Method and apparatus for providing an integrated membrane switch and capacitive sensor

• US 6,943,705 B1
• Filed: 09/19/2002
• Issued: 09/13/2005
• Est. Priority Date: 05/03/2002
• Status: Expired due to Fees

• Current Assignee: Synaptics Incorporated
• Original Assignee: Synaptics Incorporated
• Inventors: Bolender, Robert James, Cheng, Wendy H. W.
• Primary Examiner(s): WONG, ALBERT KANG
• Application Number:
  US10/251,563
• Time in Patent Office: 1,090 Days
• Field of Search: 178/19.03, 345/173, 345/174, 341/20, 341/33, 335/205, 338/13, 200/600
• US Class Current: 341/33
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• CPC Class Codes: H01H 2239/006 Containing a capacitive switch or usable as such
• CPC Class Codes: H03K 17/962 Capacitive touch switches
• CPC Class Codes: H03K 2217/94015 Mechanical, e.g. by displacement of a body, a shielding element, or a magnet, in or out of the sensing area
• CPC Class Codes: H03K 2217/960765 Details of shielding arrangements

Abstract

A circuit assembly for providing a switch sensor and a capacitive sensor. The circuit assembly has a first pattern of conductive material in a first plane and a second pattern of conductive material in a second plane. An insulating member in an intermediate plane separates the first and second patterns. In a switch sensor area, the insulating member has openings to allow a first conductive element in the first pattern to contact a second conductive element in the second pattern responsive a force being applied to the first conductive element. In the capacitive sensor area, the insulating member maintains spacing between conductive material in the first and second patterns. The circuit assembly also includes a preventative capacitance configuration that limits non-intentional capacitive coupling in the capacitive sensor area.

Claims

1. A sensor circuit assembly comprising:

a switch sensor area having a first conductive element in conductive material of a first pattern oriented in a first plane, a second conductive element in conductive material of a second pattern oriented in a second plane substantially parallel to said first plane, and an insulating member that allows electrical contact between said first conductive element and said second conductive element responsive to force being applied to said first conductive element;

a capacitive sensor area having a portion of a first layer of conductive material in a first one of a group consisting of said first pattern and said second pattern; and

a preventative capacitance configuration that limits non-intentional capacitive coupling to said portion of said first layer in said capacitive sensor area.

2. The circuit assembly of claim 1 wherein said preventative capacitance configuration comprises:

a conductor held at a substantially constant voltage in said first one of said first and second patterns between said switch sensor area and said capacitive sensor area to reduce reception of signals from said switch sensor area in said capacitive sensor area.

3. The circuit assembly of claim 1 wherein said preventative capacitance configuration includes said switch sensor area and said capacitive sensor area being spaced sufficiently apart to reduce reception of signals from said switch sensor area in said capacitive sensor area.

4. The circuit assembly of claim 1 further comprising:

a first plurality of electrodes in said capacitive sensor area defined in said conductive material of said first layer aligned substantially along a first axis.

5. The circuit assembly of claim 4 further comprising:

a first plurality of conductors connecting said first plurality of electrodes to sensor electronics.

6. The circuit assembly of claim 5 wherein said first plurality of conductors comprises:

a plurality of traces of conductive material within said first layer.

7. The circuit assembly of claim 5 wherein said preventative capacitance configuration includes at least one of said first plurality of conductors being routed around areas proximate to positions of other objects in the environment.

8. The circuit assembly of claim 5 wherein said preventative capacitance configuration comprises:

shielding between other objects in the environment and said first plurality of conductors to reduce non-intended capacitive coupling between said first plurality of conductors and said other objects.

9. The circuit assembly of claim 5 wherein said preventative capacitance configuration comprises:

a casing enclosing said first plurality of conductors, said casing defining an air gap between an inner surface of said casing and said first plurality of conductors to reduce non-intended capacitive coupling between other objects in the environment and said first plurality of conductors.

10. The circuit assembly of claim 5 wherein said preventative capacitance configuration comprises:

a conductor held at a substantially constant voltage between at least a portion of said first layer and other objects in the environment to reduce non-intended capacitive coupling between said other objects in the environment and said first plurality of conductors.

11. The circuit assembly of claim 1 further comprising:

a portion of a second layer of conductive material in said capacitive sensor area.

12. The circuit assembly of claim of 11 further comprising:

a third pattern of conductive material including said second layer of said conductive material, wherein said third pattern is in a third plane substantially parallel to said first plane and said second plane.

13. The circuit assembly of claim 12 wherein a second one of a group consisting of said first pattern and said second pattern includes said third pattern of conductive material.

