Patent Publication Number: US-11649661-B2

Title: Apparatus for barricading an outward swinging door to provide physical security

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a non-provisional application of U.S. Provisional Patent Application Ser. Nos. 63/046,832, filed Jul. 1, 2020 and 63/038,317, filed Jun. 12, 2020. These applications are incorporated herein by reference in their entireties, and priority to them is claimed. 
    
    
     FIELD OF THE INVENTION 
     This application relates to apparatuses for barricading a door, such as is useful in preventing forced entry into a dwelling or business. 
     INTRODUCTION 
     Various physical security measures can be used with doors at a dwelling or business that are designed to discourage forced entry into the premises.  FIG.  1    shows a door  10 , which is typically attached to a frame  12  by hinges  14 .  FIG.  1    shows various devices that have been used to provide physical door security, which are typically accessible to a user from inside the building being secured. These security measures are well known, and hence only briefly explained. In this example, the door  10  is hinged to allow it to pivot outwards of a building when the door  10  is opened, as is typical in a commercial or public building. 
     Element  20  comprises a latch which includes portions mounted (typically using screws) to both the door  10  and the frame  12  (or an adjacent wall more generally). The portion of the latch  20  affixed to the door  10  includes a slidable latch  22 , which a user can slide to meet with a loop  24  on the portion affixed to the frame  12 . Element  30  comprises a chain latch, which is generally similar to latch  20 , although in this latch  30  the portion affixed to the door includes a chain  32  with a bit at its end. A user can position the bit within a slot  34  on the portion affixed to the frame  12 . In either of latches  20  or  30 , security against forced entry is provided by the sliding latch  22  or the chain  32 . However, such security is not perfect. A force imparted outside the door such as from an assailant wishing forced entry can cause latches  20  or  30  to fail. Particularly, a sufficient force to the door  10 —such as a force pulling the door outwards—can cause the sliding latch  22  or chain  32  to break, or can cause the screws affixing the devices  20  or  30  to become dislodged from either the door  10  or the frame  12 . 
     Element  40  comprises a well-known door knob. When the knob is turned, a latch  44  is retracted into the door  10  from a recess  46  that has been morticed into the frame  12 , thus allowing the door to be opened. When not turned, or when locked such as by using a key (not shown) or thumb turn  42 , the latch  44  will remain extended in the recess  46 , thus providing physical security against forced entry via force provided by the latch  44  against the door frame  12 . Element  50  is typically called a “dead bolt.” Like knob  40 , dead bolt  50  includes a latch  54  which can be retracted from or extended into a recess  56  provided in the door frame  12 , again using a key or a thumb turn  52 . Door knobs  40  and dead bolts  50  also do not provide complete security against forced entry. In both cases, a sufficient outside force on the door  10  can cause the door knob  40  or dead bolt  50  to fail. Particularly, the recesses  46  or  56  morticed into the door frame  12  reduce the door frame material, thus weakening the material against external forces, raising the possibility that the latches  44  or  54  will break through the recesses  46  or  56 . A strike plate (not shown) can be affixed (screwed) to the frame  12  over the recesses which will add further structural integrity against external forces, but such protection is limited by the strength of the screws involved. 
     Element  60  comprises another form of a door latch. In this example, a portion  64  is affixed to, or within, the door  10 , which includes a sliding latch  66 . This latch  66  can slide into a hole  68  morticed in the floor  70 . The sliding latch  66  may be controlled by a key or thumb turn  62 . Like latches  20  and  30  however, latch  60  can be prone to failure. A sufficient force outside the door  10  can cause the portion  64  affixed to the door  10  to become dislodged, or the latch  66  to be broken. 
     SUMMARY 
     A system useable to barricade a door is disclosed. The system may comprise: an anchor comprising an upper portion and a lower portion, wherein the lower portion is configured to be insertable in an opening in a floor proximate to an inside surface of the door; and a lock affixable to the door, wherein the lock comprises a stop and a key plate, wherein the stop is configured to be proximate to an outside surface of the door and the key plate is configured to be proximate to the inside surface of the door when the lock is affixed to the door, wherein the upper portion is configured to engage the key plate when the lower portion is inserted in the opening in the floor. 
