WO2012026572A1

WO2012026572A1 - Light-condensing device, light power generation device, and photothermal conversion device

Info

Publication number: WO2012026572A1
Application number: PCT/JP2011/069268
Authority: WO
Inventors: 達雄丹羽; 和歌奈内田
Original assignee: 株式会社ニコン
Priority date: 2010-08-26
Filing date: 2011-08-26
Publication date: 2012-03-01
Also published as: JPWO2012026572A1

Abstract

A light-condensing device comprises: a light-condensing lens; and a light-condensing optical element having an incident surface through which light condensed by the light-condensing lens enters, a back surface which is opposed to the incident surface, a first end surface which intersects the light axis of the light-condensing lens between the incident surface and the back surface, and a second end surface which faces the first end surface between the incident surface and the back surface, wherein the light-condensing optical element is composed of a transparent medium. The first end surface reflects light that enters the inside of the light-condensing optical element through the incident surface, the incident surface and the back surface totally reflect light that is reflected by the first end surface, and light that is reflected by the first end surface, light that is totally reflected by the incident surface and light that is totally reflected by the back surface enter the second end surface.

Description

Condensing device, photovoltaic power generation device, and photothermal conversion device

The present invention relates to a condensing device that condenses light incident on an incident surface in the direction of the end surface, and a photovoltaic device and a photothermal conversion device using the same.

Solar cells that convert light energy into electrical energy are composed of materials such as silicon-based, compound-based, organic-based, and dye-sensitized systems in terms of photoelectric conversion material classification. A typical solar battery cell has a power conversion efficiency of about 10 to 20%. In contrast, the radiation spectrum range of sunlight is divided into a plurality of wavelength bands, and a plurality of semiconductor layers with band gaps optimal for photoelectric conversion of light in each wavelength band are stacked, so that the conversion efficiency to power is 40. A multi-junction solar cell increased to about% has been developed.

However, the high-efficiency solar cells as described above are extremely expensive and difficult to use except for special applications such as aerospace. In view of this, a concentrating solar cell module has been devised that condenses and enters sunlight into a small cell to reduce costs and to perform solar power generation with high efficiency. As a condensing form, a lens condensing type that condenses sunlight with a Fresnel lens or a reflecting mirror and directly enters the solar cell (see Patent Document 1 and Patent Document 2), on a fluorescent plate in which fluorescent particles are dispersed Fluorescent plate condensing type (refer to Patent Document 3), in which sunlight is incident and the fluorescence generated in the plate is led out and collected to the side of the plate, sunlight is applied to the plate between which the hologram film and solar cells are sandwiched A spectral condensing type (see Patent Document 4) that guides light diffracted by a hologram film to a solar battery cell has been proposed.

Japanese National Table 2005-142373 Japanese Unexamined Patent Publication No. 2005-217224 US Patent Application Publication No. 2006/0107993 US Pat. No. 6,274,860

However, in the conventional lens condensing type condensing device, a relatively large lens (or reflecting mirror) and a solar battery cell corresponding to each lens (or each reflecting mirror) are provided. The apparatus is increased in size according to the focal length of each reflector. In the fluorescent plate condensing type concentrating device and the spectroscopic concentrating type condensing device, the dimension (thickness) of the module in the optical axis direction can be reduced, but there is room for improvement in terms of wavelength dependency and conversion efficiency. is there.

According to the first aspect of the present invention, the condensing device includes a condensing lens, an incident surface on which light collected by the condensing lens is incident, a back surface facing the incident surface, and the incident surface and the back surface. A condensing optical element having a first end surface that intersects the optical axis of the condensing lens and a second end surface that opposes the first end surface between the incident surface and the back surface, and is formed of a transparent medium; Is provided. The first end surface reflects light incident from the incident surface into the condensing optical element, and the incident surface and the back surface totally reflect light reflected by the first end surface, and light reflected by the first end surface; The light totally reflected by the incident surface and the light totally reflected by the back surface are incident on the second end surface.
According to the second aspect of the present invention, in the light condensing device according to the first aspect, the minimum incident angle of the light ray included in the light incident on the first end surface from the incident surface into the condensing optical element is The inclination angle of the first end surface with respect to the incident surface may be set so as to be equal to or greater than the total reflection critical angle at the first end surface.
According to the third aspect of the present invention, in the light condensing device according to the first or second aspect, the minimum incidence of the light beam included in the light incident on the first end surface from the incident surface into the condensing optical element. The numerical aperture of the condenser lens may be set so that the angle is equal to or greater than the total reflection critical angle at the first end face.
According to the fourth aspect of the present invention, in the light condensing device according to any one of the first to third aspects, the light beam included in the light incident on the first end surface after entering the condensing optical element from the incident surface. The refractive index of the condensing optical element may be set so that the minimum incident angle is equal to or greater than the total reflection critical angle at the first end face.
According to the fifth aspect of the present invention, in the condensing device according to any one of the first to fourth aspects, the condensing lens and the condensing optical element are incident on the inside of the condensing optical element from the incident surface. The light incident on the one end face may be disposed so as to focus on the first end face.
According to the sixth aspect of the present invention, in the condensing device according to any one of the first to fifth aspects, the condensing optical element is in contact with the incident surface and the back surface and between the first end surface and the second end surface. The first side surface and the second side surface are opposite to each other, and the first side surface and the second side surface totally reflect the light reflected by the first end surface, the incident surface, and the back surface, and are reflected by the first end surface. The light, the light totally reflected by the incident surface, the light totally reflected by the back surface, the light totally reflected by the first side surface, and the light totally reflected by the second side surface may be incident on the second end surface.
According to the seventh aspect of the present invention, in the condensing device according to any one of the first to sixth aspects, the plurality of condensing lenses, each of which is a condensing lens, are arranged, and the condensing optical element is It may have a plurality of first end surfaces which are first end surfaces and may be formed integrally.
According to the eighth aspect of the present invention, in the light condensing device according to the sixth aspect, a plurality of condensing lenses, each of which is a condensing lens, are arranged, and the condensing optical element is a plurality of elements each of which is a first end face. The first end face, the first side face corresponding to the plurality of first end faces in common, and the plurality of second side faces, each of which is a second side face, may be integrally formed.
According to the ninth aspect of the present invention, in the light condensing device of the seventh or eighth aspect, the plurality of condensing lenses are arranged in a matrix composed of a plurality of rows and a plurality of columns, and condensing optics. The element has a plurality of first end surfaces, a first side surface, and a plurality of second side surfaces corresponding to the condensing lenses in a plurality of rows among the plurality of condensing lenses, and corresponds to the plurality of rows. May be integrally molded.
According to the tenth aspect of the present invention, in the light collecting device according to the ninth aspect, the light reflected by each of the plurality of first end faces is blocked by the other first end face among the plurality of first end faces. It may be inclined with respect to the extending direction of each row.
According to the eleventh aspect of the present invention, in the light collecting device according to any one of the first to tenth aspects, the distance between the first end surface and the second end surface is greater than the distance between the incident surface and the back surface. It may be large enough.
According to the twelfth aspect of the present invention, in the condensing device according to any one of the first to eleventh aspects, the light incident on the incident surface may be obtained by the sunlight collecting the sunlight by the condensing lens. good.
According to the thirteenth aspect of the present invention, in the light collecting device according to any one of the first to twelfth aspects, the incident surface and the back surface may be substantially parallel to each other.
According to a fourteenth aspect of the present invention, a photovoltaic device includes the condensing device according to any one of the first to thirteenth aspects, and a photoelectric conversion element that photoelectrically converts light incident on the second end face.
According to a fifteenth aspect of the present invention, a photothermal conversion device includes the condensing device according to any one of the first to thirteenth aspects and a photothermal conversion element that photothermally converts light incident on the second end face.

