JPH0679094B2 - Light collector - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a solar energy utilization apparatus, and is particularly suitable for concentrating sunlight without tracking the sun and supplying the condensed light to others. The present invention relates to a non-tracking light collector.

[Background of the Invention]

In the conventional non-tracking light-collecting device, as shown in FIG. 2, a fluorescent material layer is provided on the surface of a transparent flat plate 3, and it is guided to the end face of the flat plate by utilizing wavelength conversion and total reflection of sunlight. It was converted into electricity by the photocell 4 provided with the end face, or was converted into heat by the heat collector. This device can collect sunlight more than 100 times without tracking the sun, but the collected sunlight is converted into electricity or heat at the end face of the flat plate and used. No consideration was given to taking it out of the flat plate and transmitting the light as it is far from the flat plate for use.

[Object of the Invention]

Therefore, the object of the present invention is to provide a non-tracking light concentrating device that can condense sunlight 100 times or more without tracking the sun and efficiently extract the condensed light to the outside. Especially.

[Outline of Invention]

The light-collecting device of the present invention is a transparent body having a plane portion inclined with respect to the luminescence layer, directly or through a transparent body, on at least one surface of the luminescence layer, and the area of the surface facing the luminescence layer is It is characterized in that a light guide means made of a transparent material smaller than the area of the luminescence layer is provided.

Example of Invention

An embodiment of the present invention will be described below with reference to FIG. First
FIG. 1 is a partially cutaway view showing the structure of a non-tracking light collector according to an embodiment of the present invention. In FIG. 1, reference numeral 11 is a transparent plate, and a material having a low light absorptivity such as glass, quartz, acrylic resin, or polycarbonate resin is suitable. In this embodiment, a glass plate is used as the transparent body 11. This transparent plate 11
A substance that absorbs sunlight in a specific wavelength range and emits light having a spectrum different from the absorption spectrum, that is, the luminescent layers 12 and 13 is provided on the back surface of the. Inorganic or organic phosphors, phosphors and the like are suitable as the luminescent material. The property may be liquid or solid. In this embodiment, a ZnS: Ag phosphor is used as the luminescence layer 12, and a ZnS: Cu phosphor is used as the luminescence layer 13. The characteristics of ZnS: Ag and ZnS: Cu phosphors are described in Section 3.
Shown in the figure. In FIG. 3, the horizontal axis represents the wavelength of light and the vertical axis represents the relative value of the light intensity absorbed or emitted. In the figure, hatched curves 51 and 52 are ZnS: Ag and
The absorption spectrum of the ZnS: Cu phosphor is shown, and the solid line 53 and the broken line 54 show the emission spectrum of each phosphor. From Fig. 3, for example, the absorption spectrum of ZnS: Cu phosphor
Since the spectrum overlapping portion 55 of 52 and the emission spectrum 54 is small, the light emitted from the ZnS: Cu phosphor is again ZnS:
It is incident on the Cu phosphor and is hardly absorbed.

The above-mentioned ZnS: Ag phosphor and ZnS: Cu phosphor each have a refractive index n, n ₂ of about 2.5, which is almost equal, but larger than the refractive index n ₀ = 1.4 of the glass of the transparent plate 11. . Therefore, the light extraction projections 14 were provided on the surface of the luminescence layer 13.
The reason will be described below. FIG. 4 is a part of a sectional view taken along the line AA in FIG. In FIG. 4, the respective refractive indexes of the transparent plate 11, the luminescence layer 12, and the luminescence layer 13 are shown.
For convenience of description, n ₀ , n ₁ , n ₂ are set to n ₂ > n ₁ > n ₀ . Now, it is assumed that most of the sunlight 15 incident on the transparent plate 11 is transmitted through the transparent plate 11 and a part of the sunlight 15 is wavelength-converted at a point B in the luminescence layer 12. The light whose wavelength is converted at the point B is isotropically emitted from the point B. Of this isotropically emitted light, the following equation Light incident on the interface 61 between the transparent plate 11 and the luminescence layer 12 at an incident angle larger than the critical angle θ _C1 determined by is totally reflected at the interface 61. This totally reflected light is n ₂ > n ₁ and therefore passes through the interface 62 between the luminescent layers 12 and 13 and enters the luminescent layer 13. On the other hand, light incident on the interface 61 at an incident angle smaller than the critical angle θ _C1 passes through the interface 61 and enters the surface 63 of the transparent plate 11. Of the light incident on this surface 63, the following formula Light incident on the surface 63 at an incident angle larger than the critical angle θ _C3 determined by is totally reflected by the surface 63. Since the light totally reflected is n ₂ > n ₁ > n _0, it passes through the interfaces 61 and 62 and enters the luminescence layer 13. The incident angle θ _{1 at the} interface 61 where the light emitted at the point B becomes θ _{C3 on the} surface 63 is given by the following equation.

Similarly, of the light emitted by wavelength conversion at the point C in the luminescence layer 13, the light incident on the interface 62 at an incident angle larger than θ ₂ given by the following equation is totally reflected by the surface 63. And returns to the luminescence layer 13 again.

