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RELATED APPLICATIONS 
       [0001]    This patent application is a division of U.S. patent application Ser. No. 14/164,061 that was filed Jan. 24, 2014, for an invention titled CLASSROOM BALLISTIC BARRIERS, and also claims the benefit of U.S. Provisional Patent Application Ser. No. 61/756,505 that was filed on Jan. 25, 2013, for an invention titled CLASSROOM BARRIER. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates generally to ballistic barriers. More specifically, the present invention relates to a wall opening barrier for a doorway or windows in a classroom or the like. 
       BACKGROUND 
       [0003]    In today&#39;s society there has arisen a need to provide protection for students against active shooters (gunmen) attacking defenseless victims on school campuses. There are many approaches being considered for such protection including but not limited to; more campus police, arming teachers, ballistic backpacks, etc. The present invention simply attempts to make Almost any classroom a “safe room”. Creating “safe rooms” on campuses drastically reduces or eliminates the “opportunity” and permits trained professionals adequate time to respond to the threat. The barrier must be simple to operate; it must be bullet resistant and it must prevent breaching for some predetermined length of time, thus allowing time for local police/SWAT to respond. 
       SUMMARY OF THE INVENTION 
       [0004]    The classroom ballistic barriers of the present disclosure are ingress barriers comprising at least one ballistic panel specifically designed to block entry through a classroom door or window or any other door or window where warding off an armed assailant is desirable. 
         [0005]    The classroom ballistic barrier can be a sliding panel or hinged panel depending upon the configuration of the door opening or window opening to be blocked. The barrier must be locked from the inside with no chance for it to be unlocked from the exterior. It must be simple to operate, it must be bullet resistant, and lastly it must be impenetrable for some predetermined length of time. 
         [0006]    The invention of the present disclosure is comprised of at least one sliding ballistic panel. Since classroom doors must swing outward (for exiting purposes), it is advisable that the classroom ballistic barrier be located on the inside of the door opening or window opening. Having the barrier on the inside of the door opening has several advantages. They are: 
         [0007]    The door does not need to be closed prior to the barrier being shut. 
         [0008]    The barrier mechanisms, frame, track, etc. are shielded by the wall and jamb of the doorway. 
         [0009]    The barrier locking mechanism is shielded by the wall and jamb of the doorway. 
         [0010]    The exposed portion of the barrier (the exterior) is completely smooth so there is nothing to pry on to gain entry. 
         [0011]    Because the barrier is completely smooth from the exterior there will be nothing to suggest a vulnerability to the barrier from the assailant&#39;s point of view. 
         [0012]    Because the barrier is located inside the door opening (for someone looking down a long hallway) it will not be immediately obvious which rooms are the “safe rooms.” 
         [0013]    The invention of the present disclosure automatically locks when the barrier is slid into position and can only be unlocked from the inside. A bar is connected to the sliding barrier so when the panel is slid across the door opening, the locking bar falls, under the force of gravity, into locking position. 
         [0014]    In some embodiments, the locking bar may be spring-loaded to urge the locking bar to move into the locking position as the barrier is slid into position. In some embodiments, an urging plate is located across the storage side channel to ensure the locking bar begins to fall as the barrier is slid into position. 
         [0015]    In some embodiments, the locking bar is painted or made of a material that is easily visible, such as optic orange, so it is obvious from visual observation that it is or is not properly positioned to lock the barrier. A resting stop is located at the bottom of the channel or within the bottom channel for the locking bar to rest against assuring that it is visible when in the “locked” position. The locking bar must be lifted up from inside the room to open the barrier. 
         [0016]    The present invention has anticipated the need for a retention plate with and an angle flange that engages the bottom track so the barrier panel cannot be lifted from sliding engagement with the bottom track to gain entry. The barrier panel height is sized only slightly less than the dimension between the top track and bottom track so the panel cannot be lifted to gain entry or permit a gun barrel to be projected between the barrier panel and the floor. 
         [0017]    It has been considered that this could have application for almost any door opening and almost any installation where a deranged person might choose to attack defenseless individuals. 
