JP2001111114A - White led - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a white LED which can provide a high light at a low cost and be modulated at a high speed. SOLUTION: The white LED 1 comprises a UV LED light source 2, a plurality of red light emitting grains 4, a plurality of blue light emitting grains 5, and a plurality of green light emitting grains 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a white LED, and more particularly to a white LED capable of obtaining white light at low cost and capable of high-speed modulation.

[0002]

2. Description of the Related Art Conventionally, as a method of obtaining white light using an LED, a method of using a blue LED and a YAG-based phosphor to convert blue light emitted from a blue LED into white light,
A method of using a blue LED, a red LED, and a green LED, and mixing white light, red light, and green light emitted from the blue, red, and green LEDs to obtain white light has been put to practical use.

[0003]

However, the blue L
In the method using the ED and the YAG-based phosphor, white light can be obtained by using one LED, and the white light can be obtained at low cost because the configuration of the power supply circuit is simple. Although it has the advantage of being able to do so, there is a problem that the response speed of the phosphor is slow and high-speed modulation cannot be performed.

In the method using a blue LED, a red LED, and a green LED, the luminous efficiency is high, and the response speed is the same as the response speed of each of the blue LED, the red LED, and the green LED. It has the advantage of being able to modulate, but three LEDs
Each requires a power supply circuit, which not only has the problem of increased costs, but also causes degradation of each LED,
There was a problem of causing color shift.

Accordingly, an object of the present invention is to provide a white LED capable of obtaining white light at low cost and capable of high-speed modulation.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
This is achieved by an ultraviolet LED light source and a white LED comprising a plurality of red light emitting particles, a plurality of blue light emitting particles and a plurality of green light emitting particles.

According to the present invention, a plurality of red light emitting particles, a plurality of blue light emitting particles, and a plurality of green light emitting particles are excited by ultraviolet light emitted from an ultraviolet LED light source, and red light, red light, Blue light and green light are emitted and red light, blue light and green light are mixed to produce white light, so that the conventional red LE
Unlike the method using D, blue LED, and green LED, one LED can be used to generate white light, and only one power supply circuit is required, which is economical.

Further, according to the present invention, since no phosphor is used, white light can be turned on / off in the order of nsec, high-speed modulation is possible, and optical communication requiring high responsiveness is required. It can be used for such purposes.

Further, according to the present invention, a voltage is applied only to the ultraviolet LED light source, and no voltage is applied to the red light emitting particles, the blue light emitting particles or the green light emitting particles. As in the method using the LED and the green LED, it is possible to prevent the balance of the red light, the green light, and the blue light from being lost due to the deterioration of the LED, thereby preventing a color shift.

In a preferred embodiment of the present invention, a transparent layer is provided adjacent to the ultraviolet LED light source, and the plurality of red light emitting particles, the plurality of blue light emitting particles, and the plurality of green light emitting particles. Is provided in the transparent layer.

In a further preferred aspect of the present invention, the transparent layer is provided on the ultraviolet LED light source.

In a further preferred aspect of the present invention, the plurality of red light emitting particles, the plurality of blue light emitting particles, and the plurality of green light emitting particles are provided in a dispersed state in the transparent layer. I have.

[0013] In still another preferred embodiment of the present invention, the plurality of red light emitting particles, the plurality of blue light emitting particles, and the plurality of green light emitting particles are stacked in the transparent layer. .

In a further preferred aspect of the present invention, the transparent layer is constituted by a transparent resin layer.

[0015] In still another preferred embodiment of the present invention, the transparent layer is constituted by a transparent amorphous layer.

In a further preferred aspect of the present invention, the plurality of red light-emitting particles, the plurality of blue light-emitting particles, and the plurality of green light-emitting particles comprise the ultraviolet light L.
From the side closer to the ED light source, red light emitting particles, green light emitting particles, and blue light emitting particles are arranged in this order.

