Resistive Touch Sensor System and Method

• US 20150091858A1
• Filed: 09/26/2014
• Published: 04/02/2015
• Est. Priority Date: 09/27/2013
• Status: Active Grant

• Current Assignee: Sensel, Inc.
• Original Assignee: Sensel, Inc.
• Inventors: Rosenberg, Ilya Daniel, Zarraga, John Aaron
• Granted Patent: US 9,465,477 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 2203/04103 Manufacturing, i.e. details related to manufacturing processes specially suited for touch sensitive devices
• CPC Class Codes: G06F 2203/04104 Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
• CPC Class Codes: G06F 2203/04106 Multi-sensing digitiser, i.e. digitiser using at least two different sensing technologies simultaneously or alternatively, e.g. for detecting pen and finger, for saving power or for improving position detection
• CPC Class Codes: G06F 3/04144 using an array of force sensing means position sensing using the local deformation of sensor cells G06F3/0447
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/041661 using detection at multiple resolutions, e.g. coarse and fine scanning; using detection within a limited area, e.g. object tracking window
• CPC Class Codes: G06F 3/0442 using active external devices, e.g. active pens, for transmitting changes in electrical potential to be received by the digitiser
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• 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: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Abstract

A resistive touch sensor system and method incorporating an interpolated sensor array is disclosed. The system and method utilize a touch sensor array (TSA) configured to detect proximity/contact/pressure (PCP) via a variable impedance array (VIA) electrically coupling interlinked impedance columns (IIC) coupled to an array column driver (ACD), and interlinked impedance rows (IIR) coupled to an array row sensor (ARS). The ACD is configured to select the IIC based on a column switching register (CSR) and electrically drive the IIC using a column driving source (CDS). The VIA conveys current from the driven IIC to the IIC sensed by the ARS. The ARS selects the IIR within the TSA and electrically senses the IIR state based on a row switching register (RSR). Interpolation of ARS sensed current/voltage allows accurate detection of TSA PCP and/or spatial location.

Claims

1. A resistive touch sensor system comprising:

(a) touch sensor array (TSA);

(b) array column driver (ACD);

(c) column switching register (CSR);

(d) column driving source (CDS);

(e) array row sensor (ARS);

(f) row switching register (RSR);

(g) analog to digital converter (ADC); and

(h) computing control device (CCD);

wherein

said TSA comprises a variable impedance array (VIA) comprising VIA columns and VIA rows;

said VIA comprises a first layer having a top side and a bottom side;

said first layer comprises a force sensing material;

said VIA comprises a second layer having a top side and a bottom side;

said second layer comprises exposed coplanar drive electrodes;

said second layer further comprises coplanar sense electrodes;

said VIA is configured to electrically couple a plurality of interlinked impedance columns (IIC) within said TSA with a plurality of interlinked impedance rows (IIR) within said TSA;

said IIC further comprises a plurality of individual column impedance elements (ICIE) electrically connected in series between said drive electrodes;

said IIR further comprises a plurality of individual row impedance elements (IRIE) electrically connected in series between said sense electrodes;

said ACD is configured to select said IIC within said TSA based on said CSR;

said ACD is configured to electrically drive said selected IIC using said CDS;

said CDS is configured to power one or more of said drive electrodes while driving one or more of said drive electrodes to ground potential;

said ARS is configured to select said IIR within said TSA based on said RSR while simultaneously driving one or more of said sense electrodes to ground potential;

said ADC is configured to sense the electrical state of said selected IIR and convert said electrical state to a sensed digital value (SDV);

said electrical state is determined by the sum of current contributions of variable impedance elements within said VIA, where the current contribution of each element is determined by a voltage divider formed between the columns of said VIA, a current divider formed between the rows of said via, and the state of the impedance element, to produce a sensed current for a given row-column intersection with said VIA; and

said CCD is configured to sample said SDV from said ADC at a plurality of positions within said TSA to form a touch sensor matrix (TSM) data structure.