Further, the critical angle θ _C4 with respect to the light emitted from the surface 64 of the luminescence layer 13 is equal to θ ₂ .

Therefore, of the light emitted at points B and C, the surface 63
Although the light totally reflected by the light always returns to the luminescence layer 13, the light totally reflected by the surface 64 does not necessarily enter the transparent body 11. Therefore, in order to efficiently extract light to the outside, it is necessary to provide the light extraction protrusion on the surface of the layer having the highest refractive index.

In FIG. 1, the projection 14 for extracting light has a triangular pyramid shape,
It is a transparent material, and its refractive index is close to that of the person to whom it is attached. The light extraction protrusions 14 have a triangular pyramid shape for the following optical reasons. Transparent plate 11,
In order to take out the light collected by the wavelength conversion and total reflection in the light collecting transparent plate 16 composed of the luminescence layers 12 and 13 to the outside of the light collecting transparent plate 16, the total reflection is performed at the extraction position. It suffices to create surface conditions that cannot meet the conditions. As the method, a method of taking out from the end surface of the light collecting transparent plate 16, a method of providing a recess in the light collecting transparent plate 16, and the like are conceivable. However, in these methods, total reflection is performed inside the light collecting transparent plate 16. It is difficult to break the condition of total reflection for the light of a wide angle range that is repeated, and the light cannot be extracted efficiently.
Therefore, projections are provided on the transparent plate for light collection, and the shape is a triangular pyramid. A detailed view of the light extraction projection 14 in FIG. 1 is shown in FIG. In FIG. 5, points D, E, F, and G are the corner vertices of a triangular pyramid. The arrow in FIG. 5 is a typical light path. Of the light incident on the light extraction protrusions, one of the most severe incident light to be extracted to the outside is the surface DEF that is in close contact with the luminescence layer 13.
The light is incident on the projection for extracting light substantially parallel to. In order to take out this light to the outside, the angle α formed by the surface DEF and the surface DEG is set so as to satisfy the following expression from the condition that the surface DEG is not totally reflected.

However, n = n ₃ = n ₂ n ₂ = refractive index of the luminescent layer 13 n ₃ = refractive index of the projection 14 for light extraction. The surface EFG and surface DFG were also set so as to satisfy the equation (5).

Another most severe incident light is the light that is incident almost parallel to the surface EFG. However, as shown in the optical path diagram seen from the surface DEF shown in FIG. 6, the light totally reflected by the surface EFG is
The angle of incidence on the surface DEG becomes larger than the total reflection condition for incidence. Therefore, surface EFG, surface DEG,
Light incident parallel to the surface DFG or the like may be totally reflected once or twice, but there is no problem because it goes out of the light extraction protrusion after that. Even if a polygonal pyramid having a quadrangular pyramid or more or a shape obtained by cutting out a part thereof is used, the effect is almost unchanged.

In FIG. 1, the curved mirror 17 is arranged so that its focal position is inside the projection 14 for extracting light. In this embodiment, the curved mirror 17 is an ellipsoidal mirror, and one focus position of the curved mirror 17 is arranged inside the light extraction protrusion 14 and the other focus position thereof is arranged near the entrance of the light guide 18. As a result, the light in a wide angle range emitted from the light extraction projection 14 is condensed by the curved mirror 17 (elliptical mirror) and efficiently enters the light guide 18.

In FIG. 1, a reflecting layer 18 is provided on the end surface of the light collecting transparent plate 11 by vapor deposition of silver or the like to prevent loss of light from the end surface.

The operation of the non-tracking light-collecting device shown in FIG. 1 according to the embodiment of the present invention will be described below. The sunlight 15 incident on the transparent plate 16 for condensing is wavelength-converted by the luminescence layer 12 or 13 and isotropically radiated, but the total reflection condition of several tens% or more of the emitted light is satisfied. The light is repeatedly totally reflected and emitted from the projection 14 for extracting light. The emitted light is condensed by the curved mirror 17, enters the light guide 18, and is transmitted to the light utilization unit. The condensing magnification N and the efficiency η for all incident sunlight by this non-tracking condensing device are given by the following equations.

However, N = condensing magnification η = efficiency of condensing device η ₁ = total transmission efficiency of the concentrating transparent plate and the light extraction part A ₀ = sunlight receiving area of the concentrating transparent plate A ₁ = of the light extraction part Area I ₀ = Intensity of sunlight incident on the transparent plate for light collection I ₁ = Intensity of light emitted from projections for extracting light P = Conversion probability of the luminescence layer for sunlight N from the above equation The transmission efficiency η ₁ needs to be high in order to increase the value of η _1, but as described above, there is almost no loss in the light extraction protrusions 14, and therefore η ₁ can be about 0.9, which is 0.5 compared to 0.5 when extracting from the end face. Is. Therefore, A ₀ / A ₁ is 10000, P is 0.1, η ₁ is 0.9
Then, the condensing magnification N can be 900 and the efficiency η can be 0.09.

As described above, according to the present embodiment, it is possible to efficiently extract the light condensed at a high condensing magnification to the outside without tracking the sun.

