Abstract:
A system and method for providing enhanced security to signals from a touch panel display, such as the transparent touch panel displays utilized in automatic teller machines, are described. According to one aspect, a varying reference signal is input to a touch panel display. The varying reference signal is utilized by the touch panel display to generate an x-axis signal and a y-axis signal which correspond to a position touched on the touch screen. By varying the reference signal, information entered on the touch screen is difficult to reproduce in a meaningful way by a third party eavesdropping on the x-axis signal and the y-axis signal.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to improvements in touch panel displays. More specifically, the present invention relates methods and apparatus for providing enhanced security to signals from a touch panel display, such as the transparent touch panel displays utilized in automatic teller machines.  
         BACKGROUND OF THE INVENTION  
         [0002]    A transparent touch panel display, or touch screen, produces electrical signals which correspond to a position on the touch screen being touched. Touch screens have found wide spread use as user input devices for electronic transaction terminal devices such as automated teller machines (ATMs) and point of sale (POS) terminals. During certain payment, cash withdrawal, or other transactions, a personal identification number (PIN) is entered on the payment terminal&#39;s touch screen by the user as a form of identification. Since this PIN is considered highly confidential, it could be extremely damaging to the user&#39;s account if a third party was able to eavesdrop on the electrical signals from a touch screen during PIN entry and reproduce those signals during a subsequent transaction to falsely identify themselves as the PIN assignee. As devices such as ATMs are located in less and less carefully supervised locations, efforts at fraud may be more determined and sophisticated. Thus, enhanced security features are highly advantageous.  
           [0003]    Accordingly, it would be highly advantageous to provide enhanced security by preventing a third party from eavesdropping on the electrical signals produced by a touch screen during the entry of confidential information, such as a PIN or the like.  
         SUMMARY OF THE INVENTION  
         [0004]    The present invention advantageously provides methods and apparatus to prevent third parties from eavesdropping on a touch screen and reproducing meaningful information from the electrical signals produced by the touch screen during the entry of a PIN or other confidential information. The touch screen may operate resistively, capacitively, or in another suitable manner. According to one aspect, the present invention provides a varying reference voltage for input to a touch screen panel. The varying reference voltage is utilized by the touch screen to generate an x-axis signal and a y-axis signal which correspond to a position touched on the touch screen. According to another aspect, the present invention provides a varying reference current for input to a touch screen panel.  
           [0005]    A more complete understanding of the present invention, as well as further features and advantages of the invention, will be apparent from the following detailed description and the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    [0006]FIG. 1 shows an automated teller machine in accordance with the present invention;  
         [0007]    [0007]FIG. 2 shows a touch screen in accordance with the present invention;  
         [0008]    [0008]FIG. 3 shows a block diagram of a touch screen and touch screen circuitry in accordance with the present invention;  
         [0009]    [0009]FIGS. 4, 5 and  6  show exemplary varying signal waveforms for use in conjunction with the touch screen and circuitry of FIGS. 2 and 3; and  
         [0010]    [0010]FIG. 7 shows a flowchart of a method of providing enhanced security on a touch screen in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0011]    The present invention now will be described more fully with reference to the accompanying drawings, in which a currently preferred embodiment of the invention is shown. However, this invention may be embodied in various forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, the representative embodiment is described in detail so that this disclosure will be thorough and complete, and will fully convey the scope, structure, operation, functionality, and potential of applicability of the invention to those skilled in the art.  
         [0012]    In the embodiments of the present invention described below, a varying reference signal is used. While the varying reference signal is described in terms of varying voltage, the present invention should not be construed as limited to varying voltage. Other suitable signal characteristics, such as varying current or varying phase, are utilized according to other aspects of the present invention.  
         [0013]    Referring to the drawings, FIG. 1 shows simplified perspective view of a self-service terminal  10 , such as an automated teller machine (ATM), in accordance with the present invention. The ATM  10  includes a touch screen  12 , which is shown in more detail in FIG. 2. The terminal  10  may suitably include other components, depending on the use to which the terminal is applied. For example, there may be a card slot  16  for receiving a user&#39;s ID card, a slot  18  for delivering articles, such as currency notes, to the user, and a receipt slot  20  for issuing a receipt containing details of a transaction effected by the terminal  10 .  
