JP2014086696A - Light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently improve luminous efficiency while suppressing luminous loss caused by multistep excitation.SOLUTION: In a light-emitting device 10, an encapsulation resin body is separated into a resin body 5a and a resin body 5b. The resin body 5a contains a first phosphor of a shorter emission wavelength. On the other hand, the resin body 5b contains the first phosphor and a second phosphor of a longer emission wavelength.

Description

  The present invention relates to a light emitting device that emits light having a desired wavelength by exciting a phosphor in a sealing resin with light from a light emitting element.

  A light emitting diode (hereinafter referred to as an LED) is one of the most efficient light sources currently available. A typical example of a general LED is shown in FIG. FIG. 7 is a diagram schematically showing a cross section of a light emitting device 110 that is a general LED. As shown in FIG. 7, the light emitting device 110 includes a substrate 101, a pair of electrodes 104, a light emitting element 103, a translucent resin body 105, and a frame body 102.

  A light emitting element 103 is provided on the upper surface of the substrate 101. The light emitting element 103 is electrically connected to the electrode 104 through a bonding wire. A sealing resin body 105 is provided so as to cover the light emitting element 103 from above. Further, the frame body 102 surrounds the side surface of the sealing resin body 105.

  As a white light emitting device using the LED having the structure shown in FIG. 7 (light emitting device 110), a blue light emitting element (light emitting element 103) having an emission peak wavelength near 450 nm and a yellow fluorescence excited by the blue light emitting element are emitted. There is a white device that obtains white light by mixed color light emission of blue light emission and yellow light emission by a combination of YAG phosphors that emit light.

  The white LED device described above emits pseudo white light by a combination of blue light emission and yellow fluorescence which is a complementary color thereof. Such white light emission is inferior in red color reproducibility, resulting in poor color rendering. This pseudo white light emission is used for applications such as an electric bulletin board and a backlight that require only white light (appears white in design).

  On the other hand, if a white LED device is used for illumination, it is necessary to reproduce high-quality color rendering. By configuring the white LED device to emit white light obtained by mixing the three primary colors of light, red, green, and blue, a device with good color rendering can be provided. Such a device is disclosed in Patent Document 1, for example.

  A high color rendering white LED device that is currently widely used obtains white light by a blue light emitting element (light emitting element 103) and two phosphors that are excited by the blue light emitting element and emit green and red fluorescence. Yes. These two phosphors are mixed with a light-transmitting resin body (sealing resin body 105) such as a thermosetting epoxy resin or silicone resin, and are dispersed uniformly in the resin body, so that It is applied upward.

  However, when a plurality of phosphors having different emission colors are mixed and contained in the sealing resin body, a phenomenon in which the fluorescence emitted by one kind of phosphor is absorbed by another kind of phosphor occurs. This phenomenon is called so-called cascade excitation. If cascade excitation occurs, there arises a problem that the luminous efficiency of the encapsulating resin body is lowered.

  In the case of the high color rendering white LED device described above, first, blue light emitted from the light emitting element excites the green phosphor, whereby green light is fluorescent. Further, the green light is used as an excitation source for the red phosphor, whereby the red light is fluorescent. As described above, the configuration in which excitation is performed in multiple stages has a very large color conversion loss.

  Therefore, in order to improve the light emission efficiency of the device, technologies aiming to suppress loss due to multistage excitation by separating the green phosphor and the red phosphor into individual regions are disclosed in Patent Document 1 and Patent Document 2. It is disclosed. A light emitting device 120 disclosed in Patent Document 2 is shown in FIG. FIG. 8 is a diagram schematically showing a cross section of the light emitting device 120 disclosed in Patent Document 2. As shown in FIG. As shown in FIG. 7, the light emitting device 120 includes a substrate 101, a frame body 102, a light emitting element 103, a pair of electrodes 104, a translucent resin body 105a, and a translucent resin body 105b.

