Abstract:
A lock mechanism for manually or automatically fixing a slide bar in either of two positions. A lock body has a key barrel adapted to rotate a lock cam in a first rotational direction. A latch is biased in a closed position, the latch being adapted to move to an open position when the lock cam is rotated in the first rotational direction. A slide bar is fixable in a locked position and an unlocked position, wherein the slide bar is biased in the unlocked position. A knob slider is adapted to move the slide bar into the locked position such that the latch moves to the closed position and engages a notch of the slide bar to fix the slide bar in the locked position. A servo motor is adapted to rotate a servo cam in a second rotational direction to move the slide bar into the locked position, and is adapted to rotate the lock cam in the first rotational direction to move the slide bar into the unlocked position. The key barrel is adapted to rotate in the first rotational direction to move the slide bar into the unlocked position. The lock mechanism can be made smaller, more compact, less expensive, have fewer parts, and be easier to manufacture.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a lock mechanism assembly having automatic and manual locking procedures for locking drawers in a cabinet, and more generally to an improved lock mechanism for fixing a slide bar in either of two positions. 
     2. Description of the Related Art 
     There are many examples of manual or automatic means for locking drawers in a cabinet. One type of cabinet for which locking drawers can be especially important is a medical supply cart. A medical supply cart commonly contains medical equipment, instruments, and supplies that are necessary for treating patients in the hospital. Security of such items can be particularly important to prevent unauthorized dispensing or use of such items. 
     A supply cart generally includes a housing having a plurality of drawers, shelves, and/or compartments for storing the medical equipment and supplies. The housing is typically supported by a plurality of wheels or casters so that it may be moved from its place of storage to the location of the patient. To provide security of the items contained therein, supply carts typically have a security latch mechanism for simultaneously securing all compartments of the cart in a sealed condition. 
     One example of a drawer closing and latching mechanism is disclosed in U.S. Pat. No. 6,511,138 to Gardner et al. As discussed in that patent, drawers which are slightly ajar are grasped by the latching mechanism, pulled fully closed, and locked shut. A latch finger engages a catch connected to the drawer and pulls the drawer closed. The finger is actuated by a crankshaft which, as it rotates, first lowers the latch finger to capture the catch, and then retracts the latch finger and with it the captured drawer. The crankshaft rotates to a position where any pull forces on the finger are nearly in line with the axis of the crankshaft and have little tendency to cause reverse rotation. The crankshaft is then retained in this position, effectively locking the drawer closed. 
     While prior art systems such as that disclosed in the Gardner patent are generally good for their intended purposes, the current state of the art of such conventional lock mechanisms would benefit from improvements in a number of respects. For example, there is a need for an improved lock mechanism that is smaller and simpler, with fewer parts, that is less expensive, and the operation of which is highly reliable. 
     SUMMARY OF THE INVENTION 
     The present invention provides an improved lock mechanism for fixing a lock block or slide bar in either of two positions. The slide bar may be, in turn, coupled to a lock mechanism that locks and unlocks drawers or other compartments of a supply cart. The lock mechanism according to the present invention can be smaller, more compact, less expensive, and have fewer parts. Therefore, the lock mechanism is highly reliable in operation. The lock mechanism according to the present invention can also be simpler to manufacture. One reason for this is that the lock mechanism can be comprised of less complex pieces that are, for example, injection molded. 
     In accordance with one aspect, the lock mechanism of the present invention includes a housing, a slide bar mounted in the housing for translational movement between a first position and a second position, a first biasing spring for exerting a bias force against the slide bar toward the second position, and a slide bar actuator mounted in the housing for urging the slide bar toward the first position against the force exerted by the first biasing spring. A latch is also mounted in the housing and is movable between a first position in which it holds the slide bar in the first position when moved thereto, and a second position in which the latch releases the slide bar permitting it to move to the second position thereof under the force exerted by said first biasing spring. 
     A second biasing spring exerts a force on the latch and a cam is rotatably mounted in the housing and has a lobe engagable with the latch for, upon rotation in one direction, urging said latch to its second position thereby releasing said slide bar to move to the second position. 
     According to a further aspect of the present invention, there is provided a lock mechanism for manually or automatically fixing a slide bar in either of two positions. A latch is biased to a closed position, to hold the slide bar in one position, namely, a locked position, the latch being adapted to move to an open position when a lock cam is rotated by a key barrel in a first rotational direction to release the slide bar. The slide bar is fixable in the locked position, but biased toward the unlocked position. A knob slider, which is connected to the slide bar through a lost motion coupling, is adapted to move the slide bar manually into the locked position such that the latch moves to the closed position and engages a notch of the slide bar to fix the slide bar in the locked position. A servo motor is provided and may be optionally controlled to be operable to rotate a servo cam in the one rotational direction also to move the slide bar into the locked position, and is also further operable to rotate the servo cam in an opposite direction to move the latch to the open position. 
