Patent Publication Number: US-8120578-B2

Title: Controller system and method for controlling a cursor

Description:
RELATED APPLICATIONS 
     This application is a Continuation application of U.S. patent application Ser. No. 10/720,186, filed on Nov. 25, 2003 now U.S. Pat. No. 7,432,908. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a controller, system and method for controlling a cursor and, more particularly, to a controller, system and method for controlling a cursor in which an input parameter signal is calibrated using a first hands-off test when a cursor is in motion and a second hands-off test, different than the first hands-off test, when a cursor is not in motion. 
     2. Description of the Related Art 
     Pointing stick cursor control systems, such as the TrackPoint® system, sense finger force at high precision (compared to overload capacity) and translate it (via a transfer function) to velocity of movement of the cursor on the graphical user interface (GUI) display screen. The electrical signals produced by the sensing element are necessarily small (microvolts) and subject to relatively slow drift due to temperature and other environmental changes. 
     This drift must be detected and removed from the significant signal, otherwise incorrect movement signals will be transmitted, with the most noticeable effect being spontaneous movement of the cursor. This is done by identifying periods when the stick is not being touched (hands-off periods), and using the signal detected at these times as the ‘zero’ signal, relative to which a significant signal is measured (calibrating). 
     To prevent cursor movement from a minimal signal change before it can be corrected, cursor movement is produced only when a certain minimal relative signal is detected. That is, there is a dead band in the transfer function—signal values close to but not zero for which no movement is produced. 
     Hands-off periods may be identified from the properties of the signal itself, or some other means, e.g. a capacitive proximity detector, may be used alone or in combination. In any case this can be done only probabalistically—a small force applied perfectly steadily may exactly mimic a temperature drift, and proximity may not mean contact—with the probability of error depending on the noise level (e.g., high frequency &gt;10 Hz), the signal analysis and other detection method, the length of the signal sample analyzed, and perhaps other factors. 
     Since the signal is small, control of the noise level is difficult. The testing time should be made as short as possible for two principle reasons. First, the user may touch the stick almost continuously, and the shorter the testing time, the more frequently recalibration can be done and the less likely it is that the signal drift will become large enough to cause cursor drift. Secondly, if cursor drift does occur, it will continue until the stick is untouched for at least a testing time. Further, since signal drift normally occurs slowly (e.g., with temperature or other environmental change), there will normally be an extended period when it is detectable but still within the dead band. This allows a recalibration before a cursor movement occurs, and normally avoids spontaneous cursor movement. 
     However, this may fail for either of two reasons. First, it may fail if the hands-off test fails continuously while the signal drifts outside the dead band relative to its initial value. Second, it may fail if a “hands-off” period is detected in error, and a recalibration occurs to a signal value which is actually outside the dead band relative to the true “hands-off” signal. In the latter case, the cursor, which is properly in motion, stops and when the stick is released it moves with the opposite velocity until a correct recalibration occurs (e.g., for at least the testing time, and longer if the user interferes). 
     These two failure causes are conflicting. That is, the first cause may be avoided by making the test less stringent (e.g. shortening the testing time), and the second cause may be avoided by making the test more stringent (e.g. lengthening the testing time). Thus, the solution to date for the TrackPoint system has been to choose a compromise value, first 2.88 seconds with measurement precision 3.2 grams, and currently 0.53 seconds with precision 0.8 grams. 
     Further, in some other pointing stick systems, an input signal is never recalibrated when the cursor is in motion (the more-stringent test always fails) so that the second case error cannot occur. When cursor drift does occur (due to a first-case error), it continues until the user intervenes, with a special key or a reboot. 
     Thus, in spite of these and other attempts, cursor drift continues to be a nuisance. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing and other problems, disadvantages, and drawbacks of the aforementioned conventional systems and methods, it is a purpose of the exemplary aspects of the present invention to provide a controller, system and method for controlling a cursor which has an improved control of cursor drift. 
     The present invention includes a controller for controlling a cursor, which includes an identifying module for identifying at least one of a first period when the cursor is in motion and a second period when the cursor is not in motion, and a calibrating module for calibrating an input parameter signal (e.g., to inhibit a cursor drift) using a first hands-off test during the first period. 
