Abstract:
A system and apparatus for controlling keys or other objects is provided. The key can only be removed when an access control key identifying the individual who is removing the key is inserted. The access control key cannot be removed until the key is returned.

Description:
TECHNICAL FIELD 
   The invention relates to the field of devices for storing keys and managing and controlling access to the keys. 
   BACKGROUND 
   In various situations such as vehicle dealerships, vehicle rentals, equipment rentals, vehicle repair shops and the like, numerous keys are being held at any given time. It is important to control access to such keys so that only authorized individuals may remove the keys and also to be able to identify which individual has possession of a particular key at any given time. 
   A number of systems have been patented in the area of devices for controlling access to stored keys in which a master key is used to release the subject key or article. U.S. Pat. No. 4,472,952 Hollowell, Jr. discloses a system for the management of the issuance and return of articles such as keys, tools and the like. It uses a master unlocking key to engage a geared locking bar which then frees the locking key attached to the article and locks the master key in the device. The master key is released when the locking key is re-inserted into the device and turned to cause a gear to move the geared locking bar to the original position. U.S. Pat. No. 4,641,509 Batchelor et al. discloses a system for retaining and controlling keys in which a universal key turns a lug which engages a notch in the subject key to retain it or release it when the universal key is returned to its original position. In this system the subject keys must be notched by a grinder in order for the system to work. U.S. Pat. No. 5,505,066 Baucom discloses a device for alternately locking a selected one of a pair of keys and releasing the other key for removal from the device. It uses a visitor key having a geared end which engages a geared slider and moves the slider when the visitor key is rotated to alternately release the home key and secure the visitor key or secure the home key and release the visitor key. A system of cams and pins prevents the visitor key from being removed when the home key is removed and vice versa. 
   U.S. Pat. No. 5,372,021 Smith discloses a key control device which uses a primary key and lock and a secondary key and lock. The cylinders of the two locks are interconnected by a tie rod or gears such that insertion of one of the two keys frees the second key and retains the first key, and vice versa. U.S. Pat. No. 5,878,613 Tabacchi et al. discloses a key control device which uses an access key and lock and a stored key and lock. Rotation of the keys rotate cams which engage with a lid whereby only one key can be removed at any time and removal of one key prevents removal of the other key. 
   SUMMARY OF INVENTION 
   The invention provides a key control apparatus comprising: a plurality of key control units; a plurality of key holding elements each adapted to have a key attached to it; a plurality of access control elements; each control unit having a passage for alternately receiving a unique one of said key holding units and a passage for receiving any one of said access control elements; whereby said key control element can be removed by inserting any of one of the access control elements into said passage but said access control element can only be removed when said unique corresponding key holding element is inserted into said control unit. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
     In drawings which illustrate a preferred embodiment of the invention 
       FIG. 1  is a front view of a key control and storage cabinet according to the invention; 
       FIG. 2  is a detail view of a portion of the key control and storage cabinet shown in  FIG. 1 ; 
       FIG. 3  is a perspective cross-sectional view of a key control unit according to the invention; 
       FIG. 4  is a side cut-away view of a key control unit according to the invention; 
       FIG. 5  is a rear perspective cut-away view of a key control unit according to the invention; 
       FIG. 6  is a perspective view of a key holding element according to the invention; 
       FIG. 7  is a rear perspective of a key holding element according to the invention; 
       FIG. 8  is an elevation view a master key element according to the invention; and 
       FIG. 9  is a front perspective view of the faceplate of a control unit according to the invention. 
   

   DESCRIPTION 
   Throughout the following description, specific details are set forth in order to provide a more thorough understanding of the invention. However, the invention may be practiced without these particulars. In other instances, well known elements have not been shown or described in detail to avoid unnecessarily obscuring the invention. Accordingly, the specification and drawings are to be regarded in an illustrative, rather than a restrictive, sense. 
   With reference to  FIGS. 1 and 2 , a key control storage cabinet  10  has an array of control units  11 , each having a unique numerical identifier  41  on front panel  40  and an opening  42  for receiving a correspondingly numbered key holding element  12 , to which can be attached a key ring  16  having a key  14  and an identification tag  15  ( FIG. 2 ). In the example shown, the control units  11  are numbered consecutively 1 to 40. Associated with each key holding element-receiving opening  42  is an access control key receiving opening  18  ( FIG. 2 ) for receiving an access control key  19 . When not in use the access control keys can be stored in an array of openings  13  marked with employee names. 
   As shown in  FIGS. 2 and 3 , each control unit  11  is mounted in an elongated extruded aluminum frame  45  and has a front panel  40  having numerical identifier  41 , and openings  18  and  42  which receive respectively shank  34  of access control key  19  and the shank  20  of key holder  12  (see  FIG. 4 ). Opening  42  has an array of holes  43  around it, as shown also around opening  18  ( FIG. 9 ), only selected ones of which holes extend completely through the face plate  40  in order to match the unique configuration of pins  30  on one of the key holders  12 . 
