Abstract:
Apparatus for providing a signal in response to the actuation of an internal lock mechanism for a door latch to a locked condition of the door latch and for detecting the locked condition when the door is in a closed position with the door latch bolt in the door jamb. Detection apparatus is located in the door jamb and senses the lock signal and in turn can provide a signal locally or to a remote security or surveillance system indicating the locked or unlocked condition of the latch bolt when the door is in the closed position.

Description:
FIELD OF THE INVENTION 
     The present invention relates to sensor systems for detecting the locked or unlocked condition primarily for openings such as doors for homes and buildings. 
     BACKGROUND OF THE INVENTION 
     It is well established to provide means to detect the locked or unlocked condition of a door and to transmit a signal indicative of this condition to a central or local alarm or surveillance system. With doors such sensing is commonly done by detection of the position of a dead bolt. Many conventional locks for doors, however, do not utilize dead bolts for locking but instead provide locking by an internal lock of the door latch bolt or door knob. In the present invention a simple system is provided in which a signal is generated upon actuation of the lock for the latch bolt. At the same time, however, detection apparatus is provided in the door jamb in the door frame such that the locked condition is sensed only when the door is closed and the latch bolt is located in the door jamb. Now the signal can be readily transmitted to a central alarm or surveillance system or a local display whereby an indication will be provided of the locked or unlocked condition of the latch bolt and hence of the door when the latch bolt is engaged in the door jamb. 
     The apparatus of the present invention being of a relatively simple construction can be made to readily replace existing door latch assemblies as a retrofit. In addition it can be applied to some existing door latch assembly designs. 
     SUMMARY OF THE INVENTION 
     In one form of the present invention, the signal generating and detecting apparatus utilizes a permanent magnet which is pivotally mounted in a door latch assembly within the door. Upon actuation of the lock for the latch bolt the magnet is pivoted into alignment with a magnetic circuit that extends through the latch bolt. A detector, such as a reed switch, is located in that part of the magnetic circuit in the door jamb and will sense the presence and locked condition of the latch bolt when the magnetic field is energized by the pivotal location of the magnet into the magnetic circuit in response to actuation of the lock. 
     In a preferred form of the invention, magnetic signal generating detection apparatus is used in a compact construction readily adaptable for a conventional door latch assembly. However, as will be seen other forms of non-contact signal generating and detecting apparatus may be used. 
     Thus it is an object of the present invention to provide a contactless detection system for a door latch assembly for detecting and providing a signal upon closure of a door and placing the latch bolt in a locked condition. 
     It is another object of the present invention to provide a contactless detection system utilizing a magnetically actuated circuit for detecting and providing a signal upon closure of a door and placing the latch bolt in a locked condition. 
     It is still another object of the present invention to provide a contactless detection system adaptable for use with door latch assembly designs of generally conventional constructions and for detecting and providing a signal upon closure of a door and placing the latch bolt in a locked condition. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood and apparent from the detailed description and the appended claims, taken in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a top elevational view of a generally conventional door latch assembly modified to include the lock sensor alarm system of the present invention with some parts shown in section and others shown broken away and with a reed switch shown in phantom and includes a pair of door knob subassemblies with a key lock actuated door knob subassembly shown on one side and a non-key, ribbed pivot button lock actuated subassembly shown in phantom on the opposite side; 
     FIG. 2 is a perspective view of the door latch assembly of FIG. 1 showing only the key actuated door knob subassembly; 
     FIG. 3 is an exploded perspective view of the portion of the door latch assembly of FIG. 2; 
     FIG. 4 is a top elevational view of the key lock actuated door knob subassembly of FIG. 1 in the locked condition; 
     FIG. 5 is a sectional view of the door knob subassembly of FIG. 4 taken along the lines  5 — 5  in FIG.  4  and showing the lock in the actuated locked condition with a sensor actuating pivot plate shown in phantom in its locked sensing position; 
     FIG. 6 is a top elevational view similar to FIG. 4 with the key lock deactuated to the unlocked condition with the sensor actuating pivot plate shown in phantom in its unlocked sensing position; 
     FIG. 7 is a sectional view taken along the lines  7 — 7  in FIG.  6  and showing the lock in the deactuated condition; 
     FIG. 8 is a side elevational view of the door latch assembly of FIG. 1 taken generally along the lines  8 — 8  in FIG.  1  and with some elements shown in section; 
     FIG. 9 is an enlarged, fragmentary elevational view taken in the Circle  9  in FIG.  8  and depicting a part of the magnetic actuator; 
     FIG. 10 is an end view of the door latch assembly taken generally in the direction of the Arrow  10  in FIG. 1 but with the opposite door knob apparatus shown in solid lines and also showing the location of the reed switch used to detect a locked or unlocked condition; and 
     FIG. 11 is a side elevational view of the door latch assembly similar to FIG. 8 showing the key actuated door knob apparatus in the closed and locked condition with the magnetic detection apparatus in the locked condition and with the magnetic circuit shown in shaded lines and with the related elements of the door latch assembly shown in phantom lines. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Looking now to the drawings, it can be seen that the basic construction of the door latch assembly is of one well known in the art. As will be seen, however, the present invention provides a unique lock sensor detection system for use in general with basic door latch assemblies with relatively minor changes. In this regard the door latch assembly shown by way of example, has the basic construction of a form made by D.S. &amp; A. Inc. and sold under Part No. 51073 and except for the changes as described is of that basic construction. A similar unit is made and sold by Kwikset Corporation. 