The size of the energy gap is in the order of blue light-emitting particles, blue light-emitting particles, and red light-emitting particles. The blue light-emitting particles most easily absorb ultraviolet light.
According to a further preferred embodiment of the present invention, red light-emitting particles, blue light-emitting particles and green light-emitting particles, from the near side of the ultraviolet LED light source, red light-emitting particles, green light-emitting particles and blue light-emitting particles It is arranged in order, therefore, because ultraviolet light emitted from the ultraviolet LED light source is prevented from being absorbed by the blue light emitting particles,
As desired, the red, blue and green light emitting particles can be excited by ultraviolet light to emit red, green and blue light respectively.

In a further preferred aspect of the present invention, the plurality of blue light-emitting particles and the plurality of green light-emitting particles each contain at least one element of Zn, Mg, Cd and Be; II-VI containing at least one element of, S, Te and O
It is formed of a semiconductor selected from the group consisting of a group III-V semiconductor containing a group semiconductor and at least one element of Ga, Al and In and containing at least one element of As, P and N.

In a further preferred aspect of the present invention, the plurality of red light emitting particles are formed of a semiconductor selected from the group consisting of a direct transition semiconductor and Si fine particles. Specific examples of the red light emitting particles include a III-V group semiconductor or a II-VI group semiconductor, for example, AlGaInP, AlGaAs, CdTe, and the like.

In a further preferred aspect of the present invention, the transparent resin layer is formed of a material selected from the group consisting of epoxy resin, polycarbonate, polystyrene and acrylic resin glass.

In a further preferred aspect of the present invention, the transparent amorphous layer is formed of tellurite-based glass or chalcogenide-based glass.

In the present invention, as the ultraviolet LED light source, for example, a ZnO-based II-VI group light source can be used.

[0023]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a schematic sectional view of a white LED according to a preferred embodiment of the present invention.

As shown in FIG. 1, the white LED 1
An ultraviolet LED light source 2 that emits ultraviolet light having a wavelength of 410 nm or less, and an epoxy-based transparent resin layer 3 formed on the ultraviolet LED light source 2 are provided.

In the transparent resin layer 3, a plurality of red light-emitting particles 4 that emit red light when excited, and a plurality of blue light-emitting particles 5 that emit blue light when excited. Thereby, a plurality of green light emitting particles 6 that emit green light are provided in a dispersed state. Here, the blue light emitting particles 5 and the green light emitting particles 6 include at least one element of Zn, Mg, Cd and Be, respectively, and include at least one element of Se, S, Te and O. Formed from a group II-VI semiconductor including at least one element of Ga, Al and In and a group III-V semiconductor including at least one element of As, P and N The red light emitting particles 4 are semiconductors selected from the group consisting of direct transition semiconductors and Si fine particles, such as AlGaInP, AlGaAs, and CdT.
It is formed of a III-V group semiconductor or II-VI group semiconductor such as e. The red light emitting particles 4, the blue light emitting particles 5, and the green light emitting particles 6 are arranged from the near side of the ultraviolet LED light source 2.
And blue light emitting particles 5 in this order.

The thus configured white LED 1 according to the preferred embodiment of the present invention emits white light as follows.

First, the ultraviolet LED light source 2 emits ultraviolet light 7 by injecting a current into the ultraviolet LED light source 2.

The ultraviolet light 7 emitted from the ultraviolet LED light source 2 enters the transparent resin layer 3 provided adjacent to the ultraviolet LED light source 2, and emits red light emitting particles 4 and green light emitting particles 6.
And the blue light emitting particles 5 are excited.

The red light emitting particles 4, the green light emitting particles 6, and the blue light emitting particles 5 are excited by ultraviolet rays 7 and emit red light, green light, and blue light, respectively.

