Abstract:
Methods, apparatuses, and systems for processing tactile input received at a display are disclosed. An apparatus may include a display comprising a tactile sensor and a display screen. The tactile sensor may include a top layer comprising a first plurality of resistive strips, wherein each of the resistive strips in the top layer are spaced apart from one another, a bottom layer comprising a second plurality of resistive strips, wherein each of the resistive strips in the bottom layer are spaced apart from one another, and a separator positioned between the first plurality of resistive strips of the top layer and the second plurality of resistive strips of the bottom layer, wherein the tactile sensor is configured to receive a tactile input to cause at least one of the resistive strips of the top layer to contact at least one of the plurality of resistive strips of the bottom layer.

Description:
FIELD 
       [0001]    Example embodiments of the invention generally relate to touch screen technology. More specifically, example embodiments of the invention relate to a resistance based multi-point touch screen. 
       BACKGROUND 
       [0002]    Mobile phones, computers, and other devices typically have displays to visually present information to a user. Touch screen technology may receive and process a single touch or multiple simultaneous touches from a user at a display screen. Single touch screens are often based on resistive technologies that identify user input by measuring a change in resistance caused by a user touching a certain area on the display. Conventionally, single touch screens can only detect a single input from a user at a time, and cannot detect two or more near simultaneous touches. 
         [0003]    Multi touch screens are becoming increasingly popular for devices as they can process tactile information input by a user simultaneously touching multiple locations on a display. Three types of conventional multi touch screens include: a capacitive type, a switch matrix type, and an optical type. Known types of multi touch screens, however, are based on complex and expensive technology. The manufacturing of the three types of multi touch screens is more complex than that of resistive touch screens. Multi touch screens also require very complex signal processing methods and very complex processing circuits. Hence, the cost of all the three kinds of known multi touch screens is higher than that of resistive touch screens. 
         [0004]    Processing handwriting on a display input by a user can be challenging based on current touch screen technology. Handwriting requires a touch screen having high resolution. To obtain good results, the touch panel and the resolution of the display screen may have about the same resolution. Capacitive type multi touch screens have lower resolution than resistive touch screens, thus they are currently unable to satisfactorily support handwriting input. For the switch matrix and optical type multi touch screens, a higher resolution requires complex manufacturing techniques, signal processing, and circuitry, which results in higher cost. 
       BRIEF SUMMARY 
       [0005]    The following presents a simplified summary of example embodiments of the invention in order to provide a basic understanding of some example embodiments of the invention. This summary is not an extensive overview, and is not intended to identify key or critical elements or to delineate the scope of the claims. The following summary merely presents some concepts and example embodiments in a simplified form as a prelude to the more detailed description provided below. 
         [0006]    Some example embodiments provide for processing multiple simultaneous tactile inputs using resistive touch screen technology. 
         [0007]    Some example embodiments of the present disclosure are directed to an apparatus, method and system for sequentially applying an electrical pulse to an electrode of respective resistive strips, the resistive strips being included in one of the top layer and the bottom layer; sequentially measuring resistance across resistive strip pairs as the electrical pulse is being applied to at least one of the resistive strips in a resistive strip pair, wherein each resistive strip pair includes a resistive strip from the top layer and a resistive strip from the bottom layer, detecting a change in the resistance of a first resistive strip pair due to tactile input during sequential resistance measurement, and determining coordinates of the tactile input on the first resistive strip pair. 
         [0008]    Additionally, methods, apparatus, and systems in accordance with certain example embodiments of the present disclosure provide a display comprising a tactile sensor and a display screen. The tactile sensor may include a top layer comprising a first plurality of resistive strips, wherein each of the resistive strips in the top layer are spaced apart from one another, a bottom layer comprising a second plurality of resistive strips, wherein each of the resistive strips in the bottom layer are spaced apart from one another, and a separator positioned between the first plurality of resistive strips of the top layer and the second plurality of resistive strips of the bottom layer, wherein the tactile sensor is configured to receive a tactile input to cause at least one of the resistive strips of the top layer to contact at least one of the plurality of resistive strips of the bottom layer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    A more complete understanding of the present invention and the advantages thereof may be acquired by referring to the following description in consideration of the accompanying drawings, in which like reference numbers indicate like features, and wherein: 
           [0010]      FIG. 1  illustrates a user terminal incorporating a multi-touch display screen in accordance with one or more example embodiments of the present disclosure. 