         [0018]    The barrier panel is comprised of ballistic nonflammable fiberglass making the panels suitable for use in school corridors. The ballistic fiberglass has multiple layers of woven fiberglass making them incredibly difficult to cut through even when using carbide cutting tools. In fact, they are cut at the factory using a sophisticated water-jet. This feature makes them highly suitable for preventing breaching. 
         [0019]    The barrier panel could be installed so that in the open position it is already past the door frame to ensure no interference with the door frame when closing. 
         [0020]    A handle could be mounted on the barrier panel to facilitate closing. 
         [0021]    The classroom barrier can be disguised as a simple bulletin board for everyday use so as not to unduly alarm young students or inform would be assailants. 
         [0022]    When closed, the barrier panel is nested in a channel on at least three sides. 
         [0023]    It has been considered that many different materials could be utilized in place of the ballistic fiberglass depending upon the threat and response time of local law enforcement. Such materials are known to those of skill in the art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    Exemplary embodiments of the invention will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only exemplary embodiments and are, therefore, not to be considered limiting of the invention&#39;s scope, the exemplary embodiments of the invention will be described with additional specificity and detail through use of the accompanying drawings in which: 
           [0025]      FIGS. 1A-1C  illustrate a series of perspective views from inside a room showing an exemplary ballistic barrier panel transitioning from a stored position to a fully deployed position.  FIG. 1A  is a perspective view showing an open doorway with the barrier panel in its stored position nested between an upper channel and a lower channel, and also showing a handle on the ballistic barrier panel.  FIG. 1B  is a perspective view of an open doorway with the ballistic barrier panel slid partway over the doorway, and showing the locking bar falling towards its locking position. As shown, the locking bar is a contrasting color to assist in its observation visually.  FIG. 1C  is a perspective view of the ballistic barrier panel blocking the open doorway and nesting into the side panel so that the locking bar is in its locking position and the ballistic barrier panel is nests in channels on three sides. 
           [0026]      FIG. 2  is a perspective view of the open doorway from outside the room, showing the ballistic barrier panel completely blocking the doorway from physical or ballistic intrusion. 
           [0027]      FIGS. 3A-3C  illustrate a series of perspective sectional views looking upward from a section taken at floor level.  FIG. 3A  is a perspective sectional view showing the ballistic barrier panel nested in the upper and lower channels when the ballistic barrier panel is in its storage position, leaving the doorway open.  FIG. 3B  is perspective sectional view showing the ballistic barrier panel nested in the upper and lower channels when the ballistic barrier panel has been moved to partially block the open doorway.  FIG. 3C  is perspective sectional view showing the ballistic barrier nested three ways in the side, upper, and lower channels (note that a portion of the ballistic barrier panel remains in the lower channel) when the ballistic barrier panel is in its fully deployed position, blocking the open doorway. 
           [0028]      FIGS. 4A-4B  illustrate elevation perspective views showing the exemplary ballistic barrier panel transitioning from a stored position to a fully deployed position.  FIG. 4A  is an elevational perspective view of the ballistic barrier panel nested in the lower channel when the ballistic barrier panel is in its storage position, leaving the doorway open.  FIG. 4B  is an elevational perspective view showing the ballistic barrier panel nested in the lower channel when the ballistic barrier panel has been moved to partially block the open doorway and also showing the locking bar moving towards its locking position. 
           [0029]      FIG. 5  is a cutaway perspective view of the lower portion of the ballistic barrier panel showing the pivotal connection for the locking bar that enables the locking bar to fall, under the force of gravity, as the ballistic barrier panel is moved slidably from its storage position towards the fully deployed position. 
           [0030]      FIG. 6  is a cutaway perspective view of an alternative exemplary embodiment showing a tethered lock pin securing the ballistic barrier panel in the stored position. 
           [0031]      FIG. 7  is vertical section view of the ballistic barrier panel disposed within the bottom channel showing the retention plate with an angled flange for retaining the ballistic barrier panel within the bottom channel. 
