Abstract:
A system and method for detecting and tracking multiple objects on a touchpad or touchscreen, wherein the method provides a new data collection algorithm, wherein the method reduces a calculation burden on a processor performing detection and tracking algorithms, wherein multiple objects are treated as elements of a single object and not as separate objects, wherein the location of the objects are treated as end-points of a single object when two objects are detected, and treated as a perimeter or boundary when more than two objects are detected.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This document claims priority to and incorporates by reference all of the subject matter included in the non-provisional patent application docket number 4086.CIRQ.NP, having Ser. No. 12/268,338, filed on Nov. 10, 2008, and issuing as U.S. Pat. No. 8,284,166 on Oct. 9, 2012. 
     
    
     FIELD OF THE INVENTION  
       [0002]    This invention relates generally to methods of providing input to a touchpad. Specifically, the invention relates to a method of detecting and tracking multiple objects on a touch sensitive surface by treating the multiple objects as a single object whose perimeter or end-points are defined by the multiple objects, thereby treating the multiple objects as a single object in order to simplify detection and tracking algorithms. 
       DESCRIPTION OF RELATED ART  
       [0003]    As portable electronic appliances become more ubiquitous, the need to efficiently control them is becoming increasingly important. The wide array of portable electronic devices that can benefit from using a touch sensitive surface as a means of providing user input include, but should not be considered limited to, music players, DVD players, video file players, personal digital assistants (PDAs), digital cameras and camcorders, mobile telephones, laptop and notebook computers, global positioning satellite (GPS) devices and other portable electronic devices. Even stationary electronic appliances such as desktop computers can take advantage of an improved system and method of providing input to a touchpad that provides greater functionality to the user. 
         [0004]    One of the main problems that many portable and stationary electronic appliances have is that their physical dimensions limit the number of ways in which communicating with the appliances is possible. There is typically a very limited amount of space that is available for an interface when portability is an important feature. For example, mobile telephones often referred to as smart phones are now providing the functions of a telephone and a personal digital assistant (PDA). Typically, PDAs require a significant amount of surface area for input and a display screen to be practical. 
         [0005]    A recent entry to the mobile telephone market provides an LCD having touch sensitive screen capabilities. With a finite amount of space available for a display screen space because the smart phone is portable, a means was created for expanding and shrinking the relative size of the data being displayed. More specifically, consider a page of data that if displayed at a more conventional resolution would fill a page that is approximately the size of a normal sheet of paper. The entire page of data can be shown on the display screen but in a significantly reduced size because the physical dimensions of the display screen are small compared to the size of the typical sheet of paper. The problem was how to display the data on the page at a size that was usable. The solution was to magnify smaller portions of the page. Thus, only a portion of the whole page could be viewed at any one time. The effect was to zoom in or magnify portions of the page. The tradeoff is that the entire page cannot be viewed at the same time. Accordingly, the user must move or “drag” the data on the page so that different portions of the page are revealed. 
         [0006]    Thus, consider an entire web page being displayed so that the entire screen is visible, but the physical size of the display screen is only a matter of inches on each side. The data on the page is typically illegible at such a small size. A user will select a portion of the page to be magnified. As the data on the page grows larger and larger, the outer edges of the page essentially disappear beyond the borders of the display screen. The user then drags a finger on the display screen, thereby changing what portion of the page is visible on the display screen. Accordingly, previously hidden portions of the page become visible as other portions become hidden. 
         [0007]    One motion that can be performed on a touch sensitive surface such as touchscreen or touchpad to perform zooming in and out of a page is a pinching motion or its reverse. For example, to perform a zoom operation to magnify the page, a user brings a thumb and forefinger together until they are touching, then places the thumb and finger down on the touch sensitive surface so that a side of the thumb and finger make contact with the touch sensitive surface. The user then essentially spreads the thumb and forefinger apart from each other while maintaining contact with the touch sensitive surface. The magnification of the page on the display screen increases as long as the thumb and forefinger continue to move apart. Similarly, the magnification of the page on the display screen is reversed by simply pinching the thumb and forefinger together while maintaining contact with the touch sensitive surface. The user can make this pinching and reverse pinching and motion repeatedly, thereby causing the page to zoom in or out as the magnification increases or decreases. 
         [0008]    Disadvantageously, one method that is well known in the prior for performing the detection and tracking of the thumb and forefinger on the touchpad surface is to detect and track the thumb and forefinger (or whichever digits are being used to pinch and reverse pinch) as separate objects on the touch sensitive surface. Tracking multiple objects means that the calculations that are performed for one object must be performed for each object. Thus, the calculation burden on any touchpad processor increases substantially for each finger or pointing object (hereinafter used interchangeably) that is being tracked. 
