Patent ID: 12209719

DETAILED DESCRIPTION

Optical elements and systems are disclosed in the present disclosure that can be incorporated into buildings to prevent beam sunlight from entering through apertures of the building while allowing diffuse skylight to enter the building through the apertures. The optical system comprises optical elements configured to admit diffuse skylight through an aperture in the building envelope, while reflecting away the beam sunlight incident on the aperture in the building envelope. The apertures can be, for example, windows in walls or skylights in roofs of the building envelope. The optical system works for both windows in the walls and skylights in the roof, with somewhat different configurations for those two parts of the building envelope.

In the following detailed description, for purposes of explanation and not limitation, exemplary, or representative, embodiments disclosing specific details are set forth in order to provide a thorough understanding of an embodiment according to the present teachings. However, it will be apparent to one having ordinary skill in the art having the benefit of the present disclosure that other embodiments according to the present teachings that depart from the specific details disclosed herein remain within the scope of the appended claims. Moreover, descriptions of well-known apparatuses and methods may be omitted so as to not obscure the description of the example embodiments. Such methods and apparatuses are clearly within the scope of the present teachings.

The terminology used herein is for purposes of describing particular embodiments only and is not intended to be limiting. The defined terms are in addition to the technical and scientific meanings of the defined terms as commonly understood and accepted in the technical field of the present teachings.

As used in the specification and appended claims, the terms “a,” “an,” and “the” include both singular and plural referents, unless the context clearly dictates otherwise. Thus, for example, “a device” includes one device and plural devices.

Relative terms may be used to describe the various elements' relationships to one another, as illustrated in the accompanying drawings. These relative terms are intended to encompass different orientations of the device and/or elements in addition to the orientation depicted in the drawings.

It will be understood that when an element is referred to as being “connected to” or “coupled to” or “electrically coupled to” another element, it can be directly connected or coupled, or intervening elements may be present.

Exemplary, or representative, embodiments will now be described with reference to the figures, in which like reference numerals represent like components, elements or features. It should be noted that features, elements or components in the figures are not intended to be drawn to scale, emphasis being placed instead on demonstrating inventive principles and concepts.

FIGS.1A-1Care top cross-sectional views of an optical element1in accordance with a representative embodiment that can be incorporated into an aperture of a building envelope. The optical element1is optically transmissive to diffuse skylight and reflective to beam sunlight. The optical element1comprises an optically clear medium, such as plastic or glass, for example. In accordance with this embodiment, the optical element1has a generally flat surface on one side and a serrated surface on the opposite side, as depicted inFIG.1A. The generally flat surface is on the side that faces away from the building such that exterior light is incident on the flat surface before it is incident on the serrated surface. The side having the serrations faces the interior of the building. In accordance with an embodiment, the serrations are linear, creating a uniform cross section along the length of the optical element1. In an example, the serrated-surface planes are at an angle of approximately 450 to the plane of the flat surface on the opposite side of the glazing element. The inventive principles and concepts are not limited to this angle being approximately 45°. The angle typically ranges between about 30° and 60°. The serrations are symmetric in the embodiment shown inFIGS.1A-1C, but they are not required to be symmetric.

FIG.1Bdepicts the manner in which the serrations reflect beam sunlight.FIG.1Bshows the optical behavior for rays incident on the flat side of the optical element. The beam sunlight rays are incident in a plane perpendicular to the flat side of the optical element1and parallel to the length-wise direction of the serrations on the other side of the optical element1. In this example in which the serrated-surface planes are at an angle of approximately 45° to the plane of the flat surface on the opposite side, the incident light on the serrated-surface planes is reflected by total internal reflection, as depicted inFIG.1B. Therefore, substantially all of the beam sunlight is reflected and does not pass through the aperture in which the optical element1is incorporated or installed.

FIG.1Cdepicts the manner in which the flat surface and the serrated surface pass diffuse skylight. The rays of diffuse skylight and not incident in a plane perpendicular to the flat side of the optical element and parallel to the serrations on the other side of the optical element. Therefore, these rays are not reflected by total internal reflection, but rather, they pass through the flat surface, are refracted to some extent and continue through the serrated surface, which again refracts the light to some extent. All, or substantially all of the diffuse skylight is transmitted through the optical element.

