JP2008071806A - Light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting device which can emit white light exhibiting good color rendering properties, high luminance and stabilized white balance. <P>SOLUTION: The light emitting device comprises an LED 3 emitting ultraviolet light beams 8 and 16, a blue phosphor 10 excited by the ultraviolet light beams 8, 16, 17 and 19 to emit blue light beams Bo, Br and B, a red phosphor 13 excited by the ultraviolet light beams 16, 19 and the blue light beams Bo, Br, B to emit red light beam R, and a green phosphor 14 excited by the ultraviolet light beams 16, 19 and the blue light beams Bo, Br, B to emit green light beam G. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light emitting device using an LED (Light Emitting Diode).

Conventionally, a light-emitting device that emits white light using an LED and a phosphor is known. This light-emitting device obtains pseudo-white light by using light of two colors of blue and yellow in order to reliably and easily achieve a desired balance of light and obtain stable light emission characteristics (for example, Patent Document 1). reference).
Japanese Patent No. 3645422

  However, since the conventional light emitting device obtains pseudo white light by synthesizing only two colors of light, it is easy to mix with a predetermined balance and the white balance is stabilized, but color rendering is not preferable. There is a problem. Therefore, there is a problem that it is not suitable for indoor illumination light, for example, and can be used only for limited applications such as an electric bulletin board.

  Therefore, the present invention can generate light of three colors, red (R), green (G), and blue (B), to obtain white light with good color rendering, high luminance, and stable white balance. Provided is a light-emitting device that can be used.

In order to solve the above problems, the present invention provides an LED that emits ultraviolet light, a first phosphor that is excited by the ultraviolet light and emits first light, and the ultraviolet light and the first light. Light emission comprising: a second phosphor that is excited to emit second light; and a third phosphor that is excited by the ultraviolet light and the first light to emit third light. Device.
With this configuration, the first phosphor is excited by the ultraviolet light emitted by the LED to generate the first light, and the second light is generated by both the first light and the ultraviolet light. The third phosphor can be excited to generate the second and third lights.

The present invention also includes an outer phosphor layer including the second phosphor and the third phosphor, and the first phosphor, and is disposed between the outer phosphor layer and the LED. A light emitting device comprising the inner phosphor layer.
With this configuration, ultraviolet light is prevented from being absorbed or scattered by the second and third phosphors before reaching the first phosphor.

  In the present invention, the ultraviolet light has a peak wavelength in a range of 350 nm to 410 nm. By comprising in this way, the selection range of LED which can be used as a light source can be expanded.

According to the present invention, the outer phosphor layer includes the first phosphor, and the inner phosphor layer is disposed at a distance from the outer phosphor layer.
By comprising in this way, the ultraviolet light which permeate | transmitted the inner side fluorescent substance layer can be absorbed by the 1st fluorescent substance of an outer side fluorescent substance layer, and a 1st light can be emitted also in an outer side fluorescent substance layer.
Moreover, the ultraviolet light which permeate | transmitted the inner side fluorescent substance layer can be reflected by the surface of an outer side fluorescent substance layer, can reach the 1st fluorescent substance of an inner side fluorescent substance layer again, and can emit 1st light.
Furthermore, the first light emitted from the first phosphor of the inner phosphor layer toward the outer phosphor layer and reflected by the surface of the outer phosphor layer, and the inner side from the first phosphor of the outer phosphor layer The first light emitted toward the phosphor layer is reflected by the surface of the inner phosphor layer. These first lights can reach the outer phosphor layer and excite the second and third phosphors to emit the second and third lights.
Further, the first phosphor of the outer phosphor layer is excited by the ultraviolet light that is transmitted through the inner phosphor layer, reflected by the surface of the outer phosphor layer, and again reflected by the surface of the inner phosphor layer. Can emit light. Furthermore, the second and third phosphors can be excited by both the ultraviolet light and the generated first light.

Further, the present invention is characterized in that the first light is blue light, the second light is red light, and the third light is green light.
By configuring in this way, the first phosphor is excited by the ultraviolet light emitted from the LED to emit blue light, and the second and third phosphors are excited by the blue light and the ultraviolet light, respectively. Emits red light and green light.

According to the present invention, the first light has a peak wavelength in a range of 455 nm to 485 nm and a half width of at least 25 nm, and the second light has a peak wavelength in a range of 610 nm to 645 nm and a half width. It is at least 55 nm, and the third light has a peak wavelength in a range of 520 nm to 545 nm and a half width of at least 40 nm.
With this configuration, the first light (blue light) and third light (green light), and the third light (green light) and second light (red light) spectra overlap each other. Can be increased.

