Patent ID: 7116096

Claim:
Apparatus comprising: a tone ring rotatable in response to forward or reverse movement of a vehicle, said tone ring having a pattern of excitation including amplitude variations that is indicative of the direction of rotation of said tone ring; and a sensor having an output responsive to rotation of said tone ring past said sensor, said sensor having a first output responsive to the amplitude variations produced by rotation of said tone ring in a first direction, said sensor having a second output responsive to the amplitude variations produced by rotation of said tone ring in a second direction, said second output being different from said first output; said first and second outputs for use in activating a vehicle function that is indicative of a reverse direction of movement of the vehicle; wherein the tone ring includes a plurality of teeth that are of the same width and are equally spaced along the tone ring with equal spaces between them, a first plurality of the teeth being shorter than a second plurality of the teeth thereby producing an output of different amplitudes in the sensor.