According to the light collecting device, photovoltaic device and photothermal conversion device of the present invention, light energy such as sunlight can be used efficiently.

It is an external appearance perspective view of a photovoltaic device. It is a conceptual diagram for demonstrating the principle of a condensing device. It is a figure which shows the propagation state of the light condensed and incident on the condensing optical element with the condensing lens by the simulation of ray tracing. It is a figure which expands and shows the propagation of the light in the vicinity part of a condensing reflective surface. It is the top view and side view of a condensing optical element. It is the perspective view which looked at one element unit of a condensing optical element from diagonally upward. It is a table | surface which shows the relationship between the wavelength and refractive index in PMMA. It is a graph showing the radiation spectrum distribution of sunlight. It is a figure which shows the simulation of ray tracing in the attitude | position position which looked at the condensing device from the side. It is a figure which shows the simulation of ray tracing in the attitude | position position which looked at the condensing device from diagonally upward. It is a figure which shows the simulation of the ray tracing in the attitude | position position which looked at the condensing optical element from the top. It is the graph which plotted the number of the light rays radiate | emitted from the output surface with respect to the position of the y-axis direction of a condensing optical element. It is a conceptual diagram which illustrates the extraction method of the light energy from a condensing optical element.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The perspective view of the external appearance of the photovoltaic device PVS including the condensing device in the embodiment of the present invention is illustrated in FIG. 1, and a conceptual diagram for explaining the principle of the concentrating device 1 included in the photovoltaic device PVS is shown. This is illustrated in 2. In order to clarify the explanation, a coordinate system composed of an x-axis, a y-axis and a z-axis orthogonal to each other is defined, and this is shown in FIG. The z-axis is an axis extending in the thickness direction of the light collecting device 1 in the photovoltaic device PVS, the x-axis is an axis extending in the direction in which light is collected and led out by the light collecting device 1, and the y-axis is these two axes. Is an axis extending in a direction perpendicular to the axis. For convenience of explanation, the orientation shown in FIG. 2 is sometimes referred to as up, down, left, and right. Not limited to.

(Outline of photovoltaic power generation equipment)
An overview of the overall configuration of the photovoltaic power generator PVS will be described. The photovoltaic device PVS includes a condensing device 1 that condenses incident light, a photoelectric conversion element 5 that photoelectrically converts the light that is collected by the condensing device 1 and guided to the end and incident on the end. It is comprised including. The condensing device 1 is formed by a condensing lens 10 that condenses light incident from above, for example, sunlight, and a transparent medium, and is condensed by the condensing lens 10 and enters the inside of the transparent medium. And a condensing optical element 20 that guides incident light. The condensing lens 10 and the condensing optical element 20 are each manufactured using, for example, an inorganic material such as optical glass or a resin material such as PMMA.

In the configuration shown in FIG. 1, a plurality of condenser lenses 10 _ij (10 ₁₁ , 10 ₁₂ ,... 10 _m1 , 10 _m2 ,... 10 _mn ) are arranged in a plurality of rows × a plurality of columns (m rows) in the x-axis direction and the y-axis direction. Xn columns, m and n are natural numbers) are arranged in a matrix and a lens array is formed. The plurality of rows from the first row to the m-th row are arranged in the y-axis direction, and the extending direction of each row of the plurality of rows from the first row to the m-th row is the x-axis direction. The plurality of columns from the first column to the n-th column are arranged in the x-axis direction, and the extending direction of each column of the plurality of columns from the first column to the n-th column is the y-axis direction. In the lens array, a plurality of condensing lenses 10 are integrally formed in a matrix composed of a plurality of rows and a plurality of columns, or individually formed condensing lenses 10 are arranged and fixed in a matrix on a frame or the like. Consists of.

