JPS63133111A - Condenser - Google Patents

Abstract

PURPOSE:To efficiently radiate the light condensed in the edge part to the outside by inclining the edge part in the direction perpendicular to the total reflection face of a light-transmissive medium. CONSTITUTION:With respect to a condenser where total reflection in the light- transmissive medium is used to condense the light in the edge part of the light- transmissive medium, the edge part is inclined in the direction perpendicular to the rotal reflection face of the light-transmissive medium. For example, if the sunbeam is projected to a resin plate 1 in which a fluorescent dye is dissolved and dispersed, fluorescence is radiated from the fluorescent dye and is condensed toward an edge part 1b of the resin plate 1 by rotal reflection in the resin plate, and a part of this fluorescence is transmitted through the edge part 1b and is used to generate electricity by the sunbeam. Though a part of the condensed light is not transmitted through the edge part 1b and is gradually attenuated in the resin plate 1, all of the condensed light is transmitted from the edge part 1b and from near this part because the edge part 1b is inclined, and the generated electric energy is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a light concentrator that utilizes total internal reflection within a transparent medium.

(Background Art) In recent years, the number of devices that use solar energy as a power source has been increasing, but devices that use solar energy have the disadvantage of being more expensive than devices that use other forms of energy. This is mainly due to the high cost of solar cells, tracking solar energy concentrators, etc. Therefore, conventionally, luminescent solar concentrators (luminescent solar concentrators), which aim to reduce costs by reducing the area of solar cells, have been developed.
Research is being conducted using the ``oncentrater''.

For example, when a transparent resin plate containing a fluorescent dye dissolved and dispersed therein is exposed to sunlight, the fluorescent dye absorbs light energy and emits fluorescence. This emitted light is captured by total internal reflection inside the resin plate and collected at the edge of the resin plate. Therefore, solar power generation can be efficiently performed by attaching a solar cell to the edge. Concentration of the light captured on the resin plate in this way
The efficiency of is proportional to the ratio of surface area to edge and also depends on the proportion radiated from the edge. That is,
Not all of the light collected by total internal reflection is emitted from the edges, and some light is re-reflected inside. This means that regardless of the method of mounting the solar cells, the amount of power generated is limited by the radiation efficiency from the edges. The reason why reflection occurs at the edge is that when a part of the total internally reflected light is incident on the interface between the edge and the air, the incident angle is larger than the critical angle, and the light is This is because the light is reflected back into the resin plate at the edge.

Therefore, if the thickness of the resin plate is constant and the edge is perpendicular to the surface of the resin plate, the reflected light at the edge will travel back and forth within the resin plate many times and will gradually attenuate. To go.

As a result of the above, out of the light collected toward the edge,
It is desirable to efficiently generate solar power using a concentrator that emits as much light as possible from the edge and its vicinity.

(Object of the invention) The present invention has been made in view of the above points, and
The purpose is to provide a concentrator that efficiently radiates the light collected at the edge to the outside.

(Disclosure of the Invention) The present invention provides a concentrator that uses total reflection within a transparent medium to condense light onto an edge of the transparent medium, the edge of which is transparent. It is characterized by being tilted with respect to the direction perpendicular to the total reflection surface of the reflective medium, and the light is efficiently radiated to the outside from the tilted edge.

For example, when a resin plate containing dissolved and dispersed fluorescent dye is irradiated with sunlight, fluorescence is emitted from the fluorescent dye, and this fluorescence is collected toward the edge of the resin plate by total reflection inside the resin plate. This light is transmitted through the edges and can be used to generate solar power. A part of the collected light does not pass through the edge and gradually attenuates within the resin plate, but by giving the edge an inclination, the collected light is transferred to the edge and its surroundings. It is possible to increase the amount of power generation by allowing all of the light to pass through from the vicinity. Note that the same effect can be obtained by using a glass plate or a composite material of glass and resin instead of the resin plate.

Now, as shown in FIG. 2, it is assumed that a resin plate (1) with a constant thickness is placed in the air, and a fluorescent dye is uniformly dissolved and dispersed within the resin plate (1).

When sunlight is irradiated from the large area direction of the resin plate (1),
The dye inside the resin plate (1) absorbs sunlight energy and emits fluorescence. The emission direction of the fluorescence is 360°
Assume that it is uniform in the three-dimensional direction. Of the emitted fluorescence,
The critical angle determined by the refractive index n,* of the resin plate (1) and the refractive index nA of air is θc=sin-'(71,A/
Light incident on the interface between the resin plate (1) and the air at an incident angle larger than 7'l, R)) is concentrated toward the edge (1a) by total internal reflection. However, while being concentrated at the edge (1a) by total internal reflection,
1a) There are cases where the light is re-reflected.