2. The resistive touch sensor system of claim 1 wherein said drive electrodes reside on said top side of said second layer, said sense electrodes reside on said bottom side of said second layer, and vias interconnect said sense electrodes to conductive pads on said top side of said second layer.

3. The resistive touch sensor system of claim 1 wherein said sense electrodes reside on said top side of said second layer, said drive electrodes reside on said bottom side of said second layer, and vias interconnect said drive electrodes to conductive pads on said top side of said second layer.

4. The resistive touch sensor system of claim 1 wherein said sense electrodes comprise an upper surface and a lower surface, and said upper surface of said sense electrodes are planar.

5. The resistive touch sensor system of claim 1 wherein the row/column pitch of said drive electrodes and said sense electrodes is 1 mm.

6. The resistive touch sensor system of claim 1 wherein said drive electrodes and said sense electrodes form a rectangle pattern.

7. The resistive touch sensor system of claim 1 wherein said drive electrodes and said sense electrodes form an interdigitated finger pattern.

8. The resistive touch sensor system of claim 1 wherein said drive electrodes and said sense electrodes form a rectangle pattern with every other column flipped.

9. The resistive touch sensor system of claim 1 wherein said drive electrodes and said sense electrodes form an interdigitated finger pattern with every other column flipped.

10. The resistive touch sensor system of claim 1 wherein said drive electrodes and said sense electrodes form a diamond pattern.

11. The resistive touch sensor system of claim 1 wherein said drive electrodes and said sense electrodes form a non-rectangular force sensor array.

12. The resistive touch sensor system of claim 1 wherein said first layer comprises a thin layer having a high per-square resistance to bulk resistance ratio.

13. The resistive touch sensor system of claim 1 wherein said VIA comprises sensor elements having a resistance greater than that of the IIR impedances and the IIC impedances.

14. The resistive touch sensor system of claim 1 wherein said first layer comprises a force sensing layer that is segmented with segments aligning to force sensing elements within said VIA.

15. The resistive touch sensor system of claim 1 wherein said first layer comprises a polymer loaded with conductive particles.

16. The resistive touch sensor system of claim 1 wherein said first layer comprises a force sensing layer that is patterned.

17. The resistive touch sensor system of claim 1 wherein said first layer comprises a force sensing layer that is patterned with a random or pseudo-random pattern.

18. The resistive touch sensor system of claim 1 wherein said second layer comprises traces that further comprise a force sensing material.

19. The resistive touch sensor system of claim 1 wherein said first layer comprises a force sensing layer having material selected from a group consisting of:

conductive rubber;

conductive foam;

conductive plastic;

KAPTON®

loaded with conductive particles;

conductive ink;

a mixture of conductive particles with insulating particles; and

carbon particles mixed with a polymer.

20. The resistive touch sensor system of claim 1 wherein said second layer comprises conductive traces that are coated with gold plating.

21. The resistive touch sensor system of claim 1 wherein said second layer comprises conductive traces that are coated with an electroless nickel gold (ENIG) plating.

22. The resistive touch sensor system of claim 1 wherein said second layer comprises conductive traces that are coated with a screen printed carbon.

23. The resistive touch sensor system of claim 1 wherein said second layer comprises a rigid printed circuit board (PCB).

24. The resistive touch sensor system of claim 1 wherein said second layer comprises a rigid printed circuit board (PCB) comprising FR4 material.

25. The resistive touch sensor system of claim 1 wherein said second layer comprises a flexible printed circuit board (PCB).

26. The resistive touch sensor system of claim 1 wherein said second layer comprises a printed circuit board (PCB) formed using an additive printed electronics process.

27. The resistive touch sensor system of claim 1 wherein said second layer comprises mechanically drilled vias.

28. The resistive touch sensor system of claim 1 wherein said second layer comprises laser drilled vias.

29. The resistive touch sensor system of claim 1 wherein said second layer comprises filled vias.

30. The resistive touch sensor system of claim 1 wherein said second layer comprises vias formed by openings in a printed dielectric layer.

31. The resistive touch sensor system of claim 1 wherein said second layer comprises thin conductive bridges between said VIA columns.

