Abstract:
A combination of software and hardware renders the computer screen incomprehensible to onlookers. The software consists of a computer program that scrambles the organization of the image on the computer screen. The hardware consists of a set of glasses that reorganizes the scrambled image on the computer screen so that the authorized user can comprehend the image. In an alternate embodiment, the scrambled image is transmitted by cable or wireless transmission to a set of display glasses with an embedded personal display computer that unscrambles the image for viewing at the display glasses.

Description:
BACKGROUND 
   Field of the Invention 
   The present invention is directed to an apparatus and method of preventing unauthorized users from viewing a computer screen. 
   The use of laptop computers in public spaces such as airports, airplanes, and hotel lobbies raises security implications regarding unauthorized viewing by individuals who may be able to see the screen. Additionally, tracking the release of sensitive information can be difficult since unauthorized viewers do not get direct access to the information through a computer and thus do not leave a digital fingerprint from which they could later be identified. Thus, a need exists for an apparatus and method for providing security on computer screens. 
   Video and image scrambling is a common topic in the prior art (See e.g. U.S. Pat. No. 5,841,863 and U.S. Pat. No. 5,161,188). However, the prior art focuses on the need for scrambling video images at a source, transmitting the scrambled image over various means, and then unscrambling the image at the destination. This method of scrambling and unscrambling is useful for data transmission; however it does not prevent an unauthorized user from viewing the unscrambled image at the destination. What is needed beyond the prior art is an apparatus and method for scrambling a computer screen that will allow the image to be viewed by the authorized user, but will render the computer screen unreadable to unauthorized users. 
   U.S. Pat. No. 5,863,075 (Rich) discloses an apparatus and method for scrambling and unscrambling images using a plurality of scrambling and unscrambling screens. The intended image is printed on one screen and can be combined with a seemingly random assortment of other lines and shapes. An unscrambling screen is used to filter out the additional lines and shapes so that the combination of the screens reveals the intended image. However, Rich is limited in that the unscrambling screen must be placed directly upon the scrambled image to view the image. In addition, once the image is unscrambled, the image can be viewed by anyone within the vicinity of the image. What is needed beyond Rich is an apparatus and method for scrambling and unscrambling images in which only the intended viewer is ale to view the image. 
   Therefore, a need exists for an apparatus and a method of preventing casual onlookers from obtaining information on a computer screen. A need also exists for an apparatus and a method of providing additional security for computers by encrypting the computer screen in a way that it is only viewable by a single individual. 
   SUMMARY OF THE INVENTION 
   The present invention meets the needs stated above by utilizing a combination of software and hardware that renders the computer screen incomprehensible to onlookers. The software consists of a computer program that scrambles the organization of the image on the computer screen. The scrambling program can start automatically during the computer boot up and the computer display will only show the scrambled information. The hardware consists of a set of glasses that reorganizes the scrambled image on the computer screen so that the authorized user can comprehend the image. The glasses contain lenses consisting of a unique arrangement of smaller square lenses tiled together to form a full size eyeglass lens. The smaller lenses correspond to the break-up pattern used by the software to scramble the computer screen. When the invention is utilized, the screen is incomprehensible to the normal viewer. However, a viewer equipped with the correct glasses will see the unscrambled image. Another feature of the present invention occurs when the computer is stolen by an unauthorized person who does not have access to the appropriate glasses. In this case, an attempt to view the information on the computer by the unauthorized user would be unsuccessful because the display image is scrambled at the software level. In an alternate embodiment, the scrambled image is transmitted by cable or wireless transmission to a set of display glasses with an embedded personal display computer that unscrambles the image for viewing at the display glasses. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  is a depiction of a distributed data processing system; 
       FIG. 2  is a depiction of a server computer; 
       FIG. 3  is a depiction of a client computer; 
       FIG. 4A  is a depiction of a desktop computer with external display screen; 
       FIG. 4B  is a depiction of a laptop computer with built-in display screen; 
       FIG. 5A  is a depiction of N×M array on a computer screen where N−3 and M=3; 
       FIG. 5B  is a depiction of an N×M array of convex lenses for eyeglasses where N=3 and M=3; 
       FIG. 5C  is a depiction of a first scrambled image on an 3×3 array on a computer screen and the corresponding descrambled image seen through an E×E array of convex lenses; 
       FIG. 5D  is a depiction of a second scrambled image on an 3×3 array on a computer screen and a the corresponding descrambled image seen through a 3×3 array of convex lenses; 
       FIG. 6  is a diagram of the image inversion caused by a convex lens; 
       FIG. 7  is a flow chart for the image scrambling process; 
       FIG. 8A  is a flow chart of the image scrambling process when used with codewords and display glasses; 
       FIG. 8B  is a depiction of the display glasses and connecting cable configuration; 
       FIG. 8C  is a schematic of the personal display computer; and 
       FIG. 9  is a flow chart of the personal display computer program. 
