Systems and methods for printing sensor circuits on a sensor mat for a steering wheel

• US 10,114,513 B2
• Filed: 06/02/2015
• Issued: 10/30/2018
• Est. Priority Date: 06/02/2014
• Status: Active Grant

• Current Assignee: Joyson Safety Systems Acquisition, LLC (Ningbo Junsheng Investment Group Co., Ltd.)
• Original Assignee: Joyson Safety Systems Acquisition, LLC (Ningbo Junsheng Investment Group Co., Ltd.)
• Inventors: Staszak, Erick, Van'tZelfde, Dwayne, Lisseman, Jason
• Primary Examiner(s): He, Amy
• Application Number:
  US14/728,366
• Publication Number:
  US 20150344060A1
• Time in Patent Office: 1,246 Days
• Field of Search: 345173, 345174, 324658, 324663
• CPC Class Codes: G01N 27/041 of a solid body
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: G06F 3/0488 using a touch-screen or digitiser, e.g. input of commands through traced gestures
• CPC Class Codes: G06F 3/04883 for inputting data by handwriting, e.g. gesture or text
• CPC Class Codes: H03K 17/9622 using a plurality of detectors, e.g. keyboard
• CPC Class Codes: H03K 2217/960755 Constructional details of capacitive touch and proximity switches
• CPC Class Codes: H03K 2217/960765 Details of shielding arrangements

Abstract

Systems and methods of printing sensor loops on a sensor mat for use in a steering wheel are disclosed herein. For example, the sensor mat may include a base substrate, one or more printed sensing loops, and an insulating material. The printed sensing loops are made with conductive ink that is disposed upon the base substrate or the insulating layer from a print head and adheres thereto. These sensor mats are versatile with respect to the type of base substrate and insulating materials that may be used, the shape of the sensing loops, and the area each loop may occupy. Shielding loop(s) may also be printed adjacent the sensing loop(s). This configuration allows shielding for the sensing loops as part of the sensing mat, which may reduce the thickness of the steering wheel rim and manufacturing and installation times.

Claims

1. A sensor mat configured for being disposed around a steering wheel frame, the sensor mat comprising:

a base substrate supporting at least one shielding circuit, at least one sensing circuit, and a plurality of layers of insulating material, wherein the layers of insulating material define a plurality of surfaces in the sensor mat, and wherein the layers are stacked about an axis extending from the base substrate and through the plurality of surfaces;

one or more of the sensing circuits printed with conductive ink onto one of the plurality of surfaces of the insulating material;

one or more shielding circuits printed with the conductive ink onto another of the surfaces of insulating material within the sensor mat,

wherein the shielding circuits and the sensing circuits are configured in corresponding pairs of one shielding circuit and one sensing circuit, wherein the shielding circuits overlap at least one area within the plurality of surfaces of the insulating material on which a respective sensing circuit is printed and such that the shielding circuits and the sensing circuits are separated by at least one of the layers of the insulating material.

2. The sensor mat of claim 1, wherein the base substrate comprises another insulating material and at least one of the sensing circuits or at least one of the shielding circuits is printed onto the base substrate.

3. The sensor mat of claim 1, wherein the plurality of layers of insulating material comprises first and second layers of insulating material and the sensor mat further comprises:

the one or more shielding circuits are printed with the conductive ink onto the first layer of the insulating material, and

the second layer of the insulating material disposed over the one or more shielding circuits, wherein the one or more shielding circuits are disposed between the first layer of the insulating material and the second layer of the insulating material.

4. The sensor mat of claim 3, wherein:

the one or more sensing circuits comprise a first sensing circuit and a second sensing circuit and the one or more shielding circuits comprise a first shielding circuit and a second shielding circuit, and

the first shielding circuit is disposed adjacent the first sensing circuit and the second shielding circuit is disposed adjacent the second sensing circuit,

wherein each sensing circuit is a discrete sensing circuit and each shielding circuit is a discrete shielding circuit.

