JP2007081090A - White light emitter and lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a white light emitter capable of reducing color variation in a high color rendering white light emitter combining a light emitting element and a plurality of kinds of phosphors, and an illumination device using the white light emitter.
Dispersed are a base material having a cup-shaped recess, a blue light emitting diode mounted on the bottom surface of the recess, and a phosphor that fills the recess and is excited by blue light to emit visible light other than blue. A white light-emitting body having a transparent resin portion, wherein at least two kinds of the phosphors are used, and the transparent resin portion includes at least two layers having different phosphors, The type of the phosphor contained in the lower layer provided on the bottom side of the recess among the layers is the same as or less than the type of the phosphor contained in the upper layer provided on the opening side of the recess. A white light emitter characterized by the above.
[Selection] Figure 1

Description

  The present invention relates to a white light-emitting body configured to emit white light by combining a blue light-emitting diode (hereinafter referred to as blue LED) and a phosphor, and an illumination device using the white light-emitting body.

  More than 10 years have passed since the development of GaN-based LEDs as blue LEDs, and the LED application fields are rapidly expanding as the efficiency of LEDs themselves increases and the price decreases. In particular, coupled with the realization of white LEDs by the combination of blue LEDs and phosphors, LEDs have come to be used as light sources in the illumination field.

  FIG. 2 is a cross-sectional view illustrating the structure of a white light emitter by a combination of a conventional blue LED and a phosphor. This conventional white light-emitting body 1 includes a base material 2 having a cup-shaped concave portion 3, a blue LED element 4 mounted on the bottom surface of the concave portion 3 of the base material 2, and a phosphor 5 filled in the concave portion 3. The transparent resin portion 6 is made to be formed. The transparent resin portion 6 is made of a transparent resin, such as a transparent epoxy resin, in which fine phosphors 5 that are excited by blue light and emit visible light other than blue light, such as yellow light, are dispersed. The blue LED element 4 is sealed inside. In this white light emitter 1, by turning on the blue LED element 4, a part of the blue light is absorbed by the phosphor 5, and the phosphor 5 is excited to emit visible region fluorescence such as yellow light. Mixed color light (white light) of light and fluorescence is emitted from the opening of the recess 3. Although not shown, in order to function as the white light emitter 1, in addition to this, means for energizing the blue LED 4 is necessary. In some cases, the lens, the diffusion plate, and the base material for controlling the light are protected. A member for is added.

Further, in the case of lighting applications, as described in Patent Document 1, an LED capable of high color rendering white light emission has been proposed. The LED described in Patent Document 1 is a combination of a blue LED, a first fluorescent material that emits yellow light by blue light, and a second fluorescent material that emits red light by blue light. Color rendering white light emission is possible.
JP 2003-101081 A

However, as described in Patent Document 1, in order to obtain white light with high color rendering properties, when a white light emitter is configured by combining at least two kinds of phosphors and a blue LED, individual white light emission There was a problem that the color variation of the body became large.
The inventors have investigated the cause, and at the point of filling the concave portion of the base material with a material in which a plurality of types of phosphors are mixed and dispersed in a transparent resin, the concentration variation of each phosphor is reduced and filled. However, since the dispersion state of each phosphor cannot be equal, the dispersion state of a plurality of kinds of phosphors varies to some extent, and the light emission colors of the manufactured white light emitters are compared. In this case, it was found that color variation occurred.

As a specific example, a case where two types of phosphors are used will be described with reference to FIG. White light emitters 7A, 7B, and 7C shown in FIGS. 3A to 3C include a base material 2 having a cup-shaped concave portion 3, and a blue LED element 4 mounted on the bottom surface of the concave portion 3 of the base material 2. The first and second phosphors 8 and 9 are filled in the recess 3 and the transparent resin portion 6 is dispersed.
As shown in FIG. 3 (a), when the transparent material is filled with the first phosphor 8 and the second phosphor 9 in a dispersed state and cured, the transparent resin is shown in FIGS. 3 (b) and 3 (c). As shown, the distribution of the individual phosphors varies, and as a result, the emission colors of the produced white light emitters 7B and 7C vary. In the white light-emitting body 7B of (b), there are many first phosphors 8 on the upper side, and many second phosphors 9 are distributed on the blue LED element 4 side. On the other hand, in the white light emitter 7C of (c), the first phosphor 8 is distributed more on the blue LED element 4 side, and the second phosphor 9 is distributed more on the upper side. In this way, when the white phosphors 7B and 7C of (b) and (c) having different distributions of the individual phosphors are produced, when the emission colors of the produced individual white phosphors are compared, Variation will occur.

