JP6728869B2 - Light emitting device - Google Patents

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 the phosphor, the wavelength bands of the absorption spectrum and the emission spectrum are separated. Therefore, in order to increase the absorption efficiency of the excitation light, a light emitting element having an emission wavelength far from the emission spectrum of the phosphor has to be used as the excitation light source.

Therefore, in the combined emission spectrum of the light-emitting element and the phosphor, particularly in the white-white spectrum having a high color temperature such as daylight color, a deep depression (dip) between the emission wavelength of the light-emitting element and the emission wavelength of the phosphor ) Exists. The presence of such a deep dip is 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 shallow dip and an emission spectrum close to that of sunlight.

In order to achieve the above object, one aspect of the present invention provides a light emitting device of the following [1] to [7].

[1] and the first light emitting element with ultraviolet or ultraviolet region emitting a first light emission spectrum, a blue phosphor emitting a second light emission spectrum in the blue region, and the first emission spectrum the A second light emitting element that emits light of a third emission spectrum having a peak wavelength between the peak wavelength of the purple or ultraviolet region and the peak wavelength of the blue region of the combined emission spectrum formed by the second emission spectrum. When having a second light emitting element is light of the third emission spectrum emitted is modulated by signal for optical communication, 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 of the bottom of the deepest dip is within 2 nm.

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

[4] The phosphor further includes a first encapsulant for encapsulating the first light-emitting element and a second encapsulant for encapsulating the second light-emitting element. 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 and the second sealing material are in contact with each other, 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 [ 4 ] .

[6] An annular sealing in which the first sealing material and the second sealing material are in contact with each other, and one of the first sealing material and the second sealing material has an annular planar shape. The light emitting device according to the above [ 4 ] or [ 5 ], which is a material and the other is a sealing material surrounded by the annular sealing material.

[7] The phosphor further includes a green phosphor and a red phosphor, and the second light emitting element forms the deepest dip as the dip. The peak of the first light emitting element and the blue phosphor. The light emitting device according to any one of [1] to [6] above, which has a peak wavelength between the peak wavelengths of the peaks .

According to the present invention, it is possible to provide a light emitting device having a shallow dip and 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 taken along the line segment AA of FIG. FIGS. 2A and 2B show examples of combined emission spectra 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 taken along the line BB of FIG. 3A. 4A to 4C are vertical cross-sectional views showing a manufacturing process 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 the substrate. 6A to 6D are vertical cross-sectional views showing a modified example of the manufacturing process of the light emitting device according to the embodiment. FIG. 7A is a graph schematically showing the difference in the responsivity of the light emitting element and the phosphor with respect to the frequency of the electric signal. FIG. 7B is a graph schematically showing the difference in response speed between the light emitting element and the phosphor.

[Embodiment]
(Structure 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 taken along the line segment 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 that are installed on the substrate 10, and a first sealing material 13 that seals the first light emitting element 11. It has the 2nd sealing material 14 which seals the 2nd light emitting element 12, and the particulate fluorescent substance 15 contained in the 1st sealing material 13.

The first light emitting element 11 functions as an excitation light source for the phosphor 15, and the color mixture of the light emitting color of the first light emitting element 11 and the light emitting color of the phosphor 15 becomes white. Further, the phosphor 15 may be composed of a plurality of types of phosphors having different wavelengths. In this case, a light emitting element that emits ultraviolet light may be used as the first light emitting element 11, and the color mixture of the 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 light emission spectrum of the first light emitting element 11 and the phosphor 15 to bring the light emission spectrum of the light emitting device 1 closer to the light emission spectrum of sunlight.

Therefore, the second light-emitting element 12 has a peak wavelength between two peak wavelengths (wavelengths at the peak peaks) 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 of 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 forming the second light emitting element 12 have a peak wavelength between the peak wavelengths of the two peaks forming the deepest dip.

FIGS. 2A and 2B show examples of combined emission spectra of the first light emitting element 11 and the phosphor 15.

In FIG. 2A, the first light emitting element 11 is a blue LED with 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 : a yellow phosphor comprising a ce ^3+, 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. 2A is about 481 nm. Further, 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 the emission spectrum of 15) is about 577 nm.

