Abstract:
An electronic device and a remote device cooperate to enable a display of an electronic device when a distance between the electronic device and the remote device is less than a transmit range and to disable the display when the distance is greater than the transmit range. Disabling the display of the electronic device may improve the security of data on display. Moreover, the disabling and enabling of the display may be carried out automatically, thereby possibly relieving the authorized user from logging out or powering-off the electronic device to secure the display. When the authorized user carries the remote device, the display may be enabled and disabled as the user moves relative to the electronic device. The display of the electronic device may be enabled when the electronic device and the remote device are located within a first distance and the display is disabled when the remote device is located a second distance from the remote device, wherein the second distance is greater than the first distance. For example, when the user carries the remote device, the display is enabled when the user is within a first distance from the electronic device. When the user carriers the remote device to a second greater distance from the electronic device, the display is enabled.

Description:
FIELD OF THE INVENTION 
     The present invention relates the field of displays in general and more particularly to security for displays. 
     BACKGROUND OF THE INVENTION 
     Sensitive data or applications are sometimes run on computers which may not be located in secure environments. For example, personnel data may be accessed in an employee&#39;s office or cubicle in which it may be difficult to prevent unauthorized persons from seeing sensitive data or using the application when the computer is unattended by the authorized user. Moreover, as mobile electronic devices, such as Personal Digital Assistants (PDAs) or laptop computers, become more widely used, sensitive data or applications may be run by authorized users outside their offices, thereby further complicating the problem of access or observation by unauthorized users. 
     Authorized users may log-off the application or power-down the computer to avoid unauthorized users from observing or accessing the sensitive data. Unfortunately, these measures may call for the user to remember to manually perform the steps involved which may result in the authorized users forgetting or neglecting to take the preventative measures. Moreover, in cases where the authorized user is frequently away from the computer or other electronic device, logging-out of the application or powering-down the computer may be inconvenient or time consuming. Consequently, there is a need to improve the security of systems which provide access to sensitive data or applications in situations where unauthorized users may be nearby. 
     SUMMARY OF THE INVENTION 
     In view of the above, it is an object of the present invention to provide improved display devices, methods and systems. 
     It is another object of the present invention to allow improvement in the security of electronic device displays. 
     It is a further object of the present invention to allow more convenience securing displays of electronic devices. 
     These and other objects of the present invention can be provided by enabling a display of an electronic device when the electronic device and a remote device, are located within a transmit range of each other and disabling the display when the electronic device and the remote device are not within the transmit range of each other. Disabling the display of the electronic device may improve the security of data on the display. When the authorized user carries the remote device, the display is enabled and disabled as the user moves relative to the electronic device. Consequently, the security of the display may be protected when the authorized user is away from the display. 
     In one aspect of the present invention, the display of the electronic device is enabled when the electronic device and the remote device are located within a first distance and the display is disabled when the remote device is located a second distance from the remote device, wherein the second distance is greater than the first distance. For example, when the user carries the remote device, the display is enabled when the user is within the first distance from the electronic device. When the user carriers the remote device to the second distance from the electronic device, the display is enabled. Carrying the remote device may provide for the enabling and disabling of the display automatically, thereby possibly relieving the authorized user from logging out or powering-off the electronic device to secure the display. 
     In a further aspect of the present invention, the location of the electronic device and the remote device are determined with respect to a transmit range using signals transmitted between the remote device and the electronic device. In one embodiment, the electronic device transmits a transmit signal to the remote device which responds by transmitting a reply signal if the electronic device and the remote device are located within the transmit range of each other. If, however, the electronic device and the remote device are not located; within the transmit range of each other, the remote device does not transmit the reply signal. 
     In another aspect of the present invention, the reply signal includes a first authentication code, such as a pseudo-random code, that the electronic device may use to determine if the reply signal is authentic. For example, when the remote device determines that the electronic device and the remote device are located within the transmit rage of each other, the remote device transmits the reply signal, including the first authentication signal, to the electronic device so that the electronic device can verify that the reply signal originated with the remote device with which the electronic device cooperates. 
