JP2008098533A - Method for collecting light, and light collecting plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide: a method for collecting light capable of collecting the sunlight regardless of direction or altitude; a light collecting plate; and a solar collection tower applying the same. <P>SOLUTION: Incident beam from a wide angle is gradually focused into a light beam perpendicular to a plane of incidence with a rectifier unit to condense the incident beam, and a leaked light beam is sequentially focused with the rectifier unit at a next stage. In collecting the sunlight, a collected light beam in a horizontal direction is irradiated to the ground with the optical angle changing plate. The sunlight and a scattered light from all altitude and all direction can be collected by arranging the light collecting plate and the optical angle changing plate on the outer wall surface of the solar collection tower without requiring a sunlight tracking device. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a condensing method for condensing light beams from a wide-angle range, such as sunlight, into a narrower range of light in a stepwise manner, and a condensing plate based on this condensing method.

  In a device that uses solar cells to generate power from sunlight, in consideration of the altitude and direction of the sun, which fluctuates depending on the season and time, it is tilted southward so that the power generation efficiency of a flat solar cell is the highest. However, since the amount of power generation is proportional to the projected area of the solar cell in the direction of the sun, solar cells can be installed on a large site area so that the batteries do not overlap in order to secure the amount of power generation. It was necessary to install so as to spread. In order to save the installation area, a method of stacking solar cells in multiple stages at appropriate intervals can be considered, but the upper battery is blocked by sunlight and the power generation efficiency of the lower battery is extremely reduced. However, there was a disadvantage that it was expensive and lacked practicality.

  In addition to the above-described method of directly irradiating solar cells with sunlight, condensing the solar cells by condensing sunlight using some kind of optical device, such as combining a reflector, prism, or lens. There is a solar power generation method. However, in any of the methods, it has been necessary to always track the sun with a solar tracking device in order to increase efficiency.

For this reason, light collecting plates that can collect light regardless of the direction and altitude of the sun are stacked in a tower shape at a predetermined interval to condense solar rays, and the solar cells on the bottom surface of the tower are irradiated to generate power. A concentrating tower of methods has been proposed.
Japanese Patent Application No. 2006-219105

  However, in the proposed method, the direct light incident from the top of the tower is transmitted through the lower light collector and reaches the solar cell. However, there is a risk that a considerable loss occurs and the practical efficiency is lowered as a result of repeated light processing loss, surface reflection loss of the constituent members, light transmission loss of the material itself, and the like. The development of a highly efficient light collection method that can collect light from all directions without requiring a solar tracking device is an issue.

  In order to collect solar rays from all directions at all altitudes and supply them to the solar cells, a light collector plate is arranged almost vertically on the outer peripheral surface of the light collecting tower, so that sunlight from morning and evening horizontal directions can also be observed from mid-day sky. The above-mentioned problem is solved by a condensing method and a condensing plate that can convert all of the sunlight into light beams in the vertical direction and irradiate the solar cell.

  The condensing method used for the condensing plate of the present invention is a condensing method for condensing step by step by laminating concentrating plates formed by connecting innumerable rectifying units that narrow and converge light beams from a wide direction little by little. In this proposal, a light collecting plate formed by connecting rectifying units, a light angle conversion plate for changing the direction of light collected by the light collecting plate in an arbitrary direction, and a solar light collecting tower using the light collecting plate are proposed. is there.

  The condensing method of the present invention is a rectifying unit made of an obtuse angled triangle with the bottom inclined downward, and a transparent condensing plate having a sawtooth cross section on the front and back, and one surface of the rectifying unit is the surface of the condensing plate The bottom surface of the obtuse triangle is inclined with respect to the light collecting plate surface at an angle smaller than the maximum refraction angle to make the light incident surface, and the remaining one surface has a maximum refraction angle of 2 with respect to the incident surface. Inclined in the same direction as the incident surface at an angle of 1 or less per minute to make the light exit surface, and the angle of inclination of the entrance surface and the exit surface was set so as to narrow the angle range of the exit light with respect to the angle range of the incident light This is a condensing method characterized in that the angle of light incident on the rectifying unit is narrowed stepwise and rectified.

