JP3117790U - Surface light source device - Google Patents

Abstract

A planar light source device capable of improving the extraction efficiency of light wavelength-converted by a phosphor and increasing the amount and surface area of the phosphor and capable of emitting multicolor light.
A light guide plate 12 made of a translucent material whose surface is formed with a light exit surface 12b, and an LED 14 disposed in the vicinity of one end surface 12a of the light guide plate 12, and the light exit surface 12b of the light guide plate 12 is provided. In addition, the sheet-like first non-woven fabric 18R formed by carrying a phosphor 16R for red light emission that radiates the light emitted from the LED 14 into red visible light, and converts the wavelength into green visible light for radiation. Sheet-like second non-woven fabric 18G carrying a green-emitting phosphor 16G, and a third sheet-like non-woven fabric carrying a blue-emitting phosphor 16B that radiates by converting the wavelength to blue visible light. A non-woven fabric 18B is disposed, and the outer surface of the LED 14, the back surface 12c of the light guide plate 12, and the end surface other than the one end surface 12a of the light guide plate 12 on which the LED 14 is disposed are covered with a light reflecting member 24 made of aluminum or the like. A planar light source device 10.
[Selection] Figure 1

Description

  The present invention relates to a planar light source device capable of emitting multicolor light, which can be suitably used for a backlight of a liquid crystal display panel, a light source of operation switches, and the like.

FIG. 9 shows an example of a conventional planar light source device. The planar light source device 70 is disposed along a light guide plate 72 made of a translucent material and one end surface 72 a of the light guide plate 72. A light emitting diode (LED) 74 is provided as a light source.
Further, the outer side of the LED 74, the back surface of the light guide plate 72, and the end surface other than the one end surface 72a of the light guide plate 72 on which the LED 74 is disposed are covered with a light reflecting member 76.
The surface of the light guide plate 72 is formed as a light exit surface 72b. On the light exit surface 72b, a red light emitting phosphor 78R that emits the light emitted from the LED 74 by converting the wavelength into red visible light. A green light emitting phosphor 78G that radiates by converting the wavelength to green visible light and a blue light emitting phosphor 78B that converts the wavelength to blue visible light and radiates are coated in a film form. These film-like phosphors 78R, 78G, and 78B are formed by mixing and firing the phosphors 78R, 78G, and 78B in a binder, respectively.

  In the planar light source device 70, the light emitted from the LED 74 enters the light guide plate 72 from one end surface 72a of the light guide plate 72, and then exits the light emitting surface 72b substantially uniformly to emit the phosphor 78R. By irradiating 78G and 78B, visible light of three colors of red visible light, green visible light and blue visible light is emitted to the outside.

By the way, in the above conventional planar light source device 70, the wavelength-converted light by the phosphors 78R, 78G, 78B becomes “transmitted light” that is transmitted through the film-like 78R, 78G, 78B. A portion of the converted light is absorbed (self-absorbed) by the phosphors 78R, 78G, and 78B until it passes through the film-like phosphors 78R, 78G, and 78B and is emitted to the outside. The removal efficiency of was not good.
The luminance of light emitted from the phosphors 78R, 78G, 78B is generally proportional to the amount and surface area of the phosphors 78R, 78G, 78B. In this case, since the phosphors 78R, 78G, and 78B are deposited in a film shape on the light output surface 72b of the light guide plate 72, a sufficient amount and surface area of the phosphors 78R, 78G, and 78B can be secured. There wasn't.

  The present invention has been devised in view of the above-described conventional problems, and the object of the present invention is to improve the extraction efficiency of light wavelength-converted by the phosphor, and the amount of the phosphor and An object is to realize a planar light source device capable of increasing the surface area and capable of emitting multicolor light.

  In order to achieve the above object, a first planar light source device according to the present invention includes a light source that emits light having a wavelength that excites a phosphor, and a light guide plate whose surface is a light exit surface. A plurality of fiber assemblies are arranged on the light exit surface of the light guide plate, and each fiber assembly emits visible light having a light emission color different from the emission color of the phosphor carried by the other fiber assembly. It is characterized by carrying a phosphor.

