WO2019004325A1

WO2019004325A1 - Lens array and method for manufacturing lens array

Info

Publication number: WO2019004325A1
Application number: PCT/JP2018/024470
Authority: WO
Inventors: 綾　洋一郎
Original assignee: パナソニック株式会社
Priority date: 2017-06-29
Filing date: 2018-06-27
Publication date: 2019-01-03

Abstract

A lens array (20) according to the present disclosure includes a plurality of lenses (21), each of which collects sunlight. The lens array (20) includes a light incident surface (21a) whereon sunlight is incident, and a light emission surface (21b) located opposite the light incident surface (21a) and emitting the sunlight entering through the light emission surface (21a). The light incident surface (21a) has a recess (22) that is recessed toward the light emission surface (21b) across the plurality of lenses (21).

Description

Lens array and method of manufacturing lens array

The present disclosure relates to a lens array in which a plurality of lenses, each of which condenses sunlight, is arranged, and a method of manufacturing the lens array.

Conventionally, development of a solar cell module has been advanced as a photoelectric conversion device that converts light energy into electric energy. Solar cell modules are expected as new energy sources because they can convert inexhaustible sunlight directly into electricity, and because they have less environmental impact and are cleaner than fossil fuel power generation.

BACKGROUND ART In recent years, a concentrating solar cell module with a small amount of use of solar cells (power generation element) has attracted attention. In the concentrating solar cell module, the sunlight collected by the condensing lens (lens array) is incident on the solar cell.

Patent Document 1 discloses a solar cell module having high conversion efficiency (power generation efficiency) by curving the light receiving surface of the solar cell in a concave shape and reducing the reflection of light on the surface of the solar cell. There is.

JP 2007-48910 A

By the way, the light incident surface on which the sunlight of the condenser lens is incident is exposed to the atmosphere, and dust such as dust adheres thereto. When dust adheres to the light incident surface, the sunlight incident on the condenser lens decreases, leading to a reduction in conversion efficiency. In the solar cell module described in Patent Document 1, the light incident surface is a flat surface, and this flatness is considered to wash away (clean) dust attached to the light incident surface due to rain or the like.

However, in the solar cell module described in Patent Document 1, since the cleaning effect does not appear unless it rains, improvement of the cleaning effect is desired.

Then, this indication aims at providing the manufacturing method of the lens array by which the cleaning effect was improved rather than before, and the lens array concerned.

In order to achieve the above object, a lens array according to an aspect of the present disclosure is a lens array in which a plurality of lenses are arranged in an array, and each of the plurality of lenses condenses sunlight. The lens array has a light incident surface on which sunlight is incident, and a light emitting surface located on the opposite side of the light incident surface and from which the sunlight incident on the light incident surface is emitted. The light incident surface is formed with a concave portion recessed on the light emitting surface side across a plurality of lenses.

Further, in order to achieve the above object, according to a method of manufacturing a lens array according to an aspect of the present disclosure, a plurality of lenses are arranged in an array, and each of the plurality of lenses collects sunlight. It is a method. The lens array manufacturing method includes an injection step of filling the molten resin into the mold, and a cooling step of cooling the filled resin, and in the cooling step, the lens is cooled by controlling the cooling rate of the mold. A recessed portion is formed across a plurality of lenses in a light incident surface of the array on which the sunlight is incident.

According to the present disclosure, it is possible to provide a lens array in which the cleaning effect is improved as compared to the prior art.

FIG. 1: is a schematic diagram which shows the external appearance of the solar cell module which concerns on embodiment. FIG. 2 is a schematic cross-sectional view of the solar cell module according to the embodiment, taken along line 2-2 of FIG. FIG. 3 is a schematic cross-sectional view of the first lens array according to the embodiment. FIG. 4 is an example of a measurement result showing the shape of the first lens array according to the embodiment. FIG. 5 is a view for explaining the dust removal by the recess of the first lens array according to the embodiment. FIG. 6 is a flowchart showing a method of manufacturing the first lens array according to the embodiment.

Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, the detailed description may be omitted if necessary. For example, detailed description of already well-known matters and redundant description of substantially the same configuration may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art.

It is to be noted that the inventors provide the attached drawings and the following description so that those skilled in the art can fully understand the present disclosure, and intend to limit the subject matter described in the claims by these. Absent.

Further, each drawing is a schematic view, and is not necessarily illustrated exactly. Further, in the drawings, substantially the same configurations are denoted by the same reference numerals, and overlapping descriptions may be omitted or simplified.

