Apparatus and method of producing a sensing substrate
An occupant or object sensing system in a vehicle includes electrical circuits for capacitive sensing and corresponding circuits shielding the sensing system from interference. A sensing circuit and a shielding circuit may be printed by screen printing with conductive ink on opposite sides of a non-conductive substrate. The substrate is a plastic film or other fabric that has an elastic memory structure that is resilient to stretching. The conductive inks used to print circuits onto the substrate have a similar resilience to stretching such that the substrate and the circuits thereon can be subject to deforming forces without breaking the printed circuits. The substrate may be covered with a carbon polymer layer to provide alternative conductive paths that enable fast recovery for conduction in the presence of any break in the printed conductive traces on the substrate.
1 . A substrate comprising:
a non-conductive sheet having a first face and a second face;
respective conductive traces connected to the first face and the second face, the respective conductive traces defining respective electrical circuits having structural continuity without a break in the respective conductive traces on the first face or the second face;
wherein said non-conductive sheet and said conductive traces each comprise flexible compositions that stretch and contract in conjunction with one another and with the structural continuity of the conductive traces being maintained in the presence of deforming forces upon the non-conductive sheet.
2 . A substrate according to claim 1 , wherein said sheet and said conductive traces are configured to withstand deforming forces that stretch a dimension of said sheet in any direction by an amount between 2 percent and 10 percent.
3 . A substrate according to claim 1 ,
wherein said conductive traces define a first pattern on said first face and a second pattern on said second face,
wherein said sheet comprises an elastic memory sheet.
4 . A substrate according to claim 1 , wherein said deforming forces comprise at least one of tensile forces, compressive forces, shear forces, and combinations thereof.
5 . A substrate according to claim 1 , wherein said conductive traces comprise a solidified derivative structure of a fluidic and printable composition.
6 . A substrate according to claim 5 , wherein said fluidic and printable composition is a conductive ink.
7 . A substrate according to claim 5 , wherein said solidified derivative structure is a stretchable conductive ink.
8 . A substrate according to claim 1 , wherein said non-conductive sheet comprises a film.
9 . A substrate according to claim 1 , wherein said non-conductive sheet comprises a plastic film.
10 . A substrate according to claim 9 , wherein said plastic film is selected from the group consisting of PET, PEN, PI, and combinations thereof.
11 . A substrate according to claim 9 , wherein said plastic film comprises a thermoplastic polyurethane film.
12 . A substrate according to claim 9 , wherein said plastic film is impervious to a conductive ink used to form the conductive traces.
13 . A substrate according to claim 1 , wherein said non-conductive sheet is a fabric.
14 . A substrate according to claim 13 , wherein said fabric comprises at least one of woven fabrics, non-woven fabrics, and combinations thereof.
15 . A substrate according to claim 13 , wherein said fabric has a surface finish that enables screen printing.
16 . A substrate according to claim 15 , wherein said surface finish is resistant to the fabric absorbing a conductive ink used to form the respective traces.
17 . A substrate used in the manufacture of vehicle components, comprising:
a single non-conductive base sheet having a first face and a second face,
respective conductive traces on the first face and the second face with at least one of the respective conductive traces defining an electrical circuit in a mesh pattern having contact between adjacent traces defining the electrical circuit with structural continuity on the first face or the second face;
wherein said non-conductive base sheet and said conductive traces each comprise flexible compositions allowing the base sheet and the conductive traces to stretch and contract in conjunction with one another and maintain electrical continuity of the conductive traces in the mesh pattern in the presence of deforming forces changing the shape of the substrate to correspond to a respective vehicle component.
18 . The substrate of claim 17 , wherein the shape of the substrate corresponds to a vehicle component selected from the group consisting of a vehicle seat, a seat belt, an A-pillar of the vehicle, a B-pillar of the vehicle, a steering wheel, a parking brake, a visor, a head rest, and a dash board of the vehicle.
19 . The substrate of claim 17 , wherein said shape is a molded shape of the respective vehicle component.
20 . The substrate of claim 17 , wherein a conductive trace on the first face comprises a shield circuit and a different conductive trace on the second face comprises a sensor circuit.