A threshold discrimination filter circuit compares signals output by a graphic input device such as an isometric joystick including strain gauges and a fixed resistance in a hierarchical voltage divider with threshold reference signals and corrects the output of the graphic input device based on previously stored samples thereof when a selection or deselection action by a user is discriminated to values at a time of onset of selection. Onset of selection may be achieved by estimating maximum curvature of a plot of output values over time. Changes in output signals during selection and other signal signatures such as would correspond to a lift are exploited to provide a plurality of selection operations which can be recognized. User actions may be adaptively captured to increase discrimination capability (e.g. resolution) and/or user recognition. Outputs of the graphic input device are supplied directly to a CPU of a data processing device between masking periods so that graphic manipulations such as dragging can be performed while masking unintended change of specified display location during selection and deselection.

A pressure sensitive pointing device or pen is described for use with an electronic tablet that determines the position of the pointing device on the surface of the tablet. The pointing device incorporates a variable reluctance circuit responsive to the force exerted on the pen point for modulating a radiating frequency, emanating from the pen, in proportion to the force.

A system comprising a conductive stylus used in conjunction with a capacitance sensitive touch pad, said system providing at least two different signals to an associated computer system. The stylus is a pen-like device having an actuable switch which when actuated substantially increases the capacitive disturbance caused by the conductive stylus on the touch pad. Before actuation, the stylus creates a capacitive disturbance sufficient for circuitry in the touch pad to measure as crossing a first predefined capacitive disturbance threshold when the foam covered conductive stylus tip is brought in contact with the surface of the touch pad. When the switch is actuated, the capacitive disturbance measured by the touch pad increases sufficient to cross a second predefined capacitive disturbance threshold. An associated computer program for drawing on a computer display places a cursor on the display when the first threshold is crossed. The computer program begins drawing on the display beginning at the cursor location when the switch is actuated causing the second threshold to be crossed. Placing a conductive foam cover over the conductive stylus tip results in the measured capacitive disturbance being amplified to thereby increase the magnitude of the capacitive disturbance of the stylus.

The invention concerns a stylus for use with a digitizing tablet. The stylus stores information which identifies characteristics of a user's handwriting. These characteristics are transmitted to a computer when the user interfaces with the computer, and are used by the computer to recognize the user's handwriting.

The invention concerns a stylus for use with a digitizing tablet. The stylus stores information which identifies characteristics of a user's handwriting. These characteristics are transmitted to a computer when the user interfaces with the computer, and are used by the computer to recognize the user's handwriting.