Abstract:
An apparatus and process for the rendering unintelligible of data stored on digital and analog recording media employs a means for embossing the media and a means for driving the media to traverse a path defined by the means for embossing. In one embodiment, the means for embossing includes knurled rollers that distort the surfaces of recording media passed therebetween. In one embodiment, the means for driving the recording media through the means for embossing includes a motor and at least one drive gear operatively associated with the means for embossing. The process for rendering recorded data unintelligible includes the steps of providing a means for embossing, providing a means for driving recording media through the means for embossing, and urging recording media through the means for embossing.

Description:
RELATED APPLICATION 
     This non-provisional application, which is based upon provisional application Ser. No. 60/115,078, filed on Jan. 7, 1999, claims benefit of the filing date thereof in accordance with 35 USC 119(e). The contents of said provisional application Ser. No. 60/115,078 are herein incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention is directed generally to the field of data destruction and, more particularly, to a device that destroys the data contained on compact discs. 
     BACKGROUND OF THE INVENTION 
     Compact discs, also known as CD&#39;s, are convenient, durable storage devices that are capable of holding large amounts of data. Information on a CD is typically recorded as a series of peaks and valleys located on a reflective metallic layer disposed within the disc itself. 
     The information stored on a CD is not directly readable by the human eye; a CD player is typically used to access data stored on a given CD. CD players use lasers to “read” CD&#39;s, gathering information about the peaks and valleys on the reflective layer of a given disc. This information is processed by an associated computer which then converts the information for use. 
     Since the data stored on a compact disc is not accessible directly and must be converted before use, it is possible to prevent retrieval of the stored information without physically destroying the entire disc. Altering the disc so as to prevent access to, and conversion, of the stored data will essentially prevent retrieval of the information stored on the disc. In other words, data stored on an “unreadable” disc is often irretrievable. 
     However, due to advances in technology, the definition of what it means for a disc to be “unreadable” is evolving. It is possible, for example, to retrieve data from very small regions of a damaged compact disc. Data recorded on a CD that is otherwise unreadable with typical CD players may often still be retrieved through the use of specialized machines. As a result, simply making a disc “non-playable” does not necessarily guarantee that the information on the disc is irretrievable. It is possible, by means of special laser reading devices, to retrieve information from small particles of compact discs. Particle size has to be reduced to 0.25 mm before this retrieval method is rendered useless. 
     To achieve secure destruction of the information on a compact disc, the disc must be altered so that no technology can be employed to access any of the information previously recorded on the disc. As used in this application, the term “secure” destruction of data refers to the destruction of data in a manner that makes the data irretrievable by any means. The irretrievability requirement is of particular importance to government-agencies, especially those agencies involved with issues of national security. 
     For archival purposes, it is often desirable to retain the disc and label in readable condition, even though destruction of the underlying data is desired. In many instances, the complete destruction of a disc containing sensitive information is not desirable. In some cases, it may be appropriate to keep discs from which no data may be recovered. In situations involving national security, for example, maintaining archives of discs that have been rendered unintelligible will help establish that certain discs have actually been rendered unintelligible, rather than stolen or misplaced. Without an archive of unintelligible, yet identifiable, discs, falsified records may incorrectly indicate that discs with sensitive information have been “destroyed,” leading to possible information leaks. This type of archive requires a data destruction system that maintains the media labeling information, while rendering unintelligible the underlying data. 
     Several approaches have been explored in an attempt to achieve secure destruction of CD data. These approaches have included, among other things, the use of heat, chemical etching compounds, and standard abrasives. Unfortunately, none of these approaches has been adequate. Heating of CD&#39;s, for example, resulted in flaking of the information-containing layer. This flaking often produced loose pieces of the disc where the flake size was large enough to allow retrieval of information. Furthermore, chemical etching resulted in the production of noxious fumes which were sufficiently strong to be totally unacceptable in office environments. Abrasives, such as those used in conventional sanders, became so quickly loaded with removed debris that they were rendered useless after only a relatively-short period of use. In fact, early abrasives could not even securely destroy three CD&#39;s before the abrasive required replacement. Such a short life span is unacceptable. 
