JP2009032683A - Light emitting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting apparatus which can efficiently generate white color light of high luminance. <P>SOLUTION: An emitter layer 16 is formed by using a blue color emitter and a yellow color emitter of a high light emitting efficiency to generate a white color light. At this time, by exposing blue color emitter particles 17 and yellow color emitter particles 81 on a surface of the emitter layer 16, electrons are directly irradiated both of the emitter particles 17, 18 and an excellent electron exciting can be realized. Moreover, by using a YAG or the like, as a yellow color emitter, which emits a yellow color not only by the electron exciting but also by an optical exciting by a blue light color, the blue light color can contribute for emitting the yellow light color even if a part of the blue color light emitted by the blue color emitter particles 18 is shielded by the yellow color emitter particles 18 when passing through the emitter layer 16, and an energy loss can be reduced to generate the white color light efficiently. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light emitting device that generates white light by exciting and emitting a light emitter (phosphor) with electrons emitted from a cold cathode electron emission source.

  In recent years, in comparison with conventional light emitting devices such as incandescent bulbs and fluorescent lamps, electrons emitted from a cold cathode electron emission source in a vacuum are caused to collide with a light emitter (phosphor) at high speed, thereby causing the light emitter to emit light. Cold cathode field emission type light emitting devices have been developed, and are expected to be used as field emission lamps (FEL) and field emission display devices (FED).

  Among these light emitting devices, in the FED manufacturing process, various microprocesses of micron order according to the pixel size are generally used. For example, in the FED manufacturing process, a cathode (cathode electrode) is formed on an insulating substrate such as glass or ceramics by a well-known microprocess used for semiconductor chips such as sputtering and CVD. Further, a columnar molten material was formed directly on the insulating substrate or connected to a wiring layer formed on the surface of the insulating substrate, and a plurality of openings having a diameter of 10 to 100 μm were formed in the columnar molten material. A gate electrode is formed by fixing a thin metal plate having a thickness of 30 to 60 μm.

  On the other hand, in FEL specialized for lamp light sources and the like, it is not necessary to perform micron-order microfabrication such as FED on the cathode electrode and the like, and the diameter of the opening formed in the gate electrode is also small. A relatively large diameter on the order of millimeters is sufficient (for example, see Patent Document 1).

Therefore, in the manufacture of FEL, it is possible to eliminate the micro process that requires a large amount of equipment cost, and to manufacture each functional component by combining the components that can be mass-produced only by the process in the atmosphere. Can expect down. For example, the cathode electrode and the gate electrode have a thickness of 0. It is conceivable that the FEL is manufactured at low cost by constituting individual functional parts each having a metal plate of about several mm as a base material and assembling them in a vacuum vessel.
JP 2006-339012 A

  By the way, this type of FEL is required to emit white light in many cases such as when used as a light source for various illuminations.

  However, many light emitters that emit white light by ultraviolet rays, such as light emitters that are widely used in fluorescent tubes, have been developed to emit light with high luminance, but white light is excited by electrons. As for the illuminant, a substance that emits light with sufficiently high luminance has not been developed.

  Therefore, in FEL, for example, when white light is excited by providing a light emitter that excites white light on the anode electrode, energy loss in the light emitter layer increases, and high-intensity white light is efficiently generated. May be difficult.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a light-emitting device capable of efficiently generating high-intensity white light.

  The present invention provides a cathode layer having a cold cathode electron emission source formed on a surface thereof, and a phosphor layer in which a plurality of types of phosphors that emit excitation light by electrons emitted from the cold cathode electron emission source are mixed. An anode electrode formed on a surface facing the electrode, and a vacuum vessel, wherein each type of light emitter has a relationship of generating white light by mixing light emission, and the surface of the light emitter layer Are distributed so as to be directly exposed to the field-emitted electrons, and at least one of the light emitters has a characteristic of being excited and emitted by light from other types of the light emitters. It is characterized by.

