Patent Publication Number: US-8528621-B2

Title: Solar window shade

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to devices for shading windows from sunlight, and more particularly, to an improved shading device which blocks direct sunlight while increasing passage of indirect light. 
     2. Description of the Related Art 
     Window blinds have long been available for reducing the harsh glare, and thermal heat, associated with the penetrating rays of the sun. For example, U.S. Pat. No. 169,502 to Widemann in the year 1875 discloses a venetian shade including a series of parallel slats for blocking direct rays of the sun. U.S. Pat. No. 2,749,581 issued to McCormick in 1956 discloses a form of vertical blinds wherein the louvers are disposed vertically. 
     Awning structures have also been used on the outside of buildings adjacent windows for controlling the passage of sunlight through the window. U.S. Pat. No. 2,242,697 issued to Duca in 1940 describes an awning, including a series of horizontal metal slats, that can either be lowered against the window to serve as a storm blind or raised at an angle to the window to function as a conventional awning. The awning panel includes louvers that rotate about horizontal axes for selecting how much light to admit through the window. The awning frame also pivots about a horizontal axis from just above the top of the window, and an adjustable extension rod allows a user to set the angle of the awning relative to the window. U.S. Pat. No. 2,339,878 to Reid, et al., also discloses an awning structure in which the frame can swing relative to the window, and wherein the horizontal slats can be moved between opened and closed positions. U.S. Pat. No. 6,421,966 issued to Braunstein, et al. discloses a louvered sunshade for shading window exteriors. 
     U.S. Pat. No. 2,301,568 to Moss discloses the use of sliding slatted shutter panels on be rolled in front of the window, or, alternatively, to the side of the window. 
     U.S. Pat. No. 2,654,425 to Hayner discloses a metal awning that, in one embodiment (see FIGS. 5, 6 and 10) has louvers that can be drawn to opposing sides of the awning frame or extended across the awning frame. Hayner&#39;s awning frame maintains a fixed angular relationship with the window adjacent thereto. In U.S. Pat. No. 2,791,009 to Wagner, a louver type awning is disclosed wherein the louvers themselves can be rotated about their horizontal axes, but wherein the awning frame itself is fixed relative to the window. 
     Some shade device developers have attempted to provide louvered shading devices which are responsive to the position and/or intensity of the sun. For example, U.S. Pat. Nos. 2,917,795 and 3,177,367, both issued to Brown, disclose light passage louvers for a window along with a control apparatus for controlling the rotation of such louvers in response to the position of the sun. U.S. Pat. No. 3,917,942 to McCay likewise discloses a sun tracking control system for regulating the position of shading vanes. Likewise, U.S. Pat. No. 4,505,255 to Baer discloses a solar actuated louver system wherein a control apparatus responsive to movement of the sun controls the rotation of parallel louvers that either block or admit direct sunlight, depending upon the season. 
     Awning structures that include more than one bank of louvers are also known. For example, U.S. Pat. No. 5,873,202 to Parks discloses an embodiment of an awning-type structure that includes three sets of louvers; a center louver set is fixed in position, while the surrounding outer and inner louver sets are slidably movable under manual control to vary the amount of light passed. 
     Solar collection systems are also known using two or more sets of louvers. In U.S. Pat. No. 4,279,240 to Artusy, a solar collector window device is disclosed for controlling passage of solar radiation and which includes a series of outer reflective planar vanes plus a series of inner insulating planar panels. The inner insulating panels are provided to prevent heat loss from inside a building when the sun is not present. The outer reflective vanes may be rotated synchronously with each other, and the inner insulating panels may be rotated synchronously with each other. A control mechanism is also disclosed for controlling the angle of inclination of the outer vanes and inner vanes. In U.S. Pat. No. 4,220,137 to Tesch, et al., a solar energy collection system is disclosed wherein two sets of louvers are mounted in a window structure. The first set of outer louvers is mounted vertically and serve to reflect radiation from the sun toward the inside of the room; these outer louver are rotated about their vertical axes to follow movements of the sun. The second set of inner louvers are mounted horizontally and reflect radiation from the sun onto a solar collector; these inner louvers may also be rotated about their horizontal axes to follow movements of the sun. 
     While those skilled in the art have proposed a number of different shade devices for blocking the passage of excess sunlight through a window, the majority of such prior attempts are inefficient and/or objectionable. For example, while some known shade devices may be effective in blocking the passage of sunlight through a window into the interior space of a home or commercial building, they also interfere with an occupant&#39;s view through the window. Other known shade devices may likewise be effective at blocking passage of direct rays of sunlight into a building, but also block indirect light that could be used to help illuminate the interior space, and thereby reduce amounts spent for lighting the interior space. Still other known shade devices may be effective at shading direct sunlight during certain hours of the day, or during certain seasons of the year, but lose their effectiveness during the remaining hours of the day, or during the remaining seasons of the year. Other known shade devices require extensive modification of existing windows within a building, or are otherwise complex and expensive. 
     Accordingly, it is an object of the present invention to provide a shade apparatus for shading a window of a building from the sun which effectively shades direct rays of the sun from passing into a window while minimizing interference of an occupant&#39;s view of the exterior through such window. 
     Another object of the present invention is to provide such a shade apparatus which maximizes passage of indirect ambient light through the window, to help illuminate the interior space, while simultaneously blocking out direct rays of the sun. 
     Still another object of the present invention is to provide such a shade apparatus capable of effectively shading direct sunlight from entering through the building window during substantially all hours of the day, and during substantially all seasons of the year, while nonetheless maximizing the passage of indirect light through such window. 
     Yet another object of the present invention is to provide such a shade apparatus which is relatively simple and inexpensive, and which does not require modification of windows already existing in a building. 
     A further object of the present invention is to provide such a shade apparatus which may be assembled in modular form to synchronously shade a significant number of windows in a relatively large commercial building. 
     A still further object of the present invention is to provide such a shade apparatus which may simultaneously generate clean electrical power by maintaining associated photovoltaic panels oriented directly toward the sun during substantially all daylight hours. 
     These and other objects of the present invention will become more apparent to those skilled in the art as the description of the present invention proceeds. 
     SUMMARY OF THE INVENTION 
     Briefly described, and in accordance with one preferred embodiment thereof, the present invention relates to an apparatus for shading windows of a building from the sun, and including an awning frame pivotally connected at one of its ends to the exterior of the building; the awning frame pivots about a substantially horizontal axis above the top of the window. A frame drive system is supported by the building and is coupled to the awning frame to selectively cause the opposing second end of the awning frame to pivot upwardly or downwardly in accordance with the position of the sun. A number of rotatable louvers are supported at the second end of the awning frame; a louver drive system is supported, at least in part, by the awning frame for selectively rotating the louvers in accordance with the position of the sun. In this embodiment, the pivotal movement of the awning frame, and the rotation of the louvers, tracks daily and seasonal movements of the sun to block direct rays of sunlight, while maximizing passage of indirect light rays for lighting the interior of the building. 
     Preferably, each louver has a longitudinal panel axis, and the longitudinal panel axes of the louvers are arranged to be substantially parallel to each other. In addition, each of such louvers is supported for rotation relative to the awning frame about a pivot axis, and the pivot axes of the louvers are arranged substantially parallel to each other, and substantially parallel to the longitudinal panel axes. In turn, the longitudinal panel axes of the louvers preferably extend substantially perpendicular to the pivot axis of the awning frame. 
