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FIELD 
       [0001]    The present invention relates to devices and methods for controlling solar radiation and more particularly, to shades and reflectors for controlling and redirecting sunlight that enters a building through a window or other feature of a building that admits sunlight to the interior of the building. 
       BACKGROUND 
       [0002]    Sunlight that enters a building frequently has beneficial lighting and heating effects but can also be objectionable if it raises the temperature inside the building to an uncomfortable level, causes sun damage to building contents or creates excessively bright or uneven illumination or glare. From the energy efficiency perspective, sunlight has the capacity to decrease energy usage by providing natural heat and light, thereby diminishing the need for energy-consuming artificial heating and lighting. In hot climates, however, solar radiation may produce unwanted heat that places additional demands on air conditioning equipment to reduce indoor temperatures. Furthermore, sunlight is sometimes too intense, e.g., to use for illumination of reading materials, and focused in areas of a building that are not optimal or useable due to position or concentration of the solar radiation. Indoor and outdoor shades of various kinds are known which block sunlight in whole or part to control the amount of solar radiation that enters a building. Apparatus are also known for use in redirecting light from its natural path, e.g., to illuminate areas of a building that would otherwise not be illuminated in the same manner by the incoming solar radiation. Notwithstanding the existence of known types of shades and light reflectors, alternative apparatus for controlling sunlight remain desirable. 
       SUMMARY 
       [0003]    The disclosed subject matter relates to a light shelf for controlling solar radiation that impinges on a building. The light shelf has a panel capable of interacting with light, a stationary mounting element capable of occupying a fixed position relative to the building, and a moveable mounting element capable of coupling to the stationary mounting element and the panel and moveable between a plurality of positions relative to the stationary mounting element for selectively supporting the panel at a plurality of positions relative to the building. 
         [0004]    In accordance with another aspect of the disclosure, the stationary mounting element includes a track along which the moveable element moves. 
         [0005]    In accordance with another aspect of the disclosure, the moveable element includes a bracket moveable on the track and a retaining element capable of retaining the bracket at a selected one of the plurality of positions. 
         [0006]    In accordance with another aspect of the disclosure, the stationary mounting element includes a plurality of tracks and the moveable element includes a pair of brackets, each bracket of the pair moveable along a corresponding one of the plurality of tracks. 
         [0007]    In accordance with another aspect of the disclosure, each bracket of the pair of brackets is separately moveable relative to the other bracket of the pair. 
         [0008]    In accordance with another aspect of the disclosure, at least one of the brackets includes a pivot coupling interposed between the panel and the corresponding track allowing the panel supported by the at least one bracket to tilt. 
         [0009]    In accordance with another aspect of the disclosure, the panel tilts on the pivot coupling when one of the brackets of the pair is positioned at a higher elevation relative to the other bracket of the pair. 
         [0010]    In accordance with another aspect of the disclosure, both brackets of the pair of brackets has a pivot coupling. 
         [0011]    In accordance with another aspect of the disclosure, the pair of brackets may be moved conjointly on corresponding tracks of the plurality of tracks to selectively position the panel at one of a plurality of elevations relative to the building. 
         [0012]    In accordance with another aspect of the disclosure, the brackets are moveable relative the tracks by a motor. 
         [0013]    In accordance with another aspect of the disclosure, the brackets are moveable relative the tracks manually. 
         [0014]    In accordance with another aspect of the disclosure, the panel includes a plurality of panel elements, at least one panel element moveable relative to another of the panel elements between at least first and second positions, the plurality of panel elements conjointly defining the dimensional extent of the light shelf. 
         [0015]    In accordance with another aspect of the disclosure, the plurality of panel elements have a flat, planar configuration, the at least one moveable panel element stacked in parallel and moving parallel to the another of the panel elements when moving from the first position to the second position. 
         [0016]    In accordance with another aspect of the disclosure, the first position is a retracted position and the second position is a deployed position, the retracted position resulting in the light shelf having a smaller dimensional extent relative to the dimensional extent in the deployed position. 
         [0017]    In accordance with another aspect of the disclosure, the another of the panel elements has an internal hollow at least partially accommodating the at least one moveable panel element, which telescopes into and out of the another panel element to move between the retracted and deployed positions. 