In the present invention, the first phosphor is mainly composed of CaSiO ₃ .SiO ₂ : Eu, I, and the second phosphor is composed mainly of SrCaS: Eu, I. In addition, the third phosphor is mainly composed of SrGa ₂ S ₄ : Eu, Pr.
With this configuration, the specific gravity of the second phosphor and the third phosphor can be set to approximately 3.62 g / cm ^{3 which} is the same for both. In addition, the wavelength range of light for exciting each phosphor may be approximately 325 nm to 450 nm for the first phosphor, approximately 400 nm to 575 nm for the second phosphor, and approximately 300 nm to 525 nm for the third phosphor. it can.

According to the present invention, the second and third phosphors are excited by both the first light and the ultraviolet light that has not been absorbed by the first phosphor, so that it is excited only by the first light. It can be excited more strongly than the case.
Therefore, the second and third lights can be generated more efficiently and their luminance can be increased, so that synthesized light with high luminance can be emitted to the outside.

In addition, the LED has a characteristic that the wavelength of emitted light varies due to heat generated by light emission. However, by using an LED that emits ultraviolet light, even if the wavelength of the ultraviolet light emitted by the LED fluctuates, the ultraviolet light can hardly be recognized by the naked eye, so it has little effect on the wavelength of the synthesized light emitted to the outside. Never give. In addition, since the wavelength of the light emitted from the phosphor hardly changes even if the wavelength of the input wave that excites the phosphor fluctuates, the wavelength of the synthesized light emitted to the outside is hardly affected.
Therefore, stable synthetic light can be obtained.

In addition, according to the present invention, it is possible to prevent the ultraviolet light from being absorbed or scattered by the second and third phosphors before reaching the first phosphor to make it difficult to reach the first phosphor. Therefore, the excitation rate of the first phosphor can be improved. Since the second and third phosphors are excited by the first light emitted from the first phosphor, the excitation rates of the second and third phosphors are not reduced.
Therefore, the brightness of the synthesized light can be improved.
Further, the rate at which the ultraviolet light is converted into the first light and the rate at which the first light and the ultraviolet light are converted into the second and third lights are stabilized.
Therefore, the wavelength of the synthesized light emitted from the light emitting device is more stable and easy to control.

Further, according to the present invention, the ultraviolet light transmitted through the inner phosphor layer can be absorbed by the first phosphor in the outer phosphor layer, and the first phosphor can be emitted also in the outer phosphor layer. The brightness of the first light can be improved. Further, the second light and the third phosphor in the same outer phosphor layer can be excited by the first light, and the luminance of the second and third light can be improved.
In addition, since the inner phosphor layer is disposed at a distance from the outer phosphor layer, the ultraviolet light transmitted through the inner phosphor layer is reflected by the surface of the outer phosphor layer, and again the inner phosphor layer The first light can be emitted by reaching one phosphor. Therefore, ultraviolet light can be converted into the first light more efficiently. Therefore, the brightness of the first light increases.

Furthermore, the first light emitted from the first phosphor of the inner phosphor layer toward the outer phosphor layer and reflected by the surface of the outer phosphor layer, and the inner side from the first phosphor of the outer phosphor layer The first light emitted toward the phosphor layer is reflected by the surface of the inner phosphor layer, and the second and third phosphors of the outer phosphor layer are excited to produce the second and third lights. Can be issued. Therefore, the brightness of the second and third lights can be improved.
Further, the first phosphor of the outer phosphor layer is excited by the ultraviolet light that is transmitted through the inner phosphor layer, reflected by the surface of the outer phosphor layer, and again reflected by the surface of the inner phosphor layer. Since light can be emitted, the luminance of the first light can be improved.
Further, since the second and third phosphors can be excited by both the ultraviolet light and the generated first light, the luminance of the second and third lights can be increased. .
Therefore, the brightness of the synthesized light emitted from the light emitting device can be improved.

  In addition, according to the present invention, the range of selection of LEDs that can be used as light sources can be widened, so that LEDs that are light sources can be easily obtained.

  Further, according to the present invention, the first, second, and third phosphors generate light of three colors of blue (B), green (G), and red (R), so that white light with good color rendering properties can be obtained. Can be obtained. Further, if the first light is blue light, the wavelength of the first light is close to the wavelength of the ultraviolet light, so that the second and third phosphors excited by the ultraviolet light and the first light can be easily obtained. Can get to.