The condensing optical element 20 has a condensing reflection surface that reflects incident light that is collected by the condensing lens 10 and is incident on the condensing optical element 20 due to reflection on the condensing reflection surface. It is configured to be guided in the x-axis direction. FIG. 1 shows a condensing optical system having a plurality of (m rows × n columns) condensing reflection surfaces corresponding to each incident light collected and incident by a plurality of condensing lenses 10 _ij and formed in an integral plate shape. An example of the element 20 is shown. As the photoelectric conversion element 5, various known elements can be used. For example, various types of solar cells composed of the above-described materials such as silicon, compound, organic, and dye sensitization are used. Can be configured.

(Basic configuration of the light collecting device)
FIG. 2 is a schematic diagram for explaining the basic configuration of the condensing device 1. Light collected by the condensing lens 10 _ij and incident on the condensing optical element 20 is reflected in the condensing optical element 20. It is the figure which drawn a mode that it propagates. The basic configuration of the light collecting device 1 refers to the configuration of each of a plurality of structural units included in the light collecting device 1. The structural unit of the condensing device 1 includes a condensing lens 10 _ij and a condensing reflection surface 23 described later.

As shown in FIG. 2A, the condensing optical element 20 includes an upper surface (incident surface) 21 that transmits incident light that is collected by the condensing lens 10 _ij (for example, the condensing lens 10 ₁₁ ), and An optical axis of incident light that extends between the lower surface (back surface) 22 facing the upper surface and extending substantially in parallel and the upper surface 21 and the lower surface 22 and extending in the vertical direction (z-axis direction, thickness direction of the condensing optical element 20). It has a condensing reflection surface (end surface) 23 that intersects with LA, and an exit surface (end surface) 26 that faces the condensing reflection surface 23. The light collected by the condensing lens 10 _ij and incident on the inside of the condensing optical element 20 from the upper surface 21 and reflected by the condensing reflection surface 23 is totally reflected by the upper surface 21 and the lower surface 22 to be in the x-axis direction ( 2 (a) and FIG. 2 (b) to the right) and derived from the exit surface 26. That is, light that propagates inside the condensing optical element 20 and enters the upper surface 21 or the lower surface 22 that is an interface with air from the inside of the condensing optical element 20 is a transparent medium that forms the condensing optical element 20. The light is totally reflected by the difference in refractive index with the air outside the condensing optical element 20.

3 and 4 show how the light collected by the condenser lens 10 _ij and incident on the inside of the condensing optical element 20 propagates inside the condensing optical element 20. It is a figure shown by simulation of trace). FIG. 4 is an enlarged view showing the propagation of light in the vicinity of the condensing reflection surface 23 in FIG. 4A is a view of the vicinity of the condensing reflection surface 23 as viewed in the y-axis direction, and FIG. 4B is a view of the vicinity of the condensing reflection surface 23 as viewed obliquely from below.

As shown in FIG. 4B, the condensing optical element 20 is in contact with the upper surface 21 and the lower surface 22 and connects between the condensing reflection surface 23 and the exit surface 26 and extends substantially parallel to each other. It has a side surface 24 and a side surface 25, and is formed in a square shape in the yz section. The present embodiment will be described using an example in which the condensing reflection surface 23 is a plane.

As shown in FIGS. 3 and 4, the light collected by the condenser lens 10 _ij and incident on the inside of the condenser optical element 20 from the upper surface 21 and reflected by the condenser reflection surface 23 is reflected by the condenser lens 10. _The light spreads in the condensing optical element 20 in a conical shape or a pyramid shape according to the shape of _ij . The light propagating through the condensing optical element 20 is totally reflected on the upper surface 21, the lower surface 22, the side surface 24, and the side surface 25, guided in the x-axis direction, and derived from the output surface 26.

Light collected by the condenser lens 10 _ij and incident from the upper surface 21 and reflected by the condensing reflection surface 23 is totally reflected by the upper surface 21, the lower surface 22, and the side surfaces 24 and 25 of the condensing optical element 20. The condensing optical element 20 is configured to be led out to the emission surface 26. Therefore, the confinement efficiency of the light incident on the inside of the condensing optical element 20 is high, and the condensed light can be led out to the emission surface 26 with high efficiency.

In addition, the condensing optical element 20 is configured such that incident light that is condensed by the condensing lens 10 _ij and incident from the upper surface 21 is also totally reflected by the condensing reflection surface 23. Is condensed by the condenser lens 10 _ij incident from the top surface 21 to the inside of the condensing optical element 20, with respect to the incident light incident on the condensing and reflecting surface 23, the condenser lens 10 _ij passing through the center of the converging lens 10 _ij Incident angle (hereinafter referred to as “optical axis incident angle”) θ _{LA of} light incident on the condensing and reflecting surface 23 along the optical axis LA and a position away from the optical axis LA (outer peripheral portion of the condensing lens 10) The incident angles θ _LA ± θ _{NA of} the light rays that pass through the condensing / reflecting surface 23 are different from each other as shown in FIG. This is because the maximum angle θ _NA with respect to the optical axis LA of the light incident on the condensing reflection surface 23 is not zero. As is clear from FIG. 2 (b), the light is reflected by the converging / reflecting surface 23 toward the end in the traveling direction (the direction away from the condensing / reflecting surface 23), that is, toward the paper surface in FIG. 2 (b). Then, the incident angle of the light beam that enters the condensing / reflecting surface 23 through the outer periphery of the rightmost lens is the minimum incident angle θ _min (= θ _LA −θ _NA ).

In the condensing optical element 20, the minimum incident angle θ _min of the light beam that is collected and incident on the condensing reflection surface 23 is set to be equal to or greater than the total reflection critical angle of the condensing reflection surface 23. Specifically, when the refractive index N of the condensing optical element 20 and the numerical aperture NA (NA = Nsinθ _NA ) of the condensing lens 10 are set to predetermined values, the minimum incident angle θ _min is the entire condensing reflection surface 23. so that the above reflection critical angle, it is possible to set the inclination angle theta ₂₃ relative to the upper surface 21 of the condensing and reflecting surface 23 (lower surface 22). In the example shown in FIG. 2 (b), are mutually parallel to the upper surface 21 and lower surface 22, since the optical axis LA is perpendicular to the top surface 21, the optical axis incident angle theta _LA is equal to the inclination angle theta _23.