         [0014]    Referring to FIG. 2, there is shown a graphical representation of the touch screen  12  with its x-axis and y-axis labeled for ease of illustration. As described below, when touched, the touch screen  12  produces electrical signals that correspond to the position on the touch screen being touched, allowing the position of the touch to be determined according to its location on the x-axis and y-axis. In the case of a resistive touch screen, the electrical signals from the touch screen  12  are relative to a reference voltage that is applied to the touch screen  12  by external circuitry. By measuring the signals (V X , V Y ) returned from the touch screen  12  at the position of the touch and comparing them to the reference signal V Ref , the position touched can be derived by various known methods. For example, when the touch screen is touched at a position  22  shown in FIG. 2, V X  is approximately {fraction (2/3)} of V Ref  and V Y  is approximately {fraction (1/2)} of V Ref .  
         [0015]    Referring to FIG. 3, there is shown a diagram of touch screen circuitry  30  in accordance with the present invention. The circuitry  30  includes the touch screen  12 , an x-axis analog-to-digital (A/D) converter  32 , an y-axis AID converter  34 , a digital-to-analog (D/A) converter  36 , and a microprocessor  38 . As shown in FIG. 3, the microprocessor  38  is connected to the touch screen  12  through the x-axis A/D converter  32 , the y-axis A/D converter  34 , and the D/A converter  36 .  
         [0016]    The D/A converter  36  receives a digital V Ref  signal  40  generated by the processor  38  and produces a corresponding analog V Ref  signal  42  which is input to the touch screen  12 . The x-axis A/D converter  32  receives an analog V X  signal  44  from the touch screen  12  and produces a corresponding digital V X  signal  46  which is input to the microprocessor  38 . The y-axis A/D converter  34  receives an analog V Y  signal  48  from the touch screen  12  and produces a corresponding digital V Y  signal  50  which is input to the microprocessor  38 . The microprocessor  38  controls the reference voltage  40  and determines the position touched on the touch screen by comparing the V Ref  signal  40  with the digital V X  signal  46  and the digital V Y  signal  50 .  
         [0017]    [0017]FIGS. 4 and 5 show timing diagrams  60  and  70 , respectively, of the signal waveforms resulting from a continuous touch at the position  22  of FIG. 2. As shown in the signal timing diagrams  60  and  70 , the microprocessor  38  provides a varying reference signal V Ref  signal  40  to the D/A converter  36 , which results in a corresponding varying analog V Ref  signal  42  being input to the touch screen  12 . The V X  signal  46  and the V Y  signal  50  returned to the processor are determined with respect to the varying signal  40 . The reference signal V Ref    40  may be varied according to a random generation sequence, a predetermined algorithm, a look-up table, or some other suitable mechanism for controlling voltage variation to substantially decrease the likelihood that an eavesdropper on the signal will gain useful information.  
         [0018]    The reference signal  40  and the signals  46  and  50  are synchronized in time to correctly identify a given position. In other words, the signals  46  and  50  returned from the touch screen  12  at a given point in time are meaningful only when the reference signal  40  at that point in time is known by the microprocessor  38 . Thus, the information entered on the touch screen  12  corresponding to signals  46  and  50  is extremely difficult to reproduce by electronically eavesdropping on signals  44  and  48 . This advantageously prevents a third party from eavesdropping on the touch screen output signals  44  and  48  entered during a valid session and later reproducing those signals during an invalid session to gain illegal access to another person&#39;s funds.  
         [0019]    As an example, assume that a position of the numeral “5” on the touch screen  12  of FIG. 1 corresponds to the point V X (5), V Y (5), where V X (5)=0.6V Ref  and V Y (5)=0.6V Ref , and that a position of the numeral “9” corresponds to the point V X (9), V Y (9), where V X (9)=0.8V Ref  and V Y (5)=0.4V Ref . Further, assume that V Ref  has a range of 0 to 6 volts. FIG. 6 shows an exemplary timing diagram  80  of the signal waveforms resulting from a touch of the numeral “5” at time T 1  followed by a touch of the numeral “9” at time T 2 . At time T 1 , V Ref =3 V and thus V X (5)=1.8V and V Y (5)=1.8V. At time T 2 , V Ref =5V and thus V X (9)=4.5V and V Y (9)=2.0V.  
         [0020]    [0020]FIG. 7 shows a method  90  of providing enhanced security to a touch screen in accordance with the present invention. In a first step  90 , a varying reference signal (such as signal V Ref ) is delivered to a touch screen (such as touch screen  12 ). When the touch screen is touched, in a second step  92 , positional signals (such as positional signals V X  and V Y ) are generated based upon the position touched and the reference signal. In step  94 , the position touched is determined utilizing the positional signals and the value of the reference signal corresponding to the point in time when the screen was touched.  
         [0021]    It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the present invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.