     Further, the identifying module may input the input parameter signal from a force sensor, and the calibrating module may output a calibrated input parameter signal to an output module. Further, the input parameter signal may include an input parameter signal detected during a period when the force sensor is untouched (e.g., by a user). In addition, a transfer function for generating the cursor movement signal may include a dead band such that the cursor movement signal causes no cursor movement whenever the calibrated input parameter signal has a value within said dead band. 
     Further, the calibrating module may calibrate the input parameter signal during a hands-off period. That is, the first and second hands-off tests may be used by the calibrating module to determine a hands-off period during which a device (e.g., a pointing stick) for controlling the cursor is not being touched by a user. The calibrating module may then set a signal (e.g., input parameter signal) detected during the hands-off period as a zero signal, relative to which a significant signal (e.g., input parameter signal) is measured. 
     Further, in an exemplary aspect of the present invention, the first hands-off test may include a duration of at least about 5 seconds, and the second hands-off test may include no more than about 0.53 seconds. 
     Another exemplary aspect of the present invention includes a cursor control system which includes a force sensor (e.g., a pointing device which is attached to (e.g., included in) the keyboard assembly) which generates an input parameter signal, and a controller operably coupled to the force sensor. The controller includes an identifying module for identifying at least one of a first period when a cursor is in motion and a second period when the cursor is not in motion, and a calibrating module for calibrating an input parameter signal using a first hands-off test during the first period and a second hands-off test, different than the first hands-off test during the second period. 
     Another exemplary aspect of the present invention includes a keyboard assembly including the inventive cursor control system. For example, the force sensor may include a pointing device which is in a keyboard. 
     Another exemplary aspect of the present invention includes a computer system which includes a keyboard assembly including the inventive cursor control system, and a display device for displaying a cursor controlled by the cursor control system. 
     Another exemplary aspect of the present invention includes a method of controlling a cursor. The method includes identifying at least one of a first period when a cursor is in motion and a second period when the cursor is not in motion, and calibrating an input parameter signal using a first hands-off test during the first period and a second hands-off test different than (e.g. less stringent than) the first hands-off test during the second period. 
     In one exemplary aspect, the method of controlling a cursor includes identifying at least one of a first period when a cursor is in motion and a second period when the cursor is not in motion, determining a hands-off period during which a device for controlling the cursor is not being touched by a user, by using a first hands-off test during the first period and a second hands-off test different than the first hands-off test during the second period, and calibrating a significant input parameter signal by identifying an input parameter signal detected during the hands-off period as having a zero value, relative to which said significant input parameter signal is measured. 
     The present invention also includes a programmable storage medium tangibly embodying a program of machine-readable instructions executable by a digital processing apparatus to perform the inventive method. 
     With its unique and novel features, the present invention provides a controller, system and method for controlling a cursor which has an improved control of cursor drift over conventional controllers, systems and methods. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other objects, aspects and advantages will be better understood from the following detailed description of the embodiments of the invention with reference to the drawings, in which: 
         FIG. 1  illustrates a controller  100  for controlling a cursor and a cursor control system  150 , in accordance with an exemplary aspect of the present invention. 
         FIG. 2  illustrates a keyboard assembly  250 , in accordance with an exemplary aspect of the present invention; 
         FIG. 3  illustrates a method  300  of controlling a cursor, in accordance with an exemplary aspect of the present invention; 
         FIG. 4  illustrates a typical hardware configuration  400  that may be used to implement the controller  100 , cursor control system  150  and method  300  of controlling a cursor, in accordance with an exemplary aspect of the present invention; and 
         FIG. 5  illustrates a magnetic data storage diskette  500  that may be used to store instructions for performing the inventive method  300 , in accordance with an exemplary aspect of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION 
     Referring now to the drawings,  FIG. 1  illustrates a controller  100  for controlling a cursor according to an exemplary aspect of the present invention. As shown in  FIG. 1 , the controller  100  may include an identifying module  110  for identifying at least one of a first period when a cursor is in motion and a second period when the cursor is not in motion, and a calibrating module  120  for calibrating an input parameter signal  105  using a first hands-off test during the first period and a second hands-off test different than the first hands-off test, during the second period. 