     Other approaches have used brushes or pads that contact a CD while the CD rotates. Several United States patents have been issued for these devices, as shown in U.S. Pat. Nos. 4,654,918; 4,662,025; and 4,709,437. However, none of the devices described in these patents is directed to the destruction of the information on the CD. They are merely directed to the cleaning of compact discs and, as such, do not accomplish the task of secure destruction. 
     A device for the secure destruction of CD data must irretrievably destroy the data on the disc without producing noxious fumes and must continue to operate over an extended period of time, having the capacity to destroy the information on more than three CD&#39;s. 
     Primitive abrasive systems that securely destroy the information on some types of CD&#39;s have recently been developed. Unfortunately, these abrasive systems are currently only suitable for destroying the information recording surfaces found on read-only CD&#39;s, which use aluminum recording surfaces. The abrasive systems used to destroy aluminum-surfaced discs are not satisfactory, however, for newer, recordable CD&#39;s which use gold recording surfaces. A new approach to securely destroy data stored on CD&#39;s having non-aluminum-based recording surfaces is required. 
     Thus, what is needed is a compact disc data destruction device that includes advantages of the known devices, while addressing the shortcomings they exhibit. The compact disc data destruction device should alter selected compact discs to destroy the data recorded on the disc so that recovery of the data is prevented. The device should also destroy the information on a compact disc while leaving the associated disc label in a legible format, so that the disc may be identified and accurately stored or discarded as needed. The device should also be clean to use and should not produce noxious fumes. The device should also be useable for an extended period of time, enabling destruction of data on many CD&#39;s, regardless of the type of material used for the disc information bearing surface. The device should also be economical and easy to use. 
     SUMMARY OF THE INVENTION 
     The present invention is a system for securely destroying data contained on compact discs (CD&#39;s) having gold or aluminum information bearing surfaces (IBS&#39;s). The system includes at least one pair, and typically two pairs, of rollers with each roller being rotatably mounted between rigid support plates. 
     A CD containing information to be destroyed passes between the rollers under pressure. The roller exteriors contain raised patterns that are impressed into the surface of the disc as the disc passes between the rollers. The disc surface is significantly distorted as the disc passes between the rollers. After passing between the rollers, the disc is characterized by lines of distortion that are approximately 0.25 mm apart. This spacing results in a CD from which no useful information can be retrieved. It is noted that the present invention could also be used to destroy data on a variety of recording media, including, but not limited to analog phonograph records, Digital video discs (DVD&#39;s), and laser video discs. 
     Several aspects of the present invention cooperate to produce a high level of information-destroying effectiveness. First, the patterns on the rollers may be varied greatly to avoid embossing predictable patterns on a disc. Second, the bottom-facing rollers distort the clear substrate of the disc, making it more difficult to read the data on the metal surface through the substrate. Third, the pattern on each set of rollers may be different, thereby embossing cooperative, overlaying patterns. This overlay results in a widespread distortion of the disc surfaces, with distances between embossed lines much smaller than would normally be produced by a single set of rollers. 
     Additionally, since no abrasives are used in destroying the disc, there is no need for particle collection and removal. This advantageously results in a simple device that is clean and trouble-free. The information-destroying pattern embossed on the disc beneficially does not affect the label printed on the disc. As a result, the present invention destroys data, yet preserves the original identification information used for record keeping purposes. 
     Thus, it is an objective of the present invention is to provide a device that securely destroys the data contained on CD&#39;s incorporating either aluminum or gold information bearing surfaces. 
     An additional objective of the instant invention is to provide a compact disc data destruction device that alters selected compact discs to destroy the data recorded on the disc so that recovery of the data is prevented. 
     Yet another objective of the instant invention is to provide a compact disc data destruction device that destroys the information on a compact disc while leaving the associated disc label in a legible format, so that the disc may be identified and accurately stored or discarded as needed. 
     A further objective of the instant invention is to provide a compact disc data destruction device that is clean to use and does not produce noxious fumes. 
     Still an additional objective of the instant invention is to provide a compact disc data destruction device that is useable for an extended period of time, enabling destruction of data on many CD&#39;s, if desired. 
