Abstract:
Disclosed is a single-touch screen interface that supports two operational states. First is a traditional single-touch state. Second is a “simulated multi-touch state” which allows the user to interact with the single-touch screen in much the same way as he would interact with a multi-touch screen. The user, while in the single-touch state, selects the simulated multi-touch state by performing a special “triggering” action, such as clicking or double clicking on the display screen. The location of the triggering input defines a “reference point” for the simulated multi-touch state. While in the simulated multi-touch state, this reference point is remembered, and it is combined with further touch input to control a simulated multi-touch operation. When the simulated multi-touch operation is complete, the interface returns to the single-touch state. In some embodiments, the user can also leave the simulated multi-touch state without completing a simulated multi-touch operation.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention is related generally to user interfaces for computing devices and, more particularly, to touch-screen interfaces. 
       BACKGROUND OF THE INVENTION 
       [0002]    Touch screens are becoming very common, especially on small, portable devices such as cellular telephones and personal digital assistants. These small devices often do not have enough room for a full-size keyboard. Touch screens allow them to simultaneously use the “real estate” of their display screens both for display and for input. 
         [0003]    The vast majority of touch screens are “single-touch,” that is, their hardware and software can only resolve one touch point at a time. If a user simultaneously touches a single-touch screen at more than one place, then the screen may either interpolate the multiple touches into one irrelevant touch point or, upon recognizing that multiple touches are present but not being able to resolve them, may not register a touch at all. A user of a single-touch screen quickly learns not to accidentally let his palm or multiple fingers rest against the screen. Despite this limitation, single-touch screens are very useful, and users are beginning to expect them on new devices. 
         [0004]    “Multi-touch” screens have been developed that can resolve more than one simultaneous touch. Users find these screens very useful, because multiple touches allow users to simultaneously control multiple aspects of a display interface. Making an analogy to music, using a single-touch screen is like playing a single-finger rendition of a song on a piano: Only the melody can be rendered. With multi-touch, a ten-finger piano player can add harmony and accompanying themes to the melody line. 
         [0005]    For the time being, however, multi-touch screens will remain somewhat rare due to their substantially greater cost and complexity when compared to single-touch screens. 
       BRIEF SUMMARY 
       [0006]    The above considerations, and others, are addressed by the present invention, which can be understood by referring to the specification, drawings, and claims. According to aspects of the present invention, many of the benefits of an expensive multi-touch screen are provided by an inexpensive single-touch screen supported by enhanced programming. The enhanced programming supports two operational states for the single-touch screen interface. First is the single-touch state in which the screen operates to support a traditional single-touch interface. Second is a “simulated multi-touch state” in which the programming allows the user to interact with the single-touch screen in much the same way as he would interact with a multi-touch screen. 
         [0007]    In some embodiments, the user, while in the single-touch state, selects the simulated multi-touch state by performing a special “triggering” action, such as clicking or double clicking on the display screen. The location of the triggering input defines a “reference point” for the simulated multi-touch state. While in the simulated multi-touch state, this reference point is remembered, and it is combined with further touch input (e.g., clicks or drags) to control a simulated multi-touch operation. When the simulated multi-touch operation is complete, the interface returns to the single-touch state. In some embodiments, the user can also leave the simulated multi-touch state by either allowing a timer to expire without completing a simulated multi-touch operation or by clicking a particular location on the display screen (e.g., on an actionable icon). 
         [0008]    As an example, in one embodiment, the reference point is taken as the center of a zoom operation, and the user&#39;s further input while in the simulated multi-touch state controls the level of the zoom operation. 
         [0009]    Operations other than zoom are contemplated, including, for example, a rotation operation. Multiple operations can be performed simultaneously. In some embodiments, the user can redefine the reference point while in the simulated multi-touch state. 
         [0010]    Some embodiments tie the simulated multi-touch operation to the application software that the user is running. For example, a geographical navigation application supports particular zoom, transfer, and rotation operations with either single-touch or simulated multi-touch actions. Other applications may support other operations. 
         [0011]    It is expected that most early implementations will be made in the software drivers for the single-touch display screen, while some implementations will be made in the user-application software. Some future implementations may support the simulated multi-touch state directly in the firmware drivers for the display screen. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0012]    While the appended claims set forth the features of the present invention with particularity, the invention, together with its objects and advantages, may be best understood from the following detailed description taken in conjunction with the accompanying drawings of which: 
           [0013]      FIGS. 1   a  and  1   b  are simplified schematics of a personal communication device that supports a simulated multi-touch screen according to aspects of the present invention; 
           [0014]      FIG. 2   a  is an initial view of a map,  FIG. 2   b  is a desired view of the map of  FIG. 2   a,  and  FIG. 2   c  is an action diagram showing how a user moves from the view of  FIG. 2   a  to the view of  FIG. 2   b  using a widget-based, single-touch user interface; 
           [0015]      FIG. 3  is an action diagram showing how a user moves from the view of  FIG. 2   a  to the view of  FIG. 2   b  using a multi-touch user interface; 
           [0016]      FIG. 4  is a flowchart of an exemplary method for simulating a multi-touch operation on a single-touch screen; 
           [0017]      FIG. 5  is an action diagram showing how a user moves from the view of  FIG. 2   a  to the view of  FIG. 2   b  using a simulated multi-touch user interface; and 
           [0018]      FIG. 6  is a table comparing the actions the user performs in the methods of  FIGS. 2   c,    3 , and  5 . 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    Turning to the drawings, wherein like reference numerals refer to like elements, the invention is illustrated as being implemented in a suitable environment. The following description is based on embodiments of the invention and should not be taken as limiting the invention with regard to alternative embodiments that are not explicitly described herein. 