To be effective in reflecting beam sunlight away from the building, the optical element1should be rotated continuously or periodically, tracking the sun in such a manner that the beam sunlight is incident on the flat side of the optical element, and in a plane that is both substantially perpendicular to the flat side of the optical element1and substantially parallel to the direction of the serrations.

The optical element typically has one of two general configurations:1. A series of optical slats with:the serrations running parallel to the long direction of the slata mechanism being provided to rotate each slat about an axis parallel to the long direction of the slat.2. A glazing element, that rotates in its plane about an axis perpendicular to its plane.

As a glazing element that is part of the overall aperture glazing assembly, the optical element can encapsulate a still layer of air (or other insulating gas, such as Argon), thereby enhancing the thermal integrity of the overall aperture glazing assembly. As a glazing element that is part of the overall aperture glazing assembly, the optical element can also provide additional surfaces for a low-E coating, which can help suppress thermal radiation transfer through the aperture glazing assembly.

Serrated optical elements have been used in:Fresnel lenses in lighthouses and ships.Light diffusing elements in fluorescent fixtures, in which capacity they mainly serve the purpose of transmitting light while obscuring, or blurring, the image of the fluorescent lamps and other parts of the fixture that might be regarded as unsightly.Optical elements or systems intended to redirect light entering a building aperture. Such optical elements or systems did not track the sun movement.
Total internal reflection in optically dense material has been used in:Binoculars, as a way of extending the light pathway, thereby facilitating higher magnification of the image of the object being observed.Fiber optics, to contain light being transmitted from one location to another for purposes of data transmission.The Prism Light Guide, invented by Lorne Whitehead (U.S. Pat. No. 4,260,220), to transmit light from one location to another for purposes of illuminating building interiors.A Cyro glazing product, as a way of rejecting some portion of the beam sunlight incident on an aperture in a building. The Cyro product did not track the sun, which means that it only worked at limited angles of the beam sunlight.

What has not been proposed, and what is the subject of the present disclosure, are uses of optical elements or systems that track the sun to facilitate the use of total internal reflection to maximize the rejection of beam sunlight while still admitting substantial amounts of diffuse skylight and diffuse light reflected off of exterior surfaces, such as the ground.

FIG.2is a top view of a circular optical element2mounted in a circular aperture in accordance with another representative embodiment, with the optical element2being rotated about a vertical axis of rotation at the center of the optical element2to track the sun.FIG.3is a top view of a circular optical element3mounted in a circular aperture in accordance with another representative embodiment that is identical to the configuration shown inFIG.2except that the optical element shown inFIG.3has a region filled with still air in between the serrated surface and an interior glazing.FIG.4is a top view of a circular optical element4mounted in a circular aperture in accordance with another representative embodiment that is identical to the configuration shown inFIG.3except that the interior glazing is prismatic or diffusive to disperse the diffuse skylight into the interior of the building.

The optical elements1-4shown inFIGS.1-4, respectively, having the serrated surfaces used in conjunction with a rotating mechanism within a building aperture, or associated with a building aperture, reflect away beam sunlight while admitting diffuse skylight and diffuse light reflected off terrain or other surfaces external to the building.

In accordance with the representative embodiment shown inFIGS.1A-1C, the optical element1comprises a flat sheet having a flat surface on one side and a serrated surface on the opposite side. In accordance with the representative embodiment shown inFIGS.2-4, the circular optical element2-4comprises a generally circular sheet having a flat surface on one side, a serrated surface on the opposite side, and an exterior glazing. The generally circular sheet rotates about an axis that is perpendicular to the sheet and located at the center of the optical element. The optical elements3and4further comprise interior glazing surfaces and can include other features, such as a pocket for still air in between the serrated surface and the interior glazing surface, and/or prismatic or diffusive elements formed on or in the interior glazing surface.

The circular optical elements2-4can be configured to fully protect the circular aperture against all incoming beam sunlight. Alternatively, the circular optical elements2-4can be configured to partially protect a non-circular aperture, with beam sunlight penetrating through the unprotected parts of the aperture lying outside the circular optical elements2-4. The optical elements1-4can provide additional surfaces for a low-E coating, which can help suppress thermal radiation transfer through the aperture glazing assembly.