     In the preferred embodiment, the aforementioned louvers are provided as two groups of louvers, i.e., a first group of inner louvers and a second group of outer louvers, wherein the inner louvers are generally disposed closer to the window than the outer louvers. Preferably, all of the inner louvers and outer louvers are of the same width. Ideally, the inner and outer louvers are rotatably supported at the second end of the awning frame in alternating positions, i.e., interlaced with each other, to provide a staggered configuration. Preferably, the pivot axes of all of the inner louvers substantially lie within a common plane. Likewise, the pivot axes of all of the outer louvers also preferably lie within a common plane. In the preferred embodiment, the pivot axes of the inner louvers and the outer louvers all lie substantially within the same plane as each other. The pivot axis of a particular inner louver is preferably spaced equidistant from the pivot axes of the two adjacent outer louvers that surround such inner louver. 
     The frame drive system used to raise and lower the awning frame preferably includes a threaded rod threadedly engaged by the second end of the awing frame. The frame drive system rotates the threaded rod in a first direction to pivot the second end of the awning frame upward; the threaded rod is rotated in the opposite direction to pivot the second end of the awning frame downward. The upper end of the threaded rod may be coupled to an output port of a right-angle gearbox; the input port of such right-angle gear box may, in turn, be coupled to a driveshaft rotatably supported upon the exterior of the building. Rotation of the driveshaft is translated by the gearbox into rotation of the threaded rod for raising or lowering the awning frame. Preferably, the aforementioned driveshaft is disposed above the window and extends generally parallel to the substantially horizontal pivot axis of the first awning frame. 
     The above-described frame drive system can be applied advantageously to drive two or more awning frames in conjunction with two or more windows of the building; these windows may be disposed side-by-side, or alternatively, may be located one above the other. For example, a second such awning frame may be pivotally supported in similar fashion proximate a second window on the same side of the building as are the first window and first awning frame. The above-described driveshaft can simply be extended to a second gearbox for rotating a second threaded rod, thereby raising and lowering the second awning frame in synchronization with the raising and lowering of the first awning frame. Thus, rotation of the driveshaft simultaneously pivots the first and second awning frames upwardly or downwardly. 
     The aforementioned louver drive system may also include a rotatable drive shaft mechanically coupled with the louvers in the awning frame to rotate the louvers about their pivot axes. In the preferred embodiment, the drive shaft used to control the louvers has a longitudinal axis that extends coaxially with the substantially horizontal pivot axis of the awing frame. Where a building includes a series of windows extending along one side thereof, this louver drive shaft can pass from one awning frame to the next for simultaneously rotating the louvers in each of the awning frames, particularly where such windows are arranged in side-by-side fashion. 
     If desired, the louvers may simply consist of opaque panels for blocking direct rays of the sun. In one preferred embodiment, the outer surface of one or more outer louvers includes a photovoltaic panel that generally faces away from the window, and toward the sun. In this manner, the louvers not only block direct rays of the sun from entering into the building, but also generate electrical power. 
     Alternatively, selected surfaces of the louvers may be made reflective. Those surfaces that generally face the window can then reflect indirect light back toward the window. Also, by making the outer surfaces of the inner louvers reflective, rays of light intercepted by such inner louvers can effectively be bounced off of the inner surfaces of the outer louvers back toward the window, particularly if the inner surfaces of the outer louvers are also reflective. 
     In alternate embodiments of the present invention, the frame which supports the louvers for rotation may be either fixed or pivotable. As before, the frame is coupled to the exterior of the building proximate to the window. In these alternate embodiments, the louvers are divided into outer louvers and inner louvers; the inner louvers are again disposed closer to the window than the outer louvers. A louver drive system is again supported, at least in part, by the frame, and coupled to the outer louvers and inner louvers for selectively rotating such louvers in accordance with the position of the sun. The outer louvers and inner louvers are preferably supported by the frame in alternating, interlaced positions to provide a staggered configuration of louvers. In cases where the frame does not pivot up or down, but remains in a fixed position relative to the window, the outer louvers and inner louvers are supported by the frame for rotation about substantially parallel axes; these parallel axes need not be oriented vertically. In addition, in the case of a fixed frame installation, the frame and its associated louvers may be extended vertically to cover two or more windows positioned on two or more floors of a multiple story building. 
     As described earlier, each outer louver includes an elongated panel having a longitudinal panel axis; likewise, each of the inner louvers includes an elongated panel having a longitudinal panel axis. In one preferred embodiment, each of the outer louvers is supported by an offset arm for rotational movement relative to the frame about a pivot axis; similarly, each of the inner louvers is supported by an offset arm for rotational movement relative to the frame about a pivot axis. The pivot axis of each outer louver is offset from its longitudinal panel axis by a first offset arm distance D 1 , and the pivot axis of each inner louver is offset from its longitudinal panel axis in the opposite direction by a second offset arm distance D 2 . If desired, the pivot axes of the outer louvers and the pivot axes of the inner louvers may all lie in a common plane. 
     The pivot axis of each inner louver is located substantially between the pivot axes of adjacent preceding and succeeding outer louvers; the pivot axis of each inner louver is separated from the pivot axes of the adjacent preceding and succeeding outer louvers by separation distance S. It follows that the separation distance between the pivot axes of two successive outer louvers is twice the value of S, and that the separation distance between the pivot axes of two successive inner louvers is also twice the value of S. 
     To maximize blockage of incoming direct rays of the sun while maximizing passage of indirect light into the window, the sum of the first offset arm distance D 1  and the second offset arm distance D 2  is preferably greater than the aforementioned separation distance S. Ideally, the sum of D 1  and D 2  only slightly exceeds distance S to minimize interference between adjacent louvers when the sun is incident from a sharp angle relative to the window. To simplify construction, D 1  and D 2  are preferably equal to each other. However, it is also possible to reduce one of such offsets effectively to zero, e.g., by making the pivot axes of the outer louvers coincident with the longitudinal panel axes of such outer louvers (hence, D 1  equals zero), and increasing the offset arm distance D 2  for the inner louvers to be slightly in excess of separation distance S. Alternatively, it is possible to make the pivot axes of the inner louvers coincident with the longitudinal panel axes of such inner louvers (hence, D 2  equals zero), and to increase the offset arm distance D 1  for the outer louvers to be slightly in excess of separation distance S. 
     As before, the width of the outer louvers and the width of the inner louvers is preferably kept constant at value W to maximize the view. To insure blockage of direct rays of the sun, width W is preferably greater than the separation distance S which separates the pivot axis of each inner louver from the pivot axes of each of the adjacent preceding and succeeding outer louvers. It is preferred that width W only slightly exceed separation distance S to minimize interference between adjacent louvers when the sun is at a sharp angle relative to the window. 
     Alternatively, different widths W 1  and W 2  may be used for the outer louvers and inner louvers, respectively. In that case, the sum of the widths W 1  and W 2  is preferably greater than twice the separation distance S which separates the pivot axis of each inner louver from each of the pivot axes of the adjacent preceding and succeeding outer louvers. Again, it is preferred that the sum of the widths W 1  and W 2  only slightly exceed twice the value of separation distance S to avoid interference between adjacent louvers. 