     As illustrated in  FIG. 1 , the controller  100  may input a parameter signal  105  from a force sensor  200 , and output a calibrated input parameter signal (e.g., calibrated force signal)  122  to an output module  130 , which may output a cursor movement signal  125  based on the calibrated force signal  122 . 
     Further, in the exemplary embodiment of  FIG. 1 , the identifying module  110  and the calibrating module  120  are provided together. Alternatively, these features may be separately provided (e.g., remotely provided) in the present invention. For example, the controller  100  may include several separate and distinct components for providing its features. 
     As further illustrated in  FIG. 1 , another exemplary aspect of the present invention includes a cursor control system  150  which includes a force sensor  200  which generates an input parameter signal, the inventive controller  100  operably coupled to the force sensor, for generating a calibrated force signal  122 , and an output module  130  which outputs a cursor movement signal  125  based on the calibrated force signal  122 . 
     As illustrated in  FIG. 2 , another exemplary aspect of the present invention includes a keyboard assembly  250  which may be used in accordance with the exemplary aspects of the present invention. For example, features of the controller  100  and/or the cursor control system  150  may be included in (e.g., attached to) the keyboard assembly  250 . For example, the keyboard assembly  250  may include a keypad  260  and a pointing device  270  which is included as part of the keyboard assembly  250 . 
     In this exemplary aspect, the pointing device  270  may include, for example, the force sensor  200  of the cursor control system  150 . Further, the controller  100  may be formed adjacent to the pointing device  270  in the keyboard assembly  250 , or it may be located elsewhere. The keyboard assembly  250  may also include selection buttons  280  associated with the pointing device  270 , and may be included with a display device as part of a computer system (e.g., a graphical user interface (GUI)). 
     The cursor control system of the present invention may be incorporated into a graphical user interface cursor positioning device such as that described in Barrett et al, “Graphical User Interface Cursor Positioning Device Having a Negative Inertia Transfer Function” (U.S. Pat. No. 5,570,111), which is commonly assigned with the present invention, and is incorporated herein by reference. 
     The pointing stick may be operated with a fingertip, placed on the cap of the pointing stick which may extend, for example, about 1 mm above the adjacent keys. 
     Functionally, the pointing stick provides cursor positioning and graphic input, duplicating the function of a mouse or trackball, but without requiring the user to leave typing position, and without any additional device to be carried, or requiring desk space. Special processing gives the user a sense of ease of use and positive control. 
     The pointing stick system may include an internal processing element (e.g., the controller  100  illustrated in  FIG. 1 ) which interfaces with the host through the auxiliary device port. The logical function and electrical interface may be compatible with the mouse and mouse drivers and other software may be used unaltered. 
     A user may operate the pointing stick system  270  by pushing laterally against the top of the pointing stick with his fingertip. The pointing stick does not necessarily displace, as in the case of a joystick. The input parameter includes the force applied by the user, and the force is mapped to cursor movement. The force against the device is sensed, and the cursor movement is made at a rate determined by the transfer function, over the length of time the pressure is applied. 
     The speed of cursor movement may be proportional to the magnitude of the force applied, or have some other predetermined relationship, as defined by the device&#39;s transfer function. For example, the pointing device system may be implemented as having a sigmoid transfer function, including a “dead zone” in which very small forces are ignored, and a series of regions in the input parameter domain, where, in each region, the cursor movement is a piecewise linear function of the input parameter. The piecewise linear segments approximate the sigmoid shape. 
     A solution offered by the present invention is to separate the problem of conventional systems into two parts, that is, when the cursor is in motion, and when it is not. When the cursor is in motion, the present invention considers it to be very unlikely that the stick is untouched, so first test (e.g., a very stringent test) is applied. For example, a test time of 5 to 10 seconds with precision of 0.8 grams may be used. It is very unlikely that an erroneous hands-off detection will occur, although if the cursor is in fact drifting, it will continue to do so for a long time. 
