Two-dimensional sensor arrays

• US 9,442,614 B2
• Filed: 08/20/2014
• Issued: 09/13/2016
• Est. Priority Date: 05/15/2014
• Status: Active Grant

• Current Assignee: BeBop Sensors, Inc.
• Original Assignee: BeBop Sensors, Inc.
• Inventors: McMillen, Keith A.
• Primary Examiner(s): MERCEDES, DISMERY E
• Application Number:
  US14/464,551
• Publication Number:
  US 20150331523A1
• Time in Patent Office: 755 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: A43B 3/34 with electrical or electronic arrangements
• CPC Class Codes: A61B 2090/064 for measuring force, pressure or mechanical tension
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 2562/046 in a matrix array
• CPC Class Codes: A61B 5/6804 Garments; Clothes
• CPC Class Codes: A61B 5/6807 Footwear
• CPC Class Codes: A61B 5/6843 Monitoring or controlling sensor contact pressure
• CPC Class Codes: G01L 1/18 using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material
• CPC Class Codes: G01L 1/205 using distributed sensing elements
• CPC Class Codes: G01L 5/0019 by using strain gages, piezoelectric, piezo-resistive or other ohmic-resistance based sensors
• CPC Class Codes: G01L 9/0052 of piezoresistive elements circuits therefor G01L9/06
• CPC Class Codes: G01L 9/06 of piezo-resistive devices
• CPC Class Codes: G06F 1/16 Constructional details or arrangements
• CPC Class Codes: G06F 2203/04102 Flexible digitiser, i.e. constructional details for allowing the whole digitising part of a device to be flexed or rolled like a sheet of paper
• 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 2203/04112 Electrode mesh in capacitive digitiser: electrode for touch sensing is formed of a mesh of very fine, normally metallic, interconnected lines that are almost invisible to see. This provides a quite large but transparent electrode surface, without need for ITO or similar transparent conductive material
• CPC Class Codes: G06F 3/04146 using pressure sensitive conductive elements delivering a boolean signal and located between crossing sensing lines, e.g. located between X and Y sensing line layers
• 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 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/045 : using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Abstract

Two-dimensional sensor arrays incorporating piezoresistive materials are described.

Claims

1. A sensor array, comprising:

a piezoresistive substrate;

a first array of conductive traces formed on the piezoresistive substrate and aligned with a first dimension of the sensor array, the conductive traces of the first array being characterized by a first conductivity;

a second array of conductive traces formed on the piezoresistive substrate and aligned with a second dimension of the sensor array, the conductive traces of the second array being characterized by a second conductivity higher than the first conductivity; and

circuitry configured to apply drive signals to the first array of conductive traces, to receive detection signals from the second array of conductive traces, and to determine one or more locations of one or more corresponding touch events on a surface of the sensor array using the drive and detection signals, wherein the circuitry is further configured to drive one end of a first conductive trace of the first array with a first signal, and to drive an opposing end of the first conductive trace with a second signal, the circuitry being further configured to receive a mixed signal from a second conductive trace of the second array, the mixed signal including contributions from the first and second signals via the piezoresistive substrate, the circuitry being further configured to determine a first location of a first touch event along the first conductive trace with reference to a first value representing the contributions of the first and second signals to the mixed signal.

2. The sensor array of claim 1, wherein the piezoresistive substrate comprises a flexible piezoresistive material.

3. The sensor array of claim 1, wherein the first and second arrays of conductive traces are formed on only one side of the piezoresistive substrate, or on both sides of the piezoresistive substrate.

4. The sensor array of claim 1, wherein the conductive traces of the first array are substantially parallel to each other and oriented along the first dimension, and wherein the conductive traces of the second array are substantially parallel to each other and oriented along the second dimension, the first and second dimensions being substantially perpendicular to each other.

5. The sensor array of claim 1, wherein the circuitry is further configured to determine one or more additional locations of one or more additional touch events along any of the conductive traces of the first array that are substantially simultaneous with the first touch event with reference to one or more additional values representing one or more additional mixed signals received from one or more of the conductive traces of the second array.