32. The resistive touch sensor system of claim 1 wherein said second layer comprises thin conductive bridges between said VIA rows.

33. The resistive touch sensor system of claim 1 wherein said TSA comprises interpolation resistors further comprising discrete surface mount resistors.

34. The resistive touch sensor system of claim 1 wherein said TSA comprises interpolation resistors further comprising discrete surface mount resistors having an accuracy of 1% or better.

35. The resistive touch sensor system of claim 1 wherein said TSA comprises interpolation resistors further comprising laser trimmed resistors.

36. The resistive touch sensor system of claim 1 wherein said VIA is attached to a flexible display coated with a force sensing material (FSM) that forms said first layer.

37. A resistive touch sensor method configured to operate on a resistive touch sensor system comprising:

(a) touch sensor array (TSA);

(b) array column driver (ACD);

(c) column switching register (CSR);

(d) column driving source (CDS);

(e) array row sensor (ARS);

(f) row switching register (RSR);

(g) analog to digital converter (ADC); and

(h) computing control device (CCD);

wherein

said TSA comprises a variable impedance array (VIA) comprising VIA columns and VIA rows;

said VIA comprises a first layer having a top side and a bottom side;

said first layer comprises a force sensing material;

said VIA comprises a second layer having a top side and a bottom side;

said second layer comprises exposed coplanar drive electrodes;

said second layer further comprises coplanar sense electrodes;

said VIA is configured to electrically couple a plurality of interlinked impedance columns (IIC) within said TSA with a plurality of interlinked impedance rows (IIR) within said TSA;

said IIC further comprises a plurality of individual column impedance elements (ICIE) electrically connected in series between said drive electrodes;

said IIR further comprises a plurality of individual row impedance elements (IRIE) electrically connected in series between said sense electrodes;

said ACD is configured to select said IIC within said TSA based on said CSR;

said ACD is configured to electrically drive said selected IIC using said CDS;

said CDS is configured to power one or more of said drive electrodes while driving one or more of said drive electrodes to ground potential;

said ARS is configured to select said IIR within said TSA based on said RSR;

said ADC is configured to sense the electrical state of said selected IIR and convert said electrical state to a sensed digital value (SDV);

said ADC is configured to sense the voltage on one or more of said sense electrodes while simultaneously driving one or more of said sense electrodes to ground potential;

said electrical state is determined by the sum of current contributions of variable impedance elements within said VIA, where the current contribution of each element is determined by a voltage divider formed between the columns of said VIA, a current divider formed between the rows of said via, and the state of the impedance element, to produce a sensed current for a given row-column intersection with said VIA; and

said CCD is configured to sample said SDV from said ADC at a plurality of positions within said TSA to form a touch sensor matrix (TSM) data structure;

wherein said method comprises the steps of;

(1) under control of said CCD, configuring said IIC within said VIA;

(2) under control of said CCD, configuring said IIR within said VIA;

(3) under control of said CCD, electrically stimulating said IIC with said CDS;

(4) under control of said CCD, sensing said electrical state in said IIR with said ADC as a sensed current for a given row-column intersection within said VIA and converting said electrical state to digital data;

(5) under control of said CCD, storing said digital data in said TSM;

(6) under control of said CCD, determining if predetermined variations in said CDR, said IIC, and said IIR have been logged to said TSM, and if so, proceeding to step (8);

(7) under control of said CCD, reconfiguring said CDS, said IIC, and said IIR for a new VIA sensing variant and proceeding to step (3);

(8) under control of said CCD, interpolating said TSM values to determine focal points of activity within said VIA;

(9) under control of said CCD, converting said focal point activity information into a user interface input command sequence; and

(10) under control of said CCD, transmitting said user interface input command sequence to a computer system for action and proceeding to step (1).

38. The resistive touch sensor method of claim 37 wherein said drive electrodes reside on said top side of said second layer, said sense electrodes reside on said bottom side of said second layer, and vias interconnect said sense electrodes to conductive pads on said top side of said second layer.

