Patent Application
20170362501
The present invention relates to wavelength conversion members in which a phosphor is encapsulated within a glass tube.
In recent years, much development has been made of white light sources, for use in backlights of liquid crystal displays or other uses, in which an LED (light emitting diode) for emitting a blue light and a wavelength conversion member are used. In such a white light source, a white light is emitted which is a synthesized light of the blue light emitted from the LED and then transmitting through the wavelength conversion member and a yellow light emitted from the wavelength conversion member.
It is proposed to use, in a wavelength conversion member, a glass tube as a container for encapsulating a phosphor (Patent Literature 1). Furthermore, studies have recently been made on quantum dots as a phosphor. For example, it has been studied to form a wavelength conversion member by introducing into a glass tube a fluid in which quantum dots are dispersed in a resin.
The inventors found the problem that when an angular cylindrical glass tube is used as a glass tube for a wavelength conversion member, the color balance of light emitted from the wavelength conversion member deteriorates.
An object of the present invention is to provide a wavelength conversion member that can improve the color balance of emitted light.
The present invention is directed to a wavelength conversion member in which a phosphor is encapsulated within a glass tube, the glass tube including: a first flat-plate portion and a second flat-plate portion opposed to each other in a first direction perpendicular to a longitudinal direction of the glass tube; and a third flat-plate portion and a fourth flat-plate portion opposed to each other in a second direction perpendicular to both the longitudinal direction of the glass tube and the first direction, the first flat-plate portion being located on a light incident side of the glass tube through which excitation light for exciting the phosphor enters the glass tube, the second flat-plate portion being located on a light exit side of the glass tube through which fluorescence from the phosphor is emitted from the glass tube, at least one of a first corner connecting between the first flat-plate portion and the third flat-plate portion and a second corner connecting between the first flat-plate portion and the fourth flat-plate portion being chamfered.
In the present invention, both the first corner and the second corner are preferably chamfered.
A third corner connecting between the second flat-plate portion and the third flat-plate portion and a fourth corner connecting between the second flat-plate portion and the fourth flat-plate portion may be chamfered.
An example of the phosphor that can be cited is quantum dots. In this case, the quantum dots are preferably encapsulated as a dispersion in a resin within the glass tube.
The present invention enables to improve the color balance of light emitted from the wavelength conversion member.
Hereinafter, a description will be given of a preferred embodiment. However, the following embodiment is merely illustrative and the present invention is not intended to be limited to the following embodiment. Throughout the drawings, members having substantially the same functions may be referred to by the same reference characters.
As shown in
As shown in
Although no particular limitation is placed on the dimensions of the glass tube 10, for example, the distance between the inside wall surface of the first flat-plate portion 11 and the inside wall surface of the second flat-plate portion 12 and the distance between the inside wall surface of the third flat-plate portion 13 and the inside wall surface of the fourth flat-plate portion 14 can be each about 0.1 to about 5.0 mm. Furthermore, the thickness of the glass tube 10 can be, for example, about 0.05 to 2.5 mm. Moreover, the length of the glass tube 10 in the y direction can be about 2 to about 1000 mm.
No particular limitation is placed on the type of glass forming the glass tube 10. Examples that can be used as the glass tube 10 include silicate-based glasses, borate-based glasses, phosphate-based glasses, borosilicate-based glasses, and borophosphate-based glasses. Particularly preferred among them are silicate-based glasses and borosilicate-based glasses that have excellent transparency and can increase the light extraction efficiency.
For example, quantum dots can be used as the phosphor 2.
Examples of such quantum dots that can be cited include group II-VI compounds and group III-V compounds. Examples of such group II-VI compounds that can be cited include CdS, CdSe, CdTe, ZnS, ZnSe, and ZnTe. Examples of such group III-V compounds that can be cited include InP, GaN, GaAs, GaP, AlN, AlP, AlSb, InN, InAs, and InSb. At least one or a composite of two or more selected from the above compounds can be used as the quantum dots. Examples of such composites that can be cited include those having a core-shell structure, for example, a composite having a core-shell structure in which the surfaces of CdSe particles are coated with ZnS.