     The latch may be biased toward the closed position by a spring. The slide bar may be biased toward the unlocked position also by a spring. The lock mechanism may further comprise a plurality of positioning screws to define a range in which the slide bar can slide, opposing ends of the range corresponding to the locked position and the unlocked position, respectively. The lock mechanism may further comprise a knob adapted to actuate the knob slider. The servo motor may be controlled by a controller. 
     According to another aspect of the present invention, there is provided a lock mechanism having a locked mode and an unlocked mode. A lock block is adapted to slide between a first position and a second position, the lock block being biased to the second position. A lock block actuator is operable to slide the lock block from the second position to the first position. A servo motor is adapted to rotate a servo cam in a first direction also to move the lock block from the second position to the first position. In the unlocked mode the lock block is in the second position and in the locked mode the lock block is in the first position. 
     The lock mechanism may further comprise a latch that is biased toward a closed position, the latch being adapted to move to an open position when the servo cam is rotated in a second direction. When the knob slider moves the lock block from the second position to the first position, the latch moves to the closed position and engages a notch in the lock block to fix the lock block in the first position. 
     A better understanding of these and other aspects, features, and advantages of the invention may be had by reference to the drawings and to the accompanying description, in which preferred embodiments of the invention are illustrated and described. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of a lock mechanism for fixing a slide bar in either of two positions according to one embodiment of the present invention. 
         FIG. 2  is a back view of the lock mechanism shown in  FIG. 1 . 
         FIG. 3  is a left side view of the lock mechanism shown in  FIG. 1 . 
         FIG. 4  is a right side view of the lock mechanism shown in  FIG. 1 . 
         FIG. 5  is a top view of the lock mechanism shown in  FIG. 1 . 
         FIG. 6  is a bottom view of the lock mechanism shown in  FIG. 1 . 
         FIG. 7  is a perspective view of the lock mechanism shown in  FIG. 1  taken from the right and above. 
         FIG. 8  is a left perspective view of the lock mechanism shown in  FIG. 1  taken from the left and above. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An exemplary embodiment of the present invention will be discussed with reference to the accompanying figures. According to this embodiment of the present invention, a lock mechanism has a lock block or slide bar which can be fixed in either of two positions: a first lowermost (locked) position and a second uppermost (unlocked) position. It is of course to be understood that the directional terms used in this description, such as “lowermost” and “uppermost,” are merely for explanatory purposes relative to the views shown in the drawings, and are not meant to limit the orientation of the lock mechanism of the present invention in any way. The present invention according to this embodiment has both automatic and manual procedures for fixing the slide bar in the locked position. 
       FIG. 1  and  FIG. 7  are respectively a front view and a perspective view of a lock mechanism  10  according to the exemplary embodiment of the present invention. As can be seen there, lock mechanism  10  has a front plate  12 , preferably made of metal, on which is mounted a mechanical lock body  14  having a barrel  16  for receiving a key (not shown). A knob  18  is attached to and moves together with a knob slider  20 , the knob  18  having a post  18   a  that projects through and is slidable in a front plate slot  22  at least during a locking procedure described below. A plurality of self-clinching nuts  24  are adapted to receive screws for securing the lock mechanism  10  to an apparatus that is to be locked, such as a medical supply cart. A lock tab connector  26  is provided to couple the lock mechanism to a corresponding lock mechanism (not shown) in the cart to operate it to lock and unlock, for example, drawers in the cart. 
       FIG. 2  and  FIG. 8  are respectively a back view and a perspective view of the lock mechanism  10  in accordance with the preferred embodiment. As can be seen further there, the lock mechanism  10  also has a back plate  28 , preferably made of metal, which is secured to the front plate  12  via a plurality of screws  30 . The front plate  12  and back plate  28  may be considered together to define a housing. A lock block or slide bar  32 , mounted for translational movement on the back plate  28  as described in greater detail below, is coupled to the knob slider  20 , as illustrated in more detail in the left side and right side views shown in  FIGS. 3 and 4 , respectively. The connector  26  is secured to the slide bar  32  such that its movement, as described below, controls locking and unlocking of the cart. The slide bar  32  is coupled to the knob slider  20  through a lost motion coupling such that the slide bar  32  can be pulled down by the knob slider  20  (via the knob  18 ) in a manual locking procedure described further below. However, if the knob slider  20  is pulled up (via the knob  18 ), the slide bar  32  does not follow. More specifically, a finger  32   b  projects from the slide bar  32  through a slot  35  (see  FIGS. 3 and 8 ) of the back plate  28  and is engaged with a recessed channel  32   c  of the knob slider  20 . When the knob slider  20  is pulled down (via the knob  18 ), the top of the recessed channel forces the engaged finger  32   b  downwardly. When the knob slider  20  is pulled up, the upper edge of the slot  22  in the front plate  12  engages the knob post  18   a  to stop the knob  18 , and, therefore, stops the knob slider  20  before the bottom of the recessed channel of the knob slider  20  would begin to force the engaged finger  32   b  upwardly. 
