Abstract:
An locking device that cooperates with a predefined rectangular slot built into an external wall of the equipment to be secured. The locking device preferably includes a cylindrical body having a recessed area formed coaxially within the body. A cam assembly and a hook arm assembly are fitted within the recessed area and operably coupled to engage and release from the security slot.

Description:
TECHNICAL FIELD 
     The present invention relates generally to security devices used for preventing the theft of equipment, such as personal computers. The theft-deterrent device cooperates with a security slot in an external wall of the equipment. 
     BACKGROUND OF THE INVENTION 
     Computing has seen a dramatic shift from large, room-sized equipment accessible only to a few people to small, powerful portable computers which are economically available to the general public. The power of the new portable computers, the wide range and easy accessibility of software, and the rise in computer literacy during the last twenty years has fueled this change. 
     Another important trend is that corporations are under enormous pressure to become more efficient and profitable with significantly less staff. One solution has been to give individual employees a personal computer (PC). Originally, the only computer available was a desktop PC. However, the past five years have witnessed a tremendous shift towards easily transported and highly powerful portable computers. A direct outcome of this proliferation is that companies are storing invaluable corporate assets in the form of proprietary data on these small, easily stolen notebook computers. 
     Not surprisingly, theft of portable computers has also experienced a steep rise over the past few years, even as the price of the notebooks has declined. Frequently, the primary motivation for stealing a notebook is not the equipment itself but the data residing on it. Taking into account both the value of the hardware and the data, the 1996 losses incurred due to laptop computer theft were estimated at $805 million. 
     There are a number of methods for protecting notebooks against theft. PC Guardian (San Rafael, Calif.) and other manufacturers offer various solutions. One solution is a locking unit inserted into the diskette drive with a security cable which can be lassoed around a stationary object. Another approach uses a lock and small adhesive plate attached to the notebook, with a security cable. Another product utilizes a small security slot built into the external walls of some notebooks. Other common solutions include registering the serial number of the notebook with a central registry, or locking the notebook in a secure storage area at night. 
     All of the described solutions have problems associated with them. Use of the diskette drive is prohibited in many portables because the diskette drives oftentimes are removable. Use of a small adhesive plate is problematic because of the messiness of the installation and the adhesive plate has a tendency to catch when the portable is placed in its carrying case. The security slot solution does not always provide a snug fit and gives the perception of weakness. This solution also lacks the ability for multiple keying options. Locking up the portable in a secure storage area at night is just simply inconvenient. 
     The present invention provides a theft deterrent device which addresses these shortcomings of the prior art. The device is simple to use and it is secure and tight so as not to convey a profile of weakness. 
     SUMMARY OF THE INVENTION 
     A locking device that reduces the potential for theft of equipment such as personal computers is disclosed. The equipment to be secured has a rectangular slot with predefined dimensions built into its external wall. The locking device operably engages with the security slot to secure the equipment. 
     In the preferred embodiment, the locking device includes a cylindrical body having a recessed area formed coaxially within the body. A cam assembly and a hook arm assembly are fitted within the recessed area and operably coupled to engage and release from the security slot. 
     The body includes a latch end and a key end. The latch end has a latch opening contiguous with the recessed area and a pair of latch protrusions spaced apart on either side of the latch opening. The protrusions extend from the latch end of the body for mating engagement with the security slot. The key end has a keyway opening contiguous with the recessed area. 
     The cam assembly is fitted for axial rotation within a first portion of the recessed area proximate to the key end of the body. The cam assembly includes a keyway end and a hook arm end. The keyway end includes a predefined pattern for mating engagement with a key inserted through the keyway. The latch end includes a cam hole which is offset from the axis of the body. 
     The hook arm assembly is fitted within a second portion of the recessed area proximate to the latch end of the body. The hook arm assembly includes a pivot point centrally located on the hook arm assembly. The pivot point defines a pivot axis which is transverse to the body axis. A lever arm extends rigidly from the pivot point into the cam hole. A latch arm extends rigidly from the pivot point out the latch opening and between the protrusions. The latch arm includes a flanged lip on one end adjacent to the protrusions and adapted for mating engagement with the security slot. 
     In operation, a key is inserted through the keyway to engage the predefined pattern on the cam. Turning the key causes the cam to rotate, thereby causing the lever arm to be moved in the cam hole thereby pivoting the latch arm in an opposite direction to either engage with or release from the security slot. 
     A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description of the invention and accompanying drawings which set forth an illustrative embodiment in which the principles of the invention are utilized. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     FIG. 1 is a front perspective view of a security slot in the external wall of a piece of equipment to be protected. 
