Abstract:
A method for detecting and tracking a single finger or multi-finger gesture referred to as an edge swipe gesture that originates from an edge of a touch sensor and which is distinguished from normal touch sensor operations such as cursoring, wherein the edge swipe gesture generates detection and tracking data having an immediate change, whereas touchdown or movement towards and then away from an edge of the touch sensor will generate data that is different from the edge swipe gesture.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to touch sensor technology. More specifically, the present invention is a system for distinguishing single and/or multiple finger swipes or actions upon entering a touch-surface area from the touch-surface edges to activate specific gestures or commands, as compared to normal cursoring or gesturing directly on the touch-surface. 
     2. Description of Related Art 
     There are several designs for capacitance sensitive touchpads. It is useful to examine the underlying technology to better understand how any capacitance sensitive touchpad can be modified to work with the present invention. 
     The CIRQUE® Corporation touchpad is a mutual capacitance-sensing device and an example is illustrated as a block diagram in  FIG. 1 . In this touchpad  10 , a grid of X ( 12 ) and Y ( 14 ) electrodes and a sense electrode  16  is used to define the touch-sensitive area  18  of the touchpad. Typically, the touchpad  10  is a rectangular grid of approximately 16 by 12 electrodes, or 8 by 6 electrodes when there are space constraints. Interlaced with these X ( 12 ) and Y ( 14 ) (or row and column) electrodes is a single sense electrode  16 . All position measurements are made through the sense electrode  16 . 
     The CIRQUE® Corporation touchpad  10  measures an imbalance in electrical charge on the sense line  16 . When no pointing object is on or in proximity to the touchpad  10 , the touchpad circuitry  20  is in a balanced state, and there is no charge imbalance on the sense line  16 . When a pointing object creates imbalance because of capacitive coupling when the object approaches or touches a touch surface (the sensing area  18  of the touchpad  10 ), a change in capacitance occurs on the electrodes  12 ,  14 . What is measured is the change in capacitance, but not the absolute capacitance value on the electrodes  12 ,  14 . The touchpad  10  determines the change in capacitance by measuring the amount of charge that must be injected onto the sense line  16  to reestablish or regain balance of charge on the sense line. 
     The system above is utilized to determine the position of a finger on or in proximity to a touchpad  10  as follows. This example describes row electrodes  12 , and is repeated in the same manner for the column electrodes  14 . The values obtained from the row and column electrode measurements determine an intersection which is the centroid of the pointing object on or in proximity to the touchpad  10 . 
     In the first step, a first set of row electrodes  12  are driven with a first signal from P, N generator  22 , and a different but adjacent second set of row electrodes are driven with a second signal from the P, N generator. The touchpad circuitry  20  obtains a value from the sense line  16  using a mutual capacitance measuring device  26  that indicates which row electrode is closest to the pointing object. However, the touchpad circuitry  20  under the control of some microcontroller  28  cannot yet determine on which side of the row electrode the pointing object is located, nor can the touchpad circuitry  20  determine just how far the pointing object is located away from the electrode. Thus, the system shifts by one electrode the group of electrodes  12  to be driven. In other words, the electrode on one side of the group is added, while the electrode on the opposite side of the group is no longer driven. The new group is then driven by the P, N generator  22  and a second measurement of the sense line  16  is taken. 
     From these two measurements, it is possible to determine on which side of the row electrode the pointing object is located, and how far away. Pointing object position determination is then performed by using an equation that compares the magnitude of the two signals measured. 
     The sensitivity or resolution of the CIRQUE® Corporation touchpad is much higher than the 16 by 12 grid of row and column electrodes implies. The resolution is typically on the order of 960 counts per inch, or greater. The exact resolution is determined by the sensitivity of the components, the spacing between the electrodes  12 ,  14  on the same rows and columns, and other factors that are not material to the present invention. 
     The process above is repeated for the Y or column electrodes  14  using a P, N generator  24   
     Although the CIRQUE® touchpad described above uses a grid of X and Y electrodes  12 ,  14  and a separate and single sense electrode  16 , the sense electrode can actually be the X or Y electrodes  12 ,  14  by using multiplexing. 