     In one preferred embodiment of the invention, the louver drive system rotates the inner louvers and outer louvers synchronously, and by the same amount. In other words, if the louver drive system is operated to rotate the outer louvers in a clockwise direction by 10 degrees, then the inner louvers are also rotated in a clockwise direction by 10 degrees. If desired, however, the louver drive system may include asynchronous gearing, causing the inner louvers to rotate asynchronously relative to the outer louvers. For example, the louver drive system may rotate the outer louvers in a clockwise direction by 10 degrees, but only rotate the inner louvers in a clockwise direction by 5 degrees. 
     As was true of the earlier-described embodiments, a photovoltaic panel may be provided upon the outer surface of one or more of the outer louvers, generally facing away from the window of the building, to generate electrical power. As was also described earlier, the outer and inner louvers may have selective surfaces that maximize the diffuse light within the visible spectrum which is reflected into the window while reducing the maximum temperature attained by the louvers and minimizing the amount of light within the infrared spectrum that radiates toward the window. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a two-story building, having two bands of windows encircling the building, wherein the windows are shaded by solar shade devices in accordance with a preferred embodiment of the present invention. 
         FIG. 2  is a view of the interior space of the building in  FIG. 1 , looking toward a shaded window. 
         FIG. 3  is a perspective view of the same window shown in  FIG. 2  but viewed from the exterior of the building. 
         FIG. 4  is a top view of the shade device shown in  FIG. 3 . 
         FIG. 5  is a side view of the shade device lowered to face the sun when the sun is relatively low on the horizon. 
         FIG. 6  is a side view of the shade device, similar to  FIG. 5 , but raised to face the sun when the sun is higher in the sky. 
         FIG. 7  is a top schematic view showing the position of outer louvers and inner louvers when the rays of the sun are essentially perpendicular to the plane of the window being shaded, e.g., a westerly-facing window in the late afternoon. 
         FIG. 8  is a top schematic view, similar to  FIG. 7 , and showing the position of the outer louvers and inner louvers when the rays of the sun are incident at approximately a 45-degree angle relative to the plane of the window being shaded, e.g., a southerly-facing window at mid-morning in the Northern Hemisphere. 
         FIG. 9  is a perspective view of the shade device, including the frame drive system and the louver drive system. 
         FIG. 10  is a sectional view, taken through lines  10 - 10  in  FIG. 9 , showing the engagement of a louver gear with a threaded louver drive rod for rotating the offset arm used to support the upper end of a louver. 
         FIG. 11  is a detailed perspective view of a right angle gear box included in the frame drive system. 
         FIG. 12  is a detailed perspective view of the pivot axis of the awning frame coaxially aligned with a louver drive shaft. 
         FIG. 13  is a sectional view taken through lines  13 - 13  in  FIG. 12 , and showing a lower toothed gear secured to the louver drive shaft for rotating the lower end of a louver drive belt. 
         FIG. 14  is a sectional view of the remote end of the awning frame, and showing the louver drive belt of  FIG. 13  engaged with an upper toothed gear secured to the threaded louver drive rod of  FIG. 10 . 
         FIG. 15  is a sectional view taken through lines  15 - 15  in  FIG. 9  and showing the threaded louver drive rod extending through the remote end of the awning frame for engaging the louver gears that rotate the offset arms used to support the upper ends of the louvers. 
         FIG. 16  is a perspective view of the idler offset arms which pivotally support the louvers at their lower ends. 
         FIG. 17  is a detailed perspective view of a solar panel secured to the outer surface of one of the outer louvers. 
         FIG. 18  is a sectional view similar to  FIG. 15  but showing an alternate embodiment wherein the inner louvers are rotated by asynchronous gears relative to the outer louvers. 
         FIG. 19  is a perspective view of a building equipped with two fixed-frame shade devices incorporating two alternate embodiments of the present invention. 
         FIG. 20  is an enlarged perspective view of the area enclosed by dashed circle  20  in  FIG. 19 . 
         FIG. 21  is a schematic top view of louvers which rotate synchronously to intercept incident sunlight at approximately 9:00 am relative to a southerly-facing window. 
         FIG. 22  is a schematic top view, similar to  FIG. 21 , but showing louvers which rotate asynchronously to intercept incident sunlight under the same conditions specified for  FIG. 21 . 
         FIG. 23  is a schematic top view of louvers used to block incident rays of sunlight angled perpendicular to the plane of the window in an alternate embodiment, wherein the outer louvers are supported for pivotal rotation about one side edge of such louvers without any offset, while the inner louvers are supported for pivotal rotation by an elongated offset arm secured to one side edge of such inner louvers. 
         FIG. 24  is a schematic top view of the louvers shown in  FIG. 23  rotated to block incident rays of sunlight approaching at an angle of approximately 45 degrees to the plane of the window. 
         FIG. 25  is a schematic top view of a variation of the embodiment shown in  FIGS. 23 and 24 , again blocking incident rays of sunlight angled perpendicular to the plane of the window, but wherein the outer louvers are supported for pivotal rotation about their central longitudinal axes without any offset, while the inner louvers are supported for pivotal rotation by an elongated offset arm secured to the central longitudinal axes of such inner louvers. 
         FIG. 26  is a schematic top view of the louvers shown in  FIG. 25  rotated to block incident rays of sunlight approaching at an angle of approximately 45 degrees to the plane of the window. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In  FIG. 1 , a multiple-story building  102  includes a southerly-facing wall  60  and a westerly-facing wall  61 . Building  102  includes, of course, northern and eastern walls, not shown in  FIG. 1 . Wall  60  includes upper and lower banks of windows  62  and  63 , respectively. Likewise, wall  61  includes upper and lower banks of windows  64  and  65 , respectively. The sun&#39;s rays  66  are shown low in the eastern morning sky. 
     Installed upon the exterior of wall  60  are a series of solar window shades, constructed in accordance with the present invention. The upper bank of windows  62  is shaded by solar window shades  67 ,  68 , and  69 , while the lower bank of windows  63  is shaded by solar window shades  70 ,  71 , and  72 . All of the solar window shades  67 - 72  are shown pivoted downwardly to approximately the same height as their associated windows to block direct rays of incident light from the early morning sun. 
     Similarly, solar window shades  73  and  74  are installed proximate upper window  64  of wall  61 , and solar window shades  75  and  76  are installed proximate lower window  65  of wall  61 . All of the solar window shades  73 - 76  are shown pivoted upwardly above their associated windows since it is too early in the day for direct rays of sunlight to strike westerly-facing windows  64  and  65 . 
       FIG. 2  illustrates occupant  77  looking outwardly through window  62  from inside building  102 . In this view, shade device  68  has pivoted further upwardly, as the sun has risen to a mid-morning position. Occupant  77  has a clear view of the outdoors through the lower two-thirds of window  62 . Louvered shade device blocks a portion of the upper third of window  62 , but occupant  77  still has a view through gaps formed between such louvers. 
       FIG. 3  is a view looking toward occupant  77 , through window  62 , from the exterior of building  102 . Shade device  68  includes a generally rectangular awning frame  101  which supports a series of rotatable louvers. If desired, rectangular frame  101  may have a length which extends the full length of the window to be shaded. However, if building  102  includes long, continuous banks of windows, then it is more practical to install two or more of such shade devices side-by side. Rectangular frame  101  includes a top upper horizontal rail  106  and a bottom horizontal rail  126 . The height of rectangular frame  101 , i.e., the distance between top rail  106  and bottom rail  126 , slightly exceeds the length of the louvers supported therein, and approximates the height of the window to be protected from the direct rays of the sun. 