39. The resistive touch sensor method of claim 37 wherein said sense electrodes reside on said top side of said second layer, said drive electrodes reside on said bottom side of said second layer, and vias interconnect said drive electrodes to conductive pads on said top side of said second layer.

40. The resistive touch sensor method of claim 37 wherein said sense electrodes comprise an upper surface and a lower surface, and said upper surface of said sense electrodes are planar.

41. The resistive touch sensor method of claim 37 wherein the row/column pitch of said drive electrodes and said sense electrodes is 1 mm.

42. The resistive touch sensor method of claim 37 wherein said drive electrodes and said sense electrodes form a rectangle pattern.

43. The resistive touch sensor method of claim 37 wherein said drive electrodes and said sense electrodes form an interdigitated finger pattern.

44. The resistive touch sensor method of claim 37 wherein said drive electrodes and said sense electrodes form a rectangle pattern with every other column flipped.

45. The resistive touch sensor method of claim 37 wherein said drive electrodes and said sense electrodes form an interdigitated finger pattern with every other column flipped.

46. The resistive touch sensor method of claim 37 wherein said drive electrodes and said sense electrodes form a diamond pattern.

47. The resistive touch sensor method of claim 37 wherein said drive electrodes and said sense electrodes form a non-rectangular force sensor array.

48. The resistive touch sensor method of claim 37 wherein said first layer comprises a thin layer having a high per-square resistance to bulk resistance ratio.

49. The resistive touch sensor method of claim 37 wherein said VIA comprises sensor elements having a resistance greater than that of the IIR impedances and the IIC impedances.

50. The resistive touch sensor method of claim 37 wherein said first layer comprises a force sensing layer that is segmented with segments aligning to force sensing elements within said VIA.

51. The resistive touch sensor method of claim 37 wherein said first layer comprises a polymer loaded with conductive particles.

52. The resistive touch sensor method of claim 37 wherein said first layer comprises a force sensing layer that is patterned.

53. The resistive touch sensor method of claim 37 wherein said first layer comprises a force sensing layer that is patterned with a random or pseudo-random pattern.

54. The resistive touch sensor method of claim 37 wherein said second layer comprises traces that further comprise a force sensing material.

55. The resistive touch sensor method of claim 37 wherein said first layer comprises a force sensing layer having material selected from a group consisting of:

conductive rubber;

conductive foam;

conductive plastic;

KAPTON®

loaded with conductive particles;

conductive ink;

a mixture of conductive particles with insulating particles; and

carbon particles mixed with a polymer.

56. The resistive touch sensor method of claim 37 wherein said second layer comprises conductive traces that are coated with gold plating.

57. The resistive touch sensor method of claim 37 wherein said second layer comprises conductive traces that are coated with an electroless nickel gold (ENIG) plating.

58. The resistive touch sensor method of claim 37 wherein said second layer comprises conductive traces that are coated with a screen printed carbon.

59. The resistive touch sensor method of claim 37 wherein said second layer comprises a rigid printed circuit board (PCB).

60. The resistive touch sensor method of claim 37 wherein said second layer comprises a rigid printed circuit board (PCB) comprising FR4 material.

61. The resistive touch sensor method of claim 37 wherein said second layer comprises a flexible printed circuit board (PCB).

62. The resistive touch sensor method of claim 37 wherein said second layer comprises a printed circuit board (PCB) formed using an additive printed electronics process.

63. The resistive touch sensor method of claim 37 wherein said second layer comprises mechanically drilled vias.

64. The resistive touch sensor method of claim 37 wherein said second layer comprises laser drilled vias.

65. The resistive touch sensor method of claim 37 wherein said second layer comprises filled vias.

66. The resistive touch sensor method of claim 37 wherein said second layer comprises vias formed by openings in a printed dielectric layer.

67. The resistive touch sensor method of claim 37 wherein said second layer comprises thin conductive bridges between said VIA columns.

68. The resistive touch sensor method of claim 37 wherein said second layer comprises thin conductive bridges between said VIA rows.

69. The resistive touch sensor method of claim 37 wherein said TSA comprises interpolation resistors further comprising discrete surface mount resistors.