     In one example, the lower portion and the opening in the floor are cylindrical. In one example, the lock further comprises a cross member that connects the stop and the key plate to affix the lock to the door. In one example, the stop and cross member comprise an integrated piece. In one example, the cross member comprises a bolt, wherein the bolt is configured to connect to the key plate though an opening in the key plate. In one example, the bolt comprises a threaded end, and further comprising a nut, wherein the nut is configured to affix to the threaded end of the bolt to connect the bolt to the key plate. In one example, the cross member is configured to connect the stop and the key plate through an opening in the door. In one example, the cross member is configured to connect the stop and the key plate around the door. In one example, an inside surface of the key plate is configured to contact the inside surface of the door, and an inside surface of the stop is configured to contact the outside surface of the door, when the lock is affixed to the door. In one example, the lower portion is configured to be vertically inserted into the opening in the floor. In one example, the key plate comprises a channel, and wherein the lower portion is configured to be insertable through the channel to insert the lower portion in the opening in the floor, wherein the upper portion is configured to engage the channel of the key plate when the lower portion is inserted in the opening in the floor. In one example, the channel, the opening in the floor, the upper portion and the lower portion, are each cylindrical. In one example, a cross section of the upper portion and the lower portion are equally sized. In one example, the upper portion comprises a first key and the key plate comprises a second key, wherein the upper portion is configured to engage the key plate by connection of the first and second keys when the lower portion is inserted in the opening in the floor. In one example, the first key is configured to connect with the second key by vertically inserting the first key into the second key, or by vertically inserting the second key into the first key, when the lower portion is vertically inserted into the opening in the floor. In one example, the upper portion comprises a first vertical planar surface, and wherein the first key is positioned on the first vertical planar surface. In one example, the second key is formed on a second vertical planar surface of the key plate. In one example, the first and second vertical surfaces are configured to slidably contact each other when the first key connects with the second key. In one example, the upper portion comprises an overhang above the first key. In one example, the overhang is configured to contact the key plate when the lower portion is vertically inserted into the opening in the floor. In one example, a bottom of the first key is configured to contact a bottom of the second key when the lower portion is vertically inserted into the opening in the floor. In one example, the system further comprises a receptacle, wherein the receptacle is configured to be positioned in a hole in the floor proximate the inside surface of the door, wherein the receptacle comprises the opening in the floor proximate to the inside surface of the door. In one example, an underside of the lower portion is configured to contact the receptacle when the anchor is placed in the receptacle. In one example, the upper portion is configured to engage the key plate when the lower portion is inserted in the opening in the floor and when the door is closed in a door frame. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    shows various physical security measures that can be used with doors at a dwelling or business to discourage forced entry into the premises, in accordance with the prior art. 
         FIG.  2    shows a door barricading system, including an anchor, a lock, and a receptacle, in position relative to a door being barricaded. 
         FIG.  3    show an example of the anchor and receptacle. 
         FIGS.  4 A- 4 C  show how the receptacle can be installed in a floor, and how the receptacle can thereafter receive the anchor. 
         FIGS.  5 A- 5 D  show the lock and its components, and the manner in which the lock can be affixed to the door. 
         FIG.  6    shows how the anchor can be simultaneously vertically inserted into the receptacle and into the lock. 
         FIGS.  7 A- 7 B  show operation of the system to barricade a door when it is closed in a door frame. 
         FIGS.  8 A- 8 D  show a modification to the system that allows the door to be barricaded while still allowing the door to be opened by a gap. 
         FIGS.  9 A and  9 B  show modifications to the anchor. 
         FIGS.  10 A and  10 B  show a modification to the lock in which the key plate is affixed to the inside surface of the door. 
         FIGS.  11 A- 11 C  show a modification to the lock in which the lock does not require a bolt affixed through the door. 
         FIGS.  12 A- 12 C  show a modification in which the body of the anchor is positioned through the lock. 
         FIGS.  13 A and  13 B  show another modification in which the anchor can be used to barricade two (double) doors. 
         FIG.  14    shows that the stop may be formed of more than one piece, and further shows the inclusion of optional electronics in the system. 
         FIG.  15    shows that the opening in the receptacle can be covered by a cap. 
         FIG.  16    shows that the system may include a hanging device to store the anchor when not in use. 
         FIG.  17    shows various components that can be included in a kit to sell the system. 
     
    
    
     DETAILED DESCRIPTION 
     By way of summary, and referring to element numerals described later herein, various aspects of Applicant&#39;s invention involve the use of a barricading system  90  to barricade a door  10  from forced entry. System  90  is particularly useful when applied to doors that swing outwardly, as is common in commercial and public buildings. 
     The system  90  includes an anchor  500  insertable by a user into a receptacle  150  mounted into a floor  70  on the inside on the door  10 , and a lock  400  affixable to the door. The anchor  500  includes an upper portion  502  designed to connect with the lock  400 , and a lower portion  504  that preferably fits within the receptacle  150 . The lock  400  includes a stop  412  designed to contact the outside surface  10   a  of the door  10 , and a key plate  404  on the inside of the door  10 . When the anchor  500  is vertically inserted into the receptacle  150 , the upper portion  502  of the anchor  500  engages the key plate  404  affixed to the door  10 . Engagement between the anchor  500  and the key plate  404  can occur using corresponding keys on these components, or the anchor can be insertable through a vertical channel  430  on the key plate  404 . Engagement between the anchor  500  and the lock  400  prevents the door  10  from swinging outwards: when an assailant wishing forced entry attempts to swing the door  10  outwards, the stop  412 —which is ultimately mechanically connected to the floor  70  via the connected lock  400  and anchor  500 —will barricade the door from opening. The anchor  500  can be removed from the receptacle  150  when the user doesn&#39;t desire to barricade the door, such as when the user may wish to open the door  10 . 