     Rectangular Frame  101  is supported at each of its ends by a generally triangular frame  104 . As shown in  FIGS. 5 and 6 , triangular frame  104  includes an upper connecting leg  127  and a lower connecting leg  128 . Upper connecting leg  127  has one of its ends attached to the top of rectangular frame  101  along one side thereof, and lower connecting leg  128  has one of its ends attached to the bottom of rectangular frame  101  along the same side thereof. The opposite ends of connecting legs  127  and  128  are connected to each other at pivot axis  78  for being pivotally supported from exterior wall  60  slightly above window  62 . This collective awning frame pivots about a substantially horizontal axis proximate to the top of window  62 ; awning frame pivot axis  78  lies parallel to the window being shaded. Connecting legs  127  and  128  extend substantially perpendicular to awning frame pivot axis  78 . 
     In addition, connecting leg  127  preferably extends generally perpendicular to the plane defined by rectangular frame  101 , although this angle may be adjusted to account for variations in the distance between the top of window  62  and pivot axis  78 . The triangular frames  104  support rectangular frame  101  so that top rail  106  and bottom rail  126  of rectangular frame  101  both extend substantially parallel to awning frame pivot axis  78 . Preferably, rectangular frame  101  and each of the triangular frames  104  are formed of metal tubing; such metal tubing may be closed rectangular tubing or open C-channel stock. These preferred shapes may be modified, if desired, either for aesthetic reasons or to deter pigeons from roosting thereon. 
       FIG. 5  shows shade device  68  pivoted downwardly wherein the lower end of rectangular frame  101  is almost level with the bottom of window  62 . This position would be desired, for example, for a window facing east, during early morning hours, when the sun is low in the sky. Incoming light rays  79  and  80  are blocked by the upper portions and lower portions, respectively, of the louvers, as are all incident light rays lying between rays  79  and  80 . Accordingly, window  62  is completely shaded from direct rays of sunlight. 
     In  FIG. 6 , shade device  68  is shown pivoted upwardly wherein the lower end of rectangular frame  101  is actually above the top of window  62 . This position would correspond to a southerly-facing window in the later morning hours, when the sun is at a higher elevation in the sky. Once again, incoming light rays  79  and  80  are blocked by the upper portions and lower portions, respectively, of the louvers, as are all incident light rays lying between rays  79  and  80 . Therefore, window  62  is again shaded from direct rays of the sun, as is a portion of wall  60  lying below window  62 . 
     Within the preceding description, reference has been made to louvers rotatably supported within rectangular frame  101  of shade device  68 . Turning to  FIGS. 7-9  and  15 - 16 , such louvers include those louvers designated by reference numerals  108 ,  109 , and  110 , as well as those louvers designated by reference numerals  111  and  103 . Each of louvers  108 ,  109 ,  110 ,  111  and  103  has a central longitudinal axis about which it extends; the longitudinal axes of such louvers preferably extend parallel to each other. In addition, each of louvers  108 ,  109 ,  110 ,  111  and  103  is supported for rotation between top rail  106  and bottom rail  126  of rectangular frame  101  about its own pivot axis. 
     In the preferred embodiment illustrated in  FIGS. 1-17 , louvers  108 ,  109 ,  110 ,  111  and  103  are divided into two groups, i.e., outer louvers and inner louvers. The outer louvers include louvers  108 ,  109  and  110 . The inner louvers include louvers  111  and  103 , which are located closer to the window being shaded than the outer louvers  108 ,  109 , and  110 , as shown for example in  FIG. 7 . As is also illustrated in  FIG. 7 , inner louvers  111  and  103  are interlaced with outer louvers  108 ,  109 , and  110  in alternating positions with each other to provide a staggered configuration of louvers. Typically, each inner louver lies proximate to two outer louvers. For example, intermediate inner louver  111  lies proximate to successive outer louvers  108  and  109 . 
     Each of inner louvers  111  and  103  rotates about its own pivot axis; each such pivot axis extends substantially parallel to the central longitudinal axis of each such louver panel. In  FIGS. 7 and 8 , the pivot axis of inner louver  111  is designated as  211 , and the pivot axis of inner louver  103  is designated as  203 . Pivot axes  211  and  203  extend substantially parallel to each other and lie substantially within a common plane. Likewise, each of outer louvers  108 ,  109 , and  110  rotates about its own pivot axis  208 ,  209 , and  210 , respectively. Pivot axes  208 ,  209 , and  210  of outer louvers  108 ,  109 , and  110  are substantially parallel to each other, and also lie substantially within a common plane. Further, in the preferred embodiment, the pivot axes  211  and  203  of the inner louvers, and the pivot axes  208 ,  209 , and  210  of the outer louvers all lie substantially within the same plane. 
     As mentioned above, inner louvers  111  and  103  are interlaced with outer louvers  108 ,  109 , and  110 . Pivot axis  211  of inner louver  111  is preferably spaced equidistantly from pivot axes  208  and  209  of surrounding outer louvers  108  and  109 . In other words, pivot axis  208  lies in a first plane that is substantially perpendicular to awning frame pivot axis  78 ; pivot axis  209  lies in a second plane that is substantially perpendicular to awning frame pivot axis  78 ; and pivot axis  211  lies in a third plane also substantially perpendicular to awning frame pivot axis  78 . This third plane containing pivot axis  211  lies substantially midway between the first and second planes containing pivot axes  208  and  209 . 
     Referring briefly to  FIG. 15 , the width of outer louver is designated as W 1 ; likewise, the width of inner louver  111  is shown as W 2 . In the embodiment illustrated in  FIG. 15 , W 1  and W 2  are equal to each other, although they may differ in other embodiments. As further shown best in  FIG. 15 , the central longitudinal axis of outer louver  108  is offset from its pivot axis  208  by an offset arm  308 , which supports outer louver  108  for rotational movement relative to rectangular frame  101  about pivot axis  208 . Offset arm  308  displaces outer louver  108  from its pivot axis  208  by offset distance D 1 . Similarly, the central longitudinal axis of inner louver  111  is offset from its pivot axis  211  by offset arm  311 , which supports inner louver  111  for rotational movement relative to rectangular frame  101  about pivot axis  211 ; offset arm  311  displaces inner louver  111  from its pivot axis  211  by offset distance D 2 . In the embodiment illustrated in  FIG. 15 , D 1  and D 2  are equal to each other, although they may differ in other embodiments. While  FIGS. 7 and 15  shows offset arms  303 ,  309 ,  308  and  311  as being directly coupled to the central longitudinal axes of louvers  103 ,  109 ,  108 , and  111 , respectively, those skilled in the art will appreciate that these offset arms could be secured to their respective louvers at other points, including one of the side edges of each such louver. For example, in  FIGS. 23 and 24 , offset arms  286  and  287  are secured to side edges of louvers  284  and  285  respectively. As used herein, the “offset distance” between the pivot axis and the central longitudinal axis of the louver generally designates the distance from the pivot axis to the plane containing such louver, whether the offset arm is actually attached to the central longitudinal axis of the louver or not. 