70. The resistive touch sensor method of claim 37 wherein said TSA comprises interpolation resistors further comprising discrete surface mount resistors having an accuracy of 1% or better.

71. The resistive touch sensor method of claim 37 wherein said TSA comprises interpolation resistors further comprising laser trimmed resistors.

72. The resistive touch sensor method of claim 37 wherein said VIA is attached to a flexible display coated with a force sensing material (FSM) that forms said first layer.

73. A tangible non-transitory computer usable medium having computer-readable program code means comprising a resistive touch sensor method configured to operate on resistive touch sensor system comprising:

(a) touch sensor array (TSA);

(b) array column driver (ACD);

(c) column switching register (CSR);

(d) column driving source (CDS);

(e) array row sensor (ARS);

(f) row switching register (RSR);

(g) analog to digital converter (ADC); and

(h) computing control device (CCD);

wherein

said TSA comprises a variable impedance array (VIA) comprising VIA columns and VIA rows;

said VIA comprises a first layer having a top side and a bottom side;

said first layer comprises a force sensing material;

said VIA comprises a second layer having a top side and a bottom side;

said second layer comprises exposed coplanar drive electrodes;

said second layer further comprises coplanar sense electrodes;

said VIA is configured to electrically couple a plurality of interlinked impedance columns (IIC) within said TSA with a plurality of interlinked impedance rows (IIR) within said TSA;

said IIC further comprises a plurality of individual column impedance elements (ICIE) electrically connected in series between said drive electrodes;

said IIR further comprises a plurality of individual row impedance elements (IRIE) electrically connected in series between said sense electrodes;

said ACD is configured to select said IIC within said TSA based on said CSR;

said ACD is configured to electrically drive said selected IIC using said CDS;

said CDS is configured to power one or more of said drive electrodes while driving one or more of said drive electrodes to ground potential;

said ARS is configured to select said IIR within said TSA based on said RSR;

said ADC is configured to sense the electrical state of said selected IIR and convert said electrical state to a sensed digital value (SDV);

said ADC is configured to sense the voltage on one or more of said sense electrodes while simultaneously driving one or more of said sense electrodes to ground potential;

said electrical state is determined by the sum of current contributions of variable impedance elements within said VIA, where the current contribution of each element is determined by a voltage divider formed between the columns of said VIA, a current divider formed between the rows of said via, and the state of the impedance element, to produce a sensed current for a given row-column intersection with said VIA; and

said CCD is configured to sample said SDV from said ADC at a plurality of positions within said TSA to form a touch sensor matrix (TSM) data structure;

wherein said method comprises the steps of;

(1) under control of said CCD, configuring said IIC within said VIA;

(2) under control of said CCD, configuring said IIR within said VIA;

(3) under control of said CCD, electrically stimulating said IIC with said CDS;

(4) under control of said CCD, sensing said electrical state in said IIR with said ADC as a sensed current for a given row-column intersection within said VIA and converting said electrical state to digital data;

(5) under control of said CCD, storing said digital data in said TSM;

(6) under control of said CCD, determining if predetermined variations in said CDR, said IIC, and said IIR have been logged to said TSM, and if so, proceeding to step (8);

(7) under control of said CCD, reconfiguring said CDS, said IIC, and said IIR for a new VIA sensing variant and proceeding to step (3);

(8) under control of said CCD, interpolating said TSM values to determine focal points of activity within said VIA;

(9) under control of said CCD, converting said focal point activity information into a user interface input command sequence; and

(10) under control of said CCD, transmitting said user interface input command sequence to a computer system for action and proceeding to step (1).

74. The computer useable medium of claim 73 wherein said drive electrodes reside on said top side of said second layer, said sense electrodes reside on said bottom side of said second layer, and vias interconnect said sense electrodes to conductive pads on said top side of said second layer.

75. The computer useable medium of claim 73 wherein said sense electrodes reside on said top side of said second layer, said drive electrodes reside on said bottom side of said second layer, and vias interconnect said drive electrodes to conductive pads on said top side of said second layer.