     Having described a touchpad that can be modified to operation with the principles of the present invention, it is useful to understand that there are systems that already teach the recognition of a finger swipe or multiple finger swipes that enter a touch surface from the edge of a touchpad. However, some of these systems are not perfect in the manner in which they distinguish between a typical cursoring function and the gesture being performed. Accordingly, it would be an improvement to teach a new system and method for detecting and tracking movement of a finger or fingers on a capacitance sensitive touchpad. 
     BRIEF SUMMARY OF THE INVENTION 
     In a preferred embodiment, the present invention is a method for detecting and tracking a single finger or multi-finger gesture referred to as an edge swipe gesture that originates from an edge of a touch sensor and which is distinguished from normal touch sensor operations such as cursoring, wherein the edge swipe gesture generates detection and tracking data having an immediate change, whereas touchdown or movement towards and then away from an edge of the touch sensor will generate data that is different from the edge swipe gesture. 
     These and other objects, features, advantages and alternative aspects of the present invention will become apparent to those skilled in the art from a consideration of the following detailed description taken in combination with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a block diagram of the components of a capacitance-sensitive touchpad as made by CIRQUE® Corporation and which can be operated in accordance with the principles of the present invention. 
         FIG. 2  is a top view of a touch sensor that demonstrates that a finger has made touchdown on the touch sensor and that an edge swipe gesture has not been performed. 
         FIG. 3  is a graph that illustrates finger detection and position tracking data that shows that the finger paused before movement, and is therefore not an edge swipe gesture. 
         FIG. 4  is a top view of a touch sensor that demonstrates that a finger has made touchdown on the touch sensor in a normal zone, moved to the boundary zone, and then back to the normal zone, and is not interpreted as an edge swipe gesture. 
         FIG. 5  is a top view of a touch sensor that demonstrates that a finger has made touchdown outside the touch sensor, and then moves onto the touch sensor to make an edge swipe gesture. 
         FIG. 6  is a graph that illustrates finger detection and position tracking data that shows that the finger was moving immediately upon entering the touch sensor and is therefore characterized as an edge swipe gesture. 
         FIG. 7  is a top view of a touch sensor that demonstrates that a finger has made touchdown outside the touch sensor, and then moves onto the touch sensor very rapidly to make an edge swipe gesture which is recognized by dynamically moving an edge of the boundary zone. 
         FIG. 8  is a graph that illustrates finger detection and position tracking data that shows that the finger was moving immediately upon entering the touch sensor and is therefore characterized as an edge swipe gesture, the finger characterized as being farther into the touch sensor when detected and having a steeper slope. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made to the drawings in which the various elements of the present invention will be given numerical designations and in which the invention will be discussed so as to enable one skilled in the art to make and use the invention. It is to be understood that the following description is only exemplary of the principles of the present invention, and should not be viewed as narrowing the claims which follow. It should also be understood that the terms “touchpad”, “touchscreen”, “touch sensor”, “touch input device” and “touch sensitive device” may be used interchangeably throughout this document. 
     The first embodiment of the present invention is a new system and method for distinguishing between a typical cursoring or gesture function that is being performed by one or more fingers (also referred to as pointing objects) on a touch sensor, and a gesture that is characterized by swiping onto a touch sensor from any surrounding edge. 
     The position data produced when swiping a finger from the edge of a touch sensor and toward the middle of the touch sensor may produce ambiguous position data regarding the action being performed. The position data may indicate that either normal cursoring should be performed or an edge action gesture should be performed. The ambiguous position data may be generated from one or multiple fingers that enter the touch sensor from the edge. 
     For example, consider  FIG. 2 .  FIG. 2  is a top view of a touch sensor  30 . The touch sensor  30  may or may not include one or more dedicated buttons  32  associated with the touch sensor. These dedicated buttons  32  are not relevant to the present invention but are shown for illustration purposes only. 
     A line  34  is shown on the touch sensor  30  that is an indication of a boundary zone  36  around the touch sensor that is an indication of an outer edge boundary. The width of the boundary zone  36  may be changed as desired, and is not a limitation of the present invention. 