     Within  FIG. 7 , incident rays of direct sunlight are represented by dashed arrows directed toward window  62  approximately perpendicular thereto. All of such incident rays are intercepted by louvers  108 ,  109 ,  110 ,  111  and  103 . Referring briefly to  FIG. 2 , assuming that the awning frame is fully-lowered to the level of window  62 , and further assuming that the sun is approaching from the angle shown in  FIG. 7 , then such louvers would also block the direct view of occupant  77  of the outdoors along a line of sight perpendicular to window  62 . Nonetheless, because the outer and inner louvers are staggered, and because such louvers are offset from their respective pivot axes, there are still large gaps of space between such louvers that permit viewing of the outdoors to the left, and to the right, of occupant  77 . These same large gaps between the louvers also permit a significant amount of indirect sunlight to enter through window  62  without adding unwanted heat or glare. 
     Similarly, within  FIG. 8 , incident rays of direct sunlight are represented by dashed arrows, which are now directed at approximately a 45 degree angle to window  62 . Once again, all of such incident rays of sunlight are intercepted by louvers  108 ,  109 ,  110 ,  111  and  103  before reaching window  62 . Again assuming that the awning frame is fully-lowered to the level of window  62 , and further assuming that the sun is approaching from the angle shown in  FIG. 8 , then such louvers permit occupant  77  (see  FIG. 2 ) a partial view of the outdoors along a line of sight perpendicular to window  62 ; this partial view is greater in magnitude than that provided by typical vertical blinds under similar circumstances since adjacent outer louvers and inner louvers (e.g., outer louver  109  and inner louver  111 ) approach each other more closely. Once again, relatively large gaps of space between the louvers (e.g., the gap between outer louver  108  and inner louver  111 ) permit significant views of the outdoors straight ahead, and to the right, of occupant  77 . These same large gaps between the louvers also permit a significant amount of indirect sunlight to enter through window  62  without adding unwanted heat or glare. 
     Still referring to  FIG. 15 , pivot axis  211  of inner louver  111  is separated from the pivot axes  208  and  209  of the adjacent preceding and succeeding outer louvers  108  and  109 , respectively, by a separation distance S. It is advantageous to maintain a relationship between separation distance S and offset distances D 1  and D 2  to allow for nesting of the louvers as they are rotated. As shown in  FIG. 8 , inner louver  111  approaches outer louver  109  as the louvers are rotated to intercept sun rays approaching from an acute angle relative to the window being shaded. Continued rotation may actually bring such louvers and/or their associated offset arms into contact with each other. In order to permit such louvers to nest with each other, and minimize interference with each other, the sum of the first offset arm distance D 1  and second offset arm distance D 2  is preferably made slightly greater than the separation distance S. 
     Again referring to  FIG. 15 , it is advantageous to maintain a relationship between separation distance S and the widths W 1  and W 2  of the outer louvers and inner louvers, respectively, to ensure sufficient blockage of direct rays of the sun, while allowing for nesting of the louvers, and avoiding interference, as the louvers are rotated to intercept sun rays approaching from an acute angle relative to the window being shaded. Accordingly, in the case where all of the inner louvers and outer louvers have the same width W, then W is preferably kept slightly greater than separation distance S. Preferably, successive pivot axes  208  and  209  of successive outer louvers  108  and  109  are separated from each other by a distance that is slightly less than twice the louver width W; similarly, successive pivot axes  211  and  203  of successive inner louvers  111  and  103  are separated from each other by a distance that is slightly less than twice louver width W. Alternatively, if the width W 1  of the outer louvers, and the width W 2  of the inner louvers, differ from each other, then the sum of the widths W 1  and W 2  is preferably set to be slightly greater than twice the separation distance S. 
     Rectangular frame  101  and triangular frames  104  may collectively be regarded as an awning frame, one end of which is pivotally connected to the exterior of building  102  above window  62 . Louvers  108 ,  109 ,  110 ,  111  and  103  are each rotatably supported proximate the opposite end of the awning frame. 
     In order to support the louvers along pivot axes offset from their respective longitudinal axes, a pair of offset arm rods are provided at the top and bottom of each such louver. Turning to  FIG. 10 , louver rod  212  is rotatably supported within top rail  106  of rectangular frame  101  by bushings  213  and  214  along pivot axis  208 . One end of louver rod  212  has an end cap  215  secured thereto. The other end of louver rod  212  exits top rail  106  and undergoes a ninety-degree bend to form offset arm  308 . Offset arm  308  also undergoes a ninety-degree bend before it attaches to the underside of outer louver  108 . Louver rod  212 , including offset arm  308 , supports the upper end of louver  108  at an offset distance D 1  from pivot axis  208 . While not shown in  FIG. 10 , similar louver rods are used to pivotally support the upper ends of outer louvers  109  and  110 . Likewise, similar louver rods are used to pivotally support the upper ends of inner louvers  111  and  103 , except that offset arms  311  and  303  (see  FIG. 15 ) are each 180 degrees out of phase with offset arm  308 . 
     Still referring to  FIG. 10 , a threaded louver drive rod  114  is used to control the angular orientation of the outer louvers and inner louvers. As shown in  FIG. 15 , threaded louver drive rod  114  extends within top rail  106  of rectangular frame  1 . Louver drive gear  113  includes a pair of opposing locking collars  218  and  219  for securing louver drive gear  113  onto louver rod  212  via fasteners  220  and  221 , respectively. The peripheral portion of louver drive gear  113  meshes with threaded louver drive rod  114  to form a worm gear drive. As shown in  FIG. 10 , a pair of tubular spacing collars  207  and  217  extend about louver rod  212  on opposing sides of louver drive gear  113  to maintain louver drive gear  113  in proper lateral alignment with threaded louver drive rod  114 . As threaded louver drive rod  114  rotates in either direction, louver driver gear  113  rotates accordingly, and outer louver  108  pivots as a result. As shown in  FIG. 15 , similar louver drive gears  222 ,  223  and  224  are also meshed with threaded louver drive rod  114  for pivoting louvers  111 ,  109 , and  103 , respectively. 
     The lower ends of each such louver are preferably supported by idler offset arms in a manner similar to that of the upper ends of such louvers, except that the idler offset arms used to pivotally support the lower ends of the louvers are not powered, but merely space such lower ends at the desired offset distance from the pivot axis of such louver. Referring to  FIG. 16 , lower rail  126  of rectangular frame  101  is shown as being made of C-channel stock. A pair of aligned holes  225  and  226  are formed in parallel walls  227  and  228 , respectively, for rotatably supporting one end of idler offset arm  229 ; the end of idler offset arm  229  protruding from hole  225  may include a retaining end cap, if desired. After exiting hole  226 , idler offset arm  229  undergoes a ninety-degree bend, and extends for offset distance D 2  (see  FIG. 15 ) before undergoing another ninety-degree bend. The terminal portion of idler offset arm  229  is attached to the lower end of inner louver  111 ; pocket  230  may be formed upon the upper side of louver  111  for such purpose. A similar idler offset arm  231  has one end rotatably supported by aligned holes  232  and  233 . The opposite end of idler offset arm  231  is attached to the underside of upper louver  109 , as by pocket  234 . Idler offset arm  231  spaces outer louver  109  by offset distance D 1  from the pivot axis formed by holes  232  and  233 . However, as shown in  FIG. 16 , idler offset arm  231  extends 180 degrees out of phase with idler offset arm  229 . As noted above, offset distances D 1  and D 2  may be equal to each other. 