In addition, a second planar light source device according to the present invention includes a light source that emits light having a wavelength that excites a phosphor, and a light guide plate whose surface is a light output surface, and a plurality of light sources on the back surface of the light guide plate. In addition, each fiber assembly is loaded with a phosphor that emits visible light of an emission color different from the emission color of the phosphor carried by the other fiber assembly. It is characterized by.
In this case, you may set the thickness of a light-guide plate to the thickness radiated | emitted from a light-emitting surface, without the visible light radiated | emitted from the aggregate | assembly of each fiber mixing.

  The aggregate of the fibers is preferably a non-woven fabric. In this case, the phosphor is supported on the fibers constituting the non-woven fabric.

In the first planar light source device and the second planar light source device according to the present invention, an assembly of a plurality of fibers carrying phosphors having different emission colors is prepared, and the assembly of these fibers is prepared. A planar light source device capable of emitting multicolor light can be easily obtained simply by arranging the body on the light exit surface of the light guide plate or the back surface of the light guide plate.
In addition, the first planar light source device and the second planar light source device of the present invention support the phosphor three-dimensionally by supporting the phosphor on the fiber assembly. As a result, The light whose wavelength is converted by the phosphor can be extracted as reflected light reflected by the phosphor. For this reason, the light extraction efficiency is improved as compared with the conventional planar light source device 70 in which the light whose wavelength is converted by the phosphors 78R, 78G, and 78B is extracted as transmitted light.
Furthermore, since the first planar light source device and the second planar light source device of the present invention have the phosphors supported on the assembly of fibers having a large surface area per unit volume, the conventional planar light source Compared with the case where the phosphors 78R, 78G, and 78B are deposited on the light exit surface 72b of the light guide plate 72 as in the device 70, the amount and surface area of the phosphor can be increased.

  When a non-woven fabric formed by entanglement of a large number of fibers is used as an assembly of the above fibers, and the phosphor is supported on the fibers constituting the non-woven fabric, the surface area of the fibers per unit volume is extremely large Therefore, as in the case of the conventional planar light source device 70, the amount and surface area of the phosphor are dramatically increased as compared with the case where the phosphors 78R, 78G, and 78B are deposited on the light exit surface 72b of the light guide plate 72 in the form of a film. Can be increased.

Hereinafter, an embodiment of a planar light source device according to the present invention will be described with reference to the drawings.
1 and 2 show a first planar light source device 10 according to the present invention. This first planar light source device 10 is made of a light-transmitting material such as acrylic resin, glass, polycarbonate resin, or the like. And a plurality of LEDs 14 as light sources arranged in the vicinity of one end surface 12a of the light guide plate 12. The LED 14 emits light such as ultraviolet light and visible light having a wavelength for exciting a phosphor to be described later, and is not limited to the LED 14, and a cold cathode tube or the like can also be used.

  The surface of the light guide plate 12 is a light exit surface 12b. Further, on the light exit surface 12b of the light guide plate 12, a sheet as a fiber aggregate formed by carrying a phosphor 16R for red light emission that radiates the light emitted from the LED 14 by converting the wavelength of the light into red visible light. First nonwoven fabric 18R in the form of a sheet, second nonwoven fabric 18G in the form of a sheet carrying green phosphor 16G for wavelength conversion to green visible light, and blue color to be emitted after wavelength conversion to blue visible light A sheet-like third nonwoven fabric 18B formed by carrying a phosphor 16B for light emission is disposed.

