Abstract:
An improved locking mechanism and method for securing drawers and cabinet doors is disclosed which allows the drawers and cabinet doors to be only partially opened until the locking mechanism is unlocked. When the drawer or cabinet door is closed, the hidden locking mechanism of the present invention is entirely concealed from view behind the drawer or cabinet door. The locking mechanism of the present invention allows the drawer or cabinet door to be opened sufficiently to expose the locking mechanism, but effectively prevents the drawer or cabinet door from being more than slightly opened until the locking mechanism is unlocked. When the locking mechanism is unlocked, the drawer or cabinet door may then be fully opened.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates generally to locking mechanisms and methods of locking drawers and cabinet doors, and more particularly to an improved locking mechanism and a method of installing such a locking mechanism to prevent a drawer or a cabinet door from being fully opened when locked, the locking mechanism being concealed from view until the drawer or cabinet door is opened slightly and effectively preventing the drawer or cabinet door from being fully opened until the locking mechanism is unlocked. 
     A wide variety of locking mechanisms for use with drawers or cabinet doors have been developed for use in preventing access to the contents of such drawers or cabinets. There have been two prevalent reasons for using such locking mechanisms: first, to secure the contents of a drawer or cabinet; and second, to prevent children from gaining access to dangerous or fragile contents of a drawer or cabinet. 
     While the first reason has always required the use of a positive locking mechanism, the second reason has resulted in a wide variety of mechanical latches which are designed to be opened by adults while preventing at least small children from opening them. Unfortunately, all too often, small children are able to easily open such mechanical latches, while adults are able to open them only with considerable difficulty. Accordingly, the present invention is concerned with a locking mechanism rather than with a latching mechanism. 
     As might well be expected, the art is replete with examples of such locking mechanisms. Four examples of locking mechanisms illustrated in the art will be mentioned briefly. The first, which is illustrated in U.S. Pat. No. 2,094,895, to Karpenske et al., shows a locking mechanism for securing drawers in a desk. A key lock contained in the top center drawer of the desk actuates a mechanism which locks all of the drawers in the desk. In a further aspect, Karpenske et al. teach the use of the locking mechanism to secure handles in a recessed position within the drawers until the drawers are unlocked, at which time the handles are released so that they may be used to pull the drawers out. 
     While the Karpenske et al. reference is quite clever in its construction, it has the considerable drawback that it requires a highly complex mechanism which must be built into both the frame of the desk and the drawers. This mechanism is simply not readily adaptable for use with either previously installed drawers or with cabinet doors. 
     A second type of locking mechanism for use with drawers is illustrated in U.S. Pat. No. 3,909,090, to Breckner et al. The Breckner et al. reference teaches an interlocking drawer locking mechanism for use with a multi-drawer filing cabinet to prevent more than one drawer from being opened at a time. This mechanism is useful to prevent the weight of the contents of the drawers from tipping the filing cabinet over if more than one drawer is opened at the same time. 
     Unfortunately, like the Karpenske et al. reference discussed above, the Breckner et al. reference requires a mechanism that is built in and is not readily adaptable to installation at a later time. In addition, it actually does not lock any of the drawers in a filing cabinet; rather, Breckner et al. allows all of the drawers to be opened, but just one at a time. 
     A third type of locking mechanism is illustrated by U.S. Pat. No. 2,886,392, to Stegmaler. The Stegmaler reference also shows a filing cabinet locking system, with a combination lock mounted on one drawer being used to lock all of the drawers in the filing cabinet. When the combination lock is unlocked, the drawer on which the combination lock is mounted may be slid partly out to unlock all of the other drawers. Just like the other references previously mentioned, the Stegmaler reference is built into the filing cabinet and is not particularly adaptable for use with existing drawers or cabinet doors. 
     Finally, one additional reference will be mentioned by way of example to illustrate the complexity of much of the previously known art. U.S. Pat. No. 4,460,222, to Larking, teaches a drawer apparatus with a relatively simple locking mechanism. The Larking device is a drawer for use in banks and similar secure applications, with a simple mechanism used to prevent it from being opened from the outside once it has been locked from the inside. Even the simple mechanism disclosed in Larking must be built in, and is simply not adaptable for use on unsecured drawers without a great deal of difficulty. 