         [0018]    In accordance with another aspect of the disclosure, the movement of the at least one moveable panel element is by a motor. 
         [0019]    In accordance with another aspect of the disclosure, the movement of the at least one moveable panel element is manual. 
         [0020]    In accordance with another aspect of the disclosure, the retainer element is at least one of a clamp, a pin and detent, a screw drive, a pinion gear and a motor. 
         [0021]    In accordance with another aspect of the disclosure, coupling of the moveable mounting element to the panel selectively permits the panel to be positioned at a selected side-to-side off-set relative to the stationary element. 
         [0022]    In accordance with another aspect of the disclosure, a light shelf for controlling solar radiation that impinges on a building, has a panel capable of interacting with light, the panel including a plurality of panel elements, at least one panel element moveable relative to another of the panel elements between at least first and second positions, the plurality of panel elements conjointly defining the dimensional extent of the light shelf. The light shelf has a stationary mounting element capable of occupying a fixed position relative to the building, and a moveable mounting element capable of coupling to the stationary mounting element and the panel and is moveable between a plurality of positions relative to the stationary mounting element for selectively supporting the panel at a plurality of positions relative to the building. 
         [0023]    In accordance with another aspect of the disclosure, the stationary mounting element includes a pair of tracks and the moveable element includes a pair of brackets, each bracket of the pair moveable along a corresponding one of the pair of tracks and capable of engaging the track at a plurality of positions to retain the bracket at a selected one of the plurality of positions, each bracket of the pair of brackets capable of moving separately relative to the other bracket of the pair, at least one of the brackets including a pivot coupling interposed between the panel and the corresponding track allowing the panel supported by the at least one bracket to tilt. 
         [0024]    In accordance with another aspect of the disclosure, the plurality of panel elements have a flat, planar configuration, the moveable panel element stacked and moving in parallel to another panel element when moving from the first position to the second position, the first position being a retracted position and the second position a deployed position, the retracted position resulting in the light shelf having a smaller dimensional extent relative to the dimensional extent in the deployed position, the another panel element having an internal hollow at least partially accommodating the moveable panel element, the moveable panel element telescoping into and out of the hollow between the retracted and deployed positions. 
         [0025]    In accordance with another aspect of the disclosure, the light shelf has a pair of opposed frame elements, each of which have at least one slot, the moveable panel element capable of being slideably received in the at least one slot of opposed frame elements and of moving from the first position to the second position, the first position being a retracted position and the second position a deployed position, the retracted position resulting in the light shelf having a smaller dimensional extent relative to the dimensional extent in the deployed position, the another panel element being held between the opposed frame elements. 
         [0026]    In accordance with another aspect of the disclosure, the light shelf has a pair of opposed frame elements, each having a pair of rotatable pulleys and a belt mounted on the pair of pulleys, wherein the moveable panel element is attached at one end to a first belt of the pair of belts and attached at another end to a second belt of the pair of belts and wherein the another panel element is attached at one end to a first belt of the pair of belts and attached at another end to a second belt of the pair of belts, the attachment of the moveable panel element to the pair of belts being offset from the attachment of the another panel element to the pair of belts, the belts being moveable on the pulleys to move the moveable panel element and the another panel element relative to one another to change a dimensional extent of the light shelf relative to the solar radiation. 
         [0027]    In accordance with another aspect of the disclosure, the light shelf has a motor for adjusting at least one of the position and conformation of the light shelf and a sensor for sensing at least one of the ambient brightness and temperature, a microprocessor coupled to the sensor to receive data generated by the sensor, the microprocessor programmed to respond to the data by generating control signals to the motor to cause the light shelf to adjust. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    For a more complete understanding of the present invention, reference is made to the following detailed description of exemplary embodiments considered in conjunction with the accompanying drawings. 
           [0029]      FIGS. 1-4  are perspective views of a light shelf in accordance with embodiments of the present disclosure and in a variety of positions. 
           [0030]      FIGS. 5-7  are diagrams illustrating selected positions of the light shelf of  FIGS. 1-4  and the interaction of same with solar radiation/light. 
           [0031]      FIG. 8  is an enlarged perspective view of the light shelf of  FIG. 4 . 