   

   DESCRIPTION OF PREFERRED EMBODIMENT 
     FIG. 1  depicts a pictorial representation of a distributed data processing system in which the present invention may be implemented and is intended as an example, and not as an architectural limitation, for the processes of the present invention. Distributed data processing system  100  is a network of computers which contains a network  102 , which is the medium used to provide communication links between the various devices and computers connected together within distributed data processing system  100 . Network  102  may include permanent connections, such as wire or fiber optic cables, or temporary connections made through telephone connections. In the depicted example, a server  104  is connected to network  102  along with storage unit  106 . In addition, clients  108 ,  110 , and  112  also are connected to a network  102 . Clients  108 ,  110 , and  112  may be, for example, personal computers or network computers. 
   For purposes of this application, a network computer is any computer, coupled to a network, which receives a program or other application from another computer coupled to the network. In the depicted example, server  104  provides Web based applications to clients  108 ,  110 , and  112 . Clients  108 ,  110 , and  112  are clients to server  104 . Distributed data processing system  100  may include additional servers, clients, and other devices not shown. In the depicted example, distributed data processing system  100  is the Internet with network  102  representing a worldwide collection of networks and gateways that use the TCP/IP suite of protocols to communicate with one another. Distributed data processing system  100  may also be implemented as a number of different types of networks, such as, an intranet, a local area network (LAN), or a wide area network (WAN). 
   Referring to  FIG. 2 , a block diagram depicts a data processing system, which may be implemented as a server, such as server  104  in  FIG. 1  in accordance with the present invention. Data processing system  200  may be a symmetric multiprocessor (SMP) system including a plurality of processors such as first processor  202  and second processor  204  connected to system bus  206 . Alternatively, a single processor system may be employed. Also connected to system bus  206  is memory controller/cache  208 , which provides an interface to local memory  209 . I/O bus bridge  210  is connected to system bus  206  and provides an interface to I/O bus  212 . Memory controller/cache  208  and I/O bus bridge  210  may be integrated as depicted. Peripheral component interconnect (PCI) bus bridge  214  connected to I/O bus  212  provides an interface to first PCI local bus  216 . Modem  218  may be connected to first PCI bus local  216 . Typical PCI bus implementations will support four PCI expansion slots or add-in connectors. Communications links to network computers  108 ,  110  and  112  in  FIG. 1  may be provided through modem  218  and network adapter  220  connected to first PCI local bus  216  through add-in boards. Additional PCI bus bridges such as second PCI bus bridge  222  and third PCI bus bridge  224  provide interfaces for additional PCI local buses such as second PCI local bus  226  and third PCI local bus  228 , from which additional modems or network adapters may be supported. In this manner, server  200  allows connections to multiple network computers. A memory-mapped graphics adapter  230  and hard disk  232  may also be connected to I/O bus  212  as depicted, either directly or indirectly. Those of ordinary skill in the art will appreciate that the hardware depicted in  FIG. 2  may vary. For example, other peripheral devices, such as an optical disk drive and the like also may be used in addition or in place of the hardware depicted. The depicted example is not meant to imply architectural limitations with respect to the present invention. The data processing system depicted in  FIG. 2  may be, for example, an IBM RISC/System 6000 system, a product of International Business Machines Corporation in Armonk, N.Y., running the Advanced Interactive Executive (AIX) operating system. 