           [0032]      FIGS. 8A-8K  illustrate a series of inside a room elevation views showing an exemplary four-panel ballistic barrier transitioning from stored positions to a fully deployed position blocking a large window opening.  FIG. 8A  is an elevation of four ballistic barrier panels wherein each ballistic barrier panel is in its storage position, leaving the window opening open.  FIG. 8B  is an elevation view showing a first ballistic barrier panel moved to partially block the window opening and a first locking bar moving towards its locking position.  FIG. 8C  is an elevation view showing the first ballistic barrier panel overlapping a second ballistic barrier panel and in position to capture the second ballistic barrier panel for tandem movement and blocking more of the window opening.  FIG. 8D  is an elevation view showing the first ballistic barrier panel overlapping and capturing the second ballistic barrier for tandem movement to further block the window opening.  FIG. 8E  is an elevation view showing the first ballistic barrier panel moving the second ballistic barrier to further block the window opening, the first locking bar trails the first ballistic barrier panel.  FIG. 8F  is an elevation view showing the first ballistic barrier panel and the second ballistic barrier panel fully extended to further block the window opening, the trailing first locking bar is disposed in its locking position.  FIG. 8G  is an elevation view showing a third ballistic barrier panel moved to partially block the window opening and a second locking bar moving towards its locking position.  FIG. 8H  is an elevation view showing the third ballistic barrier panel overlapping a fourth ballistic barrier panel and in position to capture the fourth ballistic barrier panel for tandem movement and blocking more of the window opening.  FIG. 8I  is an elevation view showing the third ballistic barrier panel overlapping and capturing the fourth ballistic barrier for tandem movement to further block the window opening.  FIG. 8J  is an elevation view showing the third ballistic barrier panel moving the fourth ballistic barrier panel to further block the window opening, the second locking bar trails the third ballistic barrier panel.  FIG. 8K  is an elevation view showing the third ballistic barrier panel and the fourth ballistic barrier panel fully extended to fully block the window opening, the trailing second locking bar is disposed in its locking position. 
           [0033]      FIG. 9  is a perspective view of the first locking bar in its locking position to inhibit opening of the overlapping first and second ballistic barrier panels. 
           [0034]      FIG. 10  is a section view along an elevated horizontal plane through the wall, window, and second ballistic barrier panel showing the first locking bar in its locking position to inhibit opening of the overlapping first and second ballistic barrier panels. 
           [0035]      FIG. 11  is a horizontal section view of portions of the first and second ballistic barrier panels showing a capture assembly to enable tandem movement of the first and second ballistic barrier panels. 
           [0036]      FIG. 12  is a horizontal section view of portions of the first and third ballistic barrier panels showing an astragal that provides ballistic protection across the seam when the first and third meet in abutting engagement. 
           [0037]      FIG. 13  is a vertical section view of a first upper channel and a second upper channel as attached to a wall and showing a first upper stop and a second upper stop that inhibit the first and second ballistic barrier panels from over-extending over the window opening. 
           [0038]      FIG. 14  is a cutaway elevation upper leading corner of the first ballistic barrier panel showing a stop clearance for engaging the first upper stop and a suspension roller. 
           [0039]      FIG. 15  is a perspective end-on view of the first and second ballistic barrier panels with the stop clearance of the second ballistic barrier panel approaching the second upper stop. 
           [0040]      FIG. 16  is a perspective end-on view of the first and second ballistic barrier panels with the stop clearance of the second ballistic barrier panel engaging the second upper stop and the stop clearance of the first ballistic barrier panel engaging the first upper stop. 
           [0041]      FIG. 17  is a horizontal section of the wall and the storage side channel showing the free end of the locking bar fully disposed substantially vertically and nested within the storage side channel. 
           [0042]      FIG. 18  is vertical cutaway elevation view of the storage side channel and the locking bar as it falls, under the force of gravity, while the free end is retained in slidable engagement within the storage side channel. 
       
    
    
     DETAILED DESCRIPTION 
       [0043]    Exemplary embodiments of the present invention will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. It will be readily understood that the components of the present invention, as generally described and illustrated in the Figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of exemplary embodiments of the apparatus, system, and methods of the present invention, as represented in  FIGS. 1A through 18 , is not intended to limit the scope of the invention, as claimed, but is merely representative of exemplary embodiments of the invention. 
         [0044]    The phrases “connected to,” “coupled to” and “in communication with” refer to any form of interaction between two or more entities, including mechanical, electrical, magnetic, electromagnetic, fluid, and thermal interaction. Two components may be coupled to each other even though they are not in direct contact with each other. The term “abutting” refers to items that are in direct physical contact with each other, although the items may not necessarily be attached together. 
