurry mixed at a predetermined ratio. This phosphor mixture slurry is applied to the surface of the substrate 11C corresponding to the third LED chip group 23. As a result, a third phosphor layer 12c (average thickness t1) for absorbing primary light emitted from the third LED chip group 23 is formed.

As shown in FIG. 10, these three

phosphor layers

12a, 12b, and 12c are surrounded by an annular partition 20a and two

linear partitions

20b and 20c, and are partitioned from other phosphor layers. Yes. The

barrier ribs

20a, 20b, and 20c shield light provided between the

adjacent phosphor layers

12a, 12b, and 12c in order to reduce absorption of primary light between the three LED light

source barrier ribs

13a, 13b, and 13c. It is a thing.

Partition walls

20a, 20b, and 20c are provided between the

adjacent phosphor layers

12a, 12b, and 12c, and the

phosphor layers

12a, 12b, and 12c are separated from each other by the

partition walls

20a, 20b, and 20c.

The

partition walls

20a, 20b, and 20c preferably include high-reflectivity inorganic fine particles that can reflect light having a wavelength of 450 to 780 nm up to 98%. It is preferable to form a partition wall by a slurry coating method using such highly reflective inorganic fine particles and a resin material. As the resin material, for example, one or a mixture of two or more selected from the group consisting of acrylic, silicone, phenol, urea, melamine, epoxy, polyurethane, polyolefin, and polyimide can be used. As the inorganic fine particles, one or more selected from the group consisting of titanium oxide, boron nitride, barium sulfate, alumina, and zinc oxide can be used. In particular, white pigments such as titania are preferable as the inorganic fine particles.

In the slurry application method, a white pigment and a resin solution are mixed and stirred at a predetermined ratio to produce a slurry, and this slurry is applied in a linear or strip form on the substrate 11C by a slurry application device. The

partition walls

20a, 20b, and 20c thus formed have a high reflectance with a light reflectance of up to 98%.

Next, the phosphor mixture and the resin solution are mixed and stirred at a predetermined ratio to produce a slurry, and this slurry is applied to a predetermined area on the substrate 11C by a slurry application device. The phosphor layers 12a, 12b, and 12c thus formed by coating have different color temperatures.

A virtual area surrounded by a two-dot chain line in FIG. 11 schematically shows a projection image 30 of the light scattering member when the axially symmetric light scattering member 15 is projected in parallel on the light emitting surface 18 of a plurality of light sources included on the same plane. It is shown in. The projected image 30 does not cover the entire coating area of the

phosphor layers

12a, 12b, and 12c, but overlaps each light emitting surface area of the plurality of light sources. Here, the light emitting surface area of the light source refers to a region occupied by the LED chip of the light emitting circuit in the XY plane. Specifically, all the first LED chip 24 groups overlap the projected image 30 in the center of the figure. Further, on the right side of the figure, the second LED chip 25 group all overlaps the projected image 30. In addition, all the third LED chips 26 overlap the projected image 30 on the left side of the figure.

As shown in FIGS. 12A to 12F, the embodiment of the multiple combination light source can be variously changed.

In the LED module 10A shown in FIG. 12A, the phosphor layers 12a and 12c of the two

LED light sources

13a and 13c are partitioned by an annular partition wall 20a and a linear partition wall 20b. One phosphor layer 12a contains a phosphor mixture having a first color temperature. The other phosphor layer 12c contains a phosphor mixture having the second color temperature.

In the LED module 10B shown in FIG. 12B, the

phosphor layers

12a, 12b, and 12c of the three

LED light sources

13a, 13b, and 13c are partitioned by the annular partition wall 20a and the three-

pronged partition walls

20b, 20c, and 20d. The first phosphor layer 12a contains a phosphor mixture having a first color temperature. The second phosphor layer 12b contains a phosphor mixture having the second color temperature. The third phosphor layer 12c contains a phosphor material having a third color temperature.

In the LED module 10C shown in FIG. 12C, the phosphor layers 12a and 12c of the two

LED light sources

13a and 13c are partitioned by

concentric partition walls

20a and 20e. The inner circular phosphor layer 12a contains a phosphor mixture having the first color temperature. The outer circular phosphor layer 12c contains the phosphor mixture having the third color temperature.

In the LED module 10D shown in FIG. 12D, the

phosphor layers

12a, 12b, 12c of the three

LED light sources

13a, 13b, 13c are partitioned by

concentric partition walls

20a, 20e and

linear partition walls

20b, 20c. The inner circular phosphor layer 12a contains a phosphor mixture having the first color temperature. One outer semicircular phosphor layer 12b contains a phosphor mixture having the second color temperature. The other outer semicircular phosphor layer 12c contains a phosphor mixture having a third color temperature.