         [0020]      FIGS. 1   a  and  1   b  show a personal portable device  100  (e.g., a cellular telephone, personal digital assistant, or personal computer) that incorporates an embodiment of the present invention in order to provide many of the advantages of a multi-touch display screen with a less expensive single-touch screen.  FIGS. 1   a  and  1   b  show the device  100  in an open configuration, presenting its main display screen  102  to a user. In the present example, the main display screen  102  is a single-touch screen. Typically, the main display  102  is used for most high-fidelity interactions with the user. For example, the main display  102  is used to show video or still images, is part of a user interface for changing configuration settings, and is used for viewing call logs and contact lists. To support these interactions, the main display  102  is of high resolution and is as large as can be comfortably accommodated in the device  100 . 
         [0021]    The user interface of the personal portable device  100  includes, in addition to the single-touch screen  102 , a keypad  104  or other user-input devices. 
         [0022]    A typical personal portable device  100  has a second and possibly a third display screen for presenting status messages. These screens are generally smaller than the main display screen  102 , and they are almost never touch screens. They can be safely ignored for the remainder of the present discussion. 
         [0023]      FIG. 1   b  illustrates some of the more important internal components of the personal portable device  100 . The device  100  includes a communications transceiver  106  (optional but almost ubiquitous), a processor  108 , and a memory  110 . In many embodiments, touches detected by a hardware driver for the single-touch screen  102  are interpreted by the processor  108 . Applying the methods of the present invention, the processor  108  then alters the information displayed on the single-touch screen  102 . 
         [0024]    Before describing particular embodiments of the present invention, we consider how a user can navigate within a map application using various user interfaces.  FIG. 2   a  shows an initial view of a map displayed on the screen  102  of the personal portable device  100 . The user is interested in the portion of the map indicated by the circled area  200 .  FIG. 2   b  shows the map view that the user wants. Compared with the initial view in  FIG. 2   a,  the desired view in  FIG. 2   b  has a different center, has been zoomed in, and has been rotated slightly. 
         [0025]      FIG. 2   c  illustrates a traditional, single-touch interface for the map application. To support navigation, the interface of  FIG. 2   c  includes four actionable icons (or “widgets”). Touching widget  202  increases the zoom of the map display, while widget  204  reduces the zoom. Widgets  206  and  208  rotate the map clockwise and counterclockwise, respectively. 
         [0026]    To use the interface of  FIG. 2   c  to navigate from the initial view of  FIG. 2   a  to the desired view of  FIG. 2   b,  the user begins by touching the desired center point of the map and then “drags” that point to the map center. This is illustrated in  FIG. 2   c  by the solid arrow from the center of the area  200  to the center of the display  102 . 
         [0027]    Next, the user raises his finger (or stylus or whatever pointing device he is using to interact with the single-touch screen  102 ), moves to the widget area, and clicks on the zoom widget  202 . This is illustrated by a dotted arrow. The user may need to zoom in and out using widgets  202  and  204  until the correct zoom level is achieved. This is illustrated by the dotted arrow joining these two zoom widgets  202  and  204 . 
         [0028]    With the zoom set, the user moves his finger through the air (dotted arrow) to the pair of rotation widgets  206  and  208 . Again, the user may have to click these widgets multiple times to achieve the correct rotation (dotted arrow joining the rotation widgets  206  and  208 ). 
         [0029]    Finally, the user may need to move his finger in the air (dotted arrow) to the middle of the display screen  102  and readjust the map center by dragging (short solid arrow). 
         [0030]      FIG. 6  is a table that compares the actions needed in various user interfaces to move from the initial view of  FIG. 2   a  to the desired view of  FIG. 2   b.  For the traditional, widget-based, single-touch interface of  FIG. 2   c,  the navigation can take 4+(2*M) actions, including dragging to re-center the view, moving through the air to select the widgets, moving back and forth among each pair of widgets to set the correct zoom level and rotation amount, and moving back to the center of the display  102  to adjust the centering. 