  Such a color variation is particularly noticeable in a white light emitting body aiming at high color rendering by adding a red phosphor to a combination of a blue LED and a yellow phosphor currently in practical use. That is, since the current red phosphor has a wide absorption spectrum (excitation spectrum), it absorbs not only blue light emitted from the blue LED but also yellow emitted from the yellow phosphor. For this reason, for example, in the case where many red phosphors are distributed on the upper side and the case where many red phosphors are distributed on the lower side (blue LED side), the color of the mixed light emitted even if the phosphor concentration is the same Will be different.

  The present invention has been made in view of the above circumstances, and a white light-emitting body capable of reducing color variation in a high color rendering white light-emitting body in which a light-emitting element and a plurality of types of phosphors are combined, and an illumination device using the white light-emitting body For the purpose of provision.

  In order to achieve the above object, the present invention provides a base material having a cup-shaped recess, a blue LED mounted on the bottom surface of the recess, and a visible light other than blue that is filled in the recess and excited by blue light. A white light emitting body having a transparent resin portion in which a phosphor emitting phosphor is dispersed, wherein at least two kinds of the phosphor are used, and the transparent resin portion includes at least two layers having different phosphors. Of these layers, the phosphor type contained in the lower layer provided on the bottom surface side of the recess is the type of phosphor contained in the upper layer provided on the opening side of the recess. A white light emitter is provided which is characterized by being the same as or less than.

  In the white light-emitting body of the present invention, it is preferable that the phosphor contained in the lower layer has a wider excitation wavelength region than the phosphor contained only in the upper layer.

  In the white light-emitting body of the present invention, it is preferable that the excitation spectrum of the phosphor contained in the lower layer at least partially overlaps the emission spectrum of the phosphor contained only in the upper layer. .

  In the white light-emitting body of the present invention, it is preferable that the average color rendering index is higher than when a blue LED and two types of phosphors are used and only one of the phosphors is used.

  In the white light-emitting body of the present invention, it is preferable that one of the two types of phosphors is a yellow phosphor and the other is a red phosphor.

  In the white light-emitting body of the present invention, it is preferable that the average color rendering index is higher than when a blue LED and three kinds of phosphors are used and only one or two kinds of the phosphors are used.

  Moreover, this invention provides the illuminating device which has the white light-emitting body based on this invention mentioned above as a light source.

  The white light-emitting body of the present invention uses at least two kinds of phosphors, and the transparent resin layer includes at least two different phosphors, and the lower side provided on the bottom surface side of the concave portion among these layers. Since the type of phosphor contained in the layer is the same or less than the type of phosphor contained in the upper layer provided on the opening side of the recess, two or more types of phosphors are transparent together Compared with the case where the transparent resin portion is provided by being dispersed in the resin, the light emission colors of the individual white light emitters to be manufactured are equal, and the color variation can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing an embodiment of a white light emitter according to the present invention. The white light emitter 11 according to the present embodiment includes a base material 12 having a cup-shaped recess 13, a blue LED element 14 mounted on the bottom surface of the recess 13 of the base material 12, and a first phosphor 16. The transparent resin portion is divided into two layers, a lower layer 15 on the bottom surface side of the recess and an upper layer 17 on the recess opening side in which the second phosphor 18 is dispersed.