           [0011]      FIG. 2  illustrates an exploded view of a multi-touch display screen of a user terminal in accordance with one or more example embodiments of the present disclosure. 
           [0012]      FIG. 3  illustrates a front view of both of top and bottom layers of a tactile sensor in accordance with one or more example embodiments of the present disclosure. 
           [0013]      FIG. 4  illustrates a front view of a top layer without a bottom layer of a tactile sensor in accordance with one or more example embodiments of the present disclosure. 
           [0014]      FIG. 5  illustrates a front view of a bottom layer without a top layer of a tactile sensor in accordance with one or more example embodiments of the present disclosure. 
           [0015]      FIG. 6  illustrates a cross sectional view of an embodiment of a tactile sensor in accordance with one or more example embodiments of the present disclosure. 
           [0016]      FIG. 7  illustrates a cross sectional view of an embodiment of a tactile sensor in accordance with one or more example embodiments of the present disclosure. 
           [0017]      FIG. 8  illustrates electrical pulses being applied to resistive strips of a bottom layer of a tactile sensor in accordance with one or more example embodiments of the present disclosure. 
           [0018]      FIG. 9  illustrates resistive strips of a top and bottom layer of a tactile sensor that have been contacted by a user in accordance with one or more example embodiments of the present disclosure. 
           [0019]      FIG. 10  illustrates a measuring principle for determining coordinates of a contact point in accordance with one or more example embodiments of the present disclosure. 
           [0020]      FIG. 11  illustrates a method performed by a user terminal in accordance with one or more example embodiments of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    In the following description of the various embodiments, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration various embodiments in which one or more example embodiments of the invention may be practiced. It is to be understood that other embodiments may be utilized and structural and functional modifications may be made without departing from the scope of the present invention. 
         [0022]      FIG. 1  illustrates a user terminal  100  incorporating a multi-touch display screen  102  in accordance with one or more example embodiments of the present disclosure. The user terminal  100  may be a mobile communication device, as illustrated, or may be a computer, a personal digital assistant, a watch, an Internet browser device, a wired or wireless communication device, combinations thereof, and/or other devices that display text, graphics video, and/or any combination thereof to a user. In the depicted example, the user terminal  100  includes a multi-touch display screen  102 , a display generator  104 , a processor  106 , memory  108  or other computer readable media and/or other storage, and user interface  110 . The user interface  110  may include a keypad, touch screen, voice interface, four arrow keys, joy-stick, data glove, mouse, roller ball, touch screen, or other suitable device for receiving input from a user to control the user terminal  100 . 
         [0023]    Computer executable instructions and data used by processor  106  and other components within user terminal  100  may be stored in the memory  108  in order to carry out any of the method steps and functions described herein. The memory  108  may be implemented with any combination of read only memory modules or random access memory modules, optionally including both volatile and nonvolatile memory. Also, some or all of user terminal  100  computer executable instructions may be embodied in hardware or firmware (not shown). The user terminal  100  may also have other components that are not depicted, or the functionality of the depicted components may be integrated with one another or separated into further components local or remote to the user terminal  100 . For instance, the processor  106  and the display generator  104  may be combined, or the operations of the processor  106  may be performed by separate processors remote or local to the user terminal  100 . 
