JP2017152666A - Light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting device with a shallow dip, which has light emission spectra close to those of solar light.SOLUTION: A light-emitting device 1 according to an embodiment of the present invention comprises: a first light-emitting element 11; a phosphor 15; and a second light-emitting element 12 having a peak wavelength between peak wavelengths of two peaks forming the deepest dip in combined light emission spectra of the first light-emitting element 11 and phosphor 15.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a light emitting device.

  2. Description of the Related Art Conventionally, a light emitting device that includes an LED (Light Emitting Diode) and a phosphor and emits white light is known (see, for example, Patent Documents 1 and 2). In such a light emitting device, the combined emission spectrum of the LED and the phosphor forms a white light spectrum.

International Publication No. 2012/108065 International Publication No. 2012/144087

  However, due to the characteristics of phosphors, the wavelength ranges of the absorption spectrum and the emission spectrum are separated. For this reason, in order to increase the absorption efficiency of excitation light, a light emitting element having an emission wavelength far from the emission spectrum of the phosphor must be used as the excitation light source.

  For this reason, in a synthetic emission spectrum of a light emitting element and a phosphor, and a pale white spectrum having a particularly high color temperature such as daylight color, a deep depression (dip) is formed between the emission wavelength of the light emitting element and the emission wavelength of the phosphor. ) Exists. The presence of such a deep dip becomes an obstacle to bringing the emission spectrum of the light emitting device close to the spectrum of sunlight (natural light).

  One of the objects of the present invention is to provide a light-emitting device having a light emission spectrum with a shallow dip and close to sunlight.

  One embodiment of the present invention provides the following light-emitting devices [1] to [7] in order to achieve the above object.

[1] A first light emitting element, a phosphor, and a second wavelength having a peak wavelength between two peak wavelengths forming the deepest dip in the combined emission spectrum of the first light emitting element and the phosphor. A light emitting device.

[2] The light emitting device according to the above [1], wherein a deviation of a peak wavelength of the second light emitting element from a wavelength at a bottom of the deepest dip is within 2 nm.

[3] The light emitting device according to [1], wherein the second light emitting element includes a plurality of light emitting elements having different wavelengths.

[4] A first sealing material that seals the first light-emitting element and a second sealing material that seals the second light-emitting element, and the phosphor includes: The light emitting device according to any one of [1] to [3], which is included in the first sealing material.

[5] The first sealing material is in contact with the second sealing material, and the refractive index of the first sealing material is lower than the refractive index of the second sealing material. The light emitting device according to any one of [1] to [4].

[6] An annular seal in which the first sealing material and the second sealing material are in contact, and one of the first sealing material and the second sealing material has an annular planar shape. The light emitting device according to any one of [1] to [5], wherein the light emitting device is a material and the other is a sealing material surrounded by the annular sealing material.

[7] The light-emitting device according to any one of [1] to [6], wherein the second light-emitting element is used as a transmission unit for optical communication.

  According to the present invention, it is possible to provide a light emitting device that has a shallow dip and has an emission spectrum close to that of sunlight.

FIG. 1A is a top view of the light emitting device according to the embodiment. FIG. 1B is a vertical cross-sectional view of the light-emitting device cut along the line AA in FIG. 2A and 2B show examples of a synthetic emission spectrum of the first light emitting element and the phosphor. FIG. 3A is a top view of a modification of the light emitting device according to the embodiment. FIG. 3B is a vertical cross-sectional view of the light-emitting device cut along the line BB in FIG. 4A to 4C are vertical sectional views showing manufacturing steps of the light emitting device according to the embodiment. FIG. 5 is a perspective view showing the first sealing material before bonding when the patterned first sealing material is bonded to a substrate. 6A to 6D are vertical cross-sectional views illustrating modifications of the manufacturing process of the light emitting device according to the embodiment. FIG. 7A is a graph schematically showing a difference in responsiveness with respect to the frequency of the electric signal between the light emitting element and the phosphor. FIG. 7B is a graph schematically showing a difference in response speed between the light emitting element and the phosphor.