         [0009]    It would be an improvement over the prior art to simplify the process of detecting and tracking multiple objects on a touch sensitive surface such as a touchpad or a touchscreen (referred to hereinafter as a touchpad). It would be an improvement over the prior art to simplify the process of detection and tracking of multiple objects on a touch sensitive surface such as a touchpad or a touchscreen. 
         [0010]    It is useful to describe one embodiment of touchpad and touchscreen technology that can be used in the present invention. Specifically, the capacitance-sensitive touchpad and touchscreen technology of CIRQUE® Corporation can be used to implement the present invention. The CIRQUE® Corporation touchpad is a mutual capacitance-sensing device and an example is illustrated in  FIG. 1 . The touchpad can be implemented using an opaque surface or using a transparent surface. Thus, the touchpad can be operated as a conventional touchpad or as a touch sensitive surface on a display screen, and thus as a touch screen. 
         [0011]    In this touchpad technology of Cirque® Corporation, a grid of row and column electrodes is used to define the touch-sensitive area of the touchpad. Typically, the touchpad is a rectangular grid of approximately 16 by 12 electrodes, or 8 by 6 electrodes when there are space constraints. Interlaced with these row and column electrodes is a single sense electrode. All position measurements are made through the sense electrode. However, the row and column electrodes can also act as the sense electrode, so the important aspect is that at least one electrode is driving a signal, and another electrode is used for detection of a signal. 
         [0012]    In more detail,  FIG. 1  shows a capacitance sensitive touchpad  10  as taught by CIRQUE® Corporation includes a grid of row (12) and column (14) (or X and Y) electrodes in a touchpad electrode grid. All measurements of touchpad parameters are taken from a single sense electrode  16  also disposed on the touchpad electrode grid, and not from the X or Y electrodes  12 ,  14 . No fixed reference point is used for measurements. Touchpad sensor control circuitry  20  generates signals from P, N generators  22 ,  24  (positive and negative) that are sent directly to the X and Y electrodes  12 ,  14  in various patterns. Accordingly, there is typically a one-to-one correspondence between the number of electrodes on the touchpad electrode grid, and the number of drive pins on the touchpad sensor control circuitry  20 . However, this arrangement can be modified using multiplexing of electrodes. 
         [0013]    The touchpad  10  does not depend upon an absolute capacitive measurement to determine the location of a finger (or other capacitive object) on the touchpad surface. The touchpad  10  measures an imbalance in electrical charge to the sense line  16 . When no pointing object is on the touchpad  10 , the touchpad sensor control circuitry  20  is in a balanced state, and there is no signal on the sense line  16 . There may or may not be a capacitive charge on the electrodes  12 ,  14 . In the methodology of CIRQUE® Corporation, that is irrelevant. When a pointing device creates imbalance because of capacitive coupling, a change in capacitance occurs on the plurality of electrodes  12 ,  14  that comprise the touchpad electrode grid. What is measured is the change in capacitance, and 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 on the sense line. 
         [0014]    The touchpad  10  must make two complete measurement cycles for the X electrodes  12  and for the Y electrodes  14  (four complete measurements) in order to determine the position of a pointing object such as a finger. The steps are as follows for both the X  12  and the Y  14  electrodes: 
         [0015]    First, a group of electrodes (say a select group of the X electrodes  12 ) are driven with a first signal from P, N generator  22  and a first measurement using mutual capacitance measurement device  26  is taken to determine the location of the largest signal. However, it is not possible from this one measurement to know whether the finger is on one side or the other of the closest electrode to the largest signal. 
         [0016]    Next, shifting by one electrode to one side of the closest electrode, the group of electrodes is again driven with a signal. In other words, the electrode immediately to the one side of the group is added, while the electrode on the opposite side of the original group is no longer driven. 
         [0017]    Third, the new group of electrodes is driven and a second measurement is taken. 
         [0018]    Finally, using an equation that compares the magnitude of the two signals measured, the location of the finger is determined. 
         [0019]    Accordingly, the touchpad  10  measures a change in capacitance in order to determine the location of a finger. All of this hardware and the methodology described above assume that the touchpad sensor control circuitry  20  is directly driving the electrodes  12 ,  14  of the touchpad  10 . Thus, for a typical 12×16 electrode grid touchpad, there are a total of 28 pins (12+16=28) available from the touchpad sensor control circuitry  20  that are used to drive the electrodes  12 ,  14  of the electrode grid. 
         [0020]    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 on the same rows and columns, and other factors that are not material to the present invention. 