In the LED module 10E shown in FIG. 12E,

phosphor layers

12a, 12b, 12c and 12d of four

LED light sources

13a, 13b, 13c and 13d are formed by

concentric partition walls

20a and 20e and

linear partition walls

20b, 20c and 20d. It is partitioned. The first phosphor layer 12a contains a phosphor mixture having a first color temperature. The second phosphor layer 12b contains a phosphor mixture having the second color temperature. The third phosphor layer 12c contains a phosphor mixture having a third color temperature. The fourth phosphor layer 12d contains a phosphor mixture having a fourth color temperature.

In the LED module 10F shown in FIG. 12F, three types of

phosphor layers

12a, 12b, and 12c are formed for five

LED light sources

13a, 13b, 13c, 13b, and 13c by an annular partition 20a and four L-shaped partitions 20f. It is partitioned. In the LED module 10F, three types of

phosphor layers

12a, 12b, and 12c are separately applied to the five

LED light sources

13a, 13b, 13c, 13b, and 13c. That is, the phosphor layer 12b containing the same phosphor mixture is applied to the second and fourth light sources, respectively, and the phosphor layer 12c containing the same phosphor mixture is applied to the third and fifth light sources, respectively. Yes.

In this example, the phosphor layer 12a of the first light source contains a phosphor mixture of the first color temperature, and the phosphor layer 12b of the second and fourth light sources contains the phosphor of the second color temperature. Mixtures are respectively included, and the phosphor layers 12c of the third and fifth light sources respectively include phosphor mixtures having a third color temperature.

In the present embodiment, the case where three types of white light sources having different color temperatures are used in combination has been described. However, the present invention is not limited to this, and in addition to this, two or four types or More white light sources can be used in combination. In addition, the more white light sources to be combined, the more delicate white light is reproduced, so that a good effect can be expected. However, excessively increasing the number of types of white light source is not preferable because it complicates light adjustment and color adjustment. Therefore, it is preferable to combine two to four types of white light sources, and it is most preferable to combine three types of white light sources.

Next, the relationship between the height of the barrier ribs and the thickness of the phosphor layer will be described with reference to FIGS.

In the LED module of the present embodiment, it is preferable that the average height h1 of the partition walls be in the range of 0.5 to 2 times the average thickness t1 of the phosphor layer. This is because when the average height h1 of the partition wall is in such an appropriate range, the light emission efficiency of the primary light from the plurality of LED chip groups increases. If the average height h1 of the barrier ribs is 0.5 times or more of the average thickness t1 of the phosphor layer, it is adjacent due to the wettability of the phosphor mixture-containing slurry (mixture of phosphors of each color and transparent resin solution) with respect to the barrier ribs. Contact between the matching phosphors does not occur.

For example, in the partition 20L shown in FIG. 14, the average height h1 of the partition 20L is lower than the thickness t1 of each

phosphor layer

12a, 12b, but if the average thickness t1 is 0.5 times or more, the

phosphor layers

12a, 12b They do not touch each other. In this case, the phosphor slurry is raised in a convex shape. Incidentally, it is sufficient that the average height h1 of the partition walls is several tens of μm or more. However, if the average height h1 of the barrier ribs is less than 0.5 times the average thickness t1 of the phosphor layers, the adjacent phosphor layers may come into contact with each other.

On the other hand, if the average height h1 of the barrier ribs exceeds twice the average thickness t1 of the phosphor layer, the non-light emitting area becomes excessive and the total luminous flux is reduced, so that the illumination becomes dark. However, if the average height h1 of the barrier ribs is less than twice the average thickness t1 of the phosphor layer, the decrease in the luminous efficiency of the secondary light is substantially negligible. For example, in the partition wall 20H shown in FIG. 13, the average height h1 of the partition wall 20H is higher than the average thickness t1 of the phosphor layers 12a and 12b in each area, but if it is less than twice the average thickness t1, emission of secondary light The efficiency is not substantially reduced and the lighting does not go dark.

Here, the average thickness of the phosphor layer refers to the average thickness of the phosphor material after the phosphor mixture-containing slurry is applied and the volatile components of the slurry are volatilized and lost. In the LED light source, the average thickness t1 of the phosphor layer is generally in the range of 400 to 2000 μm (0.4 to 2.0 mm).

The light emitting circuit of the LED module of this embodiment will be described with reference to FIG.

The LED module of this embodiment includes three

light sources

13a, 13b, and 13c. These three

light sources

13a, 13b, and 13c are respectively provided with

LED chip groups

21, 22, and 23 that include a plurality of

LED chips

24, 25, and 26.

The light emitting circuit of the first light source 13a is configured by connecting four LED chips 24 in series in the forward direction to form a series connection circuit, and connecting the four series connection circuits in parallel. The light emitting circuit of the first light source 13a has an LED chip group 21 including a total of 16 LED chips 24.