Embodiment
(Configuration of light emitting device)
FIG. 1A is a top view of the light emitting device 1 according to the embodiment. FIG. 1B is a vertical cross-sectional view of the light emitting device 1 cut along the line AA in FIG.

  The light emitting device 1 includes a substrate 10, a first light emitting element 11 and a second light emitting element 12 installed on the substrate 10, a first sealing material 13 for sealing the first light emitting element 11, It has the 2nd sealing material 14 which seals the 2nd light emitting element 12, and the particulate-form fluorescent substance 15 contained in the 1st sealing material 13. FIG.

  The first light emitting element 11 functions as an excitation light source for the phosphor 15, and the color mixture of the emission color of the first light emitting element 11 and the emission color of the phosphor 15 becomes white. Moreover, the fluorescent substance 15 may be comprised from several types of fluorescent substance from which a wavelength differs. In this case, a light emitting element that emits ultraviolet light may be used as the first light emitting element 11, and the mixed color of the light emission colors of the plurality of phosphors may be white.

  The second light-emitting element 12 is used to fill the deepest dip in the combined emission spectrum of the first light-emitting element 11 and the phosphor 15 and to bring the emission spectrum of the light-emitting device 1 closer to the emission spectrum of sunlight.

  For this reason, the second light emitting element 12 has a peak wavelength between two peak wavelengths (wavelengths at the peak apexes) that form the deepest dip in the combined emission spectrum of the first light emitting element 11 and the phosphor 15. Have The deviation of the peak wavelength of the second light emitting element 12 from the wavelength at the bottom of the deepest dip is preferably within 2 nm.

  The second light emitting element 12 may be composed of a plurality of light emitting elements having different wavelengths. In this case, the peak wavelengths of all the light emitting elements constituting the second light emitting element 12 have a peak wavelength between the peak wavelengths of the two peaks forming the deepest dip.

  2A and 2B show examples of a synthetic emission spectrum of the first light emitting element 11 and the phosphor 15.

2A, the first light-emitting element 11 is a blue LED having an emission wavelength of 450 nm, the phosphor 15 is a green phosphor made of Lu ₃ Al ₅ O ₁₂ : Ce ³⁺ , and Y ₃ Al ₅ O ₁₂ : It is a synthetic spectrum in the case of a yellow phosphor made of Ce ³⁺ and a red phosphor made of CaAlSiN ₃ : Eu ²⁺ .

  The wavelength of the bottom of the deepest dip (indicated by an arrow) in the combined emission spectrum of the first light emitting element 11 and the phosphor 15 shown in FIG. 2A is approximately 481 nm. Of the two peaks forming the deepest dip, the peak wavelength on the short wavelength side (the peak of the emission spectrum of the first light emitting element 11) is about 452 nm, and the peak on the long wavelength side (phosphor) The peak wavelength of 15 emission spectra is approximately 577 nm.

  In this case, a light emitting element having a peak wavelength larger than 452 nm and within a range R smaller than 777 nm is used as the second light emitting element 12, and the deviation from the peak wavelength of 481 nm is within 2 nm, that is, 479 nm to 483 nm. It is preferable that a light emitting element is used as the second light emitting element 12. When a plurality of light emitting elements having different light emission wavelengths are used as the second light emitting element 12, the peak wavelength of any light emitting element is within the range R.

In FIG. 2B, the first light-emitting element 11 is a violet LED having an emission wavelength of 405 nm, and the phosphor 15 is a blue phosphor made of (Sr, Ca, Ba) ₁₀ (PO ₄ ) Cl ₂ : Eu ^2+. _{, (Si, Al) 6 (} O, N) 8: a green phosphor made of ^{Eu 2+,} CaAlSiN _3: is a synthetic spectrum when a red phosphor consisting of ^{Eu 2+.}

  The wavelength of the bottom of the deepest dip (indicated by an arrow) in the combined emission spectrum of the first light emitting element 11 and the phosphor 15 shown in FIG. 2B is approximately 422 nm. Of the two peaks forming the deepest dip, the peak wavelength on the short wavelength side (peak of the emission spectrum of the first light emitting element 11) is about 402 nm, and the peak on the long wavelength side (phosphor) The peak wavelength of 15 emission spectra is approximately 454 nm.