  In addition, according to the present invention, it is possible to increase the portion where the spectrums of blue light and green light and green light and red light overlap with each other, and thus white light with a flatter spectrum waveform can be obtained.

  Further, according to the present invention, the first phosphor that emits blue light when excited by ultraviolet light by using the phosphor represented by the above chemical formula as the first, second, and third phosphors. Can be obtained. In addition, a second phosphor that is excited efficiently by ultraviolet light and blue light and emits green light can be obtained. Furthermore, a third phosphor that is excited by ultraviolet light and blue light and emits red light can be obtained.

Next, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, an LED 3, which is a semiconductor element that emits ultraviolet light having a wavelength of about 405 nm, is installed on a substrate 2 at the bottom of the light emitting device body 1. Here, in this embodiment, ultraviolet light is defined as light having a peak wavelength of 350 to 410 nm. The LED 3 is connected to an electrode (not shown) on the substrate 2 and further connected to an external power source or the like. An embankment-like reflector 4 is provided on the substrate 2 with a slight gap from the LED 3, and surrounds the LED 3 except for the opening 5 opened in a direction substantially perpendicular to the substrate 2. The outer wall 6 of the reflector 4 is substantially perpendicular to the substrate 2, and the inner wall 7 has a funnel shape that gradually increases in diameter from the substrate 2 side toward the opening 5 side. The surface of the reflector 4 is made of a material having a high light reflectance. The light emitted radially from the LED is reflected by the surface of the inner wall 7 of the reflector 4 and converted into light substantially parallel to the optical axis of the reflector 4.

  A transparent resin that transmits ultraviolet light 8 emitted from the LED 3 is filled around the LED 3 inside the reflector 4 to form a first resin layer 9. On the first resin layer 9, a film-like inner phosphor layer 11 is disposed substantially in parallel with the substrate 2 and in contact with the inner wall 7 of the reflector 4. The illustrated lower surface of the inner phosphor layer 11 is disposed in contact with the LED 3 and the resin layer 9. The inner phosphor layer 11 is formed by dispersing a first phosphor 10 that emits blue light Bo when excited (hereinafter referred to as blue phosphor 10) in a resin. Further, a second resin layer 12 is formed on the inner phosphor layer 11 by filling the above resin. Further, on the second resin layer 12, a film-like outer phosphor layer 15 is similarly arranged in a state separated from the inner phosphor layer 11. The outer phosphor layer 15 includes a second phosphor 13 that emits red light R when excited (hereinafter referred to as red phosphor 13) and a third phosphor 14 that emits green light G (hereinafter green). (Referred to as phosphor 14) and the blue phosphor 10 described above are dispersed in a resin.

Here, in this embodiment, the following products manufactured by Sarnoff Corporation of the United States are used as the phosphor. Bermuda-465 (chemical formula CaSiO ₃ · SiO ₂ : Eu, I) is used as the blue phosphor 10, Hawaii-630 (chemical formula SrCaS: Eu, I) is used as the red phosphor 13, and Maui-535 is used as the green phosphor 14. (Chemical formula SrGa ₂ S ₄ : Eu, Pr) is used. Details of these phosphors are shown in Table 1 and FIG.

FIG. 2 shows a spectrum diagram of excitation light and output light of a phosphor, which is normalized with reference to a peak value. As shown in FIGS. 2 (B1), (G1), and (R1), although there is a difference in excitation intensity, the wavelength of the light that excites each phosphor 10, 14, 13 (hereinafter referred to as excitation light) is blue. The phosphor 10 has a relatively wide width, which is approximately 325 nm to 450 nm, the green phosphor 14 is approximately 300 nm to 525 nm, and the red phosphor 13 is approximately 400 nm to 575 nm.
The wavelength of the excitation light that excites the blue phosphor 10 most strongly is about 370 to 380 nm as shown in FIG. 2B1, and the wavelengths that excite the green phosphor 14 and the red phosphor 13 most strongly are shown in FIG. As shown in (G1) and (R1), it is about 470 to 480 nm.

  Further, as shown in FIGS. 2 (B2), (G2), and (R2), the half-value widths Wb, Wg, and spectrum of light emitted from the phosphors 10, 14, and 13 (hereinafter referred to as output light) are excited. Wr is about 25 nm, about 40 nm, and about 55 nm, respectively. As shown in FIG. 2 (B2), the peak wavelength of the output light of the blue phosphor 10 is in the range of about 455 nm to 485 nm (for example, about 465 nm). Similarly, as shown in FIGS. 2 (G1) and (R1), the peak wavelength of the output light of the green phosphor 14 is in the range of about 520 to 545 nm (for example, about 535 nm), and the peak of the output light of the red phosphor 13 The wavelength is in the range of about 610 nm to 645 nm (for example, 630 nm).