The nonwoven fabrics 18R, 18G, and 18B are formed by three-dimensionally intertwining many fibers 20 as shown in FIGS. 3 and 4 showing the second nonwoven fabric 18G. 5 (see FIG. 5) is formed, and a large number of fibers 20 are intertwined with each other, so that the surface area of the fibers 20 per unit volume is extremely large.
The phosphors 16R, 16G, and 16B are attached to and supported on the surface of the fibers 20 constituting the nonwoven fabrics 18R, 18G, and 18B. As shown in FIG. A large number of particles are deposited.
Incidentally, the fiber density of the fibers 20 constituting the nonwoven fabrics 18R, 18G, 18B, the thickness of the nonwoven fabrics 18R, 18G, 18B, the basis weight, etc. are appropriately adjusted, so that the total of the fibers 20 constituting the nonwoven fabrics 18R, 18G, 18B are adjusted. The surface area can be arbitrarily increased or decreased.

The fiber 20 is a resin fiber such as nylon, polyester, acrylic, polypropylene, polyvinyl chloride or fluororesin, a cellulosic chemical fiber such as rayon, a metal fiber such as glass fiber, alumina or boron, or a short fiber such as natural fiber. The diameter is 1 to 20 μm, and the length is about 0.5 to 20 mm.
Of course, it is also possible to use fibers 20 made of long fibers having a length of about 50 to 100 mm.

When the phosphors 16R, 16G, and 16B are irradiated with light such as ultraviolet rays and blue visible light, the phosphors 16R, 16G, and 16B convert the wavelength of the light into light such as visible light having a predetermined wavelength. Can be used.
As a phosphor 16R for red light emission that converts light such as ultraviolet rays into red visible light, M ₂ O ₂ S: Eu (M is any one of La, Gd, and Y), 0.5MgF ₂ .3.5MgO. _{GeO 2: Mn, 2MgO · 2LiO} 2 · Sb 2 O 3: Mn, Y (P, V) O 4: Eu, YVO 4: Eu, (SrMg) 3 (PO 4): Sn, Y 2 O 3: Eu , CaSiO ₃ : Pb, Mn and the like.
Further, the phosphor 16G for green emission for converting light such as ultraviolet rays to green visible _{light, BaMg 2 Al 16 O 27:} Eu, Mn, Zn 2 SiO 4: Mn, (Ce, Tb, Mn) MgAl 11 O ₁₉ , LaPO ₄ : Ce, Tb, (Ce, Tb) MgAl ₁₁ O ₁₉ , Y ₂ SiO ₅ : Ce, Tb, ZnS: Cu, Al, ZnS: Cu, Au, Al, (Zn, Cd) S: Cu , Al, SrAl ₂ O ₄ : Eu, SrAl ₂ O ₄ : Eu, Dy, Sr ₄ Al ₁₄ O ₂₅ : Eu, Dy, Y ₃ Al ₅ O ₁₂ : Tb, Y ₃ (Al, Ga) ₅ O ₁₂ : There are Tb, Y ₃ Al ₅ O ₁₂ : Ce, Y ₃ (Al, Ga) ₅ O ₁₂ : Ce, and the like.
Further, as a phosphor 16B for blue light emission that converts light such as ultraviolet rays into blue visible light, (SrCaBa) ₅ (PO ₄ ) ₃ Cl: Eu, BaMg ₂ Al ₁₆ O ₂₇ : Eu, (SrMg) ₂ P ₂ O ₇ : Eu, Sr ₂ P ₂ O ₇ : Eu, Sr ₂ P ₂ O ₇ : Sn, Sr ₅ (PO ₄ ) ₃ Cl: Eu, BaMg ₂ Al ₁₆ O ₂₇ : Eu, CaWO ₄ , CaWO ₄ : Pb , ZnS: Ag, Cl, ZnS : Ag, Al, (Sr, Ca, Mg) 10 (PO 4) 6 Cl 2: there is Eu and the like.
The phosphors 16R, 16G, and 16B include organic and inorganic fluorescent dyes and organic and inorganic fluorescent pigments.

  The outer surface of the LED 14, the back surface 12c of the light guide plate 12, and the end surface other than the one end surface 12a of the light guide plate 12 on which the LED 14 is disposed are covered with a light reflecting member 24 made of aluminum or the like.