  In this case, a light emitting element having a peak wavelength larger than 402 nm and within a range R smaller than 454 nm is used as the second light emitting element 12, and the deviation from the peak wavelength of 422 nm is within 2 nm, that is, 420 nm or more and 424 nm or less. It is preferable that a light emitting element is used as the second light emitting element 12. When a plurality of light emitting elements having different light emission wavelengths are used as the second light emitting element 12, the peak wavelength of any light emitting element is within the range R.

  The phosphor 15 may be included in both the first sealing material 13 and the second sealing material 14, but when it is included in the second sealing material 14, the second light emitting element Since the amount of absorption of the light emitted by the phosphor 15 increases, it becomes difficult to set the emission wavelength and emission intensity of the second light emitting element 12 for filling the deepest dip. For this reason, it is preferable that the phosphor 15 is included only in the first sealing material 13.

  When the first sealing material 13 and the second sealing material 14 are in contact with each other, the refractive index of the first sealing material 13 is preferably lower than the refractive index of the second sealing material 14. In this case, since light is less likely to be transmitted from the second sealing material 14 to the first sealing material 13, the fluorescence contained in the first sealing material 13 of the light emitted from the second light emitting element 12. The amount of absorption by the body 15 can be suppressed.

  The substrate 10 is, for example, a wiring substrate or a lead frame insert substrate.

  The first light emitting element 11 and the second light emitting element 12 are, for example, LED chips having a chip substrate and a crystal layer including a light emitting layer and a clad layer sandwiching the light emitting layer. The first light-emitting element 11 and the second light-emitting element 12 may be face-up type LED chips with the crystal layer facing upward, or face-down type LED chips with the crystal layer facing downward. May be. Moreover, light emitting elements other than LED chips, such as a laser diode, may be used.

  The first light emitting element 11 and the second light emitting element 12 are connected to a conductive member (not shown) such as a wiring or a lead frame included in the substrate 10, and the first light emitting element 11 and the second light emitting element 12 are connected via the conductive member. Power is supplied to each light emitting element 12 independently.

  The first sealing resin 13 and the second sealing resin 14 are made of a transparent resin such as a silicone resin or an epoxy resin, for example.

  In addition, since the first light-emitting element 11 and the second light-emitting element 12 are independently supplied with power, the light emission intensity can be arbitrarily adjusted. For this reason, the emission spectrum of the light emitting device 1 can be made closer to sunlight.

  Note that the number, shape, arrangement, and the like of the first sealing material 13 and the second sealing material 14 are not particularly limited, such as the number and arrangement of the first light-emitting element 11 and the second light-emitting element 12.

  In the configuration example of the light emitting device of this embodiment shown in FIG. 1, the first sealing material 13 is an annular sealing material having an annular planar shape, and the second sealing material 14 is an annular first material. Surrounded by the sealing material 13.

  3A shows the arrangement of the first light-emitting element 11 and the second light-emitting element 12 in the light-emitting device 1 shown in FIG. 1, and the first sealing material 13 and the second sealing material. It is a top view of the light-emitting device 2 which has the structure which reversed arrangement | positioning of 14. FIG. FIG. 3B is a vertical cross-sectional view of the light emitting device 1 cut along the line BB in FIG.

