JP2010102206A - Solar lens - Google Patents

Abstract

[PROBLEMS] To propose a solar lens that applies total reflection of light as a method of concentrating solar rays regardless of the azimuth or altitude of the sun. A conical auxiliary lens is provided on the bottom of an inverted frustoconical main lens. In the case of a solar lens embedded in the same axis, there is a disadvantage that a part of the light rays cannot be condensed and lost regardless of the altitude of the sunlight. To provide a solar lens that can reduce lost light rays.
By forming a slope 7 of an auxiliary lens 3 in a sawtooth shape like a bevel gear, a light beam traveling toward the auxiliary slope 7 is totally reflected and condensed on the main lens 2 side of the light exit surface. By configuring, the loss of light is suppressed. Further, by using the bevel gear-shaped auxiliary lens 3, the surface reflection loss when the solar lenses 1 are stacked in multiple stages is suppressed, and the above-described problem is solved.
[Selection] Figure 1

Description

  The present invention relates to an improvement of a solar lens aimed at condensing a sunlight ray whose altitude and azimuth are constantly moving in a certain range narrower than a light receiving area with a stationary lens.

As a method for concentrating sunlight rays regardless of the direction and altitude of the sun, a condensing method using total reflection of light has been proposed.
Japanese Patent Application No. 2007-248288 Solar Lens

  The method of Patent Document 1 is a solar lens in which a conical auxiliary lens is coaxially embedded in the bottom surface of an inverted frustoconical main lens, and the outer slope of the main lens and the slope of the auxiliary lens face each other in a V shape. Since it has a simple shape, there is a drawback in that the light collection performance is low due to the large proportion of light rays that have undergone total reflection between them transmitted through the outer slope of the main lens. In addition, when the light collecting magnification is increased, if it is laminated in multiple stages, there is a drawback that the performance is remarkably lowered due to the addition of surface reflection loss on the laminated surface. An object of the present invention is to reduce this light loss.

  By forming the inclined surface of the auxiliary lens in a sawtooth shape like a bevel gear, the light traveling from the main lens toward the auxiliary lens is repeatedly totally reflected by the auxiliary inclined surface of the sawtooth, and is divided into a sawtooth shape. The above-described problem is solved by concentrating mainly on the light exit surface on the main lens side at the boundary between the lens and the auxiliary lens.

  The conical auxiliary lens repeats total reflection with the outer slope of the main lens, whereas it repeats total reflection between the auxiliary slopes of the sawtooth auxiliary lens. Light that can be condensed on the main lens side and transmitted through the outer slope of the main lens to be lost can be blocked. In addition, when the solar lens is laminated, the main lens side of the light exit surface and the main lens of the next stage can be formed integrally, so that the interstage is larger than the method of laminating the solar lens composed of conical auxiliary lenses. Since there is no surface reflection loss, there is an advantage that deterioration of the light collecting performance can be suppressed even when stacked in multiple stages.

  FIG. 1 shows a longitudinal section of a solar lens 1 according to the present invention. A sun-shaped solar lens 1 having a W-shaped section formed by concentrically embedding a conical auxiliary lens 3 into the bottom surface of an inverted frustoconical main lens 2. In the lens, the auxiliary inclined surface 7 of the auxiliary lens forms a saw-toothed inclined surface like a bevel gear, and the main lens and the auxiliary lens are optically separated by a minute gap 9 (not shown). .

  In the solar lens, the incident sunlight 4 with the upper surface of the main lens as the light incident surface 4 is totally reflected on the outer inclined surface 6 of the main lens and the auxiliary inclined surface 7 of the auxiliary lens so as to be condensed on the light emitting surface 5 on the lower surface of the solar lens. The inclination angle α1 between the outer slope 6 of the main lens and the auxiliary slope 7 of the auxiliary lens is appropriately set so that the traveling light beam does not diffuse through the outer slope after repeated total reflection. The whole is made of transparent material. In the following explanation, the inclination angle of the outer and auxiliary slopes of the main lens and auxiliary lens, and the inclination angle of the light beam are indicated by the inclination angle with respect to the vertical plane when the solar lens is installed horizontally unless otherwise specified. To do.

  A light ray incident from the light incident surface is either directly or totally reflected at the outer slope of the main lens and travels toward the auxiliary slope of the auxiliary lens. FIGS. 3 and 4 illustrate the path of the light beam. In addition, the paths of the light rays p1 and p2 entering from the points m1 and m2 are displayed separately for the downward component in FIG. 3 and the circumferential component in FIG.

  The maximum tilt angle of the sun rays with respect to the light entrance surface is 90 degrees (sunrise / sunset), so when the light entrance surface is horizontal, the tilt angle of the light rays entering the main lens from the light entrance surface is the critical refraction angle of the constituent material. It will proceed at the following angles. For example, in a solar lens using an acrylic resin having a critical refraction angle of 42 degrees (refractive index of about 1.5), the main lens outer slope has an inclination angle α1 of 6 degrees and a light incident surface has an inclination angle α2 of 90 degrees. When the light ray from the horizontal direction (Chaoyang) that refracts to the maximum as the incident ray travels in the radial direction from the point m2 and hits the outer slope, the incident ray goes out at an inclination angle of 42 degrees as shown in the ray trajectory of FIGS. After being totally reflected on the slope, it reverses and proceeds to the auxiliary slope at an inclination angle of 54 degrees.

  The light beam travels in various directions depending on the position where it hits the auxiliary slope, but since the auxiliary slope is finely divided in a sawtooth shape around the entire circumference, the inclination angle of the slope is small, so most of the light rays after repeated total reflection Reaches the main lens side of the light exit surface.