Further, in the drawings used for the description in the following embodiments, coordinate axes may be shown. The minus side of the Z axis represents the mounting surface side of the solar cell module, and the plus side of the Z axis represents the light incident surface side of sunlight. The X axis and the Y axis are axes orthogonal to each other on a plane perpendicular to the Z axis. For example, in the following embodiment, “plan view” means viewing from the light incident surface side (viewing from the Z-axis direction). Also, for example, in the following embodiment, “cross-sectional view” means that the solar cell module cut at a plane including the cutting line is viewed from the side perpendicular to the plane cut. For example, when the solar cell module is cut along a plane defined by the Y axis and the Z axis (an example of a plane cut by a cutting line), cross sectional view means that the cross section is viewed from the X axis direction side doing.

Further, in the present specification, the term indicating the relationship between elements such as orthogonal, the term indicating the shape of an element such as a square, and the expression “abbreviation” are not expressions expressing only a strict meaning, The expression is meant to include substantially the same range, for example, a difference of several percent.

Embodiment
Hereinafter, a solar cell module 10 including the first lens array 20 according to the present embodiment will be described with reference to FIGS. 1 to 6.

[1. Overall configuration of solar cell module]
First, the configuration of a solar cell module 10 according to the present embodiment will be described with reference to FIGS. 1 to 4.

FIG. 1 is a schematic view of a solar cell module 10 according to the present embodiment. The solar cell module 10 is a concentrating solar cell module that condenses sunlight by a lens (optical system).

FIG. 2 is a schematic cross-sectional view of the solar cell module 10 according to the present embodiment, taken along line 2-2 of FIG. The solar cell module 10 includes a first lens array 20, a second lens array 30, a resin plate 40 which is one of holding members, a power generation element 50, and an electrode 60. Line 2-2 in FIG. 1 is a cutting line which is parallel to the Y-axis direction and cuts the center of the solar cell module 10 in the X-axis direction.

[1-1. First lens array]
First, the first lens array 20 will be described with reference to FIGS. 1 to 4.

As shown in FIG. 1, the first lens array 20 is a primary condensing lens array configured by arranging a plurality of first lenses 21 having a positive refractive index in an array (two-dimensional). . The first lens 21 condenses sunlight on a second lens 31 of a second lens array 30 described later. The first lens array 20 is an example of a lens array, and the first lens 21 is an example of a lens. The first lens array 20 may be configured by arranging the first lenses 21 in a one-dimensional manner as one form of an array.

In the present embodiment, the first lens array 20 is configured by arranging the 25 first lenses 21 in an array, but the number of the first lenses 21 constituting the first lens array 20 Is not particularly limited. Moreover, the shape in planar view of the 1st lens 21 is not specifically limited. Although FIG. 1 shows an example in which the shape of the first lens 21 is square, the first lens 21 may be rectangular or hexagonal.

In the present embodiment, the first lens 21 has a square shape with a side of 22 mm. That is, the first lens array 20 has a square shape with one side of 110 mm. The thickness (length in the Z-axis direction) of the first lens 21 is, for example, 7.5 mm or more and 10 mm or less. Note that one side of the first lens may be smaller than 22 mm, and for example, may be 10 mm or more and 20 mm or less.

As shown in FIG. 2, the first lens array 20 is a light incident surface 21a (surface on the Z axis plus side) on which sunlight is incident and a surface on the opposite side to the light incident surface 21a, and the sunlight is It has the light emission surface 21b (surface by the side of Z-axis minus) to radiate | emit. Further, in the present embodiment, as each of the first lenses 21, for example, a convex lens in which the convex portion 24 is formed on the light emitting surface 21 b side is used. For example, in each of the plurality of first lenses 21, the convex portion 24 is formed so as to protrude in a direction in which sunlight is emitted (a direction from the Z-axis plus side to the Z-axis minus side). That is, the first lens array 20 has a convex shape that protrudes on the second lens array 30 side for each first lens 21.

The light incident surface 21a is recessed toward the light emission surface 21b. The first lens array 20 according to the present embodiment is characterized in that the recess is formed. Below, the dent currently formed in the ight-incidence surface 21a is demonstrated.

FIG. 3 is a schematic cross-sectional view of the first lens array 20 according to the present embodiment, and specifically, only the first lens array 20 in the schematic cross-sectional view of the solar cell module 10 shown in FIG. It is the cross-sectional schematic diagram which showed. In addition, in FIG. 3, in order to demonstrate the recessed part 22 and the separate recessed part 23, the 1st lens array 20 shown in FIG. For example, in FIG. 3, the scale in the thickness direction (Z-axis direction) of the first lens array 20 is shown exaggeratingly more than the first lens array 20 shown in FIG. 2.