     The location  38  that is represented by a circle is indicative of a touchdown by a pointing object such as a finger.  FIG. 3  is provided as a graph of position detection and tracking data. The Y axis is indicative of position along an X axis of the touch sensor  30 . It should be understood that the position information may show movement along any axis of the touch sensor  30 , and the position being shown is for illustration purposes only. The X axis of the graph is time, as represented by counts. What is important is that a straight line is indicative of no movement of a finger, and a slope, up or down, is indicative of movement of the finger. 
     In this example,  FIG. 3  shows touchdown using arrow  40 . The oval  42  surrounds a portion of the line that is level or a plateau that is indicative of a period of time where there is substantially no movement of the finger. In the first embodiment of the present invention, what appears to be a touchdown  38  followed immediately by a lack of movement  42  is an indication that a finger made touchdown and then moved. The present invention may interpret the behavior of the finger as represented by the position detection and tracking data shown in the graph of  FIG. 3  to indicate that an edge swipe gesture was not performed, but rather a cursoring function. 
       FIG. 4  is an illustration of a top view of the touch sensor  30 . Touchdown occurs as indicated by arrow  38  in a normal zone  44 . The finger moves from a location on the touch sensor  30  is in the normal zone  44 , then moves to the boundary zone  36 , and then back into the normal zone. This action is also not interpreted as indicative of an edge swipe gesture. 
       FIG. 5  is a top view of the touch sensor  30 , the buttons  32 , a boundary zone  36  and a normal zone  44  separated by a line  34 . In the first embodiment of the present invention, a swipe that is initiated from off of the touch sensor will produce a different set of finger (or fingers) position detection and tracking data as compared to a finger touchdown on the touch sensor followed by a swipe as shown in  FIGS. 2 and 3 . Touchdown is shown as having occurred off the touch sensor  30  at location  46 . The finger is then shown as moving on to the touch sensor, through the boundary zone  36  and into the normal zone  44 . 
       FIG. 6  is a graphical representation of finger position detection and tracking data for the finger shown in  FIG. 5 . A finger moving onto the touch sensor  30  from any location off the touch sensor may produce a graph showing a constant upward or downward slope in finger position detection and tracking data when an edge swipe gesture is initiated from off the touch sensor. 
     In this example, there is no leveling of the line. The absence of a level line, and thus the presence of an upward (or downward) slope as indicated by oval  48 , may indicate that the finger is moving the moment that it moves on to the surface of the touch sensor  30 , and for at least some period of time after. This behavior may be interpreted to be an indication of an edge swipe gesture. 
     It should be understood that the finger could move onto the touch sensor  30  from any of the edges, and not just from the left edge as shown in  FIG. 5 . Furthermore, the graph shown in  FIG. 6  could also be indicative of an edge swipe gesture from any of the edges of the touch sensor  30 . The upward slope shown in oval  48  may also be represented by a downward slope which would simple mean movement in an opposite direction if the finger entered the touch sensor  30  from a right edge. 
     It should also be understood that the Y axis of the graph could also be representative of movement along the Y axis of the touch sensor  30  and not the X axis if the finger were to move onto the touch sensor  30  from the top edge or the bottom edge. 
     It is also noted that the first indication that a finger has been detected is shown by the arrow  50  in  FIG. 6 . This portion of the finger position detection and tracking data is indicative of the presence of the finger being sensed before it is moved onto the touch sensor  30 . Likewise, in  FIG. 3 , the portion of the line indicated by arrow  50  also shows that the presence of the finger can be detected as it is lowered onto the touch sensor  30  from above before touchdown occurs. 
     Three observations can be made from graphical representation of finger position and tracking data in  FIG. 6 . First, the finger or fingers will not appear motionless at the point in time that the finger is moving onto the touch sensor  30 . 
     The second observation is that the edge swipe gesture may be a very short-lived event in time. In other words, very little movement of a finger is needed to show that the edge swipe gesture has been initiated. Thus, movement may also quickly come to a halt as indicated by a leveling of the line. The edge swipe gesture may then be interrupted by removal of the finger from the touch sensor  30 , or movement may begin again. 