Next, the operation and effect of this embodiment will be described.
As shown in FIG. 1, ultraviolet light 8 and 16 having a wavelength of about 405 nm is generated by the LED 3 installed on the electrode on the substrate 2, and the inner phosphor layer 11 is irradiated with the ultraviolet light 8 and 16.
The irradiated ultraviolet light 8 is absorbed by the blue phosphor 10 in the inner phosphor layer 11 to excite the blue phosphor 10 and output blue light Bo having a spectrum peak in the range of about 455 nm to 485 nm as output light. To emit. Other ultraviolet light 16 that is not absorbed by the blue phosphor 10 passes through the inner phosphor layer 11 and reaches the outer phosphor layer 15.

The ultraviolet light 16 reaching the blue phosphor 10 in the outer phosphor layer 15 excites the blue phosphor 10 to generate blue light B.
A part of the ultraviolet light 16 reaching the outer phosphor layer 15 reaches the red phosphor 13 and the green phosphor 14 and is absorbed. Since the absorbed ultraviolet light 16 has a wavelength of about 405 nm, the green phosphor 14 is excited to generate green light G as shown in FIG. 2 (G1). Similarly, as shown in FIG. 2 (R1), the red phosphor 13 is excited to generate red light R.
The ultraviolet light 16 that has not been absorbed by the phosphors 10, 13 and 14 is emitted to the outside.

In addition, the blue light Bo emitted by the blue phosphor 10 in the inner phosphor layer 11 passes through the second resin layer 12 and is dispersed in the outer phosphor layer 15. To be absorbed or scattered.
The blue light Bo absorbed by the red phosphor 13 and the green phosphor 14 in the outer phosphor layer 15 excites the phosphors 13 and 14 to generate the red light R and the green light G and emits them to the outside. Let
The blue light Bo that has not been absorbed by the phosphors 10, 13, and 14 in the outer phosphor layer 15 passes through the outer phosphor layer 15 and is emitted to the outside as blue light B.

A part of the blue light B emitted by the blue phosphor 10 in the outer phosphor layer 15 is absorbed by the red phosphor 13 and the green phosphor 14 existing in the same outer phosphor layer 15, and each phosphor 13, 14 is excited, and red light R and green light G are emitted to the outside, respectively.
The blue light B that has not been absorbed by the red phosphor 13 and the green phosphor 14 is emitted to the outside. Of the blue light B, the blue light Br emitted toward the second resin layer 12 is reflected at the interface between the inner phosphor layer 11 and the second resin layer 12 and reaches the outer phosphor layer 15 again. .

A part of the blue light Bo emitted from the blue phosphor 10 of the inner phosphor layer 11 and reflected at the interface between the outer phosphor layer 15 and the second resin layer 12 is emitted from the outer phosphor layer 15. Similar to the blue light Br, the light is reflected at the interface between the inner phosphor layer 11 and the second resin layer 12 and reaches the outer phosphor layer 15 again.
Part of the blue light Br and the blue light Bo that has been reflected at the interface between the inner phosphor layer 11 and the second resin layer 12 and reached the outer phosphor layer 15 is absorbed by the red phosphor 13 and the green phosphor 14. Then, the phosphors 13 and 14 are excited to emit the red light R and the green light G to the outside.
Some of the other blue light Br and Bo that are not absorbed by the phosphors 10, 13, and 14 are emitted to the outside as blue light B.

Further, the ultraviolet light 17 that is a part of the ultraviolet light 16 that has passed through the inner phosphor layer 11 and reached the outer phosphor layer 15 is reflected by the interface between the outer phosphor layer 15 and the second resin layer 12. Then, the light reaches the inner phosphor layer 11 and excites the blue phosphor 10 to generate blue light Bo.
Further, in the ultraviolet light 17, the ultraviolet light 19 reflected at the interface between the inner phosphor layer 11 and the second resin layer 12 excites the phosphors 10, 13, and 14 in the outer phosphor layer 15. As a result, blue light B, red light R, and green light G are generated in the phosphors 10, 13, and 14, respectively.
All the red light R, green light G and blue light B generated in this way are combined and emitted as white light to the outside of the light emitting device.

  Therefore, according to the above-described embodiment, the use of the LED 3 that emits the ultraviolet light 8 or 16 as the light emitting element enables the ultraviolet light to be generated even if the wavelength of the ultraviolet light 8 or 16 emitted by the LED 3 fluctuates due to the heat generated by the LED 3. Can hardly be recognized by the naked eye, the ultraviolet light 16 emitted to the outside does not affect the white balance of the white light emitted by the light emitting device.

