Flexible or portable closure – partition – or panel – Plural strip – slat – or panel type – Venetian blind type
Reexamination Certificate
1999-08-09
2001-05-08
Purol, David M. (Department: 3634)
Flexible or portable closure, partition, or panel
Plural strip, slat, or panel type
Venetian blind type
C160S236000
Reexamination Certificate
active
06227280
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a Venetian blind type sunshade having a plurality of lamellae which are arranged in parallel with each lamella having substantially plane face elements along a respective longitudinal axis wherein each lamella may reflect received sunlight while maintaining a through-view along the horizontal direction.
PRIOR ART
Known sunshades, such as lamellar Venetian blinds made of vinyl or aluminum, do not both afford protection from the direct glare of sunlight inside rooms and allow selective transmission of light for the entry of daylight so that artificial light inside a room may be dispensed with. Moreover, lamellar Venetian blinds, particularly in a condition of completely screening-off, do not allow any possibility of an optical through-view to the outside, which would be desirable to improve the quality of the living and working environment in the rooms thus screened-off.
Generic screening systems are known which disperse sunlight with optically non-transparent materials used for lamellar Venetian blinds and utilize the fact that, with direct solar irradiation on surfaces of buildings or windows, up to 80% of the irradiating light intensity originates from a solar or circumsolar spatial angle. These sunshade systems, which are mainly made of optically transparent materials, have directionally selective transmissive properties and screen-off the light coming from undesired angles, preferably that from the solar spatial angle. However, these systems are substantially optically transparent for light components from other directions. Examples of such sunshade systems are known, for example, from U.S. Pat. No. 631,220, U.S. Pat. No. 3,255,665 and U.S. Pat. No. 737,979.
Because the angle of solar elevation changes steadily in the course of a year, it is necessary either for such directionally selective sunshade systems to be adapted to the actual position of the sun (so-called “active elements”), or for the directionally selective properties to be so designed that they permanently screen-off a very wide range of spatial angles of the sky (so-called “passive elements”).
One example of active elements is described in the EP 0 090 830, which shows a sunshade designed in the form of lamellae using a material transparent to light. The plurality of lamellae are parallel to each other, and are each rotatable about their respective longitudinal lamella axes have a plane surface facing the sun, the opposite surface having a prismatic structure preferably consisting of prismatic rods aligned in parallel. For effective protection from the sun, the individual surfaces facing the sun must be aligned approximately perpendicularly to the prevailing incident light so that the light rays incident on the individual lamellae of an optically transparent material are reflected back to the outside by total reflection. Although the known sunshade permits the entry of daylight into the interior of a room, it blocks the through-view considerably because of the necessary orientation perpendicular to the sun.
The aspect ratio A/B, which indicates the ratio of the inter-lamellar spacing A between two adjacent lamellae of the Venetian blind to the lamella width B, serves as a geometric index for lamellar Venetian blinds.
FIG. 2
shows a diagram representing, as a percentage, the portion of the area between the lamellar elements which is available for an unrestricted through-view in depending upon the settings of the lamellar elements, as related to the solar elevation angle that varies during the course of a day.
Within
FIG. 2
, “Ref. View” plots the portion of the area which remains between the prismatic lamellae according to the above-described European publication and which can be seen through in the horizontal direction, in dependence on the position of the sun. It can be seen that, with the sun in a high position, the single lamellar elements must be oriented at a smaller angle, whereby the unrestricted through-view between two adjacent lamellar elements becomes larger than in the case of sun positions having only low elevation. “Ref. View,” as shown, is based on an aspect ratio A/B of 1.
Because of the requirement of an orientation of the individual lamellae perpendicular to the incident solar rays, the through-view characteristics become substantially impaired. In order to avoid the disadvantages of an orientation substantially perpendicular to the sun, lamellar structures have been conceived from which the light which is incident obliquely on the lamella surface is also reflected obliquely. Such arrangements are evident from the documents DE 44 42 870 A1 and DE 44 44 509 A1. The lamellae described there for precisely controlling the direct solar irradiation have a sun-facing saw-tooth-like structure which, however, is coated with a metal coating. However, the disadvantage of these known sunshade systems is the strong heating of the metal surfaces, because they absorb between 5 and 15% of the incident energy, depending on the actual design. Moreover, the individual lamellar elements are optically non-transparent because of the metal coating.
Sunshades of large area having a lamella-like structured surface are known, for example, from the publications GB 2 220 025 A and GB 2 170 256 A . Both cases involve facade coverings transparent to sunlight, which are preferably suitable for greenhouses, and deflect the sunlight at a desired angle of incidence into the interior of a greenhouse. Although total reflections occur with a suitable optical arrangement of the optically active surfaces of the sunshades, in the case of FIGS. 2 and 3 of GB 2 170 256, the light is not reflected back in the same direction from which the light is incident on the sunshade. Glare effects in the environment are unavoidable.
BRIEF DESCRIPTION OF THE INVENTION
An object of the invention is to provide a Venetian blind system that substantially allows through-view while substantially reducing glare.
A further object of the invention is further developing a Venetian blind type sunshade having a plurality of lamellae which have substantially plane face elements of elongated configuration, wherein each lamella may be irradiated by the sun at such an angle that a through-view along the horizontal direction is substantially retained, the development being that the characteristics of the view through the sunshade are substantially unimpaired or only slightly impaired while any dazzling or glare effects caused by the sunlight directly incident into the interior of a room are prevented. In particular, the sunshade should not display any self-heating and should be made of an optically transparent material.
According to the invention, a Venetian blind type sunshade having a plurality of lamellae that are arranged in parallel with horizontally extending longitudinal axes and which are rotatable about respective longitudinal axes by means of an adjusting mechanism is designed in such manner that each lamella, or a layer coated on the upper side of the lamella, consists of a material transparent to sunlight and has a cross-section, which is composed of the following face elements: (a) first face elements which are disposed obliquely to the upper side of the lamellae and can receives sunlight approximately perpendicularly; (b) second face elements which are disposed flush with and at an acute angle of about 45° to the first face elements; and (c) a third face element which is disposed to be approximately perpendicular to the second face elements.
In particular, adjacent pairs of first and second face elements have a mutual spacing which, when said first face elements are irradiated approximately perpendicularly by sunlight, permits irradiation by and emission of the sunlight via the first elements with little screening. Moreover, the only optical connections permitted across this spacing are within the thickness between the upper surface and the third face.
The orientation of the surfaces of the optical connecting elements parallel to the third face elements ensures that direct sunlight can leav
Gombert Andreas
Jungjohann Jörg
Willwer Volker
Wirth Harry
Fraunhofer-Gesellschaft zur Forderung der ange-wandten Forschung
Purol David M.
Staas & Halsey , LLP
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