The inclination angle theta ₂₃ of refractive index N and condensing and reflecting surface 23 of the converging optical element 20 may be a predetermined value. In that case, the numerical aperture NA of the condenser lens 10 _ij or the focal length f of the condenser lens 10 is set so that the minimum incident angle θ _min is equal to or greater than the total reflection critical angle of the condenser reflecting surface 23. The numerical aperture NA of the condenser lens 10 _ij and the inclination angle θ ₂₃ of the condenser reflecting surface 23 may be set to predetermined values. In that case, the refractive index N of the condensing optical element 20 is set so that the minimum incident angle θ _min is equal to or greater than the total reflection critical angle of the condensing reflection surface 23. Specifically, the refractive index N of the condensing optical element 20 can be set by selecting the material of the condensing optical element 20, the additive to be doped, or the like.

When the entire light totally reflected by the condensing / reflecting surface 23 is incident on the lower surface 22 (and the upper surface 21), the light ray incident on the condensing / reflecting surface 23 at the minimum incident angle and reflected is maximum on the lower surface 22 (and the upper surface 21). A light beam incident at an incident angle and incident on the condensing reflection surface 23 at a maximum incident angle and reflected is incident on the lower surface 22 (and the upper surface 21) at a minimum incident angle. Accordingly, the inclination angle θ _{23 of} the condensing reflection surface 23, the numerical aperture NA of the condensing lens 10 _ij , and / or the refractive index N of the condensing optical element 20 are determined by the condensing reflection surface 23, the upper surface 21, the lower surface 22, and It is set so that the condition of total reflection is satisfied at all the interfaces of the side surfaces 24 and 25.

According to such a configuration, the incident light that has been collected by the condenser lens 10 _{ij and} entered from the upper surface 21 of the condenser optical element 20 enters the condenser optical element 20 and then enters the condenser optical element 20. Are totally reflected at all the interfaces (the condensing reflection surface 23, the upper surface 21, the lower surface 22, and the side surfaces 24 and 25) between the air layer and the air layer. Therefore, the wavelength dependency of the light incident on the condensing optical element 20 is low and the confinement efficiency is high. In this way, the condensed light can be guided to the emission surface 26 with high efficiency.

Further, as shown in each drawing, in the condensing device 1, the condensing lens 10 and the condensing optical element 20 are incident on the condensing optical element 20 after being condensed by the condensing lens _10ij. The light is configured so as to be focused on the surface of the light collecting / reflecting surface 23.

Note that the refractive index of the substance varies depending on the wavelength λ of the transmitted light. Therefore, when the wavelength λ of the light to be collected has a change width, the focal position of the light on the short wavelength side is generally different from the focal position of the light on the long wavelength side. Therefore, the focal position has a change width corresponding to the width of the wavelength band. In the condensing device 1, when the wavelength of incident light is λ = 350 to 1100 nm according to the radiation spectrum of sunlight, a lens with little chromatic aberration is used as the condensing lens 10 _ij , and on the condensing reflection surface 23. The beam spot diameter is set to be minimum.

With such a configuration, the projection area of the condensing reflection surface 23 can be minimized, and therefore the thickness of the condensing optical element 20 can be minimized. When the wavelength band of incident light is narrow or when chromatic aberration can be compensated, the focal position of incident light can be set on the condensing reflection surface 23. Slight defocusing may be performed according to the power density of incident light at the focal position.

The light condensed and incident on the condensing / reflecting surface 23 in this way and totally reflected by the condensing / reflecting surface is totally reflected on each of the upper surface 21, the lower surface 22, the side surface 24, and the side surface 25, thereby collecting optical elements. 20 propagates in the x-axis direction and is derived from the exit surface 26. The emission surface 26 is formed along the yz plane. The end face (outgoing face 26) is polished and AR coated. Therefore, light that has propagated through the condensing optical element 20 and entered the exit surface 26 exits without being reflected by the exit surface 26 and enters the photoelectric conversion element 5.

The basic configuration (configuration of each structural unit) of the light collecting apparatus 1 has been described above. In the above description, the configuration of the condensing / reflecting surface 23 that reflects the light incident on the condensing / reflecting surface 23 by total reflection using the refractive index difference has been described. However, the condensing / reflecting surface 23 may be configured by a mirror on which a metal such as Au, Ag, or Al is deposited, and the mirror may reflect the light incident on the condensing / reflecting surface 23. In this case, the reflection loss in the light converging reflection surface 23 is generated, it is possible to reduce the optical axis incident angle theta _LA (small inclination angle theta ₂₃ of condensing and reflecting surface 23). For example, the optical axis incident angle θ _LA (the inclination angle θ ₂₃ of the condensing reflection surface ₂₃ ) can be set to 45 degrees. A smaller inclination angle theta ₂₃ of condensing and reflecting surface 23, the light reflected by the condensing and reflecting surface 23, top surface 21, bottom surface 22, the minimum incident angle to the side surfaces 24 and the side surface 25 increases. Since the minimum incident angle of the light reflected by the condensing reflection surface 23 to the upper surface 21, the lower surface 22, the side surface 24, and the side surface 25 can be reduced to the critical angle of total reflection, the short focal point having a larger numerical aperture. The condensing lens 10 _ij can be used. If it is possible to use a condenser lens 10 _ij at the short focal, since the distance from the condenser lens 10 _ij to condensing and reflecting surface 23 is reduced, thereby reducing the thickness of the condenser 1. In addition, for the sake of simplicity of explanation, the case where the condensing reflection surface 23 is a flat surface is illustrated, but the condensing reflection surface 23 may be a convex surface or a concave surface having a predetermined shape.