For example, FIG. 3 shows a case where polymethyl methacrylate (hereinafter referred to as PMMA) is used for the resin plate (1). P
The refractive index of MMA is 71. R=1,5, the refractive index of air is '11. When A=1, 0, θc=426. If the angle of incidence on the lower surface of the resin plate (1) is 42° or more, as shown in FIG. Since the angle is θc-42°, this light is totally reflected again at the edge (1a) and enters the upper surface at an angle of 42° or more, so that it is totally reflected again. Therefore, as long as this process is repeated, the light will not be able to exit to the outside, and will gradually attenuate as it travels back and forth inside the resin plate (1).

Furthermore, if the angle of incidence on the bottom surface of the resin plate (1) is 48° or more, it will be totally reflected on the bottom surface, as shown in Figure 3(b).
It is incident at the edge (la)'\42° or less.

If the angle of incidence on the bottom surface of the resin plate (1) is slightly larger than 48°, the angle of incidence on the edge (la)'\ will be slightly smaller than 42°, and this light will be considered as transmitted light. Become. Furthermore, if the angle of incidence on the lower surface of the resin plate (1) is less than 42°, all of the light will be transmitted and will not be focused on the edge (1a).

The above can be summarized as follows.

(8) Light with an incident angle of θ·42° is not focused on the edge.

(B) Light with an incident angle of 42°≦θ≦486 is focused on the edge, but does not pass through the edge.

(C) Light with an incident angle of 48° x 90° is condensed at the edge and transmitted from the edge.

Further, this also holds true for the incident light on the top surface and the side surface of the resin plate (1).

Assuming that the luminescence of the fluorescent dye is uniform in 360° three-dimensional directions, the light collection efficiency at the edge (1a) is expressed as cos θ, where θ is the incident angle. For example, when a solar cell is attached to the edge (1a), fluorescent energy (
100X cos θ)% will be used for conversion into electrical energy. In the case of PMMA in the previous example, cos4
8' ball is 67%.

However, in reality, an average of 74% of the fluorescence of cos 42° is collected at the edge (1a), and 7% of this is lost because it does not pass through to the outside. Therefore, in order to reduce this 7% loss, as shown in FIG.
Use. That is, in FIG. 4, the edge portion (1b
) is the inclination angle ψ with respect to the plane perpendicular to the surface of the resin plate (1).
It is only tilted.

First, the case shown in FIG. 4(b) will be explained. Resin plate (
1) Light incident on the bottom surface at an angle θ (θ≧θC>) is totally reflected and enters the edge (lb) at an angle ξ.At this time, if ξ〈θC, all of the light reflected from the bottom surface is Edge (1b)
Transparent. Since ξ-1π/2-ψ-θ1, the transmission conditional expression is as follows.

1π/2−ψ−θ1×θC...■ Here, (a) When π/2−ψ−θ≧O, that is, when θ≦π/2−ψ, ■The formula is ψ>π /2−θ−θC (b) When π/2−ψ−θ×O, that is, when θ)・π/2−θC, the formula (2) becomes ψ×π/2−θ−θC. Since there is reflected light from the bottom surface, θC≦θ≦
π/'2 Therefore, =8- (a') When O<ψ, the condition (a) above always holds within the range θC≦θ≦π/2, as follows: ψ〉π/2−2θC.

(bo) When ψ - π/2, in order for the condition (b) above to always hold within the range θC≦θ≦π/2, ψ must be less than θC. Here, since θc>0, ψ〈
O, which contradicts the assumption O×ψ×π/2. Therefore, there is no ψ that satisfies the condition (bo).

Next, the case of FIG. 4(a) will be explained. Resin plate (
1) The light incident on the upper surface at an angle θ (θ≧θC) is totally reflected and enters the edge portion (1b) at an angle ξ. Here,
The critical condition for total reflection at the edge (1b) is ξ2α+ψ−
π/2+ψ-θ-θC1゛, θ=π/2-θC+ψ=α
IIIIX+ψ, and with this angle as the boundary, total reflection occurs when θ≦αll1aX+ψ, and transmission occurs when θ>aIllaX+ψ.

The light totally reflected at the edge (lb) is incident on the lower surface of the resin plate (1) at an angle β. The transmission condition for this incident light is β-12ψ-θ1×θC.

Here, (c) When 2ψ−θ≧0 °, θ≦2ψ, 2ψ−
θ × θC In other words, ψ × (θ + θc)/2 (d) 2ψ−θ (Q , −, when θ〉2ψ, 2ψ
-θ>-θC In other words, ψ>(θ-θc)/2. Since there is reflected light from the top surface, θC≦θ≦
π/2 Therefore, when (Co)ψ≦π/4, the condition (e) above (θ
In order to always hold within the range of 10 θc)/2 or θC≦θ≦π/2, it is sufficient that ψ is less than θC.

(d') When θc/2≦ψ, the condition ψ〉(
In order for θ-θc)/2 to always hold within the range θC≦θ≦π/2, it is sufficient that ψ>(π/2-θc)/2.