     It is accordingly the primary objective of the present invention that it provide a locking mechanism which may be installed to releasably secure a single drawer or a cabinet door. It is a further principal objective of the present invention that the locking mechanism be completely invisible until and unless the drawer or the cabinet door is partially opened. As such, it is a related objective of the present invention that it allow the drawer or the cabinet door on which it is installed to be opened sufficiently to allow access to the locking mechanism so that it may be unlocked, but that it effectively deny access to the contents of the drawer or the cabinet unless and until it is unlocked. 
     It is a further objective of the hidden locking mechanism of the present invention that it be quick and easy to lock and unlock. It is yet a further objective of the hidden locking mechanism of the present invention that it be sufficiently flexible to allow its use on a variety of different size and configuration drawers and cabinet doors without requiring a wide variety of different configurations to be provided, and that it be installable using only simple hand tools. It is a still further objective of the hidden locking mechanism of the present invention that it be configurable as either a key lock or a combination lock, and that it categorically prevent children from unlocking the locking mechanism unless they have the key or the combination. 
     The hidden locking mechanism of the present invention must be of a construction which is both durable and long lasting, and it should also require little or no maintenance to be provided by the user throughout its operating lifetime. In order to enhance the market appeal of the hidden locking mechanism of the present invention, it should also be of inexpensive construction to thereby afford it the broadest possible market. Finally, it is also an objective that all of the aforesaid advantages and objectives of the hidden locking mechanism of the present invention be achieved without incurring any substantial relative disadvantage. 
     SUMMARY OF THE INVENTION 
     The disadvantages and limitations of the background art discussed above are overcome by the present invention. With this invention, a two component hidden locking mechanism is presented for installation to releasably secure a furniture storage compartment such as a drawer or a cabinet. The two components of the hidden locking mechanism of the present invention are a retention mechanism and a bolt which may be releasably engaged by the retention mechanism. One of the components of the hidden locking mechanism is mounted onto the moveable member of the furniture storage compartment (a drawer or a cabinet door), and the other component of the hidden locking mechanism is mounted onto the fixed member of the furniture storage compartment (the frame into which the drawer installed or onto which the cabinet door is mounted). Both the retention mechanism and the bolt are mounted so that they are hidden when the drawer or cabinet door is closed. 
     The proximal end of the bolt is mounted onto a mounting plate, with the distal end of the bolt extending outwardly from the mounting plate. The retention mechanism has an aperture located therein for receiving the distal end of the bolt therein. The distal end of the bolt has a projection extending therefrom (or, alternatively, a notch located therein) which may be releasably engaged by a tumbler contained within the retention mechanism. 
     When the retention mechanism is locked, the tumbler will engage the distal end of the bolt and prevent it from being withdrawn from the retention mechanism. When the retention mechanism is unlocked, the tumbler will be disengaged from the distal end of the bolt and will allow it to be withdrawn from the retention mechanism. The retention mechanism may use either a combination lock or a key lock to control the operation of the tumbler, with either type of lock being well known in the art. 
     When the hidden locking mechanism of the present invention is used with a drawer, in a first embodiment the retention mechanism may be mounted on the inside of the front panel of the drawer. The retention mechanism will thus be completely hidden when the drawer is closed. In this embodiment, the bolt is mounted onto the frame of the drawer so that the bolt will move into the aperture in the retention mechanism, where its distal end may be engaged by the tumbler of the retention mechanism. 
     The bolt and the retention mechanism are configured to allow sufficient movement of the distal end of the bolt between first and second positions within the retention mechanism to allow the drawer to be opened sufficiently to expose the lock of the retention mechanism. Thus, once the bolt is engaged in the retention mechanism, the drawer will be allowed to move between its fully closed position and a position in which it is opened only sufficiently to expose the lock of the retention mechanism. When the lock is unlocked, the bolt will be released from the retention mechanism, allowing the drawer to be fully opened. 