6. The sensor array of claim 1, wherein the circuitry is further configured to determine the first location of the first touch event as being along the first conductive trace and between adjacent conductive traces of the second array.

7. The sensor array of claim 6, wherein the circuitry is configured to determine the first location of the first touch event with reference to an additional value representing an additional mixed signal received from an additional conductive trace of the second array.

8. The sensor array of claim 1, wherein the circuitry is further configured to determine a second location of second touch event along the first conductive trace that is substantially simultaneous with the first touch event with reference to the first value and an additional value representing an additional mixed signal received from an additional conductive trace of the second array.

9. The sensor array of claim 1, wherein the circuitry is further configured to drive one end of a third conductive trace of the first array with the first signal, and to drive an opposing end of the third conductive trace with a third signal, wherein the mixed signal also includes additional contributions from the first signal and the third signal corresponding to a second touch event near the third conductive trace that is substantially simultaneous with the first touch event, and wherein the circuitry is further configured to generate the first value with reference to the additional contributions from the first and third signals corresponding to the second touch event.

10. The sensor array of claim 1, wherein the circuitry is configured to resolve the first location of the first touch event to one of a plurality of discrete locations associated with the first conductive trace on the surface of the sensor array.

11. The sensor array of claim 1, wherein the circuitry is further configured to determine a force value for each touch event representing a magnitude of a force for the corresponding touch event.

12. The sensor array of claim 11, wherein the circuitry is configured to determine the force value for each touch event with reference to an amplitude of a corresponding one of the detection signals.

13. The sensor array of claim 1, wherein each of the conductive traces of the first array coincides with each of the conductive traces of the second array, and wherein the circuitry is further configured to generate a data set for the sensor array with reference to the detection signals, the data set including a data value for each coincidence of one of the conductive traces of the first array with one of the conductive traces of the second array, the circuitry being configured to determine the one or more locations of the one or more corresponding touch events with reference to the data set.

14. The sensor array of claim 13, wherein the circuitry is further configured to determine a first location of a first touch event near a first coincidence of a first conductive trace of the first array and a second conductive trace of the second array by comparing the data value corresponding to the first coincidence to a threshold.

15. The sensor array of claim 14, wherein the threshold is determined with reference to an average of the data values.

16. The sensor array of claim 13, wherein the circuitry is configured to repeat generation of the data set resulting in a plurality of data sets, each data set representing a state of the sensor array for a corresponding period of time, the circuitry being configured to determine the one or more locations of the one or more corresponding touch events with reference to the plurality of data sets.

17. The sensor array of claim 16, wherein the circuitry is configured to determine the one or more locations of the one or more corresponding touch events with reference to the plurality of data sets by comparing corresponding data values in successive ones of the data sets.

18. The sensor array of claim 13, wherein the circuitry is configured to generate first and second data values for each coincidence of one of the conductive traces of the first array with one of the conductive traces of the second array, the first data value representing a location of any nearby touch event along the corresponding conductive trace of the first array, and the second data value representing a force associated with the nearby touch event.

19. The sensor array of claim 1, wherein the circuitry is configured to determine a plurality of locations of a plurality of substantially simultaneous touch events on the surface of the sensor array using the drive and detection signals.

20. The sensor array of claim 1, wherein the circuitry is configured to resolve detected touch events to a plurality of discrete locations on the surface of the sensor array.

21. The sensor array of claim 20, further comprising a plurality of force focusing elements, each force focusing element being aligned with one of the discrete locations.

22. The sensor array of claim 21, wherein the force focusing elements are part of the piezoresistive substrate.

23. The sensor array of claim 21, further comprising an additional substrate adjacent to a combination of the first and second arrays of conductive traces and the piezoresistive substrate, the additional substrate having the force focusing elements formed thereon.

24. The sensor array of claim 23, wherein the force focusing elements comprises convex features on the additional substrate.

25. The sensor array of claim 23, wherein the additional substrate is part of an environmental protection enclosure for the combination of the first and second arrays of conductive traces and the piezoresistive substrate.

26. The sensor array of claim 21, wherein one or both of a form factor of the force focusing elements and a flexibility of the force focusing elements is controlled to achieve a corresponding dynamic range of the sensor array.

