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CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims the benefit of U.S. Provisional Application Ser. No. 60/920,690 entitled VISION PANEL FOR MOVABLE PARTITION, MOVABLE PARTITIONS AND RELATED METHODS filed on Mar. 29, 2007, the disclosure of which is incorporated by reference herein in its entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates to generally movable partitions and, more particularly, to movable partitions, such as fire barriers, having vision panels installed therein, and to related components and methods. 
     BACKGROUND 
     Moveable partitions are utilized in numerous situations and environments for a variety of purposes. Such partitions may include for example, foldable or collapsible doors configured to close-off an opening in order to enclose a room or to subdivide a single large room into one or more smaller rooms. 
     Moveable partitions may also be used to act as security barriers, fire barriers, or as both. In such a case, the moveable partition may be configured to automatically close upon the occurrence of a predetermined event such as the actuation of an associated alarm. For example, one or more moveable partitions may be configured as a fire door or barrier wherein each door is formed with a plurality of panels connected to each other by way of hinge mechanisms. The hinged connection of the panels enables the door to fold up in a compact unit on one side of the opening or it may be stored in a pocket formed within a wall, which is designed to conceal the door and preserve the aesthetics of the room where the door is installed. When deployment of the door is necessary, the door is driven by a motor along a track, which track may be incorporated into a header above the door, until the leading edge of the door engages a mating structure. 
     When such a door or partition is used, for example, as a fire barrier, it often becomes difficult for someone on one side of the barrier to know or to determine what is taking place on the other side of the barrier. For example, it may be difficult to determine whether the room or area on an opposing side of the barrier is filled with smoke, if flames have reached the room, or if individuals are trapped on the other side of the barrier. While it is possible to open the barrier a limited distance to try and inspect what is happening on the other side, such an action may have dire consequences by enabling a fire to penetrate the opening previously closed off by the barrier. 
     Some attempts have been made at providing windows or vision panels in such partitions. However, such attempts have sometimes been difficult to implement from a manufacturing standpoint as well as from a standpoint of providing appropriate functionality, of both the partition and the window, while also maintaining desired aesthetics. 
     In accordance with certain embodiments of the present invention, a moveable partition is provided having an apparatus, structure, mechanism or other means that enable inspection of an area on one side of the partition from an opposing side of the partition while the partition is in a deployed or closed state. Additionally, some embodiments include partitions configured as a fire barrier wherein the inspection structure or device is configured to withstand the high temperatures associated with a fire without compromising the integrity of the fire barrier. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides various embodiments of movable partitions or doors that may be used, for example, as fire barriers or security barriers and that include the ability to inspect an area on an opposing side of the partition while the partition is in an extended or deployed state. 
     In accordance with one embodiment of the present invention, a barrier such as a folding door is provided. The folding door includes a first movable partition having a first plurality of panels and at least a first hinge structure having a vision panel. The at least a first hinge structure is disposed between two adjacent panels of the first plurality of panels. A second movable partition includes a second plurality of panels and at least a second hinge structure having a vision panel. The at least a second hinge structure is disposed between two adjacent panels of the second plurality of panels. Additionally, the at least a second hinge structure is laterally spaced from and longitudinally aligned with the hinge structure of the first partition. At least one bracket assembly is disposed between the hinge structure of the first partition and the hinge structure of the second partition. The at least one bracket assembly, the at least a first hinge structure and the at least a second hinge structure are cooperatively coupled with one another to substantially restrain longitudinal movement of the at least a first hinge structure relative to the at least a second hinge structure while permitting lateral movement of the at least a first hinge structure relative to the at least a second hinge structure. 