     In a second embodiment of the hidden locking mechanism of the present invention used with a drawer, the retention mechanism may be mounted under the top side of the frame of the drawer. Again, the retention mechanism will be completely hidden when the drawer is closed. In this embodiment, the bolt is mounted on the inside of the front panel of the drawer so that as the drawer is closed, the bolt will move into the aperture in the retention mechanism, where its distal end will be engaged by the tumbler of the retention mechanism. 
     If desired, the bolt may be mounted on its mounting plate so that it may pivot between a deployed position and a folded position. In the deployed position, the bolt will be engaged by the retention mechanism when the drawer is closed, allowing the hidden locking mechanism of the present invention to lock the drawer. In the folded position, the bolt will lie close adjacent its mounting plate or the surface on which its mounting plate is mounted, allowing the drawer to be closed without being locked. 
     The hidden locking mechanism of the present invention may also be used with a hinged cabinet door. Preferably, in this application the bolt is curved between its proximal and distal ends to allow for the pivoting motion of the cabinet door. This curve in the bolt will allow it to smoothly move into the aperture contained in the retention mechanism. Alternately, the pivoting bolt described above may be used with application of the hidden locking mechanism of the present invention with cabinet doors. 
     In a first embodiment, the retention mechanism may be mounted in the frame of a cabinet door, underneath the top of the frame and adjacent the side opposite the hinges. In this embodiment, the bolt is mounted on the inside of the cabinet door, near the top and the side opposite the hinges. When the cabinet door is closed, the bolt will move into the aperture in the retention mechanism, where its distal end will be engaged by the tumbler of the retention mechanism. The bolt and the retention mechanism will allow sufficient movement of the distal end of the bolt within the retention mechanism to allow the cabinet door to be opened sufficiently to expose the lock of the retention mechanism. 
     In a second embodiment, the retention mechanism may be mounted on the inside of the cabinet door, in a convenient position on the side opposite the hinges. In this embodiment, the bolt is mounted in the frame of a cabinet door, adjacent the side opposite the hinges and in a position to be engaged by the retention mechanism when the cabinet door is closed. 
     It may therefore be seen that the present invention teaches a locking mechanism which may be installed to releasably secure a single drawer or a cabinet door. The hidden locking mechanism of the present invention is completely invisible unless and until the drawer or the cabinet door is partially opened. As such, it allows the drawer or the cabinet door on which it is installed to be opened sufficiently to allow access to the locking mechanism so that it may be unlocked, but it effectively denies access to the contents of the drawer or the cabinet unless and until it is unlocked. 
     The hidden locking mechanism of the present invention is quick and easy to lock and unlock. It is sufficiently flexible to allow its use on a variety of different size and configuration drawers and cabinet doors without requiring a wide variety of different configurations to be provided, and it is installable using only simple hand tools. The hidden locking mechanism of the present invention is configurable as either a key lock or a combination lock, and it categorically prevents children from unlocking the locking mechanism unless they have the key or the combination. 
     The hidden locking mechanism of the present invention is of a construction which is both durable and long lasting, and which will require little or no maintenance to be provided by the user throughout its operating lifetime. The hidden locking mechanism of the present invention is also of relatively inexpensive construction to enhance its market appeal and to thereby afford it the broadest possible market. Finally, all of the aforesaid advantages and objectives of the hidden locking mechanism of the present invention are achieved without incurring any substantial relative disadvantage. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     These and other advantages of the present invention are best understood with reference to the drawings, in which: 
     FIG. 1 is a top plan view of a retention mechanism constructed according to the teachings of the present invention, showing a combination lock; 
     FIG. 2 is a front side view of the retention mechanism illustrated in FIG. 1, showing two mounting apertures and an aperture into which an engaging bolt may be inserted, with a tumbler visible within this aperture; 
     FIG. 3 is a back side view of the retention mechanism illustrated in FIGS. 1 and 2; 
     FIG. 4 is a partially cutaway view of the retention mechanism illustrated in FIGS. 1 through 3, better showing the tumbler located within the retention mechanism; 