76. The computer useable medium of claim 73 wherein said sense electrodes comprise an upper surface and a lower surface, and said upper surface of said sense electrodes are planar.

77. The computer useable medium of claim 73 wherein the row/column pitch of said drive electrodes and said sense electrodes is 1 mm.

78. The computer useable medium of claim 73 wherein said drive electrodes and said sense electrodes form a rectangle pattern.

79. The computer useable medium of claim 73 wherein said drive electrodes and said sense electrodes form an interdigitated finger pattern.

80. The computer useable medium of claim 73 wherein said drive electrodes and said sense electrodes form a rectangle pattern with every other column flipped.

81. The computer useable medium of claim 73 wherein said drive electrodes and said sense electrodes form an interdigitated finger pattern with every other column flipped.

82. The computer useable medium of claim 73 wherein said drive electrodes and said sense electrodes form a diamond pattern.

83. The computer useable medium of claim 73 wherein said drive electrodes and said sense electrodes form a non-rectangular force sensor array.

84. The computer useable medium of claim 73 wherein said first layer comprises a thin layer having a high per-square resistance to bulk resistance ratio.

85. The computer useable medium of claim 73 wherein said VIA comprises sensor elements having a resistance greater than that of the IIR impedances and the IIC impedances.

86. The computer useable medium of claim 73 wherein said first layer comprises a force sensing layer that is segmented with segments aligning to force sensing elements within said VIA.

87. The computer useable medium of claim 73 wherein said first layer comprises a polymer loaded with conductive particles.

88. The computer useable medium of claim 73 wherein said first layer comprises a force sensing layer that is patterned.

89. The computer useable medium of claim 73 wherein said first layer comprises a force sensing layer that is patterned with a random or pseudo-random pattern.

90. The computer useable medium of claim 73 wherein said second layer comprises traces that further comprise a force sensing material.

91. The computer useable medium of claim 73 wherein said first layer comprises a force sensing layer having material selected from a group consisting of:

conductive rubber;

conductive foam;

conductive plastic;

KAPTON®

loaded with conductive particles;

conductive ink;

a mixture of conductive particles with insulating particles; and

carbon particles mixed with a polymer.

92. The computer useable medium of claim 73 wherein said second layer comprises conductive traces that are coated with gold plating.

93. The computer useable medium of claim 73 wherein said second layer comprises conductive traces that are coated with an electroless nickel gold (ENIG) plating.

94. The computer useable medium of claim 73 wherein said second layer comprises conductive traces that are coated with a screen printed carbon.

95. The computer useable medium of claim 73 wherein said second layer comprises a rigid printed circuit board (PCB).

96. The computer useable medium of claim 73 wherein said second layer comprises a rigid printed circuit board (PCB) comprising FR4 material.

97. The computer useable medium of claim 73 wherein said second layer comprises a flexible printed circuit board (PCB).

98. The computer useable medium of claim 73 wherein said second layer comprises a printed circuit board (PCB) formed using an additive printed electronics process.

99. The computer useable medium of claim 73 wherein said second layer comprises mechanically drilled vias.

100. The computer useable medium of claim 73 wherein said second layer comprises laser drilled vias.

101. The computer useable medium of claim 73 wherein said second layer comprises filled vias.

102. The computer useable medium of claim 73 wherein said second layer comprises vias formed by openings in a printed dielectric layer.

103. The computer useable medium of claim 73 wherein said second layer comprises thin conductive bridges between said VIA columns.

104. The computer useable medium of claim 73 wherein said second layer comprises thin conductive bridges between said VIA rows.

105. The computer useable medium of claim 73 wherein said TSA comprises interpolation resistors further comprising discrete surface mount resistors.

106. The computer useable medium of claim 73 wherein said TSA comprises interpolation resistors further comprising discrete surface mount resistors having an accuracy of 1% or better.

107. The computer useable medium of claim 73 wherein said TSA comprises interpolation resistors further comprising laser trimmed resistors.

108. The computer useable medium of claim 73 wherein said VIA is attached to a flexible display coated with a force sensing material (FSM) that forms said first layer.