  The condensing plate is formed by connecting an infinite number of rectifying units. From the outside, both the front and back surfaces are saw-toothed plates, and the range of incident light that can be rectified is 0 to 90 degrees. In order to collect light rays from all directions from plus 90 degrees to minus 90 degrees, it is only necessary to stack two light collecting plates with opposite inclinations.

  A light beam condensed and emitted from the light collecting plate becomes a light beam perpendicular to the surface of the light collecting plate, but the direction can be changed to an arbitrary direction using the light angle conversion plate. The conversion unit is a parallelogram surrounded by an incident surface of incident light, an exit surface parallel to the incident surface, and upper and lower conversion surfaces, and the inclination angle of the conversion surface is approximately one half of the angle to be converted. The angle-of-light conversion plate is a stack of innumerable conversion units.

  Moreover, the solar condensing tower is constructed by combining the laminated condensing plate and the light angle conversion plate so that the light emitted from the condensing plate is irradiated toward the lower surface of the solar condensing tower.

  The light collector is a transparent plate that is formed of a homogeneous transparent material and has a saw-tooth shape on both sides. In the case of using a normal material, by laminating 2 to 4 sheets, it is possible to narrow light rays from all directions of 0 to 90 degrees to an angle range of approximately one half or less. Further, in order to narrow down the light condensing range, the light can be condensed in a narrower range by stacking light collecting plates having different inclination angles.

  As described above, the condensing method and the condensing plate of the present invention can condense light beams from all directions by narrowing the range in the direction perpendicular to the condensing plate surface. For this reason, it is possible to condense a light beam of a spherical light source such as a headlight, a projector, or a ceiling illumination in a range to be illuminated, or to block a light beam leaking outside the illumination range to suppress glare and energy loss. In addition, the light collecting tower does not require a device for tracking the sun unlike conventional light collecting methods, and can collect sunlight at all altitudes at all altitudes on the tower bottom surface. A large area of sunlight can be collected and irradiated. Furthermore, not only the direct light but also the scattered light from all directions can be collected even in cloudy weather, and the cost can be reduced as a whole. The condensing tower can be applied to a hot water supply device using solar heat or a light duct for indoor lighting using natural light.

  Hereinafter, the light collecting method that is the basis of the present invention will be described with reference to FIG. For ease of understanding, the altitude from the horizontal direction (morning sun or sunset) to the direct upward direction during the day is 0 to 0 when the light collecting plate is used vertically on the outer wall surface of the light collecting tower. The case where 90 degree sunlight rays are condensed is demonstrated. When the light collecting plate is installed horizontally on the light collecting tower or the ceiling of the building, it is natural that the light rays from above can be condensed downward. Therefore, the angle of the light ray incident on the light collector is in the range of 0 to 90 degrees. However, the light condensed by the light collector may be further narrowed and condensed, or sunlight with an altitude of 90 degrees may be equator. Since there is no real thing unless it is directly below, and the morning sun and sunset near the horizontal are weak, there are some aspects that are more convenient for the design of the light collecting plate, so the range of light rays incident on the light collecting plate is not necessarily It is not in the range of 0 to 90 degrees. A condensing plate suitable for the range of the incident light with the maximum angle to the incident light with the minimum angle can be designed in the shape of the rectifying unit.

  As shown in FIG. 1, the light collector 1 is formed by connecting a rectifying unit 2 having an obtuse triangle with an infinite number of vertical sections by inclining the base of the obtuse triangle serving as the light incident surface 3 downward at an angle α. . One side of the obtuse angled triangle is substantially perpendicular to the light collecting plate surface 7 as the upper surface 5 of the rectifying unit, and the other side is inclined as the light exit surface 4 in the same downward direction as the incident surface at an angle β. Further, the upper and lower rectifying units 2 are connected to each other at a connecting margin 6 from a vertex a where the incident surface 3 and the exit surface 4 intersect to a right end b on the upper surface.