     In accordance with another embodiment of the present invention, a method of providing inspection from a first side of a barrier, such as a fire door, to a second side of the barrier is provided. The method includes disposing a first movable partition adjacent, and laterally spaced from, a second movable partition. A first vision panel is disposed in the first partition and a second vision panel is disposed in the second partition in substantial alignment with the first vision panel. The position of the first vision panel is substantially constrained with respect to the position of the second vision panel along a longitudinal direction. The first vision panel and the second vision panel are enabled to exhibit a desired amount of lateral displacement relative to each other. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The foregoing and other advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which: 
         FIG. 1  is a perspective view of a system and movable partition in accordance with an embodiment of the present invention; 
         FIG. 2  is a plan view of the partition shown in  FIG. 1 ; 
         FIG. 3  a perspective view of a movable partition shown in  FIGS. 1 and 2  with various components and sections stripped away to show certain details in accordance with an embodiment of the present invention; 
         FIG. 4  is an end view of an overhead track used in certain embodiments of the present invention; 
         FIG. 5  is a perspective view of a portion of a movable partition shown in  FIGS. 1 through 3 ; 
         FIG. 6  is an exploded view of the portion shown in  FIG. 5 ; 
         FIG. 7  is an exploded view of a vision panel in accordance with an embodiment of the present invention; and 
         FIG. 8  is a perspective view of two laterally spaced corresponding hinge panels in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1 through 3 , a system  100  is shown that includes a movable partition, for example, in the form of an accordion-type door  102 . The door  102  may be used, for example, as a security door, a fire door, for subdividing a larger space into smaller rooms or areas, as a sound barrier or as a combination of such purposes. The door  102  may be formed with a plurality of panels  104  with adjacent panels  104  being connected to one another with hinges  106  or other hinge-like members. The hinged connection of the individual panels  104  enables the panels  104  to fold relative to each other in an accordion or a plicated manner such that the door  102  may be compactly stored in a pocket  108  formed in a wall  110 A of a building when in a retracted or folded state. 
     When it is desired to deploy the door  102  to an extended position, for example, to secure an area such as an elevator lobby  112  or other area during a fire, the door  102  is displaced along a track  114  across the space to provide an appropriate barrier. When in a deployed or an extended state, a leading edge of the door  102 , shown as a male lead post  116 , complementarily or matingly engages with a jamb or door post  118  that may be formed in a wall  110 B of a building. 
     As can perhaps be best seen in  FIG. 2 , an accordion-type door  102  may include a first accordion-style partition  102 A and a second accordion-style partition  102 B that is laterally spaced from the first partition  102 A. Such a configuration may be utilized, for example, as a fire door wherein the first partition  102 A acts as a primary fire and smoke barrier, the space  122  between the two partitions  102 A and  102 B acts as an insulator or a buffer zone, and the second partition  102 B acts as a secondary fire and smoke barrier. In another application, the first partition  102 A may act as a primary sound barrier, the space  122  between the two partitions  102 A and  102 B may again act as an insulator or a buffer zone, and the second partition  102 B may act as a secondary sound barrier. 
     A drive, which may include, for example, a motor  124  and a transmission member such as a drive belt or chain  125  ( FIG. 2 ), may be configured to open and close the door  102  upon actuation thereof A trolley  128  is coupled to a portion of the chain  125  and configured to ride or slide along the track  114 . The trolley  128  may be coupled to, for example, the lead post  116  such that displacement of the trolley  128  results in corresponding displacement of the lead post  116  and the partitions  102 A and  102 B attached thereto. 
     The door  102  also includes one or more vision panels  170  that may be used to view activities occurring on one side of the door  102  from the other side of the door  102  while the door  102  is in a deployed or extended state. For example, in one embodiment, aligned vision panels  170  may be disposed in each of the space partitions  102 A and  102 B to enable one to view activities on an opposing side of the door  102 . Embodiments of such vision panels  170  will be described in further detail hereinbelow. 
     Referring briefly now to  FIG. 4 , an end view of a track  114  that may be used in accordance with an embodiment of the present invention is shown. A first channel  130  of the track  114  may be configured for receipt of individual slide mechanisms or rollers  132  ( FIG. 3 ) that may be attached to individual panels  104  associated with a first partition (e.g., partition  102 A) while a second channel  134  may be configured for receipt of similar slide mechanisms or rollers  132  associated with a second partition (e.g., partition  102 B). A central channel  136  may be disposed between the two partition channels  130  and  134  and may be configured for receipt of the trolley  128  as well as provide a raceway for the belt or chain  125 . 
     It is noted that, while the presently described embodiment is more specifically described in terms of a single accordion-type door  102 , other movable partitions may be utilized. For example, a two-door, or bi-part door, system may be utilized wherein two similarly configured doors extend across a space and join together to form an appropriate barrier. Additionally, multi-part doors may be utilized where multiple doors meet at a common door post or other structure. Also, the present invention is applicable to movable partitions or barriers other than the accordion-type doors that are specifically shown and described herein. 