The light emitting circuit of the second light source 13b is configured by connecting three LED chips 25 in series in the forward direction to form a series connection circuit, and connecting the two series connection circuits in parallel. The light emitting circuit of the second light source 13b has an LED chip group 22 including a total of six LED chips 25. Further, a resistor R1 is inserted on the negative electrode side of the light emitting circuit of the second light source 13b. The resistor R1 is connected in series to the two parallel LED chip groups 22.

The light emitting circuit of the third light source 13c is configured by connecting two LED chips 26 in series in the forward direction to form a series connection circuit, and connecting the two series connection circuits in parallel. The LED chip group 23 of the third light source has an LED chip group 23 including a total of four LED chips 26. Further, a resistor R2 is inserted on the negative electrode side of the light emitting circuit of the third light source 13c. The resistor R2 is connected in series to the two parallel LED chip groups 23.

Note that each of the insertion resistors R1 and R2 is a variable resistance element in order to investigate a change in the light emission characteristics due to a change in the resistance value of the light emitting circuit.

Even when the series number of the first to third

LED chip groups

21, 22, 23 is changed, the slope of the current-voltage characteristic line is partially changed by changing the insertion resistances R1, R2, respectively. As a whole, the emission characteristics can be adjusted to a desired one. Specifically, the position CP2 of the intersection of the current-voltage characteristic line A of the light emitting circuit of the first light source and the current-voltage characteristic line B of the light emitting circuit of the second light source is adjusted by changing the value of the insertion resistor R1. Further, by changing the value of the insertion resistance R2, the current-voltage characteristic line A of the light emitting circuit of the first light source and the current-voltage characteristic line C of the light emitting circuit of the third light source are changed as shown in FIG. The position of the intersection CP1 can be adjusted. Thereby, the light emission characteristic line E of the white LED illumination device can be approximated to the light emission characteristic line F of the incandescent lamp as shown in FIG.

In this embodiment, the insertion resistors R1 and R2 are mounted on the circuit board 11C as the LED package by chip-on-board technology, but these insertion resistors R1 and R2 are mounted on other members other than the circuit board 11C. You may make it mount.

Further, a power supply circuit for supplying power to the light emitting circuits of the three

light sources

13a, 13b, and 13c will be described with reference to FIG.

The light emitting circuits of the first to third

light sources

13a, 13b, and 13c are connected together at the positive electrode side to the common electrode 27d. The positive common electrode 27d is connected to the positive terminal 42a of the lighting circuit 42.

On the other hand, in the light emitting circuit of the first light source 13a, the negative electrode side is connected to the individual electrode 27a. The light emitting circuit of the second light source 13b is connected to the individual electrode 27b on the negative electrode side. The light emitting circuit of the third light source 13c is connected to the individual electrode 27c on the negative electrode side. These

negative electrodes

27a, 27b, and 27c are connected to the negative terminal 42b of the lighting circuit 42, respectively.

The operation of the lighting device of this embodiment will be described.

When the bulb-type lighting device 1 is attached to a commercial AC power socket serving as the external power source 40, a current flows from the external power source 40 (commercial AC power source) to the lighting circuit 42 in the lighting device, and the lighting circuit 42 is activated. Electric power is supplied to the light emitting circuits of the three

light sources

13a, 13b, and 13c, and the

LED chip groups

21, 22, and 23 of each light source emit light.

White light emitted from each of the three

light sources

13a, 13b, and 13c has different emission spectra (that is, different color temperatures). These three types of white light having different color temperatures are guided by the transparent member 14 to the lens-shaped thickness changing portion 16 and collected by the thickness changing portion 16 toward the light scattering member 15. In this way, the light 8 traveling from the light scattering member 15 toward the distal end is collected by the light scattering member 15.

On the other hand, the light directed toward the side and the base end is guided toward the bottom surface 15e of the light scattering member by the thickness changing portion 16 of the transparent member 14 while being reflected by the transparent member 14. Thus, as a result of the light 8 concentrating toward the bottom surface 15e of the light scattering member of the transparent member, it looks from the outside as if light is emitted from the bottom surface 15e of the light scattering member. Thereby, the lighting method of the illumination device of the present embodiment is close to that of the incandescent bulb.

Further, the operation and effect of the present embodiment will be described with reference to the characteristic diagrams shown in FIGS.

FIG. 16 is a characteristic diagram showing current-voltage characteristics for a single white LED light source and a three-type combined white LED light source, respectively.

In the figure, the characteristic line A is the current-voltage characteristic of the light emitting circuit (no insertion resistor) of the first light source 13a, and the characteristic line B is the variable resistor R1 inserted in the light emitting circuit of the second light source 13b is set to 50Ω. The characteristic line C shows the current-voltage characteristic when the variable resistor R2 inserted in the light emitting circuit of the third light source 13c is set to 300Ω.