     FIG. 5 is a top plan view of a bolt assembly having a mounting plate located at one end thereof and a projection located at the opposite end thereof for engagement with the tumbler contained within the retention mechanism illustrated in FIG. 4; 
     FIG. 6 is a front side view of the bolt assembly illustrated in FIG. 5, showing two apertures contained in the mounting plate; 
     FIG. 7 is a back side view of the bolt assembly illustrated in FIGS. 5 and 6; 
     FIG. 8 is an isometric view of a drawer mounted in a drawer frame, with the retention mechanism illustrated in FIGS. 1 through 4 mounted inside the front panel of the drawer and the bolt assembly illustrated in FIGS. 5 through 8 mounted in the top of the drawer frame to be engaged by the retention mechanism when the drawer is closed; 
     FIG. 9 is a cross-sectional partial view of the drawer and the drawer frame illustrated in FIG. 8, showing the bolt assembly being engaged by the retention mechanism as the drawer is closed; 
     FIG. 10 is an isometric view of the drawer and the drawer frame illustrated in FIG. 8, but with the retention mechanism mounted in the top of the drawer frame and the bolt mounted inside the front panel of the drawer; 
     FIG. 11 is an isometric view of a retention mechanism similar to the retention mechanism illustrated in FIGS. 1 through 4, except that the retention mechanism in FIG. 11 is operable by a key; 
     FIG. 12 is a top plan view of a bolt assembly which is pivotally mounted on a mounting plate so that it may be swung to the side, with the bolt illustrated in a deployed position; 
     FIG. 13 is a top plan view of the bolt assembly illustrated in FIG. 12, with the bolt swung to the side; 
     FIG. 14 is a rear view of the bolt assembly illustrated in FIGS. 12 and 13, with the bolt swung to the side, and also showing two apertures located in the mounting plate; 
     FIG. 15 is a top plan view of a bolt assembly which is curved for use with a retention mechanism used on a hinged cabinet door; and 
     FIG. 16 is an isometric view of a cabinet door hinged on a frame, with the bolt assembly illustrated in FIG. 16 mounted on the cabinet door (which is partially cut away for clarity), and also showing a retention mechanism which is mounted at the top of the frame and which has an aperture located therein for engaging the bolt assembly as the cabinet door is closed. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The preferred embodiment of the hidden locking mechanism of the present invention comprises two components: a retention mechanism, a first embodiment of which is illustrated in FIGS. 1 through 4, and a bolt assembly, a first embodiment of which is illustrated in FIGS. 5 through 7. Referring first to FIGS. 1 through 4, a retention mechanism  30  is illustrated. The retention mechanism  30  consists of a housing member  32  having two apertures  34  and  36  extending therethrough from front to back near the left and right sides of the housing member  32  respectively as best illustrated in FIGS. 2 and 4. The two apertures  34  and  36  may be used to mount the retention mechanism  30  onto a surface (this process will be discussed below in conjunction with the description of FIGS.  8  and  9 ). 
     The retention mechanism  30  has an aperture  38  of rectangular cross section which extends therethrough from front to back intermediate the apertures  34  and  36  and nearer the aperture  36 . Located inside the housing member  32  is a tumbler  40  which slides longitudinally within a cylindrical aperture  42 . The cylindrical aperture  42  intersects the rectangular aperture  38  within the housing member  32 , and is essentially orthogonal to the rectangular aperture  38 . 
     The tumbler  40  is used to selectively engage a bolt inserted into the rectangular aperture  38 . The distal tip of the tumbler  40  which extends into the rectangular aperture  38  as best illustrated in FIG. 4 is oblique such that a bolt inserted into the rectangular aperture  38  from the rear of the housing member  32  (shown on the top side of the housing member  32  in FIG. 4) will tend to drive the tumbler  40  into the cylindrical aperture  42 , thereby allowing a bolt to be engaged in the retention mechanism  30 . 
     Located on the top side of the retention mechanism  30  is a combination lock  44  of conventional design which actuates the tumbler  40 . When the combination lock  44  is not set to the selected combination, the tumbler  40  will be biased into the position illustrated in FIG. 4, such that the distal end of the tumbler  40  extends into the rectangular aperture  38  (thereby retaining a bolt contained within the retention mechanism  30 ). When the combination lock  44  is set to the selected combination, the tumbler  40  will be withdrawn into the cylindrical aperture  42  (thereby releasing a bolt located in the rectangular aperture  38  of the retention mechanism  30  to allow the bolt to be freely removed from the retention mechanism  30 ). 