14. The circuit assembly of claim 13 wherein said insulating member maintains separation between said first pattern and said second pattern in said capacitive sensor area.

15. The circuit assembly of claim 11 wherein a position of said conductive input object with respect to said capacitive sensor area is determined without contact between said conductive material of said first layer and said conductive material of said second layer in said capacitive sensor area.

16. The circuit assembly of claim 11 wherein said position of said conductive input object is determined without substantial relative movement of said conductive material of said first layer and said conductive material of said second layer in said capacitive sensor area.

17. The circuit assembly of claim 11 wherein said preventative capacitance configuration limits non-intentional capacitive coupling to said second layer in said capacitive sensor area.

18. The circuit assembly of claim 17 wherein said preventative capacitance configuration comprises said insulating member having an opening in said capacitive sensor area to reduce capacitive coupling between said first layer of conductive material and said second layer of conductive material.

19. The circuit assembly of claim 17 wherein said preventative capacitance configuration comprises:

shielding between at least a portion of said conductive material in said first layer and at least a portion of said conductive material in said second layer to reduce capacitive coupling between said conductive material in said first layer and said conductive material in said second layer.

20. The circuit assembly of claim 19 wherein said shielding comprises a conductor held at a substantially constant voltage.

21. The circuit assembly of claim 19 wherein said shielding is air gaps defined by openings through said insulating member.

22. The circuit assembly of claim 17 further comprising:

a first plurality of electrodes in said capacitive sensor area defined in said conductive material of said first layer aligned substantially along a first axis; and

a second plurality of electrodes in said capacitive sensor area defined in said conductive material of said second layer and aligned substantially along a second axis nonparallel to said first axis.

23. The circuit assembly of claim 22 further comprising:

a first plurality of conductors connecting said first plurality of electrodes to capacitive sensor electronics; and

a second plurality of conductors connecting said second plurality of electrodes to said capacitive sensor electronics.

24. The circuit assembly of claim 23 wherein said first plurality of conductors comprises:

a first plurality of traces of conductive material within said first layer defining said first plurality of conductors.

25. The circuit assembly of claim 23 wherein said second plurality of conductors comprises:

a second plurality of traces of conductive material within said second layer defining said second plurality of conductors.

26. The circuit assembly of claim 23 wherein said preventative capacitance configuration comprises:

a conductor held at a substantially constant voltage between at least a portion of said second layer and other objects in the environment to reduce non-intended capacitive coupling between said other objects in the environment and said second plurality of conductors.

27. The circuit assembly of claim 23 wherein said preventive capacitance configuration comprises:

shielding between at least part of said first plurality of conductors and positions of other objects in the environment to reduce non-intended capacitive coupling effects between said other objects and said first plurality of conductors.

28. The circuit assembly of claim 23 wherein said preventive capacitance coupling configuration comprises:

shielding between at least a part of said second plurality of conductors and positions of other objects in the environment to reduce non-intended coupling effects of between said other objects and said second plurality of conductors.

29. The circuit assembly of claim 23 wherein said preventative capacitance configuration comprises:

at least one of said first plurality of conductors being routed around areas corresponding to regions of said casing proximate to positions of other objects in the environment.

30. The circuit assembly of claim 23 wherein preventative capacitance configuration comprises:

at least one of said second plurality of conductors being routed around areas corresponding to regions of said casing proximate other objects in the environment.

31. The circuit assembly of claim 23 wherein said preventative capacitance configuration comprises:

a casing enclosing said second plurality of conductors, said casing defining an air gap between an inner surface of said casing and said second plurality of conductors to reduce non-intended capacitive coupling between other objects in the environment and said second plurality of conductors.

32. The circuit assembly of claim 1 wherein said preventative capacitance configuration comprises:

a casing enclosing said switch sensor area and said capacitive sensor area.

33. The circuit assembly of claim 32 further comprising:

a bezel in a first surface of said casing demarking said capacitive sensor area to said user.

34. The circuit assembly of claim 33 wherein said bezel comprises an opening in said casing.

35. The circuit assembly of claim 33 wherein said bezel comprises a textured region over said capacitive sensor area.

36. The circuit assembly of claim 33 further comprising:

a brace member proximate to said bezel for clamping said first layer in said capacitive sensor area in place against a second surface inside said casing.

37. The circuit assembly of claim 36 further comprising:

a localized clamping region of said brace member proximate to said capacitive sensor area to hold said first layer in said capacitive sensor area in place against said bezel.

38. The circuit assembly of claim 33 further comprising:

a brace member for holding said first layer of said capacitive sensor area in place against said bezel.