       FIG.  2    shows a first example of a barricading system  90 , which includes the anchor  500  and lock  400  just mentioned.  FIG.  2    shows the anchor  500  in place with respect to a door  10  that is being secured. Specifically, the anchor  500  has been inserted into a receptacle  150  mounted into the floor  70  inside the door  10 , and has been connected to the lock  400  affixed to the door  10 . The connection between the anchor  500  and the lock  400  is established using keys  508  and  416  respectively positioned on these components, as explained further below. Note that a door  10  secured by the system  90  may be protected by other physical security measures as well, such as those described with respect to  FIG.  1   . 
       FIG.  3    shows the anchor  500  and receptacle  150  in isolation. The anchor  500  as mentioned above includes an upper portion  502  that includes a key  508 , and a lower portion  504  that preferably fits within an opening  156  in the receptacle  150 . In this example, both the upper and lower portions are formed from cylindrical pieces. This is preferred because cylindrical bar stock is easily accessible and cheap. That being said, the shape of these components  502  and  504  are not critical, and either of both can be made of different shapes. Preferably, the upper portion  502  includes a flat surface  506  into which the key  508  has been formed. Although not strictly necessary, an overhang  509  can be located above the key  508 . These structures  506 ,  508 , and  509  may be formed by milling the cylindrical upper portion  502 . 
     The receptacle  150  includes a sidewall  154  whose inner diameter defines the size of the opening  156 , and whose outer diameter is designed to fit in a hole  160  drilled in the floor  70 . Preferably, the receptacle  150  also includes a horizontal lip  152  that overlies the floor  70  when the receptacle  150  is installed in the hole  160 . The lip  152  may include a beveled edge  153  to smooth the transition from the top of the floor  70  to the top of the lip  152 . Although not shown, the lip  152  may also be morticed into the floor  70  so that it is flush with the top of the floor. Furthermore, the lip  152  may be absent, in which case the receptacle  150  may include only the sidewall  154  which may be made flush with the top of the floor  70 . In this regard, opening  156  in the receptacle  150  may be considered generally as an opening in the floor  70 . Indeed, receptacle  150  isn&#39;t entirely necessary in the system  90 , and instead the lower portion  504  can be inserted instead directly into an opening in the floor without the receptacle present. 
       FIGS.  4 A- 4 C  show steps involved in the installation of the receptacle  150 , and subsequent use of the anchor  500  as part of the system  90 . The lock  400  mounted to the door  10 , to which the anchor  500  also connects, isn&#39;t shown in  FIGS.  4 A- 4 C  but will be explained in subsequent figures. As shown in  FIG.  4 A , the hole  160  is drilled in the floor  70  proximate to and inside of the door  10 . The location at which the hole  160  is drilled relative to the door  10  will depend on the dimensions of the anchor  500  and the lock  400 , as explained subsequently. Typically, the floor  70  comprises a solid substrate such as a cement foundation, wood, or the like. After the hole  160  is drilled, and as shown in  FIG.  4 B , the sidewall  154  of the receptacle  150  is preferably secured within the hole  160 , such as by the use of an adhesive or cementing material  158 . Thereafter, as shown in  FIG.  4 C , the user may slide the lower portion  504  of the anchor  500  vertically downward into the receptacle&#39;s opening  156 , which acts to barricade the door  10  when the anchor also connects with the lock  400  as explained subsequently. Preferably, the height (h 1 ) of the lower portion  504  is equal to the depth of the opening  156 , such that when the anchor  500  is positioned in place, the bottom of its upper portion  502  will rest on the upper surface of the lip  152  as shown in  FIG.  4 C . This provides stability, as well as keeps the anchor  500  from damaging the floor  70 . That being said, if the receptacle  150  doesn&#39;t include a lip  152 , the upper portion  502  may rest on the top surface of the floor  70 . Because the lower portion  504  is designed to slide into opening  156  of the receptacle  150 , this lower portion  504  and opening  156  would have the same shape (e.g., cylindrical, rectangular, etc.). 
     As just mentioned, the lower portion  504  of the anchor  500  is preferably sized to slide into the opening  156 , and if both are cylindrical they also may rotate with respect to each other. That being said, these portions also preferably have a tight tolerance, such that the lower portion  504  is firmly retained (and will not “wiggle”) within the opening  156 . As explained later, the dimensions of the anchor  500  and the receptacle  150  can vary, and it should be understood that the drawings do not necessarily depict these components to scale. To provide some idea of envisioned sizing of the anchor  500  and receptacle  150 , and referring to  FIG.  3   , the lower portion  504  may have a diameter (d) in the range of 0.5-1.5 inches and a height (h 1 ) of 2.0-4.0 inches, which would also set the dimensions of the corresponding opening  156  in the receptacle  150 . The upper portion  502  may have a height (h 2 ) of 1.5-4.0 inches, and a radius r of 1.0-4.0 inches. These dimensions though are merely examples, and any dimensions for the anchor  500  can be used that enable the functionality as described herein. 