     The slide bar  32  also has two elongated slots  29 ,  31  for receiving positioning screws  33 ,  34  respectively. The positioning screws  33 ,  34  are secured to the back plate  28  and operate, along with the slots  29 ,  31 , to mount the slide bar to the back plate and to define upper and lower limits of the range in which the slide bar  32  can move. The positioning screws  33 ,  34  preferably carry washers, as shown, to ease the sliding movement of the slide bar. 
     During the locking/unlocking procedures described herein, the slide bar  32  is movable between two positions, i.e., a first lowermost (locked) position and a second uppermost (unlocked) position. A tension spring  36 , the ends  36   a  and  36   b  of which are respectively connected to the back plate  28 , and slide bar  32  through the lock bar connector  26 , biases the slide bar  32  in the upward direction toward the second position. 
     In the locked position, as shown for example in the perspective view of  FIG. 8 , the slide bar  32  is fixed in the lowermost position by a latch  38 , which is mounted for pivoted, inward and outward movement about a pivot pin  41 . The latch  38  engages an upper notch  32   a  in the slide bar  32  when the slide bar  32  is in the locked position. The latch  38 , therefore, fixes the slide bar  32  in the lowermost (locked) position by preventing upward movement of the slide bar  32  against the biasing of the spring  36 . A second tension spring  40 , having ends  40   a  and  40   b  respectively connected to the back plate  28  and the latch  38 , biases the latch  38  inwardly so that the latch  38  will engage the notch  32   a  when the slide bar is moved to the locked position. 
     As described above, when locked the slide bar  32  is fixed in the lowermost position. When unlocked, the slide bar  32  is fixed in the uppermost position. The unlocking procedure is as follows. 
     If the slide bar  32  is in the locked position, a user can effect the unlocking procedure by inserting a key into the barrel  16  of the lock body  14  and turning the key counterclockwise (when viewed from the front of the lock mechanism  10 ), for example. Thus turning the key causes a lock cam  42  connected for rotation with the lock barrel mechanism also to turn counterclockwise. The lock cam has a lobe  42   a  that engages the latch  38  and forces it to move outwardly away from engagement with the upper notch of the slide bar  32 , i.e., causes the latch  38  to move against the bias of the spring  40 . As this action occurs, the slide bar  32  is released from its lowermost position and is pulled to the uppermost (unlocked) position by the spring  36 , where it remains fixed until the next locking action. The lock cam  42  may also be formed with a stop  42   b  that blocks over-rotation of the cam. 
     Manual and automatic locking procedures according to the present invention are next described. In order to manually lock the lock mechanism  10 , a user may pull down on the knob  18 . In so doing, the knob slider  20 , which is connected to both the knob  18  and the slide bar  32  as described above, forces the slide bar  32  downwardly. When the slide bar  32  is forced to the lowermost position, the latch  38  is pulled inwardly by the spring  40  and engages the notch  32   a  in the slide bar  32  as described above. This engagement prevents upward movement of the slide bar  32  until a subsequent unlocking procedure takes place and, thus, fixes the slide bar  32  in the locked position. 
     In addition, as shown in  FIGS. 3 and 7 , the lock cam optionally may be formed with a second lobe  42   b  that engages the top of the slide bar when the barrel  16  of the lock body  14  is turned clockwise through operation of the key. This action will then also advance the slide bar to the locked position. 
     Automatic locking of the lock mechanism in accordance with the invention may be provided by a servo actuator. More particularly, a servo cam  44  (see, e.g.,  FIG. 7 ) is mounted for rotation coaxially with the lock cam  42 . When the slide bar  32  is in the uppermost (unlocked) position, the servo cam  44  may optionally be controlled to be rotated clockwise as seen from the front of the lock mechanism  10 . The cam is formed with a lobe  44   a  that engages and thereby forces the top of the slide bar  32  downwardly through interaction between the two, fixing the slide bar  32  to the lowermost (locked) position. The servo cam  44  may then be returned to its initial position so that it does not interfere with the unlocking procedure (e.g., by keeping the slide bar  32  fixed in the locked position), and so that it is ready for the next locking procedure. 