     In still another aspect of the present invention, the location of the electronic device and the remote device with respect to each other is determined using a signal threshold level. The signal threshold level corresponds to an expected signal strength of the transmit signal for the transmit range. The strength of the transmit signal received at the remote device is compared to the signal threshold level. If the strength of the transmit signal at the remote device is about equal to or more than the signal threshold level, the electronic device and the remote device can be assumed to be located within the transmit range of each other and the remote device transmits the reply signal. If, however, the strength of the transmit signal at the remote device is less than the signal threshold level, the electronic device and the remote device can be assumed to be located beyond the transmit range of each other and the remote device does not transmit the reply signal. In a preferred embodiment, the signal threshold level is adjustable to select the transmit range. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     FIG. 1 is a diagram of an electronic device and a remote device that cooperate to control a display of the electronic device according to the present invention; 
     FIG. 2 is a block diagram of an embodiment of an electronic device of FIG. 1; 
     FIG. 3 is a flowchart that illustrates operations of an electronic device according to the present invention; 
     FIG. 4 is a block diagram of an embodiment of a remote device of FIG. 1; and 
     FIG. 5 is a flowchart that illustrates operations of a remote device according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. As will be appreciated by one of skill in the art, the present invention may be embodied as methods or devices. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. The present invention is described herein by reference to an electronic device. It will be understood, however, that the electronic device described can be a Personal Data Assistant (PDA), hand-held personal computer, palm-top personal computer, lap-top personal computer, desk-top personal computer or other electronic device having a display. 
     FIG. 1 is a diagram of an electronic device  100  and a remote device  110  that cooperate to control a display  115  of the electronic device  100  according to the present invention. The display  115  of the electronic device  100  is used to provide information to a user. The remote device  110  may be carried by the authorized user as the authorized user moves in relation to the electronic device  100 . According to the present invention, the display  115  is enabled when the electronic device  100  and the remote device  110  are located within a transmit range, R t , of each other. When the electronic device  100  and the remote device  110  are not located within the transmit range of each other, the display  115  is disabled. For example, if the transmit range is 4 feet, when the authorized user carries the remote device  110  more than 4 feet from the electronic device  100 , the display  115  is disabled. When the authorized user carries the remote device  110  to within 4 feet of the electronic device  100 , the display  115  is enabled so that the authorized user may view the information. Consequently, the information provided to the user may be protected from viewing by an unauthorized viewer while the authorized user is more than 4 feet away from the electronic device. In a preferred embodiment, the distance between the electronic device  100  and the remote device  110  is determined by signals transmitted between the electronic device  100  and the remote device  110 . 
     FIG. 2 is a block diagram of an embodiment of an electronic device  100  of FIG. 1. A transmitter  220  transmits a transmit signal to the remote device  110 . The remote device  110  receives the transmit signal and determines if the electronic device  100  and the remote device  110  are located within the transmit range of each other. In other words, the remote device  110  uses the transmit signal to determine if the separation of the electronic device  100  and the remote device  110  exceeds the transmit range. If the separation does not exceed the transmit range, the remote device  110  transmits a reply signal to the electronic device  100  in response to the transmit signal. If, however, the separation exceeds the transmit range, the remote device  110  does not transmit the reply signal to the electronic device  100 , thereby disabling the electronic device  100 . In a preferred embodiment, the electronic device  100  transmits the transmit signal intermittently to reduce the amount of power used by the electronic device  100  and the remote device  110 . 