39. The circuit assembly of claim 1 further comprising:

a registration member that secures a position of said first pattern with respect to said second pattern.

40. The circuit assembly of claim 39 wherein said registration member secures said insulating member in place with respect to said first pattern and said second pattern.

41. The circuit assembly of claim 39 wherein said registration member comprises:

a coupling of said first pattern and said second pattern that holds said first pattern, and said second pattern substantially in place with respect to one another.

42. The circuit assembly of claim 41 wherein said coupling provides stiffness to said circuit assembly.

43. The circuit assembly of claim 41 wherein said coupling is a heat staking connecting said first pattern and said second pattern.

44. The circuit assembly of claim 41 wherein said coupling comprises:

an adhesive connecting substrates of said first pattern and said second pattern.

45. The circuit assembly of claim 41 wherein said coupling comprises:

a substrate having said first pattern on a first side and said second pattern on a second side.

46. The circuit assembly of claim 39 wherein said registration member comprises:

a nib on a first surface of said insulating member; and

an opening through a substrate of said first pattern that mates to and fits over said nib to secure said first pattern in place with respect to said nib.

47. The circuit assembly of claim 46 wherein said registration member further comprises:

a nib on a second surface of said insulating member; and

an opening through a substrate of said second pattern that mates to and fits over said nib to secure said second pattern in place with respect to said nib.

48. The circuit assembly of claim 39 wherein said registration member comprises:

a structural member on an inner surface of a casing that mates to and fits in an opening through said first pattern and an opening through said second pattern.

49. The circuit assembly of claim 1 further comprising:

a layer of textured material over said capacitive sensor area.

50. The circuit assembly of claim 49 wherein said layer of textured material provides an aesthetic feeling of touch to said user.

51. The circuit assembly of claim 49 wherein said layer of textured material stiffens said circuit assembly.

52. The circuit assembly of claim 49 wherein said textured material is a polyester material.

53. A method for configuring a sensor circuit assembly comprising:

defining a switch sensor area having a first conductive element in conductive material of a first pattern oriented in a first plane, a second conductive element in conductive material of a second pattern oriented in a second plane substantially parallel to said first plane, and an insulating member that allows electrical contact between said first conductive element and said second conductive element responsive to force being applied to said first conductive element;

defining a capacitive sensor area having a portion of a first layer of conductive material in a first one of a group consisting of said first pattern and said second pattern; and

limiting non-intentional capacitive coupling to said portion of said first layer in said capacitive sensor area.

54. The method of claim 53 wherein said step of limiting non-intentional coupling comprises:

positioning a conductor held at a substantially constant voltage in said first one of said first and second patterns between said switch sensor area and said capacitive sensor area to reduce reception of signals from said switch sensor area in said capacitive sensor area.

55. The method of claim 53 wherein step of limiting non-intentional capacitive coupling includes spacing said switch sensor area and said capacitive sensor area sufficiently apart to reduce reception of signals from said switch sensor area in said capacitive sensor area.

56. The method of claim 53 further comprising:

defining a first plurality of electrodes in said capacitive sensor area in said conductive material of said first layer aligned substantially along a first axis.

57. The method of claim 56 further comprising:

connecting said first plurality of electrodes to sensor electronics with a first plurality of conductors.

58. The method of claim 57 wherein said step of connecting comprises:

defining a plurality of traces of conductive material within said first layer to act as a first plurality of conductors.

59. The method of claim 57 wherein said step of limiting said non-intentional capacitive coupling comprises:

routing at least one of said first plurality of conductors around areas proximate to positions of other objects in the environment.

60. The method of claim 57 wherein said step of limiting non-intentional capacitive coupling comprises:

shielding said first plurality of conductors from other objects in the environment to reduce non-intended capacitive coupling between said first plurality of conductors and said other objects.

61. The method of claim 57 wherein said step of limiting said non-intentional capacitive coupling comprises:

enclosing said first plurality of conductors in a casing defining an air gap between an inner surface of said casing and said first plurality of conductors to reduce non-intended capacitive coupling between other objects in the environment and said first plurality of conductors.

62. The method of claim 57 wherein said step of limiting said non-intentional capacitive coupling comprises:

positioning a conductor held at a substantially constant voltage between at least a portion of said first layer and other objects in the environment to reduce non-intended capacitive coupling between said other objects in the environment and said first plurality of conductors.

63. The method of claim 53 further comprising:

defining a portion of a second layer of conductive material in said capacitive sensor area.

64. The method of claim of 63 wherein a third pattern of conductive material includes said second layer of said conductive material, wherein said third pattern is in a third plane substantially parallel to said first plane and said second plane.