         [0045]    The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated. 
         [0046]    The classroom ballistic barriers of the present disclosure are ingress barriers comprising at least one ballistic panel specifically designed to block entry through a classroom door or window or any other door or window where warding off an armed assailant is desirable. 
         [0047]    Turning to  FIGS. 1A-1C , a series of perspective views of an exemplary ballistic barrier (generally designated  10 ) as viewed from inside a room  12  with a doorway  14  in an adjacent wall  16  is provided to show a ballistic barrier panel  18  as it transitions from a stored position to a fully deployed position.  FIG. 1A  shows an open doorway  14  with the ballistic barrier panel  18  in its stored position nested between an upper channel  20  and a lower channel  22 . The ballistic barrier panel  18  has a leading edge  24  and a trailing edge  26  (shown in  FIGS. 1B and 1C ). In  FIG. 1A , the trailing edge  26  in nested within or abuts against a storage side channel  28 . Each ballistic barrier panel  18  has a threat side  30  (shown in  FIG. 2 ) and a non-threat side  32 . The threat side  30  is the side a would-be assailant may encounter, and in the depicted instance is the side facing away from the interior of the room  10 . The non-threat side  32  faces into the room  10  and may be disguised as a simple bulletin board for everyday use so not to unduly alarm young students or inform would be assailants. Although a bulletin board, cork board, or some other classroom wall covering (not shown) can be applied to the non-threat side  32 , it has been omitted from  FIG. 1A  so not to obscure the components of the ballistic barrier panel  18 . 
         [0048]    For ease in moving the ballistic barrier panel  18 , a handle  34  is provided. To provide easy sliding movement, the ballistic barrier panel  18  is suspended from the upper channel  20  by heavy-duty suspension rollers  36  (partially obscured, see also  FIG. 14 ) and the top edge and bottom edge of the ballistic barrier panel  18  nest within the upper channel  20  and the lower channel  22 , respectively. 
         [0049]    The ballistic barrier panel  18  is depicted as the same in each figure, differing only in its position with respect to the adjacent wall  16 .  FIG. 1B  shows the ballistic barrier panel  18  drawn part way across the doorway  14 , exposing the trailing edge  26  and a locking bar  38 . The locking bar  38  is pivotally connected to the lower portion of the trailing edge  26  of the ballistic barrier panel  18 . As the ballistic barrier panel  18  is slidably moved towards closing the doorway  14 , the locking bar  38  drops, under the force of gravity, from a substantially vertical storage position (depicted in  FIG. 1A ) through an angled disposition (depicted in  FIG. 1B ) towards as substantially horizontal locking position (depicted in  FIG. 1C ). 
         [0050]    In  FIG. 1C , the ballistic barrier panel  18  is shown blocking the open doorway  14  and nesting into a side panel  40  so that the locking bar  38  is in its locking position and the ballistic barrier panel  18  nests in channels on three sides, the upper channel  20 , the lower channel  22 , and the side channel  40 . Because the side channel  40  is offset from the doorway  14  opening, there is no apparent weakness on the threat side  30  when an assailant encounters the ballistic barrier  10 . Also, once fully deployed, the ballistic barrier panel  18  cannot be moved until the locking bar  38  is lifted by someone inside the room  12  to release the ballistic barrier panel  18  so that it can be retracted. 
         [0051]    As shown in  FIG. 2 , there is no indication that the doorway  14  may be blocked by the ballistic barrier  10  that is visible in the hallway. Further, if the ballistic barrier  10  is deployed while the door  42  is closed, an assailant looking down a long hallway cannot determine which classrooms are equipped with a ballistic barrier  10  system. 
         [0052]      FIGS. 3A-3C  illustrate a series of perspective sectional views of the ballistic barrier  10  looking upward from a section taken at floor level.  FIG. 3A  shows the ballistic barrier panel  18  nested in the upper and lower channels  20 ,  22  when the ballistic barrier panel  18  is in its storage position, leaving the doorway  14  open.  FIG. 3B  shows the ballistic barrier panel  18  nested in the upper and lower channels  20 ,  22  when the ballistic barrier panel  18  has been moved to partially block the open doorway  14 .  FIG. 3C  shows the ballistic barrier panel  18  nested three ways in the side, upper, and lower channels  40 ,  20 ,  22  when the ballistic barrier panel  18  is in its fully deployed position, blocking the open doorway  14 . Although the lower channel  22  does not extend across the threshold of the open doorway  14 , a portion of the ballistic barrier panel  18  proximate the trailing edge  26  remains in the lower channel  22  so that the ballistic barrier  10  cannot be retracted from outside the room  12 . 