  Sunlight at an altitude of 90 degrees is a light ray incident at the maximum angle with respect to the light collector plate surface 7 and refracts at the incident surface according to the refractive index of the material and travels through the rectifying unit, and then refracts again at the exit surface. It is injected. Sun rays from the horizontal direction at an altitude of 0 degrees are incident light at a minimum angle, and are similarly refracted and emitted from the exit surface according to the angle difference from the incident surface. By appropriately selecting the inclination angle between the incident surface and the exit surface, the angle range of the emitted light can be reduced from the angle range of the incident light.

  When a light ray enters the transparent material, it is refracted according to the incident angle. However, when the refractive index of the material is k and the light incident angle is θ, the refraction angle is asin (sin θ ÷ k). Of the light beam angles to be collected, the refraction angle of the light beam having an angle corresponding to the difference between the maximum incident angle and the minimum incident angle to be collected is referred to as a maximum refraction angle. Sunlight has an incident angle in the range of 0 to 90 degrees, but the 90-degree light beam does not exist in Japan, or the light near the 0-degree horizon line is weak and less practical, so you can exclude it. There is a case where it is desired to further reduce the range after focusing down and focus the light. For example, when condensing light of 0 to 45 degrees, the maximum refraction angle at k = 1.5 and θ = 45 is about 28. Degree. In addition, the direction of the light ray in the ray path diagram 2 is drawn according to the actual situation.

  In order to collect light with the light collector, the absolute condition is that the rectifying unit is an obtuse triangle and the base is inclined with respect to the incident surface. If the rectifying unit is a right triangle, the condensing plate has the same shape as the backlight prism sheet of the liquid crystal display panel. In this case, however, the direction of the emitted light is further expanded as shown in FIG. When the layers are stacked, the light is inverted by repeated total reflection, and a light beam emitted to the incident surface side is generated and cannot be condensed.

  In addition, if the inclination angle of the incident surface is made extremely small, the refraction at the rectifying unit becomes gentle as shown in FIG. 4, and the generation of light rays that are totally reflected and scattered by the upper surface can be suppressed, or the upper surface compared to the incident surface. However, it is difficult to collect light within a specified range without stacking multiple light collectors, and the surface reflected light is emitted directly to the incident side, resulting in a loss. There is an inconvenience that the number of stacked layers increases and the surface reflection loss increases, resulting in a drastic decrease in light collection efficiency as a whole.

  On the other hand, when the inclination angle of the exit surface is extremely large, among the light rays traveling in the rectification unit as shown in FIG. 5, the light rays that hit the upper surface of the rectification unit and diffuse back from the light collection direction due to total reflection increase. Therefore, it is necessary to go through a large number of rectifying units before being ejected, so that the loss such as surface reflection tends to increase.

  In order to increase the light collection efficiency, basically all incident light is collected and emitted from the exit surface, light loss due to surface reflection is reduced, and surface reflected light when entering and exiting the light collecting plate. It is important that the total reflected light can be directed as an effective ray. For this purpose, the inclination angle of the incident surface is inclined from the angle close to the maximum refraction angle with respect to the light collecting plate surface to an angle smaller than that, and the inclination angle of the exit surface is half of the maximum refraction angle with respect to the incident surface. It is desirable to incline at the following angles, which is also the main point of this condensing method.

  Fig. 2 shows a condensing plate using general glass or acrylic resin with a critical angle of about 42 degrees (refractive index 1, 5). The incident surface has an inclination angle of 38 degrees and the exit surface has an inclination angle of 69 degrees. The light beam path of the light collecting plate is shown. Sunlight from directly above an altitude of 90 degrees (maximum angle) is a non-practical ray that hits only the tip of the rectification unit. A light beam with an altitude of 75 degrees is shown as a light beam path p75u, and a light beam with an altitude of 15 degrees is shown as a light beam path p15n, but the light is emitted from the exit surface of the final stage light collecting plate after repeating refraction and total reflection. The p number attached to the light path indicates the height of the incident light. Further, the suffix u is a light beam incident from the left end of the upper surface of the rectifying unit, n is a light beam incident from the right end of the upper surface, s is a light beam incident on the lower end of the incident surface, and m is incident from the middle of the incident surface. Represents all rays, and all rays will be incident on these points.

