Touch panel system and method for distinguishing multiple touch inputs

Abstract

Touch panel systems and methods are disclosed that can distinguish temporally overlapping touch inputs from single touch inputs so that valid touch position coordinates can be determined. Touch panel systems and methods of the present invention can distinguish overlapping touches by comparing signal magnitudes to specified thresholds, by comparing the rates of change of signal magnitudes or measured positions to determined parameters, by locating the proximity a calculated location to icons or other such active areas, and the like. Because touch panel systems and methods of the present invention can discriminate single touches from double touches, they can be used in multiple user applications such as multiplayer games as well as in applications that may be subject to rapidly successive or overlapping touch inputs.

1 . A touch screen system comprising: 
 a touch panel for measuring touch-based user input signals;    an information display disposed for viewing through the touch panel; and    a processing unit for discriminating the touch-based user input signals to determine which signals correspond to temporally overlapping individual touch inputs by comparing a signal magnitude to one or more predetermined threshold values and by performing one or more of monitoring a signal magnitude rate of change, monitoring a rate of change of calculated touch position, monitoring proximity of touch position to one or more designated active areas, or monitoring proximity of touch position to one or more designated regions of higher double touch probability.    
   
   
       2 . The touch system of  claim 1 , wherein the touch panel is a capacitive touch panel.  
   
   
       3 . The touch system of  claim 1 , wherein the touch panel is a resistive touch panel.  
   
   
       4 . The touch system of  claim 1 , wherein the touch panel is a force-based touch panel.  
   
   
       5 . The touch system of  claim 1 , wherein the touch panel is a surface acoustic wave touch panel.  
   
   
       6 . The touch system of  claim 1 , wherein the touch system is part of a game system that allows at least two players to use the touch panel.  
   
   
       7 . A method for distinguishing temporally overlapping touch inputs in a touch screen system comprising: 
 repeatedly measuring a signal caused by one or more touch inputs;    monitoring rates of change of the signal;    correlating the rates of change of the signal with touch-down, hold, and lift-off events, to determine a sequence of said events;    using the determined sequence of said events to determine a temporal ordering of the one or more touches;    calculating a touch location of at least one of the one or more touches given the determined sequence; and    reporting the touch location.    
   
   
       8 . The method of  claim 7 , further comprising the step of determining that said touch location resides in an area of the touch screen designated as an active area.  
   
   
       9 . The method of  claim 8 , wherein the active area corresponds to a displayed icon.  
   
   
       10 . The method of  claim 7 , wherein the step of reporting said touch location is not performed for a calculated touch location if said touch location has moved more than a predetermined distance from a preceding calculated touch location.  
   
   
       11 . The method of  claim 7 , further comprising the step of comparing a magnitude of the signal to a minimum threshold value and a maximum threshold value so that the reporting step is only performed for touch locations that correspond to signals whose magnitude exceeds the minimum threshold but does not exceed the maximum threshold.  
   
   
       12 . A method for distinguishing valid touch inputs among temporally overlapping touch inputs in a touch screen system comprising: 
 measuring a predetermined number of touch signals, each measurement taken at a predetermined time interval, each time interval being shorter than an expected touch input hold duration;    calculating a signal parameter for each of the signals;    calculating a touch location for each of the signals that is within a predetermined range; and    reporting a touch position to the touch screen system for any of the calculated touch locations that is less than a predetermined distance away from any of the other calculated touch locations.    
   
   
       13 . The method of  claim 12 , further comprising the step of determining that said touch location resides in an area of the touch screen designated as an active area.  
   
   
       14 . The method of  claim 13 , wherein the active area corresponds to a displayed icon.  
   
   
       15 . A method for distinguishing valid touch inputs among temporally overlapping touch inputs in a touch screen system comprising: 
 measuring a predetermined number of touch signals, each measurement taken at a predetermined time interval, each time interval being shorter than an expected touch input hold duration;    determining a signal parameter for each of the signals;    calculating a touch location for each of the signal parameters that is within a predetermined range;    adjusting the predetermined range and repeating the calculating step for any touch location that is within a designated region corresponding to a higher probability of double touch events; and    reporting a touch position to the touch screen system for the calculated touch locations.    
   
   
       16 . A method for distinguishing valid touch inputs among temporally overlapping touch inputs in a touch screen system comprising: 
 determining a total signal from a set of measured touch signals;    calculating a touch position from the set of measured touch signals when the total signal exceeds a minimum threshold value;    performing one or both of 
 (a) setting a test parameter for rate of change of total signal magnitude based on where the calculated touch position is located, and comparing the total signal magnitude to other recently measured total signal magnitudes to determine whether the test parameter for rate of change of total signal magnitude is satisfied,  
 (b) setting a test parameter for rate of change of position based on where the calculated touch position is located, and comparing the touch position to other recently measured positions to determine whether the test parameter for rate of change of position is satisfied; and  
   when the applicable test parameter or test parameters is satisfied, reporting the touch position when the total signal does not exceed a maximum threshold.    
   
   
       17 . The method of  claim 16 , wherein the maximum threshold is set based on location of the touch position.  
   
   
       18 . The method of  claim 16 , wherein the touch position is reported only if the touch position corresponds to an designated active area.  
   
   
       19 . A method for distinguishing valid touch inputs among temporally overlapping touch inputs in a touch screen system comprising: 
 measuring a predetermined number of touch signals, each measurement taken at predetermined time intervals, the time intervals being shorter than an expected touch input hold duration;    associating a signal parameter with each of the signals;    calculating a touch location for each of the signals whose associated parameter is above a minimum threshold but below a maximum threshold; and    reporting a touch position to the touch screen system for any of the touch locations calculated in the calculating step.    
   
   
       20 . The method of  claim 19 , wherein the signal parameter is a total signal magnitude.  
   
   
       21 . The method of  claim 19 , wherein the signal parameter is a signal magnitude rate of change.  
   
   
       22 . The method of  claim 19 , wherein the signal parameter is a rate of change of position.  
   
   
       23 . The method of  claim 19 , wherein the signal parameter is proximity to an icon placement.  
   
   
       24 . A method for distinguishing phantom touch positions from valid touch positions during a double touch event in a touch screen system comprising: 
 independently measuring an X-coordinate position for each touch in the double touch;    independently measuring a Y-coordinate position for each touch in the double touch;    determining a rate of change of magnitude of a measured signal corresponding to each X-coordinate position and each Y-coordinate position;    matching X-coordinate positions with Y-coordinate positions based on similar rates of change; and    reporting the matched X, Y coordinates as the valid touch positions.