   With reference to  FIGS. 4 and 5 , openings  18 ,  42  communicate with cylindrical channels  46 ,  48  in housing  47  of control unit  11 . Channels  46 ,  48  each has a spring  50  and a sliding cylinder  52  located therein. Springs  50  are maintained in place by posts  51 . Each control unit  11  has a central vertical passage  60  which holds two freely-moving ball bearings  54 ,  56 . Ball bearings  54 ,  56  are sized to fit in hemispherical cut-outs  24 ,  38  of key holder  12  and access control key  19  respectively, as described further below. A bar or plate  62  extends across channels  46 ,  48  to block the passage of sliding cylinders  52  but permit the passage of the half-round ends  25 ,  39  of shanks  34  and  20  of key holder  12  and access control key  19  respectively. 
   As shown in  FIGS. 6 and 7 , each key holder  12  comprises a cylindrical shank  20  and cylindrical head  22  having a diameter larger than shank  20  and a ring  21  for attaching a key ring. Shank  20  has a hemispherical cut-out  24  on the upper surface thereof adjacent end  25 . The end  25  of shank  20  furthest from head  22  is half-round, being cut away to form a flat surface  23 . Head  22  has a flat number-bearing surface  26  and a rear surface  28  from which project four pins  30 . 
   Similarly, as shown in  FIGS. 4 and 5 , each access control key  19  comprises a cylindrical shank  34  and cylindrical head  36  having a diameter larger than shank  34 . Shank  34  has a hemispherical cut-out  38  adjacent end  39 . The end  39  of shank  34  farthest from head  36  is half-round, being cut away to form a flat surface  35 . Head  36  has a flat identification-bearing surface  40 , to display a unique number corresponding to an individual, and a rear surface  44  but unlike key holder  12  there are no pins projecting from surface  44 . 
   As shown in  FIG. 8  a master access key  80  can also be provided. It is generally the same in features and dimensions as the access control key  19 . It comprises a cylindrical shank  84  and cylindrical head  86  having a diameter larger than shank  84 . The end  89  of shank  84  furthest from head  86  is half-round, being cut away to form a flat surface  85 . Shank  84  has a cut-out  88  adjacent end  89  but unlike cut-out  38  in access control key  19 , it is cut-out right to the end of end  89  so tat the master key is not retained by ball bearing  54 . Head  86  has a flat identification-bearing surface  82  to identify it as a master key, and a rear surface  83  but again unlike key holder  12  there are no pins projecting from surface  83 . 
   In operation, a key holding element  12  is removed from cabinet  10  using a master access key  80 , and key  14  is attached to the key holding element  12  along with an identification tag  15  which identifies the customer, type of vehicle, license no. etc. The key holding element  12  is then returned to cabinet  10 , and then cannot be removed due to spring  50  biasing sliding cylinder  52  in position whereby ball bearing  56  extends into the hemispherical cut-out  24  of key holder  12 . Each key holder  12  can only be received in one unique control element  11  due to the configuration of pins  30  and the half-round end  25  of shank  20 . When a uniquely numbered access control key  19  is inserted into opening  42  it compresses spring  50  and ball bearing  54  is pushed into hemispherical cut-out  38 , and ball bearing  56  is forced out of cut-out  24  as key holder  12  is pushed out of channel  48  by spring  50 , and can then be removed from control unit  11 . Access control key  19  cannot now be removed from control unit  11  due to the biasing of spring  50  causing sliding cylinder  52  to hold ball bearings  54 ,  56  in place. Access control key  19  can only be removed similarly when the unique key holder  12  corresponding to that control unit  11  is replaced. By putting a unique identifier such as a number or initials on face  40  a manager can identify which individual has possession of the key which has been removed from a particular control unit  11 . Even if a second access key  19  is inserted into opening  42  while an access key  19  is in opening  18 , the latter cannot be removed since the cut-away  38  on the second access key will not be in position to interact with ball bearing  56  when the half-round end is appropriately oriented to by-pass plate  62 . Thus the manager will know which individual employee has control of the key in question. 
   As an alternate procedure, the manager may use the master key  80  first thing in the day to remove all key holders  12  from the cabinet and then replace them as keys are left by customers during the day. 
   In order to facilitate manufacture of the unique pin  30  configurations, face plate  40  can be injection molded having the array of 12 holes partially penetrating the face plate but for a thin wall of plastic which can then be removed by hand in the desired locations to match the configurations of pins  30  on key holders  12 . 100 unique pin configurations can be provided using 4 pins, by varying the position of 2 pins in one of 5 holes on one half of the circumference to provide the first digit from 0 to 9 and the second digit from 0 to 9 is then provided by varying the position of the other 2 pins in one of 5 holes on the other half of the circumference. 
   As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.