Abstract:
A utility cart includes a cabinet with a latch and strike lock, which is unlocked in the presence of a passive near field RFID key device and held open by a latch controller for sufficient time to allow the user to open the unlocked cabinet door. The latch is biased to its locking position, to which it returns when released by the controller. The latch includes a ramp surface which is engaged by the leading edge of the strike as the cabinet door is closed. In this way, the strike pushes the latch out of the way as it passes over the end of the latch, and the biased latch then returns to its locking position engaging a keeper in the strike as the keeper passes into position opposite the latch.

Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of utility carts. 
     BACKGROUND OF THE INVENTION 
     Utility carts typically comprise a wheeled base, a handle, and a set of shelves and/or cabinet in which chemicals, cleaning supplies and other tools can be kept. The cabinets often include a lock which can be unlocked and relocked by means of a key carried by the user of the cart. 
     SUMMARY OF THE INVENTION 
     The utility cart of the present invention includes a cabinet with a latch and strike lock, which is unlocked in the presence of a passive near field RFID key device, and held open by a latch controller for sufficient time to allow the user to open the unlocked cabinet door. The latch is biased to its locking position, to which it returns when released by the controller. The latch includes a ramp surface which is engaged by the leading edge of the strike as the cabinet door is closed. In this way, the strike pushes the latch out of the way as it passes over the end of the latch, and the biased latch then returns to its locking position engaging a keeper in the strike as the keeper passes into position opposite the latch. 
     These and other objects, advantages and features of the invention will be more fully appreciated by reference to the written description of the preferred embodiments, the claims and the appended drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partial perspective view of the utility cart of the preferred embodiment; 
         FIG. 2  is a perspective view of the covered latch and lath controller housing; 
         FIG. 3  is a perspective view of the interior of the latch and controller housing and the housing cover, with the housing removed and with the door handle and strike shown in their locked position by engagement with said latch; 
         FIG. 4  is a view of the latch and controller housing and its contents, with the housing cover removed; 
         FIG. 5  is a perspective view of the side wall of the cart cabinet, showing the opening therein, which exposes the open interior of the latch and controller housing and its contents; 
         FIG. 6  is a plan view of the latch controller, door and strike mechanism, with the housing removed and without showing the cabinet; 
         FIG. 7  is a fragmentary plan view of the latch mechanism; 
         FIG. 8  is a fragmentary perspective view of the latch mechanism; 
         FIG. 9  is a control schematic: 
         FIG. 10  is a perspective view showing a near field RFID key card being positioned near the antenna of said latch controller; and 
         FIG. 11  is a perspective view of the cabinet door being opened. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Table 1 below lists the components of the preferred embodiments. Utility cart  1  includes a wheeled platform  2  and a cabinet  3  having a hinged cabinet door  4  ( FIG. 1 ). A handle and strike member  10  is secured to the edge of door  4  ( FIGS. 1, 10 ). A housing  6  containing a latch  20 , latch actuator  30 , controller  40  and a battery  50  is secured to the inside of cabinet sidewall  3   a , adjacent an opening  3   b  ( FIGS. 3-5 ). A cover plate  5  is fitted to the sidewall of cabinet  3  to cover opening  3   a , and to cover the open side of housing  6  ( FIGS. 1, 2 ). Controller  40  comprises a micro controller board  41  operably attached to an antenna board  42  which is located adjacent opening  3   b  in sidewall  3   a  of cabinet  3  ( FIGS. 4, 5 ), and is covered by cover plate  5  ( FIGS. 1, 2 ). To open door  4  of cabinet  3 , one places a near field RFID card  8  adjacent cover plate  5 . This allows communication with antenna  42  which causes the micro controller board  41  to activate actuator  30 , releasing latch  20  and holding it for sufficient time to allow a user to open door  4  using handle  10  as shown in  FIGS. 10 and 11 . 
     
       
         
               
             
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Component Listing 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Cart 
                  1 
               
               
                   
                 Wheeled base 
                  2 
               
               
                   
                 Cabinet 
                  3 
               
               
                   
                 Cabinet door 
                  4 
               
               
                   
                 Cover plate 
                  5 
               
               
                   
                 Pin hole 
                  5a 
               
               
                   
                 Controller/latch housing 
                  6 
               
               
                   
                 Inside wall 
                  6a 
               
               
                   
                 Detent aperture 
                  6b 
               
               
                   
                 Slot opening 
                  6c 
               
               
                   
                 Antenna mounts 
                  6d 
               
               
                   
                 Cover plate mounts 
                  6e 
               
               
                   