In this case, a light emitting element having a peak wavelength in a range R larger than 452 nm and smaller than 577 nm is used as the second light emitting element 12, and the peak wavelength deviates from 481 nm within 2 nm, that is, 479 nm or more and 483 nm or less. A light emitting element is preferably used as the second light emitting element 12. When a plurality of light emitting elements having different emission wavelengths are used as the second light emitting element 12, the peak wavelengths of all the light emitting elements are within the range R.

In FIG. 2B, the first light emitting element 11 is a purple LED having an emission wavelength of 405 nm, and the phosphor 15 is a blue phosphor composed of (Sr,Ca,Ba) ₁₀ (PO ₄ )Cl ₂ :Eu ^2+. , (Si,Al) ₆ (O,N) ₈ :Eu ^{2+ is} a green phosphor and CaAlSiN ₃ :Eu ^{2+ is} a red phosphor.

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 about 422 nm. Of the two peaks that form 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 402 nm, and the peak on the long wavelength side (the phosphor). The peak wavelength of the emission spectrum of 15) is about 454 nm.

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

The phosphor 15 may be included in both the first encapsulant 13 and the second encapsulant 14, but when included in the second encapsulant 14, the second light emitting element is included. Since the amount of absorption of the light emitted by 12 by the phosphor 15 increases, it becomes difficult to set the emission wavelength and emission intensity of the second light emitting element 12 to fill the deepest dip described above. Therefore, 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 it becomes difficult for light to pass from the second sealing material 14 to the first sealing material 13, the fluorescence emitted from the second light emitting element 12 is included in the first sealing material 13. The amount absorbed by the body 15 can be suppressed.

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

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 a face-up type LED chip in which the crystal layer faces upward, or a face-down type LED chip in which the crystal layer faces downward. May be. Further, it may be a light emitting element other than the LED chip such as a laser diode.

The first light emitting element 11 and the second light emitting element 12 are connected to a conductive member (not shown) such as 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, for example, a transparent resin such as a silicone resin or an epoxy resin.

Further, since power is supplied to the first light emitting element 11 and the second light emitting element 12 independently of each other, it is possible to arbitrarily adjust the light emission intensity of each. Therefore, the emission spectrum of the light emitting device 1 can be made closer to sunlight.

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

In the configuration example of the light emitting device of the present 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 sealing material. It is surrounded by the sealing material 13.

FIG. 3A shows the first light emitting element 11 and the second light emitting element 12 in the light emitting device 1 shown in FIG. 14 is a top view of the light emitting device 2 having a configuration in which the arrangement of 14 is reversed. FIG. FIG. 3B is a vertical cross-sectional view of the light emitting device 1 taken along the line BB of FIG. 3A.

In the configuration example of the light emitting device of the present 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 sealing material. It is surrounded by the sealing material 14. It should be noted that in addition to the configuration shown in FIG. 3, a ring-shaped sealing material made of the same material as the first sealing material 13 and sealing the first light emitting element 11 is used. A sealing material surrounding the stopper 14 may be added. Further, a ring-shaped sealing member made of the same material as the second sealing member 14 so as to surround the ring-shaped sealing member that seals the first light-emitting element 11, and seals the second light-emitting element 12 The material may be formed. The number of annular sealing materials that seal the first light emitting element 11 and the annular sealing material that seal the second light emitting element 12 that are alternately provided in this manner is not limited.

For example, when the second light emitting element 12 is composed of a plurality of light emitting elements having different wavelengths, a structure including a plurality of second light emitting elements 12 like the structure of the light emitting device 2 is adopted.

(Manufacturing process of light emitting device)
Hereinafter, an example of a manufacturing process of the light emitting device 1 will be described.

4A to 4C are vertical cross-sectional views showing a manufacturing process 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 placed on the substrate 10.

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

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

Next, as shown in FIG. 4C, 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 cross-sectional views showing a modified example 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 opposite to that of the manufacturing process shown in FIGS. 4A to 4C.