           [0032]      FIG. 9  is an elevational view of a bracket and track in accordance with an embodiment of the present disclosure. 
           [0033]      FIG. 10  is a cross-sectional view of the apparatus of  FIG. 9  taken along lines  10 - 10  and looking in the direction of the arrows. 
           [0034]      FIG. 11  is an elevational view of a bracket and track in accordance with an alternative embodiment of the present disclosure. 
           [0035]      FIG. 12  is a cross-sectional view of the apparatus of  FIG. 11  taken along lines  10 - 10  and looking in the direction of the arrows. 
           [0036]      FIG. 13  is an elevational view of a bracket and track in accordance with an alternative embodiment of the present disclosure. 
           [0037]      FIG. 14  is a cross-sectional view of the apparatus of  FIG. 13  taken along lines  10 - 10  and looking in the direction of the arrows. 
           [0038]      FIG. 15  is an elevational view of a bracket and track in accordance with an alternative embodiment of the present disclosure. 
           [0039]      FIG. 16  is a cross-sectional view of the apparatus of  FIG. 15  taken along lines  10 - 10  and looking in the direction of the arrows. 
           [0040]      FIG. 17  is an elevational view of a bracket and track in accordance with an alternative embodiment of the present disclosure. 
           [0041]      FIG. 18  is a cross-sectional view of the apparatus of  FIG. 17  taken along lines  10 - 10  and looking in the direction of the arrows. 
           [0042]      FIG. 19  is front view of a deployment mechanism in accordance with an embodiment of the present disclosure. 
           [0043]      FIGS. 20 and 21  are side views of the apparatus of  FIG. 19  showing the deployed and retracted positions, respectively. 
           [0044]      FIG. 22  is a perspective view of a light shelf in accordance with an alternative embodiment of the present disclosure. 
           [0045]      FIG. 23  is a sequence of schematic side views of the apparatus of  FIG. 22  in two different positions. 
           [0046]      FIG. 24  is a perspective view of a light shelf in accordance with an alternative embodiment of the present disclosure. 
           [0047]      FIG. 25  is a sequence of schematic side views of the apparatus of  FIG. 24  in two different positions. 
           [0048]      FIG. 26  is a diagram of components for controlling a light shelf in accordance with an alternative embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0049]      FIG. 1  shows a light shelf  10  with a first panel  12  positioned relative to window frame  14  for controlling solar radiation that passes through window  16 . The window frame  14  may be provided with a pair of tracks  18 ,  20  for adjustably supporting brackets  22 ,  24  that hold the first panel  12  in a selected position. The support brackets  22 ,  24  may engage the tracks  18 ,  20  via manually actuated clamps, detents, friction locks or slide locks. Alternatively, the brackets  22 ,  24  may have associated motors with pinion gears for engaging a rack gear parallel with the tracks  18 ,  20 . Alternatively, the brackets  22 ,  24  may be positioned by rotatable helices (screw) drives provided within tracks  18 ,  20 . In this later case, the brackets  18 ,  20  may be provided with apertures or forks that engage the helices, such that rotating a helix in a first direction results in the associated bracket going up and going down when the helix is turned in the other direction. As another alternative, the brackets  22 ,  24  may be moved by a linear motor. The brackets  22 ,  24  may be independently moved and may be moved in the same direction or opposite directions relative to the other. 