  In the light emitting device 120, two types of translucent resin bodies including different types of phosphors are provided. Specifically, the translucent resin body 105a includes a red phosphor, while the translucent resin body 105b includes a green phosphor. Thus, in the light emitting device 120, basically, the green phosphor and the red phosphor are separated into individual regions. In addition to this, Patent Document 2 describes that the translucent resin body 105b may contain a smaller amount of red phosphor.

JP 2004-327492 A (released on November 18, 2004) JP-A-2005-244226 (published on September 5, 2005)

  However, the light emitting device 120 according to Patent Document 2 has a problem that the light emission efficiency cannot be improved well. This problem will be described below with reference to FIG.

  FIG. 9 is a graph showing the emission spectrum 121 of the light emitting device 110 shown in FIG. 7 and the emission spectrum 131 of the light emitting device 120 shown in FIG. As shown in FIG. 9, in the light emitting device 120, the light emission intensity at 620 nm, which is the light emission band of the red phosphor, is lower than that in the light emitting device 110. Therefore, it is impossible to realize the light emission intensity necessary for the mixed spectrum (color temperature around 3000 k).

  In the light emitting device 120, in order to realize the light emission intensity necessary for the mixed spectrum, it is necessary to further increase the area of the translucent resin body 105a that is a region including the red phosphor. However, if it does in this way, the area of translucent resin body 105b which is an area | region containing red fluorescent substance and green fluorescent substance will become small. As a result, the intensity of green light becomes insufficient.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a light emitting device capable of sufficiently improving the light emission efficiency while suppressing light emission loss due to multi-step excitation.

  In order to solve the above problems, a light-emitting device according to one embodiment of the present invention includes a substrate, at least one light-emitting element provided over the top surface of the substrate, and a sealing resin that seals the light-emitting element. The sealing resin includes a first sealing resin including a first phosphor having a shorter emission wavelength, the first phosphor, and a more emission wavelength. And a second sealing resin containing a long second phosphor.

  According to one embodiment of the present invention, there is an effect that light emission efficiency can be sufficiently improved while suppressing light emission loss due to multistage excitation.

It is a schematic diagram showing the cross section of the light-emitting device which concerns on the 1st Embodiment of this invention. It is the figure which contrasted the emission spectrum of the light-emitting device which concerns on the 1st Embodiment of this invention, and the emission spectrum of the light-emitting device currently used widely. It is a top view of the light-emitting device which concerns on the 2nd Embodiment of this invention. It is a top view of the other light-emitting device which concerns on the 2nd Embodiment of this invention. It is a schematic diagram showing the cross section of the light-emitting device which concerns on the 3rd Embodiment of this invention. It is a schematic diagram showing the cross section of the light-emitting device which concerns on the 4th Embodiment of this invention. It is a schematic diagram showing the cross section of the light-emitting device which concerns on a well-known technique. 10 is a schematic diagram illustrating a cross section of a light-emitting device described in Patent Document 2. FIG. It is the figure which contrasted the emission spectrum of the light-emitting device of patent document 2, and the emission spectrum of the light-emitting device which concerns on a well-known technique.

  Hereinafter, embodiments of the present invention will be described in detail.

Embodiment 1
(Configuration of Light Emitting Device 10)
An embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic view showing a cross section of a light emitting device 10 according to the first embodiment of the present invention. The light emitting device 10 includes a substrate 1, a frame 2, a light emitting element 3, a pair of electrodes 4, a resin body 5a (first sealing resin), and a resin body 5b (second sealing resin). .

  A light emitting element 3 is provided on the upper surface of the substrate 1. A pair of electrodes 4 is also provided on the mounting surface of the light emitting element 3 on the substrate 1. Wiring is formed on the substrate 1, and the light emitting element 3 is electrically connected to the pair of electrodes 4 by bonding wires via the wiring. The frame body 2 is a reflector (reflecting plate) formed from a white resin or the like, and surrounds the resin body 5a and the resin body 5b.