         [0053]      FIGS. 4A-4B  are elevation perspective views showing the slidable engagement of the lower portion of the ballistic barrier panel  18  as nested in the lower channel  22 .  FIG. 4A  shows a retention plate  44  disposed proximate the bottom edge  46  of the ballistic barrier panel  18 . As shown in  FIG. 4B , the retention plate  44  has an angled flange  48  that travels beneath a curled flange  50  that runs along the length of the lower channel  22 . The angled flange  48  will engage the curled flange  50  to inhibit the ballistic barrier panel  18  from being lifted from its nested relationship with the lower channel  22 . 
         [0054]      FIG. 5  is a cutaway perspective view of the lower portion of the ballistic barrier panel  18  proximate the trailing edge  26  and showing the pivotal connection  52  of the locking bar  38  that enables to the locking bar  38  to fall, under the force of gravity, as the ballistic barrier panel  18  is moved slidably from its storage position towards the fully deployed position.  FIG. 5  also shows that the angled flange  48  of the retention plate  44  travels beneath the curled flange  50  of the lower channel  22  to inhibit the ballistic barrier panel  18  from being lifted from its nested relationship with the lower channel  22 . 
         [0055]      FIG. 6  illustrates an alternative exemplary embodiment of the ballistic barrier  10  showing a tethered lock pin  54  securing the ballistic barrier panel  18  in the stored position. The tethered lock pin  54  must be released by pulling the lock pin  56  out of its locked position either by pulling on the lock ring  58  or the tether  60 . The tethered lock pin  54  immobilizes the ballistic barrier panel  18  preventing a student from inadvertently moving the ballistic barrier panel  18  by pulling on the handle  34 . This is an added safety feature to prevent curious younger students who may not understand how to open the ballistic barrier  10  if inadvertently closed while an adult is not in the room  12  from being trapped within the room  12 . 
         [0056]      FIG. 7  is vertical section view showing yet another perspective of the ballistic barrier panel  18  disposed within the bottom channel  22  showing the retention plate  44  with the angled flange  48  for retaining the ballistic barrier panel  18  within the bottom channel  22 . 
         [0057]      FIGS. 8A-8K  illustrate a series of step-by-step movements for transitioning an exemplary four-panel ballistic barrier  10  from stored positions to a fully deployed position blocking a large window opening  62 . Of course, it should be understood that a single panel or double panel embodiment of the ballistic barrier  10  can be used to block smaller window openings  62  from undesired ballistic intrusion. Also, a person of ordinary skill in the art of ballistic shielding, armed with the disclosure of this application, would understand how to modify the embodiments disclosed herein to block other types of window openings frequently found in schools, other window openings such as a sidelight window, a transom window, and a clearstory window. 
         [0058]      FIG. 8A  is an elevation of four ballistic barrier panels  18  wherein each ballistic barrier panel is in its storage position, leaving the window opening  62  open. By way of example, the window opening  62  comprises five window panes  64  separated by four mullions  66 . The four ballistic barrier panels  18  are stacked two deep in an overlapping fashion on each side of the window opening  62 . On one side of the window opening  62 , a first ballistic barrier panel  68  is visible from inside the room  12 , while a second ballistic barrier panel  70  is obscured from view. On the other side of the window opening  62 , a third ballistic barrier panel  72  is visible from inside the room  12 , while a fourth ballistic barrier panel  74  is obscured from view. As depicted, first ballistic barrier panel  68  has an astragal  75  secured to its leading edge  24 ; however, it should be understood that alternatively the astragal  75  could be secured to the leading edge  24  of third ballistic barrier panel  72 . The astragal  75  will be described with reference to  FIG. 12  hereinafter. 