If desired, the optical elements1-4can be rotated in such a way so as to intentionally admit some amount of beam sunlight on occasion.

When properly sealed around the boundary of the building aperture, the optical element can work in conjunction with the exterior of the building. For example, weather-resisting glazing can be part of, or used in conjunction with, the optical element to encapsulate a still layer of air (or other insulating gas, such as Argon), as shown inFIGS.3and4, thereby enhancing the thermal integrity of the overall aperture glazing assembly.

FIG.5Ashows the flat optical element1shown inFIGS.1A-1C.FIGS.5B and5Cshow an alternative configuration for the optical element1in accordance with an embodiment in which the optical element5is split into alternating, offset strips to facilitate admitting more off-axis diffuse light and dispersing the light more uniformly around the building interior. As shown inFIGS.5B and5C, the optical element5includes vertical portions that are absent of the serrations and that are optically transmissive, whereas the other portions of the optical element include the serrated surfaces that act in the manner described above to reflect beam sunlight while passing on-axis diffuse skylight. The vertical voids all off-axis diffuse light to pass through the optical element5into the interior of the building.

FIG.6shows a representative embodiment of the optical element6that has a configuration that includes the offset strips shown inFIGS.5B and5C, but further comprises additional horizontal and vertical portions of optically transparent material that encapsulate more layers of still insulating air and provide additional stiffness for mechanical stability.

FIG.7shows an alternative configuration for the optical element1in accordance with an embodiment in which the serrated surface7of the optical element is corrugated to add stiffness.FIG.8shows an alternative configuration of the optical element shown inFIG.7in which sheets of material have been added on each side of the serrated surface8to encapsulate a still air layer for thermal resistance and to add stiffness in both directions by creating a two-way stressed skin panel that is beam-like for spanning in one direction and truss-like for spanning in the other direction.

FIG.9Ashows a configuration of the optical element9in accordance with a representative embodiment that is similar to the configuration of the optical element2shown inFIG.2, with the variation that the optical element9is arched out of the plane of the originating circle.FIG.9Bshows a three-dimensional (3-D) rendering of the optical element9shown inFIG.9AandFIG.9Cshows a 3-D cross-sectional view of the optical element9. Arching of the circular sheet having the serrated surface creates vertical voids similar to what was described above with reference toFIG.5Bthat are absent of the serrations to allow diffuse light to pass through the vertical portions into the interior of the building.

FIG.10Ashows a configuration of the optical element10in accordance with a representative embodiment that is identical to the optical element9shown inFIG.9A, except the vertical voids shown inFIG.9Aare covered with optical transmissive vertical sheets, similar to the configuration of the optical element5shown inFIG.5C.FIG.10Bshows a 3-D rendering of the optical element10shown inFIG.10AandFIG.10Cshows a 3-D cross-sectional view of the optical element10. As with the vertical voids shown inFIGS.9A-9C, the optically-transparent vertical sheets allow diffuse light to pass into the interior of the building, but unlike the vertical voids, the vertical sheets encapsulate still air between the surfaces and the exterior glazing for insulation.

FIG.11shows a configuration of the optical element11in accordance with a representative embodiment that is similar to the configuration shown inFIG.10Ain that the optical element is arched out of the plane of the originating circle in a gradual, step-wise manner, producing a generally domical shape. InFIG.11, the serrations and the thickness of the optical element11have been exaggerated in size to make them more visible. In reality, the serrations and the thickness of the domical optical element11would be much smaller relative to the overall dimensions of the domical optical element11. In this embodiment, the serrations conform to the domical shape. Diffuse light penetrates through vertical panes of the serrations while the beam sunlight is reflected by the angled faces of the serrations. Conforming the serrations to the domical configuration does not change the optical behavior of the optical system, but improves structural integrity at the cost of increased manufacturing complexity.