     The reply signal from the remote device  110  is received at the electronic device  100  by a receiver  215 . The received reply signal is provided to a display controller  210  that enables and disables the display  115  based on the reply signal. A time-out counter  220  counts the time elapsed since the transmit signal was transmitted to the remote device  110 . If the electronic device  100  does not receive an authentic reply signal within a time-out interval, the display controller  210  disables the display  115 . For example, if the remote device  110  moves beyond the transmit range, the remote device  110  will not transmit the reply signal to the electronic device  100  in response to the transmit signal from the electronic device. Consequently, the time-out counter  225  will indicate a time-out condition to the display controller  210  if the time-out interval elapses before an authentic reply signal is received, thereby causing the display controller  210  to disable the display  115 . When the remote device  115  returns to within the transmit range, the authentic reply signal is transmitted by the remote device  110  and received at the electronic device  100  before the time-out interval elapses. Consequently, the display controller  210  enables the display  115 . 
     In a preferred embodiment of the present invention, the reply signal includes a first authentication code, such as a pseudo-random code, that the electronic device  100  uses to determine if the reply signal is authentic. For example, when the remote device  110  determines that the electronic device  100  and the remote device  110  are located within the transmit range of each other, the remote device  110  transmits the reply signal including the first authentication signal to the electronic device  100 . 
     The display controller  210  determines that the first authentication code included in the reply signal identifies the remote device  110  with which the electronic device  100  cooperates to control the display  115 . For example, during an initial set-up procedure, the user may input a password or other data into the electronic device  100  and the remote device  110  to create the first authentication code. Subsequently, the electronic device  100  checks the reply signal for the data or password provided by the user. It will be understood that other types of authentication codes may be used. 
     The first authentication code may provide additional security against an unauthorized remote device masquerading as the authorized remote device  110  to gain access to the sensitive data. If the reply signal does not include the correct first authentication code, the display controller  210  will not enable the display  115 . For example, if an unauthorized user attempts to enable the display by transmitting a false reply signal that includes an incorrect first authentication code, the display controller will not enable the display  115 . 
     FIG. 3 is a flowchart that illustrates operations of an electronic device  100  according to the present invention. According to FIG. 3, the electronic device  100  transmits the transmit signal to the remote device  110  (block  305 ) and waits for a reply from the remote device  100 . If a time-out occurs while waiting for the reply signal to be received (block  310 ), the display  115  is disabled, the time-out counter  225  is reset (block  315 ) and the transmit signal is re-transmitted (block  305 ). 
     If an authentic reply signal is received before a time-out occurs (block  320 ), the display controller  210  enables the display  115 , resets the time-out counter (block  325 ), and transmits another transmit signal (block  305 ). If a non-authentic reply signal is received before a time-out occurs (block  320 ), the electronic device  100  continues to wait for the authentic reply signal (block  310 ) while the time-out interval continues to elapse. 
     FIG. 4 is a block diagram an embodiment of a remote device  110  of FIG.  1 . According to FIG. 4, a receiver  405  receives the transmit signal from the electronic device  100 . The received transmit signal is provided to a processor  415 . The processor  415  uses the transmit signal to determine if the distance between the electronic device  100  and the remote device exceeds the transmit range. If the distance does not exceed the transmit range, the remote device  110  transmits a reply signal to the electronic device  100  using a transmitter  410 . If, however, the distance exceeds the transmit range, the remote device  110  does not transmit the reply signal to the electronic device  100 . 
     In one embodiment of the present invention, the electronic device  100  and the remote device  110  are determined to be located within or beyond the transmit range using a signal threshold level. The signal threshold level corresponds to an expected signal strength of the transmit signal for the transmit range. The strength of the transmit signal received at the remote device  110  is compared to the signal threshold level. If the strength of the transmit signal at the remote device is about equal to or more than the signal threshold level, the electronic device  100  and the remote device  110  are assumed to be located within the transmit range of each other and the remote device  110  transmits the reply signal. If, however, the strength of the transmit signal at the remote device is less than the signal threshold level, the electronic device  100  and the remote device  110  are assumed to be located beyond the transmit range of each other and the remote device  110  does not transmit the reply signal. 