As shown in FIG. 3, the light incident surface 21 a has a recess 22 and an individual recess 23. The two-dot chain line in FIG. 3 is a straight line connecting outer edges forming the outer shape of the first lens array 20 in a plan view, and is a straight line parallel to the Y axis. Moreover, the broken line in FIG. 3 has shown the external shape of the recessed part 22. FIG. The broken line is formed, for example, by connecting the outer edge and the boundary portion of the adjacent first lenses 21. That is, the area surrounded by the dashed-two dotted line and the broken line is the recess 22.

The recess 22 is a recess formed over the plurality of first lenses 21. In FIG. 3, the recess 22 is formed across the five first lenses 21. For example, the depth (the length in the Z-axis direction) of the concave portion 22 increases as it goes from the outer edge of the first lens array 20 to the center in a plan view of the first lens array 20. That is, the concave portion 22 is formed over the entire 25 first lenses 21 constituting the first lens array 20, and the depth is maximized at the center of the first lens array 20 in plan view. . The maximum depth may be a depth that does not disturb the focusing characteristics of the first lens array 20 (in other words, does not substantially affect the focusing characteristics). For example, the maximum depth of the recess 22 is 20 μm or less.

The maximum depth of the recess 22 is the distance from the two-dotted chain line in FIG. 3 to the position of the recess 22 farthest away from the two-dot chain line (see depth L1 in FIG. 3).

The shape of the recess 22 is arc-shaped in a cross-sectional view when viewed from a direction orthogonal to the direction (for example, the Z-axis direction) in which sunlight is incident. Further, FIG. 3 shows a schematic cross-sectional view of the solar cell module 10 shown in FIG. 1 cut along a plane (YZ plane) parallel to the Z-axis including the line 2-2. A schematic cross-sectional view cut along a plane (XZ plane) parallel to the Z-axis including a cutting line (cutting line extending in the X-axis direction) orthogonal to the 2-2 line also has the shape shown in FIG. That is, the outer shape of the recess 22 is arc-shaped. That is, the recess 22 is a dome-shaped recess.

Next, the individual recesses 23 will be described. The individual recess 23 is a recess formed from the recess 22 toward the light emitting surface 21 b side (in other words, the protrusion 24 side) for each of the plurality of first lenses 21.

The individual recess 23 is a recess formed on the protrusion 24 of the first lens 21 in one-to-one correspondence. In the present embodiment, since one convex portion 24 is formed in each of the plurality of first lenses 21, the individual concave portions 23 are formed in one-to-one correspondence with each of the plurality of first lenses 21. For example, in the plan view of the first lens array 20, the depth of the individual recesses 23 increases toward the center of the first lens 21 (in other words, the center of the projection 24 in plan view). That is, the depth of the individual recess 23 is maximum at the center of the first lens 21. The maximum depth may be a depth that does not disturb the focusing characteristic of the first lens array 20. More specifically, the maximum depth of the individual recesses 23 is such a depth that does not disturb the light collection characteristic of the first lens array 20 at the total depth of the depths of the recesses 22 and the individual recesses 23. It is good. For example, the maximum depth of the individual recesses 23 is 10 μm or less.

The maximum depth of the individual recess 23 is a distance from the broken line to the position of the individual recess 23 which is most distant from the broken line (see depth L2 in FIG. 3).

The shape of the individual recess 23 is arc-shaped in a cross-sectional view when viewed from the direction orthogonal to the direction in which the sunlight is incident. Further, FIG. 3 shows a schematic cross-sectional view of the solar cell module 10 shown in FIG. 1 cut along a plane (YZ plane) parallel to the Z-axis including the line 2-2. A schematic cross-sectional view cut along a plane (XZ plane) parallel to the Z-axis including a cutting line (cutting line extending in the X-axis direction) orthogonal to the 2-2 line also has the shape shown in FIG. That is, the outer shape of the individual recess 23 is arc-shaped. That is, the individual recess 23 is a dome-shaped recess.

Here, the measurement results of the concave portions 22 and the individual concave portions 23 of the manufactured first lens array 20 will be described with reference to FIG.

FIG. 4 is an example of a measurement result showing the shape of the first lens array 20 according to the present embodiment. More specifically, it is a measurement result indicating the shape of the light incident surface 21 a of the first lens array 20, that is, the shapes of the recess 22 and the individual recess 23. In FIG. 4, the horizontal axis indicates the measured position of the first lens array 20 in the Y-axis direction. That is, the length of the first lens array 20 measured is about 111400 μm (about 111 mm). The vertical axis indicates the position of the first lens array 20 in the Z-axis direction.