         [0021]    Although the CIRQUE® touchpad described above uses a grid of X and Y electrodes and a separate and single sense electrode, the sense electrode can also be the X or Y electrodes by using multiplexing. Either design will enable the present invention to function. 
         [0022]    The underlying technology for the CIRQUE® Corporation touchpad is based on capacitive sensors. However, other touchpad technologies can also be used for the present invention. These other proximity-sensitive and touch-sensitive touchpad technologies include electromagnetic, inductive, pressure sensing, electrostatic, ultrasonic, optical, resistive membrane, semi-conductive membrane or other finger or stylus-responsive technology. 
         [0023]    The prior art includes a description of a touchpad that is already capable of the detection and tracking of multiple objects on a touchpad. This prior art patent teaches and claims that the touchpad detects and tracks individual objects anywhere on the touchpad. The patent describes a system whereby objects appear as a “maxima” on a signal graphed as a curve that indicates the presence and location of pointing objects. Consequently, there is also a “minima” which is a low segment on the signal graph which indicates that no pointing object is being detected. 
         [0024]      FIG. 2  is a graph illustrating the concept of a first maxima  30 , a minima  32  and a second maxima  34  that is the result of the detection of two objects with a gap between them on a touchpad. 
         [0025]    The prior art is always tracking the objects as separate and individual objects, and consequently must follow each object as it moves around the touchpad. 
         [0026]    It would be an advantage over the prior art to provide a new detection and tracking method that does not require the system to determine how many objects are on the touchpad surface, and yet still be capable of being aware of their presence. 
       BRIEF SUMMARY OF THE INVENTION 
       [0027]    In a preferred embodiment, the present invention is a system and method for detecting and tracking multiple objects on a touchpad or touchscreen, wherein the method provides a new data collection algorithm, wherein the method reduces a calculation burden on a processor performing detection and tracking algorithms, wherein multiple objects are treated as elements of a single object and not as separate objects, wherein the location of the objects are treated as end-points of a single object when two objects are detected, and treated as a perimeter or boundary when more than two objects are detected. 
         [0028]    In a first aspect of the invention, existing touchpad and touchscreen (hereinafter referred to collectively as “touchpad”) hardware and scanning routines can be used with this new analysis algorithm. 
         [0029]    In a second aspect of the invention, the new analysis algorithm can be implemented in firmware without hardware changes. 
         [0030]    In a third aspect, a touchpad performs a normal scanning procedure to obtain data from all the electrodes on the touchpad, wherein the data is analyzed by looking for an object by starting at an outer edge or boundary of touchpad and then moving inwards. Data analysis ends when the edge of an object is detected in the data. Analysis then begins on the outer edge or boundary opposite the first outer edge, and then continuing inwards. Again, data analysis ends when the edge of an object is detected in the data. The process is then repeated in the orthogonal dimension. Thus if the first boundaries are both horizontal boundaries of the touchpad, then analysis begins using both of the vertical boundaries. Analysis never shows what is detected on the touchpad past the edge of the first object from each direction. Thus, the touchpad never determines the total number of objects on the touchpad, and never has to calculate anything but the edge of objects from four directions, thereby substantially decreasing the calculation overhead on a touchpad processor. 
         [0031]    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 
         [0032]      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. 
           [0033]      FIG. 2  is a graph showing the detection of two objects on a touchpad as taught by the prior art. 
           [0034]      FIG. 3  is a top view of a touchpad of the present invention showing a user&#39;s hand with a thumb and forefinger touching the surface thereof. 
           [0035]      FIG. 4  is a top view of the touchpad showing that the touchpad sees a single object when the thumb and forefinger are touching. 
           [0036]      FIG. 5  is a top view of the touchpad showing that the touchpad sees two objects when the thumb and forefinger are separated, but are treated as a single object. 
           [0037]      FIG. 6  is a top view of the touchpad showing that the touchpad sees multiple objects when three or more fingers make contact with the touchpad, but are still treated as a single object. 
           [0038]      FIG. 7  is a top view of the touchpad showing that multiple objects may be tracked as a single large object as the multiple objects are rotated. 
           [0039]      FIG. 8  is a top view of a touchpad of the present invention showing a user&#39;s hand with a thumb and forefinger spread apart and touching the surface thereof. 
           [0040]      FIG. 9A  is a top view of a touchpad of the present invention that illustrates the new and simplified data collection algorithm that is operated in accordance with the principles of the present invention. 
           [0041]      FIG. 9B  is a graph that shows the results of the new data collection algorithm of the present invention. 