         [0059]    In the storage position, the first ballistic barrier panel  68  is nested in slidable engagement within the upper channel  20  and the lower channel  22 , while the second ballistic barrier panel  70  is nested in slidable engagement within a second upper channel  76  and a second lower channel  78 . Additionally, the ballistic barrier  10  may comprise the storage side channel  28  and a second storage side channel  80  wherein the first ballistic barrier panel  68  rests against the storage side channel  28  and the second ballistic barrier panel  70  rests against the second storage side channel  80 . Likewise, on the other side of the window opening  62 , the third ballistic barrier panel  72  is nested in slidable engagement within the upper channel  20  and the lower channel  22 . It should be understood that the lower channel  22  may extend the full length of the window opening  62  because unlike doorway thresholds, windows are not routinely used for ingress and egress from a room  12 . Additionally, the ballistic barrier  10  may comprise a third storage side channel  82  and a fourth storage side channel  84  wherein the third ballistic barrier panel  72  rests against the third storage side channel  82  and the fourth ballistic barrier panel  74  rests against the fourth storage side channel  84 . 
         [0060]      FIG. 8B  shows the first ballistic barrier panel  68  moved to partially block the window opening  62  and a first locking bar  86  moving towards its locking position. Although the sequence of steps taken to block the window opening  62  are described in a particular order to facilitate understanding the invention, it should be understood that order that steps can be taken can differ with some steps being taken simultaneously if undertaken by more than one person. Such changes in the sequence of steps are contemplated by this disclosure. 
         [0061]    The first locking bar  86  of  FIG. 8B  may be the same as has been described herein with respect to the doorway embodiment of the ballistic barrier  10 , except that the free end  88  (not shown in  FIG. 8B ) is not slidably retained within the storage side channel  28 . Otherwise, the first locking bar  86  may be painted or made of a material that is easily visible, such as optic orange, so it is obvious from visual observation that it is or is not properly positioned to lock the ballistic barrier  10 . Also, the first locking bar  86  may have a pivotal connection (not visible in  FIG. 8B , but similar to pivotal connection  52  depicted in  FIG. 5 ) disposed at the lower portion of the first ballistic barrier panel  68  proximate its trailing edge  26  that enables to the locking bar  86  to fall, under the force of gravity, as the ballistic barrier panel  18  is moved slidably from its storage position towards the fully deployed position. 
         [0062]      FIG. 8C  shows the first ballistic barrier panel  68  overlapping the second ballistic barrier panel  70  and in position to capture the second ballistic barrier panel  70  for tandem movement and blocking more of the window opening  62 .  FIG. 8D  shows the first ballistic barrier panel  68  overlapping and capturing the second ballistic barrier  70  for tandem movement to further block the window opening  62  and the first locking bar  86  resting substantially horizontal in the lower channel  22 . The capturing of the second ballistic barrier  70  for tandem movement will be described in more detail with reference to  FIG. 11  hereinafter. 
         [0063]    As shown in  FIG. 8E , the first ballistic barrier panel  68  has been moved in tandem with the second ballistic barrier panel  70  to expose adjacent wall  16  behind the second ballistic barrier panel  70  and to further block the window opening  62 , the first locking bar  86  trails the first ballistic barrier panel  68 .  FIG. 8F  shows the first ballistic barrier panel  68  and the second ballistic barrier panel  70  fully extended to further block the window opening  62 , the trailing first locking bar  86  is disposed in its locking position (as will be described with reference to  FIGS. 9 and 10  hereinafter). As shown, the ballistic barrier  10  blocks approximately half of the window opening  62 . 
         [0064]      FIGS. 8G-8K  follow a similar sequence as just described in  FIGS. 8A-8F  but are directed to the movement of the third and fourth ballistic barrier panels  72 ,  74 . As shown in  FIG. 8G , the third ballistic barrier panel  72  has been moved to partially block the window opening  62  revealing a second locking bar  88  moving towards its locking position.  FIG. 8H  shows the third ballistic barrier panel  72  overlapping the fourth ballistic barrier panel  74  and in position to capture the fourth ballistic barrier panel  74  for tandem movement and blocking more of the window opening  62 . In  FIG. 7I , the third ballistic barrier panel  72  is shown overlapping and capturing the fourth ballistic barrier panel  74  for tandem movement to further block the window opening  62 , and the second locking bar  88  has dropped, under the force of gravity, to rest substantially horizontal in the lower channel  22 . 
