Incontrol Solutions, Inc.

Home Row, Inc.

Philip D Biehl

Patrick J Franz

David H Straayer

Daniel R Brown

Robert H Dodier

In a cursor tracking system (FIG. 11), a pointing device includes a plurality of force sensors (304), optionally integrated with a keyswitch on a computer keyboard. The force sensors detect lateral and vertical forces applied to the keycap (300) by a user (302) for cursor control. Raw force data is acquired by A/D apparatus (306) and transmitted (310,312) to a host processor. Driver level software in the host linearizes the raw force values (316, FIG. 12D) to compensate for anomolies and nonlinearities in the force sensors, keyboard mechanics, and A/D. The resulting linear force values are adjusted (320) to compensate for preloading bias forces (318) on the sensors. The unbiased, linear force values and sensor configuration (322) are used to determine a net XY vector (324, FIG. 16). A speed value is determined by a quadratic mapping of the XY vector magnitude (328), taking mouse button status into account. The speed value is scaled by a speed factor, clamped according to a speed limit value, and the result used to determine a total displacement value which, in turn, is used to scale the XY vectors to determine X and Y cursor displacement for repositioning the cursor. The quadratic mapping coefficients, as well as the speed factor and speed limit values, are user-alterable at run time, to allow customizing the response of the cursor tracking system. The result is a low-cost pointing system having excellent responsiveness for ergonomic efficiency. The system is useful in most computer systems, such as IBM AT-compatible systems, to allow pointing operations without use of a separate pointing device such as a mouse.

Cursor tracking

Methods and apparatus are disclosed for normalizing electronic sensor data to correct for variations in individual sensor transfer characteristics which are not known in advance. A general characteristic transfer function for a sensor type of interest is determined empirically. A baseline response reading is acquired from an individual sensor, and that baseline response applied to the general transfer function to determine a specific transfer function for the individual sensor. The specific transfer function is used to calculate normalized data. One application of the invention is in computer cursor control pointing devices such as a joystick. Because the invention compensates for wide variations in sensor characteristics, inexpensive sensors such as force-sensitive resistors may be used in a joystick without sacrificing pointing accuracy and ergonomic efficiency.

Electronic force sensing with sensor normalization

Data acquisition in a multi-function keyboard system includes both acquiring typing data by conventional keyboard scanning techniques and, simultaneously, acquiring pointing data by sampling force sensors coupled to the multi-function pointing key. The keyboard system periodically samples the force sensors to determine bias values defining a null point, and updates the bias values by a moving average calculation to compensate for manufacturing tolerance and long term drift. In response to a start pointing command from the host processor, the keyboard system transmits bias values and then pointing values, the latter being responsive to forces applied to the pointing key by the user for cursor control. The sensor values are encoded so as to pass through to the host processor in a manner transparent to application software. The system scans the force sensors periodically to acquire successive pointing values, and transmits them to the host, as long as pointing mode persists. Concurrently, the keyboard system scans the keyboard to detect other key changes and forwards them to the host as well. The keyswitch data may be interpreted as a pointing event (analogous to a mouse button action), or as an indication to change to typing mode.

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Tigard, OR, United States of America

Philip D Biehl