           [0042]      FIG. 10  is a top view of the touchpad that illustrates the outline of a quadrilateral that represents the outer boundaries of two pointing objects. 
           [0043]      FIG. 11  is a top view of a touchpad that shows how the three pointing objects can be seen by the new analysis algorithm when each pointing object is nearer than any other to at least one edge of the touchpad. 
           [0044]      FIG. 12  is a top view of a touchpad that shows that it is not possible to know which corners of the quadrilateral the detected objects are actually located. 
           [0045]      FIG. 13  is a top view of a touchpad that illustrates the fact that the new analysis algorithm does not determine how many pointing objects are within the boundaries of the outer pointing objects. 
           [0046]      FIG. 14  is a top view of a one-dimensional touchstrip that can also be used with the new analysis algorithm of the present invention. 
           [0047]      FIG. 15  is an alternate embodiment of the present invention, wherein the quadrilateral boundary is replaced by a form-fitting boundary that moves from object to object. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0048]    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. 
         [0049]    Before describing the embodiments of the present invention, it is important to understand that the touchpad hardware of the present invention scans all of the touchpad electrodes. The CIRQUE® touchpad has always had the ability to collect the same raw data as shown in  FIG. 2  of the prior art. The manner in which the electrodes of the touchpad are scanned is an essential element of this patent. The CIRQUE® Corporation touchpad used in the present invention appears to be unique in that electrodes are scanned sequentially in groups and not simultaneously. Nevertheless, what is relevant to the invention is how the data is gathered from the electrodes of the touchpad. The importance of the new data collection algorithm will become apparent through the disclosure below. 
         [0050]      FIG. 3  is provided as a top elevational view of a touchpad  10  that is made in accordance with the principles of the present invention. The touchpad  10  is capable of detecting and tracking multiple objects simultaneously. Consider a thumb  36  and forefinger  38  which are pressed together and placed at any location on the touchpad  10 . It is likely that the thumb  36  and forefinger  38  combination will be seen as a single object by the touchpad  10 . This is likely to occur because the tissue of the thumb  36  and forefinger  38  will likely be pressed hard enough to deform and essentially leave no gap between them when pressed against the touchpad  10 . The normal detection algorithms will operate in the manner that they presently operate when a single object is detected. That is to say that a center point or centroid is determined for the object detected. This centroid is considered to be the position on the touchpad  10  of the object detected. 
         [0051]      FIG. 4  is a top elevational view of what the touchpad  10  might detect at the location of the thumb  36  and forefinger  38  on the touchpad  10 . For example, the touchpad  10  might detect an irregular but roughly circular outline  40 , with the location of a center point  42  indicated by the crosshairs. The object  40  is an approximation only, and should not be considered as a precise representation of what is detected by the touchpad  10 . What is important to understand is that generally, only a single object will be detected. 
         [0052]    As the thumb  36  and forefinger  38  are moved apart in the reverse pinching motion, the touchpad  10  could detect two separate objects. While touchpads have been capable of detecting multiple objects since their initial development, the detection and tracking of more than one object on a touchpad surface has always been assumed to be undesirable, and so algorithms were implemented so that one of the detected objects would be ignored while the location of the desired object would continue to be tracked. The decision as to which object to track could obviously be modified. However, it has been customary in the prior art to track the largest object while ignoring the smaller object. Nevertheless, this is an arbitrary decision, and some other means of selecting which object to track can be used, such as only tracking the first object to be detected. 
         [0053]    The present invention is a new method of how to handle the detection and tracking of multiple objects. There are essentially two different scenarios. The first scenario occurs when only two objects are detected. The second scenario occurs when more than two objects are detected. 
         [0054]    An illustration of an example of the first scenario is shown in  FIG. 5 .  FIG. 5  is an illustration of what a touchpad  10  might detect when the thumb  36  and the forefinger  38  are laying sideways against the touchpad  10  when the thumb and forefinger are separated.  FIG. 5  indicates that two objects  36 ,  38  are detected, each having its own centroid  46 ,  48  respectively and shown as crosshairs. Dotted line  44  is provided to illustrate how the method of the present invention uses the data from the two objects  36 ,  38 . The dotted line  44  is used to indicate that the method of the present invention will treat the two objects  36 ,  38  as a single large object. This single object is elongated and thus appears to have two endpoints  46 ,  48 . 
         [0055]    If the thumb  36  and forefinger  38  are moved apart as shown in  FIG. 5 , then the method of the present invention treats the object as being a larger single object on the touchpad  10 . Similarly, moving the thumb  36  and forefinger  38  closer together will result in the method seeing a smaller object on the touchpad  10 , regardless of whether the thumb and forefinger are touching or not. It is emphasized that the algorithms that are needed to track a single object, be it large or small, are simpler than if the method has to track only a single object while intentionally ignoring a second object. 