         [0050]      FIG. 1  shows that the first panel  12  may be positioned at a first height H 1  relative to the bottom of the window frame  14 .  FIG. 2  shows that the first panel  12  may be lowered to another height H 2 , or positioned at any other selected height relative to window  16 , in order to change the shading provided, to position the first panel  12  to be exposed to more or less solar radiation R, or to adjust the angle of reflection of the solar radiation RR reflected from the light shelf  12  (see  FIGS. 5 and 6 ). The supporting brackets  22 ,  24  may feature pivot mounts  26  that enable the angular orientation of the first panel  12  to be adjusted, e.g., by positioning the supporting brackets  22 ,  24  at different heights on tracks  18 ,  20 , as shown in  FIG. 3 , which shows a tilt angle A relative to the horizontal. As shown in  FIG. 2 , the first panel  12  may be held on one side to the bracket  24  by a capped pin  30  extending from an upper surface  32  of bracket  24 , the cap of which is captured in a slotted plate  34  attached to the bottom surface of the first panel  12 . This type of connection allows the first panel  12  to slide relative to the bracket  24  to assume different angles A and to accommodate the associated different distances between brackets  22 ,  24 , when the panel  12  is moved to different angular orientations relative to the horizontal. This type of sliding connection may also be implemented at the interface between the first panel  12  and the bracket  22 . As a further alternative, the side-to-side sliding position of the panel  12  relative to the brackets  22 ,  24  may be controlled by a manual or motor-driven gear train, which can be used to position the panel  12  at a desired offset relative to the window frame  14 , as shown in dotted lines. The panel  12  may be extended sideways to different extents and in both directions. While the foregoing embodiment has been explained in terms of an apparatus utilizing a window frame  14  having tracks  18 ,  20 , etc., it should be understood that the light shelf  10  may constitute an assembly, e.g., having a frame like  14  and/or tracks  18 ,  20  that is retrofitable to an existing window frame, wall or other structural surface or member proximate an opening in a structure/building that admits light into the structure, e.g., by fastening the light shelf  10  by screws, bolts, welding, adhesives, etc. 
         [0051]      FIG. 3  illustrates that the light shelf  10  may assume a tilted orientation relative to the horizontal, viz., at tilt angle A. Radiation R impinging upon the first panel  12  is reflected off at an angle RA as reflected radiation RR, i.e., towards one side or the other of the window  16 , as determined by the angle A. 
         [0052]      FIGS. 4 and 8  show an embodiment of the present disclosure wherein the first panel  12  is hollow and accommodates a second panel  36  which telescopes into the hollow first panel  12 . The degree of deployment of the second panel  36  from the first panel  12  may be variable and/or controlled by an electric motor, e.g., acting through a rack and pinion, or by a spring which urges the second panel  36  to a deployed position and which acts against a control cord wound on a motor-driven take-up spool or other conventional motor/actuator positioning mechanisms. In the instance of a second panel  36  that is resiliently urged to a deployed position, the second panel  36 , can absorb force that is exerted thereon, e.g., by a person or object that inadvertently bumps into the second panel  36  without breaking The first and second panels  12 ,  36  may be made from metal, such as aluminum, or from plastics, such as a polypropylene honeycomb panel or a multiwall polycarbonate panel with aluminum or mylar skin on the reflective surface. 
         [0053]      FIG. 5  diagrammatically shows a building  38  having a window  16  (shown in dotted lines), with the sun S casting radiation R through the window  16 . Some of the solar radiation travels to bright area B 1 , which could be a floor, a desk or any other type of surface. Another portion of the radiation R is intercepted by first panel  12  of light shelf  10  (see  FIGS. 1-4 ) at height H 3  relative to the floor and is at least partially reflected RR from the first panel  12  to an area W 1  on wall W, or if the room were larger, to area C 1  on ceiling C. The interception of light by first panel  12  results in a shaded area D 1 . The reflected light RR impacting W 1  or C 1  diffuses outwardly to a degree depending upon the type of surface at W 1  or C 1 , e.g., as defined by color and texture. Similarly, the surface of first panel  12  from which light is reflected impacts the direction and amount of light reflected there from. A light diffuser (not shown) such as a translucent panel or frosted glass pane may be interposed between the first panel  12  and the impact area W 1  or C 1  to diffuse the reflected light RR before it reaches the wall W or ceiling C. 
