Feedback mouse

Claim 1

In the combination of a display system including a display screen, a video display controller and an input mouse including means cooperable with the display controller for moving a cursor on the display screen in response to motion of the mouse, the improvement which comprises a resistive feedback system detectable by the user of the mouse including: electromagnetic means for producing an operator-discernible resistance to the motion of the mouse, as the cursor on the screen, whose motion is controlled by said mouse, moves across predetermined locations on the screen of said display, and control signal generating circuitry in the display controller for producing a control signal when the cursor reaches predetermined locations on the screen, and wherein the surface over which the mouse is to move is non-specific and the means for sensing motion of the mouse includes a spherical ball contacting said surface and being rotatable when said mouse is moved and two pickup wheels in frictional contact with said ball at a location remote from said surface for detecting motion of the ball along the X and Y axes thereof, the electromagnetic means for producing resistance to the motion of the mouse comprising electromagnetic braking elements physically connected to resist axial movement of the X and Y frictional pickup wheels when energized, and brake energization circuitry actuable in response to said control signal for selectively energizing said electromagnetic braking elements, said control signal generating circuitry further including, means for producing said control signal as a digital "magnetization function" signal of a magnitude proportional to the desired resistance to motion of the mouse as it approaches a predetermined location on the screen, a digital-to-analog converter (D/A) for producing an analog signal from said digital magnetization function, and a magnet driver circuit comprising: an operational amplifier (op-amp) connected to the output of the D/A converter, a power transistor, which supplies energization current to the magnet under control of the op-amp, a protection diode connected in parallel with the electro-magnet, and a sense resistor in the emitter circuit of the power transistor for providing control information to said op-amp.