         [0056]    To state the first embodiment in a succinct manner, while the present invention recognizes that two objects are physically present on the touchpad  10 , the data collection algorithms of the first embodiment will treat the two objects as if they are a single object. 
         [0057]    It should be recognized that this scenario of detecting a single large object also occurs when the palm of a hand is placed on the touchpad  10 . In fact, algorithms are typically developed to handle the situation when a large single object is detected. One typical scenario is to ignore the large object, assuming that a user has unintentionally rested the palm of a hand on the touchpad, and that no contact was intended. 
         [0058]    Consider the heel of the palm of a hand being placed on the touchpad  10 . The heel is relatively small and is a single object. Now if the palm is rocked forward so that more of the palm makes contact with the touchpad  10 , the larger palm is still a single object, and it is seen by the touchpad  10  as a single object. Thus, the new data collection algorithm of the present invention functions the same when a single large object is detected and when two objects are detected. The first embodiment is programmed to look at the points of contact and to treat them as the outer edges of a single large object, whether they are formed from a single object such as the palm of a hand or formed by two or more objects such as the thumb  36  and forefinger  38 . It should be apparent that the thumb  36  and forefinger  38  can be any two digits of a user&#39;s hand or even fingers from two different hands. 
         [0059]    The first embodiment of the present invention operates essentially in the same manner when there are more than two objects detected on the touchpad  10 . Instead of seeing endpoints, the present invention will see objects that indicate the perimeter or boundary of a single large object. Thus, the centroid of the single large object can be the “center” of the perimeter as determined by the algorithm. 
         [0060]    In  FIG. 6 , the scenario is now illustrated where more than two objects are making contact with the touchpad  10 . In a second embodiment, the touchpad  10  is programmed to use the centroids of the multiple points of contact. The centroids are the outer edges of a single large object, whether they are formed from a single object such as the palm of a hand or formed from multiple objects such as the thumb  36 , the forefinger  38  and at least one other finger. It should be apparent that the thumb  36  and forefinger  38  can also be replaced by any other digits of a user&#39;s hand or even digits of different hands. 
         [0061]    Thus in  FIG. 6  three objects  36 ,  38  and  50  are now detected. Dotted line  46  is used to show that the size of the object is determined by using the detected objects as the perimeter of the single object. 
         [0062]    Having determined that the touchpad  10  can now treat multiple objects as a single object, this information can now be used by the present invention to perform the operation described previously for zooming in and out of data on a page that is being shown on a display screen. 
         [0063]    In the scenario when two objects are detected, the single object is determined to be growing larger if the thumb  36  and forefinger  38  are performing the reverse pinching action. If the object is determined to be growing larger, then the image on the display screen is magnified when the zooming in function is being performed. Similarly, the single object is determined to be shrinking in size when the thumb  36  and the forefinger  38  are performing the pinching action. In response to the object shrinking in size, the image on the display screen is reduced in magnification, and thus the user is zooming out of the page. 
         [0064]    The invention operates the same when two or more objects are detected on the touchpad  10 . If the object is determined to be growing in size, then magnification is increased and the display screen zooms in on the data being displayed. If the object is determined to be shrinking in size, then magnification is decreased and the display screen zooms out to show more of the data. Other examples will follow that illustrate the uses of the new data collection algorithm. 
         [0065]    Another aspect of the present invention is the ability to detect the rotation of a large object on the touchpad  10 . Consider  FIG. 7  wherein multiple objects are in contact with the touchpad  10 . In this example, five objects are touching the touchpad. These five objects could be, for example, the tip of four fingers  60  and a thumb  62 . More or less objects could also be used. What is important is that the five objects are now rotated. This roughly circular motion can be interpreted to be some type of command. For example, rotation in a clockwise direction  64  could be interpreted as scrolling down in a list, and rotation in a counter-clockwise direction  66  could be interpreted as scrolling up in a list. The actual function being performed is not important. What is important is that the embodiments of the present invention enable determination of the direction of rotation so that a function can be performed. 
         [0066]    In all of the embodiments of the present invention described, it has been stated that a new data collection algorithm is used to find the edges of a boundary as defined by the multiple objects on a touchpad  10 . Thus, when a first object is detected on the touchpad  10 , the existing detection and tracking method operates as usual. But when an object appears to change in size or shape, or a second or more objects are detected, a new data collection algorithm is implemented. 