To summarize the above, in the range of θC≦θ≦π/2, the incident light from the bottom surface of the resin plate (1) to the edge (1b) and the incident light from the top surface of the resin plate (1) to the edge (1b) The conditions for all incident light to pass through and to the bottom surface are: (a') When O<ψ<π/2, ψ>π/2-2θC (c') 0<ψ≦π/ When 4, ψ θC (do) θc
When /2≦ψ<π/2, it is necessary to satisfy the following combination of ψ>(π/2−θC)/2.

(i) Combination of condition (a゛) and condition (Co) 0kuψ
When ≦π/4, π/2−2θC〈ψ×θC π/4〈ψ〈π/2, π/2−2θc×ψ (ii) Combination of condition (a゛) and condition (do) θc
When /2≦ψ〈π/2, if θC≦π/6, then ψ(π/2−θc)/2 If π/6×θc×π/2, then ψ×π/2−2θC O When ψ θc/2, π/2-2 θe< ψ If either of the above conditions (i) or (ii) is satisfied,
The light focused in the direction of the edge (1b) is
) and its vicinity (lower surface portion of the resin plate (1)). Therefore, if solar cells are placed at the edge (1b) and the length of the bottom surface X = (X l + X 2 ) in Figure 4, all of the concentrated light can be used for power generation. The maximum value Xmax of the length X of the light emitting part on the bottom surface is: Xmax=X+(max)+X2Here,
X, (max) is the maximum value of X, and the resin plate (1
) is the plate thickness d, and the maximum value of the angle β is βIll a X. Since X 1 (max) = d “tanβ1naX,

Next, examples and comparative examples will be shown.

K1 燵Y Dimensions: Height 20 OrIls+, Width 200mm, Thickness 10
The edge (1b) of the resin plate (1) made of m+n PMMA
) was tilted at an angle of inclination ψ as shown in FIG. This P
MMA contains “0RANGE240” as a fluorescent dye.
(trade name, manufactured by BASF) in an amount equivalent to 0.002% by weight. The critical angle is θCξ42° from the refractive index na=1.5 of PMMA and the refractive index 7′l, A−1,0 of air. The inclination angle ψ was set to ψ-10° from the condition (i), when 0 ψ≦π/4, π/2-2θC ψ θC 6 @ ψ 42 .

The maximum angle of the light reflected at the edge (1b) and incident on the lower surface is βmax= lξmin+ψ-π/2+=IoC+ψ-
π/21 - 142° + 10° - 9061 = 386 - 12 = Therefore, the maximum length of the light emitting part on the bottom surface X+++ax =
d(tanβmax+tanψ)−10(jan38
'+janlO')-9,6 (mm). Therefore, as shown in FIG. 1, a solar cell (S,) with a length of L + "" 10.0 IOm is placed on the edge (1b) of the resin plate (1), and a solar cell (S,) with a length of L2 = 10.0 IOm is placed on the light emitting part of the lower surface. 10.
A 0 mm solar cell (S2) was attached to each, and the power generation amount p(w) was measured under sunlight, and the results are shown in Table 1.

K1 Salmon λ In Example 1, solar cells (Sl) and (S2) were installed under the same conditions as in Example 1, except that the length of the bottom-mounted solar cell (S2) was changed to Lz = 6.0 ml11, and sunlight The power generation amount P (W) was measured under the following conditions, and the results are shown in Table 1.

In Example 1, the solar cells (s+) and (S2) were installed under the same conditions as in Example 1, except that the inclination angle ψ was Oo, and the power generation amount p (w) was measured under sunlight. , the results are shown in Table 1.

In Example 2, the solar cell (Sl), (82) was installed under the same conditions as Example 2, except that the inclination angle ψ was Oo, and the power generation amount p (w) under sunlight was The results are shown in Table 1.

Table 1 As is clear from Table 1, when solar cells of the same area are installed, the amount of power generated is approximately 10% higher when the edges are sloped, and the light collecting performance is improved. It can be seen that the results are better.

(Effects of the Invention) As described above, the present invention provides a condenser that uses total reflection within a transparent medium to condense light onto an edge of the transparent medium. Since the portion is inclined with respect to the direction perpendicular to the total reflection surface of the light-transmitting medium, there is an effect that the light collected at the edge portion can be efficiently radiated to the outside.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an embodiment of the present invention, Figs. 2 and 3 (a) and (b) are explanatory diagrams of the operation of the conventional example, and Figs. 4 (a) and (b).
) is an explanatory diagram of the operation of the present invention. (1) is a resin plate, and <1b) is an edge portion.

Claims (3)

[Claims] (1) In a condenser that uses total reflection within a transparent medium to condense light onto an edge of the transparent medium, the edge is a total reflection surface of the transparent medium. A concentrator characterized by being tilted with respect to a direction perpendicular to the direction. (2) The condenser according to claim 1, wherein the light-transmitting medium is one of resin, glass, and a composite thereof. (3) The condenser according to claim 1 or 2, characterized in that a fluorescent substance is contained inside the light-transmitting medium.