Abstract:
A locking system for a cart having at least one drawer movable between an open position and a closed position. The locking system includes a cam that is movable between a locked position, wherein the drawer of the cart is prevented from moving between the closed and open positions, and an unlocked position, wherein the drawer is released for movement between the closed and open positions. A manually actuated lock mechanism is coupled to the cam and is operable to move the cam between the locked and unlocked positions. An electronically actuated lock mechanism cooperates with the manually actuated lock mechanism to permit automatic operation of the locking system.

Description:
FIELD OF THE INVENTION 
     This invention pertains to carts with lockable drawers, and more particularly to a locking system for medical carts. 
     BACKGROUND OF THE INVENTION 
     Carts with lockable drawers are used for many applications. For example, a medical cart having lockable drawers is used to administer medication to patients in hospitals or other care facilities. A typical medical cart has casters located at the bottom of the cart to permit easy movement of the cart by attending nurses to various patients&#39; rooms. The cart also has one or more drawers for storing patients&#39; medicines. Typically, each drawer is dedicated to storing the medication for an individual patient. Because the cart is used to store medications for several patients and is movable from room to room, controlling access to the contents of the cart to prevent theft or misuse of medication, and thereby protect the patients is important. One such medical cart, as described above, is disclosed in U.S. Pat. No. 5,743,607 to Tuefel et al., which patent is commonly held by the Assignee of the present invention and hereby incorporated by reference in its entirety. 
     Conventional medical carts have manually actuated locks which are operable to permit users to selectively lock and unlock the drawers of the cart to thereby control access to the contents stored in the drawers. Conventional medical carts have also been provided with electronically actuated locks, whereby the drawers of the cart are unlocked in an automated fashion after a user enters an access code into a keypad located on an external portion of the cart. When medical carts have been provided with both manual and electronically actuated lock mechanisms, these mechanisms have typically been provided as separate and independent systems, each individually capable of releasing the drawers of the cart from a locked condition. Because the manual and electronically actuated systems are separate, this necessarily adds to the overall complexity and cost of the carts. 
     There is thus a need for a simple cart locking system which overcomes drawbacks of the prior art such as those described above. 
     SUMMARY OF THE INVENTION 
     The present invention provides a locking system for a cart wherein a manually actuated lock mechanism is integrated with an electronically actuated lock mechanism to provide a compact and efficient system for controlling access to the contents of the drawers of a cart. It is recognized that unlocking the drawers of a cart using an electronically actuated lock mechanism may be initiated, for example, when a user manually enters an access code into a keypad. Accordingly, reference to the lock mechanisms as “manually actuated” and “electronically actuated,” as used herein, is intended to describe the structure or manner in which the respective lock mechanisms operate to unlock the drawers of a cart. 
     In an exemplary embodiment, the locking system includes a cam that is operatively coupled to a drawer of the cart to permit the drawer to be secured within the cart. The cam has a locked position wherein the drawer is prevented from being moved from the closed position to the open position, and an unlocked position wherein the drawer is released for movement from the closed position to the open position. 
     The locking system further includes a manually actuated lock mechanism and an electronically actuated lock mechanism. The manually actuated lock mechanism is operable to permit manual manipulation of the cam between its locked and unlocked positions. In one embodiment, the manually actuated lock mechanism comprises a lock core that is manually movable between a first position corresponding to the locked position of the cam, and a second position corresponding to the unlocked position of the cam. 
     The electronically actuated lock mechanism cooperates with the manually actuated lock mechanism to permit automatic operation of the locking system as desired. The electronically actuated lock mechanism may be actuated when a user enters an appropriate access code into a keypad on the cart, or may be actuated by a control system of the cart according to predetermined conditions. In an exemplary embodiment, the electronically actuated lock mechanism comprises a release member engageable with the lock core of the manually actuated lock mechanism to permit automatic movement of the lock core between its first and second positions, i.e., from the locked position toward the unlocked position, or from the unlocked position toward the locked position. In another exemplary embodiment, the electronically actuated lock mechanism comprises a drive motor coupled to the release member and configured to selectively move the release member in directions toward the respective first and second positions of the lock core. 