                 Pivot mount peg 
                  6f 
               
               
                   
                 Fasteners 
                  7 
               
               
                   
                 RFID key card 
                  8 
               
               
                   
                 Handle/Strike 
                 10 
               
               
                   
                 Handle flange 
                 11 
               
               
                   
                 Handle mount 
                 11 
               
               
                   
                 Spacer flange 
                 13 
               
               
                   
                 Strike 
                 14 
               
               
                   
                 Keeper 
                 15 
               
               
                   
                 Latch 
                 20 
               
               
                   
                 Pivot pin 
                 21 
               
               
                   
                 Latch arm 
                 22 
               
               
                   
                 Detent 
                 23 
               
               
                   
                 Detent ramp 
                 23a 
               
               
                   
                 Detent locking ramp 
                 23b 
               
               
                   
                 Tail 
                 24 
               
               
                   
                 Bias spring 
                 25 
               
               
                   
                 Actuator 
                 30 
               
               
                   
                 Actuator arm 
                 31 
               
               
                   
                 Controller 
                 40 
               
               
                   
                 microcontroller board 
                 41 
               
               
                   
                 Antennae board 
                 42 
               
               
                   
                 Led indicator 
                 43 
               
               
                   
                 Battery 
                 50 
               
               
                   
                   
               
             
          
         
       