In the first planar light source device 10, after the light emitted from the LED 14 enters the light guide plate 12 from the one end surface 12a of the light guide plate 12, it is emitted substantially uniformly from the light output surface 12b. The phosphor 16R for red light emission carried on one nonwoven fabric 18R, the phosphor 16G for green light emission carried on the second nonwoven fabric 18G, and the phosphor 16B for blue light emission carried on the third nonwoven fabric 18B. By irradiating, visible light of three colors of red visible light, green visible light and blue visible light is emitted.
Of the light radiated from the LED 14, the light that did not go to the one end surface 12 a side of the light guide plate 12 is reflected by the light reflecting member 24 that covers the outer side of the LED 14, and the one end surface 12 a side of the light guide plate 12. Can lead to. Further, the light reflecting member 24 can prevent light from escaping from the end surface other than the one end surface 12a of the light guide plate 12. Furthermore, the light emitted from the back surface 12c of the light guide plate 12 can be reflected by the light reflecting member 24 and guided to the light exit surface 12b side.

Thus, in the first planar light source device 10, a plurality of nonwoven fabrics 18R, 18G, and 18B carrying phosphors 16R, 16G, and 16B having different emission colors are prepared, and these nonwoven fabrics 18R are prepared. , 18G, and 18B can be easily obtained by simply arranging the light emitting surface 12b of the light guide plate 12 by adhering them to the surface light source device capable of emitting multicolor light.
Further, in the first planar light source device 10 of the present invention, three nonwoven fabrics 18R, 18G, and 18B are arranged on the light exit surface 12b of the light guide plate 12, and the fibers constituting the nonwoven fabrics 18R, 18G, and 18B are arranged. Since the phosphors 16R, 16G, and 16B are carried on the surface of the phosphor 20, the phosphors 16R, 16G, and 16B are three-dimensionally supported. As a result, the wavelengths of the phosphors 16R, 16G, and 16B are converted. Light can be extracted as reflected light reflected by the phosphors 16R, 16G, and 16B. For this reason, the light extraction efficiency is improved as compared with the conventional planar light source device 70 in which light converted in wavelength by the phosphors 78R, 78G, and 78B is extracted as transmitted light.
Further, the first planar light source device 10 of the present invention supports the phosphors 16R, 16G, and 16B on the surface of the fibers 20 constituting the nonwoven fabrics 18R, 18G, and 18B having a very large surface area of the fibers 20 per unit volume. Therefore, the amount of the phosphors 16R, 16G, and 16B is larger than that in the case where the phosphors 78R, 78G, and 78B are deposited on the light output surface 72b of the light guide plate 72 as in the conventional planar light source device 70. And the surface area can be dramatically increased.

Hereinafter, a method for supporting the phosphors 16R, 16G, and 16B on the nonwoven fabrics 18R, 18G, and 18B will be described.
First, a large number of composite fibers 28 (see FIG. 7) having a predetermined length obtained by coating fibers 20 made of a high melting point material such as polypropylene with fibers 26 made of a low melting point material such as polyethylene are prepared. Is used to form a sheet-like aggregate (web) made up of a large number of these composite fibers 28.

  Next, the sheet-like assembly is heated at a temperature higher than the melting point of the fiber 26 made of the low-melting-point material constituting the composite fiber 28 and lower than the melting point of the fiber 20 made of the high-melting-point material. In addition to melting only the fibers 26 composed of the first nonwoven fabric 18R, the particulate red light emitting phosphor 16R is used as the original aggregate of the first nonwoven fabric 18R, and the particulate aggregate is used as the second nonwoven fabric 18G. A particulate blue light-emitting phosphor 16B is sprayed on the green light-emitting phosphor 16G and the aggregate of the third nonwoven fabric 18B.