   With reference now to  FIG. 3 , a block diagram illustrates a data processing system in which the invention may be implemented. Data processing system  300  is an example of either a stand-alone computer, if not connected to distributed data processing system  100 , or a client computer, if connected to distributed data processing system  100 . Data processing system  300  employs a peripheral component interconnect (PCI) local bus architecture. Although the depicted example employs a PCI bus, other bus architectures such as Micro Channel and ISA may be used. Processor  302  and main memory  304  are connected to PCI local bus  306  through PCI bridge  303 . PCI bridge  303  also may include an integrated memory controller and cache memory for Processor  302 . Additional connections to PCI local bus  306  may be made through direct component interconnection or through add-in boards. In the depicted example, local area network (LAN) adapter  310 , SCSI host bus adapter  312 , and expansion bus interface  314  are connected to PCI local bus  306  by direct component connection. In contrast, audio adapter  316 , graphics adapter  318 , and audio/video adapter (A/V)  319  are connected to PCI local bus  306  by add-in boards inserted into expansion slots. Expansion bus interface  314  provides a connection for a keyboard and mouse adapter  320 , modem  322 , and additional memory  324 , SCSI host bus adapter  312  provides a connection for hard disk drive  326 , tape drive  328 , and CD-ROM  330  in the depicted example. Typical PCI local bus implementations will support three or four PCI expansion slots or add-in connectors. An operating system runs on processor  302  and is used to coordinate and provide control of various components within data processing system  300  in  FIG. 3 . The operating system may be a commercially available operating system such as OS/2, which is available from International Business Machines Corporation. “OS/2” is a trademark of International Business Machines Corporation. An object oriented programming system, such as Java, may run in conjunction with the operating system and provides calls to the operating system from Java programs or applications executing on data processing system  300 . “Java” is a trademark of Sun Microsystems, Incorporated. Instructions for the operations system, the object-oriented operating system, and applications or programs may be located on storage devices, such as hard disk drive  326 , and they may be loaded into main memory  304  for execution by processor  302 . 
   Those of ordinary skill in the art will appreciate that the hardware in  FIG. 3  may vary depending on the implementation. Other internal hardware or peripheral devices, such as flash ROM (or equivalent nonvolatile memory) or optical disk drives and the like, may be used in addition to or in place of the hardware depicted in  FIG. 3 . Also, the processes of the present invention may be applied to a multiprocessor data processing system. For example, data processing system  300 , if configured as a network computer, may not include SCSI host bus adapter  312 , hard disk drive  326 , tape drive  328 , and CD-ROM  330 , as noted by the box with the dotted line in  FIG. 3  denoting optional inclusion. In that case, the computer, to be properly called a client computer, must include some type of network communication interface, such as LAN adapter  310 , modem  322 , or the like. As another example, data processing system  300  may be a stand-alone system configured to be bootable without relying on some type of network communication interface, whether or not data processing system  300  comprises some type of network communication interface. As a further example, data processing system  300  may be a Personal Digital Assistant (PDA) device that is configured with ROM and/or flash ROM in order to provide non-volatile memory for storing operating system files and/or user-generated data. The depicted example in  FIG. 3  and above-described examples are not meant to imply architectural limitations with respect to the present invention. It is important to note that while the present invention has been described in the context of a fully functional data processing system, those of ordinary skill in the art will appreciate that the processes of the present invention are capable of being distributed in a form of a computer readable medium of instructions and a variety of forms and that the present invention applies equally regardless of the particular type of signal bearing media actually used to carry out the distribution. Examples of computer readable media include recordable-type media, such a floppy disk, a hard disk drive, a RAM, and CD-ROMs, and transmission-type media, such as digital and analog communications links. 