Here, the magnitude of the energy gap is
The blue light emitting particles 5, the blue light emitting particles 5, and the red light emitting particles 4 are arranged in this order, and the blue light emitting particles 5 most easily absorb ultraviolet rays. The light-emitting particles 5 and the green light-emitting particles 6 are arranged in the order of the red light-emitting particles 4, the green light-emitting particles 6, and the blue light-emitting particles 5 from the near side of the ultraviolet LED light source 2. Since the emitted ultraviolet light 7 is prevented from being absorbed by the blue light emitting particles 5, the red light emitting particles 4, the blue light emitting particles 5, and the green light emitting particles 6 are excited by the ultraviolet light as desired. , Each emit red, green and blue light.

The red light, green light and blue light emitted from the red light emitting particles 4, the green light emitting particles 6, and the blue light emitting particles 5 are mixed in the transparent resin layer 3, and the white light 8 is radiated to the outside. Is done.

According to this embodiment, the ultraviolet LED light source 2
To emit red light-emitting particles 4, blue light-emitting particles 5, and green light-emitting particles 6 provided in the transparent resin layer 3 by the ultraviolet light 7.
Green light and blue light are emitted, and the emitted red light, green light and blue light are mixed in the transparent resin layer 3 to generate white light 8. Therefore, the conventional red LED,
Unlike the method using blue LED and green LED,
Since the white light 8 can be generated using one LED, only one power supply circuit is required, which is economical.

According to the present embodiment, since no phosphor is used, the white light is turned on and off in the order of nsec.
It can be turned off, high-speed modulation is possible, and it can be used for applications such as optical communication that requires high responsiveness.

Further, according to the present embodiment, the ultraviolet light LE
A voltage is applied only to the D light source 2, and the red light emitting particles 4,
Since no voltage is applied to the blue light emitting particles 5 or the green light emitting particles 6, the red light, the green light and the blue light are deteriorated as in the conventional method using a red LED, a blue LED and a green LED. Can be prevented from being out of balance and causing color misregistration.

FIG. 2 is a schematic sectional view of a white LED according to another embodiment of the present invention.

As shown in FIG. 2, in another embodiment of the present invention, the ultraviolet LED light source 2 includes a conductive substrate 10 made of SiC, and a GaN / GaInN / GaN provided on the conductive substrate 10. A plurality of red light emitting particles 4 comprising an excitation source 11 formed by a diode;
The blue light emitting particles 5 and the green light emitting particles 6
The ED light source 2 is stacked in this order and covered with a transparent resin layer 12 made of an epoxy resin.

According to this embodiment, it is not necessary to take out the p-electrode and the n-electrode from one side, which is advantageous in terms of configuration.

The present invention is not limited to the above-described embodiments and examples, and various modifications can be made within the scope of the invention described in the claims, which are also included in the scope of the present invention. It goes without saying that it is included.

For example, in the above embodiment, the transparent resin layers 2 and 12 are formed of epoxy resin, but the material forming the transparent resin layers 2 and 12 is not limited to epoxy resin. Other synthetic resins such as polycarbonate, polystyrene, acrylic resins, etc. can also be used.

In the above embodiment, the transparent resin layers 2 and 12 formed of epoxy resin are used. However, a transparent amorphous layer may be used instead of the transparent resin layers 2 and 12. The transparent amorphous layer can be formed of tellurite-based glass or chalcogenite-based glass.

Further, in the embodiment shown in FIG. 1, red light emitting particles 4, green light emitting particles 6 and blue light emitting particles 5 are
, Red light-emitting particles 4, green light-emitting particles 6, and blue light-emitting particles 5 are arranged in this order, and in the embodiment shown in FIG. The red light-emitting particles 4, the green light-emitting particles 6, and the blue light-emitting particles 5 are stacked in the order of the particles 4, the green light-emitting particles 6, and the blue light-emitting particles 5. 4. It is sufficient that the green light-emitting particles 6 and the blue light-emitting particles 5 are evenly excited, and the red light-emitting particles 4, the green light-emitting particles 6, and the blue light-emitting particles 5 in this order from the near side of the ultraviolet LED light source 2. It is not always necessary to arrange the red light emitting particles 4, the green light emitting particles 6, and the blue light emitting particles 5.