As a result, the intersecting portions of the fibers 20 made of the high melting point material are bonded through the fibers 26 made of the melted low melting point material, thereby forming the sheet-like nonwoven fabrics 18R, 18G, and 18B. The phosphors 16R, 16G, and 16B are bonded and supported on the surfaces of the fibers 20 constituting the nonwoven fabrics 18R, 18G, and 18B through the fibers made of a molten low melting point material.
In the above method, by using the composite fiber 28 in which the fiber 20 made of the high melting point material is coated with the fiber 26 made of the low melting point material, only the fiber 26 made of the low melting point material is melted to function as an adhesive. Since the nonwoven fabrics 18R, 18G, and 18B can be formed and the phosphors 16R, 16G, and 16B can be supported on the surfaces of the fibers 20 constituting the nonwoven fabrics 18R, 18G, and 18B at substantially the same time, it is extremely easy to manufacture.

In addition to the above method, for example, the nonwoven fabric 18R, 18G, 18B is dipped in the dispersion resin liquid of the phosphor 16R, 16G, 16B and then dried, or from above the nonwoven fabric 18R, 18G, 18B, the phosphor 16R The phosphors 16R, 16G, and 16B may be attached to and supported on the surfaces of the fibers 20 constituting the nonwoven fabrics 18R, 18G, and 18B by dropping the dispersion resin liquid of 16G and 16B.
Further, by heating the nonwoven fabrics 18R, 18G, 18B and blowing the phosphors 16R, 16G, 16B in a state where the surfaces of the fibers 24 constituting the nonwoven fabrics 18R, 18G, 18B are melted, the nonwoven fabrics 18R, 18G, The phosphors 16R, 16G, and 16B can be attached and supported on the surface of the fiber 24 constituting the 18B.
Further, the phosphors 16R, 16G, and 16B heated at a high temperature are sprayed onto the nonwoven fabrics 18R, 18G, and 18B, and the nonwoven fabrics 18R, 18G, and 18B are partially melted to form the nonwoven fabrics 18R, 18G, and 18B. Alternatively, the phosphors 16R, 16G, and 16B may be attached to and supported on the surface of the fibers 20 to be performed.

  FIG. 8 shows a second planar light source device 30 according to the present invention. This second planar light source device 30 transmits the light emitted from the LED 14 to the back surface 12c of the light guide plate 12. As shown in FIG. A first non-woven fabric 18R carrying a red light emitting phosphor 16R that converts the wavelength of red visible light to emit, and a green light emitting phosphor 16G that converts the wavelength of green visible light to emit. The second non-woven fabric 18G is characterized in that a third non-woven fabric 18B comprising a phosphor 16B for emitting blue light that is emitted after being converted into blue visible light is disposed. The thickness of the light guide plate 12 is such that the visible light of the three colors of red visible light, green visible light, and blue visible light emitted from the phosphors 16R, 16G, and 16B is emitted from the light exit surface 12b without being mixed. The thickness is set, specifically, the thickness is set to 8 mm or less.

  In the second planar light source device 30, the light emitted from the LED 14 enters the light guide plate 12 and the light guide plate 72 from one end surface 12a of the light guide plate 12, and is then arranged on the rear surface 12c of the light guide plate. The phosphor 16R for red light emission carried on one nonwoven fabric 18R, the phosphor 16G for green light emission carried on the second nonwoven fabric 18G, and the phosphor 16B for blue light emission carried on the third nonwoven fabric 18B. By irradiation, visible light of three colors of red visible light, green visible light and blue visible light is emitted, and these three colors of visible light are transmitted through the inside of the light guide plate 12 and emitted from the light exit surface 12b to the outside. It has come to be.

In the second planar light source device 30, when the thickness of the light guide plate 12 is larger than 8 mm, red visible light, green visible light and blue visible light emitted from the phosphors 16R, 16G, and 16B. A plurality of colors of visible light (for example, yellow visible light in which red visible light and green visible light are mixed, light blue visible light in which green visible light and blue visible light are mixed, red) The visible light and the blue visible light are mixed with each other.