  The light emitting element 3 is a light source in the light emitting device 10. In the present embodiment, the light emitting element 3 is an LED. However, the present invention is not limited to this, and a phosphor, an electroluminescence element, a semiconductor light source, or the like may be used.

(Characteristics of the light emitting device 10)
In a conventional white light emitting device, like the light emitting device 110, two types of phosphors are mixed in a sealing resin body such as a thermosetting epoxy resin or silicone resin and are uniformly dispersed in the resin body. In this state, it is applied above the blue light emitting element. On the other hand, the light emitting device 10 according to the present embodiment is characterized in that the sealing resin body is separated into two types of regions and the types of phosphors included in the respective sealing resin bodies are different. have.

  Specifically, as shown in FIG. 1, the sealing resin body includes a resin body 5a and a resin body 5b. The resin body 5a includes a single first phosphor having a shorter wavelength of excitation light. Phosphor The resin body 5a contains only the first phosphor. On the other hand, the sealing resin body 5b includes two types of phosphors, that is, a first phosphor having a shorter wavelength and a second phosphor having a longer wavelength of excitation light.

  The resin body 5 a and the resin body 5 b are formed by being separately applied to the substrate 1. As an example of this coating method, there is a method of applying a sealing resin body for each region after a frame is previously made of a highly viscous permeable resin body using a dispenser. As another example, there is a method in which a sealing resin body is applied to each region after a pattern using a liquid repellent is printed on a substrate in advance. However, these methods are not limited.

  In the present embodiment, the light emitting element 3 is a blue light emitting element that emits blue light having a peak wavelength in the vicinity of 450 nm. The first phosphor is a green phosphor having a peak wavelength near 530 nm. On the other hand, the second phosphor is a red phosphor having a peak wavelength near 620 nm.

(Emission spectrum)
FIG. 3 is a graph showing an emission spectrum of the light emitting device 10 according to the present embodiment and an emission spectrum of the light emitting device 110 according to a known technique. A curve 11 in the figure represents the emission spectrum of the light emitting device 10, while a curve 111 represents the emission spectrum of the light emitting device 110.

  As described above, the resin body 5a of the light emitting device 20 is composed of a resin body containing a green phosphor. On the other hand, the resin body 5b is composed of a resin body in which a green phosphor and a red phosphor are mixed. As shown in FIG. 3, by dividing the sealing resin body into two regions, the spectrum of the green light of the light emitting device 20 is increased, and the blue light emitted from the light emitting element 3 by the green phosphor is efficiently colored. You can see that it is converted.

  Table 1 below shows the optical evaluation results of the light emitting device 10 and the light emitting device 110.

  The light emitting device 10 has a color temperature of 7257 K, a chromaticity x of 0.301, a chromaticity y of 0.323, a radiant flux of 8.35 W, a luminous flux of 2404 lm, and a color rendering property Ra of 80.3. On the other hand, the color temperature of the light emitting device 20 is 7470 K, the chromaticity x is 0.296, the chromaticity y is 0.328, the radiant flux is 8.97 W, the luminous flux is 2624 lm, and the color rendering property Ra is 77.8.

  As shown in Table 1, the radiant flux of the light emitting device 10 according to the present embodiment is improved by about 7.4% and the luminous flux is improved by about 9.2% compared with the light emitting device 110 according to the known technology. doing. In addition, unlike the light emitting device 120 according to Patent Document 2, the light emission intensity in the red region (620 nm) does not decrease compared to the light emitting device 110.

  In this way, the sealing resin body is separated into two regions, the resin body 5a and the resin body 5b, the resin body 5a contains only the first phosphor (green phosphor), and the resin body 5b By including the first phosphor and the second phosphor (red phosphor), sufficient emission intensity is achieved in the mixed emission spectrum without suppressing the emission intensity in the red region (620 nm). As a result, it is possible to suppress multi-stage excitation with a large color conversion loss, and to obtain a white LED device (light emitting device 10) with high efficiency and high color rendering.

