Method and device for dousing sunlight with a seasonal effect

4,357,074

06/173,146

July 28, 1980

A dousing or light blocking method and device for controlling the transmission of sunlight includes a plate of transparent material, having one flat, vertical or nearly vertical, surface and an opposite at least partially inclined surface, the latter facing the sun. The plate is oriented and located with respect to the sun in a predetermined period of the sun path, so as to prevent direct sunlight from getting through the plate in a desired and predetermined year season or period without interfering with the transmission of diffused light.

Nardini, Gian V. (22060 Carimate (Como), ITX)

I claim

1. A method for seasonally dousing sunlight, comprising

forming a transparent douser plate of a material having an index of refraction greater than unity and with a critical angle of internal reflection;

forming at least one first plane surface on said transparent douser plate;

forming at least one second plane surface on said transparent douser plate;

said at least one first plane surface and said at least one second plane surface being inclined at an inclined angle with respect to each other;

said index of refraction and said inclined angle being effective to cause light entering said douser plate from at least some directions through said first plane surface to become incident onto said second plane surface at angles equal to or exceeding said critical angle;

positioning said second plane surface substantially vertical and disposing said at least said one first plane surface facing the sun substantially at noon time and at said inclined angle with respect to said second plane surface whereby the sun altitude corresponding to the said directions which produce said critical angle for direct sunlight is a limiting altitude of the sun, and direct sunlight is blocked for sun altitudes above said limiting value and direct sunlight is transmitting through said douser plate for at least some sun azimuths for sun altitudes below said limiting value.

2. The method of claim 1, wherein the inclined angle is identified as b, and the angle b is chosen to satisfy the following relationship [equation included]

where

n=index of refraction

c=critical angle

a=limiting altitude of the sun.

3. A fixed douser for seasonally dousing sunlight, comprising

a transparent douser plate of a material having an index of refraction greater than unity and, as a result, a critical angle of total internal refraction;

said transparent douser plate having at least one first plane surface and one second plane surface, said first plane surface and second plane surface being inclined at an inclined angle with respect to each other;

said index of refraction and said inclined angle being effective to cause the light entering said douser plate from at least some directions through said first plane surface to become incident onto said second plane surface at angles equal to or exceeding said critical angle;

said second plane surface being substantially vertical; and

said at least said one first plane surface facing the sun substantially at noon time and being disposed at said angle with respect to said at least said one second plane surface, whereby the sun altitude corresponding to said directions which produce said critical angle for direct sunlight is a limiting altitude of the sun, and direct sunlight is blocked for sun altitudes above said limiting value and direct sunlight is transmitted through said douser plate for at least some sun azimuths for sun altitudes above said limiting value and direct sunlight is transmitted through said douser plate for at least some sun azimuths for sun altitudes below said limiting value.

4. A fixed douser according to claim 3, wherein said inclined angle is identified a b and said angle b satisifies the following relationship

5. A fixed douser according to claim 4, wherein said at least one first plane surface includes a plurality of first plane surfaces and said first plane surfaces are all parallel to one another and are bounded by substantially horizontal parallel lines.

6. A fixed douser according to claim 5, wherein said plurality of first plane surfaces define a plurality of adjacent prismatic elements or ribs and each rib has a solid corner between its first plane surface and a third surface.

7. A fixed douser according to claim 6, wherein said third surface of each of said prismatic elements or ribs is a plane, so that each of said prismatic elements or ribs has a substantially triangular cross section.

8. A fixed douser according to claim 7, wherein a solid angle between faces of said first and third plane surfaces in each of said prismatic ribs is at least as great as a sum of said critical angle and 90 degrees.

9. A fixed douser according to claim 7, wherein all said third plane surfaces are parallel to the direction to the sun at said limiting altitude.

10. A fixed douser according to claim 6, wherein said douser plate includes a ratio of minimum thickness of from about 1 to 2 to about 9 to 10.

11. A fixed douser according to claim 10, wherein said ratio is 5 to 6.

12. A fixed douser according to claim 3, wherein said at least one first plane surface includes a plurality of plane surfaces each forming with said second plane surface a prism, all of said prisms having the same orientation.

13. A fixed douser according to claim 3, wherein said limiting altitude is equal to the altitude reached by the sun on dates in spring and fall corresponding to dates when changeover between artificial winter heating and summer non-heating is required.

14. A fixed douser according to claim 13, wherein said limiting altitude is at least 50 degrees.

350/259; 350/265

G02B 1700; G02B 2700

2993409 July 1961 Boyd
3255655 June 1966 Weiher et al.
3471221 October 1969 Seeger
4227774 October 1980 Corll

edspgr.04357074