  In the above, the case where the three non-woven fabrics 18R, 18G, and 18B are arranged on the light exit surface 12b or the back surface 12c of the light guide plate 12 is illustrated, but the present invention is not limited to this, and the present invention is, in short, the light guide plate. A plurality of non-woven fabrics are arranged on the 12 light exit surface 12b or the back surface 12c, and each non-woven fabric is allowed to carry a phosphor that emits visible light having an emission color different from the emission color of the phosphor carried by the other nonwoven fabric. It ’s fine.

  Further, in the above, the case where the nonwoven fabrics 18R, 18G, and 18B are used as the fiber aggregate has been described as an example, but the present invention is not limited to this, and is formed by weaving a large number of fibers. A phosphor may be supported on the fibers constituting the woven fabric. Although this woven fabric does not reach the nonwoven fabrics 18R, 18G, and 18B, the surface area of the fiber per unit volume is large.

Further, in the above description, the case where the phosphors 16R, 16G, and 16B are carried on the “surface” of the fibers 20 constituting the nonwoven fabrics 18R, 18G, and 18B has been described as an example, but the present invention is not limited thereto. For example, the phosphor 16R is added to the fibers 20 constituting the nonwoven fabrics 18R, 18G, and 18B by kneading the particulate phosphors 16R, 16G, and 16B with the translucent fibers 20 made of a transparent resin or the like. 16G and 16B may be carried.
In this case, for example, after mixing a predetermined amount of particulate phosphor in an uncured transparent resin, the transparent resin is stretched and cured, and then cut into a predetermined length to obtain phosphor 16R, A large number of fibers mixed with 16G and 16B may be formed, and the nonwoven fabrics 18R, 18G and 18B may be formed using a large number of fibers mixed with such phosphors 16R, 16G and 16B.

It is a schematic sectional drawing of the 1st planar light source device which concerns on this invention. It is a top view of the 1st planar light source device which concerns on this invention. It is a perspective view which shows typically the 2nd nonwoven fabric which carry | supported fluorescent substance. It is the elements on larger scale which show typically the 2nd nonwoven fabric which carry | supported fluorescent substance. It is an enlarged view which shows typically the fiber which comprises a 2nd nonwoven fabric. It is sectional drawing which shows typically the fiber which comprises a 2nd nonwoven fabric. It is a schematic sectional drawing which shows a composite fiber. It is a schematic sectional drawing of the 2nd planar light source device which concerns on this invention. It is a schematic sectional drawing which shows the conventional planar light source device.

Explanation of symbols

10 First planar light source device
12 Light guide plate
12b Light emitting surface
14 LED
16R phosphor for red light emission
16G green phosphor
16B Blue phosphor
18R first non-woven fabric
18G second nonwoven fabric
18B Third nonwoven fabric
24 Light reflecting member
30 Second planar light source device

Claims (4)

  A light source that emits light having a wavelength that excites a phosphor; and a light guide plate having a light output surface on the surface. A plurality of fiber assemblies are disposed on the light output surface of the light guide plate, and each fiber assembly A planar light source device, characterized in that the body carries a phosphor that emits visible light having a light emission color different from the light emission color of the phosphor carried by an assembly of other fibers.   A light source that emits light having a wavelength that excites a phosphor; and a light guide plate having a light output surface on the surface. A plurality of fiber assemblies are disposed on the back surface of the light guide plate, and each fiber assembly. A planar light source device characterized in that a phosphor that emits visible light having an emission color different from the emission color of the phosphor carried by an assembly of other fibers is supported.   The planar shape according to claim 2, wherein the thickness of the light guide plate is set to a thickness that is radiated from a light exit surface without mixing visible light radiated from each fiber assembly. Light source device. The planar light source device according to any one of claims 1 to 3, wherein the aggregate of fibers is a nonwoven fabric, and a phosphor is supported on the fibers constituting the nonwoven fabric.

Images