As described above, the light collected by the condenser lens 10 may be sunlight. As shown in FIG. 2 (b), it is more preferable that sunlight is incident on the condenser lens _10ij in parallel with the optical axis LA. Therefore, it is preferable that the condensing device 1 automatically tracks the sun. When condensing sunlight, the condensing device 1 may be configured such that at least light in a specific wavelength range in the sunlight spectrum is condensed. The wavelength range can be determined according to the spectral sensitivity characteristics of the photoelectric conversion element 5. For example, the condensing device 1 can be configured such that light in a wavelength range in which the conversion efficiency of the photoelectric conversion element 5 is not substantially zero is collected. Moreover, you may comprise the condensing apparatus 1 so that the light of the wavelength which becomes the maximum photoelectric conversion efficiency may be condensed.

The specific wavelength range of the light condensed by the condensing lens 10 in the condensing device 1 may be, for example, 350 to 1800 nm, or may be 350 to 1100 nm as described in the present embodiment. There may be. When the wavelength range of the light collected by the condenser lens 10 in the condenser 1 is 350 to 1800 nm, a multi-junction photoelectric conversion element is used as the photoelectric conversion element 5 that photoelectrically converts the collected light. Can be applied. When the wavelength range of the light condensed by the condensing lens 10 in the condensing device 1 is 350 to 1100 nm, a photoelectric conversion element of crystalline silicon is applied as the photoelectric conversion element 5 that photoelectrically converts the collected light. can do.

(Concrete configuration of condensing device)
A specific configuration of the light collecting apparatus 1 will be described with reference to FIGS. 5 and 6 together. FIG. 5A is a side view of the condensing optical element 20, and FIG. 5B is a plan view of the condensing optical element 20. FIG. 6 is a perspective view of one element unit 200 included in the condensing optical element 20 as viewed obliquely from above. 5 and 6, the condensing reflection surface 23 when the condensing optical element 20 is viewed from above is indicated by a solid line.

As described first with reference to FIG. 1, the condensing device 1 is configured to include a plurality of condensing lenses 10 _ij and a plurality of condensing reflection surfaces 23 of m rows × n columns. In other words, the condensing device 1 is configured by providing m rows × n columns of structural units having the basic configuration described with reference to FIGS. 5 and 6, one row × n columns in the condensing optical element 20 is defined as one element unit 200 (201, 202, 203...), And m (m rows) are connected and integrated. The condensing optical element 20 is formed.

FIGS. 5A and 5B are a side view and a plan view of the condensing optical element 20 integrally formed as described above, and FIG. 6 shows one element unit including n condensing reflection surfaces 23. It is the perspective view which looked at 200 from diagonally upward. Each figure illustrates the condensing optical element 20 included in the condensing device 1 when m = n = 10, that is, when the condensing device 1 includes 10 rows × 10 columns of structural units.

In each element unit 200, ten condensing / reflecting surfaces 23 are formed at predetermined intervals along the x-axis. These condensing reflection surfaces 23 are arranged so that the light reflected by each condensing reflection surface does not strike other condensing reflection surfaces, that is, the light reflected by each condensing reflection surface is reflected by the other condensing reflection surfaces. The condensing / reflecting surface 23 and the side surfaces 24 and 25 are formed so as to be slightly inclined from the x-axis (in FIG. 5B, inclined by several degrees) so as not to be blocked. Of the side surfaces 24 and 25, one side surface (the side surface 25 in FIGS. 5 and 6) is formed by one continuous plane, and the other side surface (the side surface 24 in FIGS. 5 and 6) is the condensing reflection surface 23. It is formed in a staircase shape with a gap in between.

That is, ten prismatic unit condensing elements (see FIG. 5A and FIG. 6) having upper and lower surfaces 21, a lower surface 22, a condensing reflection surface 23, a side surface 24, a side surface 25, and an exit surface 26 are arranged in parallel. The element unit 200 (see FIG. 5B) is formed by bundling and removing the side surfaces 24 and 25 that are in contact with each other to share the side surfaces, thereby integrating the 10 unit light collecting elements integrally. The element unit 200 includes n light collecting / reflecting surfaces 23, n side surfaces 24 corresponding to the n light collecting / reflecting surfaces 23, and side surfaces 25 corresponding to the n light collecting / reflecting surfaces 23 in common. It has an upper surface 21, a lower surface 22, and an exit surface 26. The condensing optical element 20 is formed by arranging 10 element units 200 in parallel (10 rows) in an integrated plate shape, and each element unit 200 is a component unit (1 row × 1). This corresponds to a functional element in which 100 unit condensing elements corresponding to one column) are integrated together.

Therefore, the light that is condensed and incident on the condensing / reflecting surface 23 and totally reflected by each condensing / reflecting surface is the upper surface 21, the lower surface 22, the side surface in each element unit 200 (201, 202, 203... 209, 210). In the process of being totally reflected at 24 and the side surface 25 and guided in the x-axis direction, one row of light (10 light fluxes reflected by the 10 condensing reflection surfaces 23) is collected for each element unit 200. Lighted. The light condensed by each element unit 200 is gathered at the junction with the adjacent element unit and is led out from the common emission surface 26. Light derived from the exit surface 26 enters the photoelectric conversion element 5 and is photoelectrically converted.

The size of each condenser lens _{10 ij} and 10 × 10 mm, convergent light converged by the lens array condensing lens _{10 ij} is formed in the size of the aligned and 100 × 100 mm in 10 rows × 10 columns When the light is condensed on the exit surface 26 having a thickness of 1 mm and a width of 100 mm, the light condensing magnification is 100 times.