         [0031]    Next consider the same task where the display screen  102  supports multiple touches. This is illustrated in  FIG. 3 . Here the user makes two simultaneous motions. One motion drags the map to re-center it, while the other motion adjusts both the zoom and the rotation. (Because a motion occurs in two dimensions on the display screen  102 , the vertical aspect of the motion can be interpreted to control the zoom while the horizontal aspect controls the rotation. Other implementations may interpret the multiple touches differently.) As seen in  FIG. 6 , by interpreting simultaneous touches, a multi-touch screen allows the user to make the navigation from the initial view in  FIG. 2   a  to the desired view of  FIG. 2   b  in a single, multiple touch, action. 
         [0032]    With the advantages of the multi-touch screen fully in mind, we now turn to aspects of the present invention that simulate a multi-touch interface on a less expensive single-touch screen. Note that it is contemplated that different applications may support different simulated multi-touch interfaces.  FIG. 4  presents one particular embodiment of the present invention, but it is not intended to limit the scope of the following claims. The user interface begins in the traditional single-touch state (step  400 ). When the user clicks (or double clicks) on the single-touch display screen  102 , the location of the click is compared against the locations of any widgets currently on the screen  102 . If the click location matches that of a widget, then the widget&#39;s action is performed, and the interface remains in the single-touch state. 
         [0033]    Otherwise, the click is interpreted as a request to enter the simulated multi-touch state (step  402 ). The location of the click is stored as a “reference point.” In some embodiments, a timer is started. If the user does not complete a simulated multi-touch action before the timer expires, then the interface returns to the single-touch state. 
         [0034]    In some embodiments, the user can redefine the reference point while in the simulated multi-touch state (step  404 ). The user clicks or double clicks anywhere on the screen  102  except for on a widget. The click location is taken as the new reference point. (If the user clicks on a widget while in the simulated multi-touch state, the widget&#39;s action is performed, and the interface returns to the single-touch state. Thus, a widget can be set up specifically to allow the user to cleanly exit to the single-touch state.) In other embodiments, the user must exit to the single-touch state and re-enter the simulated multi-touch state in order to choose a new reference point. 
         [0035]    In any case, while in the simulated multi-touch state, the user can make further touch input (step  406 ), such as a continuous drawing movement. 
         [0036]    The reference point and this further touch input are interpreted as a command to perform a simulated multi-touch action (step  408 ). If, for example, the user is performing a zoom, the reference point can be taken as the operation center of the zoom while the further touch input can define the level of the zoom. For a second example, the reference point can define the center of a rotation action, while the further touch input defines the amount and direction of the rotation. In other embodiments, the center of an action can be defined not by the reference point alone but by a combination of, for example, the reference point and the initial location of the further touch input. Multiple actions, such as a zoom and a rotation, can be performed together because the further touch input can move through two dimensions simultaneously. In this manner, the simulated multi-touch action can closely mimic the multi-touch interface illustrated in  FIG. 3 . 
         [0037]    When the simulated multi-touch action is complete (signaled, for example, by the end of the further touch input, that is, by the user raising his finger from the single-touch screen  102 ), the user interface returns to the single-touch state (step  410 ). 
         [0038]    The example of  FIG. 5  ties this all together. Again, the user wishes to move from the initial map view of  FIG. 2   a  to the desired view of  FIG. 2   b.  In  FIG. 5 , the single-touch display screen  102  supports a simulated multi-touch interface. The user enters the simulated multi-touch state by clicking (or double clicking) on the center of the circular area  200 . The click also defines the center of the circular area  200  as the reference point. (Note that there are no widgets defined on the screen  102  in  FIG. 5 , so the user&#39;s clicking is clearly meant as a request to enter the simulated multi-touch state.) The user&#39;s further touch input consists of a continuous drawing action that re-centers the view (illustrated by the long, straight arrow in  FIG. 5 ). In a second simulated multi-touch action, the user clicks in the center of the view to generate a new reference point and then draws to adjust both the zoom and the rotation (medium length curved arrow in the middle of  FIG. 5 ). Finally, the user adjusts the centering in a single-touch drag action (short straight arrow to the right of  FIG. 5 ). 
         [0039]    Turning back to the table of  FIG. 6 , the simulated multi-touch interface of  FIG. 5  requires only three short actions, clearly much better than the traditional single-touch interface. The combination of the defined reference point and the further touch input gives the simulated multi-touch interface enough information to simulate a multi-touch interface even while only recognizing one touch point at a time. Because the further touch input takes place in two dimensions, two operations can be performed simultaneously. Also, the user can carefully adjust these two operations by moving back and forth in each of the two dimensions. 
         [0040]    The above examples are appropriate to a map application. Other applications may define the actions performed in the simulated multi-touch interface differently. 
         [0041]    In view of the many possible embodiments to which the principles of the present invention may be applied, it should be recognized that the embodiments described herein with respect to the drawing figures are meant to be illustrative only and should not be taken as limiting the scope of the invention. For example, the specific interpretation of touches can vary with the application being accessed. Therefore, the invention as described herein contemplates all such embodiments as may come within the scope of the following claims and equivalents thereof.