       FIGS.  5 A- 5 D  show the lock  400 , which as noted earlier is mountable to the door  10  and connects to the anchor  500  when it is inserted in the receptacle  150 . The lock  400  preferably comprises a number of pieces, including a key plate  404 , a stop  412 , and a horizontal cross member  408  such as a bolt. The bolt  408  and stop  412  may be formed as a single integrated piece as shown, and may be milled from cylindrical bar stock in one example. The key plate  404  contains the key  416  discussed earlier, and is mountable proximate to the inside surface  10   b  of the door  10 . The bolt  408  passes through an opening  13  formed in the door  10  from its outside surface  10   a , such that when the bolt  408  is connected to the key plate  404 , the stop  412  is mounted proximate to the outside surface  10   a  of the door. As  FIG.  2    suggests, opening  13  is preferably formed in the door  10  towards the bottom edge of the door, and preferably opposite the hinges  14 , which allows the system  90  to barricade the door where the door swings open. The manner and position at which opening  13  is formed may depend on the material of the door, and may be formed through the bulk of the door (e.g., a wooden door) or through a mullion (e.g., the metal frame of a glass door). A drill bit  214  ( FIG.  17   ) may be used to form the opening  13 , and preferably the diameter of the opening  13  is just slightly larger than the diameter of the bolt  408 . 
     As best shown in  FIG.  5 A , the pieces of the lock  400  are connected through the opening  13  in the door using a fastener, such as a nut  406 , which is connected to threads  410  on the end of the bolt  408 . Specifically, the bolt  408  is passed through the opening  13  and through a horizontal opening  414  of the key plate  404 . As best shown in the plan and cross-sectional views of  FIGS.  5 C and  5 D , the key plate  404  includes a recess  418  to broaden out the diameter of the opening  414  to accommodate the nut  406  when it is affixed to the threads  410  of the bolt. As such, when the nut  406  is affixed, the nut is recessed below a planar surface  419  of the key plate  404 . Having the nut  406  recessed in this fashion facilitates the connection of the anchor  500  to the key plate  404 , as explained further below.  FIG.  5 B  shows the stop  412 , bolt  408 , and key plate  404  as connected (e.g., using nut  406 ), but with the door  10  removed for easier viewing. In one example, when these components are affixed to each other, they are also firmly affixed to the door  10 . In this regard, the dimensions of the components can be sized such that when connected to the door, the stop  412  is in firm contact with the outside surface  10   a  of the door, and the key plate  404  is in firm contact with the inside surface  10   b  of the door. In other words, the distance “x” between the inside surfaces of the stop  412  and the key plate  404  can roughly equal the thickness of the door. Although not shown, surfaces of the key plate  404  and stop  412  that contacts the surfaces  10   b  and  10   a  of the door  10  can include pads comprised of a high-density rubber or plastic. Such pads can help protect the door  10  from becoming marred by the lock  400 , and may help to absorb an external force F that might be applied to the door  10 , as explained further below. 
     The anchor  500 , lock  400 , and receptacle  150  may be made of various materials, and preferably are formed of materials with good mechanical strength able to provide barricading functionality without breaking. For example, these components may be formed of aluminum, steel, or high-density plastics such as PTFE, high-density rubbers, etc. The anchor  500 , lock  400 , and receptacle  150 , or their components, may be milled, cut or molded to the correct shapes to provide the barricading functionality described. The anchor  500 —i.e., the upper and lower portions  502  and  504 —is preferably solid for best mechanical strength. However, in other examples, the upper and lower portions  502  and  504  may be hollow to some degree, which can be useful to reduce the weight of the anchor  500 . The upper portion  502  may also be designed with different shapes to reduce weight or ease manufacturing, as described later with respect to  FIGS.  9 A and  9 B . 
       FIG.  6    shows connection of the anchor  500  to the lock  400  as would occur when the anchor  500  is being used to barricade a door  10  to which the lock  400  is affixed. In  FIG.  6   , the door  10  to which the lock  400  is affixed isn&#39;t shown for simplicity. The lower portion  504  of the anchor  500  is slipped vertically into the opening  156  in the receptacle  150  by a user as described earlier. At the same time that the lower portion  504  is inserted, the key  508  of the anchor  500  is vertically inserted into the key  416  on the key plate  404 . In the example shown, the key  508  on the upper portion  502  of the anchor  500  can be viewed as a male key insertable into a female key  416  of the key plate  404 . However, these could also be reversed, with the upper portion  502  including a female key and the key plate  404  including a male key. In the example shown, the keys have angled edges, and are roughly trapezodial in shape, although other shapes (e.g., “T” shapes) could be used for the keys as well. In this manner, when key  508  slips vertically into key  416 , the lock  400  is firmly held to the anchor  500 , such that a horizontal force F cannot pull them apart. Notice that the simultaneous vertical insertion of the lower portion  504  into the receptacle  150  and the key  508  into key  416  requires proper sizing of the components as well as proper positioning of the receptacle  150  with respect to the door-mounted lock  400 . 
     The keys  416  and  508  can be connectable in other manners, and such connection does not necessarily need to simultaneously coincide with vertical insertion of the lower portion  502  into the opening  156  of the receptacle  150 . For example, the keys  416  and  508  can be connected after the lower portion  502  has been inserted into the receptacle  150 , such as by clamping, snapping, or by other mechanisms. 