  In addition, by using the blue phosphor 10 having a relatively wide spectrum of excitation light wavelength, even if the wavelength of the ultraviolet light emitted by the LED 3 fluctuates within the above range due to the heat generated by the LED 3, the ultraviolet light 8 , 16 are allowed to change by the blue phosphor 10, and can be converted into stable blue light Bo, Br, B.

Further, as shown in FIGS. 2 (G1) and (R1), the wavelengths of the excitation light spectrum peaks Pg and Pr of the green phosphor 14 and the red phosphor 13 are the blue light Bo, Br, Since the phosphors 13 and 14 are close to the wavelengths of B and B, they are strongly excited by the blue light Bo, Br and B. At the same time, it is also excited by the ultraviolet light 16 having a wavelength of 405 nm transmitted through the inner phosphor layer 11. Therefore, it is possible to generate red light R and green light G with higher efficiency and higher luminance.
Therefore, it is possible to improve the luminance of the red light R and the green light G constituting the white light and improve the luminance of the white light emitted from the light emitting device.

Further, since the red phosphor 13 and the green phosphor 14 having the same specific gravity are used, when the phosphor layers are formed by mixing them and dispersing in the resin, the phosphors 13 and 14 are made of resin. It can be uniformly dispersed without being biased inside.
Therefore, it is possible to prevent the balance between the red light R and the green light G, which are output lights, from being different for each product, and to stabilize the white balance.

Further, the inner phosphor layer 11 in which the blue phosphor 10 is dispersed in the resin is formed, and the outer phosphors in which the phosphors 14, 13 and 10 of three colors of red, green, and blue are mixed and dispersed in the resin. By separating the inner phosphor layer 11 from the body layer 15 and arranging it on the LED 3 side, the red light 13 and the green phosphor 14 before the ultraviolet light 8 emitted by the LED 3 reaches the blue phosphor 10. Is prevented from being absorbed or scattered.
Therefore, the excitation rate of the blue phosphor 10 can be improved. Furthermore, since the red phosphor 13 and the green phosphor 14 are excited by the blue light Bo emitted from the blue phosphor 10, the excitation rates of the red phosphor 13 and the green phosphor 14 are not reduced.
Therefore, the brightness of red light R, green light G, and blue light B can be increased, and the brightness of white light can be improved.

Further, since the ultraviolet light 8 is prevented from being absorbed or scattered by the red phosphor 13 and the green phosphor 14 before reaching the blue phosphor 10, the rate at which the ultraviolet light 8 is converted into the blue light Bo is increased. The red light R and the green light G generated by converting the blue light Bo and the ultraviolet light 16 into the red phosphor 13 and the green phosphor 14 are stabilized.
Therefore, since the ratio of red light R, green light G, and blue light B constituting white light is stabilized, the white balance of white light emitted from the light emitting device can be easily controlled, and the white balance can be stabilized. it can.

Further, since the blue phosphor 10 is provided in the outer phosphor layer 15, a part of the ultraviolet light 16 that has passed through the inner phosphor layer 11 and reached the blue phosphor 10 in the outer phosphor layer 15 is blue phosphor. 10 is excited to generate blue light B. Therefore, the luminance of the blue light B can be improved by effectively using the ultraviolet light 16 that has not been converted into the blue light Bo by the inner phosphor layer 11.
Further, part of the blue light B emitted by the blue phosphor 10 in the outer phosphor layer 15 is absorbed by the red phosphor 13 and the green phosphor 14 existing in the same outer phosphor layer 15, and each phosphor. 13 and 14 are excited to generate red light R and green light G, respectively. Therefore, the luminance of the red light R and the green light G can be improved as compared with the case where the blue phosphor 10 is not provided on the outer phosphor layer 15.
Therefore, the luminance of the red light R, the green light G, and the blue light B constituting the white light can be improved, and the luminance of the white light emitted from the light emitting device can be improved.