The particle diameter of the quantum dots is appropriately selected within a range of, for example, 100 nm or less, preferably 50 nm or less, particularly preferably 1 to 30 nm, more preferably 1 to 15 nm, or still more preferably 1.5 to 12 nm.
The quantum dots are preferably introduced as a dispersion in a resin into the glass tube 10. Examples of such resins to be used include ultraviolet curable resins and thermosetting resins. Specifically, for example, epoxy-based curable resins, acrylic ultraviolet curable resins, and silicone-based curable resins can be used. These resins are preferred because they are resins having fluidity during the introduction.
The phosphor 2 used is not limited to quantum dots and, for example, particles of an inorganic phosphor, such as oxide phosphor, nitride phosphor, oxynitride phosphor, chloride phosphor, oxychloride phosphor, sulfide phosphor, oxysulfide phosphor, halide phosphor, chalcogenide phosphor, aluminate phosphor, halophosphoric acid chloride phosphor, or garnet-based compound phosphor, may be used.
In the wavelength conversion member 1 according to this embodiment, as shown in
In this embodiment, the third corner 23 and the fourth corner 24 both located on the light exit side are also chamfered. However, the third corner 23 and the fourth corner 24 both located on the light exit side do not always have to be chamfered. By chamfering the third flat-plate portion 23 and the fourth flat-plate portion 24, any flat-plate portion of the glass tube 10 can be disposed on the light incident side to serve as the first flat-plate portion 11, so that the glass tube 10 becomes easy to handle.
Furthermore, although in this embodiment both the first corner 21 and the second corner 22 are chamfered, the present invention is not limited to this and it is sufficient that at least one of the first corner 21 and the second corner 22 is chamfered.
Although in this embodiment a so-called C-chamfering is made as the chamfering, the present invention is not limited to this. Any chamfering will work if it enables at least part of excitation light 3 entering the third flat-plate portion 13 and the fourth flat-plate portion 14 to be refracted by the incident surface to enter the phosphor 2. For example, a so-called R-chamfering may be made which forms a curved surface on the corner.
In the case of chamfering resulting in the formation of an inclined surface, the angle of inclination of the inclined surface is preferably in a range of 30 to 60° to the x direction and more preferably in a range of 40 to 50° to the x direction. By employing such a range, excitation light 3 incident on the third flat-plate portion 13 and the fourth flat-plate portion 14 becomes likely to enter the phosphor 2.
No particular limitation is placed on the method for producing the wavelength conversion member 1 according to this embodiment. For example, the wavelength conversion member can be produced by the following method. A glass tube 10 is prepared in which an end 10a is sealed and an end 10b is open. A phosphor 2 is introduced though the open end 10b into the glass tube 10, thus filling the inside of the glass tube 10 with the phosphor 2. Specifically, the end 10b of the glass tube 10 is put into a phosphor 2 in fluid state while the inside of the glass tube 11 is kept under reduced pressure, so that the phosphor 2 can be introduced into the glass tube 10. In this embodiment, since quantum dots dispersed in a resin are used as the phosphor 2, the resin during introduction of the phosphor 2 is uncured and therefore has fluidity. After the phosphor 2 is introduced into the glass tube 10, the resin around the phosphor 2 is cured by ultraviolet irradiation or other means. Thereafter, by fusing the glass or using another member, the open end 10b is sealed.
1, 31 . . . wavelength conversion member
2 . . . phosphor
3 . . . excitation light
4 . . . fluorescence
10 . . . glass tube
10
a, 10b . . . end
11 . . . first flat-plate portion
12 . . . second flat-plate portion
13 . . . third flat-plate portion
14 . . . fourth flat-plate portion
15, 16, 17, 18 . . . inclined surface
21 . . . first corner
22 . . . second corner
23 . . . third corner
24 . . . fourth corner
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-080613 | Apr 2015 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2016/054253 | 2/15/2016 | WO | 00 |