     Referring next to FIGS. 5 through 7, a bolt assembly  50  is illustrated. The bolt assembly  50  comprises a bolt member  52  which is attached at its proximal end to the bottom edge of a mounting plate  54  in an orthogonal manner, as best illustrated in FIG.  5 . The bolt member  52  has a projection  56  located at its distal end thereof which projection  56  extends outwardly from the side of the bolt member  52 . 
     It is this projection  56  which will be engaged by the tumbler  40  in the retention mechanism  30  (illustrated in FIGS. 2 through 4) when the distal end of the bolt member  52  is inserted into the rectangular aperture  38  of the retention mechanism  30  (also illustrated in FIGS.  2  through  4 ). Completing the construction of the bolt assembly  50 , there are two apertures  58  and  60  which are located in and extend through the mounting plate  54 . The apertures  58  and  60  may be used to mount the bolt assembly  50  onto a surface (this process will be discussed below in conjunction with the description of FIGS.  8  and  9 ). 
     It should be noted at this point that a variety of different constructions of the bolt member  52  could be used instead of the construction illustrated in FIGS. 5 through 7, all of which will be readily apparent to those skilled in the art. For example, instead of the projection  56 , a notch (not illustrated herein) could be located in the side of the bolt member  52  near the distal end thereof. In this alternate embodiment, the distal end of the tumbler  40  of the retention mechanism  30  (illustrated in FIGS. 2 through 4) will releasably engage this notch in the bolt assembly to secure the bolt assembly within the aperture  34  of the retention mechanism  30  (also illustrated in FIGS.  2  through  4 ). 
     Referring next to FIGS. 8 and 9, the installation of the retention mechanism  30  illustrated in FIGS. 1 through 4 and the bolt assembly  50  illustrated in FIGS. 5 through 7 into a drawer  70  and a drawer frame  72  is illustrated. The drawer  70  has a front panel  74  on which a drawer handle  76  is mounted. The retention mechanism  30  is mounted on the inside of the front panel  74  of the drawer  70  using two screws  78  and  80 , which screws  78  and  80  extend through the apertures  34  and  36 , respectively, and are then screwed into the front panel  74  of the drawer  70 . The retention mechanism  30  is located near the top of the front panel  74  of the drawer  70 . 
     The bolt assembly  50  is mounted on the top of the drawer frame  72  with the mounting plate  54  of the bolt assembly  50  mounted on the inside of the drawer frame  72  and with the bolt member  52  located under the top edge of the drawer frame  72  in a position to be engaged in the rectangular aperture  38  of the retention mechanism  30  as the drawer  70  is closed, as best illustrated in FIG.  9 . The bolt assembly  50  is mounted onto the drawer frame  72  using two screws  82  and  84  which extend through the apertures  58  and  60 , respectively, in the mounting plate  54  of the bolt assembly  50  and are then screwed into the drawer frame  72 . 
     In operation, when the drawer  70  is closed, the bolt member  52  of the bolt assembly  50  moves into the rectangular aperture  38  of the retention mechanism  30 , with the projection  56  of the bolt assembly  50  moving past the tumbler  40  of the retention mechanism  30  to lock the drawer  70 . The bolt member  52  of the bolt assembly  50  is sufficiently long to allow the drawer  70  to open sufficiently to expose the combination lock  44  of the retention mechanism  30  with the projection  56  of the bolt assembly  50  not moving past the tumbler  40  of the retention mechanism  30 . By setting the combination lock  44  to the correct combination, the tumbler  40  will be withdrawn, allowing the projection  56  of the bolt assembly  50  to be removed from the rectangular aperture  38  of the retention mechanism  30  and the drawer  70  to be fully opened. 