Further, since the inner phosphor layer 11 is disposed at a distance from the outer phosphor layer 15, the blue light Br emitted by the blue phosphor 10 in the outer phosphor layer 15 and the second phosphor layer 15 and the second phosphor layer 15 are arranged. Part of the blue light Bo reflected at the interface with the resin layer 12 is reflected at the interface between the inner phosphor layer 11 and the second resin layer 12 and reaches the outer phosphor layer 15 again. Therefore, each of the blue light Br and the blue light Bo excites the phosphors 13 and 14 to generate red light R and green light G. Therefore, the luminance of the red light R and the green light G can be improved as compared with the case where the inner phosphor layer 11 is not disposed at a distance from the outer phosphor layer 15.
Further, the blue light Br that has not been absorbed by the phosphors 13 and 14 and part of the blue light Bo that is reflected at the interface between the outer phosphor layer 15 and the second resin layer 12 are emitted to the outside. Therefore, the brightness of the blue light B emitted to the outside can be improved.
Therefore, the luminance of the red light R, the green light G, and the blue light B constituting the white light can be improved, and the luminance of the white light emitted from the light emitting device can be improved.

  Furthermore, the ultraviolet light 17 that is a part of the ultraviolet light 16 that has passed through the inner phosphor layer 11 is reflected by the interface between the outer phosphor layer 15 and the second resin layer 12 and reaches the inner phosphor layer 11. Since the blue phosphor 10 is excited to generate the blue light Bo, the ultraviolet light 16 can be converted into the blue light B more efficiently. Then, the blue light Bo generates red light R and green light G as described above, and a part thereof is emitted as blue light B to the outside. Therefore, the brightness of the red light R, the green light G, and the blue light B constituting the white light can be improved, and the brightness of the white light emitted from the light emitting device can be improved.

Further, the ultraviolet light 19 which is a part of the ultraviolet light 17 is reflected by the interface between the inner phosphor layer 11 and the second resin layer 12 and reaches the outer phosphor layer 15 to excite the blue phosphor 10. Blue light B is generated. At the same time, the ultraviolet light 17 and the blue light B generated thereby excite the red phosphor 13 and the green phosphor 14 to generate red light R and green light G. Therefore, the ultraviolet light 16 can be converted into red light R, green light G, and blue light B more efficiently.
Therefore, the luminance of white light emitted from the light emitting device can be further improved as compared with the case where the inner phosphor layer 11 is not spaced from the outer phosphor layer 15.

The present invention is not limited to the above-described embodiment, and the phosphor is not limited to a product made by Sarnoff as long as the phosphor has similar characteristics. For example, (Sr, Ca) S: Eu, (Ca, Sr) 2Si5N8: Eu, or CaAlSiN3: Eu may be used as the red phosphor. Similarly, SrGa2S4: Eu, Ca3Sc2Si3O12: Ce, or SrSi2O2N2: Eu may be used as the green phosphor. Similarly, (Sr, Ca, Ba, Mg) 10 (PO4) 6Cl2: Eu or (Ba, Sr) MgAl10O17: Eu may be used as the blue phosphor.
Further, the specific gravity of the blue phosphor may be equal to that of other phosphors. Moreover, although the case where the 1st resin layer was provided around LED was demonstrated in the said embodiment, as shown in FIG. 8, as a structure which provides a fluorescent substance layer directly instead of a 1st resin layer, as shown in FIG. Good. In this case, the lifetime of the light emitting device can be extended by reducing the number of resin layers that are easily deteriorated by ultraviolet light. Further, the first and second resin layers need not be resin as long as they transmit ultraviolet light, blue light, green light, and red light. A plurality of LEDs may be provided on the substrate.

In the light emitting device body 1 of FIG. 1 described in the above embodiment, the blue phosphor 10 is dispersed in a silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., for LED sealing) at a concentration of 20%, and the inner side is 100 μm thick. The phosphor layer 11 was formed.
Further, a layer having a thickness of 100 μm formed by dispersing the blue phosphor 10 in the same silicone resin at a concentration of 40% is used as an inner layer, and the red phosphor 13 is used in the same silicone resin at a concentration of 26% and the green phosphor 14 is formed. A 180 μm-thick layer formed by dispersing at a concentration of 40% was used as an outer layer, and these layers were laminated to form a multi-layer type outer phosphor layer 15.
In this state, a current of 40 mA is applied to LED3 made by Mitsubishi Electric Industries Co., Ltd. (flip chip type, dimensions: 350 μm in length × 350 μm in width, peak wavelength of output light: 405 nm) in series with two chips. 1 generated white light.

As a result, the point E1 (x, y) = (0.29, 0...) Close to the point W (x, y) = (0.33, 0.33) indicating perfect white in the chromaticity coordinates shown in FIG. White light from the bluish color of 31) was obtained. At this time, the luminance of white light was 2.0 lumens.
Further, as shown in FIG. 4, the spectrum of white light was such that red light R, green light G, and blue light B were distributed in a well-balanced manner except for ultraviolet light. That is, as shown in FIG. 2, by using the phosphors 10, 14, and 13 having relatively wide half-value widths Wb, Wg, and Wr, the light beams R, G, and B of each color overlap each other, and the wavelength distribution is increased. White light with a flatter color rendering was obtained.