Characteristic line D shows the current-voltage characteristics of the light emitting circuit of the three-type combination light source. The characteristic line D has two inflection points IP1 and IP2. The first inflection point IP1 corresponds to the intersection point CP1 between the characteristic line A and the characteristic line C, and the second inflection point IP2 corresponds to the intersection point CP2 between the characteristic line A and the characteristic line B.

In the characteristic line D, the slope of the current-voltage characteristic line is the largest up to the first inflection point IP1 (about 20 mA). This indicates that a current is actively flowing through the first light source 13a.

As the current is increased in the characteristic line D, the slope of the current-voltage characteristic line changes from the slope of the characteristic line C to the slope of the characteristic line B at the first inflection point IP1. This is because when the input current exceeds the first inflection point IP1, the current flowing through the third light source 13c becomes saturated, and the current flows positively with priority given to the second light source 13b. Show.

In the characteristic line D, the current exceeds the first inflection point IP1 (about 20 mA), and the slope of the current-voltage characteristic line reaches the first inflection point IP1 until the second inflection point IP2 (about 60 mA). The voltage of the second light source 13b is equal to the voltage of the third light source 13c. This indicates that the current flowing through the third light source 13c becomes saturated, and the current flows positively with priority given to the second light source 13b.

In this embodiment, as shown in FIG. 15, resistors R1 and R2 are inserted on the negative electrode side in the light emitting circuits of the

light sources

13b and 13c having a low color temperature. These insertion resistors R1 and R2 cause an inflection point in the current-voltage characteristic line of the light emitting circuit of the light source 13a having a high color temperature, and if the input current is lowered to a point lower than the inflection point of the characteristic line, Will actively flow toward the light emitting circuit of the light source with a low color temperature. Thereby, as the total luminous flux decreases, the shade of white light becomes reddish, and white illumination light close to natural light can be obtained.

FIG. 17 is a characteristic diagram showing the relationship between total luminous flux and input current in the three-type combination white LED lighting device.

From the characteristic line H, it can be seen that the input current and the total luminous flux are almost in direct proportion, and that the total luminous flux increases as the input current increases. That is, if the illumination is to be brightened, the amount of current supplied may be increased.

FIG. 18 is a characteristic diagram showing the relationship between the color temperature and the total luminous flux by comparing the three kinds of combination white LED lighting devices and incandescent bulbs.

In the figure, characteristic line E indicates the light emission characteristics of the three-type combined white LED lighting device (example), and characteristic line F indicates the light emission characteristics of the incandescent bulb (comparative example). From both characteristic lines E and F, it was recognized that the light emission characteristics of the white LED lighting device of this embodiment approximate the light emission characteristics of the incandescent bulb in a wide range from about 2000K to about 2800K.

Further, from the characteristic line E, the color temperature changes with respect to the total luminous flux. The higher the total luminous flux, the closer to the color temperature 2800K of the light from the first light source 13a, and the lower the total luminous flux, the second light source 13b. It was observed that the color temperature of the light from 2400K and the color temperature of the light from the third light source 13c approached 2000K.

(Second Embodiment)
A multiple combination LED light source used in the LED module according to the second embodiment will be described with reference to FIGS. 19 to 24 and FIG. 12A, respectively. Note that description of portions in which this embodiment overlaps with the above embodiment is omitted.

The LED module 10A of the second embodiment includes two types of combined

white light sources

13a and 13c including

phosphor layers

12a and 12c partitioned as shown in FIG. 12A. The two-type combined

white light sources

13a and 13c have a light emitting circuit shown in FIG.

FIG. 19 shows a light-emitting circuit when resistors having various resistance values are inserted into a single white light source. The light emitting circuit of FIG. 19 is shown as a comparative example to the light emitting circuit of the second embodiment shown in FIG.

FIG. 20 shows current-voltage characteristics of the light emitting circuits of the various single white light sources shown in FIG. The current-voltage characteristics in FIG. 20 are shown as a comparative example for the current-voltage characteristics of the light emitting circuit of the second embodiment shown in FIG.

21. The two combination

white light sources

13a and 13c shown in FIG. 21 have the following configuration.

The light-emitting circuit of the first light source 13a is formed by connecting four LED chips 24 in series in the forward direction to form a series circuit, and connecting the four series circuits in parallel. Have. The LED chip group 21 of the first light source includes a total of 16 LED chips 24.

The light-emitting circuit of the second light source 13c includes two LED chips 26 connected in series in the forward direction to form a series circuit, and two LED chips 23 formed by connecting the two series circuits in parallel. Have. The LED chip group 23 of the second light source includes a total of four LED chips 26. Further, a variable resistor R2 is inserted on the negative electrode side of the light emitting circuit of the second light source 13c. The resistor R2 is connected to the LED chip group 23 in series.