         [0054]      FIG. 6  shows the building  38  with window  16  and the sun S in the same position as in  FIG. 5 , casting radiation R through the window  16 . The first panel  12  of light shelf  10  has been positioned at a different height H 4  relative to the floor, resulting in differently positioned and sized shaded area D 2  and bright area B 2 . The reflected light RR has a width X 1  and impacts the wall W at area W 2 , which is lower on the wall W than W 1 . As can be appreciated from  FIGS. 5 and 6 , the adjustable light shelf  10  can be used to selectively control solar radiation to shade and illuminate different areas of a structure  38  having a window  16  using direct, reflected and diffused solar radiation.  FIG. 7  shows the building  38  with window  16  and the sun S in the same position as in  FIGS. 5 and 6 , casting radiation R through the window  16 . The first panel  12  of light shelf  10  is positioned at the same height H 4  relative to the floor, as in  FIG. 6 . Second panel  36  has been deployed from the hollow of the first panel  12 , resulting in a larger shaded area D 3  and a smaller bright area B 3  than in  FIG. 6 . The width X 2  of the reflected light RR is also larger, as is the impact area W 3  of reflected light. The position and state of deployment of light shelf  10  can be controlled manually, or driven by an electric motor controlled by an interface, such as a toggle switch. As a further alternative, an electrically driven system can be automated, i.e., controlled by a microcontroller, e.g., to automatically change the state/position of the light shelf  10  depending upon the changing position of the sun and/or depending upon empirically measured parameters, such as, the brightness of illumination and/or temperature within the structure  38 . 
         [0055]      FIGS. 9 and 10  show a bracket  122  having a pivot mount  126  that supports a panel  112 . The bracket  122  has a slot  140  that is shaped to mate with track  118 , such that the bracket  122  can be slid up and down on the track  118  to position the panel  112  at a selected height. The bracket  122  has a threaded aperture  142  that receives a threaded pin  144 . The threaded pin  144  can be screwed into the aperture  142  to bear against the track  118  to secure the bracket  122  at a given position relative to the track  118 . 
         [0056]      FIGS. 11 and 12  show a similar arrangement as that shown in  FIGS. 9 and 10 , wherein a bracket  222  having a pivot mount  226  supports a panel  212 . The bracket  222  has a slot  240  that is shaped to mate with track  218 , such that the bracket  222  can be slid up and down on the track  218  to position the panel  212  at a selected height. The bracket  222  has a threaded aperture  242  that receives a threaded pin  244 . The threaded pin  244  can be screwed into the aperture  242  to bear against the track  118  to secure the bracket  222  at a given position relative to the track  218 . The track  218  is provided with a plurality of apertures  246  that may receive a portion of the threaded pin  244  to provide a mechanical overlap, preventing the bracket  222  from sliding on the track  218 . 
         [0057]      FIGS. 13 and 14  show a bracket  322  having a pivot mount  326  that supports a panel  312 . The bracket  322  has a slot  340  that is shaped to mate with track  318 , such that the bracket  322  can be slid up and down on the track  318  to position the panel  312  at a selected height. The bracket  322  has an aperture  342  that receives a slide pin  344 . The slide pin  344  can be pushed into the aperture  342  and into a selected, aligned aperture  346  to secure the bracket  322  at a given position relative to the track  318 . 
         [0058]      FIGS. 15 and 16  show a bracket  422  having a pivot mount  426  that supports a panel  412 . The bracket  422  has a slot  440  that is shaped to mate with track  418 , such that the bracket  422  can be slid up and down on the track  418  to position the panel  412  at a selected height. An electric motor  448  fastened to the bracket  422  has a pinion gear  450  that engages a rack  452  extending from the track  418 . Activation of the motor  448  causes the pinion gear  450  to engage the rack  452  raising or lowering the bracket  422  on the track  418 . A self-coiling electrical cord  454  may be used to supply electricity to the motor  448 . 
         [0059]      FIGS. 17 and 18  show a bracket  522  having a pivot mount  526  that supports a panel  512 . The bracket  522  has a threaded aperture  556  that threadedly receives a helix rod  558  which is selectively turned by a motor/reduction gear unit  560 . The helix rod  556  can be turned clockwise or counterclockwise causing the bracket  522  to move up and down, as desired. The proximity of the bracket  522  to the track  518  prevents the bracket  522  from rotating with the helix rod  556 . 
         [0060]      FIGS. 19-21  show a light shelf  610  having a bracket  622  with a pivot mount  626  that supports a hollow first panel  612  and a second panel  636  which telescopes into and out of the first panel  612 . A motor  662  with a pinion gear  664  is mounted to the underside of the first panel  612 , which has a slot  666  through which a rack  668  attached to the second panel  636  projects. The motor  662  and pinion gear  664  may have a housing  662   h  (shown in dotted lines). The motor-driven pinion gear  664  engages the rack  668  to allow the second panel  636  to be deployed, as shown in  FIG. 20  and retracted, as shown in  FIG. 21 . As described above, the state of deployment of the second panel  636  may be used to control the amount of shade provided by the light shelf  610 . A light and/or temperature sensor  670  may be employed to monitor the sunlight impacting the first panel  612  and/or the temperature. The bracket  622  may be moved up and down a track  618  and held at a selected position, e.g., by one of the apparatus described above in relation to  FIGS. 9-18 . 