     In another aspect of the invention, a method of securing contents in a drawer of a cart having a locking system as described above, comprises selectively moving the manually actuated lock mechanism from a locked condition to an unlocked condition to release a drawer of the cart for movement between closed and open positions. In one embodiment, the method includes manually moving the manually actuated lock mechanism from the locked condition to the unlocked condition. In another embodiment, the method includes automatically moving the manually actuated lock mechanism from the locked condition to the unlocked condition. 
     These and other objects, advantages, and features of the invention will become more readily apparent to those of ordinary skilled in the art upon review of the following detailed description of various exemplary embodiments, taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the invention. 
         FIG. 1  is a perspective view of a medical cart including a locking system incorporating features of the present invention; 
         FIG. 2  is a partially broken-away perspective view showing detail of the locking system and cart of the encircled area  2  of  FIG. 1 ; 
         FIG. 2A  is an enlarged detail view of the locking system of  FIG. 2 ; 
         FIG. 3  is an exploded perspective view of the locking system of  FIG. 2A ; 
         FIG. 4A  is a cross-sectional view of the locking system of  FIG. 2A , taken along line  4 A— 4 A, and illustrating the locking system in a locked state; 
         FIG. 4B  is a cross-sectional view of the locking system of  FIG. 4A , taken along line  4 B— 4 B; 
         FIG. 5  is a cross-sectional view, similar to  FIG. 4A , depicting the locking system manipulated to an unlocked state using a key; 
         FIG. 6A  is a cross-sectional view similar to  FIG. 4A , illustrating the locking system in an electronically unlocked state; 
         FIG. 6B  is a cross-sectional view of the lock system of  FIG. 6A , taken along line  6 B— 6 B; 
         FIG. 7A  is a cross-sectional view similar to  FIG. 4A , illustrating the locking system in a manually locked condition after being unlocked electronically; and 
         FIG. 7B  is a cross-sectional view of the lock system of  FIG. 7A , taken along line  7 B— 7 B. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1–2 , a medical cart  10  including a locking system  12  incorporating features of the present invention is shown. The cart  10  has an enclosure  14  which houses a number of drawers  16 , mounted on slides  18  and supported by a chassis or frame structure  20  within the enclosure  14 . A series of locking tabs  22  are secured within the enclosure  14  and are supported by the frame  20  for movement to lock all of the drawers  16  in a closed position. The drawers  16  may be used, for example, to store medicines for individual patients and the cart  10  is provided with casters  24  to enable the cart  10  to be easily moved within a facility so that the cart  10  may be taken to individual patient rooms for administration of the medicines. 
     Referring now to  FIGS. 2 ,  2 A and  3 , the locking system  12  of the present invention includes a lock mechanism having an actuating member  32  which may be selectively engaged with the locking tabs  22  of the cart  10  to thereby move the locking tabs  22  to secure or release the drawers  16  of the cart  10 . In the exemplary embodiment shown, the actuating member  32  is provided with a cam surface  34  which engages the locking tab  22 . The actuating member  32  has a locked position wherein the cam surface  34  engages the locking tab  22  and moves the locking tab  22  to capture tines  36  of the drawers  16  with latches  38  coupled to the locking tab  22 . The actuating member  32  may be selectively moved to an unlocked position wherein the cam surface  34  disengages the drawer locking tab  22  to release the tines  36  from the latches  38  and thereby unlock the drawers  16 . 
     With continued reference to  FIGS. 2 and 3 , and referring further to  FIGS. 4A–4B , the actuating member  32  further includes a connecting arm  40  which is coupled to a manually actuated lock mechanism of the locking system. The manually actuated lock mechanism includes a lock core  42  which is slidably received in a first channel  44  in a lock housing  46  formed by first and second housing halves  46   a,    46   b  secured by fasteners  47 , whereby movement of the lock core  42  within the lock housing  46  causes the actuating member  32  to move between the locked position (e.g.  FIG. 4A ) and unlocked position (e.g.  FIG. 5 ). A spring  48  disposed between the interior of the housing  46  and the lock core  42 , biases the lock core  42  in a direction toward the unlocked position of the actuating member  32 . A carriage bolt  50  installed through corresponding slots  52   a,    52   b  formed in first and second halves  46   a,    46   b  of the housing  46  extends through holes  54 ,  56  formed in the lock core  42  and the connecting arm  40 , respectively, to thereby couple the actuating member  32  to the lock core  42 . The elongated slots  52   a,    52   b  formed in the housing  46  also establish limits of travel for the actuating member  32  between the locked and unlocked positions. 