     On the other hand, when the cursor is not in motion, a different hands-off test (e.g., much more lenient test) is applied. For example, a test time of 0.53 seconds may be used. This can catch small hands-off intervals, and track rapid temperature changes. In this case, even if hands-off is incorrectly reported, little harm is done since no erroneous cursor movement will result. 
     Further, an error causing cursor drift in the present invention is extremely rare. So rare, in fact, that the average user will likely never see it. 
     Referring again to the drawings, as illustrated in  FIG. 3 , another aspect of the present invention includes a method  300  of controlling a cursor. The method  300  includes identifying ( 310 ) at least one of a first period when a cursor is in motion and a second period when the cursor is not in motion, and calibrating ( 320 ) an input parameter signal using a first hands-off test during the first period and a second hands-off test different than (e.g. less stringent than) the first hands-off test during the second period. For example, the inventive method  300  may include the features similar to that of the inventive controller  100  outlined above. 
     Referring now to  FIG. 4 , system  400  illustrates a typical hardware configuration which may be used for implementing the inventive cursor control system and method of controlling a cursor. The configuration has preferably at least one processor or central processing unit (CPU)  411 . The CPUs  411  are interconnected via a system bus  412  to a random access memory (RAM)  414 , read-only memory (ROM)  416 , input/output (I/O) adapter  418  (for connecting peripheral devices such as disk units  421  and tape drives  440  to the bus  412 ), user interface adapter  422  (for connecting a keyboard  424 , mouse  426 , speaker  428 , microphone  432 , pointing stick  427  and/or other user interface device to the bus  412 ), a communication adapter  434  for connecting an information handling system to a data processing network, the Internet, an Intranet, a personal area network (PAN), etc., and a display adapter  436  for connecting the bus  412  to a display device  438  and/or printer  439 . Further, an automated reader/scanner  441  may be included. Such readers/scanners are commercially available from many sources. 
     In addition to the system described above, a different aspect of the invention includes a computer-implemented method for performing the above method. As an example, this method may be implemented in the particular environment discussed above. 
     Such a method may be implemented, for example, by operating a computer, as embodied by a digital data processing apparatus, to execute a sequence of machine-readable instructions. These instructions may reside in various types of signal-bearing media. 
     Thus, this aspect of the present invention is directed to a programmed product, including signal-bearing media tangibly embodying a program of machine-readable instructions executable by a digital data processor to perform the above method. 
     Such a method may be implemented, for example, by operating the CPU  411  to execute a sequence of machine-readable instructions. These instructions may reside in various types of signal bearing media. 
     Thus, this aspect of the present invention is directed to a programmed product, including signal-bearing media tangibly embodying a program of machine-readable instructions executable by a digital data processor incorporating the CPU  411  and hardware above, to perform the method of the invention. 
     This signal-bearing media may include, for example, a RAM contained within the CPU  411 , as represented by the fast-access storage for example. Alternatively, the instructions may be contained in another signal-bearing media, such as a magnetic data storage diskette  500  ( FIG. 5 ), directly or indirectly accessible by the CPU  411 . 
     Whether contained in the computer server/CPU  411 , or elsewhere, the instructions may be stored on a variety of machine-readable data storage media, such as DASD storage (e.g, a conventional “hard drive” or a RAID array), magnetic tape, electronic read-only memory (e.g., ROM, EPROM, or EEPROM), an optical storage device (e.g., CD-ROM, WORM, DVD, digital optical tape, etc.), paper “punch” cards, or other suitable signal-bearing media including transmission media such as digital and analog and communication links and wireless. In an illustrative embodiment of the invention, the machine-readable instructions may comprise software object code, compiled from a language such as C, C+, etc. 
     With its unique and novel features, the present invention provides a controller, system and method for controlling a cursor which has an improved control of cursor drift over conventional controllers, systems and methods. 
     While the invention has been described in terms of one or more embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the appended claims. Specifically, one of ordinary skill in the art will understand that the drawings herein are meant to be illustrative, and the design of the inventive assembly is not limited to that disclosed herein but may be modified within the spirit and scope of the present invention. 
     Further, Applicant&#39;s intent is to encompass the equivalents of all claim elements, and no amendment to any claim the present application should be construed as a disclaimer of any interest in or right to an equivalent of any element or feature of the amended claim.