     Notice that when the anchor  500  is vertically inserted into the lock  400 , the anchor  500  can “bottom out” in one or more of a number of different ways. First, the bottom of the lower portion  504  can contact the bottom of the opening  156  in the receptacle  150 . Second, the bottom of the upper portion  502  can contact the floor  70  or the lip  152  of the receptacle  150  if present. Third, the bottom of the key  508  can contact the bottom  417  ( FIG.  5 A ) of key  416 . Fourth, the overhang  509  can contact the top of the key plate  404 . Preferably, the components of the system  90  are sized and installed such that some or all of these various points of contact are established simultaneously when the anchor  500  is vertically installed (see, e.g.,  FIG.  7 B ), although this isn&#39;t strictly necessary. Further, when the anchor  500  is vertically inserted into the lock  400 , tolerances may be such that the planar surfaces  419  and  506  of the lock  400  and the upper portion  502  are bought into contact. While this isn&#39;t strictly necessary, sizing the components in this manner provides for a tight tolerance between the anchor  500  and the lock  400  while still permitting them to be vertically slidable with respect to each other. Notice as discussed earlier that recessing  418  the nut  406  ( FIGS.  5 C and  5 D ) facilitates contacts between planar surfaces  419  and  506 . 
       FIGS.  7 A and  7 B  show use of the door barricading system  90  in both top-down and cross-sectional views. As noted earlier, the receptacle  150  is preferably mounted in the floor  70  just inside the door  10  (e.g. a few centimeters), and proximate to the inside surface  10   b  of the door. The lock  400  has been attached to the door  10  as explained earlier. In  FIG.  7 A , the user has not placed the anchor  500  in the receptacle  150 , and as a result, the door  10  is not barricaded and can be opened (swung outward) by a user inside the door  10 . 
     In  FIG.  7 B , the user has closed the door  10  within frame  12 , and has placed the anchor  500  within the receptacle  150 , which as explained earlier also connects the anchor  500  to the door-mounted lock  400  at keys  416  and  508 . As such, the system  90  provides a barricading function to prevent the door  10  from opening when subject to an external force F, such as that provided by an assailant wishing forced entry. Specifically, attempting to swing the door  10  outward (F) brings the outside surface  10   a  of the door into contact with the stop  412 . The stop  412  is firmly held to the key plate  404  (via nut  406 ), and the key plate  404  is firmly held to the anchor  500  via the keys  416  and  508 . Force F is thus transferred to the lower portion  504  of the anchor  500 , which is firmly held in place within the floor  70 , thus preventing the door  10  from swinging outwards. Of course, should a user decide to open the door  10  at some later time, he can simply remove the anchor  500  from the receptacle  150  ( FIG.  5 A ) and place or store it near the door  10  for later use. 
     Notice that height h 1  of the lower portion  504  ( FIG.  3   ) makes it unlikely that an assailant outside the door  10  could pry the anchor  500  out of the receptacle  150 , such as by attempting to reach under the door with a tool. The significant weight of the anchor  500  also inhibits such external tampering. Furthermore, because the lock  400  is affixed to the door  10  using a mechanism accessible only from the inside of the door  10  (e.g., nut  406 ), an assailant outside the door  10  would not be able to remove the lock  400  (such as by loosening the nut  406 ). Especially given the mechanical strength and thickness of the materials involved, the system  90  will be able to withstand an external force F without breaking. Furthermore, notice that the design of the system  90  is simple, and involves few parts that are easily and cheaply manufactured. Notice also that the lock  400  is attached through the bulk of the door  10  with parts in contact with the door  10  such as stop  412  and key plate  404  having substantial surface areas. This is beneficial compared to other security approaches that merely attach a mechanism to one side of a door (e.g., with screws), which can be a point of weakness that can break in response to the force F. Still further, the system  90  does not involve moving parts (e.g., latches, chains, etc.), which can also break. In short, good and reliable barricading functionality is provided by the system  90  in a cost-effective manner that is easy to manufacture, install, and use. 
     While described as being particularly useful when applied to barricade an outwardly-swinging door  10  as shown, notice that the system  90  also barricades the door should an assailant attempt to force the door inward. Because the surfaces  419  and surfaces  506  of the lock and upper portion  500  can touch, and/or because the overhang  509  can be sized to contact the inside surface  10   b  of the door directly, an inward force on the door will also ultimately be transferred to the lower portion  504  held firmly within the floor. 
     The system  90  as illustrated to this point is configured to barricade the door  10  when the door  10  is closed in its frame  12 . However, the system  90  may be varied to allow the door  10  to be opened slightly while still being barricaded against forced entry.  FIGS.  8 A- 8 D  show a modification to system  90  that permits this. The system  90  is essentially the same as described earlier, but in this example, the bolt  408  is made longer, such as that when the lock  400  is affixed to the door, the stop  412  is not proximate the outside surface  10   a  of the door, as best shown in  FIG.  8 B .  FIGS.  8 C and  8 D  show this modified system  90  in operation.  FIG.  8 C  shows the system  90  when the door  10  is closed in the frame  12 .  FIG.  8 D  shows the system  90  when after the door  10  has been opened slightly. In this configuration, the door eventually hits the stop  412 , which permits the door to be opened by a small gap  108 . Nevertheless, the stop  412  prevents the door from opening further than this, and so the door is barricaded as explained earlier. System  90  of  FIGS.  8 A- 8 D  may be useful in a given application because it barricades the door while still allowing a user on the inside to look through the gap  108  to verify the identity of a person on the outside of the door, and/or to receive an item (e.g., a letter) through the gap while not opening the door completely. 