         [0024]      FIG. 2  illustrates an exploded view of the multi-touch display screen  102  of a user terminal  100  in accordance with one or more example embodiments of the present disclosure. In various embodiments, the multi-touch display screen  102  may include a tactile sensor  202  and a display screen  204 . The multi-touch display screen  102  may be positioned in a housing of the user terminal  100  with the tactile sensor  202  being external to the display screen  204 . The tactile sensor  202  may include multiple electrodes  206  surrounding two layers of resistive strips. The resistive strips may comprise translucent conductive materials, such as, but not limited to, Indium Tin Oxide (ITO).  FIG. 3  illustrates a front view of overlapping top and bottom layers of the tactile sensor  202 ,  FIG. 4  illustrates a front view of the top layer of resistive strips without the bottom layer of resistive strips, and  FIG. 5  illustrates a front view of the bottom layer without the top layer. It is noted that the order of the top layer and the bottom layer may be reversed, with the bottom layer being on top and the top layer being on the bottom. 
         [0025]    With reference to  FIGS. 4 and 5 , each of the top and bottom layers may include a row of resistive strips  402 . An electrode  206  may be positioned at each end of each resistive strip  402 . The resistive strips  402  may be bar-shaped and may be perpendicular to the electrodes  206 . Referring to  FIG. 4 , the resistive strips  402  may be of width w and each resistive strip  402  in a layer (i.e., in the top layer or in the bottom layer) may be separated from adjacent resistive strips by a gap of distance d. Width w may vary adjusted to suit different designs, but may be as narrow as the width of a nib of a stylus (e.g., 2 millimeters) or as wide or wider than the width of a finger (e.g., 20 millimeters). The gap of distance d may vary adjusted to suit different designs, but may be as narrow as possible depending on manufacturing limitations. The width w may be adjusted, for example, based on the average size of the width of a finger or based on the width of a stylus used to touch the multi-touch display screen  102 . Although the resistive strip  402  having arbitrary widths w can be designed, the multi-touch display screen  102  may be designed such that at least two or more resistive strips  402  are used per layer (e.g., at least two resistive strips in the top layer and at least two resistive strips in the bottom layer). 
         [0026]      FIGS. 6 and 7  illustrate cross sectional views of two embodiments of the tactile sensor  202  in accordance with one or more example embodiments of the present disclosure.  FIG. 6  illustrates a cross sectional view of the tactile sensor  202  along line A-A′ in  FIG. 3  in accordance with a first embodiment, and  FIG. 7  illustrates a cross sectional view of the tactile sensor  202  along line A-A′ in  FIG. 3  in accordance with a second embodiment.  FIGS. 6 and 7  illustrate different embodiments of separators that may be used to separate the top and bottom layers.  FIG. 6  describes separators that can be spacers and  FIG. 7  describes separators that can be a resistive layer. 
         [0027]      FIG. 6  illustrates spacers  602  positioned between the resistive strips  402 T of the top layer and the resistive strips  402 B of the bottom layer. The spacers  602  may contact each of the bottom and top layer resistive strips, or may be attached to one of the bottom and top layer resistive strips. The spacers  602  may be positioned to cover each gap of distance d between the resistive strips  402 B in the bottom layer and beneath the resistive strips  402 T of the top layer. The spacers  602  may be insulators. The spacers  602  may electrically and physically isolate the top layer and the bottom layer to prevent the two layers from contacting without receiving a touch from a user. The spacers  602  also may act as partitions so that contact may occur between the contacted strips in the top and bottom layers. Where there is no contact between the layers, the processor  106  may measure a high resistance between any resistive strip  402 T from the top layer and any resistive strip  402 B from the bottom layer. 
         [0028]    When a user contacts the top layer, a bottom surface of resistive strip  402 T of the top layer may deflect to contact a top surface of resistive strip  402 B of the bottom layer. For example, a user may press resistive strip  402 T to cause the bottom surface of resistive strip  402 T to contact the resistive strip  402 B_ 2 . This contact can produce a change in resistance between the contacted pair of resistive strips  402  at the contact location, where a resistive strip pair may include a resistive strip  402 T from the top layer and a resistive strip  402 B from the bottom layer. 