5. The sensor mat of claim 3, wherein:

the one or more sensing circuits comprise a first sensing circuit and a second sensing circuit and the one or more shielding circuits comprise a first shielding circuit, wherein each sensing circuit is a discrete sensing circuit, and

the first shielding circuit is disposed adjacent the first and second sensing circuits.

6. The sensor mat of claim 3, further comprising one or more shielding feed traces printed with conductive ink onto the first insulating material, each shielding feed trace extending from a corresponding shielding circuit toward an edge of the first insulating material.

7. The sensor mat of claim 2, further comprising one or more sensor return traces printed with conductive ink onto the base substrate and extending from a corresponding sensing circuit toward an edge of the base substrate.

8. The sensor mat of claim 1, wherein the plurality of layers of insulating material comprises first, second, and third layers of insulating material, and the one or more shielding circuits are printed with conductive ink onto the second layer of the insulating material disposed on the base substrate, wherein the third layer of the insulating material is disposed over the one or more shielding circuits and the one or more sensing circuits are printed onto the third layer of the insulating material, wherein the one or more shielding circuits are disposed between the second layer and third layer of the insulating material.

9. The sensor mat of claim 1, wherein the conductive ink comprises one or more of the following:

silver, carbon, carbon nanotube, graphene, zinc, nickel, tin or copper.

10. The sensor mat of claim 9, wherein the conductive ink further includes a polymer additive to affect a resistance of the ink.

11. The sensor mat of claim 1, wherein the conductive ink is capable of withstanding elongation up to about 10%.

12. The sensor mat of claim 11, wherein the base substrate is capable of elongating at least about 20%.

13. The sensor mat of claim 11, wherein the conductive ink is printed in a cross hatch or zigzag pattern.

14. The sensor mat according to claim 1, wherein the base substrate comprises a polymer film and a total thickness of the sensor mat is between about 60 microns to about 185 microns.

15. The sensor mat according to claim 1, wherein the base substrate is an underside of a leather skin configured for being installed around at least a portion of the steering wheel frame rim, and an opposite side of the underside of the leather skin is an outermost layer around the steering wheel frame rim.

16. The sensor mat of claim 1, wherein the ink is printed adjacent the base substrate in a pattern selected from one or more of the following:

cross-hatch, zigzag, grid, spiral, or solid area.

17. The sensor mat of claim 1, wherein the base substrate comprises one of the following:

a polymer foam, a polymer film, leather, vinyl, felt, or non-woven material.

18. A system for hand sensing in a steering wheel comprising:

a base substrate supporting at least one shielding circuit, at least one sensing circuit, and a plurality of layers of insulating material, wherein the layers of insulating material define a plurality of surfaces in a sensor mat, and wherein the layers are stacked about an axis extending from the base substrate and through the plurality of surfaces;

one or more of the sensing circuits printed with conductive ink onto one of the plurality of surfaces of the insulating material;

one or more shielding circuits printed with the conductive ink onto another of the surfaces of the insulating material within the sensor mat,

wherein the shielding circuits and the sensing circuits are configured in corresponding pairs of one shielding circuit and one sensing circuit, wherein the shielding circuits overlap at least one area within the plurality of surfaces of the insulating material on which a respective sensing surface is printed and such that the shielding circuits and the sensing circuits are separated by at least one of the layers of the insulating material;

wherein the sensing circuits and the shielding circuits comprise respective return traces extending across the respective one of the plurality of surfaces and another of the surfaces of the insulating material;

and

an electronic control unit in communication with the sensor mat via the return traces, wherein the electronic control unit comprises;

a processor, and

a power source,

wherein the processor is configured for receiving a signal from at least one of the one or more sensing circuits and determining an indication associated with the signal.

19. The system of claim 18, wherein the indication is selected from one of the following:

a touch, a tap, hold, swipe, or combination thereof.