     FIG. 2 is a front perspective view of the locking device of the present invention showing the cam in an unlocked position. 
     FIG. 3 is a front perspective view of the locking device of the present invention showing the cam in a locked position. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 illustrates a conventional security slot  10  provided on the external wall  12  of equipment to be secured, for example, a personal computer. In accord with industry practice, the slot  12  is generally rectangular in shape with dimensions substantially 3 mm by 7 mm and providing a lip or flange inside the upper portion of the slot that can be latched with a suitable latching mechanism. 
     The present invention is a locking device adapted to interact with the security slot  10  to secure equipment from theft. However, those having ordinary skill will recognize that the security slot and locking device can be configured with a great variety of different dimensions according to design choice without departing from the scope of the invention. 
     Referring now to FIG. 2, the preferred embodiment of a locking device in accord with the present invention is illustrated. The locking device includes an elongate body assembly  20  that is preferably cylindrical in shape and formed with a top half  20   a  and a bottom half  20   b.  Each half of the body assembly  20  is formed to include a symmetrical and corresponding hollowed-out recess  22  that is designed to accommodate a hook arm  30  and cam  40  as described below. 
     The body assembly  20  is preferably formed of molded aluminum, but other materials may be suitable, such as stainless or hardened steel or a combination of materials. The material must be strong enough to resist moderate stress, e.g., an attempt to break the device by twisting or other means. As shown for bottom half  20   b,  the recess  22  includes a first recess portion  22   a  sized to receive the cam  40  and a second recess portion  22   b  sized to receive a pivot pin  32  which is rigidly fixed in the center of hook arm  30 . For example, the first recess portion  22   a  is a cylindrical area measuring 10.66 mm by 3.54 mm and the second recess portion  22   b  is a cylindrical area measuring 8.78 mm by 2.37 mm (diameter). A third recess portion  22   c  connects the first and second portions and measures approximately 9.16 mm by 2.43 mm by 3.51 mm. Each of the recess portions  22   a-c  is sized to loosely accommodate the hook and cam assembly as described more fully below. 
     The bottom half  20   b  of the body assembly  20  includes a pair of spaced-apart tabs or protrusions  24  rigidly protruding from the front of the body. The space  25  between the tabs  24  accommodates the hook end  31  of the hook arm  30 . The dimension occupied by the tabs  24  and space  25  is approximately 3 mm by 7 mm, i.e., they are sized to operably interact with security slot  10 . In this preferred embodiment, tabs  24  measure approximately 3 mm by 2.5 mm, and extend from the bottom half  20   b  by about 7.8 mm. Thus, space  25  is approximately 2 mm wide for receiving the hook end of the hook arm  30 . 
     The hook arm  30  is also preferably formed of molded aluminum, stainless or hardened steel or a combination of materials, with a shape roughly as shown. The hook arm  30  is generally elongate in shape with a hook end  31  extending approximately 10.16 mm from a centrally located pivot pin  32 . The hook end  31  further includes a lip or flanged portion  33  designed to latch against the inside surface of security slot  10 . 
     The pivot pin  32  is rigidly oriented transversely to the elongate direction of the hook arm  30 . The pivot pin  32  rests in the second recess portion  22   b  of the body assembly  20 . A lever arm  34  extends from the pivot pin  32  in the other direction into opening  42  in cam  40 . The lever arm  34  extends to operably rock the arm on pivot point  32  thereby moving the hook end  31  up and down to latch and unlatch, respectively, with corresponding hardware in security slot  10 . 
     The cam  40  is preferably cylindrical and measures approximately 4.94 mm by 10.41 mm (diameter) and rests in the first recess portion  22   a  of the body assembly  20 . The cam  40  includes an opening  42  in one end which is offset from the longitudinal axis of the body  20 , and a predefined key pattern  44  on the other end adapted to receive key  45  for turning the cam. 
     It can be seen in FIG. 2 that the lever arm  34  is raised by hole  42  when the cam  40  is operated to its unlocked position, thereby moving the hook portion  31  downward as shown by arrow  50  to release from the slot  10 . In FIG. 3, the cam  40  is turned 90 degrees, as shown by arrow  51 , to its locking position, where the lever arm  34  is lowered by the hole  42  and the hook portion  31  is raised as indicated by arrow  52 , thereby latching against the slot  10 . 
     It should be understood that the invention is not intended to be limited by the specifics of the above-described embodiment, but further defined by the accompanying claims.