27. The sensor array of claim 1, further comprising a first additional substrate adjacent to a combination of the first and second arrays of conductive traces and the piezoresistive substrate, the first additional substrate having a plurality of structural elements extending therefrom at least partially through the piezoresistive substrate in spaces between the conductive traces, the sensor array further comprising a second additional substrate adjacent to the combination of the first and second arrays of conductive traces and the piezoresistive substrate on an opposite side of the combination from the first additional substrate.

28. The sensor array of claim 27, wherein the structural elements extend all of the way through the piezoresistive substrate and contact the second additional substrate without force exerted on the surface of the sensor array.

29. The sensor array of claim 27, wherein the structural elements extend only part of the way through the piezoresistive substrate.

30. The sensor array of claim 27, wherein the first and second additional substrates are part of an environmental protection enclosure for the combination of the first and second arrays of conductive traces and the piezoresistive substrate.

31. The sensor array of claim 1, wherein the piezoresistive substrate includes a plurality of apertures, each of the apertures being aligned with a space between the conductive traces of the first and second arrays.

32. The sensor array of claim 31, further comprising an additional substrate adjacent to a combination of the first and second arrays of conductive traces and the piezoresistive substrate, the additional substrate having a plurality of structural elements extending therefrom at least partially through the apertures of the piezoresistive substrate.

33. The sensor array of claim 32, wherein the structural elements have a form factor corresponding to a shape of the apertures.

34. The sensor array of claim 1, wherein the conductive traces of the first array are resistive traces, and wherein the circuitry is configured to energize each of the conductive traces of the first array by simultaneously driving opposing ends of the conductive trace with first and second signals, respectively, using a plurality of signal busses, each signal buss being connected to a plurality of the conductive traces of the first array, the opposing ends of each conductive trace of the first array being connected to a unique pair of the busses.

35. The sensor array of claim 34, wherein the conductive traces of the second array are characterized by substantially zero resistance, and wherein at least some of the locations at which the circuitry is configured to determine touch events are along corresponding ones of the conductive traces of the first array and between respective pairs of the conductive traces of the second array.

36. The sensor array of claim 1, wherein the circuitry is configured to resolve detected touch events to a plurality of discrete locations on the surface of the sensor array, the plurality of discrete locations forming an array of Y discrete locations along the first dimension by X discrete locations along the second dimension, the first array of conductive traces including X conductive traces, and the second array of conductive traces including fewer than Y conductive traces, where X and Y are integers greater than zero.

37. The sensor array of claim 1, wherein the circuitry is configured to resolve detected touch events to a plurality of discrete locations on the surface of the sensor array, the plurality of discrete locations forming an array of Y discrete locations along the first dimension by X discrete locations along the second dimension, the first array of conductive traces including X conductive traces, where X and Y are integers greater than zero, the sensor array further comprising a plurality of busses by which the circuitry applies the drive signals to the first array of conductive traces, the plurality of busses including fewer than X busses.

38. The sensor array of claim 1, wherein each of the conductive traces of the first array coincides with each of the conductive traces of the second array, the sensor array further comprising a trace pattern at each coincidence of one of the conductive traces of the first array with one of the conductive traces of the second array, each trace pattern including a first trace extending from the corresponding conductive trace of the first array and a second trace extending from the corresponding conductive trace of the second array, the first and second traces having complementary shapes.

39. The sensor array of claim 38, wherein the complementary shapes of the first and second traces of each trace pattern comprise a clover shape and a cruciform shape.

40. The sensor array of claim 38, wherein one or both of the shapes of the first and second traces and the distance between the first and second traces is controlled to achieve a corresponding dynamic range of the sensor array.

