Locking device for computer disk drives and the like
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to locking devices used for securing computer equipment and cassette tape decks, and more particularly, to a device for preventing unauthorized use of computer floppy disk drives or cassette tape decks. 
     2. Description of the Prior Art 
     The invention is an improvement on devices such as U.S. Pat. No. 4,856,304 by Jay S. Derman, U.S. Pat. No. 4,640,106 by Jay S. Derman and U.S. Pat. No. 4,131,001 by Raymond J. Gotto. U.S. Pat. No. 4,131,001 utilizes a cassette-shaped part for insertion in the cassette chamber opening. The rotation of a lock cylinder moves projecting arms and locking members against the inside chamber surfaces preventing removal of the locking device. U.S. Pat. No. 4,856,304 utilizes a transverse plastic block and a &#34;T&#34; shaped tongue piece of stainless steel. The tongue piece is inserted in a horizontal slot in the transverse block and the rearward projecting member of the assembly is inserted in the cassette chamber opening. When pulled by hand, a projecting ridge on the tongue piece bears against the inside edge of the chamber opening. A cylinder lock is rotated to engage a slot cut in the tongue piece, preventing the device from being removed. 
     U.S. Pat. No. 4,640,106 uses an assembly to cover the cassette door opening and a &#34;U&#34; shaped body bolt together with a threaded rod for insertion in the cassette chamber. A locking element located on the threaded rod is rotated in position by a cylinder lock to prevent removal of the device. 
     U.S. Pat. No. 4,856,304 is considered the most simple in construction. However, the tongue piece remains somewhat complex. It is also limited in its adjustment stops, using either slots for a cam lock or holes for a padlock. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a device for preventing the unauthorized use of a computer disk drive, a cassette tape deck, CD player or similar equipment. The invention improves on U.S. Pat. No. 4,856,304 in that the locking mechanism utilizes a &#34;showcase&#34; type lock, rather than the described &#34;T&#34; shaped member tongue piece and cam lock or padlock to hold the block assembly in place in the disk drive, cassette tape deck, CD player or similar equipment. This use of a &#34;showcase&#34; type locking mechanism provides an increased number of adjustment stops for the user, while simplifying the device further in its construction, reducing its costs. 
     The principal object of the present invention is to provide a device that presents the user with an improved lock adjustment capability, when used to block access to computer disk drives and the like, as well as providing a simpler, lower cost device construction. 
     Further objects and advantages of the present invention will become apparent from a study of the following portion off the specification, the claims and the attached drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front perspective view of the preferred embodiment of the present invention, installed in a computer disk drive and locked in place; 
     FIG. 2 is a front perspective view of the preferred embodiment of the present invention, assembled and ready for use; 
     FIG. 3 is a partial cross-section view of a computer disk drive wall at its slot and part of the locking device inserted in the slot, particularly showing how the locking element hooks on to the inside surface of the drive wall, including a view of the rearward member filling the slot height; 
     FIG. 4 is a side elevation view of the present invention; 
     FIG. 5 is a bottom plan view of the device, particularly showing the serrated edge of the locking element which is located in its guide slot at the center of the block; 
     FIG. 6 is a front perspective view of an alternate embodiment of the present invention, particularly showing how the cylinder lock may be separately used apart from the block; 
     FIG. 7 is a side elevation view of the alternate embodiment of the device; and 
     FIG. 8 is a bottom plan view of the alternate embodiment of the device, particularly showing the locking element which is located in its guide slot at the center of the block and the relationship of the cylinder lock that can slide along the locking element. 
    
    
     DESCRIPTION OF THE PREFERRED AND ALTERNATE EMBODIMENTS 
     Referring particularly to the drawings, there is shown in FIGS. 1 and 2, a preferred embodiment of the present invention. In FIG. 1, a partial view of a computer 1, particularly showing its floppy disk drive 2 and drive slot 3, illustrates the use of the invention. The transverse block 4 of the device is shown inserted in the drive slot 3 with its locking element 5 pulled forward tightly, so that the transverse block 4 bearing surfaces are pushed hard against the wall of the disk drive 2, covering access to the drive slot 3. FIG. 2 shows a perspective of the device ready for insertion in a disk drive, tape deck or other similar equipment such as a CD player. Also shown is a partial view of the rearward bearing member 8, against which the locking element 5 bears and is located. 