     In FIG. 1, the door latch assembly  10  is shown mounted to a door  12  (shown in phantom) and includes a first door knob subassembly  14  mounted on one side of the door  12  and a second door knob subassembly  16  (shown in phantom) mounted on the opposite side of the door  12 . The first door knob subassembly  14  includes a rotatable door knob  18  mounted to the door  12  by connection with a generally circular face plate  20 . Similarly, the second door knob subassembly  16  includes a rotatable door knob  22  mounted to the door  12  by connection with a second generally circular face plate  24 . In this regard, the first and second knob subassemblies  14  and  16  are held to the door  12  in operative alignment with each other by means of the interconnection of two threaded bolts  26  extending through face plate  24  and being threadably engaged with two internally threaded studs  28  connected to the face plate  20 . The face plates  20  and  24  are formed with relatively shallow cavities on their inner sides. 
     Looking now to FIGS. 1-3 and  8 , a semicircularly shaped rotator shaft  30  is rotatably connected to the first knob  18  and extends through the door  12  and into rotatable engagement with the second knob  22 . In this way rotation of either door knob  18 ,  22  will rotate the other by way of the rotator shaft  30 . As will be seen the diametrically opposite edges  31  of the rotator shaft  30  are used for engagement with driving components with the door knobs  18 ,  22  and also with selectively actuable locking components, to be described, whereby rotation of door knobs  18 ,  22  will be prevented when the door latch assembly  10  is placed in its locked condition. 
     A latch assembly  29  includes an elongated latch bolt  32  supported in a housing subassembly  40 . Either of the door knob subassemblies  14  and  16  are mounted for driving a latch assembly generally indicated at  29  within the door  12  to move a latch bolt generally indicated at  32  and an anti-tamper rod generally indicated at  33  from extended to retracted and from retracted to extended positions at a door edge generally indicated at  35 , again, all in a usual manner. The anti-tamper rod  33  is resiliently movable relative to the latch bolt  32  to inhibit tampering with the latch bolt  32  from outside of the door  12 . As pointed out, the principles of the present invention relate to a lock sensor detection system so that the door knob subassemblies  14  and  16 , and the latch assembly  29  including the latch bolt  32  and anti-tamper rod  33  may generally be of conventional constructions adaptable for satisfying the interaction of the combinations but with modifications for the sensing operation to be described and thus certain details thereof have been omitted for purposes of simplicity and brevity. 
     The latch bolt  32  has a nose portion  38  adapted to be movably located in an opening  34  in a door jamb  36  whereby the door  12  can be opened or closed. In this regard the outer nose portion  38  is tapered on one side to facilitate closure from one side and is substantially flat on the opposite side to block opening of the door  12  by pushing in that direction when located in the door jamb opening  34 . In this regard a molding  39  is fixed to the wall of the door jamb  36  in a position to engage the door  12  on the tapered side of the nose portion  38  to prevent excessive movement of the door  12  in that direction after the nose portion  38  is located in the door jamb opening  34 . As can be seen in FIGS. 1 and 3 the latch bolt  32  is supported in housing subassembly  40  with the nose portion  38  operatively connected to an inwardly extending, generally flat extension plate  52  which in turn is movably connected to a generally flat drive plate  42 . The anti-tamper rod  33  is of a conventional construction noted and does not interact with the lock sensor detection system and hence the details thereof have been omitted. 