FIG.12shows an optical-element sunshade system12in accordance with a representative embodiment that is suitable for linear apertures and that uses single-axis tracking on a rotating mechanism. The system12comprises a plurality of optical elements coupled to separate mounts that are rotated by the rotating mechanism to track the sun. The optical elements can have any of the configurations described above, for example. The optical-element sunshade system12comprises a plurality of highly reflective surfaces, where adjacent highly reflective surfaces are separated from one another by daylight apertures that are covered with insulated glazing surfaces. Diffuse skylight that is not incident on the optical elements that track the sun passes through the insulated glazing and the daylight apertures into the interior of the building. Beam sunlight that that is not incident on the optical elements is incident on the highly reflective surfaces and is reflected by the highly reflective surfaces. The optical system12includes a protective upper glazing surface. The entire optical system12operates as an optical element sunshade that is installed on the top surface of the building.

Localized apertures, such as, for example, circular openings in the roof, can be shaded by circular or elliptical optical sunshade systems that follow the sun using a double-axis, tracking mechanism.FIG.13shows a remote optical sunshade system13designed for a circular aperture. The system13uses an Equatorial Mount to adjust the location of the sunshade system13in space in such a manner as to shade the aperture and to adjust the orientation of the sunshade system13based on the time of the year so that the normal to the plane of the sunshade system13is always pointing toward the Sun. In the mount shown inFIG.13, the optical-element sunshade13aslides along the Arc Beam13bto account for seasonal changes in sun position and rotates about an axis parallel to the earth's rotational axis to account for diurnal changes in sun position. This mounting system is similar to an Equatorial Mount for Celestial Telescopes.

As an alternative to the Equatorial Mount shown inFIG.13, the remote optical-element sunshade13for the circular roof aperture can also be positioned in space and oriented toward the sun using an Altitude-Azimuth mount.

In situations where electricity generation is desired, the optical element(s) in the sunshade12or13can be replaced by concentrating Photo-Voltaic Cells, which can be highly concentrating, since the device is always pointed into the Sun. The heat generated by the Photo-Voltaic Cells does not significantly impact the building thermal loads, since the Cells are thermally detached from the building and remote from the building envelope. In addition, because the optical elements of all of the embodiments described above track the Sun, they can be configured with solar cells to harvest the energy of the Sun such that the optical elements do not increase the electrical load of the building or facility, or at least to offset the additional electrical load on the building or facility. In addition, the electrical energy generated by the Photo-Voltaic Cells can be used for any purpose, including, but not limited to, driving the tracking mechanism.

It should be noted that all variations of the optical element and optical systems described above can be utilized in all apertures in all parts of the building envelope, including all slopes, from horizontal to vertical, and all azimuthal orientations, with the caveat that the rotational algorithm will vary with the tilt and orientation of the aperture and the latitude of the building location.

FIG.14Ashows the optical system14in accordance with another representative embodiment comprising an array of parallel optical-element slats14a, each of which can comprise the optical elements having serrations on one side similar to the serrations shown inFIGS.1A-1C. In accordance with this embodiment, the long dimension of the optical-element slats14ais parallel to the serrations, and each slat14ais able to rotate about an axis parallel to the serrations, as shown inFIG.14A. The slats14aare rotated to track the Sun so that the serrations reflect the beam sunlight by total internal reflection while passing the diffuse light, as described above with reference toFIGS.1A-1C.FIG.14Bshows the optical behavior of the optical system shown inFIG.14A.

FIG.15Ashows the optical system15in accordance with another representative embodiment that is a variation of the embodiment shown inFIG.14A.FIG.15Bshows the optical behavior of the optical system shown inFIG.15A. The system15comprises optical-element slats15athat have been stiffened by giving them an angular cross-sectional shape. In accordance with this representative embodiment, each slat15ahas first and second slat portions15band15cthat are coupled to one another at a 90° angle. The slats15aare rotated as shown to track the sun so that the beam sunlight rays are always incident perpendicular to left side of the serrations of the slat portions15band to the right side of the serrations of slat portions15cat a given time of the day, resulting in total internal reflection of the beam sunlight.