According to the condensing device 1 having such a configuration, one condensing optical element having one lens array including condensing lenses 10 of m rows × n columns and a condensing reflection surface 23 corresponding thereto. It is possible to provide a light collecting device having a very simple and thin configuration of 20 with almost no loss and high light collecting efficiency. In the conventional light collecting device, there is a problem that the light collecting device becomes complicated because a large number of solar cells are dispersedly arranged at the focal position of a lens or the like, but in the light collecting device 1 in the present embodiment, z Since the photoelectric conversion elements 5 are integrally disposed along the emission surface 26 having a short length in the axial direction (thickness direction of the condensing optical element 20), the condensing device is not complicated. The lens array of the condensing optical element 20 and the condensing lens 10 can be configured by, for example, hot press molding using a low melting point glass or injection molding of a resin such as PMMA. Can be produced.

In the above description, the focused light of 1 row × 10 columns is collected by one element unit 200, and the focused light of 10 rows × 10 columns is collected using 10 element units integrated. Although the optical optical element 20 is illustrated, the configuration of the element unit 200 and the integrated form of a plurality of element units are arbitrary. For example, an exit surface 26 may be provided for each of one or a plurality of element units, and light emitted from each exit surface may be incident on the photoelectric conversion element 5. The element unit may be formed in a star shape according to the arrangement of the condenser lenses. Although the configuration in which the side surface 24 is formed in a step shape is illustrated, the side surface 24 may be formed as a single plane and the side surface 25 may be formed in a step shape. A plurality of condensing reflection surfaces 23 may be formed side by side at predetermined intervals on an axis inclined by several degrees with respect to the x axis, and the side surfaces 24 and 25 may be formed along the x axis.

(Concrete example)
A specific example in which sunlight is condensed by the light collecting device 1 will be described with reference to FIG. 2 and FIGS.

The light condensed by the condensing lens 10 _ij and incident on the condensing optical element 20 from the upper surface 21 is totally reflected at all interfaces of the condensing reflection surface 23, the upper surface 21, the lower surface 22, the side surface 24, and the side surface 25. If the inclination angle theta ₂₃ of condensing and reflecting surface 23 varies according to the numerical aperture NA of the condensing lens 10 _ij. If you set the refractive index N of the converging optical element 20, the tilt angle theta ₂₃ of condensing and reflecting surface 23 is generally varied in accordance with the focal length f of the condenser lens 10 _ij.

Therefore, a simulation in which the condensing lens 10 and the condensing optical element 20 are configured using PMMA (polymethylmethacrylate) and sunlight with a wavelength of 350 nm to 1100 nm is condensed by the condensing lens 10 and the condensing optical element 20. Went. As the refractive index of PMMA, linear interpolation of discrete values described in the table shown in FIG. 7 is used. As the spectral density of the incident light, the one shown in FIG. 8 is used based on the sunlight spectrum. The thickness of the condensing optical element 20 was 1 mm. Under this common condition, the condensing reflection for totally reflecting all the light beams on the condensing reflection surface 23 in the case where the focal length f of the condensing lens 10 is f = 20 mm and in the case where f = 30 mm. the inclination angle theta ₂₃ surface 23 can be calculated as follows.
・ If f = 20 mm, tilt angle θ ₂₃ ≧ 51.2 degrees ・ If f = 30 mm, tilt angle θ ₂₃ ≧ 48.5 degrees

Considering the inclination of the optical axis LA due to the expected angle of the sun, manufacturing errors, etc., the maximum allowable angle of the optical axis LA is larger when the condensing reflection surface 23 is larger, that is, when the inclination angle θ23 of the condensing reflection surface ₂₃ is smaller. This is preferable because the width is increased.

When the angular width of the optical axis LA is ± α, the focal position shift width δx is δx = 2 · f · tan α. X-axis direction length of the condensing and reflecting surface 23 is X = 1 / tanθ _23. Assuming that light rays are collected at one point, when X = δx, the angular width of the optical axis LA is the maximum allowable angular width ± α _max . That is, the shorter the focal length f of the condenser lens 10, the larger the maximum allowable angular width ± _{αmax, which} is preferable. In the above specific example, since it is calculated as follows, it is preferable that the angle width is f = 20 mm.
・ When f = 20 mm, maximum permissible angular width ± α _max = ± 1.15 degrees ・ When f = 30 mm, maximum permissible angular width ± α _max = ± 0.84 degrees

In addition to the above common conditions, the focal length f of the condensing lens 10 is 20 mm and the inclination angle θ ₂₃ of the condensing reflection surface 23 is 52 degrees. From the 10 rows × 10 columns of the condensing lens 10 and the condensing optical element 20 A ray-trace simulation was performed on the condensing device 1. 9 is a ray tracing simulation data at the posture position when the light collecting device 1 is seen from the y-axis direction (side), and FIG. 10 is a ray tracing simulation data at the posture position when the light collecting device 1 is seen obliquely from above. Reference numeral 11 denotes simulation data of ray tracing at a posture position when the condensing optical element 20 is viewed from the z-axis direction (above).

From the simulation data shown in these drawings, the light rays collected and incident on the plurality of condensing reflection surfaces 23 included in each of the plurality of element units 200 (201, 202, 203... 209, 210) The light density increases as it is totally reflected by the upper surface 21, the lower surface 22, the side surface 24, and the side surface 25 and guided in the x-axis direction and reaches the base end side (exit surface 26 side) of the plurality of element units 200. I understand that. That is, in FIGS. 9, 10, and 11, the number of light rays is small at a position away from the emission surface 26 in the x-axis direction, and the number of light rays is large near the emission surface 26. In FIG. 11, the light beam that appears to be emitted (leaked) from the condensing optical element 20 is not leaked to the outside, but rather the light from the outside is condensed and reflected by the condensing lens 10. It is a light beam indicating that the light is condensed and incident on the light source 23. According to FIG. 11, the light beam reflected inside the condensing optical element 20 by the condensing reflection surface 23 hardly leaks from the condensing optical element 20 and is led out from the emission surface 26. Understood.