         [0029]    The force of the contact applied by the user may adjust an electrical resistance between the resistive strips in a resistive strip pair. Pressing the flexible resistive strip  402 T can create electrical contact between a top layer resistive strip  402 T and a bottom layer resistive strip  402 B. As discussed in further detail below, the user terminal  100  may scan the resistance of resistive strip pairs by sequentially applying electrical pulses at the respective electrodes  206  to determine at which resistive strip pair the tactile input was received. In addition to spacers  602 , the tactile sensor  202  also may include a resistive layer between the top layer and the bottom layer. 
         [0030]      FIG. 7  illustrates a resistive layer  702  positioned between the resistive strips  402 T of the top layer and the resistive strips  402 B of the bottom layer in accordance with example embodiments of the present disclosure. The resistive layer  702  may be a material having a property where its resistance may change in response to a touch. For example, the material may be a piezoresistive material. 
         [0031]    When a user makes contact with a resistive strip  402 T of the top layer, a bottom surface of the top layer resistive strip  402 T may come into contact with the resistive layer  702  and may cause the resistive layer  702  to contact a top surface of resistive strip  402 B of the bottom layer. Accordingly, the resistive strip  402 T may indirectly contact the resistive strip  402 B through the resistive layer  702 . This contact can change the electrical resistance at the contact location. As discussed in further detail below, the user terminal  100  may scan the resistance of resistive strip pairs by sequentially applying electrical pulses at the respective electrodes  206  to determine at which resistive strip pair the tactile input was received. It is noted that  FIG. 6  illustrates only spacers  602 , and  FIG. 7  illustrates only resistive layer  702 , but a combination of spacers  602  and resistive layers  702  also may be used. 
         [0032]      FIG. 8  illustrates electrical pulses being applied to resistive strips of the bottom layer of a tactile sensor in accordance with example embodiments of the present disclosure. Electrical pulses  802 A- 802 I may be sequentially applied to separate electrodes  206  of the bottom layer. The processor  106  may instruct the display generator  104  to sequentially apply a series of electrical pulses  802  to the electrodes  206  of the respective resistive strips  402 T in the bottom layer. After a first electrical pulse  802 A is applied to a first electrode  206  in the bottom layer, the display generator  104  may wait for a predetermined amount of time to expire and may then apply a second electrical pulse  802 B to a second electrode  206 , and so forth until a pulse has been applied to each of the electrodes  206  in the bottom layer. Once an electrical pulse  802  has been applied to each electrode  206  in the bottom layer, the display generator  104  may return to the first electrode and may sequentially apply another round of electrical pulses  802  to each of the electrodes  206  in the bottom layer. The scanning frequency at which the pulses  802  are applied to a particular electrode  206  may depend on the number of resistive strips  402  of the bottom layer. In an example embodiment, each resistive strip may be scanned every 5 milliseconds. The resistive strips  402  also may be scanned more or less frequently. 
         [0033]    In an example,  FIG. 8  illustrates electrical pulse  802 A being applied to the uppermost electrode  206 , electrical pulse  802 B being applied to the next uppermost electrode  206 , and so forth until electrical pulse  802 I is applied to the last electrode  206 . Thereafter, the display generator  104  may repeat and sequentially apply the electrical pulses  802 A- 802 I another time. The electrical pulses  802 A- 802 I may be applied at unique times for use in determining which pair of resistive strips  402 , if any, has been contacted by a user. Similar electrical pulses (not shown) may be sequentially applied to each of the electrodes  206  of the top layer in the same manner as the pulses are described as being applied to the bottom layer in  FIG. 8 . 
         [0034]    When an electrical pulse  802  is being applied to a particular resistive strip  402  in a layer, the processor  106  may instruct the display generator  104  to sequentially measure the resistance between the resistive strip  402 T in the top layer and each of the resistive strips  402 B in the bottom layer. Once the resistance has been measured between the resistive strip  402 T in the top layer and each of the resistive strips  402 B in the bottom layer, the display generator  104  may move to the next resistive strip in the top layer and sequentially measure the resistance between that resistive strip in the top layer and each of the resistive strips in the bottom layer, until the resistance between each of the resistive strips in the top layer have been and each of the resistive strips in the bottom layer have been determined. Once completed, the processor  106  may instruct the display generator  104  to repeat the measuring process. 