  According to the light-emitting device of the present invention, high-intensity white light can be generated efficiently.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings relate to an embodiment of the present invention, FIG. 1 is a basic configuration diagram of a light emitting device, FIG. 2 is a schematic diagram showing an enlarged luminescent layer, and FIG. 3 is an illustration of excited luminescence of a blue luminescent material and a yellow luminescent material. FIG. 4 is a diagram showing a luminance distribution of light emitted from a single blue light emitter, a single yellow light emitter, and a mixture of these light emitter layers, and FIG. 5 is a blue light emitter and a yellow light emitter in the light emitter layer. It is a graph which shows the relationship between the weight ratio and brightness | luminance.

  As shown in FIG. 1, a light emitting device 1 in the present embodiment is a light emitting device used as, for example, a planar field emission type white illumination lamp, and a vacuum container in which glass substrates 2 and 3 are arranged to face each other at a predetermined interval. 4 has a basic configuration in which a cathode electrode 5, a gate electrode 10, and an anode electrode 15 are arranged in order from the base surface side to the light projecting surface side.

  The cathode electrode 5 is made of a conductive material formed on the glass substrate 2 serving as the base surface. For example, a metal such as aluminum or nickel is deposited by vapor deposition or sputtering, or a silver paste material is applied and dried. It is formed by firing. On the surface of the cathode electrode 5, emitter materials such as carbon nanotubes, carbon nanowalls, spint-type microcones, and metal oxide whiskers are applied in a film shape to form a cold cathode electron emission source 6.

  In this embodiment, the cold cathode electron emission source 6 is patterned for each predetermined region, and a cathode mask 7 covering the cathode electrode 5 is arranged around the patterned region (electron emission region).

  The gate electrode 10 is composed of a flat plate member having an opening 11 through which electrons emitted from the cold cathode electron emission source 6 pass. Specifically, the gate electrode 10 has a simple mechanical structure in which a plurality of openings 11 corresponding to the pattern region of the cold cathode electron emission source 6 are formed on a conductive metal plate such as a nickel material, a stainless material, or an amber material. The main part is formed by processing or the like. The opening 11 of the gate electrode 10 is formed as a circular hole formed, for example, the same as or slightly larger than the pattern region of the cold cathode electron emission source 6 formed in a land shape. As a result, almost all electrons emitted from the cold cathode electron emission source 6 can be passed to be effective electrons contributing to light emission, reducing power loss at the gate electrode 10 and realizing a lossless gate. It is possible.

  The anode electrode 15 is made of a transparent conductive film (for example, ITO film) disposed on the back side of the glass substrate 3 serving as a light projecting surface, and cold cathode electron emission is performed on the surface facing the gate electrode 10 (cathode electrode 5). A light emitter layer 16 is formed that is excited and emitted by electrons emitted from the source 6.

  The light emitter layer 16 is formed by mixing a plurality of types of light emitters (phosphors) having different wavelength bands of light that is excited to emit light, and generates white light by mixing light from these light emitters. In the present embodiment, the light emitter layer 16 includes, for example, a blue light emitter (first light emitter) that excites blue light and a yellow light emitter (first light emitter) that emits yellow light that is complementary to the blue light. 2 light emitters). In this case, for example, a zinc sulfide (ZnS) -based blue light emitter to which an activator of several ppm is added is preferably used as the blue light emitter. As described above, blue light mainly having a wavelength band of 400 to 600 nm is emitted with high luminous efficiency by excitation light emission by electrons. On the other hand, an yttrium-aluminum-garnet (YAG) yellow illuminant is preferably used as the yellow illuminant. Primarily emits yellow light having a wavelength band of 450 to 650 nm with high luminous efficiency. Furthermore, the YAG-based yellow light emitter used in the present embodiment has a characteristic of exciting and emitting yellow light even with blue light.

  As shown in FIG. 2, the luminescent layer 16 is specifically formed by mixing blue luminescent particles 17 and yellow luminescent particles 18. Various types of phosphor particles 17 and 18 are exposed and distributed on the surface of the phosphor layer 16, and the exposed phosphor particles 17 and 18 are cold cathode electrons in the vacuum vessel 4. Each of the electrons emitted from the emission source 6 is directly exposed.