As shown by the broken line in FIG. 4, it can be seen that the recess 22 and the five individual recesses 23 are formed in the first lens array 20. Further, the maximum value of the sum of the depth of the recess 22 and the depth of the individual recess 23 is 18.90 μm, and the maximum depth of the recess 22 is about 10 μm. Further, the position of maximum depth is approximately 58000 μm (approximately 58 mm), and is located approximately at the center in a cross sectional view.

The material of the first lens array 20 may be a transparent resin. It is for contributing to weight reduction of the solar cell module 10. Specifically, the first lens array 20 is manufactured by injection molding acrylic resin (PMMA) or the like. The method of manufacturing the first lens array 20 will be described later.

[1-2. Second lens array]
Next, the second lens array 30 will be described with reference to FIG.

In the second lens array 30, a plurality of second lenses 31 having a convex shape protruding from the power generation element 50 side to the first lens 21 side (Z-axis negative side to Z-axis positive side) are arranged in an array. The secondary condensing lens array configured as described above is disposed on the light emission direction side of the first lens array 20. Further, the second lens array 30 includes a base portion 32 as a support substrate extending in the XY plane in FIG. 2 and a second portion formed on the light incident surface side (Z-axis plus side) of the base portion 32. And a lens 31. The optical axis of the second lens 31 coincides with the optical axis of the first lens 21. Note that "matching" is not limited to the case of perfect matching, but includes substantially matching. For example, even if the two values have a few percent error, they can be considered to match.

The base portion 32 has a plate shape, and the second lenses 31 are arranged in an array on the surface of the base portion 32 in one-to-one correspondence with the first lenses 21 of the first lens array 20. Further, the second lens 31 and the base portion 32 are integrally molded.

The material of the second lens array 30 may be transparent resin. It is for contributing to weight reduction of the solar cell module 10 by using resin. Specifically, the second lens array 30 is manufactured by extrusion molding or injection molding of an acrylic resin. The first lens array 20 and the second lens array 30 may be formed of the same material.

[1-3. Power generation module]
Next, a power generation module including the power generation element 50 that performs photoelectric conversion and the holding member that holds the power generation element 50 will be described with reference to FIG. In the present embodiment, the holding member is described as a transparent resin plate 40 made of acrylic resin, but the material and shape of the holding member are not particularly limited, and glass (including transparent amorphous) Or transparent crystals may be used.

The resin plate 40 is an example of a holding member for holding the power generation element 50, and is, for example, a flat member. The resin plate 40 is fixed to the base 32 (for example, a recess formed in the base 32) of the second lens array 30 by an adhesive of silicone resin.

The power generation element 50 mounted on the resin plate 40 may be aligned with the focal point of the second lens 31 when disposed on the base portion 32 of the second lens array 30. For example, a concave portion for aligning the resin plate 40 is formed in the base portion 32, and when the resin plate 40 is inserted into the concave portion, the position of the focal point of the second lens 31 and the position of the power generating element 50; Should match. When the recess is formed in the base portion 32, the power generating element 50 can be disposed at the focal point of the second lens 31 simply by inserting the resin plate 40 in which the power generating element 50 is fixed in the recess. Process can be shortened. That is, the power generation element 50 is disposed on the focal position of the second lens 31 and the optical axis (which substantially coincides with the optical axis of the first lens 21) by the positioning concave portion formed in the base portion 32. , And at equal intervals along the X-axis direction and the Y-axis direction.

The holding member is formed of a transparent material. Thereby, even when the power generation element 50 is fixed to the surface (surface on the Z axis minus side) opposite to the second lens array 30 of the resin plate 40, the power generation element 50 is condensed. It can receive sunlight.

The distance between the first lens array 20 and the power generation element 50 is determined by the focusing characteristics of the first lens array 20 and the second lens array 30, but is about 31 mm as an example.

The power generation element 50 has a function of converting the light energy of the emitted sunlight into electric energy. The power generation element 50 is composed of a thin film of a GaAs-based material, a GaN-based material, and a Si-based material. When light is irradiated to these thin films, a photocurrent is generated, so that it is possible to supply an electrical energy to an external circuit (not shown). For the power generation element 50, it is preferable to use a thin film made of a GaAs-based material having an energy conversion efficiency of 40% or more. The light receiving area of the power generation element 50 is, for example, approximately 1 mm ² .