         [0035]    In an example, referring again to  FIG. 6 , the processor  106  may instruct the display generator  104  to apply an electrical pulse  802  to electrode  206  to resistive strip  402 T in the top layer and to sequentially measure the resistance between the resistive strip  402 T and each of the resistive strips  402 B_ 1  to  402 B_ 5 . When measuring the resistance between resistive strip  402 T and resistive strip  402 B_ 1 , the display generator  104  may allow resistive strips  402 B_ 2  to  402 B_ 5  to float (i.e., be kept in a state of high resistance). To measure the resistance between resistive strip  402 T and resistive strip  402 B_ 2 , the display generator  104  may allow resistive strips  402 B_ 1  and  402 B_ 3  to  402 B_ 5  to float, and so forth. Floating the resistive strips  402  not being measured may reduce or eliminate current bypass issues. For example, if there is a touch between strip  402 T and  402 B_ 2  when measuring the resistance between resistive strip  402 T and resistive strip  402 B_ 1 , coupling resistive strip  402 B_ 2  to ground, for instance, would cause some electrical current to bypass resistive strip  402 T through the resistance between strip  402 T and  402 B_ 2 . Floating the resistive strips  402  not being measured (e.g., resistive strips  402 B_ 2  to  402 B_ 5  in this example) may reduce or eliminate this current bypass effect. 
         [0036]    Once measured, the processor  106  may respectively compare the resistance measurement for each pair of resistive strips  402  (e.g., the resistance between resistive strip  402 T and resistive strip  402 B_ 1 , the resistance between resistive strip  402 T and resistive strip  402 B_ 2 , etc.) to a stored resistance value for the pair. The stored resistance value may be a contactless resistance measurement between each pair of resistive strips  402 . 
         [0037]      FIG. 9  illustrates resistive strips  402  of the top and bottom layer of a tactile sensor  202  that have been contacted by a user in accordance with one or more example embodiments of the present disclosure. This figure illustrates the display screen  204  and a resistive strip  402 T of the top layer and a resistive strip  402 B of the bottom of the tactile sensor  202 , whereas the remaining resistive strips  402  have been omitted for clarity. When a user presses on a particular combination of resistive strips  402  of the tactile sensor  202 , such as at contact point  902 , the resistance characteristics of these resistive strips  402  may change, whereas the resistance characteristics of the other resistive strips that were not contacted may remain substantially the same. By sequentially applying the electrical pulses  802  to the electrodes  206  of the resistive strips  402 T and  402 B, the processor  106  can identify the resistive strip pair that the user contacted by measuring the resistance of pairs of resistive strips  402  and identifying the resistive strips where there has been a change in resistance due to contact (e.g., between resistive strips  402 T and  402 B at contact point  902 ). By identifying the pair of resistive strips  402  where the resistance has changed as compared with a stored resistance value, the user terminal  100  may determine the approximate location of the tactile input. The user terminal  100  may then determine coordinates (e.g., Cartesian coordinates) of the contact location  902  of the contacted resistive strip pair. 
