Patent ID: 6218632
Filing Date: 2001-04-17
Classification: G01G

Abstract:
A weight sensing apparatus for a vehicle seat comprising:a differential capacitor including:a first capacitor including first and second opposed plate assemblies;a second capacitor including a third plate assembly and said second plate assembly;said second plate assembly being interposed between said first and third plate assemblies and axially adjoining said first capacitor to said second capacitor;each plate assembly including a conductive plate, said conductive plate of said first plate assembly extending parallel to and being fixed relative to said conductive plate of said third plate assembly, said conductive plate of said second plate assembly extending parallel to and being moveable in an axial direction relative to said first and third plate assemblies in response to a load being applied to the vehicle seat;each plate assembly having a plurality of elongated members which extend in a substantially axial direction, each elongated member being at least partially formed from a conductive member which is electrically connected to said conductive plate of the respective plate assembly;said plurality of elongated members of said first and third plate assemblies extending toward said second plate assembly;said second plate assembly having a plurality of elongated members extending toward said first plate assembly and a plurality of elongated members extending toward said third plate assembly, said plurality of elongated members extending from said second plate assembly terminating in gaps created by said elongated members of said first and third plate assemblies, said plurality of elongated members of said second plate assembly being movable relative to said plurality of elongated members of said first and third plate assemblies;a source of alternating electrical energy which provides electrical energy to said differential capacitor; andan output circuit electrically connected with said differential capacitor which provides an output signal indicative of the load applied to said weight sensing apparatus, the output signal of said output circuit varying as a function of the capacitance of both said first capacitor and said second capacitor.