  In the optimum specification, the incident light from each direction is rectified at the minimum number of times and is emitted from the exit surface of the final light collector. However, if there is only one light collector, the direct exit surface from the coupling allowance A light beam leaking to the side may be generated, or a light beam emitted in the direction of diffusion may be generated. These disadvantages can be almost eliminated by stacking several light collecting plates. In addition, when the material is general transparent glass or transparent resin, surface reflection of about 4% occurs on one side, but it can be condensed as an effective light beam by properly tilting the entrance and exit surfaces. And surface reflection loss can be minimized.

  The light collecting plate can collect light in a range of 90 degrees from light in a direction perpendicular to the light collecting plate to light in a direction parallel to the plate in a direction perpendicular to the plate. To condense light rays in the opposite direction (minus 90 to 0 degrees) parallel to the surface of the light collecting plate, two light collecting plates with opposite inclination angles are overlapped to form an angle from directly below (right to left) The 180 degree light beam can be condensed as a light beam perpendicular to the plate surface.

  When the light collecting plate is formed of a material having a higher refractive index, it is possible to easily reduce the size and manufacture the light collecting performance. In addition, in order to stack the light collecting plates to form a laminated light collecting plate, the points of the stacked light collecting plates may be joined by spot welding. In addition, since the connection allowance is not directly related to the control of the light beam, its thickness should be set so as not to affect the traveling light beam in consideration of manufacturing convenience and the required strength of the product, but the thinner one should be as much as possible. Since the size can be reduced, 0.01 to 2 mm is appropriate. Note that the transparent material for forming the light collector may be colorless or colored as long as it is a material that transmits light. If a soft resin is used, it can be formed as a flexible sheet. Further, since the function of the condensing plate is similar and does not change even if it is reduced, it can be expected that the light condensing plate is reduced in size and made extremely thin. The light-condensing plate made of transparent resin can be manufactured by a general molding method such as injection molding or press molding.

  FIG. 6 shows a light angle conversion plate 11 in which light rays collected in a direction (horizontal direction) perpendicular to the surface of the light collecting plate are converted in a vertical direction parallel to the plate surface or in an arbitrary direction in the light collecting plate arranged vertically. 9 is a parallelogram conversion unit surrounded by a vertical incident surface 3, an exit surface 4 parallel to the incident surface, and upper and lower conversion surfaces 10 which are inclined. The inclination angle γ of the conversion surface is set to approximately one half of the angle whose direction is to be converted. The length w of the conversion unit is set to the length w up to the conversion point at which all of the light rays perpendicularly incident on the incident surface are totally reflected by the conversion surface. The light angle conversion plate 11 is formed by stacking innumerable conversion units 9 in the vertical direction, and the upper and lower conversion units are connected to each other at a connection allowance 6 on the entrance surface and the exit surface. There is a minute gap between each conversion unit, and causes total reflection at the interface with the gap. The width of the gap is not particularly limited as long as the function of total reflection functions, but it is usually set in the range of about 0.01 to 2 mm from the viewpoint of ease of manufacturing, quality, and the like.

  When the horizontal light beam collected by the light collector is incident on the conversion unit 9, regardless of the position between the point a and the point b on the incident surface 3, the light strikes the conversion surface 10 and undergoes a total reflection only once. After conversion, the light is irradiated from the radiation surface 4. When a material having a critical angle of about 42 degrees is used and the tilt angle γ is set to 21 degrees, the direction of the converted light beam is doubled to 42 degrees, and the direction of the light beam emitted from the light angle conversion plate 11 is It can be converted by 90 degrees. By changing the inclination angle in the range of 0 to 21 degrees, the angle can be converted into an arbitrary direction.