     The housing subassembly  40  includes a generally cylindrical housing section  44  in which the latch bolt  32  is slidably supported. The drive plate  42  has an elongated center opening or slot  41  to provide clearance with the outer one of the threaded studs  28 . The extension plate  52  of the latch bolt  32  is attached to the inner end of the latch bolt nose portion  38  and extends axially inwardly therefrom and into the housing section  44 . At the same time the extension plate  52  has a stud  55  which extends transversely into the slot  41  whereby the extension plate  52  and hence latch bolt  32  will be moved to the retracted position by inward movement of the drive plate  42 . The latch bolt  32  is normally resiliently biased with its nose portion  38  extending outwardly by a spring (not shown) inside of the cylindrical housing section  44  to bias it outwardly. In this regard the connection of the drive plate  42  to the latch bolt extension plate  52  by engagement of the stud  55  in the slot  41  provides a lost motion type connection which permits the latch bolt  32  to be moved inwardly, independently of movement of the drive plate  42 , to its retracted position against the bias of the spring. In this regard, the extension plate  52  has an open slot  53  at its inner end to provide clearance with the outer stud  28  when in the retracted position. Thus the nose portion  38  is resiliently movable inwardly relative to the drive plate  42  to facilitate closure of the door  12  without need to actuate the door knob subassemblies  14  or  16 . The drive plate  42  has a generally semi-circular opening  56  which receives in mating engagement the semi-circular contour of the rotator shaft  30  with engaging contact of the edges  31  with the flat ends  57  of the semi-circular opening  56 . Thus rotation of the rotator shaft  30  in a clockwise or counterclockwise direction by either door knob  18  or  22  will result in rearward movement of the drive plate  42  causing retraction of the latch bolt  32  and movement of the nose portion  38  out from the door jamb opening  34  whereby the door  12  can be opened. At the same time the rotator shaft  30  and hence the drive plate  42  are normally biased by a coil spring  54  to their neutral, non-actuated positions to permit the latch bolt  32  with its nose portion  38  to be resiliently maintained in its normally outwardly extended position from the cylindrical housing section  44  for closure. End arms  58  extend radially oppositely from the body of the coil spring  54  to engage stop brackets  59  secured to the face plate  20  within its cavity. 
     The door latch assembly  10  is adapted to be locked by a key  64  applied through a key hole in the door knob  18  (keyhole not shown). Here the key  64 , upon insertion into the key hole, will be in operative engagement with a lock shaft  60 . The lock shaft  60  is of a tubular construction and has a generally square shaped engagement opening  62 . A key actuated connector  63  is matably connected to the adjacent end of the lock shaft  60  and is adapted to be rotated by rotation of the key  64  to selectively rotate the lock shaft  60  to a locked or unlocked position. At the same time the opposite door knob subassembly  16  has a rotatable ribbed pivot button  69  in the door knob  22  which is connected to the opening  62  at the opposite end by a mating lock shaft  73 . Thus the lock apparatus can be actuated from either side of the door  12 . However, it should be noted that the key actuated door knob subassembly  14  will be located on the outer side of the door  12  while the pivot button actuated door knob subassembly  16  will be on the inner side of the door  12 . It should again be noted that the actuating connection between the door knob subassemblies  14  and  16 , the latch bolt  32  and the lock apparatus can be of a conventional structure well known in the art, such as in the Part No. 51073 previously noted. Thus since the specific details of such actuating connection and lock apparatus do not constitute a part of the present invention such details have been omitted with the actuating connection and lock apparatus shown mainly generally for purposes of brevity and simplicity. 