     In general, the strength of the transmit signal received at the remote device decreases as the distance traveled by the transmit signal increases. For example, a first signal strength may be observed at the remote device  110  for a transmit signal that travels 1 meter while a second signal strength, lower than the first signal strength, may be observed for a transmit signal which travels 4 meters. Accordingly, the signal threshold level can be adjusted to select a desired transmit range which is appropriate for the situation. For example, if the authorized user is traveling and desires relatively high security, the signal strength can be set high which corresponds to a relatively short transmit range such as 0.5 to 1 meter. A relatively short transmit range results in the display  115  being disabled when the remote device  110  is moved outside the relatively short transmit range. Alternately, if the authorized user is in his or her office and desires relatively low security, the signal strength can be set low for a relatively long transmit range. 
     In another embodiment of the present invention, the signal strength of the reply signal provided to the remote device  110  may be used to determine if the electronic device  100  and the remote device  110  are located within the transmit of each other. For example, the electronic device  100  may compare the signal strength of the reply signal to a signal threshold level and enable or disable the display based on that determination. It will be understood that other measures of signals may be used to determine the location of the electronic device  100  and the remote device  110  with respect to each other. 
     In a further embodiment of the present invention, the transmit signal includes a second authentication code, such as a pseudo-random code. The second authentication code identifies the electronic device  100  with which the remote device  110  cooperates to control the display  115 . The remote device  110  uses the second authentication code to verify that the transmit signal received originated with the correct electronic device  100 . For example, if multiple systems according to the present invention are being used in proximity to one another, the second authentication code can be used to identify the correct transmit signal from a number of transmit signals transmitted by the other electronic devices  100 . For example, if a palm-top computer utilizing the present invention is located adjacent to the electronic device  100 , the palm-top computer and the electronic device will both transmit respective transmit signals to their respective remote devices  110 . If the authorized user of the palm-top computer moves beyond the respective transmit range associated with the palm-top computer, the second authentication code included in the transmit signal associated with the palm-top computer will not be verified by the remote device  110  for the electronic device  100 . Accordingly, the remote device  110  will not transmit a reply signal to the palm-top, thereby disabling the display of the palm-top. 
     FIG. 5 is a flowchart that illustrates operations of a remote device  110  according to the present invention. According to FIG. 5, the remote device  110  waits to receive the transmit signal from the electronic device  100  (block  505 ). When the transmit signal is received, the processor  415  determines if the electronic device  100  and the remote device  110  are located with the transmit range of each other (block  510 ). 
     If the processor  415  determines that the electronic device  100  and the remote device  110  are located within the transmit range of each other, the processor verifies that the transmit signal includes the correct authentication code (block  515 ). If the transmit signal indicates that the electronic device  100  and the remote device  110  are not located within the transmit range of each other (block  510 ), the remote device  110  does not transmit the reply signal and waits for another transmit signal to be received from the electronic device  100  (block  505 ). If the transmit signal includes the correct authentication code (block  515 ), the processor  415  generates the reply signal and transmits it to the electronic device  100  (block  520 ) and begins waiting for another transmit signal from the electronic device  100  (block  505 ). 
     The present invention is described above using flow chart illustrations. It will be understood that each block of the flowchart illustrations, and combinations of blocks in the flowchart illustrations, can be implemented by computer program instructions. These program instructions may be provided to a processor(s) within the electronic device  100  and remote device  110 , such that the instructions which execute on the processor(s) create means for implementing the functions specified in the flowchart block or blocks. The computer program instructions may be executed by the processor(s) to cause a series of operational steps to be performed by the processor(s) to produce a computer implemented process such that the instructions which execute on the processor(s) provide steps for implementing the functions specified in the flowchart block or blocks. 
     Accordingly, blocks of the flowchart illustrations support combinations of means for performing the specified functions, combinations of steps for performing the specified functions and program instruction means for performing the specified functions. It will also be understood that each block of the flowchart illustrations, and combinations of blocks in the flowchart illustrations, can be implemented by special purpose hardware-based systems which perform the specified functions or steps, or combinations of special purpose hardware and computer instructions. 
     In the drawings and specification, there have been disclosed typical preferred embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being set forth in the following claims.