FIG. 12 shows the light beam emitted from the exit surface relative to the position of the condensing optical element 20 in the y-axis direction, where the horizontal axis represents the position of the condensing optical element 20 in the y-axis direction and the vertical axis represents the number of light beams emitted from the exit surface 26. It is the graph which plotted the number of. From this graph, in the

individual element units

201, 202, 203... 209, 210, the light distribution in the y-axis direction of the light collected in units is uniform, and in the entire light collecting optical element 20, It can be seen that the light distribution of the light emitted from the emission surface 26 is uniform. The fact that the light distribution of the light emitted from the emission surface 26 is uniform means that the distribution of the number of rays of the emitted light is uniform within the surface of the emission surface 26. The intensity distribution of the emitted light at is uniform.

The analysis results by this simulation are summarized based on numerical values as follows. If the angular width of the optical axis LA is zero, a completely parallel light beam has arrived at the condenser lens 10 _ij . When the sunlight composed of the completely parallel light flux is condensed by the condenser lens 10 _ij and incident on the condensing optical element 20, the sunlight exits from the exit surface 26 when the total amount of sunlight is 100. The total amount of light emitted is 99.7, and the light collection efficiency is 99.7%. When the angle width of the optical axis LA is ± 0.5 degrees, that is, when light arrives at the condenser lens 10 _ij with a uniform incident angle distribution having a width of 0.5 degrees around the optical axis LA, The total amount of light emitted from the emission surface 26 is 99.5 with respect to the total light amount 100 of sunlight when entering the optical optical element 20, and the light collection efficiency is 99.5%. From this simulation result, it was confirmed that according to the condensing device 1, sunlight can be condensed with extremely high condensing efficiency.

(Extraction method of light energy at the end of the condensing optical element)
In the condensing device 1 described above, examples of the concept of some typical methods are illustrated for the method of extracting the energy of the light that is condensed by the condensing lens 10 and the condensing optical element 20 and is emitted from the exit surface 26. A brief description will be given with reference to FIGS. 13 (a) to 13 (e).

FIG. 13A is a conceptual diagram of a configuration example for taking out the light collected at the end of the condensing optical element 20 as it is from the emission surface 26 and using it as light. In FIG. 13A, the light emitted from the emission surface 26 of the condensing optical element 20 is condensed through a cylindrical lens 91, a condensing rod 92, and the like, and the condensed light is brought to a desired position by an optical fiber 93. The structure which guides light is illustrated.

FIG. 13B is a conceptual diagram of one configuration example for using the light collected at the end of the condensing optical element 20 by converting it into electric energy or heat energy. FIG. 13B shows a configuration example in which the photoelectric conversion element 5 is coupled to the emission surface 26 of the condensing optical element 20 and the energy of the collected light is extracted as electric energy through photoelectric conversion by the photoelectric conversion element 5. Show. In this way, a photovoltaic device including the condensing device 1 and the photoelectric conversion element 5 is obtained. Instead of the photoelectric conversion element 5, a condensing device 1 and the photothermal conversion element are included by coupling a photothermal conversion element that extracts the energy of the collected light as heat energy to the emission surface 26 of the condensing optical element 20. A photothermal conversion device is obtained. It is preferable to use a heat pipe with a light absorber or the like as a light-to-heat conversion element that converts the collected light into heat energy.

FIG. 13C is a conceptual diagram of one configuration example for using the light collected at the end of the condensing optical element 20 by converting it into electric energy or heat energy. In FIG. 13C, a mirror 94 is disposed on the exit surface 26 obtained by cutting the end of the condensing optical element 20 obliquely with respect to the upper surface 21 and the lower surface 22 (or a reflective film on the exit surface 26). It is a figure which shows an example of the structure obtained by forming. As shown in FIG. 13C, the light condensed on the end of the condensing optical element 20 is collected on the photoelectric conversion element 5 provided on the upper surface 21 side (or lower surface 22 side) of the condensing optical element 20. Light up. Thereby, even if the condensing optical element 20 is a thin sheet form, the photoelectric conversion element 5 which occupies a predetermined area can be attached stably. In this way, a photovoltaic device including the condensing device 1 and the photoelectric conversion element 5 is obtained. When taking out the energy of the condensed light as thermal energy, it is preferable to use a heat pipe with a light absorber instead of the photoelectric conversion element 5 as described above. Thus, a photothermal conversion device including the light collecting device 1 and the photothermal conversion element is obtained.

FIG. 13D is a conceptual diagram of one configuration example for converting the energy of the light collected at the end of the condensing optical element 20 into electric energy or heat energy. In FIG. 13D, a dichroic mirror 95 is disposed on the exit surface 26 obtained by cutting the end of the condensing optical element 20 obliquely with respect to the upper surface 21 and the lower surface 22 (or the wavelength on the exit surface 26). It is a figure which shows an example of the structure obtained by forming a reflective film with selectivity. As shown in FIG. 13D, a photoelectric conversion element provided on the upper surface 21 side (or lower surface 22 side) of the condensing optical element 20 by dividing the light collected at the end of the condensing optical element 20. The light is condensed on 5a and the photoelectric conversion element 5b provided on the side of the condensing optical element 20, respectively. According to such a configuration, since a highly efficient photoelectric conversion element can be used as the

photoelectric conversion elements

5a and 5b according to each wavelength band of the divided light, the light collecting device 1 and the

photoelectric conversion elements

5a and 5b are used. And a photovoltaic device with high conversion efficiency at a relatively low cost.

One of the divided light (for example, light in the infrared region) is incident on a heat pipe with a light absorber and the thermal energy obtained by photothermal conversion is used, and the other of the divided light (for example, visible region) In addition, a configuration in which light in the ultraviolet region) is incident on the photoelectric conversion element 5 and electric energy obtained by photoelectric conversion is used is also an example of a preferable configuration.