  The material of the substrate 12 is not particularly limited, and for example, an aluminum laminated substrate or a glass epoxy substrate can be used. In addition, the shape and size of the recess 13 provided in the base 12 is such that the blue light from the blue LED element 14 mounted on the bottom surface of the recess 13 and the fluorescence from each phosphor are mixed and emitted from the recess opening. There is no particular limitation as long as it is possible. Although not shown, the base material 12 is formed with a plurality of wirings extending into the recess 13 as means for energizing the blue LED element 14. Furthermore, a lens, a diffusion plate, a reinforcing member for protecting the substrate, and the like can be added to the substrate 12 as necessary.

  The blue LED element 14 is an LED element that emits blue light, for example, a GaN LED. When the blue LED element 14 is mounted on the bottom surface of the concave portion 13 of the base material 12, the blue LED element 14 is fixed on one wiring extending on the bottom surface by solder or conductive paste, so that the blue LED One electrode terminal of the element 14 and the one wiring are electrically connected, and the other electrode terminal of the blue LED element 14 and the other wiring are electrically connected by wire bonding using a gold thin wire or the like. .

  The transparent resin portion divided into two layers, the lower layer 15 and the upper layer 17, disperses the first phosphor 16 in the lower layer 15 and the second phosphor 18 in the upper layer 17 in a transparent resin such as a transparent epoxy resin, The concave portion 13 is laminated.

The first phosphor 16 included in the lower layer 15 is preferably a phosphor having an excitation spectrum overlapping with an emission spectrum of a phosphor having a relatively wide excitation spectrum or another phosphor.
On the other hand, the second phosphor 18 included in the upper layer 17 is a phosphor whose excitation spectrum is relatively narrow compared to the first phosphor 16 and whose excitation spectrum does not overlap the emission spectrum of the first phosphor 16. It is desirable to be.
For example, when using a red phosphor having a relatively wide excitation spectrum and a yellow phosphor having a relatively narrow excitation spectrum, the red phosphor is mixed as the first phosphor 16 on the lower layer 15 side, and the yellow phosphor is mixed with the second phosphor. It is desirable to mix the phosphor 18 into the upper layer 17.

  As described above, the white illuminant 11 of the present embodiment uses the phosphor having a relatively wide excitation spectrum or a phosphor having an excitation spectrum overlapping with the emission spectrum of another phosphor as the first phosphor 16. The second phosphor 18 includes a phosphor that is included in the lower layer 15 on the bottom surface side 13 and has a relatively narrow excitation spectrum as compared with the first phosphor 16 and whose excitation spectrum does not overlap the emission spectrum of the first phosphor 16. The transparent resin part which consists of upper and lower two layers is provided in the upper layer 17 on the recess 13 opening side. The blue light emitted from the blue LED element 14 is partially absorbed by the first phosphor 16 and the second phosphor while passing from the lower layer 15 to the upper layer 17, and the respective phosphors emit fluorescence. These fluorescence and blue light are mixed and emitted as white light from the opening of the recess 13. At this time, by including only the first phosphor 15 having a relatively wide excitation spectrum in the lower layer 15, the first phosphor 15 may absorb the fluorescence from the other phosphors and lose the color balance. Absent. In addition, the second phosphor 18 included in the upper layer 17 emits fluorescence when excited by blue light. However, since the second phosphor 18 hardly absorbs the fluorescence emitted from the first phosphor 16, the second phosphor 18 passes through the upper layer 17. The emitted light is a mixed color light (white light) of the fluorescence emitted from the first phosphor 16, the fluorescence emitted from the second phosphor 18, and the blue light emitted from the blue LED element 14. ) Is emitted, and light absorption between the phosphors is difficult to occur. Therefore, white light with high color rendering as designed can be obtained.