     FIG. 4A  is a depiction of desktop computer  410  having a main computer  420  and a display unit  422 . Display unit  422  has display screen  424 . 
     FIG. 4B  is a depiction of laptop computer  440  having a computer section  450  and display section  452 . Display section  452  has laptop display screen  454 . 
     FIG. 5A  depicts computer screen N×M array (CSA)  510  where N is the number of horizontal screen segments and M is the number of vertical screen segments. In CSA  510 , N−3 because there are three screen segments in horizontal direction  530  and M−3 because there are three screen segments in vertical direction  540 . As used herein a screen segment (CS) is a segment of an image on a computer screen that has sides of equal length. Screen segments can be “tiled” together to form a square or rectangle depending on the values assigned to N and M. As used herein “tiling” means that each segment is adjacent to each segment with which it has a common side so that there are no spaces between segments and an unbroken image can appear on the display screen. In the example of CSA  510 , where N−3 and M=3 there are nine screen segments identified as follows, top left CS  512 , top center CS  514 , top right CS  516 , left center CS  518 , center CS  520 , left center  522 , left bottom CS  524 , bottom center  526 , and right bottom CS  528 . 
     FIG. 5B  depicts lens N×M array (LA)  550  where N is the number of horizontal lens units and M is the number of vertical lens units. In LA  550 , N=3 because there are three lens units in horizontal direction  580  and M=3 because there are three lens units in vertical direction  590 . As used herein, a lens unit means a convex lens that has sides of equal length. As used herein, a lens array means a group of lens units that have been tiled together to form a square or rectangle depending on the values assigned to N and M. As used herein “tiling” means that each lens unit is adjacent to each lens unit with which it has a common side so that there are no spaces between segments and an unbroken image can be seen through the LA. In the example of LA  550 , where N=3 and M=3 there are nine lens units identified as follows, top left LA  552 , top center LA  554 , top right LA  556 , left center LA  558 , center LA  560 , left center LA  562 , left bottom LA  564 , bottom center LA  566 , and right bottom LA  568 . 
   LA  550  is used in conjunction with CSA  510 .  FIG. 6  depicts a convex lens and shows the image inversion achieved by a convex lens. The object in  FIG. 6 , when viewed through the lens is seen completely inverted. The principal axis of a double convex lens is defined as the horizontal axis of the lens across which the lens is symmetrical. Light rays incident towards either face of the lens and traveling parallel to the principal axis will converge, in case of a double convex lens, to point known as the focal point of the lens. The focal point is denoted by the letter F in  FIG. 6 . Each lens has two focal points—one on each side of the lens. Every lens has two possible focal points. The image of an object when viewed through a thin double convex lens will appear inverted as shown in  FIG. 6 . Thus, if the object was inverted originally, when viewed through the thin double convex lens, the image will appear upright. The principle depicted in  FIG. 6  will be employed in conjunction with CSA  510  and LA  550  to scramble the image displayed on a computer screen and then to unscramble the image when viewed through LA  550 . Scrambling is achieved by dividing a computer screen image into segments and then inverting each of the screen segments. The screen may be viewed unscrambled by viewing the screen through lens array  550 . 
     FIG. 7  is a depiction of scrambling program (SP)  700  that operates within memory  304  of computer  300 . The scrambling program starts ( 710 ) and queries the user to enter values for N and M ( 720 ). Next, the image that is normally displayed on the computer screen is divided into segments ( 730 ). In the preferred embodiment, the segments are squares, which can be tiled together to form the image. However, those skilled in the art of computer programming will appreciate that other types of segments can be formed out of other geometric shapes such as triangles and hexagons. 