  In the configuration example of the light emitting device of this embodiment shown in FIG. 3, the second sealing material 14 is an annular sealing material having an annular planar shape, and the first sealing material 13 is an annular second material. Surrounded by the sealing material 14. 3 is an annular sealing material that is made of the same material as the first sealing material 13 and seals the first light-emitting element 11, and includes an annular second sealing material. A sealing material surrounding the stopper 14 may be added. Further, the annular sealing material is made of the same material as the second sealing material 14 so as to surround the annular sealing material that seals the first light emitting element 11, and seals the second light emitting element 12. A material may be formed. The number of the annular sealing material for sealing the first light emitting elements 11 and the annular sealing material for sealing the second light emitting elements 12 that are alternately provided in this way is not limited.

  For example, when the second light emitting element 12 includes a plurality of light emitting elements having different wavelengths, a configuration including a plurality of second light emitting elements 12 such as the configuration of the light emitting device 2 is employed.

(Manufacturing process of light emitting device)
Below, an example of the manufacturing process of the light-emitting device 1 is shown.

  4A to 4C are vertical cross-sectional views illustrating manufacturing steps of the light emitting device 1 according to the embodiment.

  First, as shown in FIG. 4A, the first light emitting element 11 and the second light emitting element 12 are installed on the substrate 10.

  Next, as shown in FIG. 4B, the first light emitting element 11 is sealed with the first sealing material 13 including the phosphor 15. The first sealing material 13 is formed by a method in which the first sealing material 13 patterned in advance is bonded to the substrate 10 or by potting.

  FIG. 5 is a perspective view showing the first sealing material 13 before bonding when the patterned first sealing material 13 is bonded to the substrate 10. The first sealing material 13 is patterned on a sheet-like base material 20 made of PET or the like.

  Next, as shown in FIG. 4C, the resin is embedded in the region surrounded by the first sealing material 13 by potting to form the second sealing material 14.

  6A to 6D are vertical sectional views showing a modification of the manufacturing process of the light emitting device 1 according to the embodiment. In this modified example, the order of forming the first sealing material 13 and the second sealing material 14 is reversed as compared to the manufacturing steps shown in FIGS.

  First, as shown in FIG. 6A, the first light emitting element 11 and the second light emitting element 12 are installed on the substrate 10.

  Next, as shown in FIG. 6B, the second light emitting element 12 is sealed with the second sealing material 14. The second sealing material 14 is formed by a method in which the second sealing material 14 patterned in advance is bonded to the substrate 10 or potting.

  Next, as shown in FIG. 6C, an annular dam 16 is formed so as to surround the installation area of the first light emitting element 11. The dam 16 is made of a resin such as a silicone resin or an epoxy resin, and may include a white dye such as titanium oxide.

  Next, as shown in FIG. 6D, a resin containing phosphor 15 is embedded in a region between the dam 16 and the second sealing material 14 by potting to form the first sealing material 13. To do. The formation of the dam 16 may be omitted, but the formation of the dam 16 makes it easy to control the shape of the first sealing material 13 formed by potting.

  In the case of manufacturing the light emitting device 2 described above, the first light emitting element 11 and the second light emitting element in the steps shown in FIGS. 4A to 4C and FIGS. 6A to 6D. 12 may be reversed and the steps for the first sealing material 13 and the second sealing material 14 may be reversed.

(Modification of light emitting device)
Hereinafter, an example in which the light emitting device 1 is used as an optical transmitter of an optical communication system will be described.

  The second light emitting element 12 can be used as a transmission unit for optical communication. For example, a signal modulated at high speed for communication is sent from the controller outside the light emitting device 1 to the second light emitting element 12, and the second light emitting element 12 is caused to emit light based on the signal to perform communication. In this case, the light emitting device 1 functions as an optical transmitter of the illumination and transmission / reception system.

  For example, an Si sensor or an image sensor such as a camera mounted on a smartphone as a standard is used as the optical communication photodetector (reception unit). As a specific example, for example, the light-emitting device 1 is a downlight used in a store, and transmits product information to a customer's smartphone by communication using the second light-emitting element 12.