         [0061]      FIGS. 22-23  show a light shelf  710  having a first panel  712  and a second panel  736 . A pair of brackets  722  with pivot mounts  726  (only one side shown) support a corresponding pair of spaced frame members  772   a,    772   b  on which are mounted a plurality of rotatable pulleys  774 . As described above, e.g., in relation to  FIGS. 1-21 , the brackets  722  may be mounted to tracks (not shown), like tracks  18 ,  20 ,  118 , etc., that allow positioning the brackets  722  at a selected position on the tracks  18 ,  20 ,  118 , etc. The first panel  712  and the second panel  736  are attached to a pair of belts  776   a,    776   b,  which are installed on the pulleys  774 . As shown in  FIG. 23 , the panels  712 ,  736  may be moved relative to one another to provide greater or lesser shading by the light shelf  710 ′ (greater)  710 ″ (lesser). More particularly, when the panels  712 ,  736  are brought more closely into alignment, lesser shading is experienced and vice versa. The position of the belts  776   a,    776   b  and panels  712 ,  736  may be controlled by a motor acting directly on a pulley  774  or on a belt, e.g.,  776   a,  e.g., via a friction wheel. 
         [0062]      FIGS. 24 and 25  show a light shelf  810  having a first panel  812  and a second panel  836 . A pair of brackets  822  with pivot mounts  826  (only one side shown) support a corresponding pair of spaced frame members  872   a,    872   b,  each having a pair of slots  878  for slideably accommodating the first panel  812  and the second panel  836 . The brackets  822  may be mounted to tracks  818 , like tracks  18 ,  20 ,  118 , etc. described above, that allow positioning the brackets  822  at a selected position on the tracks  818 . The first panel  812  and the second panel  836  are supported in the slots  878 , one above the other, allowing each to be independently slid forward and backward. As shown in  FIG. 25 , the panels  812 ,  836  may be moved relative to one another to provide greater or lesser shading by the light shelf  810 ′ (greater)  810 ″ (lesser). More particularly, when the panels  812 ,  836  are brought more closely into alignment, lesser shading is experienced and vice versa. The position of the panels  812 ,  836  may be controlled by a motor or manually. While two panels  812 ,  836  are shown, a greater number of panels  812 ,  836  may be used and accommodated in corresponding slots  878 . 
         [0063]      FIG. 26  shows a control system for motorized embodiments of the light shelves described above that may be automated to respond to ambient conditions, e.g., light intensity/brightness of illumination and temperature. A light/heat sensor  980  can sense brightness/temperature and convey that information to microcontroller  982 . The microcontroller can be programmed to analyze the input data and produce responsive output to a motor  984  that moves the light shelf  910  thereby changing the surface area exposed to incoming light and the shade provided by the light shelf  910 . 
         [0064]    It will be understood that the embodiments described herein are merely exemplary and that a person skilled in the art may make many variations and modifications without departing from the spirit and scope of the claimed subject matter. For example, while only one light shelf is shown in association with one window, a selected plurality of light shelves may be employed to control the light entering one or a plurality of windows. If a plurality of light shelves are employed they may be independently controlled or partially or completely coordinated, either electronically or by a mechanical linkage. All such variations and modifications are intended to be included within the scope of the appended claims.

Summary:
A light shelf for controlling solar radiation that impinges on a building has a panel with a pair of support brackets. The brackets run along tracks secured to the building and engage the tracks to assume a variety of elevations. The brackets can be moved independently, allowing the panel to be tilted and may have pivot joints to facilitate tilting. The panel may be mounted to the brackets in a way that allows the panel to translate horizontally. The panel may have a plurality of elements that can be adjusted to change the surface area and may be automated to respond to ambient conditions.