     In an alternate embodiment which is illustrated in FIG. 10, the bolt  50  may be mounted on the inside of the front panel  74  of the drawer  70  and the retention mechanism  30  may be mounted under the top side of the drawer frame  72 . In this embodiment, the oblique distal end of the tumbler  40  (illustrated in FIG. 4) in the retention mechanism  30  would be turned toward the front of the retention mechanism  30 . Again, the retention mechanism  30  will be completely hidden when the drawer  70  is closed. 
     In this embodiment, as the drawer  70  is closed, the bolt member  52  of the bolt assembly  50  again moves into the rectangular aperture  38  of the retention mechanism  30 , with the projection  56  of the bolt assembly  50  moving past the tumbler  40  of the retention mechanism  30  to lock the drawer  70 . The length of the bolt member  52  of the bolt assembly  50  is sufficient to allow the drawer  70  to open enough to expose the combination lock  44  of the retention mechanism  30  with the projection  56  of the bolt assembly  50  still engaged by the tumbler  40  of the retention mechanism  30 . By setting the correct combination on the combination lock  44 , the tumbler  40  will be withdrawn, freeing the projection  56  and allowing the bolt assembly  50  to be removed from the rectangular aperture  38  of the retention mechanism  30  and the drawer  70  fully opened. 
     Referring next to FIG. 11, an alternate embodiment retention mechanism  130  is illustrated which consists of a housing member  132  having two apertures  134  and  136  extending therethrough which may be used to mount the retention mechanism  130 . The retention mechanism  130  has a rectangular aperture  138  extending therethrough. Not shown in FIG. 11 is a tumbler which slides longitudinally within a cylindrical aperture located inside the housing member  132  similar to the operation of the tumbler  40  in the cylindrical aperture  42  of the retention mechanism  30  (illustrated in FIG.  4 ). The cylindrical aperture intersects and is essentially orthogonal to the rectangular aperture  138  in the housing member  132 . 
     Located on the top side of the retention mechanism  130  is a key lock  144  of conventional design which actuates the tumbler in the retention mechanism  130 . When the key lock  144  is locked, the tumbler in the retention mechanism  130  will be biased to partially obstruct the rectangular aperture  138  (thereby retaining a bolt within the retention mechanism  130 ). When the key lock  144  is unlocked, the tumbler in the retention mechanism  130  will be withdrawn into the cylindrical aperture in the retention mechanism  130  (thereby releasing a bolt located in the rectangular aperture  138  of the retention mechanism  130  to allow the bolt to be freely removed from the retention mechanism  130 ). 
     Referring now to FIGS. 12 through 14, an alternate embodiment bolt assembly  150  is illustrated. The bolt assembly  150  has a bolt member  152  which is pivotally mounted on a mounting plate  154 . The bolt member  152  has a projection  156  located at its distal end thereof which projection  156  extends outwardly from the side of the bolt member  152 . Two apertures  158  and  160  are located in and extend through the mounting plate  154  for use in mounting the bolt assembly  150 . 
     The bolt member  152  is mounted onto the mounting plate  154  using a pivot apparatus. Two parallel spaced-apart flanges  162  and  164  extend outwardly from the surface of the mounting plate  154 , with the proximal end of the bolt member  152  being located intermediate the flanges  162  and  164 . A pin  166  extends through apertures located in the flange  162 , the proximal end of the bolt member  152 , and the flange  164 . 
     Thus, the bolt member  152  may pivot with respect to the mounting plate  154  between the positions illustrated in FIGS. 12 and 13. When the bolt member  152  is in the position illustrated in FIG. 12, it extends essentially orthogonally from the mounting plate  154 ; in this position, it will engage the retention mechanism  30  (illustrated in FIG. 8) or the retention mechanism  130  (illustrated in FIG. 10) when the drawer  70  is closed. When the bolt member  152  is in the position illustrated in FIG. 13, it is folded flush with the mounting plate  154 ; in this position, it will not engage the retention mechanism  30  (illustrated in FIG. 8) or the retention mechanism  130  (illustrated in FIG. 10) when the drawer  70  is closed. 