         [0065]      FIG. 8J  shows the third ballistic barrier panel  72  moving the fourth ballistic barrier panel  74  to further block the window opening  74  while the second locking bar  88  trails the third ballistic barrier panel  72 . In  FIG. 8K , the third ballistic barrier panel  72  and the fourth ballistic barrier panel  74  are shown fully extended to fully block the window opening  62 , the trailing second locking bar  88  is disposed in its locking position. As shown, the astragal  75  overlaps the leading edge  24  of the third ballistic barrier panel  72  to block the seam created by the abutting engagement of the leadings edges  24  of the first and third ballistic barrier panels  68 ,  72 . 
         [0066]      FIGS. 9 and 10  provide differing views of how the first locking bar  86  drops into it locking position when the first ballistic barrier panel  68  is fully extended to block the window opening  62 . As shown, an abutment stop  90  extends across bottom channel  22  and may further extend across second bottom channel  78 . The abutment stop  90  is disposed low enough in the bottom channel  22  and second bottom channel  78  so that the ballistic barrier panels  18  slid over the abutment stop  90  so to present little or no resistance to the sliding movement of the ballistic barrier panels  18 , but high enough in the bottom channel  22  to provide a secure abutment against which the free end  92  of the first locking bar  86  abut firmly. Although  FIGS. 9 and 10  show a gap between the free end  92  and the abutment stop  90 , the gap is shown merely to facilitate the understanding of the abutment stop  90 . In practice, the gap, if any, would be minimal or minute so that the ballistic barrier panels  18  cannot be wiggled by an assailant to create unwanted seams or openings in the ballistic barrier  10 . It would be preferred that the free end  92  abut against the abutment stop  90 . Of course, it should be understood that a similarly situated abutment stop  90  may be disposed within the lower channel  22  to engage the free end  92  of the second locking bar  88  and stop undesired retraction of the third ballistic barrier panel  72 . 
         [0067]      FIG. 11  shows an exemplary capture assembly  94  that enables tandem movement of the first and second ballistic barrier panels  68 ,  70 . The capture assembly  94  comprises an engaging flange  96  secured to the second ballistic barrier panel  79  and a drag flange  98  secured to first ballistic barrier panel  68 . So not to present and assailant with an opening at the overlapping interface of the first and second ballistic barriers  68 ,  70 , the engaging flange  96  and drag flange  98  extend the full vertical height of the first and second ballistic barriers  68 ,  70 , respectively. When the first ballistic barrier panel  68  is moved in the direction of Arrow A, the leading surface  100  of the drag flange  98  will engage and capture the engaging flange  96  so that the first and second ballistic barriers  68 ,  70 , move in tandem thereafter. 
         [0068]    Additionally, a ballistic material or end cap (not shown) may be secured to the leading surface  102  of the engaging flange  96  and/or the leading edge  24  of the second ballistic barrier panel  70  to present additional ballistic shielding at the overlapping interface of the first and second ballistic barriers  68 ,  70 . Further, although  FIG. 11  shows only an exemplary capture assembly  94 , those skilled in the art would understand that many other types of capture assemblies may be made to accomplish the capture and tandem movement functions described above and contemplated by this disclosure. 
         [0069]      FIG. 12  shows portions of the first and third ballistic barrier panels  68 ,  72  just before abutting engagement. To effect abutting engagement, the first ballistic barrier panel  68  is moved in the direction of Arrow A and the third ballistic barrier panel  72  is moved in the direction of Arrow B. When abutting engagement of the leading edges  24  of the first and third ballistic barrier panels  68 ,  72  is accomplished, the astragal  75  spans the abutment seam created and provides ballistic protection across the abutment seam. 
         [0070]      FIG. 13  is a vertical section view of a upper channel  20  and a second upper channel  76  as attached to the adjacent wall  16  and showing a first upper stop  104  and a second upper stop  106  that inhibit the first and second ballistic barrier panels  68 ,  70  from over-extending over the window opening  62 , and assure that the abutting engagement of the first and third ballistic barrier panels  68 ,  72  is as snug as possible. 