Even when the series number of the first and second

LED chip groups

21 and 23 is changed, the position of the intersection of both current-voltage characteristic lines can be adjusted by changing the value of the insertion resistance R2. Therefore, the light emission characteristic line of the white LED lighting device can be brought close to the light emission characteristic line of the incandescent bulb.

Also, the insertion resistor R2 is a variable resistance element in order to investigate the change in the light emission characteristics due to the change in the resistance value. Further, in this embodiment, the insertion resistor R2 is mounted on the circuit board 11C (LED package) by chip-on-board technology, but the resistor R2 is mounted on a member other than the circuit board 11C. Also good.

FIG. 20 is a characteristic diagram showing current-voltage characteristics of various white LED light sources having a single color temperature.

The characteristic line A in the figure shows the current-voltage characteristic of the light emitting circuit of the first light source 13a.

The characteristic line B1 shows the current-voltage characteristic of the light emitting circuit with a resistance of 100Ω inserted on the negative side of the second light source 13c, and the characteristic line B2 shows the current of the light emitting circuit with a resistance of 300Ω on the negative side of the second light source 13c− The voltage characteristic, the characteristic line B3 is the current-voltage characteristic of the light emitting circuit in which the resistor 500Ω is inserted on the negative electrode side of the second light source 13c, and the characteristic line B0 has no insertion resistance of the second light source 13c (resistance 0Ω). The current-voltage characteristics of the light emitting circuit are shown respectively.

The characteristic line B0 generates a lower voltage than the characteristic line A of the first light source 13a for the same current, and is almost parallel to the characteristic line A. However, as the value of the insertion resistance R2 increases, the generated voltage of the light emitting circuit 23R increases, and the slope gradually increases as shown by the characteristic lines B1, B2, B3. Therefore, as shown in FIG. B2 and B3 and characteristic line A have intersections P, Q and R, respectively. The intersections P, Q, and R of two current-voltage characteristic lines having different slopes cause new inflection points in the current-voltage characteristic lines having the smaller slopes.

Fig. 22 shows the current-voltage characteristics of a two-type combination white LED lighting device in which two different color temperatures are combined.

In the figure, the characteristic line A shows the current-voltage characteristic of the light emitting circuit of the first light source 13a, and the characteristic line B2 shows the current-voltage characteristic of the light emitting circuit in which a resistor 300Ω is inserted on the negative electrode side of the second light source 13c. Show. A characteristic line G indicates current-voltage characteristics of the light emitting circuits of the two kinds of combined

light sources

13a and 13c.

In this combination

light source

13a, 13c, a current flows positively through the second light source 13c up to a current of 20 mA. However, when the current exceeds 20 mA, the light emission circuit of the first light source 13a and the light emission circuit of the second light source 13c become equipotential. This is because, in the current-voltage characteristics of this light emitting circuit, there is an inflection point IP3 where the slope of the characteristic line changes suddenly at 20 mA. The inflection point IP3 is determined based on the intersection point CP3 between the characteristic line A and the characteristic line B2.

FIG. 23 shows the relationship between the current (partial current) flowing in each area and the input current (total current) in the two-type combination white LED light source.

The characteristic line J in the figure shows the current-voltage characteristic of the light emitting circuit of the first light source 13a, and the characteristic line K shows the current-voltage characteristic of the light emitting circuit of the second light source 13c.

From both the characteristic lines J and K, when the input current is less than 20 mA, the current actively flows through the light emitting circuit of the second light source 13c. However, when the input current exceeds 20 mA, the current value of the light source circuit of the second light source 13c is saturated. Then, it can be seen that a current actively flows through the light emitting circuit of the first light source 13a.

From the characteristic line L in FIG. 24, it can be seen that the input current and the total luminous flux are almost directly proportional, and the total luminous flux increases as the input current increases.

FIG. 25 shows the relationship between the color temperature and the total luminous flux by comparing two types of combined white LED lighting devices and incandescent bulbs.

The characteristic line M in the figure indicates the light emission characteristic of the two-type combined white LED lighting device, and the characteristic line F indicates the light emission characteristic of the incandescent bulb. From both characteristic lines M and F, it was confirmed that the light emission characteristics of the white LED lighting device of the present embodiment approximate the light emission characteristics of the incandescent bulb in a wide range from about 2000K to about 2800K. Further, from the characteristic line M, the color temperature changes with respect to the total luminous flux. The higher the total luminous flux, the closer to the color temperature 2800K of the light from the first light source 13a, and the lower the total luminous flux, the second light source 13b. It was observed that the color temperature of the light from was approaching 2000K.

Below, the light emission characteristics of the LED bulb of the example incorporating the actually produced LED module will be described in comparison with that of the LED bulb of the comparative example.

(Example 1)
As Example 1, the LED module 10 having the three types of white LED light sources shown in FIG. 10 was produced, and this was incorporated into a globe to produce the LED bulb shown in FIG.