     Referring now to  FIGS. 5 and 6 , a portion of a door  102  is shown in accordance with a particular embodiment of the present invention.  FIG. 5  depicts an assembled portion of the door  102 , while  FIG. 6  depicts an exploded view of the same portion of the door  102 . As has been discussed above, the door  102  may include a first partition  102 A and a second, laterally spaced partition  102 B. The partitions  102 A and  102 B each include a plurality of panels  104  coupled together with hinges  106 . The panels  104  are each coupled with respective portions of a track  114  by way of sliding mechanisms or rollers  132  such that they may be displaced along a pathway generally defined by the track  114 . 
     In accordance with one embodiment of the present invention, a separate or additional panel, referred to herein as a hinge panel  160  for purposes of convenience and clarity, is coupled between two adjacent panels  104  of a partition  102 A and  102 B and acts as a hinge between two adjacent panels while also providing longitudinal spacing (i.e., in the direction along the path defined by the track  114 ) between such panels  104 . In other words, the hinge panel  160  may be a structure that is formed to be generally similar to the hinges  106  while exhibiting a greater width than such hinges  106  such that adjacent panels  104  coupled with the hinge panel  160  are spaced from each other a greater longitudinal distance as compared to adjacent panels  104  that are coupled with the hinges  106 . 
     In one embodiment, the hinge panels  160  may also be coupled to a portion of the track  114  by way of associated sliding mechanisms or rollers (e.g., similar to slide mechanisms or rollers  132  associated with the panels  104 ). However, in another embodiment, to enable the hinge panel  160  to be laterally displaced (i.e., substantially transverse to the direction along the path defined by the track  114 ) when the door  102  is being deployed or retracted, a spacer  164  may be coupled to sliding mechanisms or rollers  166  and configured to engage or otherwise interact with a portion of the track  114  at a location generally above the hinge panel  160  and longitudinally between the adjacent door panels  104  coupled with the hinge panel  160 . In some embodiments, the spacer  164  may be configured to engage the adjacent panels  104  and act as an abutment when they rotate to a certain position relative to the hinge panel  160  to help prevent the adjacent panels  104  that are coupled with the hinge panel  160  from over-rotating during stacking thereof (e.g., when being folded and stored in the pocket  108  as shown in  FIG. 2 ). In one embodiment, the sliding mechanisms or rollers  166  may be configured to contact and roll along a surface of the track  114 , while still enabling lateral displacement of the hinge panel  160  during opening and closing of the door  102 . 
     In another embodiment, structures may be coupled to the lower portion of adjacent panels  104  that may act as spacers or bumpers  168 . The spacers or bumpers  168  also help to prevent over-rotation of the associated panels  104  during stacking of the panels  104  and placing the door  102  in a stored or stowed state. In other words, when the door  102  is being retracted and stacked or folded, the bumpers  168  of adjacent panels  104  may contact each other to prevent further rotational displacement of their associated panels  104 . Multiple spacers or bumpers  168  may be used in association with a given hinge panel  160 . For example, two or more sets or pairs of spacers or bumpers  168  may be spaced along the height of adjacent panels  104  depending, for example, on the height of the door  102 . In some embodiments, the spacers or bumpers  168  may be used in addition to the spacer  164  coupled to the upper end of the hinge panel  160 . 
     Still referring to  FIGS. 5 and 6 , a vision panel  170  is associated with each hinge panel  160 . The vision panel  170  formed in the first partition  102 A and the vision panel  170  formed in the second partition  102 B are substantially aligned such that a person standing on one side of the door  102  (when it is in a deployed or extended state) can look through the vision panel  170  in one partition (e.g.,  102 A), through the aligned vision panel  170  in the other, laterally spaced partition (e.g.,  102 B), and be able to visually inspect the area on the opposing side of the door  102 . 