  When the emission wavelength of the first light emitting element 11, that is, the excitation wavelength of the phosphor 15 is a wavelength in the purple or ultraviolet region, the emission wavelength of the second light emitting element 12 is 420 nm as shown in FIG. Because it is in the region of low visibility, front and rear, there is almost no effect such as flickering on the eyes even if the light intensity fluctuates by using the second light emitting element 12, and communication is performed while suppressing the influence on the illumination function. The optical signal can be superimposed.

  FIG. 7A is a graph schematically showing a difference in responsiveness with respect to the frequency of an electric signal between a light emitting element which is an LED chip and a phosphor. As shown in FIG. 7A, the limit frequency at which the phosphor excited by the light emitted by the light emitting element can respond is lower than the limit frequency at which the light emitting element can respond to an electrical signal. That is, the cutoff frequency of the phosphor is lower than that of the light emitting element. This indicates that the phosphor has a slower response speed than the light emitting element and is not suitable for communication.

  FIG. 7B is a graph schematically showing a difference in response speed between the light emitting element which is an LED chip and the phosphor. As shown in FIG. 7B, the waveform of the phosphor is not suitable for communication because it largely collapses from the waveform of the electric signal as compared with the waveform of the light emitting element and becomes noise of the optical signal.

  For this reason, when the fluorescence of the phosphor is mixed with the light emission of the second light emitting element 12 for communication, the accuracy of communication is lowered. Therefore, the second sealing material 14 that does not include the phosphor 15 is sealed. It is preferable to use the second light emitting element 12 for communication.

(Effect of embodiment)
According to the above embodiment, the second light-emitting element 12 for filling the deepest dip in the combined light emission spectrum of the first light-emitting element 11 and the phosphor 15 has an emission spectrum close to sunlight. The light emitting device 1 can be provided. Further, the second light emitting element 12 can also be used as a transmission unit for optical communication.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention. In addition, the constituent elements of the above-described embodiment can be arbitrarily combined without departing from the spirit of the invention.

  For example, when the deepest dip in the combined emission spectrum of the first light emitting element 11 and the phosphor 15 is formed by the peaks of the two phosphors 15, that is, the dip other than the dip on the shortest wavelength side is the most. Even in a deep case, the above embodiment can be applied. Even in this case, a light emitting element having an emission wavelength capable of filling the deepest dip is used as the second light emitting element 12.

  Moreover, said embodiment does not limit the invention which concerns on a claim. In addition, it should be noted that not all the combinations of features described in the embodiments are essential to the means for solving the problems of the invention.

DESCRIPTION OF SYMBOLS 1 Light-emitting device 10 Board | substrate 11 1st light emitting element 12 2nd light emitting element 13 1st sealing resin 14 2nd sealing resin 15 Phosphor

Claims (7)

A first light emitting element;
A phosphor,
A second light emitting element having a peak wavelength between two peak wavelengths forming the deepest dip in the combined emission spectrum of the first light emitting element and the phosphor;
A light emitting device. The deviation of the peak wavelength of the second light emitting element from the wavelength at the bottom of the deepest dip is within 2 nm.
The light emitting device according to claim 1. The second light emitting element is composed of a plurality of light emitting elements having different wavelengths.
The light emitting device according to claim 1. A first sealing material for sealing the first light emitting element;
A second sealing material for sealing the second light emitting element;
Further comprising
The phosphor is included in the first sealing material.
The light-emitting device of any one of Claims 1-3. The first sealing material and the second sealing material are in contact with each other;
The refractive index of the first sealing material is lower than the refractive index of the second sealing material;
The light-emitting device of any one of Claims 1-4. The first sealing material and the second sealing material are in contact with each other;
One of the first sealing material and the second sealing material is an annular sealing material having an annular planar shape, and the other is a sealing material surrounded by the annular sealing material.
The light emitting device according to claim 1. The second light emitting element is used as a transmission unit for optical communication.
The light emitting device according to claim 1.

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