     The servo cam  44  is controlled and driven by a servo motor  46 , which is secured through an opening in the back plate  28  by way of a plurality of through-holes and screws  47 . The servo motor  46  is electrically connected to an electronic controller (not shown) that may be located apart from the lock mechanism  10 . A limit switch  48 , having terminals  48   a, b, c , is also connected to the electronic controller. When the lock mechanism  10  is locked, the bottom of the slide bar  32  contacts and trips an actuator or lever  48   d  to close the limit switch  48 . A signal will thereby be sent to the controller to indicate that the slide bar  32  is in the lowermost position, and, therefore, that the lock mechanism  10  is locked. At this position, the servo motor is stopped to prevent further advance of the slide bar. 
     When the lock mechanism  10  is unlocked, the bottom of the slide bar  32  moves upwardly as described earlier and thereby permits the switch actuator  48   d  to open with the limit switch  48 . 
     A control program causes the controller of the servo motor  46  to control the servo cam  44  with respect to various locking schemes according to the “autolock” mode of the present invention. For example, the servo motor  46  can be controlled to rotate the servo cam  44  to move the slide bar  32  into the locked position in response to a code input by an operator through a keypad (not shown), or after the lock mechanism  10  has been unlocked for a predetermined time period. The servo motor  46  can still further be controlled to rotate the servo cam  44  to move the slide bar  32  into the locked position at a set time of day. Suitable control schemes are known and available, for example, in commercial cart locking systems available form Lionville Systems, Inc. and identified as LockAlert and LockAlert VI. Thus, as is apparent, the servo motor  46  can be programmed to effect various autolocking schemes. 
     The control program in the controller of the servo motor  46  can also direct the servo motor  46  to rotate the servo cam  44  to effect the unlocking procedure. Specifically, the servo motor  46  can be controlled to rotate the servo cam  44  clockwise. The cam includes a second lobe  44   b  which then forces the latch  38  to move away from engagement with the notch  32   a  of the slide bar  32 , i.e., causes the latch  38  to move against the biasing of the spring  40 . As this action occurs, the slide bar  32  is released from its lowermost position and is pulled to the uppermost (unlocked) position by the spring  36 . The controller of the servo motor  46  can be programmed to effect the unlocking procedure, for example, in response to a code input by an operator through a keypad, at a set time, or after the lock mechanism  10  has been locked for a predetermined time period. Again such programming schemes are known or are within the skill of the art. 
     The controller of the present invention or any part(s) or function(s) thereof may be implemented using hardware and software and may be implemented in one or more computer systems or other processing systems. It is noted that the servo motor  46  may be controlled by one or more modules contained in the controller. The modules can operate in accordance with software control programs and operating routines stored in an associated memory or memories. The modules and their sub-modules can write and/or read information to/from the memory or memories, and in this way, can perform operations in accordance with the present invention. The modules may be implemented using hardcoded computational modules or other types of circuitry, or a combination of software and circuitry modules. Software routines for performing the modules can, in one embodiment, be stored as instructions in a memory and can be executed by a processor of a control module. 
     The software may be stored in a computer program product, a computer program medium, or a computer-readable medium, and loaded into a computer system using a removable storage drive, a hard drive, or a communications interface. The control logic (software), when executed by a processor, causes the processor to perform the automated functions of the invention as described herein. 
     In this document, the terms “computer program medium” and “computer usable medium” are used to refer generally to media such as a removable storage drive, a hard disk installed in a hard disk drive, and signals. Also, “computer-readable medium” is used to refer generally to media such as a storage drive, CD, hard drive or other tangible objects that can store a program. These computer program products provide software to the system. 
     It will be appreciated from the description provided above and the accompanying drawings that the front and back plates, slide bar, latch and lock and servo cams are all relatively thin or narrow in their minor dimensions or extents, and that in their respective major dimensions or extents extend in substantially parallel planes. Therefore, the lock mechanism in accordance with the present invention is very compact. 
     In addition, the invention lock mechanism has few moving parts. Therefore, it is highly reliable and can be made efficiently and inexpensively. 
     While the present invention has been designed with a cabinet or medical supply cart in mind, the present invention is not limited to such, but could be used for locking other types of devices, in commercial or non-commercial settings. 
     One of ordinary skill in the art will realize that modifications and variations, including but not limited to those discussed above, are possible within the spirit and scope of the present invention. The invention is intended to be limited in scope only by the accompanying claims, which should be accorded the broadest interpretation so as to encompass all such modifications, equivalent structures and functions.