     In the locked condition the rotator shaft  30  will be blocked from rotation. Looking now to FIGS. 4 and 5, this occurs by radially outward movement of a pair of locking tabs  66  by rotation of the lock shaft  60  by the key  64  or pivot button  69 . The locking tabs  66  will be moved radially outwardly to opposite sides of the axially innermost end of the base  65  of the inner stud  28 . The locking tabs  66  are part of a slidable lock plate  67  which is rotatably supported in a drive housing assembly  75 . The lock plate  67 , however, is connected to the lock shaft  60  by a cam type engagement member  81  whereby rotation of the lock shaft  60  by key  64  or pivot button  69  will move the lock plate  67  with the locking tabs  66  in translation radially outwardly to a locked condition or radially inwardly to an unlocked condition. In FIG. 11 the cam engagement member  81  is shown in the locked condition with the unlocked condition shown in phantom lines. The drive housing assembly  75  in turn is in rotatable engagement with the edges  31  of the rotator shaft  30 . Thus the lock plate  67  will also be rotated by the rotator shaft  30 . However, when the lock plate  67  is actuated to move the locking tabs  66  into locked engagement with the base  65  of the stud  28 , rotational movement of the drive housing assembly  75  and hence of the rotator shaft  30  is prevented thereby locking the latch bolt  32  from actuation by the door knobs  18  and  22 . It should be noted that the opposite door knob  22  could be provided with a similar keyhole and connection to a key actuated rod whereby the door latch assembly  10  can be key locked or unlocked from either side of the door  12 . Such construction is well known in the art and hence is not shown. 
     The housing subassembly  40  includes a generally Ushaped channel section  68  which is attached at its open end to the inner end of the cylindrical housing section  44 . The channel section  68  has a slot  70  at its closed end and a through bore  71  spaced from its open end both of which are adapted to receive the studs  28  to facilitate alignment and support of the housing subassembly  40  with the knob subassemblies  14  and  16 . At the same time the channel section  68  has enlarged, generally semi-circular, in line through openings  77  to receive in clearance relationship the rotator shaft  30  and lock shaft  60 . In this regard the openings  77  terminate in generally flat edges  79  which are engaged by the edges  31  of the rotator shaft  30  at the end of full rotation to provide a stop when the latch bolt  32  has been fully withdrawn from the door jamb opening  34 . 
     Again, as noted, the above described construction is well known in the art and hence specific details thereof have been omitted for purposes of brevity and simplicity. In this regard as noted, the present invention is directed to a contactless detection system for detecting the locked or unlocked condition of the door latch assembly and also to facilitate use of such detection in a central or local alarm or surveillance system. 
     Looking now to FIG. 3, the magnetic detection apparatus as shown includes a support plate  74  which is of a generally C-channel section and has a pair of flanges  76  at its open side adapted to hold the plate  74  onto the channel section  68  for selective slidable movement. The support plate  74  can thus be selectively and readily moved to the desired position by the sliding engagement. See FIGS. 2 and 8. The support plate  74  has a central bore  78  adapted to receive the rotator shaft  30  and the lock shaft  60  in clearance relationship. An actuating arm  80  has a magnet carrier arm portion  82  and an engagement arm portion  87  extending angularly from the carrier arm portion  82 . The actuating arm  80  is pivotally secured by a fastener  83  to the upper surface of the support plate  74  at the juncture of the carrier arm portion  82  and engagement arm portion  87 . A permanent magnet  84  is secured to the outer end of the magnet carrier arm portion  82  by means of its location in a central slot in the magnet  84 . The magnet  84  is polarized with its north pole (N) on its upper surface and its south pole (S) on its lower surface. See FIG.  9 . As noted the magnet carrier arm portion  82  is angulated relative to the engagement arm portion  87  such as to locate the magnet carrier arm portion  82  and hence magnet  84  in the desired actuated and deactuated positions to be described. In this regard, a coil spring  85  is connected from a stud  89  on the carrier arm portion  82  to a stud  95  at the corner on the top of the support plate  74 . The connecting studs  89  and  95  are selectively angularly offset from each other such that the spring  85  will normally bias the actuating arm  80  and hence the magnet carrier arm portion  82  and magnet  84  to the deactuated position. 