[Embodiment 2]
The second embodiment according to the present invention will be described below with reference to FIGS. In addition, the same number is attached | subjected to the component which has the function similar to the component which concerns on Embodiment 1, and the description is abbreviate | omitted. In the present embodiment, differences from the first embodiment will be mainly described.

  FIG. 3 is a top view illustrating a configuration example of the light emitting device 20 according to the present embodiment. FIG. 5 is a top view illustrating a configuration example of the light emitting device 30 according to the present embodiment.

  The light emitting device 20 and the light emitting device 30 are the same as those in the first embodiment except that the formation region of the sealing resin bodies (the resin body 5a and the resin body 5b) of the light emitting device 10 (FIG. 1) according to the first embodiment is changed. The light emitting device 10 has the same configuration. In the light emitting device 20, the resin bodies 5 a and the resin bodies 5 b that seal the light emitting elements 3 are provided alternately and linearly. As a result, it is possible to mix lights having different color temperatures that have undergone color conversion through the resin body 5a and the resin body 5b.

  The light emitting device 30 has a structure in which the resin body 5a for sealing the light emitting element 3 is applied to the substrate in a dot shape, and then the remaining region is applied with the resin body 5b. It becomes possible to mix lights having different color temperatures, which have undergone color conversion through the resin bodies 5b. In the light emitting device 30, the resin body 5b may be provided on the substrate 1 in a dot shape.

  As a method of separately applying the resin body 5a and the resin body 5b in a stripe shape or a dot shape, for example, a dam is prepared in advance with a highly viscous transparent resin body, and then the resin body 5a and the resin body 5b are applied to each region. There is a technique. There is also a method in which a resin body 5a and a resin body 5b are applied to each region after a pattern using a liquid repellent is printed on a substrate in advance.

  In the case where the resin body 5a and the resin body 5b are separately applied in a stripe shape or a dot shape, it is not desirable to apply them in a very fine manner. If they are finely painted, color conversion may occur when light emitted from a certain region passes through adjacent regions having different phosphor concentrations. As a result, so-called crosstalk occurs, and there is a concern that the color temperature may deviate greatly from the target color temperature. Therefore, it is preferable to arrange each phosphor region (resin body 5a and resin body 5b) so as to minimize the boundary line between the regions of the sealing resin body.

[Embodiment 3]
The following will describe another embodiment of the present invention with reference to FIG. In addition, the same number is attached | subjected to the component which has the function similar to the component which concerns on Embodiment 1 or 2, and the description is abbreviate | omitted. In the present embodiment, differences from the second embodiment will be mainly described.

  FIG. 5 is a cross-sectional view illustrating a configuration example of the light emitting device 50 according to the present embodiment. As shown in this figure, the light emitting device 50 is the same as the light emitting device 20 of Embodiment 2 except that the coating thickness of the sealing resin body of the light emitting device 20 (FIG. 4) according to Embodiment 2 is changed. It is the same configuration.

  The light emitting device 40 has a thickness (coating thickness) in a direction perpendicular to the substrate 1 in a resin body 5b including a red phosphor having a long excitation light wavelength and a green phosphor having a short excitation light wavelength. ) Is smaller than the thickness (coating thickness) in the direction perpendicular to the substrate 1 in the resin body 5a including only the green phosphor having a short wavelength of excitation light.

  Thereby, the green light emitted from the region (resin body 5a) containing a lot of green phosphors having a short wavelength of excitation light passes through the region (resin body 5b) containing a lot of red phosphors having a long wavelength of excitation light. This makes it possible to further suppress the crosstalk that causes color conversion.

[Embodiment 4]
The following will describe another embodiment of the present invention with reference to FIG. In addition, the same number is attached | subjected to the component which has the function similar to the component which concerns on Embodiment 1, and the description is abbreviate | omitted. In the present embodiment, differences from the second embodiment will be mainly described.