     Referring now to both FIGS. 15 and 16, another alternate embodiment bolt assembly  250  is illustrated. The bolt assembly  250  has a curved bolt member  252  which is pivotally mounted on a mounting plate  254 . The curved bolt member  252  is also designed for use with a cabinet door  270  rather than with a drawer. The curved bolt member  252  has a projection  256  located at its distal end thereof which projection  256  extends upwardly from the side of the curved bolt member  252 . Two apertures  258  and  260  are located in and extend through the mounting plate  254  for use in mounting the bolt assembly  250 . 
     The curved bolt member  252  is mounted onto the mounting plate  254  using two parallel spaced-apart flanges  262  and  264  which extend outwardly from the surface of the mounting plate  254 , with the proximal end of the curved bolt member  252  being located intermediate the flanges  262  and  264 . A pin  266  extends through apertures located in the flange  262 , the proximal end of the curved bolt member  252 , and the flange  264 . Like the bolt member  152  in the bolt assembly  150  (illustrated in FIGS.  12  through  14 ), the curved bolt member  252  may pivot with respect to the mounting plate  254 . 
     Referring to FIG. 16, another alternate retention mechanism  230  is illustrated. The retention mechanism  230  illustrated consists of a housing member  232  having two apertures (not shown) extending therethrough from the bottom side to the top side thereof which may be used together with two screws (also not shown) to mount the retention mechanism  230  underneath the top edge of the door frame  272  in which the cabinet door  270  is mounted using hinges  274 . The retention mechanism  230  has a rectangular aperture  238  extending therethrough. 
     Not shown in FIG. 16 is a tumbler which slides longitudinally within a cylindrical aperture located inside the housing member  232  similar to the operation of the tumbler  40  in the cylindrical aperture  42  of the retention mechanism  30  (illustrated in FIG.  4 ). The cylindrical aperture is essentially orthogonal to and intersects the top portion of the rectangular aperture  238  in the housing member  232 . 
     Located on the front side of the retention mechanism  230  is a combination lock  244  which actuates the tumbler in the retention mechanism  230 . When the combination lock  244  is not set to the selected combination, the tumbler in the retention mechanism  230  will be biased to partially obstruct the rectangular aperture  238  (thereby retaining the curved bolt member  252  within the retention mechanism  230 ). When the combination lock  244  is set to the selected combination, the tumbler in the retention mechanism  230  will be withdrawn into the cylindrical aperture in the retention mechanism  230  (thereby releasing the curved bolt member  252  located in the rectangular aperture  238  of the retention mechanism  230  to allow the bolt to be freely removed from the retention mechanism  230 ). 
     It may therefore be appreciated from the above detailed description of the preferred embodiment of the present invention that it teaches a locking mechanism which may be installed to releasably secure a single drawer or a cabinet door. The hidden locking mechanism of the present invention is completely invisible unless and until the drawer or the cabinet door is partially opened. As such, it allows the drawer or the cabinet door on which it is installed to be opened sufficiently to allow access to the locking mechanism so that it may be unlocked, but it effectively denies access to the contents of the drawer or the cabinet unless and until it is unlocked. 
     The hidden locking mechanism of the present invention is quick and easy to lock and unlock. It is sufficiently flexible to allow its use on a variety of different size and configuration drawers and cabinet doors without requiring a wide variety of different configurations to be provided, and it is installable using only simple hand tools. The hidden locking mechanism of the present invention is configurable as either a key lock or a combination lock, and it categorically prevents children from unlocking the locking mechanism unless they have the key or the combination. 
     The hidden locking mechanism of the present invention is of a construction which is both durable and long lasting, and which will require little or no maintenance to be provided by the user throughout its operating lifetime. The hidden locking mechanism of the present invention is also of relatively inexpensive construction to enhance its market appeal and to thereby afford it the broadest possible market. Finally, all of the aforesaid advantages and objectives of the hidden locking mechanism of the present invention are achieved without incurring any substantial relative disadvantage. 
     Although an exemplary embodiment of the hidden locking mechanism of the present invention has been shown and described with reference to particular embodiments and applications thereof, it will be apparent to those having ordinary skill in the art that a number of changes, modifications, or alterations to the invention as described herein may be made, none of which depart from the spirit or scope of the present invention. All such changes, modifications, and alterations should therefore be seen as being within the scope of the present invention.