         [0038]      FIG. 10  illustrates a measuring principle for determining coordinates of the contact point in accordance with one or more example embodiments of the present disclosure. The following discussing refers to both  FIGS. 9 and 10 . To determine a y coordinate along the y axis of  FIGS. 9 and 10 , the processor  106  may apply an electrical pulse  802  of voltage U 1  to create a voltage gradient across electrodes  206 B_ 1  and  206 B_ 2  and may measure a voltage U 2  at electrode  206 T_ 1 . The voltage U 2  may be measured at electrode  206 T_ 1  because of contact between the resistive strip  402 T in the top layer and the resistive strip  402 B in the bottom layer. Because each strip  402  is resistive, a resistive ratio of the resistive strip  402  along x axis or y axis may be constant. Based on the resistive ratio, the processor  106  may measure the voltage U 2  at electrode  206 T_ 1 , where 
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         [0039]    The voltage U 2  may represent the distance along the y axis of the user contact (i.e., a y coordinate) between electrodes  206 B_ 1  and  206 B_ 2 . Also, to determine an x coordinate along the x axis of  FIGS. 9 and 10 , the processor  106  may apply an electrical pulse  802  of voltage U 3  to create a voltage gradient across electrodes  206 T_ 1  and  206 T_ 2  and may measure a voltage U 4  at electrode  206 B_ 1 . The processor  106  may measure the voltage U 4  at electrode  206 B_ 1 , where 
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         [0040]    The voltage U 4  may represent the distance along the x axis of the user contact (i.e., the x coordinate) between electrodes  206 B_ 1  and  206 B_ 2 . The x and y coordinates on the multi-touch display screen  102  may also be determined using other methods. The processor  106  also may use conventional methods to measure touch force. 
         [0041]    Identifying pairs of resistive strips  402  where resistance has changed also may be used to process multiple simultaneous tactile inputs by a user. Because each of the resistive strips  402  in a layer are separated from one another by gap d and the manner in which the resistive strips  402  are scanned to measure resistance, the user terminal  100  may identify one or more pairs of resistive strips where there is a change in resistance as compared with a stored resistance value for the pair to identify one or more contact points (i.e., when there is not a touch, the pair of resistive strips may have a high or infinite resistance as there is no electrical contact). Then, the user terminal  100  may calculate the coordinates of each touch tactile input using the measuring principle discussed above with reference to  FIG. 10 . 
         [0042]    For instance, a user may contact the tactile sensor  202  at different locations at about the same time. The user terminal  100  may sequentially apply the electrical pulses  802  to the electrodes  206  to identify which pairs of resistive strips  402  have been contacted based on a change in resistance of the pair, and hence may identify different resistive strip pairs the user has contacted. Because the width of the resistive strip  402  can be less than or the same size as the touch point (e.g., a stylus or a finger), more than one tactile input may not be located on the same resistive strip pair. According to scanning method illustrated in  FIG. 8 , each pair of resistive strip pair having a change in contact resistance can be identified. Then according to method illustrated in  FIG. 10 , the user terminal  100  may calculate the coordinate of each touch tactile input. Thus, a resistive touch screen may be used to detect multiple simultaneous or near simultaneous tactile inputs from a user. 
         [0043]    Additionally, the processor  106  may use the determined coordinates to perform further processing. For example, the display generator  104  may display a plurality of icons on the display screen  204 . The processor  106  may compare the coordinates of the tactile input with the location at which each of the icons is displayed. The processor  106  may determine that the location of the tactile input is the user&#39;s selection of the icon closest to the tactile input or if the tactile input is within a certain distance from the icon, such as within a certain radius or selection area. The selection area may depend on the number of displayed icons. For instance, each icon may be associated with a rectangular area surrounding the area. The processor  106  may then execute a software program or other computer readable media that is associated with the closest icon or within the selection area. 
         [0044]    Further, the processor  106  may use the determined coordinate location as a handwriting input. The processor  106  may use the measuring principle for determining a sequence of coordinates discussed above in  FIG. 10  as the user provides tactile handwriting input. The processor  106  may process the handwriting input received at the tactile sensor  202  to identify a sequence of coordinates corresponding to the tactile handwriting input. 
         [0045]    In another example, the user terminal  100  may electrically connect together the electrodes  206  on the same side for each of the top and bottom layers. For instance, referring to  FIG. 4 , the user terminal  100  may electrically connect together the electrodes  206  depicted on the left into a first group, and may electrically connect together the electrodes  206  depicted on the right into a second group. Referring to  FIG. 5 , the user terminal  100  may electrically connect together the electrodes  206  depicted on the top into a third group, and may electrically connect together the electrodes  206  depicted on the bottom into a fourth group. The tactile sensor  202  may then detect handwriting as in conventional resistive single touch screen. For instance, the processor  106  may measure a voltage gradient across the top layer with the bottom layer acting as a return layer to measure a distance to the tactile input along the y axis and may measure a voltage gradient across the bottom layer with the top layer acting as a return layer to measure a distance to the tactile input along the x axis. 