Next, a method for manufacturing the white light emitter 11 of this embodiment will be described.
First, the base material 12 which has the recessed part 13 on a cup and in which the desired wiring pattern which consists of electrically conductive materials, such as copper, was formed in the surface is prepared.
Next, the blue LED element 14 is mounted on the bottom surface of the recess 13. The blue LED element 14 is fixed on one wiring extended on the bottom surface by solder or conductive paste, and one electrode terminal of the blue LED element 14 and the one wiring are electrically connected. The other electrode terminal of the blue LED element 14 and the other wiring are electrically connected by wire bonding using a gold thin wire or the like.
Next, a predetermined amount of a transparent resin in which the first phosphor 16 is dispersed at a predetermined concentration is filled in the recess 13 and cured. Although the curing conditions vary depending on the resin used, it is desirable that the curing is not completely performed for reasons such as preventing bubbles from being mixed.
After that, a predetermined amount of a transparent resin in which the second phosphor 18 is dispersed at a predetermined concentration is filled on the upper side, and the white phosphor 11 shown in FIG. 1 is obtained by complete curing.

  Note that the volume of each layer, the concentration of the phosphor, and the like vary depending on the characteristics of the phosphor used, the target emission color, the cup shape, and the like.

In the white light emitter 11 of this embodiment, the light emission colors of the individual white light emitters 11 to be manufactured are equal compared to the case where two types of phosphors are dispersed together in a transparent resin to provide a transparent resin portion. , Color variation can be reduced.
Since the white light emitter 11 of the present embodiment can obtain white light having a higher average color rendering index than when only one of the phosphors is used, it can be applied as a lighting device having high color rendering properties.

In addition, the said embodiment is a mere illustration of this invention, and this invention is not limited to this, A various change and correction are possible.
For example, in the above-described example, two types of phosphors and two layers of transparent resin portions are used. However, three or more types of phosphors and / or three or more layers of transparent resin portions may be used.
Further, in the above-described example, the surface mount package is illustrated, but the present invention can also be applied to a bullet-type LED described in Patent Document 1.

[Example 1]
A surface mount package having the structure shown in FIG. 1 was produced.
After mounting the blue LED in the concave part of the base material, put the transparent epoxy resin in which the red phosphor is dispersed in the concave part, fill the transparent epoxy resin in which the yellow phosphor is dispersed in the upper part, and cure the resin As shown in FIG. 1, the upper and lower transparent resin layers were formed, and the white light emitter of Example 1 was produced.

  For comparison, on the other hand, a transparent epoxy resin in which both a yellow phosphor and a red phosphor were dispersed was filled in the recess, and a white light emitter of Comparative Example 1 having a one-layer structure shown in FIG. 3 was produced.

The emission spectrum of the phosphor (P46Y3, SCS_Red) used for the production is shown in FIG. The excitation spectrum is shown in FIG.
FIG. 6 shows the excitation spectrum of the red phosphor and the emission spectrum of the yellow phosphor. As shown in FIG. 6, it can be seen that the emission wavelength of the yellow phosphor overlaps with the excitation range of the red phosphor.

Using these phosphors, 100 white light emitters of Example 1 and Comparative Example 1 were each produced, and the xy chromaticity of light emitted from each white light emitter was measured.
As a result, the standard deviation of xy chromaticity of Example 1 having a two-layer structure is 0.005 and 0.003, and Comparative Example 1 having a one-layer structure is 0.01 and 0.008. The superiority of was recognized. The color rendering properties were not significantly different between the two, and the average color rendering index was about 62 in both cases.

  As another effect, in the two-layer structure, the amount of phosphor necessary for one white light emitter is reduced. This is because, in the case of a single layer structure, yellow light emission is absorbed by the red phosphor, and in order to realize the same color as the two layer structure, it is necessary to fill a larger amount of yellow phosphor. is there. Furthermore, due to this effect, the light emission efficiency is different, resulting in higher light emission efficiency in the two-layer structure. This is because in the case of a single-layer structure, the ratio of red light emitted from the yellow phosphor is increased and the ratio of red emission increases, so that the blue LED is less efficient than the direct red color. .

[Example 2]
Next, what used three types of fluorescent substance as a white light-emitting body with high color rendering property was produced. The structure is not particularly shown.
After mounting the blue LED in the recess of the base material, a transparent epoxy resin in which the red phosphor is dispersed is put in the recess, and a transparent epoxy resin in which the yellow phosphor and the green phosphor are dispersed is filled on the upper side, The resin was cured to form two transparent resin layers on the upper and lower sides, and the white light emitter of Example 2 was produced.

