Method and apparatus for a touch sensitive system employing direct sequence spread spectrum (DSSS) technology

• US 7,084,860 B1
• Filed: 07/25/2002
• Issued: 08/01/2006
• Est. Priority Date: 06/08/2001
• Status: Expired due to Fees

• Current Assignee: Intertact Corporation
• Original Assignee: Intertact Corporation
• Inventors: Jaeger, Denny, Lohbihler, Andrew
• Primary Examiner(s): Tran, Henry N.
• Application Number:
  US10/207,716
• Time in Patent Office: 1,468 Days
• Field of Search: 345/173, 345/179, 178/18.01, 341/15, 341/22, 341/29
• US Class Current: 345/173
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/0433 in which the acoustic waves are either generated by a movable member and propagated within a surface layer or propagated within a surface layer and captured by a movable member
• CPC Class Codes: G06F 3/0436 in which generating transducers and detecting transducers are attached to a single acoustic waves transmission substrate

Abstract

A touch sensing apparatus for receiving input from one or more touch stimulating devices employs a direct sequence spread spectrum (DSSS) signaling arrangement to transmit signals from the touch stimulating devices for identification and location determination. Active devices are powered by an EM field and generate a touch stimulating signal that is spread spectrum encoded for identification, and signal pickups in a propagation layer receive the touch stimulation signals which are identified by the DSSS encoding and located using received signal strength (RSS) techniques. Semi-active devices are powered by an EM field and receive code instructions to generate specific spread spectrum signals and generate a touch-stimulating signal. Touch stimulating devices are either tethered or tether-free, and powered by batteries or EM fields.

Claims

1. A touch sensing system for identifying and locating one or more touch stimulating devices in a touch sensing area, including:

a signal propagating layer for conducting signals throughout said touch sensing area;

at least one of said touch stimulating devices including means for producing a touch excitation signal and coupling said signal to said propagating layer, said touch excitation signal comprising a spread spectrum signal;

each touch excitation signal including a unique code identifying the respective device;

signal pickup means connected to said propagating layer to receive at least one touch excitation signal from said one or more touch stimulating devices;

means for decoding said touch excitation signal to identify at least one of said touch stimulating devices;

means for determining the position of each of said one or more touch stimulating devices on said touch sensing area;

said at least one touch stimulating device including a user-operated switch, and said means for producing a touch excitation signal including means for encoding and transmitting the on-off state of said switch; and

,

said means for encoding and transmitting the on-off state of said switch including means for transmitting the complementary signal of said unique code of said at least one device.

2. The touch sensing system of claim 1, wherein said means for determining the position of each touch stimulating device includes received signal strength (RSS) means.

3. The touch sensing system of claim 1, wherein said spread spectrum signal comprises a direct sequence spread spectrum signal (DSSS).

4. The touch sensing system of claim 1, wherein said touch excitation signal is transmitted to said propagating layer at a frequency of at least 20 kHz.

5. A touch sensing system for identifying and locating one or more touch stimulating devices in a touch sensing area, including:

a signal propagating layer for conducting signals throughout said touch sensing area;

at least one of said touch stimulating devices including means for producing a touch excitation signal and coupling said signal to said propagating layer, said touch excitation signal comprising a spread spectrum signal;

each touch excitation signal including a unique code identifying the respective device;

signal pickup means connected to said propagating layer to receive at least one touch excitation signal from said one or more touch stimulating devices;

means for decoding said touch excitation signal to identify at least one of said touch stimulating devices; and

,

means for determining the position of each of said one or more touch stimulating devices on said touch sensing area;

wherein said means for decoding said touch excitation signal includes code reconstructor means for receiving pulse spikes of said touch excitation signal from said signal pickup means and restoring the signal structure of said touch excitation signal.

6. The touch sensing system of claim 5, wherein said code reconstructor means includes positive and negative channel means for receiving positive and negative pulse spikes respectively.

7. The touch sensing system of claim 6, wherein said code reconstructor means includes a charge reservoir, and said positive channel means includes means for detecting positive pulse spikes and increasing the voltage level of said charge reservoir in accordance with said positive pulse spikes.

8. The touch sensing system of claim 7, wherein said negative channel means includes means for detecting negative pulse spikes and decreasing the voltage level of said charge reservoir in accordance with said negative pulse spikes, whereby said voltage level of said charge reservoir represents said restored signal structure of said touch excitation signal.