         [0046]      FIG. 11  illustrates a flow diagram  1100  performed by the user terminal  100  in accordance with one or more example embodiments of the present disclosure. In block  1102 , the processor  106  of the user terminal  100  may instruct the display generator  104  to sequentially apply electrical pulses  802  to the electrodes  206  of the resistive strips  402  in a layer. For instance, the display generator  104  may sequentially apply electrical pulses  802  to each of the electrodes  206  of the resistive strips  402 T in the top layer while the resistive strips  402 B of the bottom layer not being measured can be floated. In another example, the display generator  104  may sequentially apply electrical pulses  802  to each of the electrodes  206  of the resistive strips  402 B of the bottom layer while the resistive strips  402 T of the top layer not being measured are floated. Once an electrical pulse  802  has been applied to the electrodes  206  for each of the resistive strips in either the top or bottom layer, the display generator  104  may return to the electrodes  206  of the first resistive strip  402  in the layer and may sequentially apply the electrical pulses another round of electrical pulses  802 . 
         [0047]    In block  1104 , the processor  106  of the user terminal  100  may instruct the display generator  104  to sequentially measure the resistance between resistive strip pairs from the top and bottom layers to identify whether any pairs exhibit a change in resistance. In an example, when an electrical pulse  802  is being applied to a particular resistive strip  402 T in the top layer, the display generator  104  may measure the resistance between particular resistive strip  402 T and each of the resistive strips  402 B in the bottom layer. A resistive measurement may be made as the electrical pulses  802  are sequentially applied to the different resistive strips  402  to measure the resistance between all combinations of resistive strips  402 T in the top layer and resistive strips  402 B in the bottom layer. 
         [0048]    In block  1106 , the processor  106  may determine whether any resistance changes have been detected for any pairs of resistive strips  402 . For instance, the processor  106  may access resistance values stored in memory  108  for each resistive strip pair and may compare the measured resistance to the stored resistance for each pair to identify any changes. The stored resistance values may be based on a contactless resistance measurement between each of the resistive strip pairs. The processor  106  may detect that a particular resistive strip pair is being contacted by a user if there is a change in the resistance when compared with the contactless resistance measurement. If no change in resistance is detected for any of the resistive strip pairs, the flow diagram  1100  may return to block  1102 . If any change in resistance is detected for one or more resistive strip pairs, the flow diagram  1100  may continue to block  1108 . 
         [0049]    In block  1108 , the processor  106  may determine the coordinates of the tactile input on the one or more resistive strip pairs experiencing the change in resistance. The processor  106  may determine the coordinates (e.g., Cartesian coordinates) using the measuring principle discussed above with reference to  FIG. 10 . The processor  106  may use the coordinates to perform further processing. For instance, the processor  106  may determine that the user selected a displayed icon closest to the Cartesian coordinates or may interpret the input as handwriting of the user. The processor  106  may then execute a software program associated with the closest icon. The flow diagram  1100  may then return to block  1102 . 
         [0050]    Accordingly, some example embodiments of the present disclosure incorporate resistive touch screen technology to implement a multi-touch display screen. These example embodiments may advantageously avoid expensive manufacturing techniques and do not involve complex signal processing methods or complex processing circuitry. The multi touch screen in accordance with some example embodiments of the present disclosure is able to process handwriting input by a user using resistive touch screen technology. 
         [0051]    The foregoing description was provided with respect to processing multiple user input by using resistive screen technology. It is understood that the principles described herein may be extended to any device that displays information to a user and requests tactile user input. 
         [0052]    Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.