In Example 2 shown in FIG. 5, the inner phosphor layer 11 is removed from the light emitting device main body 1 of FIG. The other configuration is the same as that of the light emitting device main body 1 of FIG.
In the light emitting device main body 201 of FIG. 5, as in Example 1, the blue phosphor 210 was dispersed in a silicone resin at a concentration of 40% to form an inner layer having a thickness of 100 μm. Then, a red phosphor 213 and a green phosphor 214 were dispersed in the same silicone resin at a concentration of 26% and a concentration of 40%, respectively, to form an outer layer having a thickness of 180 μm. Furthermore, they were laminated to form a multi-layer type outer phosphor layer 215.
In this state, a current of 40 mA was applied to the LED 203 similar to that in Example 1, and white light was generated in the light emitting device main body 201.

  As a result, white light indicating a point E2 (x, y) = (0.29, 0.25) slightly separated from the point W indicating perfect white in the chromaticity coordinates shown in FIG. 3 was obtained. The brightness of the white light at this time was 1.6 lumen.

In Example 3 shown in FIG. 6, the inner phosphor layer 11 is brought into close contact with the outer phosphor layer 15 in the light emitting device main body 1 of FIG. 1, and the blue phosphor 10 is removed from the outer phosphor layer 15, thereby red phosphor 13. And only the green phosphor 14 is dispersed in the resin. The other configuration is the same as that of the light emitting device main body 1 of FIG.
In the light emitting device main body 301 of FIG. 6, as in Example 1, the blue phosphor 310 was dispersed in a silicone resin at a concentration of 40% to form an inner phosphor layer 311 having a thickness of 100 μm. In addition, an outer phosphor layer 315 having a thickness of 180 μm was formed by dispersing red phosphor 313 at a concentration of 25% and green phosphor 314 at a concentration of 20% in the same silicone resin.
In this state, a current of 40 mA was applied to the LED 303 similar to that in Example 1, and white light was generated in the light emitting device main body 301.

  As a result, white light indicating a point E3 (x, y) = (0.28, 0.29) slightly separated from the point W indicating perfect white in the chromaticity coordinates shown in FIG. 3 was obtained. At this time, the brightness of white light was 1.8 lumens.

In Example 4 shown in FIG. 7, an intermediate phosphor layer 418 having the same configuration as that of the inner phosphor layer 11 is formed between the outer phosphor layer 15 and the second resin layer 12 in the light emitting device main body 1 of FIG. 1. Then, the blue phosphor 10 is removed from the outer phosphor layer 15, and only the red phosphor 13 and the green phosphor 14 are dispersed in the resin. The other configuration is the same as that of the light emitting device main body 1 of FIG.
In the light emitting device main body 401 of FIG. 7, as in Example 1, the blue phosphor 410 was dispersed in a silicone resin at a concentration of 20% to form an inner phosphor layer 411 having a thickness of 100 μm. Further, an outer phosphor layer 415 having a thickness of 180 μm was formed by dispersing the red phosphor 413 at a concentration of 20% and the green phosphor 414 at a concentration of 20% in the same silicone resin. Then, the blue phosphor 310 was dispersed in the same silicone resin at a concentration of 40% to form an intermediate phosphor layer 418 having a thickness of 100 μm.
In this state, a current of 40 mA was applied to the LED 403 similar to that in Example 1, and white light was generated in the light emitting device main body 401.

  As a result, white light indicating a point E4 (x, y) = (0.25, 0.27) slightly separated from the point W indicating perfect white in the chromaticity coordinates shown in FIG. 3 was obtained. The brightness of the white light at this time was 1.6 lumen.

In the light emitting device body 1 of FIG. 1, as in Example 1, the blue phosphor 10 was dispersed in a silicone resin at a concentration of 20% to form the inner phosphor layer 11 having a thickness of 100 μm. In addition, a layer having a thickness of 100 μm formed by dispersing the blue phosphor 10 in the same silicone resin at a concentration of 40% is used as an inner layer, and the red phosphor 13 and the green phosphor 14 in the same silicone resin at a concentration of 35% and 35%, respectively. A 180 μm-thick layer formed by dispersing at a concentration of 20% was used as an outer layer, and these layers were laminated to form a multi-layer type outer phosphor layer 15.
In this state, the LED 3 similar to Example 1 was made into a total of 6 chips of 3 chips in series and 2 series, and a current of 100 mA was applied to generate white light in the light emitting device body 1.

