VHS videocassette security device
BACKGROUND OF THE INVENTION 
     VHS Video has been the standard media for recording/viewing video for the past ten years. Inherent to the design of this videocassette is a means to prevent accidental erasure or damage due to recording over existing recorded material. This device is a plastic tab that upon removal, leaves a recess at the rear of the videocassette. When this tab is removed sensors indicate this condition and prevent use of the videocassette recorder (VCR) record mode. However, application of a piece of adhesive tape over the recess, where the tab was located allows normal use of the videocassette. Also, this means of protection does not secure the videocassette against unauthorized viewing of the video tapes contents. 
     Generally, most video cassettes have a blind hole for the purpose of locating the videocassette during playing/recording. Generally, this same blind hole has opposing radial openings and at about mid depth of the hole. Intersecting this hole at the bottom of the videocassette is a track to prevent improper loading of the videocassette. A mating post built into the video recorder/player must pass uninhibited through this track for proper loading of the videocassette. 
     It is the principle object of this invention to provide a tamper resistant device that is of simple and inexpensive construction for use with standard VHS videocassette designs, is simple to use, and which is highly effective to ensure the safety of the contents of a videocassette tape from both damage and unauthorized viewing. 
    
    
     The above and other objects and advantages of this invention will be more readily apparent from the following descriptions read in conjunction with the accompanying drawings in which: 
     FIG. 1 is a perspective view, with a cut away view, of a standard VHS videocassette into which is fitted a security device of the type embodying this invention. 
     FIG. 1a is an enlarged perspective view detailing the cut away view in FIG. 1. 
     FIG. 2 is an elevational view of the body of said device. 
     FIG. 3 is an elevational cross section view of the body of said device. 
     FIG. 4 is an exploded view of said device. 
     FIG. 5 is a cross section elevational view of the blind hole of a videocassette in which is shown an elevational view of said device in the locked position. 
     FIG. 6 is a cross section elevational view of the blind hole of a videocassette showing the radial undercuts and in which is shown an cross section elevational view of the assembly of said device in the locked position. 
     FIG. 6A thru D are cross section elevational views of said device shown in a cross sectional view of the blind hole of a videocassette, in four operative positions of the pawl. 
    
    
     FIGS. 1 and 1a show a security device  8  which is fitted into the blind hole  10  of a conventional VHS videocassette tape  9 , of the type being used extensively in commerce at the present time. As shown in FIGS. 2 and 3, the device consists of a cylindrical body  13  having an inside surface and an outside surface and further having a hole  14 , said inside surface of said body further defining an opening  17  contiguous with said hole at the top for the fitting of a key. The circumference of said hole  14  is larger at the top than at the bottom of said hole. The larger hole serves to guide the working end of the key  15  into the smaller hole  16  and is also used during removal of the device  8 . Said inside surface defines a radial opening  17 , forms a bottom wall  18  and extends radially through the center of said body forming a partial side wall  19  adjacent to the bottom wall and continues above the side wall through the opposite side of the body. A diameter  20  is bored through the body  13  perpendicular to its axis and perpendicular to the larger radial opening  17  for the fitting of a cross pin  22  (FIGS. 2-4). 
     As depicted in FIG. 4, a pawl  21  is moveably disposed within the radial opening  17  and is moveably attached to the inside surface thru hole  26  by a cross pin  22  ; such that, the primary locking surface  23  protrudes beyond the body  13  and a secondary locking surface  24  radially opposite the primary locking surface  23  is positioned inside the cylinder by an equal amount. The pawl is biased to a predetermined position by a spring  28  having two ends. The spring is contained at one end by a notch  27  in the body of the pawl and at the opposite end by the bottom wall  18  of said inside surface  17 . Referring to FIG. 6, the pawl position is set by the top of the inside surface  29  and the cross pin hole  20  location. Furthermore, the pawl  21  is allowed to rotate between its rest or primary lock position and the secondary lock position of the pawl where the under side 30  of the secondary locking surface  24  strikes the top surface  31  of the cylinder&#39;s side wall  19  (FIG. 6b). 
     When the assembly is placed into the blind hole  10  of a standard videocassette, while maintaining the pawl  21  parallel to the length of the videocassette  9 , the pawl  21  is rotated from its rest position by the caming action of pawl surface  25  against the wall of the blind hole 10  toward its neutral position (FIG. 6a). In this position, both primary locking surface  23  and secondary  24  locking surface are each substantially flush with the cylindrical body diameter  13  allowing full insertion of the device, without use of the key, into the blind hole  10 . 
     Prior to bottoming the device  8 , the primary locking surface  23  engages in the radial undercut  32a  of the videocassette thus returning to its rest postion and thereby locking the device  8  in the videocassette  9  until the neutral position is achieved, allowing the device  8  to be extracted from the videocassette  9  (FIGS. 5 and 6). When fully bottomed the top surface  33  (having the larger circumference hole) of the device  8 , is located flush with or slightly above the bottom surface of the videocassette  11  so as to substantially block the videocassette loading guide track  38  (used to prevent improper loading) located on the bottom surface  11 , and adjacent to the front surface  12  of a standard VHS videocassette tape (FIG. 1). Thus loading of the videocassette  9  is prevented until the device  8  is removed. 
     Furthermore, the secondary locking surface  24  provides a simple, inexpensive, and yet highly effective means of resisting tampering to accomplish removal of the device  8 . If the pawl  21  is depressed beyond the neutral position of the primary locking surface (FIG. 6c) in a direction opposite to that caused by the spring  28  force, the secondary lock surface  24  engages the videocassette undercut opposite the primary lock  23  causing the pawl  21  to interfere at the under cut surface  32b  thereby preventing removal of the device  8  (FIG. 6b). Removal can only be accomplished by insertion of a specially designed key. The key  34  is made of a compressible material and is designed to both set the pawl  21  in the neutral position and engage the larger circumference hole key hole  14  so as to maintain a frictional force allowing the device  8  to be extracted from the videocassette  9 . The pawl&#39;s  21  neutral position is achieved by bottoming the under side  35  of the key head against the top surface  33  of the body  13 . The pawl  21  is urged to rotate from its biased position under the force of the key tip  15  as the key contacts the pawl&#39;s top surface  36  (directly under the key tip  15 ) as shown in FIG. 6c. 
     Once the neutral position of the pawl is achieved using the key, removal of the device  8  is accomplished by means of applying a force to the key  34  so as to lift the device  8  out of the blind hole  10 . Frictional loading between the sides of the key  37  bearing on the larger circumference hole  14  overcome the load of the spring  28  (FIG. 6d) thus allowing removal of said device. Due to the location of the device  8  in the videocassette, direction of bias of the spring, and the restrictive diameter of the small circumference hole; removal by any means other than the key  34  is substantially inhibited, as upward movement of any tampering device returns the pawl  21  to the primary lock postion. 
     Dimensions from the under side  35  of the key head to the key tip surface  15  and from the cross pin hole  20  to the pawl top surface, 36  achieve the predetermined neutral position. These dimensions are designed to be varied proportionally to provide unique key settings rather than a one key fits all condition. 
     A VHS videocassette locked in this manner is rendered unusable until the device is removed. The contents of the videocassette tape cannot be viewed or altered by conventional means as the videocassette cannot be loaded into a standard videocassette player/recorder. Thus the tape contents are secured from unauthorized use. This device significantly improves upon the present state of the art used to prevent accidental tape erasures. Additional security can provided by adapting a keyed lock to this system.