JPS59206801A - Condensing device - Google Patents

Abstract

PURPOSE:To increase a condensing ratio with a simple construction by providing plural pieces of transparent prisms which conduct the incident light having an incident angle in a specific range to a photodetecting surface by utilizing total reflection or specular reflection into multiple stages spaced from each other. CONSTITUTION:Incident light F which is made incident at an incident angle h1 to a transparent prism 11 is refracted by the surface 11a of the prism 11, advances rectilinear in the prism 11 and is totally reflected by the rear surface 11b of the prism 11. Such total reflection is repeated by the surface 11a and the rear surface 11b of the prism 11 until the incident light arrives at a photodetecting surface 11c provided at the terminal part of the prism 11. The max. permissible angle h1max of the light F is analytically determined with the incident light within the meridian perpendicular to the surface 11c and the surface 11a of the prism 11.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light condensing device using a prism.

FIG. 1(a) shows a light condensing device using a prism.

There are a transparent prism shown in (b) and a mirrored prism shown in FIG.

Figures 1(a) and 1(b) show an ordinary wedge-shaped prism used as a light condensing device by utilizing total internal reflection. 1st
In the figure, 11 is a transparent prism, and 11C is a light receiving surface. Incident light F that entered the transparent prism 11 at an incident angle of
is refracted at the surface 11a of the transparent prism 110,
The light travels straight through the transparent prism 11 and is totally reflected on the back surface 11b of the transparent prism 11. This total reflection is repeated on the front surface 11a and back surface 11b of the transparent prism 11, and the incident light F is reflected on the light receiving surface 11 provided at the end of the transparent prism 11.
reach c.

The maximum permissible angle h of the incident light F in the condensing device with the above structure
1mal is the light receiving surface 11c and the surface 1 of the transparent prism 11.
The incident light in a plane (meridional plane) perpendicular to 1a can be analytically determined. Incident light not included in the meridian plane (
Since the maximum permissible angle for oblique incident light requires complex calculations using ray tracing methods, etc., we will only consider the permissible angle for incident light in the meridian plane below.

Maximum allowable angle of incidence h in the meridian plane of the transparent prism shown in Figure 1
lIn□ is hlnn, x=:cosl(n (cos-'(-)10α)) ......(The maximum condensing ratio 'FL
m1 is cos h Rmax = sin m, x-・・・・・・・・・・・・
・・・・・・・・・・・・(2) However, n is the refractive index of the prism, and α is the apex angle of the transparent prism.

In addition, in the condensing device shown in FIG. 1, the transparent prism 11
Similarly, the light F' incident from the back surface 11b of the light receiving surface 11c
Light can be focused on. In this case, the maximum allowable angle of incidence HIffla
X is HIIBHK = 2 h Hma X-α...
・・・・・・・・・・・・・・・ (3)

Next, the mirrored prism condenser shown in FIG. 2 is one in which a back surface 21bKj mirror 22 of a transparent prism 21 is installed. The light F incident on the surface 21a of the transparent prism 210 at an incident angle h1 undergoes specular reflection on the mirror 22 on the back surface and reflection on the surface 21a on the surface 210.
It repeats total reflection at 1a and reaches the light receiving surface 21cK. Since the back surface 21b is a mirror surface, the incident light from the back surface 21b cannot be focused, but the maximum allowable incident angle h1mmK for the incident light from the front surface 21a is larger than when there is no mirror 22, and is given by the following equation. .

The upper limit of the condensing ratio is determined by the permissible angle of the condenser, and it is not possible to obtain a very large condensing ratio.

This invention was made in order to solve such problems, and a plurality of condensers using the above two types of prisms are arranged with a gap between them, and the condensing effect is adjusted according to the angle of incidence. It is characterized by the transparent prism that changes automatically. As a result, the instantaneous light collection ratio is not limited by the permissible angle, and a high light collection ratio can be achieved.

Chapter 1 Table FIG. 3 is a diagram showing an embodiment of the present invention.