  A condensing plate and a light angle conversion plate may be combined in order to collect sunlight rays on the bottom surface of the concentrating tower. FIG. 7 shows a condensing tower 12 in which a condensing plate 1 is attached to the outer wall surface, a light angle conversion plate 11 is attached to the inner surface, and the condensing plate 1 is attached to the ceiling. The light is condensed and irradiated downward. The light collected by the light collecting plate on the ceiling is shown as it is condensed and irradiated directly under the tower without changing its direction. The planar shape of the tower may be square or circular. In the case of a circular shape, the light collecting plate and the light angle conversion plate may be curved in accordance with the circumference of the tower. In addition, a rectangular light collecting plate may be cut and installed on the ceiling light collecting plate, but a circular light collecting plate that is radially rounded from the outer periphery toward the center may be arranged. In this case, the range of light rays that can be collected from the center to the left and right is reversed, so by overlapping two circular light collectors with opposite inclination angles, sunlight from all left and right angles can be centered inside the tower. Can be condensed and irradiated. Circular concentrator towers have the advantage of being able to uniformly collect sunlight that fluctuates depending on the season and time. The solar cell 12 is installed on the floor of the tower where the collected light hits.

  When the light collector is applied to an antiglare louver for ceiling lighting or the like, light from a light source irradiated in a wide direction can be narrowed down to a light beam of 50 degrees or less. In this case, it is possible to prevent glare from multidirectional angles by superimposing light collecting plates with opposite gradients.

It is sectional drawing of the light-condensing plate by this condensing method. It is a light beam path | route figure in the laminated light-condensing plate. It is explanatory drawing of the light ray path in the condensing plate from which an angle differs. It is explanatory drawing of the light ray path in the condensing plate from which an angle differs. It is explanatory drawing of the light ray path in the condensing plate from which an angle differs. It is sectional drawing of a light angle conversion board. It is a cross-sectional model figure of a condensing tower.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, Light-condensing plate 2, Rectification unit 3, Incidence surface 4, Emission surface 5, Upper surface 6, Connection cost 7, Light-condensing plate surface 8, Laminated light-condensing plate 9, Conversion unit 10, Conversion surface 11, Light angle conversion plate 12, Sun Condensing tower 13, solar cell

Claims (5)

  In a rectifying unit composed of an obtuse angled triangle with the bottom inclined downward, a transparent condensing plate with a sawtooth cross-section on the front and back, and one surface of the rectifying unit is an upper surface substantially perpendicular to the condensing plate surface, The bottom surface of the obtuse triangle is inclined at an angle less than the maximum refraction angle with respect to the light converging plate surface to make the light incident surface, and the remaining one surface is an incident surface with an angle less than one half of the maximum refraction angle with respect to the incident surface. The light condensing method is characterized in that the angle of inclination of the incident surface and the exit surface is set so as to narrow the angle range of the exit light beam relative to the angle range of the incident light beam.   2. The light collector according to claim 1, wherein the upper and lower rectifying units are connected with a connection margin of 0.01 to 2 mm in thickness.   A condensing method comprising: laminating a plurality of condensing plates according to claim 2, and condensing by concentrating the angle range of incident light in stages.   In the parallelogram conversion unit surrounded by the incident surface of the light beam, the exit surface parallel to the incident surface, and the upper and lower conversion surfaces that are inclined, the inclination angle of the conversion surface is approximately one half of the angle to be converted. The angle is the length up to the point at which all incident light incident perpendicularly to the incident surface is totally reflected by the conversion surface, and this conversion unit is stacked to convert the traveling direction of the light. A light angle conversion plate characterized by that.   A solar concentrator tower, wherein the light collector plate according to claim 2 and the light angle conversion plate according to claim 4 are arranged vertically on the outer periphery of the light collector tower so that the light collector plate is located outside.

Images