     A still further objective of the instant invention is to provide a compact disc data destruction device that is economical and easy to use. 
     Other objects and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention. The drawings constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1A is a side elevation view of a compact disc; 
     FIG. 1B is a top plan view of a compact disc; 
     FIG. 1C is a bottom plan view of a compact disc; 
     FIG. 2 is a pictorial view of the compact disc data destruction device of the present invention; 
     FIG. 3 is a top plan view of the drive assembly of the present invention and a compact disc passing between the rollers of the present invention; 
     FIG. 4 is a partial close-up view of a compact disc showing the type of destruction accomplished with the present invention; and 
     FIG. 5 is a front view elevation of a set of rollers used in the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     It is to be understood that while a certain form of the invention is illustrated, it is not to be limited to the specific form or arrangement of parts herein described and shown. It will be apparent to those skilled in the art that various changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is shown in the drawings and described in the specification. 
     To understand the present invention, it is necessary to briefly review the construction and operation of a standard compact disc (CD). FIGS. 1A,  1 B and  1 C show, respectively, a side sectional view, a top plan view, and a bottom view of a compact disc. The CD may alternatively be referred to as a CD-ROM (Compact-Disc-Read-Only Memory) or a CD-WORM (Compact-Disc Write-Once-Read-Many). Many acronyms are used to describe the CD and similar optical recording media. 
     In FIG. 1A, it can be seen that the CD  1  comprises several layers, the first of which is a layer of clear polycarbonate  2 . The polycarbonate layer  2  forms the basic substrate for the CD  1 . The next layer  3  is a thin layer of reflective metal film located on the upper side of the polycarbonate disc  2 . This reflective layer  3  is the recording media in the CD  1 . Above the metal layer  3  is a label  4 . The label  4  often consists of silk-screened ink and a protective lacquer coat and forms the top surface of the CD  1 . For CD&#39;s that carry classified data, the label  4  is typically a narrow band near the center of the disc about a central aperture  5 . This aperture  5  is used to position and spin the CD  1  in recording and playback operations. It should be noted that the reflective metal layer  3  and the label  4  are generally very thin in comparison with the polycarbonate substrate  2 , but have been shown relatively-large in FIG. 1A, for the sake of clarity. 
     FIG. 1C shows a bottom view of a CD in which there appears to be a plurality of rings  7 . These “rings”  7  are actually a single, tightly-wound spiraling groove, similar to that found on an audio record disc. The single spiraling groove  7  is located on the top surface of the CD substrate  2 , but is visible only from the lower side, through the clear polycarbonate substrate  2 . The spiraling groove  7  generally cannot be seen from the top of the CD  1 , because the groove is filled in by the metal layer  3 . 
     To read information contained on a CD  1 , the CD is placed in a CD player and rotated about the disc central axis; the disc central axis coincides with the center of the disc aperture  5 . A laser beam, such as beam  6  shown in FIG. 1A, is directed to illuminate precisely-selected portions of the spiral groove  7 . The beam  6  is typically directed from under the CD  1 . More particularly, the laser beam  6  passes through the clear polycarbonate substrate  2  of the CD  1  and travels to the reflective metal layer  3 . 
     Upon striking the reflective metal layer  3 , the laser beam  6  illuminates information-carrying indentations, not shown, located thereupon. In turn, portions of the laser beam  6  are reflected back to an optical sensor, not shown, which produces electrical output that varies in accordance with the reflected laser beam  6 . 
     As described above, it is the reflective metal layer  3 , located near the top of the CD, that carries data. It is, therefore, this information bearing surface  3  which must be distorted if secure data destruction is to be achieved. As used herein, the term secure data destruction refers to destruction that alters a CD  1  so that no intelligible information can be retrieved from the CD. 
     Information is recorded onto CD&#39;s by forming small pits, not shown, at desired locations along the single spiral groove  7 . The pits are typically about 0.5 micrometers wide and 0.833 micrometers long. During playback, the pits are “read” by a 780-nanometer laser diode, the light from which is invisible to the naked eye. 