As a result, the point E5 (x, y) = (0.35, 0) closest to the point W (x, y) = (0.33, 0.33) showing perfect white in the chromaticity coordinates shown in FIG. .33) white light was obtained. The brightness of the white light at this time was 13.0 lumens.
In addition, even when the current value applied to the LED 3 is changed from 20 mA to 100 mA, it shows a point close to the point W (0.33, 0.33) indicating perfect white color, and has a very stable white light emission characteristic. Indicated. That is, even when the applied current was changed to 20 mA, the chromaticity coordinates were (x, y) = (0.35, 0.33), and there was no change from when 100 mA was applied. Further, even when the voltage was increased and the applied current was 200 mA, the chromaticity coordinates were (x, y) = (0.34, 0.33), and there was almost no change from when 100 mA was applied.
FIG. 9 shows a spectrum of white light when the applied current is changed. In the figure, i is a solid line, i is 50 mA, ii is an alternate long and short dash line is 100 mA, iii is a dashed line is 150 mA, and iv is an alternate current of 200 mA.
As shown in FIG. 9, in all applied currents, ultraviolet light was efficiently converted, and white light with good color rendering properties in which red light R, green light G, and blue light B were distributed in a well-balanced manner could be obtained.

  As described above, in Examples 1 to 5, white light with sufficient white balance was obtained. In addition, in terms of brightness and white balance, Example 5 described in detail in the above embodiment gave the best results.

It is sectional drawing which shows the conceptual structure of the light-emitting device in embodiment of this invention. FIG. 3 is a spectrum diagram of excitation light and output light of a phosphor according to an embodiment of the present invention, where (B1) and (B2) are blue phosphors, (G1) and (G2) are green phosphors, and (R1), ( R2) is a spectrum diagram of excitation light and output light of a red phosphor. It is a chromaticity coordinate diagram of white light in Examples 1 to 4 of the present invention. It is a spectrum figure of white light in Example 1 of the present invention. It is sectional drawing which shows the conceptual structure of the light-emitting device in Example 2 of this invention. It is sectional drawing which shows the conceptual structure of the light-emitting device in Example 3 of this invention. It is sectional drawing which shows the conceptual structure of the light-emitting device in Example 4 of this invention. It is sectional drawing which shows the conceptual structure of the modification of the light-emitting device of FIG. It is a spectrum figure of white light in Example 5 of the present invention.

Explanation of symbols

1 Light emitting device body 3 LED
8 Ultraviolet light 10 Blue phosphor (first phosphor)
11 Inner phosphor layer 13 Red phosphor (second phosphor)
14 Green phosphor (third phosphor)
15 Outer phosphor layer 16 Ultraviolet light 17 Ultraviolet light 19 Ultraviolet light B Blue light (first light)
Bo Blue light (first light)
Br Blue light (first light)
R Red light (second light)
G Green light (third light)

Claims (7)

An LED that emits ultraviolet light;
A first phosphor that is excited by the ultraviolet light and emits a first light;
A second phosphor that is excited by the ultraviolet light and the first light and emits a second light;
A light emitting device comprising: a third phosphor that is excited by the ultraviolet light and the first light and emits third light. An outer phosphor layer comprising the second phosphor and the third phosphor;
The light emitting device according to claim 1, further comprising an inner phosphor layer that includes the first phosphor and is disposed between the outer phosphor layer and the LED. The outer phosphor layer includes the first phosphor,
The light emitting device according to claim 2, wherein the inner phosphor layer is disposed at a distance from the outer phosphor layer.   The light emitting device according to claim 1, wherein the first light is blue light, the second light is red light, and the third light is green light. .   The light emitting device according to claim 1, wherein the ultraviolet light has a peak wavelength in a range of 350 nm to 410 nm.   The first light has a peak wavelength in a range of 455 nm to 485 nm and a half width of at least 25 nm, and the second light has a peak wavelength in a range of 610 nm to 645 nm and a half width of at least 55 nm, 5. The light emitting device according to claim 4, wherein the third light has a peak wavelength in the range of 520 nm to 545 nm and a half width of at least 40 nm. The first phosphor is mainly composed of CaSiO ₃ .SiO ₂ : Eu, I, and the second phosphor is composed mainly of SrCaS: Eu, I. The light-emitting device according to claim 1, wherein the phosphor is mainly composed of SrGa ₂ S ₄ : Eu, Pr.

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