  Such a phosphor layer 16 is formed by, for example, sequentially applying a dispersion liquid containing yellow phosphor particles and a dispersion liquid containing blue phosphor particles on the anode electrode 15 by screen printing or the like, and performing each heat treatment step through each dispersion liquid. It is formed by removing the solvent. At that time, by setting the concentration and coating amount of the dispersion containing each phosphor particle, conditions of the heat treatment step, etc. to appropriate values, the phosphor particles 17 and 18 are arranged on the anode electrode 15 at a predetermined density. Both phosphor particles 17 and 18 can be distributed so as to be exposed on the surface of the phosphor layer 16. Specifically, for example, in the case where a dispersion liquid containing yellow luminescent particles and a dispersion liquid containing blue luminescent particles are sequentially applied on the anode electrode 15, in particular, a solvent occupying the dispersion containing blue luminescent particles. By distributing the blue phosphor particles 17 at a predetermined sparse density, for example, by increasing the ratio of the yellow phosphor particles, some of the yellow phosphor particles from the gaps of the blue phosphor particles 17 on the surface of the phosphor layer 16. 18 can be exposed.

  For example, as shown in FIG. 3, the blue phosphor particles 17 are excited by being directly exposed to the electrons emitted from the cold cathode electron emission source 6 and emit blue light Be. Similarly, the yellow phosphor particles 18 are excited by being directly exposed to the electrons emitted from the cold cathode electron emission source 6 and emit yellow light Ye. Further, the yellow luminescent particles 18 are photoexcited by the blue light Be emitted from the neighboring blue luminescent particles 17 and emit yellow light Yl. The blue light Be and the yellow light Ye, Yl are mixed on the light projecting surface side of the glass substrate 3, whereby the light emitting device 1 efficiently generates the high-intensity white light W.

  That is, by exposing the blue luminescent particles 17 and the yellow luminescent particles 18 on the surface of the luminescent layer 16, each of the luminescent particles 17, 18 can be directly exposed to electrons, for example, blue luminescent particles. Compared with the case where a light emitter layer is formed by superimposing 17 and yellow light emitter particles 18 in separate layers, both blue light and yellow light can be efficiently emitted by electronic excitation. Further, at least a part of each of the phosphor particles 17 and 18 may not be completely exposed on the surface of the phosphor layer, and other substances such as glass and silica may be interposed between the surface of the phosphor layer and each particle. Even if the substance is present, if the substance has a property of transmitting field-emitted electrons, the phosphor particles 17 and 18 are directly exposed to electrons, and the same effect can be obtained. .

  In addition, since the yellow phosphor particles 18 of the present embodiment have the property of being excited and emitted not only by electrons but also by blue light, yellow light is emitted when a part of the electronically excited blue light passes through the phosphor layer 16. Even when blocked by the luminescent particles 18, the blue light can be used effectively to improve the luminance of yellow light.

That is, if the blue light emitter monochromatic luminance by electronic excitation is Lb, the yellow light emitter monochromatic luminance by electronic excitation is Ly, and the mixing ratio of the blue light emitter and the yellow light emitter is A: B (A + B = 1), In addition, the luminance Lw of the white light W generated by the mixed light of the blue light and the yellow light electronically excited by each light emitter is a weighted average of the respective luminances,
Lw = A × Lb + B × Ly. In addition to these, in the phosphor layer 16 of the present embodiment, the yellow phosphor particles 18 are excited to emit light even by blue light, and accordingly, the brightness of white light can be improved. For example, as indicated by a solid line in FIG. 5, the luminance of white light obtained by the light emitter layer 16 of the present embodiment is higher than the weighted average value of each luminance of blue light and yellow light by electronic excitation.