       FIGS.  9 A and  9 B  show other designs for the anchor  500 .  FIG.  9 A  shows an anchor  500  in which the upper portion  502  is not cylindrical but instead is rectangular. The upper portion  502  retains certain aspects described earlier, such as key  508  and flat surface  506 . However, in this example, the anchor  500  does not include an overhang  509  as shown in earlier examples. Overhang  509  as explained earlier can come into contact with the top of the key plate  404  when the anchor  500  is vertically inserted, although this isn&#39;t strictly necessary because the anchor  500  can bottom out on other surfaces. In  FIG.  9 A , the lower portion  504  is not centered underneath the upper portion  502 , but is instead offset. However, the lower portion  504  could also be centered below the upper portion  502  in other examples. In  FIG.  9 B , the lower portion  504  is not underneath the upper portion  502  at all, and instead a horizontal connecting portion  503  is used to connect these portions, as shown in  FIG.  9 B . Connecting portion  503  may be made of the same materials as the upper and lower portions  502  and  504 , and may be considered as a part of, and may be formed with, either of these portions. 
       FIGS.  10 A and  10 B  show a modification to the lock  400 . In this example, the lock  400  lacks a bolt  408  passing through an opening  13  in the door, and further lacks a stop  412  on the outside surface  10   a  of the door  10 . In effect, the lock  400  as shown in this example comprises only a key plate  404  which is affixed to the inside surface  10   b  of the door. The lock  400  can be affixed in different manners, but in the example shown the key plate  404  includes screw holes  420  to accommodates screws  421  which pass through the holes  420  and affix into the material of the door  10 . Otherwise, the lock  400  operates in conjunction with the anchor  500  (not shown) to barricade the door as explained earlier. This example may not be suitable for all implementations, because it may not be as secure as earlier examples in which the lock  400  includes a stop  412  on the outside of the door  10 : for example, a sufficient external force F may pull the screws  421  from the door. That being said, lock  400  in  FIGS.  10 A and  10 B  may still be suitable for some applications. Furthermore, the lock  400  may be included with or affixable to structures on the inside of the door having sufficient mechanical strength. In one example, the lock  400  may be included as part of a kickplate (not shown) affixed to the bottom inside surface of the door  10 . 
       FIGS.  11 A- 11 C  show another modification to the lock  400 . In this example, the lock  400  again lacks a bolt  408  passing through an opening  13  in the door. However, the lock  400  still includes a stop  412  on the outside surface  10   a  of the door  10 . In this example, the lock  400  includes a horizontal cross member  422  which connects the vertical key plate  404  and the vertical stop  412  around the door. These components may be formed as a single integrated piece, such as milled from a single piece of material, or they may comprise separate affixable components. As best shown in  FIG.  11 A , the lock  400  is essentially C-shaped and can be slipped underneath the door  10 . Specifically, and as shown in  FIGS.  11 A and  11 B , the lock  400  can be slipped underneath the swinging edge  10   e  of the door  10 , such that the horizontal cross member  422  contacts the underside  10   x  of the door, the key plate  404  contacts the inside surface  10   b  of the door, and the stop  412  contacts the outside surface  10   a  of the door. Preferably, the lock  400  is dimensioned such that the inside surfaces of the key plate  404  and stop  412  are spaced at a distance equal to the thickness ‘x’ of the door  10 . In this way, the lock  400  may self-affix to the door by friction, as best seen in the cross section of  FIG.  11 C . Alternatively, the lock  400 , once positioned in placed on the door  10  (relative to the receptable  150 ; not shown), can be affixed to the door using bolts or screws (not shown). Notice as shown in  FIG.  11 C  that the thickness ‘t’ of the horizontal cross member  422  is preferably less than the clearance between the underside  10   x  of the door  10  and the floor  70 . In this way, the lock  400  may be affixed to the door  10  while still allowing the door to swing open. The example of the lock  400  shown in  FIGS.  11 A- 11 C  is advantageous because it provides a stop  412  on the outside surface  10   a  of the door, thus barricading the door when the lock is attached to the anchor  500  (not shown). However, this occurs without the need of drilling an opening  13  through the door  10  to connect the stop  412  to the key plate  404 . Further, while the lock  400  is not subject to tampering from an assailant of the outside of the door, a user inside the door  10  may remove (e.g., slide off) the lock  400  later if so desired, leaving the door unblemished. 