An electrode 60 for extracting the photocurrent generated in the power generation element 50 to an external circuit is formed on the light emitting surface side (Z axis minus side) of the second lens array 30. As the electrode 60, for example, a Cu foil, an Al foil, or a Ni foil can be used.

In the solar cell module 10, a printed board (including a flexible board) on which the power generation element 50 and the electrode 60 are mounted by surface mounting is combined with the first lens array 20 and the second lens array 30. It may be manufactured by

[1-4. Outer frame etc]
Next, members such as an outer frame will be described with reference to FIG.

An outer frame 70 and a support member 71 are disposed between the first lens array 20 and the second lens array 30. The support member 71 supports the first lens array 20 with respect to the second lens array 30, and maintains the distance between the first lens array 20 and the second lens array 30. In the case of the present embodiment, the outer frame 70 and the support member 71 are each integrally formed with the second lens array 30. The support member 71 includes a support portion 71a and a tip portion 71b. The outer frame 70 and the tip end portion 71 b of the support member 71 are in contact with the light emitting surface 21 b of the first lens array 20 to support the first lens array 20. The portion of the tip portion 71 b in contact with the first lens array 20 is, for example, substantially spherical. The width (thickness) of the tip portion 71b on the first lens array 20 side with respect to the width (thickness) of the support member 71 is thin (thin). Thereby, interference of the support member 71 with the sunlight emitted from the first lens 21 can be suppressed.

The solar cell module 10 configured as described above is lightweight because the first lens array 20, the second lens array 30, and the resin plate 40 are made of acrylic resin. For example, the solar cell module 10 directs the sunlight to direct the light incident surface 21a of the solar cell module 10 to the sunlight side regardless of the time (in other words, to make the sunlight incident vertically on the light incident surface 21a) It may be mounted and used in a tracking device (not shown). Specifically, a plurality of solar cell modules 10 may be mounted and used in an apparatus for tracking sunlight. Thereby, it is possible to receive sunlight perpendicular to the light incident surface 21a in many hours of the day.

In this case, since the solar cell module 10 is lightweight, the intensity required for the device for tracking sunlight can be reduced. That is, with the solar cell module 10 according to the present embodiment, the cost of incidental equipment such as a device for tracking sunlight can be reduced. Furthermore, the apparatus for tracking sunlight is a solar cell module with less energy than when the first lens array, the second lens array, and the resin plate are formed of a material heavier than acrylic resin such as glass. The ten light incident surfaces 21a can be moved toward sunlight. That is, the power generation efficiency of the solar cell module 10 can be improved with less energy.

[2. State of dust removal]
Subsequently, dust removal of the solar cell module 10 including the first lens array 20 described above will be described with reference to FIG.

FIG. 5 is a view for explaining the dust removal by the recess of the first lens array 20 according to the present embodiment. The straight arrows in FIG. 5 indicate the flow (air flow) of the wind 80. FIG. 5 shows an example in which the wind 80 is blowing in a direction parallel to the Y-axis direction with respect to the light incident surface 21a of the first lens array 20 as an example. The dust 90 is an object that prevents sunlight from being incident on the light incident surface 21a, and is, for example, dust.

As shown in FIG. 5, when the wind 80 blows, the wind 80 is disturbed by the depressions (specifically, the concave portions 22 and the individual concave portions 23) formed on the light incident surface 21a of the first lens array 20. , The flow of wind 81 is formed. Specifically, the wind 81 is a flow of wind toward the light incident surface 21a (flow of wind from the Z-axis plus side to the Z-axis negative side) and a flow of wind toward the direction away from the light incident surface 21a (Z It is formed from the flow of the wind which goes to the Z-axis plus side from the axis minus side). By the flow of the wind 81, the dust 90 attached to the light incident surface 21a is removed. In order to exhibit such a dust removal effect, it is necessary for the first lens array 20 to have at least a recess 22 for disturbing the wind 80, and the maximum depth of the recess 22 is 5 μm or more. It is desirable to have. Furthermore, the effect of dust removal is improved by forming the individual recesses 23.

In addition, since the conventional first lens array has a flat light incident surface, the disturbed wind as shown in FIG. 5 does not occur even when the wind is blown. That is, in the conventional first lens array, the cleaning effect of dust by wind was low.

Furthermore, the first lens array 20 according to the present embodiment is also effective for floating dust 91. Specifically, when the floating dust 91 falls toward the light incident surface 21a, the wind 81 is generated so that the dust 91 is blown off before it adheres to the light incident surface 21a. Can. That is, with the first lens array 20 according to the present embodiment, adhesion of the dust 91 to the light incident surface 21a can be suppressed.

