Patent ID: 7701201

Claim:
An inductive switch apparatus, comprising: a sensor unit, the sensor unit comprising: a printed circuit board, at least first and second sensor coils printed on the printed circuit board in planar configurations and configured to circumscribe areas so as to not overlap each other or circumscribed areas of other coils in a direction normal to planes of said first and second sensor coils, said first and second sensor coils respectively having first and second self-inductances, and at least one conductive actuator element configured and mounted so as to be adjustably superimposable to different extents over the first and second sensor coils such that a change in said superimposition extent produces changes in said first and second self-inductances, and an evaluation circuit to independently drive said at least first and second sensor coils with first and second signals conductively applied to said first and second coils and indicative of said first and second self-inductances, and said evaluation circuit having a switching function triggered by inductance changes of said first and second self-inductances relative to each other as determined by evaluating said first and second signals as they are conductively applied to said first and second coils.