     The present invention  100  distorts a CD  1  sufficiently to prevent a laser  6  from reading information stored within the groove  7 . This is due to a number of physical changes the rollers  10   a ,  11   a ,  12   a , and  13   a  of the present invention  100  impart on a CD  1  that passes therebetween. Among other things, these changes include distortion of the shape of the pits, movement of the pits from their original positions, displacement of the reflective layer  3  at the base of the pits so that the laser beam  6  is no longer reflected back properly to the optical sensor, “filling in” of the pits by the crushing action of the rollers  10   a ,  11   a ,  12   a , and  13   a , and production of imperfections, on the substrate  2  and reflective surface  3 , that block light  6  from the laser and interfere with laser light reflection. Cooperatively, these physical changes make retrieval of data carried by the information bearing surface  3  (IBS) of a CD  1  impossible. 
     In keeping with the objectives of the present invention, the destruction of information by this method is effective with a wide variety of IBS&#39;s  3 , including those that are aluminum or gold. In this manner, the present invention provides increased utility over the prior art, including abrasive systems limited to the destruction of aluminum IBS&#39;s. 
     During use of the present invention  100 , a CD  1  passes between a first roller  12   a  and second roller  11   a  progressively applying pressure to the CD. The CD then continues moving, being forced to pass between a third roller  10   a  and a fourth roller  13   a . The roller surfaces  20  include a fine pattern that is impressed on the CD  1  as the CD travels between the first pair of rollers  11   a ,  12   a  and then between the second pair of rollers  10   a , 13   a . One preferred pattern  20  is seen in FIG.  5 . As the CD  1 , passes among the rollers  10   a , 11   a , 12   a , and  13   a , the reflective information bearing layer  3  is distorted and subsequent retrieval of data on that layer is prevented. 
     In keeping with the objectives of the present invention, the fine pattern  20  advantageously does not destroy an identification label  4  printed on the CD  1 . As a result, the CD  1  may still be identified for archival purposes, even after the data contained on the disc  1  is no longer readable. 
     FIG. 2 shows a pictorial view of the present invention  100 . As described above, the present invention  100  includes a first pair of rollers  10   a , 11   a  and a second pair of rollers  12   a , 13   a . A first driving gear  10   b  is disposed on the first gear  10   a , and a second driving gear  12   b  is disposed on the third roller  12   a.    
     The driving gears  10   b , 12   b  are coplanar and sized so that gear  10   b  engages gear  12   b  during rotation. With this arrangement, when the first roller  10   a  rotates, the first drive gear  10   b  engages the second drive gear  12   b , thereby rotating the third roller  12   a . This ensures that the device  100  will force a CD  1  through both sets of rollers  10   a , 11   a  and  12   a , 13   a  with continued rotation of the drive gears  10   b , 12   b . Other numbers of drive gears may also be used, if desired. 
     In operation, a CD disc  1  is forced between the first set of rollers  11   a ,  12   a  and then through the second set of rollers  10   a , 13   a . As seen in FIGS. 2 and 3, the second pair of rollers  12   a , 13   a  is laterally offset from the first pair of rollers  10   a , 11   a.    
     In a preferred embodiment, the clearance between the first roller  10   a  and the second roller  11   a  is approximately ten thousandth of an inch. The clearance between the third roller  12   a  and the fourth roller  13   a  is also approximately ten thousandth of an inch. By comparison, a typical CD  1  is approximately fifty thousandths of an inch thick. As a result of this size difference, the two pairs of rollers  10   a , 11   a  and  12   a , 13   a  cooperatively compress a CD  1  passing therebetween. AS the disc is compressed, the patterns on the roller surfaces  20  become embossed into the top  4  and bottom surfaces  2  of the CD  1 . Although a preferred pattern  20  on the rollers is shown is FIG. 5 to be a diamond-shaped pattern, other patterns would also suffice; rollers having flat surfaces may also be used. 
     As described above, there is an optimum clearance distance between the rollers within a pair  10   a , 11   a  and  12   a , 13   a  that produces desired destruction of the IBS  3 . If rollers within a pair  10   a , 11   a  and  12   a , 13   a  are spaced apart too far, the IBS  3  will not be sufficiently disturbed to totally destroy all the information on the disc  1 . However, excessive pressure, due to rollers  10   a , 11   a  and  12   a , 13   a  that are too close can cause large, information-carrying segments of the IBS  3  to flake off. Although the spacing roller is set at the factory, it may be maintained in the field. 