     Referring briefly to  FIG. 7 , an exploded view of a vision panel  170  is shown according to an embodiment of the present invention. The vision panel  170  may include a first frame member  172  or similar structure positioned on a first side of the hinge panel  160 , a glass plate  174  (which may be fire rated) or similar structure disposed on a second side of the hinge panel  160 , and a second frame member  176  disposed on the second side of the hinge panel  160  such that the glass plate  174  and hinge panel  160  are sandwiched between the two frame members  172  and  176 . Fasteners, such as nuts  178  and bolts  180 , screws, rivets, or other fastening means, may be used to couple the frame members  172  and  176  and hinge panel  160  with one another. A sealant  182 , such as, for example, silicone caulking, may be disposed between each of the frame members  172  and  176  and the glass plate  174  to seal the vision panel  170  and reduce or eliminate fluid flow (e.g., air, smoke) through the partitions  102 A and  102 B at the locations of the vision panels  170 . Additionally, the sealant  182  may help to reduce vibrations from being transferred through the vision panel  170 . 
     In one embodiment, the vision panel  170 , when assembled, may be configured to withstand exposure to a fire for a specified period of time such that the door  102  may act as a fire barrier without being compromised by the existence of the vision panel  170 . For example, in one particular embodiment, a door  102  having a vision panel  170  that includes fire rated glazing for the glass plate  174  may be rated as a three (3) hour door under appropriate fire rating standards. 
     Referring briefly to  FIG. 8 , further details are shown with regard to hinge panels  160  that may be used in accordance with an embodiment of the present invention. One or more brackets  184  may be coupled to each hinge panel  160  to help maintain alignment of the hinge panels  160  (and, thus, maintain alignment of the associate vision panels  170 ) of a given pair of hinge panels  160 . 
     For example, a first bracket  184  may be coupled to a hinge panel  160  on an interior side thereof (i.e., at a location such that a portion of the bracket  184  extends into the space  122  between the two partitions  102 A and  102 B as shown in  FIG. 2 ). In one particular embodiment, the bracket  184  may be positioned at a location approximately 6 to 8 inches above a bottom edge  185  of the hinge panel  160 . In one embodiment, another bracket  184  may be coupled to the hinge panel  160  on an interior side thereof and at a location adjacent (e.g., just below or just above) the vision panel  170 . The brackets  184  may be configured, for example, as angles or L-shaped brackets, and coupled to the hinge panel  160  by way of screws, rivets, or other appropriate fasteners  186 . 
     The brackets  184  of two corresponding hinge panels  160  (i.e., the aligned hinge panels  160  of the first partition  102 A and the second partition  102 B) may be coupled to one another so that the two corresponding hinge panels  160  are substantially maintained in longitudinal alignment through repeated deployment and retraction of the door  102 . For example, in one embodiment, a laterally extending portion  188  of each bracket  184  may be fastened to the laterally extending portion  188  of a corresponding bracket  184 . In one embodiment, slots  190  may be formed in the laterally extending portions  188  of each bracket  184 , with slots  190  of corresponding brackets  184  being aligned and a fastener  192  being disposed in each pair of aligned slots  190  to slidably couple corresponding brackets  184  with one another. Such a configuration enables the brackets, and thus the hinge panels  160 , to be laterally displaced relative to one another within a desired range or distance, while substantially constraining relative longitudinal displacement of corresponding hinge panels  160 . In other words, such a configuration enables the hinge panels  160  to be displaced laterally towards and away from each other, while maintaining a desired line of sight through the corresponding vision panels  170 . 
     It is noted that, while a single hinge panel  160  (with associated vision panel  170 ) is shown in each partition  102 A and  102 B, such is for convenience of description and one of ordinary skill in the art would recognize that multiple pairs of aligned hinge panels  160  may be disposed at longitudinally spaced locations in the door  102  such that the door  102  includes multiple points through which one can see from a first side of the door  102  to the opposing side of the door  102 . 
     While the invention may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.

Summary:
Apparatuses and methods are provided for visual inspection across a barrier such as a fire door. In one embodiment of the present invention, a first movable partition is disposed adjacent, and laterally spaced from, a second movable partition. A first vision panel is disposed in the first partition and a second vision panel is disposed in the second partition in substantial alignment with the first vision panel. The position of the first vision panel is substantially constrained with respect to the position of the second vision panel along a first longitudinal direction. The first vision panel and the second vision panel are enabled to exhibit a desired amount of lateral displacement relative to each other.