(Production of partition walls)
Titania fine particles as a white pigment were mixed and stirred in a silicone resin solution at a predetermined ratio, and the obtained slurry was applied linearly to a predetermined area of the LED circuit board by a coating device to form a partition. The partition walls formed had an average height of 0.5 mm and an average width of 1.2 mm.

(Preparation of phosphor layer)
A phosphor mixture slurry having a color temperature of 2840K was applied to the first light emitting area of the substrate to form a phosphor layer for the first light source. The phosphor mixture slurry is obtained by mixing four types of blue phosphor, green phosphor, yellow phosphor, and red phosphor having the following composition with a transparent resin at a predetermined ratio. The formed first phosphor layer had an average thickness of 0.5 mm.

Blue phosphor; (Sr _0.81 Ba _0.12 Ca _0.01 Eu _0.06 ) ₅ (PO ₄ ) ₃ Cl
Green phosphor; (Sr _0.235 Ba _0.5 Mg _0.05 Eu _0.2 Mn _0.015 ) ₂ SiO ₄
Yellow phosphor; (Sr _0.5292 Ba _0.25 Mg _0.07 Eu _0.15 Mn _0.0008 ) ₂ SiO ₄
Red phosphor; (Sr _0.8 Eu _0.2 ) ₃ Si ₇ Al ₂ O _1.5 N ₈
A phosphor mixture slurry having a color temperature of 2582K was applied to the second light emitting area of the substrate to form a phosphor layer for the second light source. The phosphor mixture slurry is obtained by mixing four types of blue phosphor, green phosphor, yellow phosphor, and red phosphor having the following composition with a transparent resin at a predetermined ratio. The formed second phosphor layer had an average thickness of 0.5 mm.

Blue phosphor; (Sr _0.78 Ba _0.15 Ca _0.02 Eu _0.05 ) ₅ (PO ₄ ) ₃ Cl
Green phosphor; (Sr _0.9 Eu _0.1 ) ₃ Si ₁₀ Al ₃ O ₂ N ₂ 0
Yellow phosphor; (Sr _0.6493 Ba _0.2 Mg _0.05 Eu _0.1 Mn _0.0007 ) ₂ SiO ₄
Red phosphor; (Sr _0.85 Eu _0.15 ) _2.5 Si ₆ Al ₄ O _0.5 N ₁₀
A phosphor mixture slurry having a color temperature of 2032K was applied to the third light emitting area of the substrate to form a phosphor layer for the third light source. The phosphor mixture slurry is obtained by mixing four types of blue phosphor, green phosphor, yellow phosphor, and red phosphor having the following composition with a transparent resin at a predetermined ratio. The formed third phosphor layer had an average thickness of 0.5 mm.

Blue phosphor; (Sr _0.72 Ba _0.2 Ca _0.01 Eu _0.07 ) ₅ (PO ₄ ) ₃ Cl
Green phosphor; (Sr _0.24 Ba _0.55 Mg _0.1 Eu _0.1 Mn _0.01 ) ₂ SiO ₄
Yellow phosphor; (Sr _0.769 Ba _0.15 Mg _0.03 Eu _0.05 Mn _0.001 ) ₂ SiO ₄
Red phosphor; (Sr _0.9 Eu _0.1 ) ₂ Si ₈ Al ₃ ON ₁₃
The size of each part of the LED module of FIG. 10 is shown below.

Width W2; 9.8mm
Width W3; 4.7mm
Width W4; 2.55mm
(LED chip)
Twenty-six blue LED chips were incorporated into the light emitting circuit of FIG. A COB drive voltage of 3.1 V was applied when a current of 300 mA was applied thereto, and primary light was emitted from each blue LED chip at an emission wavelength of 400 to 410 nm.

(Production of axisymmetric transparent member)
A transparent acrylic resin was injection molded by an injection molding machine to form a cylindrical axisymmetric transparent member having a tapered thickness change portion and a hollow portion. The axially symmetric transparent member had an overall length L ₀ of 25.4 mm, a thickness changing portion (hollow portion) length L ₁ of 10.2 mm, a distance L ₂ of 14.8 mm, and a maximum diameter d ₀ of 10.2 mm.

(Production of axisymmetric light scattering member)
A titania pigment as light scattering particles is mixed and stirred in a transparent nitrocellulose solution at a predetermined ratio, and the obtained slurry is thinly applied to the peripheral wall surface of the hollow portion of the axially symmetric transparent member by an application device. Formed. The average thickness of the coating layer constituting the axially symmetric light scattering member was set in the range of 50 to 100 μm.

(Example 2)
As Example 2, an LED module 10A having two types of white LED light sources shown in FIG. 12A was produced, and this was incorporated into a globe to produce the LED bulb shown in FIG.