20. The system of claim 18, wherein the one or more sensing circuits are printed onto the base substrate.

21. The system of claim 18, wherein the plurality of layers of insulating material comprises first, second, and third layers of the insulating material with the first layer of the insulating material connected to the base substrate, and the one or more shielding circuits are printed with conductive ink onto the second layer of the insulating material disposed on the base substrate, and wherein a third layer of insulating material is disposed over the one or more shielding circuits, and the one or more sensing circuits are printed onto the third layer of insulating material.

22. The system of claim 18, further comprising a corresponding shielding feed trace printed with conductive ink adjacent the base substrate, each shielding feed trace extending from a corresponding shielding circuit toward an edge of the base substrate.

23. The system of claim 22, further comprising a shielding feed wire connected to each shielding feed trace, the shielding feed wire extending between the respective shielding feed trace and the electronic control unit, wherein the processor is configured for instructing the power source to selectively generate a voltage signal through the one or more shielding circuits via the shielding feed wires and the shielding feed traces.

24. The system of claim 18, wherein the one or more shielding circuits are printed with conductive ink adjacent the base substrate and a corresponding shielding feed wire is connected to each shielding circuit, the shielding feed wire extending between the respective shielding circuit and the electronic control unit, wherein the processor is configured for instructing the power source to selectively generate a voltage signal through the one or more shielding circuits via the shielding feed wires.

25. The system of claim 18, further comprising one or more sensor return traces printed with conductive ink adjacent the base substrate, each sensor return trace corresponding to one of the one or more sensing circuits and extending from the respective sensor circuit toward an edge of the base substrate.

26. The system of claim 25, further comprising a sensor return wire extending between each sensor return trace and the electronic control unit, wherein the signal received from at least one of the sensing circuits is received by the processor via the sensor return wire and the sensor return trace.

27. The system of claim 18, further comprising a sensor return wire extending between each sensing circuit and the electronic control unit, wherein the signal received from at least one of the sensing circuits is received by the processor via the sensor return wire.

28. The system of claim 18, wherein the base substrate is a leather skin, and the sensing circuits are printed adjacent an underside of the leather skin, the leather skin is configured to be installed around the steering wheel frame rim, and an outer side of the leather skin opposite the underside is an outermost layer of the steering wheel frame rim.

29. The system of claim 18, wherein a polymeric foam material is disposed between at least a portion of the base substrate and an outermost skin disposed around the steering wheel frame rim.

30. The system of claim 18, wherein a polymeric foam material is disposed between at least a portion of the base substrate and the steering wheel frame rim.

31. A sensor mat configured for being disposed around a steering wheel frame, the sensor mat comprising:

sensor mat layers defined by a base substrate supporting a plurality of layers of insulating materials thereon;

a plurality of sensing circuits printed with conductive ink on respective surfaces of the sensor mat layers;

one or more shielding circuits printed with the conductive ink on at least one other surface of the sensor mat layers, wherein the other surface is not printed with a sensing circuit;

wherein at least one of the sensing circuits and a corresponding one of the shielding circuits are at least partially aligned along an axis extending from the base substrate and through the plurality of layers of insulating materials;

at least a portion of one of the layers of insulating material separating corresponding pairs of at least one of the sensing circuits and the corresponding one of the shielding circuits;

wherein the conductive ink exhibits an elongation characteristic sufficient to withstand stretching the sensor mat without breaking any circuits when wrapping the sensor mat around a rim of the steering wheel, and wherein the elongation characteristic is expressed as a percentage of elongation relative to a reference force stretching the conductive ink printed on a respective sensor mat layer.

32. A sensor mat according to claim 31, wherein the base substrate exhibits a corresponding elongation characteristic to withstand the stretching of the sensor mat without tearing the base substrate when wrapping the sensor mat around the rim of the steering wheel.

33. A sensor mat according to claim 32, wherein a maximum elongation characteristic of the base substrate overlaps a minimum elongation characteristic of the conductive ink.