       FIGS.  12 A- 12 C  show another example of how the lock  400  and anchor  500  can be designed. In this example, keys  416  and  508  are not used to connect the lock  400  with the anchor  500 . Instead, the lock  400 , and in particular the key plate  404 , is designed with a channel  430  that passes vertically through the material of the key plate  404 . In the depicted example channel  430  is cylindrical, but could comprise other shapes as well. As before, the key plate  404  includes a horizontal opening  414  to receive a bolt  408  to allow the lock  400  to be affixed to the door, and opening  414  can again include a recess  418  to receive the nut  406  that affixes to the end of the bolt  408 , as better shown in the plan and cross-sectional views of  FIGS.  12 B and  12 C . The channel  430  is designed to pass through the recess  418  in the horizontal opening  414  as best shown in  FIG.  12 C , such that the channel  430  is not obstructed by the bolt  408  and nut  406 . The channel  430  can be viewed as having portions  430   a  and  430   b  above and below the recess  418 , as shown in  FIGS.  12 B and  12 C . As mentioned, the anchor  500  and the key plate  404  do not comprise keys  508  and  416  in this example, but keys could also be included as before. 
     Referring again to  FIG.  12 A , the anchor  500  is designed to slip into and through the opening  430  and into the opening  156  in the receptacle  150  in the floor  70  to barricade the door. In this regard, the anchor  500  as before comprises a lower portion  504  configured to be received by the receptacle  150 , and an upper portion  502  designed to engage the key plate  404  when the anchor  500  is inserted. In the example shown, the anchor  500  comprises a cylinder of a constant diameter in cross section, and thus in this example the upper and lower portions  502  and  504  have equal shapes and sizes in cross section. This facilitates forming the anchor as a single integrated piece. However, this is not strictly necessary, and the upper and lower portions  502  and  504  can have different shapes as before. For example, although not shown, the lower portion  504  may be cylindrical while the upper portion  502  is rectangular. It is preferred that the receiving elements for the anchor  50  be of similar shapes—e.g., that the opening  156  in the receptacle  150  also be cylindrical and that the channel  430  in the key plate  404  also be rectangular. This provides a tight tolerance for the anchor  500  when it is positioned in place to barricade the door, while still allowing the anchor  500  to slide vertically relative to the key plate  404  and the receptacle  150 . That being said, it is not strictly necessary that the portions  502  and  504  of the anchor  500  have the same shape as receiving elements  430  and  156 . 
     Barricading functionality of the system  90  in  FIGS.  12 A- 12 C  is established similarly as in earlier examples. When the anchor  500  is inserted ( FIG.  12 C ) and the door  10  is subject to an external force F, the outside surface  10   a  of the door contacts the stop  412 . The stop  412  is firmly held to the key plate  404  (via nut  406 ), and the key plate  404  is firmly held to the anchor  500  via engagement of the upper portion  502  with the channel  430 . Force F is thus transferred to the lower portion  504  of the anchor  500 , which is firmly held in place within the floor  70 , thus preventing the door  10  from swinging outwards. Should a user decide to open the door  10  at some later time, he can simply remove the anchor  500  from the receptacle  150 . In this regard, a handle  510  may be provided on the top of the anchor  500  to assist a user in inserting and removing the anchor  500  from the lock  400  and receptacle  150 . 
     The design of the anchor  500  and lock  400  in  FIGS.  12 A- 12 C  can ease installation of the system  90  and ensure that the components of the system will properly connect. For example, the lock  400  can be affixed to the door  10 . A drill bit (e.g.,  210 ,  FIG.  17   ) can then be passed through the channel  430  and down to the floor  70  to drill the hole  160  that will receive the receptacle  150 . Because the hole  160  may need to be of larger diameter that the opening to accommodate the receptacle  150 , a second larger diameter drill bit may be used to broaden the hole  160  before insertion of the receptacle  150 . Passing the (initial) drill bit through the opening  430  helps to ensure that the receptacle  150  will be properly aligned with the lock  400 , and thus that the lock  400  and receptacle  150  will be able to smoothly vertically receive the anchor  150  without misalignment. 
     Some doors that a user might wish to barricade may be double doors, with left and right doors  10 L and  10 R that are both openable and potentially vulnerable to forced entry. Variations can be made to the system  90  to allow it to barricade such double doors, and an example is shown in  FIGS.  13 A and  13 B . As shown in  FIG.  13 A , a double-door anchor  500  includes as before an upper portion  502  and a lower portion  504 . The upper portion  502  as before can include a flat surface  506 . However, in this example, two keys  508 L and  508 R are provided on the flat surface  506 . Two corresponding locks  400 L and  400 R are correspondingly affixed to left and right doors  10 L and  10 R. Although the details aren&#39;t shown, these locks  400 L and  400 R may be constructed in any of the manners described earlier, with each including a key  416  to connect with the keys  508 L and  508 R. Thus, when a user desires to barricade both doors, the lower portion  504  is vertically inserted into receptacle  150  (not shown), which simultaneously inserts keys  508 L and  508 R into the keys  416  of the locks  400 L and  400 R, thus barricading the doors  10 L and  10 R against swinging open. 