(Production of partition walls)
Sekisui Plastics Co., Ltd. Techpolymer (registered trademark) as white particles is mixed and stirred in a silicone resin solution at a predetermined ratio, and the resulting slurry is applied linearly to a predetermined area of the LED circuit board with a coating device. A partition wall was formed. Techpolymer is a light scattering fine particle in which a pigment is incorporated into a transparent resin. In addition to light scattering, it is a fine particle that can suppress light in the blue light region (380 to 500 nm wavelength range) that is abundant in LED light. is there.

The formed partition walls had an average height of 0.5 mm and an average width of 1.2 mm.

(Preparation of phosphor layer)
A phosphor mixture slurry having the same composition as in Example 1 and having a color temperature of 2840K was applied to the first light emitting area of the substrate to form a phosphor layer for the first light source. The formed first phosphor layer had an average thickness of 0.4 mm.

A phosphor mixture slurry having the same composition as in Example 1 and having a color temperature of 2032K was applied to the second light emitting area of the substrate to form a phosphor layer for the second light source. The formed second phosphor layer had an average thickness of 0.4 mm.

(LED chip)
Twenty blue LED chips were incorporated into the light emitting circuit of FIG. A COB drive voltage of 3.1 V was applied when a current of 300 mA was applied thereto, and primary light was emitted from each blue LED chip at an emission wavelength of 400 to 410 nm.

The same axisymmetric transparent member and axisymmetric light scattering member as in Example 2 were used.

(Comparative Example 1)
As Comparative Example 1, a white LED lighting device having a plurality of LED light sources having the same configuration as that of Example 1 was prepared except that there was no axially symmetric transparent member and no axially symmetric light scattering member.

(Comparative Example 2)
As Comparative Example 2, a white LED lighting device having a plurality of LED light sources having the same configuration as that of Example 2 was prepared except that there was no axially symmetric transparent member and no axially symmetric light scattering member.

(Evaluation test results)
In order to quantify the color variation when the light source of each lighting device was viewed during lighting, the color temperature variation of each device was measured with a color luminance meter, and the obtained measured value was evaluated. A product model number CS-100A manufactured by Konica Minolta Co., Ltd. was used as a color luminance meter. The variation in color temperature is obtained by measuring six different locations on the light emitting surface of the light source. The results are shown in Table 1.

In Example 1, since the light scattering member emits light by mixing three types of light having different color temperatures in the lens-shaped thickness change portion of the transparent member, the entire light bulb appeared to be evenly bright and uniform.

On the other hand, in Comparative Example 1, since the difference in color temperature of the phosphor layer that emitted light looks as it is, the top of the bulb is bright, the other parts are dark, and the color unevenness appears to be large.

Further, in Example 2, since the light scattering member emits light by mixing two kinds of light having different color temperatures in the lens-shaped thickness change portion of the transparent member, the entire light bulb looks evenly bright and has no color unevenness. It was.

On the other hand, in Comparative Example 2, since the difference in color temperature of the phosphor layer that emitted light looks as it is, the top of the bulb is bright, the other parts are dark, and the color unevenness appears large.

1 ... Lighting device, 2 ... Glove, 3 ... Base, 4 ... Heat dissipation housing (heat sink), 5 ... Screw,
6 ... Lens presser, 8 ... Luminescent light, 9 ... scattered light,
10 ... LED module, 11 ... substrate, 11B ... common circuit board, 11C ... LED chip group circuit board,
12,12a, 12b, 12c ... phosphor layer,
13 ... LED light source, 14 ... axisymmetric transparent member, 14h ... hollow part, 15 ... axisymmetric light scattering member, 15e ... bottom surface,
16 ... thickness change part, 17 ... light scattering particles (white particles),
18 ... light emitting surface, 18a, 18b, 18c ... light emitting area,
20, 20a, 20b, 20c, 20d, 20e, 20f ... partition wall, 21, 22, 23 ... LED chip group, 24, 25, 26 ... LED chip, 27a, 27b, 27c, 27d ... electrode,
30 ... projected image, 40 ... external power supply, 42 ... lighting circuit (built-in converter), 42a, 42b ... terminals.