FIG. 13E shows that the light collected at the end of the condensing optical element 20 is further thinned in the thickness direction of the condensing optical element 20 (in the optical axis direction of the condensing lens 10 _ij ). It is a conceptual diagram of one structural example for condensing and taking out. In FIG. 13 (e), the condensing optical element 20 is formed in a parabolic shape in which the thickness of the condensing optical element 20 gradually decreases toward the exit surface 26 in the vicinity of the exit surface 26. Therefore, the light traveling in the x-axis direction inside the condensing optical element 20 is totally reflected by the upper surface 21 or the lower surface 22, and is in the thickness direction of the condensing optical element 20 (the optical axis direction of the condensing lens _10ij ). It is narrowed and condensed. Accordingly, for example, when the collected light is used as it is, it can be configured without using a cylindrical lens or the like, and when the collected light is incident on the photoelectric conversion element 5 or the heat pipe, it is simple. With the configuration, the power density of incident light can be increased.

As described above, in the condensing device 1, incident light that is condensed by the condensing lens 10 and enters the condensing optical element 20 from the upper surface 21 of the condensing optical element 20 is collected. After entering the inside 20, the light is totally reflected by all the interfaces (the condensing reflection surface 23, the upper surface 21, the lower surface 22, and the side surfaces 24 and 25) except the exit surface 26, and exits from the exit surface 26. Therefore, according to the condensing apparatus 1 demonstrated above, the new condensing apparatus which can use optical energy, such as sunlight efficiently, can be provided with a comparatively thin and simple structure. The photovoltaic device PVS and the photothermal conversion device including such a condensing device 1 have a small thickness in the optical axis direction, are small and lightweight, and are suitable as a new photovoltaic power generation device or a solar heat collecting device. Can be applied.

Although various embodiments and modifications have been described above, the present invention is not limited to these contents. Other embodiments conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention.

The disclosure of the following priority application is hereby incorporated by reference.
Japanese Patent Application No. 2010 189386 (filed on Aug. 26, 2010)

Claims

A condenser lens;
An incident surface on which light collected by the condensing lens is incident, a back surface facing the incident surface, and a first end surface intersecting the optical axis of the condensing lens between the incident surface and the back surface; A condensing optical element having a second end surface facing the first end surface between the incident surface and the back surface, and formed of a transparent medium,
The first end surface reflects the light incident on the condensing optical element from the incident surface;
The incident surface and the back surface totally reflect the light reflected by the first end surface,
The condensing device in which the light reflected by the first end face, the light totally reflected by the incident face, and the light totally reflected by the back face enter the second end face.
The light collecting device according to claim 1,
The minimum incident angle of light included in the light incident on the first end surface from the incident surface into the condensing optical element is equal to or greater than the total reflection critical angle on the first end surface. A condensing device in which an inclination angle of the first end surface with respect to the incident surface is set.
In the condensing device according to claim 1 or 2,
The minimum incident angle of light included in the light incident on the first end surface from the incident surface into the condensing optical element is equal to or greater than the total reflection critical angle on the first end surface. A condensing device in which the numerical aperture of the condensing lens is set.
The light collecting device according to any one of claims 1 to 3,
The minimum incident angle of light included in the light incident on the first end surface from the incident surface into the condensing optical element is equal to or greater than the total reflection critical angle on the first end surface. A condensing device in which the refractive index of the condensing optical element is set.
The light collecting device according to any one of claims 1 to 4,
The condensing lens and the condensing optical element are arranged so that the light entering the condensing optical element from the incident surface and entering the first end surface is focused on the first end surface. Concentrator.
The light collecting device according to any one of claims 1 to 5,
The condensing optical element has a first side surface and a second side surface that are in contact with the incident surface and the back surface and face each other between the first end surface and the second end surface;
The first side surface and the second side surface totally reflect the light reflected by the first end surface, the incident surface, and the back surface,
The light reflected by the first end surface, the light totally reflected by the incident surface, the light totally reflected by the back surface, the light totally reflected by the first side surface, and the light reflected by the second side surface. The reflected light is a light collecting device that enters the second end face.
The light collecting device according to any one of claims 1 to 6,
A plurality of condenser lenses, each of which is the condenser lens, are arranged,
The condensing optical element has a plurality of first end surfaces, each of which is the first end surface, and is integrally formed.
The light collecting device according to claim 6,
A plurality of condenser lenses, each of which is the condenser lens, are arranged,
The condensing optical element includes a plurality of first end surfaces, each of which is the first end surface, a plurality of first side surfaces corresponding to the plurality of first end surfaces in common, and a plurality of each of which is the second side surface. A light collecting device having a second side surface and integrally formed.
The light collecting device according to claim 7 or 8,
The plurality of condenser lenses are arranged in a matrix composed of a plurality of rows and a plurality of columns,
The condensing optical element includes the plurality of first end surfaces, the first side surface, and the plurality of second side surfaces corresponding to the condensing lenses of each row of the plurality of condensing lenses. And a light collecting device that is integrally molded corresponding to the plurality of rows.
The light collecting device according to claim 9,
The light reflected by each of the plurality of first end faces is inclined with respect to the extending direction of each row so as not to be blocked by another first end face of the plurality of first end faces. Optical device.
The light collecting device according to any one of claims 1 to 10,
A condensing device in which a distance between the first end surface and the second end surface is sufficiently larger than a distance between the incident surface and the back surface.
The light collecting device according to any one of claims 1 to 11,
The light incident on the incident surface is a condensing device that is obtained when the condenser lens condenses sunlight.
The light collecting device according to any one of claims 1 to 12,
The condensing device in which the incident surface and the back surface are substantially parallel to each other.
The light collecting device according to any one of claims 1 to 13,
A photovoltaic device comprising: a photoelectric conversion element that photoelectrically converts the light incident on the second end face.
The light collecting device according to any one of claims 1 to 13,
A photothermal conversion device comprising: a photothermal conversion element for photothermal conversion of the light incident on the second end face.