     A third observation is that an upward slope is generated in position data when a finger enters the touch sensor from a first side, and a downward slope is generated when the finger enters from an opposite or second side of the touch sensor. It is not important which side shows an upward slope and which side shows a downward slope. What is important is that the slope exists because that indicates movement of a finger from an edge onto the touch sensor  30 . 
     In another aspect of the invention, if the slope is in one direction when the finger is moving, reversing the direction of the finger may result in a reversal of the direction of the slope. Nevertheless, this reversal of direction may also be recognized as part of the edge swipe gesture. 
     What is important for recognition of an edge swipe gesture is that the slope exists for at least some minimum distance so that the movement can be classified as a “constant” slope up or down, and that the slope begins immediately when it is being tracked by the touch sensor  30 . In other words, there should be no initial level period. 
     Another observation regarding the first embodiment is that it shows that it is possible to quickly reject finger position detection and tracking data that does not show a valid edge swipe gesture and determine that the movement being detected is a cursoring or other function because the level line is an indicator of a pause at touchdown. 
     The first embodiment of the present invention describes the ability to distinguish between a single or multi-finger edge swipe gesture, and alternative scenarios such as the finger beginning at the inside edge of the touch sensor, or cursoring over to the boundary zone  36  of the touch sensor  30  and then moving back away from an edge with a single or multiple fingers. Accordingly, the first embodiment includes the ability to distinguish edge swipe gestures that are performed with single or multiple fingers. 
     In another embodiment of the present invention, a different aspect of the invention relates to the speed with which a finger is entering the touch sensor  30 . Consider the touch sensor  30  shown in  FIG. 7 .  FIG. 7  shows the normal left edge  52  of the boundary zone  36 . In this alternative embodiment of the invention, if the finger makes touchdown at location  38  but moves so quickly through the boundary zone  36  such that in a next sample of position it has already moved into the normal zone  44 , it may be necessary to make the edges of the boundary zone  36  to be dynamically changeable. For example, the left edge  52  of the boundary zone  36  might be moved to dotted line  54 . The change in position of the left edge  52  is only temporary and may revert to its original position once the edge swipe gesture is complete. What is important is that the edge swipe gesture not be unrecognized simply because the finger or fingers moved onto the touch sensor  30  so rapidly that position data was not keeping up with the rate of movement. Temporary movement of any of the edges of the touch sensor  30  may be possible when needed. 
     Another way to examine this alternative embodiment is to examine the finger position detection and tracking data that may be used to generate a graph.  FIG. 6  was used to recognize an edge swipe gesture. 
       FIG. 8  is a graph that illustrates the concept that a more rapid movement of a finger onto the touch sensor  30  may be represented by a line  56  having two characteristics. The first characteristic is a line that starts much higher on the Y axis. The Y axis is representative of an absolute position. Thus, because the finger has moved so rapidly, a first detected position may be further into the touch sensor  30  than a slower moving finger, which may be represented as higher up on the Y axis. 
     The second characteristic that the line  56  for a rapidly moving finger may have a steeper slope, either up or down, as shown in  FIG. 8 . 
     In another aspect of the invention, various position characteristics of the detected finger may be used alone or in combination in order to analyze the movement of the finger to determine if an edge swipe gesture is being performed. These position characteristics include, but should not be considered as limited to, constant slope after detection, degree of slope, and initial position of the pointing object. 
     In another aspect of the invention, an edge swipe gesture may not only have to have immediate movement upon entering the touch sensor  30 , but there may also be a requirement for movement of a threshold distance onto the touch sensor  30 . 
     It is noted that the same finger detection and position tracking data may be gathered for multiple fingers simultaneously. 
     The edge swipe gesture may be any gesture function that is known to those skilled in the art. The present invention is not limited by the specific function being activated by the edge swipe gesture. The present invention addresses how to recognize an edge swipe gesture and how to distinguish it from finger movements that are not edge swiping gestures. 
     It is to be understood that the above-described arrangements are only illustrative of the principles of the present invention. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the spirit and scope of the present invention. The appended claims are intended to cover such modifications and arrangements.