     FIG. 4 shows a partial view of a CD  1  that has passed through the first and second pairs of rollers  10   a , 11   a , and  12   a , 13   a  of the present invention  100 . As shown in FIG. 4, the reflective metal layer  3  becomes riddled with distorted areas  3   a , formed by lines of distortion  3   b . After a CD  1  passes through the rollers  10   a , 11   a , 12   a , and  13   a , substantially the entire reflective layer  3  is characterized by areas of distortion  3   a ; the information previously stored on the CD is destroyed. 
     As noted above and shown in FIG. 3, the drive gears  10   b ,  12   b  engage one another. For example, driving gear  10   b  and attached roller  10   a  in a clockwise direction will turn gear  12   b  and attached roller  12   a  in a counter clockwise direction. This cooperative rotation will force a compact disc  1  between, and past, the first set of rollers  10   a , 11   a . As the CD  1  emerges from between the first set of rollers  10   a , 11   a , the CD will continue moving into the second set of rollers  12   a , 13   a . Continued rotation of the drive gears  10   b , 12   b  produces continued rotation of the rollers  10   a , 11   a , 12   a , and  13   a , thereby forcing the disc  3  between and past the second pair of rollers  12   a , 13   a . If more driving friction is needed, additional drive gears may be added, as mentioned above. 
     With reference to FIG. 5, a front elevation view of the first upper roller  10   a  is shown. The other rollers  11   a , 12   a , and  13   a  have a similar appearance, and the description of the first roller  10   a  will serve to describe the remaining rollers  11   a , 12   a , and  13   a . Trunnions  22  extend from each end of the roller  10   a . During use, the trunnions  22  rotatably extend through bearing plates  24 , 26  thereby allowing the roller  10   a  to turn in a supported manner. The bearing plates  24 , 26  may include roller mounting apertures, not shown, having ball bearings, not shown, to reduce friction between the bearing plates  24 , 26  and the roller trunnions  22 . 
     With reference to FIG. 3, the drive assembly  28  of the present invention  100  is shown. As seen in FIG. 3, a single drive belt  14  links a drive pulley  16  with a motor pulley  15   a . As will be described below, the drive pulley  16  is connected to the first roller  10   a . More particularly, the drive pulley  16  is axially aligned with, and adjacent to, the first drive gear  10   a . Rotation of the motor pulley  15   a  causes the drive  14  belt to rotate, thereby rotating the first drive gear  10   a  and the first roller  10   a . Continued rotation of the drive pulley  14  will produce tandem rotation of the roller pairs  10   a , 11   a  and  12   a , 13   a , as a CD is forced therebetween, as described above. 
     Although the drive assembly  28  has been described as including a drive belt  14 , motor pulley  15   a , a drive pulley  16  other arrangements could also be used. For example, the belt and pulley arrangement shown in FIG. 3 may replaced by a drive chain  14 ′ and associated gears  15   a ′,  16 ′, as shown in FIG.  2 . 
     As can be seen in FIG. 3, the drive assembly  28  includes a motor  15 , a motor pulley  15   a  mounted on the drive shaft of motor  15 , and a drive pulley  16 . As mentioned above, a drive belt  14  links the motor pulley  15   a  with the drive pulley  16 . As the shaft of the motor  15  rotates in a clockwise direction, the motor pulley  15   a , drive pulley  16 , and gear  11   b  are also driven in a clockwise direction. 
     It is noted that although the present invention has been described in terms of destroying in formation on compact discs, the present invention is not only useful for rendering data on compact discs unintelligible. The present invention could also be used to render unintelligible data on a variety of recording media, including, but not limited to analog phonograph records, digital video discs (DVD&#39;s), and laser video discs. 
     Although the invention has been described in terms of a specific embodiment, it will be readily apparent to those skilled in this art that various modifications, rearrangements and substitutions can be made without departing from the spirit of the invention. The scope of the invention is defined by the claims appended hereto.