         [0067]    In  FIG. 8 , two objects are placed on the touchpad  10 . These two objects are a thumb  36  and a forefinger  38  of a user&#39;s right hand. Touchdown of the objects  36 ,  38  on the touchpad  10  may not be simultaneous, and so a single-object detection and tracking algorithm was most likely performed or was starting to be performed by the touchpad. In the single-object detection algorithm, wide and narrow scanning algorithms are used to identify a quadrant and a location within the quadrant where the object is located. 
         [0068]    Once the quadrant is identified, a narrow scanning algorithm is executed, but only within the quadrant that the object was detected. However, when the second object is detected, then the single-object algorithm is made secondary in favor of the new analysis algorithm of the present invention. 
         [0069]    In the new data collection algorithm of the present invention, analysis is performed on a touchpad  10  that is assumed to have four sides that form a rectangle. It should be apparent that the present invention is not limited to this configuration and the invention should not be considered to be limited as such. What is important is that the data collection algorithm begins at the outer edges, regardless of the number, and proceeds across the touchpad. 
         [0070]    For illustration purposes only, it is assumed that the touchpad  10  has four sides. The data generated will be a scan of the X electrode array and the Y electrode array in a typical rectangular touchpad  10 . 
         [0071]    The analysis can begin on data from either electrode array and from any edge or boundary of the electrode array. For a four sided touchpad  10 , the analysis is therefore performed a total of four times in order to analyze each electrode array from both of its outer edges and proceeding across the touchpad toward an opposite edge until an object is detected. 
         [0072]    In  FIG. 9A , we consider a data set taken from X and Y electrode arrays. The analysis from data collected from a first edge  70  (arbitrarily selected) of the X electrode array proceeds inwards or across the array as indicated by arrow  72  until an object  36  is detected at dotted line  80 . The portion of the object detected will typically only be an edge of the object. Then the analysis is repeated on the data collected for the X electrode array but from the edge opposite the first edge, which is edge  74 . Moving in the direction of arrow  76  the analysis stops as soon as the edge of an object  38  is detected at dotted line  82 . The object detected could be the same object if the two objects  36 ,  38  are in a vertical line, but in this example there is a second object  38 . Collection of data from the X electrode array is complete. 
         [0073]    Analysis then begins on a data set taken from the Y electrode array. Like the X electrode array, the analysis is performed from two outer edges  90 ,  92  moving in the direction of arrows  94  and  96  respectively until the edge of an object is detected. Thus, one complete analysis of the scanning data requires four separate scanning operations. This analysis is performed repeatedly as long as more than one object is detected by the touchpad  10 . 
         [0074]    Most touchpads are configured as either a quadrilateral or a circle. When configured as a quadrilateral, the new data collection algorithm evaluates scanning data from all four edges and proceeding inwards across the touchpad. The touchpad hardware of the present invention is only capable of performing the new data collection algorithm from only one edge at a time. However, the present invention also includes the concept of performing the new data collection algorithm from the four outer edges simultaneously. 
         [0075]    If the touchpad is configured as a circle or some other ellipsoid, then the new data collection algorithm can only be used if the touchpad is created using a quadrilateral XY electrode grid that has been cut in the shape of a circle, or has a circular overlay superimposed upon it, even though the physical XY electrode grid is a quadrilateral. What should be understood is that the new data collection algorithm can be adapted to the shape of any touchpad. 
         [0076]    In alternative embodiments, the new data collection algorithm can be utilized with more advanced shapes, such as true circles, rings, etc. The analysis should always be performed from an outer edge towards an opposite or inner area of the touchpad. 
         [0077]      FIG. 9A  illustrates the results of the new data collection algorithm of the present invention by examining a top view of the touchpad  10 . A circle is used to indicate the location on the touchpad  10  where the thumb  36  is making contact. A circle hereinafter is equivalent to the location of a pointing object making contact with the touchpad  10 . Similarly, a different circle is used to indicate the location on the touchpad  10  where the finger  38  is making contact. 
         [0078]    The touchpad groups electrodes together to perform the new data collection algorithm. Gathering data from the left edge  70  of the touchpad  10 , collecting stops when circle  36  is reached, as indicated by dotted line  80 . Collecting data from the right edge  74  of the touchpad  10 , the step of collecting data stops when circle  38  is reached, as indicated by dotted line  82 . Similarly, collecting data from the top edge  90  of the touchpad  10 , collecting data stops when circle  38  is reached, as indicated by dotted line  84 . Finally, collecting data from the bottom edge  92  of the touchpad  10 , data collection stops when circle  36  is reached, as indicated by dotted line  86 . The data collection sequence above is for illustration purposes only and should not be considered as limiting. Thus, data can be collected beginning from any edge. 
