Conventional input devices, such as computer mice, typically employ optical sensors, track wheels or track balls to control the motion of a cursor or other navigational object on a computer display screen. Other types of input devices that measure a force imparted onto the input device typically incorporate one or more accelerometers for sensing acceleration forces exerted on the input device as it is moved by a user. A velocity of the electronic input device may be calculated and estimated by integrating the measured acceleration over time, and a position estimate of the input device may be calculated by integrating its velocity over time. In this way, motion of an accelerometer-based input device may be translated to motion of a cursor or other navigational object on a computer display screen.
Touch-sensitive panels can also be used as an input device to control the motion of a cursor or other navigational object on a computer display screen. One common type of touch-sensitive panel is a touch pad. In general, touch-sensitive panels can detect one or more touch contacts on the surface of the touch-sensitive panel and generate signals indicative of the touch contacts. A computer can then control a cursor or other navigational object based on the detected touch contacts.
Various problems are associated with conventional input devices. For example, most, if not all, conventional input devices are inadequate in tracking both large and fine motions. For example, inertial sensing-based input devices typically track large ranges of motion well (e.g., moving a cursor across the length of a display screen), but not fine ranges of motions. In contrast, touch-sensitive pads typically track fine ranges of motions well, but not large ranges of motion. For example, moving a cursor from one end of the display screen to the other end may require a user to swipe his or her finger across a touch pad multiple times before the cursor moves to the other end of the display screen.