  On the other hand, for comparison, a white phosphor of Comparative Example 2 having a single-layer structure was prepared by filling a recess with a transparent epoxy resin in which three types of yellow phosphor, red phosphor and green phosphor were dispersed.

The emission spectrum of the phosphor (P46Y3, SCS_Red, TG_Green) used for the production is shown in FIG. The excitation spectrum is shown in FIG.
FIG. 9 shows the excitation spectrum of the red phosphor and the emission spectra of the yellow phosphor and the green phosphor. As shown in FIG. 9, it can be seen that the yellow and green phosphors overlap the excitation region of the red phosphor.

Using these phosphors, 100 white light emitters of Example 2 and Comparative Example 2 were produced, respectively, and the xy chromaticities of light emitted from the individual white light emitters were measured.
As a result, the standard deviation of the xy chromaticity of Example 1 having a two-layer structure is 0.01 and 0.08, and the comparative example 2 of the one-layer structure is 0.02 and 0.015. The superiority of was recognized. The color rendering properties were not significantly different between the two, and the average color rendering index was about 90 for both.

Also in this example, as in Example 1, the effect of reducing the amount of phosphor used and the effect of improving the light emission efficiency were observed.
Note that the luminous efficiency is output luminous flux ÷ input power.

It is sectional drawing which shows one Embodiment of the white light-emitting body based on this invention. It is sectional drawing which shows an example of the conventional white light-emitting body. It is sectional drawing explaining the generation | occurrence | production cause of the color variation in the conventional high color rendering white light-emitting body. 3 is a diagram showing an emission spectrum of a phosphor used in Example 1. FIG. 2 is a diagram showing an excitation spectrum of a phosphor used in Example 1. FIG. It is a figure which shows the light emission and excitation spectrum of the fluorescent substance used in Example 1. FIG. 6 is a diagram showing an emission spectrum of a phosphor used in Example 2. FIG. 6 is a diagram showing an excitation spectrum of a phosphor used in Example 2. FIG. It is a figure which shows the light emission and excitation spectrum of the fluorescent substance used in Example 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... White light-emitting body, 12 ... Base material, 13 ... Recessed part, 14 ... Blue LED element, 15 ... Lower layer, 16 ... 1st fluorescent substance, 17 ... Upper layer, 18 ... 2nd fluorescent substance.

Claims (7)

A transparent resin in which a base material having a cup-shaped recess, a blue light emitting diode mounted on the bottom surface of the recess, and a phosphor filled in the recess and excited by blue light to emit visible light other than blue are dispersed A white light emitter having a portion,
At least two kinds of the phosphors are used, and the transparent resin portion is made into at least two layers having different phosphors, and is included in a lower layer provided on the bottom surface side of the concave portion among these layers. The white light-emitting body characterized in that the type of phosphor is the same as or less than the type of phosphor contained in the upper layer provided on the opening side of the recess.   2. The white light emission according to claim 1, wherein the phosphor contained in the lower layer has a wider excitation wavelength region than the phosphor contained only in the upper layer. body.   3. The excitation spectrum of the phosphor contained in the lower layer is at least partially overlapped with the emission spectrum of the phosphor contained only in the upper layer. The white light emitter described.   4. The white light-emitting body according to claim 1, wherein a blue light-emitting diode and two types of phosphors are used, and the average color rendering index is higher than when only one of the phosphors is used. .   One of said 2 types of fluorescent substance is a yellow fluorescent substance, and the other is a red fluorescent substance, The white light-emitting body in any one of Claims 1-4 characterized by the above-mentioned.   The blue color light emitting diode and three kinds of phosphors are used, and the average color rendering index is higher than the case where only one kind or two kinds of the phosphors are used. White illuminant. The illuminating device which has the white light-emitting body in any one of Claims 1-6 as a light source.

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