     Referring to FIG. 3, the device is held tight to the disk drive wall 2 by a bend in the locking element 5, shown in its pulled forward position, hard against the inside surface 12 of the disk drive wall. This same hooking arrangement works just as well when the device is used with a cassette tape deck or CD player. The only difference in the device used for each equipment is its dimensions. Referring to FIGS. 4 and 5, the block width &#34;A&#34; for a cassette tape deck lock device would be about 2.5 inches and the rearward member 8 thickness &#34;B&#34; about 0.40 inches. This compares with a block width of about 1.3 inches and a rearward member thickness of about 0.15 inches for the computer disk drive locking device. The larger width for the cassette tape deck device is required so that the device rearward member 8 may completely fill the tape deck opening, acting like a cassette while preventing side play of device and slot. 
     In FIGS. 4 and 5, the cylinder lock 7 is shown located perpendicular to the axis of the locking element 5 and the transverse block 4. The transverse block 4 is made of a rigid plastic while the locking element 5 is made of 0.050 inch thick stainless steel or equivalent strength material. 
     The locking element 5 represents an improvement over the equivalent function performed by a &#34;T&#34; shaped tongue piece in an earlier invention (U.S. Pat. No. 4,856,304). Its action together with the vertical cylinder lock 7, is based on the well known &#34;showcase&#34; type lock, possessing compactness, simplicity and relatively fine adjustment. The locking element 5 achieves these attributes by having a fine sawtooth edge 6 cut in one edge of the element 5, with the sawtooth having a typical width, peak to valley, of 0.10 inches. This allows adjustment of the locking element in 0.10 inch or less steps. The element also has a narrow width typically of approximately 0.375 inches; a thickness of only approximately 0.050 inches and a length of approximately 3 inches. One end of the locking element 5 is bent at a right angle to the plane of the element for a length of approximately 0.25 inches, forming a &#34;hook&#34; to enable hooking onto the inside surface 12 of the disk drive wall as shown in FIG. 3. The locking element 5 is used in conjunction with a cylinder lock 7 which is placed normal to the plane of the locking element 5. In this embodiment, the cylinder lock 7, when a key is inserted in it and rotated, projects a rounded pin which acts against the sawtooth edge 6 of the locking element 5, allowing the element to be pulled and ratcheted forward only. 
     Manufacture of the transverse block 4 can be in one or two parts: an upper section including the rearward member 8 and a lower section 9. A circular cutout 10 is 5 made in top surface of the lower section 9 to accommodate the bottom portion of the cylinder lock 7. A hole is cut vertically in the center of the upper section; the hole diameter being sized to accommodate the cylinder lock 7 casing. Also, a groove 11 is cut in the upper section as shown in FIG. 5, to provide a guide location for the locking element 5. The transverse block 4 is assembled after the cylinder lock 7 is first inserted in place; the lower section 9 of the block being either glued or fastened by screws to the upper section. 
     Referring now to FIGS. 6, 7 and 8, there are shown views of an alternate embodiment of the instant invention. In this embodiment, the block 13 is one piece of rigid plastic, formed in a disk shape and including a rearward projecting member 16. The disk-shaped block 13 serves the same purpose as the transverse block 4 of the preferred embodiment, in blocking access to computer disk drives when the rearward member 16 is inserted in the drive slot. A slot is cut in the center of the block 13, continuing as a groove 17 in the surface of the rearward projecting member 16. The purpose of the slot and groove is to accommodate and guide the locking element 15 as shown in FIGS. 7 and 8. 
     The locking element 15 is exactly the same as that used in the preferred embodiment, except that its length is shorter by one inch because the thickness of the disk-shaped block 13 is also about one inch less than the block in the preferred embodiment. It operates in the same manner. The major difference in this embodiment, is that the cylinder lock 14 is not located in and held by the block, but rather slides along the locking element 15 as required. In use, the block rearward projecting member 16 is inserted in the disk drive slot and the locking element 15 is pulled forward so that the bent portion of the locking element 15 hooks against the inner wall of the disk drive. The cylinder lock 14 is then slid forward until it abuts hard against the front surface of the disk-shaped block 13, effectively holding the device locked in place. It should be noted, that the cylinder lock 14 is specially shaped with one side of its casing long axis flattened in order to be able to abut the front surface of the block 13 properly. 
     Referring to FIG. 8, the width &#34;A&#34; of the rearward member 16 is dependent on the width and height of the disk drive slot in which it is intended to be inserted. A typical width would be 1.3 inches for current makes of disk drives. It could also be as much as 5 inches wide, depending on the device application. 
     Finally, as depicted in FIGS. 6, 7 and 8, the alternate embodiment of the locking device represents what is considered to be the utmost simplification of a locking device for computer disk drives and the like. It is simple to use and simple to manufacture. As such, it is believed to be a worthy improvement on the prior art. 
     Various changes and modifications may be made in the construction and mode of operation of the locking device described above. These changes, which are in accordance with the spirit of this invention, come within the scope of the appended claims and are embraced thereby.