Claims

A plurality of LED light sources each having a light emitting surface included in the same plane, each emitting light from the light emitting surface with a different emission spectrum in the visible light region;
Axisymmetric transparent member formed symmetrically about a light distribution symmetry axis substantially orthogonal to the plane, covering the light emitting surface of the plurality of LED light sources, and guiding light emitted from the plurality of LED light sources When,
Axis formed symmetrically around the light distribution symmetry axis, located away from the plurality of LED light sources, provided inside the axis symmetry transparent member, and an axis for scattering light guided by the axis symmetry transparent member A symmetric light scattering member;
Comprising
The LED module, wherein a projected image of the axisymmetric light scattering member projected in parallel on the plane overlaps at least a part of each light emitting surface of the plurality of LED light sources.
The axisymmetric transparent member has a side surface that substantially totally reflects light emitted from the plurality of LED light sources, and a thickness change portion in which the thickness gradually decreases from the base end side toward the tip end side. And
The thickness change portion is
An outer diameter reduced portion whose outer diameter gradually decreases from the proximal end side toward the distal end side, and the inside of the axisymmetric transparent member corresponding to the outer diameter reduced portion, and from the proximal end side toward the distal end side A hollow portion whose inner diameter gradually increases,
The LED module according to claim 1, wherein the light reflected from the side surface by the thickness changing portion is collected in a predetermined region in the hollow portion.
3. The LED module according to claim 2, wherein the axisymmetric light scattering member is a layer covering a peripheral wall of the hollow portion.
The LED light source has a substantially symmetrical light distribution around the light distribution axis;
The light emitting surfaces of the plurality of LED light sources have an area C,
The axially symmetric transparent member has a first symmetry axis that substantially coincides with the light distribution symmetry axis of the LED light source, and is axially symmetric about the first symmetry axis;
The axially symmetric light scattering member has a second symmetry axis that substantially coincides with the orientation symmetry axis of the LED light source, is axially symmetric about the second symmetry axis, and has a bottom surface with a diameter d 1 . And having a length L 1 along the second axis of symmetry, the bottom surface being located at a closest distance L 2 from the light emitting surface of the plurality of LED light sources, and the closest distance L 2 And the area C satisfies the relationship of the following formula (1),

The length L 1 of the axisymmetric light scattering member and the absorption coefficient μ (1 / mm) of the axisymmetric light scattering member 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 maximum cross section of the axisymmetric light scattering member orthogonal to the second symmetry axis is included in a minimum cross section of the axisymmetric transparent member orthogonal to the first symmetry axis;
When the axially symmetric transparent member is projected in parallel on the plurality of types of light emitting surfaces, the projected image overlaps the light emitting surfaces of the plurality of LED light sources so as to include the light emitting surfaces of the plurality of LED light sources. The LED module according to claim 1.
5. The LED module according to claim 4, wherein the axially symmetric transparent member is formed in a cylindrical shape at a portion close to the LED light source, and is formed in a truncated cone shape at a portion far from the LED light source. .
6. The LED module according to claim 5, wherein the axially symmetric transparent member and the axially symmetric light scattering member satisfy the relationship of the following formula (4).

Where d 0 is the diameter of the axisymmetric transparent member.
The plurality of LED light sources includes a plurality of LED chips that emit primary light in the ultraviolet or visible region, and a plurality of phosphor layers that absorb the primary light and emit secondary light in the visible region. The LED module according to claim 1.
The plurality of LED light sources include a plurality of LED chip groups each emitting visible light having a different emission spectrum in the visible light region as the primary light, and the white light having a different color temperature as the secondary light by absorbing the primary light. The LED module according to claim 7, further comprising a plurality of phosphor layers that respectively emit light.
The plurality of LED light sources are provided adjacent to a circuit board including the plurality of LED chip groups and the plurality of phosphor layers, and around the phosphor layer so as to surround the phosphor layer in the plane. Barrier ribs that bring the phosphor layers into non-contact with each other;
The LED module according to claim 8, further comprising:
10. The LED module according to claim 9, wherein the average height of the partition walls is in the range of 0.5 to 2 times the average thickness of the phosphor layer.
The partition wall is dispersed in the resin material and one or more resin materials selected from the group consisting of acrylic, silicone, phenol, urea, melamine, epoxy, polyurethane, polyolefin, and polyimide, and titanium oxide. The LED module according to claim 9, further comprising one or more inorganic fine particles selected from the group consisting of boron nitride, barium sulfate, alumina, and zinc oxide.
A glove enclosing the LED module;
A heat dissipating case connected to the globe and thermally connected to the LED module;
A lighting circuit that is included in the heat dissipation casing, converts alternating current into direct current, and supplies direct current to the LED module;
A base connected to the heat dissipation housing and supplied with electric power from an external power source via the lighting circuit;
Comprising
The LED module
A plurality of LED light sources including a plurality of LED chips that are lit by the lighting circuit, each having a light emitting surface included in the same plane, and each emitting light having a different emission spectrum in the visible light region from the light emitting surface; ,
Axisymmetric transparent member formed symmetrically about a light distribution symmetry axis substantially orthogonal to the plane, covering the light emitting surface of the plurality of LED light sources, and guiding light emitted from the plurality of LED light sources When,
Axis formed symmetrically around the light distribution symmetry axis, located away from the plurality of LED light sources, provided inside the axis symmetry transparent member, and an axis for scattering light guided by the axis symmetry transparent member A symmetric light scattering member;
Comprising
An illumination device, wherein a projected image of the axisymmetric light scattering member projected in parallel on the plane overlaps at least a part of each light emitting surface of the plurality of LED light sources.