       FIG.  14    shows further modifications that can be made to the anchor  500 .  FIG.  14    shows that the anchor  500  can be made from components that are affixed together, such as the upper portion  502  and lower portion  504  which in this example comprise separate affixable pieces. As shown, lower portion  504  can include a threaded end  507  that can be screwed into a threaded opening  505  formed on the underside of the upper portion  502 . This may be easier and cheaper to manufacture compared to forming the anchor  500  (upper and lower portions  502  and  504 ) as a single piece. 
       FIG.  14    also shows that electronics can be incorporated with the anchor  500 . In this regard, part of the upper portion  502  can be hollowed out to include an electronics chamber  240  covered by a lid  242 . The lid  242  can include a light source such as a light emitting diode (LED)  244 . This is useful as it allows the anchor  500  to act as a night light, or to otherwise indicate the location of the anchor, which might be useful to prevent a person from tripping on the anchor when it is in use to barricade the door. Although not shown, one skilled in the art will understand that the electronics chamber  240  could include a battery and necessary circuitry (e.g., a circuit board) to run the LED. Further, although not shown, the lid  242  could include an on/off switch to operate the LED  244 . 
     Anchor  500  can also include a pressure sensor  246  to sense a force F that has been imparted to the anchor. The pressure sensor  246  can be positioned on the key  508  or elsewhere on the anchor  500  at a location that is capable of sensing force F. The pressure sensor  246  can be any device capable of sensing force, such as a load cell or an accelerometer. If the sensor  246  and associated electronics detects a force beyond a threshold, i.e., a large force that would suggest that unauthorized entry into the premises is being attempted, the anchor  500  can wirelessly notify the user (e.g., their cell phone) or the premise&#39;s home security system of that fact. In this regard, the electronics in chamber  240  could include telemetry circuitry (e.g., a Bluetooth antenna). 
       FIG.  15    shows that the system  90  can include a cap  170  which a user can use to cover the opening  156  in the receptacle  150  when it is not being used with the anchor  500 . This is useful, as it prevents debris from falling down into the opening  156 . 
       FIG.  16    shows a bracket or other hanging device  180  that can be used to hold the anchor  500  when it is not in use—i.e., when it is not placed in the receptacle  150 . Such a hanging device  180  could be made in many different ways, but as shown includes support  185  with an opening  184 . To store the anchor  500 , the lower portion  504  can be placed though the opening  184 , thus allowing the underside of the upper portion  502  to rest on the support  185 . The hanging device  180  can also include screw holes  182  to allow the device  180  to be affixed to a structure.  FIG.  16    shows that the hanging device  180  can be affixed to the door  10  itself, thus allowing the anchor  500  to be conveniently stored in a location proximate to the receptacle  150  and lock  400  with which it will be used. 
       FIG.  17    shows components that can be included in a kit  200  that is used to sell the system  90  to consumers. The kit  200  can include the anchor  500 , which in this example comprises upper and lower portions  502  and  504  as separate components. The kit  200  can also include the lock  400 , including its individual components, including the key plate  404 , the bolt  408  (which includes the stop  412 ), and the nut  406  used to affix these components to a door  10 . The kit can further include the receptacle  150  and its optional cap  170 , and the hanging device  180  described earlier. The kit  200  can also include items that assist the user with installation of the system  90 . For example, the kit  200  can come with a drill bit  210  that is used to form the hole  160  in the floor  70  that will accommodate the receptacle  150 . The drill bit  210  may be sized appropriately in diameter (D 1 ) and height (H) to match the outer dimensions of the side wall  154  of the receptacle  150 . In this regard, the drill bit  210  may include a shoulder  212  to set the height appropriately. The kit  200  may also include a tube of an adhesive or cementing material  158 , which as noted earlier can be used to affix the receptacle  150  in the hole  160  in the floor  70 . The kit  200  may also include a separate drill bit  214  that is used to form the opening  13  (e.g.,  FIG.  5 A ) in the door  10  as is useful to affixing the lock  400 . The drill bit  214  may be sized appropriately in diameter (D 2 ) to match the diameter of the bolt  408  that passes through opening  13  in the door  10  during the lock  400 &#39;s installation. 
     Lastly  200  the kit may include an installation template  220  which in particular can guide the user as to where he should drill the hole  160  in the floor  70  and the opening  13  in the door. In the example shown, the template  220  comprises a sheet a paper which the user can fold (along the dotted line) and tape to the floor  70  and to the door  10  when it is shut in its frame  12 . The template  220  can then instruct the user to center the drill bit  210  at a point  215 , and to center drill bit  214  at point  216 . The location of points  215  and  216  will depend on the dimensions of the components in the system  90 , which as noted earlier can vary, but will generally be set so that vertically inserting the anchor  500  into the receptacle  150  will simultaneously allow keys  508  and  416  of the anchor  500  and lock  400  to connect. 
     One skilled in the art will understand that the various aspects of the system  90  can be combined in different manners to achieve different advantages. It is neither practical nor necessary to show all such possible combinations. 
     Although particular embodiments of the present invention have been shown and described, it should be understood that the above discussion is not intended to limit the present invention to these embodiments. It will be obvious to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the present invention. Thus, the present invention is intended to cover alternatives, modifications, and equivalents that may fall within the spirit and scope of the present invention as defined by the claims.