     As biased, the engagement arm portion  87  extends axially towards the face plate  20  and has a pivot plate  88  connected at its inner end which plate  88  is located in line with one of the locking tabs  66 . See FIGS. 5 and 7. Now when the lock shaft  60  is key actuated to the locking position it moves the lock plate  67  and hence tabs  66  radially outwardly with the one tab  66  moving into engagement with the pivot plate  88 . This overcomes the bias of the spring  85  and moves the pivot plate  88  outwardly causing the actuating arm  80  to pivot the magnet carrier arm portion  82  and magnet  84  to the actuated position in a magnetic detection circuit. See FIGS. 4 and 5. Of course, upon actuation of the lock shaft  60  to the unlocked position the tabs  66  will be retracted and the spring  85  will return the magnet carrier arm portion  82  and magnet  84  to the deactuated position. See FIGS. 6 and 7. 
     The magnetic detection circuit includes the upper connecting bolt  93  which is adapted to engage an outer face plate  91  with the lower connecting bolt  99  similarly engaged with the face plate  91  to mount the latch assembly  29  to the door  12 . The upper connecting bolt  93  is also a magnetic conductor. The face plate  91  is generally rectangular in contour and of a generally known construction for fitting into the opening in the edge of the door  12  to support the latch assembly  29  including the latch bolt  32  and its housing subassembly  40 . The inner end of the connecting bolt  93  is selected to extend inwardly sufficiently to be proximate to and overlay the upper or north pole surface of the magnet  84  when it is pivoted to its actuated position in response to locking action. An elongated ridge  94  is located on the upper end of the drive plate  42  to be proximate to the lower or south pole surface of the magnet  84  when in its actuated position. This spaces the remainder of the upper end of the drive plate  42  farther from the upper connecting bolt  93  and thereby assists in optimizing the flow of magnetic flux in the desired path of the magnetic circuit. At the same time the drive plate  42  is located in close proximity or sliding engagement with the extension plate  52 . As will be seen this provides for a low reluctance magnetic connection between the drive plate  42  and extension plate  52  and hence with the latch bolt nose portion  38 . 
     The drive plate  42 , latch bolt  32  including nose portion  38  and extension plate  52  and connecting bolt  93  are constructed of materials of a generally high magnetic permeability or low magnetic reluctance. In contrast the adjacent members including the face plate  91  are constructed of materials having a low magnetic permeability or high reluctance to inhibit diversion of the magnetic field. Thus the noted components provide a defined magnetic path for the magnet  84  when in its actuated position for lock detection. 
     Looking now to FIGS. 8 and 11, a reed switch  98  or other type of magnetic detector is located in the door jamb  36  at a position proximate to the nose portion  38  of the latch bolt  32  when it is in the door jamb opening  34  when the door  12  is closed. 
     The reed switch  98  then is located in the path of the magnetic field between the nose portion  38  of the latch bolt  32  and the connecting bolt  93 . The magnetic field is generally shown by the dashed lines in FIG.  11 . Thus when the door latch assembly  10  is placed in the locked position the magnet  84  is moved into proximity between the ridge  94  of drive plate  42  and upper connecting bolt  93  thereby magnetically energizing the magnetic path noted which then will be detected by the reed switch  98 . The reed switch  98  can be connected by conductors  100  and  102  to a signal, alarm, and/or surveillance system to provide an indication, signal or alarm as to the locked or unlocked condition of the door  12 . Such signal, alarm and/or surveillance systems are well known in the art and hence the details of such system have been omitted for purposes of simplicity and brevity. 
     Thus the lock detection system of the present invention will provide a locked condition signal only when the door  12  is closed and the latch bolt  32  is located in the door jamb opening  34  with the lock actuated. 
     It should be noted that the features of the present invention could be utilized with other non-contact type detectors and energy generators. In this regard it should also be noted that while the door latch assembly  10  is shown to be actuated by doorknobs  18  and  22 , handle type actuators could be used. Also while a key actuated lock is shown and described, as previously noted, other types of lock actuation could be employed, such as lever, push button, etc. 
     Also while actuation of the magnetic circuit is done by pivotal action such as by the actuating arm  80 , actuation could be done by translational movement. In this regard, actuation could be provided by a movable magnetic transmitter with the magnet held stationary. 
     In addition, while detection of the locked condition is done by pivotal movement of the permanent magnet  84  into a position to activate the magnetic circuit it should be understood that the magnet  84  could be fixed and a magnetic insulator and conductor or shunt could be alternatively located in the circuit relative to the magnet  84  to open or close the magnetic circuit. 
     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.