     As noted above, threaded louver drive rod  114  is used to control the angular orientation of the louvers. In regard to  FIGS. 14 and 15 , threaded louver drive rod  114  (“the worm”) is secured at one of its ends to a toothed pulley  115  over which a toothed belt  116  is engaged. Toothed pulley  115  is housed within the upper end of connecting arm  127  of triangular frame  104 . Toothed belt  116  extends through connecting arm  127  back toward building  102 . As shown in  FIG. 12 , the lower ends of connecting arms  127  and  128  are joined to each other at the lower end, or “building end”, of triangular frame  104 . In order to support shade device  68  for pivotal movement from exterior wall  60  of building  102 , at least two angle brackets, like that shown as  132  in  FIGS. 9 and 12 , are secured to wall  60  on each side of shade device  68 . Bushings  235  and  236  are provided in aligned holes formed in the opposing parallel walls of bracket  132  for rotatably supporting a louver drive shaft  117 . In turn, the lower end of triangular frame  104  has a pair of bushings, including bushing  237 , provided within mating holes formed therein for receiving louver drive shaft  117 . Accordingly, the lower ends of triangular frames  104 , and hence, shade device  68 , are pivotally supported to building  102  via bushings  235 ,  236 , and  237 ; louver drive shaft  117 ; and bracket  132 . In this regard, louver drive shaft  117  is coincident with the horizontal pivot axis  78  of shade device  68 . 
     Within the sectional view of the lower end of triangular frame  104  shown in  FIG. 13 , a toothed pulley  125  is secured over louver drive shaft  117  within the lower end of connecting arm  127 . Toothed belt  116 , described earlier in conjunction with  FIG. 14 , is engaged over toothed pulley  125  on louver drive shaft  117 . Referring to  FIG. 9 , louver drive shaft  117  is coupled, through a right-angle gear box  238  to a master vertical louver drive shaft  239  and to reversible electric motor  118 . It will be noted that, if desired, a master vertical louver drive shaft extension  240  may extend upwardly from gear box  238  for driving another gear box  241 , and that another louver drive shaft  242  may extend from gear box  241  for controlling rotation of louvers within shade devices installed to shade windows for a floor above. 
     Summarizing the louver drive system, reversible motor  118  rotates louver drive shaft  117 , which rotates lower toothed pulley  125 , toothed belt  116 , and upper toothed pulley  115 . This, in turn, rotates threaded louver drive rod  114 , resulting in synchronized rotation of louver drive gears  113 ,  222 ,  223 , and  224 ; offset arms  308 ,  311 ,  309 , and  303  (see  FIG. 15 ) thereby pivot in unison, causing louvers  108 ,  111 ,  109 , and  103  to synchronously pivot. As louver drive shaft  117  rotates, it causes outer louvers  108 ,  109 , and  110  to translate in one direction (e.g., toward the east) while causing inner louvers  111  and  103  to translate in the opposite direction (e.g., toward the west), although all of such louvers rotate in the same relative rotational direction. Using the aforementioned synchronous gearing method, the angle of all such louvers is changed in a manner that maintains the orientation of the surfaces of the louvers parallel with one another at all times. Advantageously, louver drive shaft  117  extends through, and forms part of the substantially horizontal pivot axis of the awing frame just above the windows being shaded. As noted above, louver drive  117  shaft can easily be extended to pass through the pivot axes of multiple shade devices arranged in side-by-side fashion, whereby rotation of louver drive shaft  117  simultaneously rotates the louvers supported by each of the multiple shade devices. 
     Referring again to  FIG. 12 , louver drive shaft  117  may include one or more coupling connectors  243  along its length for joining together two successive louver drive shafts. In this manner, louver drive shaft  117  may run for the full length of exterior wall  60 , or at least that portion of exterior wall  60  that includes windows to be shaded. Thus, in the case of building  102  shown in  FIG. 1 , for example, louver drive shaft  117  may extend the full length of shade devices  70 ,  71  and  72 , while louver drive shaft  242  may extend the full length of shade devices  67 ,  68  and  69 . In this case, all six of such shade devices have their louver orientation controlled by electric motor  118 . 
     As noted above, one preferred embodiment of the invention illustrated in  FIGS. 1-15  includes the ability to pivot each shade device upwardly or downwardly about its horizontal pivot axis  78 . For this purpose, an awning drive shaft  119  is rotatably secured to the exterior of wall  60  of building  102 . Preferably, awning drive shaft  119  is supported at a horizontal elevation that is well above louver drive shaft  117 . As shown in  FIGS. 9 and 11 , awning drive shaft  119  is rotatably supported to wall  60  by a series of brackets  244  and  244 ′, one of such brackets being provided adjacent each side of shade device  68 . Each such bracket is provided with bushings  246  and  247  inserted into aligned holes of opposing parallel walls for rotatably supporting awning drive shaft  119  therein. In addition, a right angle gear box  121  is inserted within each such bracket  244 / 244 ′. As shown in  FIG. 11 , awning drive shaft  119  is coupled, via coupler  259 , to a stub shaft that enters one side of right angle gear box  121 . Awning drive shaft  119  effectively extends continuously through right angle gear boxes  121 . A threaded screw rod  122  extends downwardly from the right angle port of right angle gear box  121  via coupler  261 ; as awning drive shaft  119  rotates, threaded screw rod  122  is also caused to rotate. Screw rod  122  extends downwardly to an internally-threaded collar  123  that is pivotally secured to the remote end of connecting arm  127  of triangular frame  104 . 
     As shown in  FIG. 9 , a reversible electric motor  120  is provided for pivoting the shade devices upwardly and downwardly. Motor  120  rotates a master vertical awning drive shaft  140 , which is in turn coupled to a right angle gearbox  249 . The right angle port of gearbox  249  drives awning drive shaft  119 . Master vertical awning drive shaft extension  250  may extend upwardly from gearbox  249  to another right angle gearbox  251  for driving a second awning drive shaft used to pivot shade devices installed over the windows of a floor of building  102  above. 
     As awning drive shaft  119  is rotated by motor  120 , it causes screw rods  122 / 122 ′ (see  FIG. 9 ) to rotate, in turn causing the awning frame (i.e., rectangular frame  101  and its attached triangular frames  104 / 104 ′) to pivot on louver drive shaft  117 . Screw rods  122 / 122 ′ serve to either pull the shade device upwardly, or allow it to pivot downwardly under the force of gravity. When pivoted fully downward, rectangular frame  101  extends directly in front of window  62 , and the louvers supported therein extend substantially vertically. When pivoted fully upward, rectangular frame  101  is entirely above the elevation of window  62 , and the louvers supported therein extend substantially horizontally. 
     An electronic control circuit (not shown) is used to control the operation of reversible electric motors  118  and  120  in order to properly angle the louvers to face incident rays of direct sunlight. Such control circuitry may, if desired, be passive, whereby the relative location of the sun is easily determined as a function of the time of day, the time of year, the geographical longitude and latitude of the building, and the direction in which such windows are facing. Accordingly, the desired angle to which the louvers should be directed can be computed using appropriate computer software, and reversible motors  118  and  120  may be controlled accordingly. Alternatively, an active control circuit may be used which actively senses and tracks the position of the sun, if desired. Numerous solar tracking control circuits are commercially available for such purpose. One example of an automated method, using a computerized algorithm, for controlling a pair of motors for maintaining a planar surface aimed at the sun is disclosed in U.S. Pat. No. 7,795,568 to Sherman. 