   The screen is divided into N×M segments ( 730 ). Each of the screen segments is inverted ( 740 ) so that when viewed through a lens array of corresponding N×M configuration, the images will be seen in their original orientation. While lens units are tiled together in LA  550 , the unscrambled image is formed on the user&#39;s side of LA  550 . In this manner, only the user who wears the glasses is able to view a comprehendible image of the computer screen. To all other users, the computer screen appears to be a garbled compilation of individual images. 
   In the preferred embodiment, inversion of screen segments is used. Additional method of scrambling that may be used are reflection (making the segment image appear backwards), shrinking (making the image appear smaller than its normal size), and rotation (rotating the image about a central point). Those skilled in the arts of computer programming and optics will be aware of the various methods in which a computer screen image can be distorted so that a specific optical lens array can correct the distortion. The arrangement of the distorted segments is such that the compilation of the individual distorted segments is sufficiently different from the original image and prevents unauthorized users from comprehending the image. A determination is made as to whether the user wants to unscramble the image ( 750 ). If the user chooses to unscramble the image, then each N×M screen segment is returned to its original orientation and the unscrambled image will be visible on the computer display screen ( 750 ). If the user does not want to unscramble the image, or after the screen segments have been returned to their original orientation, a determination is made as to whether the scrambler is to be turned off ( 770 ). If the user does not want to turn the scrambler off, then a determination is made whether the user wants to enter new values for N and M to change the configuration of screen segments ( 780 ). If the user does not want to enter new values for N and M, then the scrambling program will go to step  750 . If the user does want to enter new values for N and M, then the scrambling program will go to step  720 . If the user wants to turn the scrambler off, the program will stop ( 790 ). 
   The tiling of lens units within lens array  550  creates a very high number of possible scrambling combinations. The possible combinations are so numerous that it is unlikely that an unauthorized individual will have the exact same pair of glasses as the authorized user. 
     FIG. 8A  depicts augmented scrambling program (ASP)  800  having three additional security features: a password, a code word, and display glasses. As used herein, the term password means any combination of characters used to access the ASP  800 . As used herein, the term codeword means any combination of characters, other than the combination of characters in the password, used to identify a particular set of values for N and M. As used herein, the term display glasses means a set of glasses that displays the computer screen image transmitted by cable or wireless technology from a computer, containing a personal display computer to unscramble a transmitted computer screen image, and so constructed that only the person wearing the glasses can see the transmitted computer screen image. Display glasses are discussed further in  FIGS. 8B and 8C . The ASP  800  begins ( 802 ). A determination is made whether a correct password has been entered ( 804 ). If a correct password had not been entered, then the augmented scrambling program displays an error message ( 806 ) and returns to step  804 . If a correct password has been entered, the scrambled program is activated ( 808 ). Next, a determination is made as to whether a code word has been entered. If a code word is entered, then the program sets N and M corresponding to the values for that particular codeword ( 812 ). If a code word has not been entered, then the scrambling program queries the user to enter N and M. A determination is made whether display glasses are connected. If display glasses are connected, the computer screen image is transmitted to the display glasses ( 818 ) and ASP  800  proceeds to step  820 . If the display glasses are not connected, then ASP  800  proceeds to divide the screen segments into N×M segments and each screen segment is inverted ( 820 ). As will be further discussed below, when using display glasses for viewing the screen segments, a greater variety of scrambling techniques can be used. In the preferred embodiment, inversion of screen segments is used. As noted with SP  700 , additional methods of scrambling that may be used are reflection (making the segment image appear backwards), shrinking (making the image appear smaller than its normal size), and rotation (rotating the image about a central point). However, when using display glasses, the method of scrambling is only limited by the operations performed on each of the N×M screen segments. A determination is made as to whether a new code word has been entered ( 822 ). If a new code word has been entered, then the scrambling program goes to step  812 . If a new code word has not been entered, then a determination is made as to whether the scrambler has been turned off ( 824 ). If the scrambler has not been turned off, then the program continues ( 826 ) and returns to step  824 . If the scrambler has been turned off, then each N×M segment is returned to its original orientation ( 828 ) and the scrambling program stops ( 830 ). 