65. The circuit assembly of claim 63 wherein a second one of a group consisting of said first pattern and said second pattern includes said third pattern of conductive material, said method further comprising:

maintaining separation between said first pattern and said second pattern in said capacitive sensor area with said insulating member.

66. The method of claim 63 wherein a position of said conductive input object with respect to said capacitive sensor area is determined without contact between said conductive material of said first layer and said conductive material of said second layer in said capacitive sensor area.

67. The method of claim 63 wherein said position of said conductive input object is determined without substantial relative movement of said conductive material of said first layer and said conductive material of said second layer in said capacitive sensor area.

68. The method of claim 63 said step of limiting said non-intentional capacitive coupling further comprises:

limiting non-intentional capacitive coupling to said second layer in said capacitive sensor area.

69. The method of claim 68 wherein said step of limiting said non-intentional capacitive coupling comprises:

defining an opening through said insulating member in said capacitive sensor area to reduce capacitive coupling between said first layer of conductive material and said second layer of conductive material.

70. The method of claim 68 wherein said step of limiting said non-intentional capacitive coupling comprises:

shielding at least a portion of said conductive material in said first layer from at least a portion of said conductive material in said second layer to reduce capacitive coupling between said conductive material in said first layer and said conductive material in said second layer.

71. The method of claim 63 further comprising:

defining a first plurality of electrodes in said capacitive sensor area defined in said conductive material of said first layer aligned substantially along a first axis; and

defining a second plurality of electrodes in said capacitive sensor area defined in said conductive material of said second layer and aligned substantially along a second axis nonparallel to said first axis.

72. The method of claim 71 further comprising:

connecting said first plurality of electrodes to capacitive sensor electronics with a first plurality of conductors; and

connecting said second plurality of electrodes to said capacitive sensor electronics with a second plurality of conductors.

73. The method of claim 72 wherein said step of connecting with said second plurality of conductors comprises:

defining a second plurality of traces of conductive material within said second layer defining said second plurality of conductors.

74. The method of claim 72 wherein said step of limiting said non-intentional capacitive coupling comprises:

positioning a conductor held at a substantially constant voltage between at least a portion of said second layer and other objects in the environment to reduce non-intended capacitive coupling between said other objects in the environment and said second plurality of conductors.

75. The method of claim 72 wherein said step of limiting said non-intentional capacitive coupling comprises:

shielding at least part of said first plurality of conductors from other objects in the environment to reduce non-intended capacitive coupling effects between said other objects and said first plurality of conductors.

76. The method of claim 72 wherein said step of limiting said non-intentional capacitive coupling comprises:

shielding at least a part of said second plurality of conductors from other objects in the environment to reduce non-intended coupling effects of between said other objects and said second plurality of conductors.

77. The method of claim 72 wherein said step of limiting said non-intentional capacitive coupling comprises:

routing at least one of said first plurality of conductors around areas corresponding to regions of said casing proximate to positions of other objects in the environment.

78. The method of claim 72 wherein said step of limiting said non-intentional capacitive coupling comprises:

routing at least one of said second plurality of conductors around areas corresponding to regions of said casing proximate other objects in the environment.

79. The method of claim 72 wherein said step of limiting said non-intentional capacitive coupling comprises:

enclosing said second plurality of conductors in a casing defining an air gap between an inner surface of said casing and said second plurality of conductors to reduce non-intended capacitive coupling between other objects in the environment and said second plurality of conductors.

80. The method of claim 53 wherein said step of limiting said non-intentional capacitive coupling comprises:

enclosing said switch sensor area and said capacitive sensor area in a casing.

81. The method of claim 80 further comprising:

defining a bezel in a first surface of said casing demarking said capacitive sensor area to said user.

82. The method of claim 81 wherein said bezel comprises an opening in said casing.

83. The circuit assembly of claim 81 wherein defining said bezel comprises:

placing a textured region over said capacitive sensor area.

84. The method of claim 81 further comprising:

clamping said first layer in said capacitive sensor area in place against a second surface inside said casing with a brace member proximate said bezel.

85. The method of claim 53 further comprising:

securing a position of said first pattern with respect to said second pattern.

86. The method of claim 85 further comprising:

securing said insulating member in place with respect to said first pattern and said second pattern.

87. The method of claim 85 wherein said step of securing comprises:

coupling said first pattern to said second pattern to hold said first pattern, and said second pattern substantially in place with respect to one another.

88. The method of claim 53 further comprising:

inserting a layer of textured material over said capacitive sensor area.