The light incident surface of the first lens array is cleaned by rain or the like. For example, when dust such as dust is attached to the light incident surface, the attached dust is washed away by water droplets such as rain. In the first lens array 20 according to the present embodiment, the depth of the concave portions 22 and the individual concave portions 23 formed is as small as 20 μm or less and 10 μm or less, while suppressing the influence on the cleaning effect due to rain or the like. The cleaning effect of the wind 80 can be enhanced.

From the viewpoint of removing the dust 90 attached to the light incident surface 21a, the recess should be large.

[3. Method of Manufacturing First Lens Array]
Next, a method of manufacturing the above-described first lens array 20 will be described with reference to FIG.

FIG. 6 is a flowchart showing a method of manufacturing the first lens array 20 according to the present embodiment. Below, the method to manufacture the 1st lens array 20 by injection molding is demonstrated.

First, a heating step of heating a mold used for injection molding is performed (S10). For example, the mold is attached to an injection molding machine and heated by a heater or the like of the injection molding machine. The temperature of the heated mold is appropriately determined depending on the resin material and the like used, and is about 300 ° C. as an example.

Next, an injection step of filling the molten resin (hereinafter also referred to as molten resin) in a mold is performed (S20). That is, the molten resin is injected into the heated cavity space of the mold. The melted resin is a resin material for forming the first lens array 20, and in the present embodiment, the melted acrylic resin is injected. Then, when the molten resin is filled in the mold, a pressure holding step of holding the molten resin is performed (S30). The pressure holding step is performed to suppress the backflow of the molten resin in the mold cavity space, that is, to make the molten resin flow into the mold cavity space.

Next, a cooling step of cooling the molten resin is performed (S40). In the cooling step, the held resin is cooled until it solidifies. Although the temperature to solidify is suitably determined by the resin material etc. to be used, it is 90 degrees C or less as an example.

The method of manufacturing the first lens array 20 according to the present embodiment is characterized in the cooling step. In the cooling step, in addition to the heater being turned off, the mold, that is, the resin filled in the mold is cooled by circulating a coolant. That is, in addition to natural cooling due to the heater being turned off, forced cooling by circulating the coolant is performed. Thereby, the cooling time can be shortened. For example, the cooling time in the case of natural cooling alone is about 10 minutes, while the cooling time in the case of natural cooling and forced cooling is about 3 minutes.

In the cooling step, when the cooling time is long (for example, 10 minutes), a flat surface is formed on the light incident surface of the first lens array. Further, in the cooling step, when the cooling time is short (for example, 3 minutes), the light incident surface of the first lens array is greatly affected by the contraction of the resin at the time of cooling, whereby a recess is formed. For example, the shorter the cooling time, the higher the maximum depth of the recesses formed in the first lens array (depths L1 and L2 in FIG. 3). That is, in the cooling step, the shape of the light incident surface of the first lens array can be controlled by controlling the cooling rate of the mold.

In the prior art, it took time to cool in order to make the light incident surface flat. That is, it cooled by natural cooling.

On the other hand, in the present embodiment, the cooling time is set shorter than in the conventional case in order to form a recess in the light incident surface 21a. Specifically, in addition to natural cooling, forced cooling with a coolant is performed. That is, the speed of cooling the mold is controlled to be faster than in the past. Note that, by increasing the cooling speed in the cooling step, both the concave portions 22 and the individual concave portions 23 shown in FIG. 3 are formed. That is, both the recesses 22 and the individual recesses 23 can be formed by simple control such as adjusting the cooling rate of the mold in the cooling step.

The above-mentioned cooling time is the time required to cool the square first lens array 20 having a side of 110 mm. The cooling time may be appropriately determined by the size of the first lens array 20. Further, the cooling time may be shorter than 3 minutes, but in consideration of the influence on the light collecting characteristic of the first lens array 20, it may be about 3 minutes.

When the temperature becomes 90 ° C. or less in the cooling step and the resin solidifies, the step of taking out the first lens array 20 which is a resin molded article from the mold is performed (S50). In the first lens array 20 taken out in step S50, the recesses 22 and the individual recesses 23 shown in FIG. 3 are formed. That is, the recesses 22 and the individual recesses 23 are not formed by physical processing such as cutting, but are formed by the cooling conditions at the time of injection molding. Specifically, the concave portions 22 and the individual concave portions 23 are formed on the light incident surface 21 a of the first lens array 20 by shortening the cooling time in the cooling step (in other words, increasing the cooling speed).