FIG.16Ashows the optical system16in accordance with another representative embodiment that is a variation of the embodiment shown inFIG.15A.FIG.16Bshows the optical behavior of the optical system shown inFIG.16A. The system16comprises optical-element slats16athat have been stiffened by giving them a cross-sectional shape of an angular tube. In accordance with this representative embodiment, each slat16ahas first and second slat portions16band16cand a stiffening portion16d, all coupled together to form the cross-section of a triangular tube. The slats16aare rotated as shown to track the sun so that the beam sunlight rays are always incident perpendicular to left side of the serrations of the slat portions16band to the right side of the serrations of slat portions16cat a given time of the day, resulting in total internal reflection of the beam sunlight.

The optical-element slats shown inFIGS.14A-16Bcan be arrayed in a plane parallel to the plane of the aperture. For example, for a vertical aperture, the optical-element slats can be suspended vertically, similarly to vertical blinds commonly manufactured for windows in buildings. In this configuration, the slats can either hang freely under gravity (as is common for vertical blinds) or be aligned more forcefully with constraints at the bottom of each of the slats.

With proper support, the array of optical-element slats can be sloped at any angle to make the plane of the array parallel to the plane of the aperture, regardless of the slope of the aperture. For example, the optical elements can be arrayed in a horizontal plane for a horizontal roof aperture or in a sloped plane for a sloped roof aperture.

The array of optical-element slats can be mounted in any of the following locations: external to the outermost layer of glazing in the aperture; internal to the innermost layer of glazing in the aperture; and between layers of glazing, where it is protected against wind, snow, ice, rain, and dirt (for example, in the interstitial volume in a double-envelope façade).

The axes of rotation of the optical-element slats can be arrayed in a plane NOT parallel to the plane of the aperture. For example, for a vertical aperture, the array of optical-element slats can be mounted above the aperture, projecting out from the façade of the building, in an Awning Configuration, which serves to shade the glazing below while still affording a view through the glazing that is not obscured by the optical distortion of the Optical-Element Slats.

The array of optical-element slats can be sloped at an angle to strike a balance between protecting the glazing below the array from excess sunlight while still allowing some view through that glazing that is not obscured by the optical distortion of the optical-element slats.

The array of optical-element slats can be sloped at any angle to reflect sunlight back toward the Sun, to avoid having the reflected sunlight cause thermal overload or glare for adjacent buildings.

Versions of the optical elements can be configured to send beam sunlight back toward the Sun, thereby eliminating all negative impacts of adjacent buildings. As an example, seeFIG.13, in which the normal to the optical-element sunshades are always facing directly toward the Sun, resulting in the incident sunlight being reflected directly back toward the sun.

The flat circular optical elements shown inFIGS.2and3can be mounted in various locations, including, for example: external to the outermost layer of glazing in the aperture; between layers of glazing in a double-envelope building, where the optical element and its support mechanism are protected against wind, snow, ice, rain, and dirt; and in the aperture in the building envelope, with hemispherical glazing outside to protect it against wind, snow, ice, rain, dirt from above and hemispherical glazing inside it to protect it from dirt from below; internal to the innermost layer of glazing. In this mode, a mechanism can be incorporated to cause the optical element to deviate from a plane, so that the sunlight can be spread over the ceiling to brighten and warm the space during the colder months of the year.

As previously noted, beam sunlight reflected back toward the Sun will not negatively impact any adjacent buildings. The only humans who could be negatively impacted are airplane pilots. At typical jet speeds, the transit time for a jet plane over a 10 ft diameter roof aperture will be on the order of a 1 hundredth of a second. Furthermore, at the scale of heights at which jet planes normally fly, a 10-ft-diameter reflector will act optically like a pin-hole in a pin-hole camera, meaning that the effective luminosity of the 10-ft-diameter reflector will be negligible. In other words, the reflective optical elements represent a negligible effect on pilots. A large lake will have a much greater impact on the pilot's vision. As an additional benefit to this system, the heat content of the solar radiation reflected back toward the sun will be lost from the earth's ecosphere, which means that it does not contribute to global warming.

It should be noted that the inventive principles and concepts have been described with reference to representative embodiments, but that the inventive principles and concepts are not limited to the representative embodiments described herein. Although the inventive principles and concepts have been illustrated and described in detail in the drawings and in the foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art, from a study of the drawings, the disclosure, and the appended claims.