In the same figure, two transparent prisms 31 and 32 are overlapped, and KiJIM is formed between the transparent prism 31 and the transparent prism 32.
β is provided. Light F1 incident at an incident angle o-h
is repeatedly totally reflected within the transparent prism 31, and the light-receiving surface 31
reach c. Similarly, the incident light F2 that is incident at an angle of incidence of one person, ~h, is focused on the light receiving surface 32c. Also, like the original light incident from the back surface 32b of the transparent prism 32, the light is focused on either of the transparent prisms 31 and 32 depending on the angle of incidence.

When a plurality of transparent prisms are stacked in multiple stages as described above, the incident light F is repeatedly totally reflected and focused within any one of the plurality of transparent prisms depending on its angle of incidence. A concentrator in which the light-receiving surface is automatically switched in accordance with the incident angle is particularly effective when sunlight is used as thermal energy. That is, since light is concentrated in one of the transparent prisms depending on the position of the sun, high-temperature heat can be collected with high efficiency. In this case, it goes without saying that the number of transparent prisms to be superimposed can be selected as appropriate.

FIG. 4 is a diagram showing another embodiment of the present invention, in which the lowermost transparent prism 32 in the embodiment shown in FIG. 3 is replaced with a mirrored prism 42, and 41 is a transparent prism. Since the mirror 43 is located at the bottom stage, the incident light from this surface cannot be used, but the maximum permissible angle for the incident light from the top surface is larger than that of the embodiment shown in FIG. That is, the angle of incidence oh.

The incident light at an angle of incidence h1 to h is focused on the light receiving surface 41c, and the incident light at an incident angle h1 to h is focused on the light receiving surface 42c.

Further, when the light is focused on a part other than the mirror-equipped prism 42 at the lowest stage, the reflection on the ζ mirror surface 43c is less than one time, and the loss due to specular reflection is considerably reduced.

FIG. 5 is a diagram showing still another embodiment of the present invention.

In the embodiment shown in FIG. 3, this is the gap β between the left and right sides, and one gap β in the middle. It corresponds to a larger version of . The incident light within the maximum permissible angle of the transparent prisms 51°52.51' and 52' on both sides is
1' and 52' are effectively focused, and the other light is focused on the bottom surface 53.
It is characterized by its ability to pass through. This example is
Suitable for effective use of sunlight. That is, the light focused by the transparent prisms 51°52.51' and 52' is
It can be effectively used by converting it into heat or electrical output, and the rest of the light is transmitted through the bottom, so it can be used for daylighting and moderate heating. Therefore, this embodiment is suitable for use as a building material for windows, greenhouse walls, etc.

In the above embodiments, any transparent refractive medium can be used as the material for the transparent prism, but if the focused light is to be used as heat, a material that has heat resistance and low thermal conductivity may be used. It needs to be small, prevent heat convection, and have a high absorption rate for infrared light. An example of a material that satisfies this condition is silicone resin material.

Note that if the material has a good absorption rate for infrared light, the heat collecting surface does not need to be processed into an expensive selective absorption film, and has great practical advantages in terms of durability and cost reduction.

As explained in detail above, the present invention uses a plurality of transparent prisms that guide incident light having a certain range of incidence angles to a light receiving surface by utilizing silk reflection or specular reflection, which are arranged in multiple stages with gaps. This has great practical advantages, since it is possible to obtain a condensing device with a high condensing ratio with a simple structure, and also to make use of the effective ratio of light at an incident angle that cannot be condensed conventionally.

[Brief explanation of the drawing]

FIG. 1(a) is a schematic diagram showing a condensing device using a transparent prism, FIG. 1(b) is a perspective view thereof, FIG. 2 is a schematic diagram of a condensing device using a prism with a mirror, and FIG. 4 and 5 are schematic diagrams of light condensing devices showing embodiments of the present invention, respectively. In the figure, 11, 21, 31, 32, 41, 42°51.5
2, 51', and 52' are transparent prisms, and 22°43 is a mirror. Also, each suffix a is on the front side, and the suffix b is on the back side.

Claims (1)

[Claims] A condensing device characterized by a plurality of transparent prisms arranged in multiple stages with gaps between them, which guide incident light having an incident angle within a certain range to a light-receiving surface using total reflection or specular reflection.