[4. Effect etc]
As described above, the first lens array 20 according to the present embodiment includes the first lens array 20 in which the plurality of first lenses 21 (an example of the lenses) for condensing sunlight are disposed. It is an example of a lens array, and the first lens array 20 has a light incident surface 21a on which sunlight is incident, and a light emission surface 21b opposite to the light incident surface 21a and from which sunlight is emitted. And the recessed part 22 dented in the light-projection surface 21b side is formed in the light-incidence surface 21a over several 1st lenses 21. As shown in FIG.

As a result, the recess 22 is formed on the light incident surface 21 a of the first lens array 20, so that the wind 80 is disturbed by the recess 22 when the wind 80 blows on the light incident surface 21 a. Then, the dust 90 attached to the light incident surface 21 a can be removed by the disturbed wind 81.

Conventionally, the light exit surface of the first lens array is a flat surface, and the disturbed wind 81 has not occurred. That is, the dust removal ability by the wind 80 was low.

Therefore, with the first lens array 20 according to the present embodiment, the cleaning effect can be improved as compared to the related art. Moreover, since it can suppress that the dust 91 which floats on the light-incidence surface 21a adheres by the wind 81, the fall of the electric power generation efficiency by adhesion of the dust 91 can be suppressed.

Further, the depth of the concave portion 22 increases as it goes from the outer edge (peripheral edge) of the first lens array 20 to the center when the first lens array 20 is viewed from the light incident surface 21 a side.

Thereby, the removal capability of the dust 90 by the wind 80 is improved as it goes to the center of the first lens array 20.

Moreover, the external shape of the recessed part 22 is circular arc shape in the cross sectional view at the time of seeing from the direction orthogonal to the direction into which sunlight injects.

Thereby, the first lens array 20 having the arc-shaped concave portion 22 can be realized.

Further, the maximum depth L1 of the recess 22 is 20 μm or less.

This makes it possible to improve the cleaning effect of the light incident surface 21a more than the conventional one while suppressing the influence on the light collection characteristic of the first lens array 20.

Further, each of the plurality of first lenses 21 has a convex portion 24 (an example of an individual convex portion) that protrudes toward the direction in which sunlight is emitted on the light emission surface 21 b side of the first lens 21. The light incident surface 21 a is further formed with an individual recess 23 recessed toward the convex portion 24 corresponding to the first lens 21 for each of the plurality of first lenses 21.

As a result, the height of the recess is increased by providing the individual recesses 23 as compared with the case where only the recesses 22 are provided, so that the cleaning effect can be further improved.

Further, the maximum depth L2 of the individual recess 23 is 10 μm or less.

As a result, the effect of cleaning the light incident surface 21 a can be further improved while suppressing the influence on the light collection characteristic of the first lens array 20.

In addition, each of the plurality of first lenses 21 is a convex lens.

Thus, using a convex lens as the first lens 21, the first lens array 20 can be realized.

The first lens array 20 is formed of acrylic resin.

As a result, the cost and weight of the first lens array 20 can be reduced.

In addition, as described above, in the method of manufacturing the first lens array 20 according to the present embodiment, the method of manufacturing the first lens array 20 in which the first lenses 21 for condensing sunlight are arranged in an array. The method includes an injection step (S20) of filling a molten resin into a mold, and a cooling step (S40) of cooling the filled molten resin (melted resin). Then, in the cooling step, depressions (for example, recesses 22 and individual recesses 23) are formed in the light incident surface 21a on which the sunlight of the first lens array 20 is incident by controlling the speed at which the mold is cooled.

Thus, the recesses (for example, the recesses 22 and the individual recesses 23) can be formed by a simple method of controlling the cooling speed of the mold in the cooling step. For example, the recess can be formed more easily than in the case of forming the recess by cutting or the like.

Further, in the method of manufacturing the first lens array 20, the first lens array 20 in which the plurality of first lenses 21 are arranged in an array can be integrally manufactured by resin molding. The solar cell module 10 is easily manufactured by combining the first lens array 20 with the printed circuit board on which the power generation element 50 is mounted by surface mounting so as to correspond to the arrayed arrangement of one lens 21. be able to.

In the cooling step, the mold is cooled by the cooling liquid.

Thereby, the mold can be cooled by a simple method using a coolant. Further, the cooling time can be easily adjusted by adjusting the temperature or the like of the coolant.

(Other embodiments)
As mentioned above, although the lens array which concerns on an aspect, and the manufacturing method of the said lens array were demonstrated based on embodiment, this indication is not limited to this embodiment.