  FIG. 6 is a cross-sectional view illustrating a configuration example of the light emitting device 50 according to the present embodiment. As shown in this figure, the light-emitting device 50 is the light-emitting device of Embodiment 2 except that the distribution of each phosphor in the sealing resin body of the light-emitting device 20 (FIG. 4) according to Embodiment 2 is changed. 20 is the same configuration.

  FIG. 6 is a cross-sectional view illustrating a configuration example of the light emitting device 50 according to the present embodiment. As shown in this figure, in the light emitting device 50, the height of the region including the green phosphor and the red phosphor in the resin body 5b is smaller than the height of the region including only the green phosphor of the resin body 5a. It is characterized by that. In other words, each phosphor in the resin body 5b has settled deeper on the substrate 1 side than each phosphor in the resin body 5a.

  Thereby, the probability that the green light emitted from the region containing a lot of green phosphors having a short excitation light wavelength adjacent to the region containing the red phosphors is used as the excitation source of the red phosphors is lowered. As a result, crosstalk can be suppressed.

(Summary)
As described above, a light-emitting device according to one embodiment of the present invention is provided.
A substrate,
At least one light emitting element provided on the upper surface of the substrate;
A light emitting device including a sealing resin for sealing the light emitting element,
The sealing resin is
A first sealing resin containing a single first phosphor having a shorter emission wavelength;
A second sealing resin including the first phosphor and a second phosphor having a longer emission wavelength is provided.

  According to said structure, sufficient light emission intensity | strength can be implement | achieved in a mixed emission spectrum, without suppressing the light emission intensity | strength (for example, red light) emitted from 2nd fluorescent substance. As a result, light emission efficiency is sufficiently improved while suppressing light emission loss due to multistage excitation. Therefore, it is possible to realize a white light emitting device with high efficiency and high color rendering.

  In the light-emitting device according to one embodiment of the present invention, it is preferable that the first sealing resin and the second sealing resin are provided alternately and on a straight line.

  According to the above configuration, light with different color temperatures emitted from each region of the sealing resin body can be mixed, so that color unevenness of light emitted from the light emitting device can be reduced.

  In the light-emitting device according to one embodiment of the present invention, the thickness of the second sealing resin in a direction perpendicular to the substrate is more than that of the substrate in the first sealing resin. The thickness is preferably smaller than the thickness in the vertical direction.

  According to the above configuration, the crosstalk generated when light emitted from a certain region passes through an adjacent region can be further reduced, so that multistage excitation can be further suppressed.

  In the light-emitting device according to one embodiment of the present invention, the height of the region including the first phosphor and the second phosphor in the second sealing resin is further higher than the first phosphor. It is preferable that the height of the region including the first phosphor in the sealing resin is smaller.

  According to the above configuration, the crosstalk generated when light emitted from a certain region passes through an adjacent region can be further reduced, so that multistage excitation can be further suppressed.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention. Furthermore, a new technical feature can be formed by combining the technical means disclosed in each embodiment.

  The present invention can be used for various light emitting devices such as light emitting diodes (LEDs).

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Frame 3 Light emitting element 4 Electrode 5a Resin body (1st sealing resin)
5b Resin body (second sealing resin)
10 Light emitting device

Claims (4)

A substrate,
At least one light emitting element provided on the upper surface of the substrate;
A light emitting device including a sealing resin for sealing the light emitting element,
The sealing resin is
A first sealing resin containing a single first phosphor having a shorter emission wavelength;
A light-emitting device comprising: the first phosphor and a second sealing resin including a second phosphor having a longer emission wavelength.   The light emitting device according to claim 1, wherein the first sealing resin and the second sealing resin are provided alternately and on a straight line.   The thickness of the second sealing resin in a direction perpendicular to the substrate is smaller than the thickness of the first sealing resin in a direction perpendicular to the substrate. Item 3. The light emitting device according to Item 1 or 2.   The height of the region including the first phosphor and the second phosphor in the second sealing resin includes the first phosphor in the first sealing resin. The light emitting device according to claim 1, wherein the light emitting device is smaller than a height of the region.

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