  Here, the mixing ratio of the blue luminescent particles 17 and the yellow luminescent particles 18 in the luminescent layer 16 is set in consideration of the luminance of yellow light photoexcited by blue light. In this case, the influence of yellow light photoexcited by blue light on the luminance Lw of white light varies depending on the weight ratio of the blue light emitter and the yellow light emitter. That is, the luminance of the yellow light Yl emitted from the yellow light emitter per unit amount by light excitation increases as the ratio of the blue light emitter increases. On the other hand, when the ratio of the blue light emitters exceeds a predetermined value, the absolute amount of the yellow light emitters decreases, so the ratio of the luminance of the yellow light Yl due to photoexcitation to the entire luminance Lw of the white light decreases. Considering the influence of the yellow light Yl due to such photoexcitation, for example, as shown in FIG. It is possible to obtain suitable white light.

  According to such an embodiment, by forming the light emitter layer 16 using a blue light emitter and a yellow light emitter with high light emission efficiency, white light can be emitted without using a white light emitter with low light emission efficiency. Can be generated. At that time, by distributing the blue phosphor particles 17 and the yellow phosphor particles 18 so as to be exposed on the surface of the phosphor layer 16, electrons are directly irradiated to any of the phosphor particles 17 and 18. And efficient electronic excitation can be realized. In addition, by using YAG or the like that emits yellow light not only by electronic excitation but also by light excitation by blue light as a yellow light emitter, a part of the blue light emitted from the blue light emitter particles 17 passes through the light emitter layer 16. Even when the light is blocked by the yellow luminescent particles 18, the blue light can contribute to the emission of yellow light, and the white light can be efficiently generated with reduced energy loss.

  In the above-described embodiment, an example in which the light emitter layer is formed using two kinds of light emitters of a blue light emitter and a yellow light emitter has been described, but the present invention is not limited thereto, It is also possible to form a light emitter layer by mixing light emitters of two or more kinds of other emission colors.

Basic configuration diagram of light emitting device Schematic diagram showing enlarged luminescent layer Explanatory drawing about excitation light emission of blue light emitter and yellow light emitter A chart showing the luminance distribution of light emitted by each of the blue light emitter, the yellow light emitter, and a mixture of the light emitter layers. Chart showing the relationship between the weight ratio of the blue and yellow emitters and the luminance in the phosphor layer

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Light-emitting device 2, 3 ... Glass substrate 4 ... Vacuum container 5 ... Cathode electrode 6 ... Cold-cathode electron emission source 7 ... Cathode mask 10 ... Gate electrode 11 ... Opening part 15 ... Anode electrode 16 ... Light-emitting body layer 17 ... Blue light emission Body particles 18 ... Yellow phosphor particles

Claims (4)

A cathode electrode having a cold cathode electron emission source formed on the surface;
An anode electrode in which a phosphor layer in which a plurality of types of phosphors excited by light emitted from a field emission electron from the cold cathode electron emission source are mixed is formed on a surface facing the cathode electrode, and is provided in a vacuum container. ,
Each type of illuminant has a relationship of generating white light by mixing of each luminescence, and is distributed on the surface of the illuminant layer so that each is directly exposed to the field-emitted electrons. ,
At least one of the light emitters has a characteristic of being excited and emitted by light from other types of the light emitters. A cathode electrode having a cold cathode electron emission source formed on the surface;
An anode electrode in which a phosphor layer in which a plurality of types of phosphors excited by light emitted from a field emission electron from the cold cathode electron emission source are mixed is formed on a surface facing the cathode electrode, and is provided in a vacuum container. ,
Each type of illuminant has a relationship of generating white light by mixing light emission, and each is exposed on the surface of the illuminant layer,
At least one of the light emitters has a characteristic of being excited and emitted by light from other types of the light emitters. The luminous body layer is formed by mixing a first luminous body that excites blue light and a second luminous body that emits yellow light.
3. The light emitting device according to claim 1, wherein the second light emitter emits yellow light by blue light excited by the first light emitter. 4.   4. The light emitting device according to claim 3, wherein a weight ratio between the first light emitter and the second light emitter is set in a range of 3: 1 to 1: 1. 5.

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