     Whether a passive or active control system is used, the louvers track movement of the sun to maintain a perpendicular orientation between the incident rays of direct sunlight and the outwardly-facing surfaces  408 ,  411 ,  409 , and  403  (see  FIG. 15 ) of louvers  108 ,  111 ,  109 , and  103 . Any direct rays of the sun that pass between outer louvers  108  and  109  strike outer surface  411  of inner louver  111 . There will be certain instances when no direct sun rays are striking such louvers; for example, during morning hours for a westerly-facing window, during cloudy days, or when adjacent structures or vegetation serve to shade the windows. Preferably, the electronic control circuit provides an override capability to further maximize the view, and increase entry of natural indirect light in such instances. In this regard, one option is to raise the shade devices, i.e., to pivot them upwardly, as shown in  FIG. 1  for shade devices  73 - 76 . If, for some reason, the shade devices can not be raised, a second option is to rotate the louvers in either direction until the outer louvers  108 ,  109 , and  110 , and inner louvers  111  and  103  are oriented approximately at right angles to top rail  106  of rectangular frame  101 ; in this case, each outer louver (e.g.,  108 ) is nested with an adjacent inner louver (e.g.,  111 ), and is located at a distance from the next nearest adjacent pair of nested louvers (e.g.,  109  and  103 ) by almost twice the offset distance (D 1  or D 2 ). This position maximizes the amount of natural light passing into window  62 , as well as the visibility out of window  62 . Ideally, the electronic control device also adjusts the position of the shading device for optimal stability during high wind or other potentially damaging phenomena, as well as for optimal protection of the windows or other parts of the building. 
     During winter months, and particularly on weekends or holidays, or other times when building  102  is not occupied, the electronic control device may optionally be programmed to either raise the shade devices to their elevated positions, or to rotate the louvers of the shade devices to extend parallel to the sun&#39;s rays. The resulting admission of direct sunlight through window  62  thereby helps to heat the interior of building  102 . 
     The manner in which the louvers are rotated has been described thus far as a synchronous operation, i.e., the outer louvers and the inner louvers are rotated by the same amount, and at the same rate, as each other. There can be advantages, however, in using an asynchronous method of rotating such louvers. Referring to  FIG. 18 , components that correspond to those shown in  FIG. 15  are designated by similar “primed” reference numerals. Outer louver  109 ′ is rotated by louver drive gear  223 ′ in the same manner as described before. However, inner louver  111 ′ does not have a louver drive gear directly meshed with threaded louver drive rod  114 . Instead, an intermediate gear  130  is rotatably supported upon top rail  106  upon axle  252 , adjacent to, and meshed with, louver drive gear  223 ′. Intermediate gear  130  is not meshed with threaded louver drive rod  114 . Attached to intermediate gear  130  is a square-shaped gear  134 . Another square-shaped gear  131  is rotatably secured to top rail  106  about pivot axis  211 ′, proximate to, and meshed with, square gear  134 . Square-shaped gear  131  is, in turn, secured to the offset arm  311 ′ which pivots inner louver  111 ′. 
     The advantages of using an asynchronous method of operating the outer and inner louvers is illustrated by the schematic drawings shown in  FIGS. 21 and 22 . In  FIG. 21 , outer louvers  108  and  109 , and inner louvers  111  and  103 , are shown in their usual positions when driven synchronously, as in  FIG. 15 , and when the sun is incident from approximately a 45 degree angle. All of such louvers extend perpendicular to direct rays of the sun, and parallel to each other. In this case, a person looking directly out window  62  would see a clear line-of sight gap between louver  109  and louver  111  having a width G 1 . An incident direct ray of sunlight  253  that just passes the edge of outer louver  109  is easily intercepted by inner louver  111 . In contrast, in  FIG. 22 , outer louvers  108 ′ and  109 ′ are shown in their usual positions when the sun is incident from approximately a 45 degree angle, i.e., outer louvers  108 ′ and  109 ′ are perpendicular to the incident direct rays of sunlight. However, inner louvers  111 ′ and  103 ′ have been rotated more than outer louvers  108 ′ and  109 ′ and are no longer parallel thereto. Nonetheless, window  62 ′ is fully-shaded from such direct incident rays of sunlight, as light ray  253 ′ is still intercepted by the edge of inner louver  111 ′. In this case, however, the person looking directly out window  62 ′ would see a clear line-of sight gap between louver  109 ′ and louvers  108 ′/ 111 ′ having a width G 2 , which is significantly wider than width G 1  of  FIG. 21 . This larger gap also permits a greater amount of indirect light to enter window  62 ′ and light the interior of the building. 
     Now referring to  FIG. 17 , a modified form of outer louver  254  is illustrated wherein a photovoltaic panel  255  is mounted upon the outer surface of such outer louver, i.e., the surface which is normally directed toward the sun. Within  FIG. 17 , plus (“+”) and minus (−) symbols are shown to designate the positive and negative electrical terminals of photovoltaic panel  255 . If desired, distinct electrical wires can be coupled to the positive and negative terminals of each such photovoltaic panel to connect resulting electrical power to a load or storage battery (not shown). However, it is also possible to use the various components of the shade device to route electrical power to a load or storage battery. In this regard, a first electrically conductive path for generated electrical current includes jumper wire  256  extending from the positive terminal of photovoltaic panel  255  to louver rod  212  (offset arm  308 ), and to top rail  106  of rectangular frame  101 . This path further includes upper connecting leg  127  of triangular frame  104 , threaded collar  123 , screw rod  122 , right angle gear box  121 , and awning drive shaft  119  for connection to the positive terminal of a storage battery (not shown). The conductive path for the negative terminal of photovoltaic panel  255  uses the idler offset arm  257  secured to the lower end of louver  254 , bottom rail  126  of rectangular frame  101 , lower connecting leg  128  of triangular frame  104 , louver drive shaft  117  for connection to the negative terminal of such storage battery. In this case, top rail  106  and bottom rail  126  of rectangular frame  101  must be electrically isolated from each other, and upper connecting leg  127  and lower connecting leg of triangular frame  104  must be electrically isolated from each other. 
     Referring again to  FIG. 15 , the surfaces of the outer and inner louvers may include reflective surfaces to further enhance the performance of the shading device. For example, the outer surfaces  411  and  403  of inner louvers  111  and  103 , respectively, may include a light-colored, or reflective surface, to block all of the direct rays of the sun striking at a 90 degree angle, while allowing such rays to be diffused and reflected off of the inner surfaces  508  and  509  of outer louvers  108  and  109 , respectively, for passage into window  62 . Alternatively, the outer surfaces  411  and  403  of inner louvers  111  and  103 , respectively, may include a fresnel lens with prisms designed to reflect direct rays of the sun striking such outer surfaces. Such fresnel lenses may be backed by a clear frosted material to diffuse any direct rays of the sun that pass through the fresnel lens as a result of imperfections in the prisms. 