         [0079]    The other important aspect of the invention is that data collection stops as soon as the edge of any object is detected. Stopping data collection can result in a significant increase in speed of the data collection algorithms because only outer boundaries are determined. If one or both of the objects are near the outer edges of the touchpad  10 , then the data collection will occur relatively rapidly as data collection stops at the edge of each object. 
         [0080]      FIG. 9B  is a graph of the raw scanning data that is collected by the touchpad  10  of the present invention that is comparable to the graph of  FIG. 2  of the prior art. From the outer edges of a touchpad  10 , the touchpad collects data until detecting an object. Notice that no data is obtained for any object that is between the outer edges  66 ,  68  of the detected objects  36 ,  38 . To the new data collection algorithm, the detected objects appear as one large object because no information is obtained once an outer edge of the objects  36 ,  38  are detected. The algorithm might choose to simply fill in the data in the gap between the outer edges  66  and  68 , but it is not necessary. 
         [0081]      FIG. 10  is a top view of the touchpad  10 . A box  100  indicates the shape of the object that has been detected using the new data collection algorithm of the present invention. In this embodiment, the resulting shape generated by the new data collection algorithm will appear as a quadrilateral whose opposing sides are parallel. Thus, the shape will always be rectangular, with the only difference being the dimensions of the sides. 
         [0082]    In an alternative embodiment shown in  FIG. 11 , consider the three objects  102 ,  104  and  106  shown on touchpad  10 . The collection algorithm of the present invention creates the boundary as shown by the outline  108 . The outline  108  was created by three objects  102 ,  104  and  106 , and the same shape box was created using only two objects  36  and  38  in  FIG. 9A . 
         [0083]    There are some observations about the new data collection algorithm of the present invention that are not immediately apparent, but are important. 
         [0084]      FIG. 12  is a top view of the touchpad  10  that shows a quadrilateral  110 . There are four circles in the corners of the quadrilateral. The circles represent two different pairs of objects that can both create the quadrilateral  110 . Thus, circles  112  represent one pair of objects, and circles  114  represent a second pair of objects. The present invention does not generate data which would let a user of the touchpad know which pair of objects is present on the touchpad  10 . The touchpad processor that performs the analysis for the touchpad cannot determine which objects are present using the new data collection algorithm of the present invention. 
         [0085]    In an alternative embodiment, the present invention performs an analysis that can detect in which corners of the quadrilateral the objects are actually disposed. 
         [0086]    Advantageously, it is not necessary to know which pair of objects is present in order to use this information in a useful manner. For example, if the overall size of the quadrilateral  110  is shrinking, then one or both of the pointing objects on the touchpad  10  are moving towards each other. For example, both pointing objects can move in a pinching action, or one pointing object can remain stationary while the other pointing object moves towards it. 
         [0087]    Another observation of the present invention is that more than two objects may or may not be visible using the detection and tracking algorithm of the present invention. For example,  FIG. 13  is a top view of a touchpad  10  with circles  120 ,  122  and  124 . The middle pointing object  122  is not visible to the new data collection algorithm because analysis to detect pointing objects stops when the pointing objects indicated by circles  120  and  124  are reached. Thus, circle  122  is entirely within the borders of the quadrilateral  126 , and is never seen by the data collection algorithm. 
         [0088]    In contrast,  FIG. 11  shows different placements of three pointing objects  102 ,  104  and  106 . Arranged in this manner, all three circles are visible to the new data collection algorithm. Quadrilateral  108  shows that the data collection algorithm will reach each of the three circles  102 ,  104  and  106 . Therefore, the new data collection algorithm of the present invention can detect all three circles as long as each of the circles is closer to at least one edge of the touchpad  10  than any of the other circles. 
         [0089]      FIG. 14  is provided as an alternative embodiment of the present invention. A special case of the present invention can be applied to a touchpad that operates in a single dimension. Such a touchpad is sometimes referred to as a touchstrip. A touchstrip operates in a single axis which is typically but not necessarily the longest axis of the touchstrip.  FIG. 14  shows a touchstrip  130  which detects touchdown and movement along a lengthwise axis  132 . 
         [0090]    The new analysis algorithm of the present invention operates in a manner that is similar to the manner in which it operates on a general purpose touchpad described previously. However, instead of performing the new analysis algorithm from four outer edges, the touchstrip  70  only performs a scanning procedure from the outer edges  134 ,  136  that are the endpoints of the axis of operation  132 . 