     The lock core  42  includes a selectively retractable lock pin  60  protruding from an upper surface of the lock core  42 . The lock pin  60  may be selectively caused to retract within the lock core  42  by manual manipulation of a key  62  inserted into a keyway  64  of the lock core  42 . In the first, locked position of the lock core  42 , the lock pin  60  engages a spring-biased lock catch  66  which protrudes into the first channel  44  (when not urged from the first channel  44  by the electronically actuated lock mechanism described below) to engage the pin  60  and thereby retain the lock core  42  in the first position as best depicted in  FIGS. 7A and 7B . The lock catch  66  is biased to protrude into the first channel  44  by a second spring  68  disposed between the lock catch  66  and a retainer plate  70  secured to the housing  46  by a fastener  72 . When the key  62  is inserted into the keyway  64  and manipulated to retract the lock pin  60 , the lock core  42  is biased to the second, unlocked position by the first spring  48  disposed between the lock core  42  and an end wall of the housing  46 . As best illustrated with reference to  FIGS. 4A and 5 , the first spring  48  is positioned over the connecting arm  40  and, because the actuating member  32  is coupled to the lock core  42 , the first spring  48  also biases the actuating member  32  toward the unlocked position ( FIGS. 7A–7B ) when the lock core  42  has been released from the lock catch  66 . 
     The locking system  12  further includes an electronically actuated lock mechanism configured to move the actuating member  32  between the locked and unlocked position without the need for a key  62  to manually operate the lock core  42 . In the exemplary embodiment shown, the electronically actuated lock mechanism includes a release member  80  slidably disposed within a second channel  82  formed between the first and second housing halves  46   a,    46   b.  The release member  80  includes a release catch  84  having a first surface  86  configured to engage the lock pin  60  to thereby prevent the lock core  42  from moving in a direction toward the second, unlocked position relative to the release member  80 . A second surface  88  of the release catch  84  is inclined with respect to the lock pin  60  so that the lock pin  60  is caused to retract within the lock core  42  as the release member  80  is moved in a direction toward the second position of the lock core  42  to engage the second surface  88  of the release catch  84  with the lock pin  60 . 
     The electronically actuated lock mechanism further includes a drive motor  90  operatively coupled t 6  the release member  80  and actuable to move the release member  80  in a direction toward the second position of the lock core  42  or, alternatively, in a direction toward the first position of the lock core  42 . The drive motor  90  has an output shaft  92  coupled by coupling members  93   a,    93   b  to a lead screw  94  that extends through the second channel  82  in the housing  46  to engage the release member  80 . Drive motor  90  is secured to the cart frame  20  by a mounting plate  89  and fasteners  91   a,    91   b.  The release member  80  is formed with internal threads  96  which engage the lead screw  94  whereby rotation of the output shaft  92  in a first direction causes the release member  80  to move toward the second position of the lock core  42 . Likewise, rotation of the output shaft  92  in an opposite direction causes the release member  80  to move in a direction toward the first position of the lock core  42 . 
     The drive motor  90  is coupled by wires  98  to a power supply (not shown) and a control circuit  100  (see  FIG. 2 ) of the medical cart  10 . When a user enters an appropriate access code via a keypad  102 , or other input device coupled to the control circuit  100 , the control circuit  100  energizes the drive motor  90  to move the release member  80  and thereby unlock or lock the cart  10 , as described more fully below. In the embodiment show in  FIG. 2 , control circuit  100  is supported within the enclosure  14  by a support bracket  106  secured to frame  20 . A protective cover  108  may be provided on support bracket  108  to protect the control circuit  100  from moving components of the cart  10 . 