FIG. 7 is a bird's eye view showing another embodiment of the light extraction projection. In the figure, one surface of a triangular pyramid-shaped light extraction projection 82 is provided so as to coincide with the bottom surface of the projection extension portion 81 obtained by cutting out one section of the triangular pyramid. Then, the light that has passed through the surface HIJ closely attached to the transparent plate for condensing and is incident on the side surface IJKL is reflected. Therefore, 3 of the protrusion extension 81 including the side IJKL
A reflective surface is formed by depositing silver on one side surface. The anti-slope surface may be totally reflected by setting the angle β formed by the side surface and the surface HIJ so as to satisfy the following expression.

By configuring the light extraction protrusions in this manner, the light emitting portion can be separated from the light collecting transparent plate. Therefore, there is an effect that the arrangement of the curved mirror 14 becomes easy in design.

FIG. 8 is a sectional view showing another embodiment of the non-tracking light collecting device of the present invention. In FIG. 8, a luminescence layer 92 is provided inside a spherical shell-shaped transparent body sphere 91. Further, a light extraction projection 93 is provided on a part of the surface of the transparent body sphere 91, and a curved mirror 94 is provided around the light extraction projection 93. Further, in the present embodiment, the projection 93 for extracting light is attached to the transparent body sphere 91 by providing an outlet, but the transparent body sphere is attached.
May be mounted on 91 curved surfaces.

According to the present embodiment described above, since there is no end face as compared with the flat light collecting transparent body, it is possible to eliminate light loss at the end face and improve efficiency. Further, even if the incident direction of sunlight changes, the projected area of the spherical shell-shaped transparent sphere does not change, so that there is an effect that the amount of light that can be extracted does not change.

FIG. 9 is a sectional view showing another embodiment of the transparent plate 16 for condensing light in FIG. In the figure, (a) is a light-collecting transparent plate 16 composed only of the luminescence layer 12, and (b) is composed of the luminescence layer 12 and the transparent plate 11, and is a projection for extracting light.
When 14 is attached to the side of the transparent plate 11, (c) sandwiches the luminescent layer 12 between the transparent plates 11, and when the structure has a Saint-German structure, (d) shows the luminescent layer 12 and the luminescent layer 12 on both sides of the transparent plate 11.
When 13 is provided, (e) is a transparent transparent plate for condensing the structure of (b).
The case where 16 is provided with spaces 31 and 32 and covered with cover glasses 33 and 34 is shown. From these structures, a structure suitable for the characteristics of the luminescence layer and the use environment can be selected.

FIG. 10 is a bird's-eye view showing another embodiment of the light extraction projection 14 of FIG. In FIG. 10, (a) shows multiple donut ring-shaped projections 14 each having a triangular cross section, and (b) shows a prism having the same triangular cross section provided in a ring shape. . With this configuration, it is possible to reduce the height of the light extraction protrusion 14 with respect to the bottom area.

〔The invention's effect〕

According to the present invention, the light extraction part is transmitted by utilizing wavelength conversion and total reflection, and the light extraction part is emitted from the light extraction protrusion having a shape of a polygonal pyramid or a combination of polygonal cones. Since the light can be efficiently extracted by the curved mirror for condensing the light, it is possible to obtain a non-tracking light condensing device having high efficiency and a condensing magnification of approximately 2 times.

[Brief description of drawings]

1 is a structural view showing an embodiment of the present invention, FIG. 2 is a bird's-eye view showing a conventional example, FIG. 3 is a characteristic view of a luminescent body, and FIG. 4 is a sectional view taken along the line AA of FIG. Partly, FIG. 5 is a bird's-eye view of the light extraction projection 14 of FIG. 1, FIG. 6 is a plan view of FIG. 5, and FIGS. 7 and 10 are light extraction projections of FIG.
14 is a bird's-eye view showing another embodiment, FIG. 8 is a cross-sectional view showing another embodiment of the present invention, and FIG. 9 is a light-collecting transparent plate of FIG.
FIG. 16 is a cross-sectional view showing another embodiment of 16. 11 …… Transparent plate, 12,13 …… Luminescence layer, 14 …… Light extraction protrusion, 16 …… Concentrating transparent plate, 17 …… Curved mirror,
18 …… Reflecting layer, 19 …… Light guide.

Claims (5)

[Claims] 1. A transparent body having a flat surface portion, which is inclined with respect to the luminescence layer, directly or through a transparent body, on at least one surface of the luminescence layer, wherein the area of the surface facing the luminescence layer is the luminescent layer. A light condensing device provided with a transparent member having a smaller area than that of the condensing device. 2. The refractive index of the transparent body as the light guide means and the refractive index of the transparent body interposed between the luminescence layer and the light guide means are the same or close to each other. The light condensing device according to claim 1. 3. The light concentrating device according to claim 1, wherein the luminescence layer contains two or more kinds of luminescence having different excitation effects. 4. The light-collecting device according to claim 3, wherein the luminescence layer has a multi-layered structure of two or more kinds, and each layer has a different excitation action. 5. A light-collecting device according to claim 3, wherein each of the luminescent layers having a multilayer structure has different refractive indexes.