     Still referring to  FIG. 15 , the inner surfaces  508  and  509  of outer louvers  108  and  109 , respectively, may be provided with selective surfaces that maximize the reflection of light within the visible spectrum, and either minimize, or maximize, the emission of light rays in the infrared spectrum. Such surfaces can be utilized to reduce the maximum temperatures attained by the louvers, minimize the radiant heat striking the outside surface of the window  62  and building exterior wall  60 , and maximize the light rays within the visible spectrum that are reflected toward the surface of the window  62 . Doing so helps to capture diffused light that bounces off of the outer surfaces  411  and  403  of inner louvers  111  and  103 , as well as light reflected off of exterior wall  60 , and re-direct such light through the window to help illuminate the interior of the building. If desired, the outer surfaces of the inner and/or outer louvers may be light-colored, or reflective, to reflect radiant heat energy that might otherwise build up between the shade device and the exterior of the shaded window. 
     Referring now to  FIGS. 19 and 20 , an alternate embodiment of the invention is illustrated using a fixed awning frame rather than a pivoting awning frame. Awning frame  260  is installed over window  262 , with the upper end of awning frame  260  proximate to exterior wall  264 , and lower rail  265  of awning frame spaced apart from window  262  by side supports  266  and  267 . As in the case of rectangular frame  101  of  FIG. 9 , alternating outer louvers  268 / 269  and inner louvers  270  are rotatably supported in awning frame  260  by offset louver rods for rotating in accordance with the time of day to block direct rays of sunlight, while maximizing the passage of indirect sunlight through window  262 , and minimizing the obstruction of the view therethrough. Awning frame  260  maintains louvers  268 ,  269  and  270  at a fixed angle of inclination, e.g., 45 degrees to a horizontal plane, but facilitates the rotation of such louvers to track east-to-west movement of the sun during each day. A louver motor is still required to rotate the louvers, but no frame pivot motor is required. 
     As shown in  FIG. 19 , a further alternate embodiment includes a shade frame  271  placed in a vertical orientation over another window. Vertical outer louvers  272  and  274  are interlaced with vertical inner louvers  275  and  276 , and are rotated to block incident direct rays of sunlight. In this embodiment, all of such louvers are supported by fixed frame  271  for rotation about substantially vertical axes. 
     While  FIG. 19  shows shade frame  271  covering a single window for a single floor of a building, those skilled in the art will appreciate that, in a multiple story building, fixed shade frame  271 , and louvers  272 ,  274 ,  275  and  276 , could be lengthened (i.e., extended vertically) to cover two or more windows that are vertically aligned, one above the other, on different floors of the same face of the building. Obviously, the width of shade frame  271 , and the number of provided louvers, may be increased to protect windows of greater width. 
     Thus far, the described embodiments have used bent louver rods, or offset arms, to support both the inner louvers and the outer louvers in a manner which displaces the pivot axes away from such louvers. In  FIGS. 23 and 24 , an alternate embodiment of the present invention is illustrated schematically wherein two outer louvers  280  and  281  pivot about pivot axes  282  and  283 , respectively. In this case, pivot axis  282  actually coincides with one edge of louver  280 , without any offset arm or louver rod; the offset distance has been reduced to zero. Likewise, pivot axis  283  actually coincides with one edge of louver  281 , without any offset arm or louver rod. In contrast, inner louvers  284  and  285  are secured to offset arms  286  and  287  which pivot about pivot axes  288  and  289 , respectively. If desired, the relationship illustrated can be reversed, with the inner louvers having zero offset, and wherein the outer louvers are supported by offset arms. As before, outer louvers are interlaced in alternating fashion with the inner louvers. Offset arms  286  and  287  are now longer than in the earlier embodiments, since the offset of outer louvers  280  and  281  has been reduced to zero. 
     In  FIG. 23 , incident rays of light are indicated perpendicular to the shaded window, and all of such incident rays are blocked by louvers  280 ,  281 ,  284  and  285 . In  FIG. 24 , the incident rays of light now approach from an angle of approximately 45 degrees to the plane of the shaded window, and outer louvers  280  and  281 , and inner louvers  284  and  285 , have been rotated to extend perpendicular to such incident rays of light. Once again, all of such rays are blocked, and yet a significant clear line-of-sight gap exists, perpendicular to the window, between such louvers, both to maximize the view of the outdoors and to maximize admission of indirect light through the window. 
       FIGS. 25 and 26  illustrate an alternate embodiment that is a variation of the embodiment described in regard to  FIGS. 23 and 24 . In  FIG. 25 , outer louvers  380  and  381 , and inner louvers  384  and  385 , are again used to block incident rays of sunlight angled perpendicular to the plane of the window. This time, however, outer louvers  380  and  381  are supported for pivotal rotation about their respective central longitudinal axes  382  and  383 , without any offset. Inner louvers  384  and  385  are supported for pivotal rotation by respective elongated offset arms  386  and  387 . Offset arm  386  pivots about axis  388  at one end, and is secured at its other end to the central longitudinal axis of inner louver  384 . Similarly, offset arm  387  pivots about axis  389  at one end, and is secured at its other end to the central longitudinal axis of inner louver  385 . In  FIG. 26 , outer louvers  380  and  381 , and inner louvers  384  and  385  have been rotated to block incident rays of sunlight approaching at an angle of approximately 45 degrees to the plane of the window. It will be appreciated that the above-described relationship may be reversed, i.e., inner louvers  384  and  385  could be directly rotated about their central longitudinal axes without any offset, while outer louvers  380  and  381  could be pivoted by offset arms secured to such outer louvers along their respective central longitudinal axes. 
     Those skilled in the art will now appreciate that an improved shade apparatus has been described for shading a window of a building from the sun. The described shade device effectively shades direct rays of the sun from passing into a window while minimizing interference of an occupant&#39;s view of the exterior through such window. The disclosed shade device further maximizes the passage of indirect ambient light through the window to help illuminate the interior space. The shade device is easily controlled to effectively shade direct sunlight from entering a building window during substantially all hours of the day, and during substantially all seasons of the year. Moreover, the described shade apparatus is relatively simple and inexpensive, and avoids any modification of windows already existing in a building. In addition, the disclosed shade device can be assembled in modular form to synchronously shade a large number of windows in a relatively large commercial building. Further, photovoltaic panels may be provided on the outer faces of the outer louvers to face, and track, the sun throughout the day. 
     While the present invention has been described with respect to preferred embodiments thereof, such description is for illustrative purposes only, and is not to be construed as limiting the scope of the invention. For example, while the above-described preferred embodiment identifies a particular mechanical coupling for transmitting rotational motion from  117  to arms  308 ,  311 ,  309  and  303 , other known mechanical coupling components may be used for this purpose, including right angle gears, rotating shafts, racks and pinions, tie rods, cables, pulleys, chains, belts, clutches, levers, and other devices commonly used for transmitting power. Indeed, one could provide an electrical stepping motor within the frame of each awning shade device to rotate louver drive worm shaft  114  for controlling the outer and inner louvers, and eliminate toothed belt  116  (see  FIGS. 13 and 14 ), toothed pulley  125  (see  FIG. 13 ), toothed pulley  115  (see  FIG. 14 ), and louver drive shaft  117 ; a pair of electrical wires would then be routed to each awning frame to control the electrical stepping motor housed within each such frame. Various other modifications and changes may be made to the described embodiments by those skilled in the art without departing from the true spirit and scope of the invention as defined by the appended claims.