41. A sensor array, comprising:

a first array of conductive traces aligned with a first dimension of the sensor array, the conductive traces of the first array characterized by a first conductivity;

a second array of conductive traces aligned with a second dimension of the sensor array, the conductive traces of the second array characterized by a second conductivity higher than the first conductivity;

piezoresistive material configured to provide electrical connectivity between the conductive traces of the first and second arrays; and

circuitry configured to apply drive signals to the first array of conductive traces, to receive detection signals from the second array of conductive traces, and to determine one or more locations of one or more corresponding touch events on a surface of the sensor array using the drive and detection signals, the circuitry being further configured to drive one end of a first conductive trace of the first array with a first signal, and to drive an opposing end of the first conductive trace with a second signal, the circuitry being further configured to receive a mixed signal from a second conductive trace of the second array, the mixed signal including contributions from the first and second signals via the piezoresistive material, the circuitry being further configured to determine a first location of a first touch event along the first conductive trace with reference to a first value representing the contributions of the first and second signals to the mixed signal.

42. The sensor array of claim 41, wherein the circuitry is further configured to determine one or more additional locations of one or more additional touch events along any of the conductive traces of the first array that are substantially simultaneous with the first touch event with reference to one or more additional values representing one or more additional mixed signals received from one or more of the conductive traces of the second array.

43. The sensor array of claim 41, wherein the circuitry is further configured to determine the first location of the first touch event as being along the first conductive trace and between adjacent conductive traces of the second array.

44. The sensor array of claim 43, wherein the circuitry is configured to determine the first location of the first touch event with reference to an additional value representing an additional mixed signal received from an additional conductive trace of the second array.

45. The sensor array of claim 41, wherein the circuitry is further configured to determine a second location of second touch event along the first conductive trace that is substantially simultaneous with the first touch event with reference to the first value and an additional value representing an additional mixed signal received from an additional conductive trace of the second array.

46. The sensor array of claim 41, wherein the circuitry is further configured to drive one end of a third conductive trace of the first array with the first signal, and to drive an opposing end of the third conductive trace with a third signal, wherein the mixed signal also includes additional contributions from the first signal and the third signal corresponding to a second touch event near the third conductive trace that is substantially simultaneous with the first touch event, and wherein the circuitry is further configured to generate the first value with reference to the additional contributions from the first and third signals corresponding to the second touch event.

47. The sensor array of claim 41, wherein the circuitry is configured to resolve the first location of the first touch event to one of a plurality of discrete locations associated with the first conductive trace on the surface of the sensor array.

48. The sensor array of claim 41, wherein the conductive traces of the first array are resistive traces, and wherein the circuitry is configured to energize each of the conductive traces of the first array by simultaneously driving opposing ends of the conductive trace with first and second signals, respectively, using a plurality of signal busses, each signal buss being connected to a plurality of the conductive traces of the first array, the opposing ends of each conductive trace of the first array being connected to a unique pair of the busses.

49. The sensor array of claim 48, wherein the conductive traces of the second array are characterized by substantially zero resistance, and wherein at least some of the locations at which the circuitry is configured to determine touch events are along corresponding ones of the conductive traces of the first array and between respective pairs of the conductive traces of the second array.

50. The sensor array of claim 41, wherein the circuitry is configured to resolve detected touch events to a plurality of discrete locations on the surface of the sensor array, the plurality of discrete locations forming an array of Y discrete locations along the first dimension by X discrete locations along the second dimension, the first array of conductive traces including X conductive traces, and the second array of conductive traces including fewer than Y conductive traces, where X and Y are integers greater than zero.

51. The sensor array of claim 41, wherein circuitry is configured to resolve detected touch events to a plurality of discrete locations on the surface of the sensor array, the plurality of discrete locations forming an array of Y discrete locations along the first dimension by X discrete locations along the second dimension, the first array of conductive traces including X conductive traces, where X and Y are integers greater than zero, the sensor array further comprising a plurality of busses by which the circuitry applies the drive signals to the first array of conductive traces, the plurality of busses including fewer than X busses.

52. The sensor array of claim 41, wherein the piezoresistive material comprises a flexible piezoresistive substrate.

53. The sensor array of claim 52, wherein the first and second arrays of conductive traces are formed on the flexible piezoresistive substrate.

54. The sensor array of claim 53, wherein the first and second arrays of conductive traces are formed on only one side of the flexible piezoresistive substrate, or on both sides of the flexible piezoresistive substrate.

55. The sensor array of claim 41, wherein one or both of the first and second arrays of conductive traces are formed on one or more additional substrates adjacent to the flexible piezoresistive substrate.