     A secondary control circuit  101  may be provided to receive input from the keypad  102 , or other user input device, and to communicate with control circuit  100  when a valid access code has been entered. While the user input device has been shown and described herein as a keypad  102  for entering an access code, it will be recognized that the input device may alternatively be a barcode scanner, a magnetic stripe reader, a device for verifying a bio-identification metric, or any other device suitable for receiving an input parameter and limiting access to the cart  10 . 
     Referring now to  FIGS. 4A ,  4 B,  5 ,  6 A,  6 B and  7 A– 7 B, operation of the locking system  12  to selectively lock and unlock the drawers  16  of the medical cart  10  will now be described.  FIGS. 4A–4B  depict a locked condition of the cart  10  wherein the lock core  42  is in the first, locked position and the actuating member  32  is in the first position such that the cam surface  34  of the actuating member  32  engages the drawer tab  22  to cause the latch  38  on the drawer tab  22  to engage the tines  36  on the drawers  16  and thereby prevent opening of the drawers  16 . 
     In the exemplary embodiment depicted in  FIGS. 4A–4B , the release member  80  is shown at its greatest extent of travel in the direction toward the first position of the lock core  42  such that the release catch  84  of the release member  80  engages the lock pin  60  and prevents movement of the lock core  42  toward the second, unlocked position. When the release member  80  is in this position, the release member  80  also displaces the spring-biased lock catch  66  and prevents the lock catch  66  from protruding into the first channel  44  of the housing  46 . Accordingly, the lock catch  66  normally protrudes into the first channel  44  of the housing  46  to engage the lock pin  60  when the lock core  42  is in the first position, as best depicted in  FIGS. 7A–7B , but is displaced by the release member  80  to disengage the lock pin  60  and thereby permit the electronically actuated lock mechanism to move the lock core  42  between the first and second positions when the electronically actuated lock mechanism is actuated to lock and unlock the drawers  16  of the cart  10 , as will be described more fully below. 
     To manually unlock the drawers  16  of the cart  10 , the access key  62  is inserted into the keyway  64  of the lock core  42  and is actuated by rotating the key  62  to retract the lock pin  60  within the lock core  42  as best depicted with reference to  FIGS. 4A and 5 . After the lock pin  60  is retracted into the lock core  42 , the lock core  42  is biased by the first spring  48  toward the second, unlocked position as depicted in  FIG. 5 . As the lock core  42  moves toward the second position, the actuating member  32  moves toward the unlocked position whereby the cam surface  34  disengages the drawer tab  22  and the drawer tab  22  moves in an upward direction so that the latch  38  releases the drawer tine  36  thereby permitting the drawers  16  of the cart  10  to be freely opened. 
     When it is desired to subsequently lock the drawers  16  of the cart  10  after manually unlocking them, the lock core  42  may be moved from the second position to the first position by manually pushing the lock core  42  into the housing  46  to thereby engage the lock pin  60  with the release catch  84  in the first, locked position. The lock pin  60  is displaced by the sloped, second surface  88  of the release catch  84  as the lock core  42  is moved from the second position to the first position. After the lock pin  60  has passed the first surface  86  of the release catch  84 , the lock pin  60  snaps back into the extended position whereby the first surface  86  of the release catch  84  engages the lock pin  60  and prevents movement of the lock core  42  from the first position toward the second position. 
     Alternatively, the locking system  12  of the cart  10  may be operated by utilizing the electronically actuated lock mechanism. Operation of the locking system  12  in this mode may be advantageous, for example, when the key  62  for the locking system  12  is unavailable. With reference to  FIGS. 4A–4B  and  6 A– 6 B, the drawers  16  of the cart  10  may be unlocked when a user enters an appropriate access code into the keypad  102 , or other user input device, as described above. After the appropriate access code has been entered, and when the release member  80  is in the position depicted in  FIGS. 4A–4B , the drive motor  90  is energized to cause the release member  80  to move in a direction toward the second position of the lock core  42 . Because the release member  80  displaces the lock catch  66 , as described above, the lock core  42  is biased by the first spring  48  to move with the release member  80  toward the second, unlocked position, as depicted in  FIGS. 6A–6B . 