First, as shown in FIG. 6A, the first light emitting element 11 and the second light emitting element 12 are placed 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 having a pattern formed in advance is attached to the substrate 10 or by potting.

Next, as shown in FIG. 6C, an annular dam 16 is formed so as to surround the installation region of the first light emitting element 11. The dam 16 is made of, for example, 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, the resin containing the phosphor 15 is embedded in the 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 facilitates control of the shape of the first sealing material 13 formed by potting.

When 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 6A to 6D. The process for 12 may be reversed, and the process 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 transmitter for optical communication. A high-speed modulated signal for communication is sent to the second light emitting element 12 from, for example, an external control unit of the light emitting device 1, and the second light emitting element 12 emits light based on the signal to perform communication. In this case, the light emitting device 1 functions as an illumination and an optical transmitter of the transmission/reception system.

As the photodetector (reception unit) of this optical communication, for example, an Si photodiode or an image sensor such as a camera mounted as a standard on a smartphone is used. As a specific example, for example, the light emitting device 1 is a downlight used in a store, and transmits product information to a smartphone owned by a customer 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. 2B. Since it is in the front and back and in a region with low luminosity, even if the light intensity changes by using the second light emitting element 12, there is almost no effect such as flickering on the eyes, and communication is performed while suppressing the effect on the illumination function. Optical signals for can be superimposed.

FIG. 7A is a graph schematically showing the difference in the responsivity of the light emitting element, which is the LED chip, and the phosphor with respect to the frequency of the electric signal. As shown in FIG. 7A, the limit frequency at which the phosphor excited by the light emitted from the light emitting element can respond is lower than the limit frequency at which the light emitting element can respond to an electric 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 the difference in response speed between the light emitting element which is an LED chip and the phosphor. As shown in FIG. 7( b ), the waveform of the fluorescent substance is significantly distorted from the waveform of the electric signal as compared with the waveform of the light emitting element and becomes noise of the optical signal, which is not suitable for communication.

For this reason, the accuracy of communication decreases when the fluorescence of the phosphor is mixed with the light emitted from the second light-emitting element 12 for communication, and thus the second sealing material 14 that does not include the phosphor 15 is used for sealing. It is preferable to use the second light emitting element 12 for communication.

(Effects of the embodiment)
According to the above-described embodiment, by using the second light emitting element 12 for filling the deepest dip in the combined light emitting spectrum of the first light emitting element 11 and the phosphor 15, a light emitting spectrum close to sunlight is obtained. The light emitting device 1 can be provided. Also, the second light emitting element 12 can be used as a transmitter for optical communication.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the invention. Further, the constituent elements of the above-described embodiments 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. The above-described embodiment can be applied even when the depth is deep. 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.

Further, the above embodiment does not limit the invention according to the claims. Further, it should be noted that not all combinations of the features described in the embodiments are essential to the means for solving the problems of the invention.

1 Light-Emitting Device 10 Substrate 11 First Light-Emitting Element 12 Second Light-Emitting Element 13 First Sealing Resin 14 Second Sealing Resin 15 Phosphor

Claims (7)

A first light emitting element for emitting a first light emission spectrum in ultraviolet or ultraviolet region,
A blue phosphor that emits light of the second emission spectrum in the blue region ,
Light of the third emission spectrum having a peak wavelength between the peak wavelength of the purple or ultraviolet region and the peak wavelength of the blue region of the synthetic emission spectrum formed by the first emission spectrum and the second emission spectrum. A second light emitting element that emits
The light of the third emission spectrum the second light-emitting element is emitted is modulated by signal for optical communication, a light-emitting device. The deviation of the peak wavelength of the second light-emitting element from the wavelength of the bottom of the dip between the peak in the purple or ultraviolet region and the peak in the blue region in the combined emission spectrum 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 that seals the first light emitting element;
A second sealing material that seals the second light emitting element;
Further has
The phosphor is included in the first sealing material,
The light emitting device according to claim 1. 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 according to claim 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 4. The phosphor further including a green phosphor and a red phosphor,
The light emitting device according to any one of 請 Motomeko 1-6.

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