         [0091]    The touchstrip  130  can still perform detection and tracking of a single pointing object. When the touchstrip detects multiple objects, the new analysis algorithm begins to scan from each of the outer edges  134 ,  136 . Scanning stops when a first pointing object  140  is detected when scanning from the outer edge  134  and when a second pointing object  142  is detected when scanning from the outer edge  136 . The new analysis algorithm will not detect touchdown of any additional pointing objects between the first and second pointing objects  140 ,  142  because there is no tracking in a second dimension, and data collection always stops when the first pointing object is detected when moving in from either outer edge. 
         [0092]    The touchstrip  130  is often used in applications that only require tracking of movement in a single dimension. For example, the touchstrip  130  can be used for scrolling, increasing the value of a variable, decreasing the value of a variable, etc. 
         [0093]    Another observation is that the prior art touchpads that can detect multiple pointing objects on a touchpad always see each pointing object on the touchpad, regardless of its position with respect to other objects on the touchpad. For example, all three circles  120 ,  122  and  124  shown in  FIG. 13  are detectable in the prior art, but not in the present invention. 
         [0094]    Another observation is that there are some unique gestures that can be performed on the touchpad  10  using the new data collection algorithm. The gestures are unique in that they do not require the tracking of multiple individual pointing objects on the touchpad in order to recognize the gesture. 
         [0095]    In one set of gestures, consider a first pointing object making touchdown and not moving. A second pointing object makes touchdown and then performs actions that are observable by the new data collection algorithm and which result in certain actions being performed. 
         [0096]    For example, the first pointing object makes touchdown in a first zone. The first zone is defined as a specific region on the touchpad that indicates that a second pointing object will indicate the function to be performed. The second pointing object can tap the touchpad, tap in a specific location, double tap, double tap in a specific location, flick towards a particular direction, make touchdown and then drag, make touchdown and then drag towards or make contact with a specific edge of the touchpad, make touchdown without any movement, or make touchdown without any movement but in a specific location. This list should not be considered as limited to the specific examples above. 
         [0097]    Another gesture that can be performed is referred to as a stake and action gesture. Thus, instead of using a specific zone, the first pointing object makes touchdown anywhere that is convenient on the touchpad, and then the second pointing object performs an action that defines what function is to be performed. The actions of the second pointing object include all the actions described above that can be combined with the first zone. 
         [0098]      FIG. 15  is provided to illustrate another alternative embodiment of the present invention. In the previous embodiments, the outline around the perimeter of the objects has always been in the shape of a quadrilateral. In this embodiment, the outline is made to conform to each of the objects detected. Thus in this example,  FIG. 15  shows that there are three objects  120 ,  122  and  14  which form a triangular object as shown by outline  128 . This embodiment may require a modification of the data collection algorithm. 
         [0099]    One aspect of the invention is related to determining the size of the quadrilateral that is formed by the detected objects. More specifically, it relates to whether or not the size is increasing or decreasing. The operation of functions can be made a function of the size of the quadrilateral. For example, if the quadrilateral is shrinking, then the user might be doing a pinching action with a thumb and forefinger. In contrast, if the quadrilateral is growing, then the user might be doing a reverse pinching action. The increasing or decreasing size of the quadrilateral can be tied to a function. Thus, the pinching action might control zooming in, and the reverse pinching action might control zooming out. Magnification or zooming is only one of many functions that can be tied to the changing size of the quadrilateral, and should not be considered limiting. 
         [0100]    A final aspect of the present invention is the ability to select a region on a touchpad that is dedicated to the new data collection algorithm of the present invention. Thus, the new data collection algorithm does not have to use the entire active sensing area of a touchpad or touchstrip. A smaller portion or region can be devoted to the new data collection algorithm. 
         [0101]    The present invention has taught a new data collection algorithm which begins at an outside edge and moves inwards or across a touchpad. Alternatively, the data collection algorithm could begin at a center and move outwards towards the outer edges of the touchpad. 
         [0102]    The present invention has also focused on the detection and tracking of objects on a rectangular touchpad. In a circular touchpad, the circular detection area could just be an overlay over a rectangular grid. However, a circular electrode grid might also be used. In a first circular embodiment, the data collection algorithm stops when it reaches a first object as the algorithm moves from the single outer edge towards the center of the touchpad, or from the center outward in all directions toward the outer edge. 
         [0103]    However, in a second circular embodiment, the circular electrode grid might be segmented into quadrants like pieces of a pie. Thus, the data collection algorithm would detect one object in each of the separate quadrants. 
         [0104]    It is to be understood that the above-described arrangements are only illustrative of the application 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.