  In addition, some light rays that pass through the auxiliary slope and enter the auxiliary lens are divided into light rays that repeat total reflection on the auxiliary slope from the inside of the auxiliary lens and light rays that pass through the auxiliary slope again and reach the outer slope. However, since the auxiliary lens has a conical shape as a whole, the inclination angle of the light beam that repeats total internal reflection gradually decreases and reaches the auxiliary lens side of the light exit surface to be condensed.

  The auxiliary slope is also totally reflected in the circumferential direction, so many of the rays that pass through the auxiliary lens again and reach the outer slope are mostly totally reflected again on the outer slope and head toward the auxiliary slope. Also passes through and becomes a lost light beam.

  In the case of a bevel gear-shaped auxiliary lens, the auxiliary lens is simply a conical sun lens, whereas a part of the light beam is a lost light beam regardless of the tilt angle of the incident light beam (regardless of the altitude of the sun). Loss may occur only for light rays with a large inclination angle that enter from a substantially horizontal direction, such as morning and evening. In order to suppress these lost rays, it is possible to adjust most by appropriately selecting the inclination angle of the outer slope of the main lens and the inclination angle of the auxiliary lens. An acute angle is considered effective.

  The condensing magnification of the present sun lens can be expressed by the area ratio of the light incident surface and the light exit surface, but in order to increase the light condensing magnification, the solar lenses may be stacked in a plurality of stages. FIG. 5 shows a case where three layers are stacked. In this case, the condensing magnification is 3 (number of stacked layers) times the condensing magnification of the single unit.

  FIG. 6 is a cross-sectional view of another application example. The conical cylinder 10 (portion above the partition line of h2) having the same inclination angle as that of the main lens is connected to the light incident surface of the sun lens in FIG. 1 so as to be continuous with the main lens and the auxiliary lens. Incident sunlight rays are collected in the same manner as in FIG. 1 through paths indicated by p3 and p4 in the figure. The condensing magnification is an area ratio between a wider light incident surface and a light exit surface formed by extending, but the space portion 9 of the conical cylinder does not function effectively and needs to be excluded.

  Note that the function of the solar lens does not change even if the solar lens in FIG. 1 is cut horizontally along the partition line h and the upper portion thereof is removed. In this case, since the tip portion of the auxiliary lens becomes a cavity, the condensing magnification is the ratio of the area of the light exit surface to the area obtained by subtracting the area of the cavity from the area of the cut surface.

  In the above description, the light rays p1 and p2 that are incident at the maximum inclination angle in the radial direction from the center of the lens that is most likely to leak from the outer slope have been described as an example. When the incident light beam is totally reflected by the outer slope, the tilt angle becomes smaller than that of the light beam traveling from the center in the radial direction, so that the light can be reliably collected without being lost through the outer slope.

  FIG. 7 shows a hemispherical surface of the light incident surface, a plurality of main lenses described in FIG. 6 are stacked concentrically through a minute gap, and the slope of the conical cylinder has a radius of curvature corresponding to the refractive index of the material. It shows another application example curved by. The incident light beam travels through a path such as the light beams p6 and p7 by total reflection, and after reaching the auxiliary lens, it is collected through a path substantially similar to the light beams p1 and p2 in FIGS.

  By making the main lens into a hemispherical shape as shown in FIG. 7, the projection area is enlarged, so that it is easy to collect sunlight with a low altitude. Moreover, the length of the sun lens can be relatively shortened by making the main lens have a shape that expands like a morning glory. By dividing the main lens into multiple layers, the thickness of the main lens can be relatively reduced, so that the radius of curvature of the main lens slope can be made smaller, and the sun lens can be made smaller overall. become. However, in order to stack curved conical cylinders, it is necessary to gradually reduce the thickness of the conical cylinders toward the center, and therefore there is a limit to the inclination of the outer slope in order to collect light without loss.

  Since the gap between the main lens and the auxiliary lens (not shown) and the gap between the main lenses stacked concentrically are for optically separating each other, total reflection occurs at the boundary between the gaps. If it is in a state, it may be a minute gap of 1 micron or less. In order to maintain the air gap, methods such as providing minute protrusions at appropriate intervals on the surfaces of the main lens and the auxiliary lens, or spraying fine powder at rough intervals can be considered.

  As described above, in the solar lens of the present invention, the auxiliary lens is formed with a sawtooth-like slope like a bevel gear, so that most incident light rays are collected without loss as compared with a solar lens constituted simply by a conical auxiliary lens. There is an advantage of being able to shine. Moreover, even if it is laminated in multiple stages in order to increase the light collection magnification, it is possible to condense through the main lenses that are continuous with each other.

It is a longitudinal cross-sectional view of a solar lens. It is a bottom view of a solar lens. It is sectional explanatory drawing for demonstrating the beam path of an axial direction. It is plane explanatory drawing for demonstrating the beam path of a radial direction. It is sectional explanatory drawing of the solar lens laminated | stacked in multiple steps. It is sectional explanatory drawing of another Example. It is sectional explanatory drawing of a different Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, Sun lens 2, Main lens 3, Auxiliary lens 4, Light entrance surface 5, Light exit surface 6, Outer slope 7, Auxiliary slope 8, Gap 9, Space portion 10, Conical cylinder

Claims (1)

  In a sun lens with a W-shaped cross section formed by concentrically embedding the conical auxiliary lens into the bottom of the inverted frustoconical main lens, the auxiliary inclined surface of the auxiliary lens is formed in a sawtooth shape like a bevel gear. A solar lens characterized in that a light beam incident from the light incident surface of the main lens is condensed on the light output surface by total reflection.

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