     
     Handle and strike  10  is preferably bent from a piece of metal and comprises a handle flange  11  which a person engages to open door  4  ( FIGS. 1, 3 &amp; 11 ). Flange  11  extends at right angles from a flange  12  which is secured to the edge of cabinet door  4  ( FIGS. 1, 6 ). Flange  13  extends from mounting flange  12  at right angles and is also secured to cabinet door  4  on the inside surface thereof ( FIG. 6 ). Finally, strike flange  14  extends perpendicularly from flange  13  and includes a keeper opening  15  therein ( FIGS. 3, 6 ). 
     Housing  6  is an open sided tray like housing, comprising a perimeter edge wall and an inside wall  6   a . The various components contained in housing  6  are directly or indirectly mounted to inside wall  6   a  of housing  6  ( FIG. 4 ). Corner bosses  6   e  facilitate the mounting of housing  6  to the sidewall  3   a  of cabinet  3 , using fasteners  7  ( FIGS. 4, 5 ). Housing  6  is secured to the inside of cabinet side wall  3   a , such that the open side of housing  6  faces the opening  3   b  in cabinet side wall  3   a  ( FIG. 4 ). 
     Latch  20  is pivotally mounted on pivot pin  21  which is fixedly mounted within housing  6 , on peg  6   f  which projects from housing inside wall  6   a  ( FIGS. 3, 8 ). Latch  20  includes a horizontal arm  22  which pivots about pivot pin  21 , and includes a detent member  23  projecting from one end thereof for engagement with keeper aperture  15  ( FIGS. 3, 6 ). Arm  22  extends from detent  23  past pivot pin  21  to a downwardly depending tail  24  ( FIGS. 3, 6, 7 &amp; 8 ). 
     Latch  20  is normally biased into its locking position by bias spring  26 . Bias spring  25  coils around pivot pin  21  and includes an extending leg  25   a , the end of which is seated in a groove  24   a  in the downwardly extending tail  24  of pivot arm  12  ( FIGS. 3, 7 &amp; 8 ). After wrapping around pivot pin  21 , another extending leg  25   b  rests against the inside of inside wall  6   a  of housing  6 , thereby biasing latch  20  such that its detent end  23  projects through an aperture  6   b  in inside wall  6   a  of housing  6  ( FIG. 7 ). Referring to  FIG. 8 , it can be seen that during assembly, projecting leg  25   b  actually extends through a slot opening  6   c  in inside wall  6   a  of housing  6 . During assembly, leg  25   b  is tucked down through slot opening  6   c  and is pushed to the side of slot  6   c  so that it engages the inside of inside wall  6   a . When strike  14  is in its locking position, detent end  23  is also biased to extend into keeper opening  15 , thereby locking cabinet door  4  ( FIGS. 3, 6 ). 
     Latch actuator  30  is a servo motor which includes a pivotally moving arm  31 . Arm  31  engages tail  24  of latch  20  pivots latch  20 , such that detent  23  is pivoted out of keeper aperture  15  in strike plate  14 , unlocking door  4 . Controller  40  holds arm  31  in its unlocking position long enough for a user to open door  4 , as shown in  FIG. 11 . Actuator  30  is then released, arm  31  retracts, and latch  20  is biased back into its locking position by bias spring  25 . 
     However, door  4  will typically be open when latch  20  returns. To facilitate re-locking of door  4 , detent  23  on latch  20  includes an outwardly facing ramp surface  23   a , which when latch  22  is positioned in its locked position as shown in  FIGS. 3 and 6 , allows strike plate  14  to slide over ramp surface  23   a  as one is closing door  4 , thereby pushing detent  23  away from strike plate  14  and allowing it to pass over the end of detent  23  and be biased back into position within keeper aperture  15  as shown in  FIGS. 1 and 6 . The inside surface  23   b  of detent  21  is also sloped so as to make an acute angle with respect to arm  22 , thereby providing a secure catch of strike plate  14  and making, it very difficult for one to accidentally cause strike plate  14  to be slid over detent  23  when latch  20  is in its locking position. 
     Controller  40  comprises microcontroller  41  connected to antenna board  42 . Antenna board  42  is mounted by suitable fasteners on bosses  6   d  extending from inside wall  6   a  ( FIG. 4 ). When so mounted, antenna board  42  is positioned in front of opening  3   b  in cabinet side wall  3   a  ( FIG. 4 ). This improves the ability of antenna board  42  to communicate with near field RFID card  8 . 
     Battery  50  is mounted in housing  6 , and can be serviced through a removable covered opening in inside wail  6   a  of housing  6 , or by removing cover plate  5 , creating access to battery  50  though opening  3   b  in cabinet side wall  3   a  ( FIG. 4 ). Battery  50  is electrically connected to and provides power to microcontroller  41  ( FIG. 9 ). Micro controller  41  provides power to an RFID controller subunit  41   a , which provides power and instructions to antenna  42 , and in turn receives information from antenna  42  which antenna  42  receives from an activated near field RFID key card ( FIG. 9 ). Microcontroller  41  is also electrically connected to and provides instructions to a red/green bi-colored indicator led  43  ( FIG. 9 ), which is visible through a clear lens in cover  5  ( FIG. 2 ). Micro controller is electrically connected to and sends instructions to actuator  30  ( FIG. 9 ). 
     RFID controller  41   a  instructs antenna  42  to emit a continuous or intermittent signal which will be picked up by a near field RFID card  8  placed in close proximity to antenna  42 . If the signal is transmitted intermittently, it must stay “on” sufficiently long to be picked up by a near field RAID card  8  placed in proximity to antenna  42  ( FIGS. 9, 10 ), and to power through induction to coil in card  8  a return coated signal from card  8 . RFID card  8  is then powered through induction by the antenna signal, and responds to the antenna signal by sending a coded signal to RFID controller  41   a  through antenna  42 . If the coded signal matches the coded information recorded in RFID controller  41   a , microcontroller  41  causes the bi-colored LED light  43  to glow green ( 43   a  in  FIG. 9 ), indicating that latch  22  will be unlocked and door  4  can be opened. If the signal from RFID card  8  does not match the code information in RFID controller  41   a , microcontroller  41  causes bi-colored LED light  43  to glow red ( 43   b  in  FIG. 9 ), indicating that latch  22  is not in its unlocked position and door  4  cannot be opened. When the RFID controller  41   a  senses a match with the RFID key card, micro controller  41  sends power to servo actuator  30 , which rotates servo arm  31  and causes latch  22  to pivot into its unlocking position. 
     Microcomputer board  42  includes a delay function which holds servo arm  31  and latch  22  in its unlocked position long enough for the user to grasp handle flange  11  and open door  4  ( FIG. 11 ). Preferably, the delay is from about 2 to 10 seconds, more preferably about 2-5 seconds, and most preferably about 3 seconds. The timer circuit then times out and bias spring  25  biases latch  22  back into its locked position, though with door  4  open so that detent  23   a  is not engaging the keeper in strike  14 . 
     After completing his work, the user simply closes door  4  such that strike flange  14  slides over ramp  23   a , pushing latch  22  out of the way, until keeper aperture  15  is located over the end of detent  23 , at which point biasing spring  25  forces latch  22  back into its locking position with detent  23  extending through keeper aperture  15 . 
     To accommodate loss of power caused by a dying or faulty battery, cover plate  5  is provided with a pin hole  5   a  ( FIG. 2 ), which is aligned with the tail end  24  of latch arm  22 . This allows a user to insert a slender rod and engage and push tail end  24  away, pivoting latch  22  into its opening position. 
     Of course, it is understood that the foregoing discloses preferred embodiments of the invention, and that various changes and alterations can be made without departing from the breadth and spirit thereof as set forth in the appended claims.