     FIG. 8B  depicts display glasses  840  having frame  842 , top  844 , personal display screen  850 , and personal display computer  870 . Personal display screen  850  has inside surface  854  and outside surface  852 . Outside surface  852  is opaque. Top  844  keeps light from interfering with viewing of images on inside surface  854 . In the preferred embodiment, inside surface  854  is a liquid crystal display (LCD). However, inside surface  854  is not limited to an LCD display and inside surface  854  may use any suitable type of display technology known to persons skilled in the art. Frame  842  secures display glasses  840  to the head of the user. Personal display screen  850  has personal display computer  870  embedded so that personal display screen  850  and personal display computer are of unitary external construction. In an alternate embodiment, personal display computer may be externally attached to either top  844 , frame  842  or personal display screen  850  and electrically connected to personal display screen  850 . Connecting cable  860  has display glasses connector  862  connected to computer connector  864  by cable  866 . Frame  842  has connecting port  846  for receiving display glasses connector  862 . Computer connector  864  may be any suitable connector known to a person skilled in the art. Display glasses  840  may be connected to a computer by either connecting cable  860  or by a wireless connection such as bluetooth technology. 
     FIG. 8C  depicts personal display computer (PDC)  870  having PDC microprocessor  872 , PDC memory  874 , PDC transmitter/receiver  876  and PDC cable connector  878 . PDC memory  874  is connected to PDC microprocessor  872  by first line  886 . PDC cable connector  878  is connected to PDC microprocessor  872  by second line  880 . PDC transmitter/receiver is connected to PDC microprocessor  872  by third line  884 . PDC microprocessor  872  is connected to personal display screen  850  by fourth line  882 . In the preferred embodiment, PDC transmitter/receiver  876  uses bluetooth technology to electronically connect display glasses  840  to a computer having either SP  700  or ASP  800  in memory. In addition, server  104  ( FIG. 2 ), data processing system  300  ( FIG. 3 ), desktop computer  410  ( FIG. 4A ) and laptop computer  440  ( FIG. 4B ) may all be provided with bluetooth technology or other suitable transmitting/receiving technology known to those skilled in the art for use with display glasses  840 . 
     FIG. 9  depicts a flow chart for personal display computer program (PDCP)  900 . PDCP  900  is placed in memory  874  of PDC  870 . PDCP  900  starts when display glasses  840  are connected to an external computer, having ASP  800  in the memory of that computer, by either connecting cable  860  or transmission from the computer to PDC transmitter/receiver  876 . PDCP  900  transmits and connects with the external computer ( 904 ). PDCP  900  receives a transmission from the external computer containing an N×M array of scrambled screen segments ( 906 ). PDCP  900  determines whether a code word is contained in the transmission ( 908 ). If a code word is not contained in the transmission, then PDCP  900  accesses the N×M default parameters ( 910 ) in PDC memory  874 . If a code word is contained in the transmission, then PDCP accesses the N×M parameters stored in PDC memory  874  for that codeword ( 912 ). PDCP  900  then restores the scrambled images for the N×M array of image segments to their original configuration ( 914 ) so that the viewer using personal display glasses  840  will view the image in its unscrambled form. PDCP  900  determines whether a new code word has been received ( 916 ). If a new codeword has been received, then PDCP  900  goes to step  912 . If a new codeword has not been received, then PDCP  900  determines whether the transmission is over ( 918 ). If the transmission is not over, then PDCP goes to step  916 . If the transmission is over, then PDCP ends ( 920 ). 
   It will be understood from the foregoing that various modifications and changes may be made in the preferred embodiment of the present invention by those skilled in the art without departing from its true spirit. It is intended that this description is for purposes of illustration only and should not be construed in a limiting sense. The scope of the invention should be limited only by the language of the following claims.