Therefore, among the components described in the attached drawings and the detailed description, not only components essential for solving the problem but also components not essential for solving the problem in order to exemplify the above-mentioned technology May also be included. Therefore, the fact that those non-essential components are described in the attached drawings and the detailed description should not immediately mean that those non-essential components are essential.

In addition, the embodiments can be realized by various combinations of the embodiments that can be conceived by those skilled in the art, or by combining components and functions of the embodiments within the scope of the present disclosure. Forms are also included in the present disclosure.

In the above embodiment, the first lens is described as an example of a convex lens, but the present invention is not limited to this. For example, the first lens may be a lens formed by injection molding. For example, the first lens may be a spherical lens, an aspheric lens, a Fresnel lens, or the like. For example, when the first lens is a Fresnel lens, the Fresnel surface may be on the light emitting surface side of the first lens. That is, it is preferable that asperities are formed on the light emitting surface of the first lens.

Although the solar cell module has been described in the above embodiment as an example including the first lens array and the second lens array, the present invention is not limited to this. The solar cell module may not have the second lens array.

Although the said embodiment demonstrated the example in which the recessed part and the separate recessed part were formed in the light-incidence surface, it is not limited to this. At least a recess may be formed on the light incident surface. That is, the individual concave portions may not be formed on the light incident surface.

Although the above-mentioned embodiment explained that a crevice and an individual crevice were dome shape depression, it is not limited to this. For example, the shapes of the recesses and the individual recesses may be triangular or other shapes in cross section. For example, the recesses and the individual recesses may be conical.

In the above embodiment, an example in which the depth of the recess when the size of one side of the first lens array is 110 mm is 20 μm or less has been described, but the depth of the recess corresponds to the size of the first lens array Can change. For example, the depth of the recess may increase as the size of the first lens array increases. That is, the maximum depth of the recess may be determined according to the size of the first lens array.

In the above embodiment, an example is described in which the depth of the individual recess is 10 μm or less when the size of one side of the first lens is 22 mm, but the depth of the individual recess is the size of the first lens It may change accordingly. For example, as the size of the first lens increases, the depth of the individual recesses may increase. That is, the maximum depth of the individual recesses may be determined according to the size of the first lens.

The lens array and the method of manufacturing the lens array according to the present disclosure can be applied to a lens array for collecting light. In particular, it is effective for the lens array for condensing used for a solar cell module.

10 solar cell module 20 first lens array (lens array)
21 First lens (lens)
21a light incident surface 21b light emitting surface 22 concave portion 23 individual concave portion 24 convex portion (individual convex portion)
Reference Signs List 30 second lens array 31 second lens 32 base portion 40 resin plate 50 power generation element 60 electrode 70 outer frame 71 support member 71 a support portion 71

b tip portion

80, 81

wind

90, 91 dust

Claims

A plurality of lenses are arranged in an array, and each of the plurality of lenses is a lens array for collecting sunlight,
A light incident surface on which the sunlight is incident;
A light emitting surface located opposite to the light incident surface and from which the sunlight incident on the light incident surface is emitted;
The light incident surface is formed with a concave portion recessed on the light emitting surface side across the plurality of lenses.
Lens array.
The concave portion increases in depth as it goes from the periphery to the center of the lens array when the lens array is viewed from the light incident surface side.
The lens array according to claim 1.
The concave portion has an arc shape in a cross sectional view when viewed from a direction orthogonal to the direction in which the sunlight is incident.
The lens array according to claim 1.
The maximum depth of the recess is 20 μm or less.
The lens array according to any one of claims 1 to 3.
Each of the plurality of lenses is
It has an individual convex portion that protrudes toward the direction in which the sunlight is emitted on the light emitting surface side,
It has an individual recess recessed toward the individual convex portion on the light incident surface,
The lens array according to any one of claims 1 to 4.
The maximum depth of the individual recess is 10 μm or less.
The lens array according to claim 5.
Each of the plurality of lenses is a convex lens,
A lens array according to claim 5 or 6.
The lens array is formed of acrylic resin,
The lens array according to any one of claims 1 to 7.
A manufacturing method of a lens array in which a plurality of lenses are arranged in an array and each of the plurality of lenses condenses sunlight,
An injection process of filling the molten resin into a mold;
Cooling the filled resin;
In the cooling step, a concave portion is formed over the plurality of lenses on a light incident surface of the lens array on which the sunlight is incident by controlling a cooling rate of the mold.
Method of manufacturing lens array.
In the cooling step, the mold is cooled by a cooling liquid.
The manufacturing method of the lens array of Claim 9.