     When it is desired to re-lock the drawers  16  of the cart  10 , or when the control circuit  100  otherwise determines that the drawers  16  of the cart  10  should be locked, the drive motor  90  is energized to rotate the lead screw  94  in a direction to move the release member  80  in a direction toward the first position of the lock core  42  whereby the release catch  84  engaged with the lock pin  60  causes the lock core  42  to move from the second, unlocked position to the first, locked position, as depicted in  FIGS. 4A–4B . 
     Alternatively, after the locking system  12  has been unlocked electronically, and is in the position illustrated in  FIG. 6A–6B , the locking system  12  may be manually locked by manual displacement of the lock core  42  from the second position toward the first position. When the locking system  12  is operated in this manner to manually lock the cart  10  after being unlocked electronically, the lock pin  60  engages the lock catch  66  in the first position as depicted in  FIGS. 7A–7B  while the release member  80  remains in a position extended in a direction toward the second position of the lock core  42 . The lock pin  60  engages a sloped surface  104  on the lock catch  66  to thereby cause the lock catch  66  to retract from the first channel  48  and allow the lock core  42  to be moved to the first position. When the lock core  42  is in the first position, the lock catch  66  is biased back into the first channel  48  of the housing  46  by the second spring  68  to thereby engage the lock pin  60  and prevent movement of the lock core  42  from the first position toward the second position. 
     When the medical cart  10  has been locked manually after having been unlocked electronically, as described above and depicted in  FIGS. 7A–7B , and it is subsequently desired to unlock the cart  10  electronically, it will be recognized that the control circuit  100  must first energize the drive motor  90  to cause the release member  80  to move in a direction toward the first, locked position of the lock core  42  to thereby disengage the lock catch  66 . In an exemplary embodiment, control circuit  100  will automatically cause the release member  80  to return to the first, locked position of the lock core  42  when the cart is manually locked after having been unlocked electronically. Subsequently, the control circuit  100  is energized the drive motor  90  to cause the release member  80  to move in a direction toward the second, unlocked position of the lock core  42 , as described above with respect to  FIGS. 4A–4B  and  6 A– 6 B. 
     The locking system  12  of the present invention may therefore be operated to lock and unlock the drawers  16  of the medical cart  10  either electronically or manually as described above. Advantageously, the locking system  12  of the present invention permits users to selectively lock or unlock the drawers  16  of the cart  10  manually or electronically, regardless of whether the drawers  16  have been previously locked or unlocked either manually or electronically. To facilitate the proper operation of the cart  10 , the locking system  12  further includes sensors configured to detect the various conditions of the locking system  12 . In the exemplary embodiment shown, the locking system  12  includes a first sensor  110  to detect whether the lock core  42  is in the first, locked position. In this embodiment, the first sensor  110  comprises a switch that is actuated by the carriage bolt  50  that couples the actuating member  32  to the lock core  42  and which extends through the slots  52   a,    52   b  formed in the first and second housing halves  46   a,    46   b.    
     In another embodiment, the locking system  12  further includes second and third sensors  112 ,  114  configured to determine when the release member  80  has reached desired limits of travel in both the direction toward the first position of the lock core  42  and in the direction toward the second position of the lock core  42 . In the exemplary embodiment shown, the second and third sensors  112 ,  114  comprise optical sensors positioned within the housing  46  to detect when the release member  80  has reached the respective limits of travel. The first, second, and third sensors  110 ,  112 ,  114  are mounted to a circuit board  116  and communicate with the control circuit  100 . A conductive member  118  is attached to the housing  46  and is operatively coupled to the cart frame  20 , such as by contact with a fastener  120 , to dissipate static electricity from the housing  46  and thereby protect sensors  110 ,  112 ,  114  and circuit board  116 . 
     The sensors  110 ,  112 ,  114  provide signals to the control circuit  100  which are used by the control circuit  100  to determine when the drive motor  90  should be de-energized to stop the release member  80  at the respective limits of travel, and to determine when the release member  80  must be moved toward the first position to disengage the lock catch  66  and thereby unlock the system  12  electronically subsequent to manual locking of the system  12 , as described above. 
     While the present invention has been illustrated by the description of an embodiment thereof, and while the embodiment has been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and method and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope or spirit of the general inventive concept.