         [0071]      FIG. 14  is a cutaway elevation of the upper leading corner of the first ballistic barrier panel  68  showing a stop clearance  108  for engaging the first upper stop  104  and the heavy-duty suspension rollers  36 . The heavy-duty suspension rollers  36  are for suspending the ballistic barrier panels  18  for slidable movement of the ballistic barrier panels  18 . The rollers  110  for each ballistic barrier panel  18  roll over the curled flange  50  of the upper channel  20  or the curled flange  50  of the second upper channel  76 . The stop clearance  108  is at least as wide as the first upper stop  104  to assure as snug a fit as possible. Similarly, the upper leading corner of the second ballistic barrier panel  70  has a stop clearance  108  for engaging the second upper stop  106  and heavy-duty suspension rollers  36  for suspending the second ballistic barrier panel  70  for slidable movement  18 . Again, the stop clearance  108  for the second ballistic barrier panel  70  is at least as wide as the second upper stop  106  to assure as snug a fit as possible. 
         [0072]      FIG. 15  is a perspective end-on view of the first and second ballistic barrier panels with the stop clearance  108  of the second ballistic barrier panel  70  approaching engagement with the second upper stop  106 . 
         [0073]    In  FIG. 16 , a perspective end-on view of the first and second ballistic barrier panels  68 ,  70  shows the stop clearances  108  of the second ballistic barrier panel  70  engaging the second upper stop  106  and the stop clearance  108  of the first ballistic barrier panel  68  engaging the first upper stop  104 . 
         [0074]      FIGS. 17 and 18  illustrate an alternative exemplary embodiment of the sliding engagement of the free end  92  of the locking bar  38  as may be used for a doorway or single-panel window opening embodiment of the ballistic barrier  10 .  FIG. 17  shows the free end  92  of the locking bar  38  fully disposed substantially vertically and nested within the storage side channel  28 . To retain the free end  92  within the storage side channel  28  a spring-loaded detent button  112  and a retention flat  114  are provided. At initial installation, the spring-loaded detent button  112  may be depressed so that the free end  92  of the locking bar  38  may be inserted into the storage side channel  28  and tucked under the retention flat  114  as shown. The trailing edge  26  of the ballistic barrier panel  18  abuts against the retention flat  114  to obscure the locking bar  38  from view from inside the room  12 . 
         [0075]      FIG. 18  is vertical cutaway elevation view of the storage side channel  28  and the locking bar  38  as it begins to fall (because the ballistic barrier panel  18 , not shown, has been moved slightly), under the force of gravity, while the free end  92  is retained in slidable engagement within the storage side channel  28 . The phantom lines are provide to show inner surfaces of the storage side channel  28 , the locking bar  38 , and the spring-loaded detent button  112 . The spring-loaded detent button  112  slides along the inner surface of the curled edge  50  of the storage side channel  28  and thereby retains the free end  92  within the storage side channel  28  as the ballistic barrier panel  18  (not shown) is moved towards full deployment. 
         [0076]    In some embodiments, the ballistic barrier panel  18  may trigger an alarm system as it is closed to block a doorway  14  or window opening  62 . This alarm system could sound an audible alarm similar to a fire alarm but different to notify teachers and students at other locations to close their ballistic barrier panels  18 . This alarm system could also alert authorities and responders to the potential threat of an assailant. In some instances, the triggering of the alarm system may cause the remaining ballistic barriers  10  on campus to close automatically. With each of these embodiments, a person of skill in the art would know how to implement an alarm system, alert authorities, and/or automatically close ballistic barrier panels  18 . 
         [0077]    While specific embodiments and applications of the present invention have been illustrated and described, it is to be understood that the invention is not limited to the precise configuration and components disclosed herein. Various modifications, changes, and variations which will be apparent to those skilled in the art may be made in the arrangement, operation, and details of the methods and systems of the present invention disclosed herein without departing from the spirit and scope of the invention.

Summary:
A classroom barrier comprising a sliding panel or hinged panel designed to block a classroom door or window opening in certain emergency situations such as the presence of an armed assailant. The barrier is locked from the inside with no chance for it to be unlocked from the exterior. The classroom barrier is simple to operate, bullet resistant, and impenetrable for some predetermined length of time.