In the embodiment shown in FIG. 2, the excitation source 11 is provided on the conductive substrate 10,
Instead of the conductive substrate 10, the excitation source 11 may be provided on an insulating substrate formed of sapphire or the like. In this case, it is necessary to take out the p electrode and the n electrode from one side.

Furthermore, in the embodiment shown in FIG. 2, the conductive substrate 10 made of SiC is used, but the conductive substrate 10 can be made of n-type GaN.

Further, in the above embodiment, the transparent resin layers 3 and 12 are provided on the ultraviolet LED light source 2, but the ultraviolet rays emitted from the ultraviolet LED light source 2 are guided into the transparent resin layers 3 and 12. If possible, not only above,
It may be provided below or adjacent to the side.

[0046]

According to the present invention, white light can be obtained at low cost, and a white LED capable of high-speed modulation can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a white LED according to a preferred embodiment of the present invention.

FIG. 2 shows a white L according to another embodiment of the present invention.
It is a schematic sectional drawing of ED.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 White LED 2 UV LED light source 3 Transparent resin layer 4 Red light emitting particle 5 Blue light emitting particle 6 Green light emitting particle 7 Ultraviolet 8 White light 10 Conductive substrate 11 Excitation source 12 Transparent resin layer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5F041 AA02 AA14 AA31 CA04 CA33 CA34 CA36 CA40 CA41 CA46 DA44 DA46 DA47 DA58 DB01 EE25

Claims (12)

[Claims] 1. A white LED comprising an ultraviolet LED light source, a plurality of red light emitting particles, a plurality of blue light emitting particles, and a plurality of green light emitting particles. 2. A transparent layer is provided adjacent to the ultraviolet LED light source, and the plurality of red light emitting particles, the plurality of blue light emitting particles, and the plurality of green light emitting particles are provided in the transparent layer. The white LED according to claim 1, wherein: 3. The white light-emitting device according to claim 2, wherein the transparent layer is provided on the ultraviolet LED light source.
ED. 4. The light emitting device according to claim 2, wherein the plurality of red light emitting particles, the plurality of blue light emitting particles, and the plurality of green light emitting particles are provided in a dispersed state in the transparent layer. Or the white LED of 3. 5. The method according to claim 2, wherein the plurality of red light emitting particles, the plurality of blue light emitting particles, and the plurality of green light emitting particles are stacked in the transparent layer. The described white LED. 6. The white LED according to claim 2, wherein the transparent layer is formed of a transparent resin layer. 7. The method according to claim 2, wherein the transparent layer is constituted by a transparent amorphous layer.
A white LED according to the item. 8. The plurality of red light-emitting particles, the plurality of blue light-emitting particles, and the plurality of green light-emitting particles are arranged such that the red light-emitting particles, the green light-emitting particles, and the blue light from the side closer to the ultraviolet LED light source. The white LED according to any one of claims 1 to 7, wherein the white LED is arranged in the order of the light emitting particles. 9. The plurality of blue light-emitting particles and the plurality of green light-emitting particles each include at least one element of Zn, Mg, Cd, and Be;
II-VI semiconductor containing at least one element of S, Te and O and III containing at least one element of Ga, Al and In and containing at least one element of As, P and N The white LED according to any one of claims 1 to 8, wherein the white LED is formed of a semiconductor selected from the group consisting of -Group V semiconductors. 10. The semiconductor device according to claim 1, wherein the plurality of red light-emitting particles are formed of a semiconductor selected from the group consisting of a direct transition semiconductor and Si fine particles. White LED. 11. The white color according to claim 6, wherein said transparent resin layer is formed of a material selected from the group consisting of epoxy resin, polycarbonate, polystyrene and acrylic resin. LED. 12. The white LED according to claim 7, wherein the transparent amorphous layer is formed of tellurite-based glass or chalcogenide-based glass.