9. A touch sensing system for identifying and locating one or more touch stimulating devices in a touch sensing area, including:

a signal propagating layer for conducting signals throughout said touch sensing area;

at least one of said touch stimulating devices including means for producing a touch excitation signal and coupling said signal to said propagating layer, said touch excitation signal comprising a spread spectrum signal;

each touch excitation signal including a unique code identifying the respective device;

signal pickup means connected to said propagating layer to receive at least one touch excitation signal from said one or more touch stimulating devices;

means for decoding said touch excitation signal to identify at least one of said touch stimulating devices; and

,

means for determining the position of each of said one or more touch stimulating devices on said touch sensing area;

wherein said at least one touch stimulating device includes a waveform generator and memory means connected to said waveform generator to store said unique code.

10. The touch sensing system of claim 9, wherein said unique code is stored as a plurality of CDMA chips in said memory means.

11. The touch sensing system of claim 10, further including clock means for fetching said CDMA chips in serial, stepwise fashion and transmitting said chips to said waveform generator.

12. The touch sensing system of claim 11, further including fixed delay chip means for applying a fixed time delay after said unique code is transmitted.

13. The touch sensing system of claim 12, further including means for transmitting a data signal from said means for decoding said touch excitation signal to said at least one device.

14. The touch sensing system of claim 13, wherein said data signal includes at least one bit, and said at least one device includes means for applying at least one additional delay chip to said waveform generator in response to receiving said at least one bit of said data signal.

15. A touch sensing system for identifying and locating one or more touch stimulating devices in a touch sensing area, including:

a signal propagating layer for conducting signals throughout said touch sensing area;

at least one of said touch stimulating devices including means for producing a touch excitation signal and coupling said signal to said propagating layer, said touch excitation signal comprising a spread spectrum signal;

each touch excitation signal including a unique code identifying the respective device;

signal pickup means connected to said propagating layer to receive at least one touch excitation signal from said one or more touch stimulating devices;

means for decoding said touch excitation signal to identify at least one of said touch stimulating devices; and

,

means for determining the position of each of said one or more touch stimulating devices on said touch sensing area;

said means for decoding said touch excitation signal including matched filter means for detecting said unique code of said at least one device;

wherein said means for decoding said touch excitation signal includes memory means for storing the unique codes of said one or more touch stimulating devices and providing said codes to said matched filter means.

16. The touch sensing system of claim 15, further including means for transmitting operating power to said at least one touch stimulating device.

17. The touch sensing system of claim 16, wherein said means for transmitting operating power includes a field transmitting coil disposed adjacent to said signal propagating layer, and a pickup coil disposed in said at least one touch stimulating device.

18. The touch sensing system of claim 17, wherein said transmitting coil and said pickup coil are tuned to substantially the same frequency.

19. The touch sensing system of claim 17, further including means for transmitting a data signal from said transmitting coil to said pickup coil.

20. The touch sensing system of claim 19, wherein said means for transmitting a data signal includes means for supplying a power signal to said transmitting coil, and means for modulating said power signal with said data signal.

21. The touch sensing system of claim 20, wherein said at least one touch stimulating device includes means for demodulating said power signal to detect said data signal.

22. The touch sensing system of claim 16, wherein said means for transmitting operating power includes a field transmitting coil for transmitting a power signal, and antenna means for receiving said power signal and generating sufficient power to drive said means for producing a touch excitation signal.

23. The touch sensing system of claim 22, wherein said antenna means includes a ferrite antenna and an antenna coil extending about said ferrite antenna.

24. The touch sensing system of claim 23, further including a capacitor connected to said antenna coil to form a resonant LC antenna tuned to the frequency of said power signal.

25. The touch sensing system of claim 24, wherein said capacitor is assembled to one end of said ferrite antenna.

26. The touch sensing system of claim 25, further including a hole extending through said ferrite antenna to receive a wire connecting said capacitor and said antenna coil.

27. The touch sensing system of claim 23, wherein said ferrite antenna comprises a toroidal component having an inner annular chamber, and said antenna coil is disposed within said inner annular chamber.

28. The touch sensing system of claim 27, wherein said inner annular chamber extends about an axial portion of said toroidal component, and said antenna coil is wound about said axial portion.

29. The touch sensing system of claim 28, further including a bore extending axially through said axial portion.

30. The touch sensing system of claim 27, wherein said inner annular chamber is open at one end to an end surface of said toroidal component.

31. The touch sensing system of claim 15, wherein said matched filter means include a parallel transposed-form FIR matched-filter.

32. The touch sensing system of claim 15, wherein said at least one touch stimulating device comprises a joystick controller.

33. The touch sensing system of claim 15, wherein said at least one touch stimulating device comprises a mouse controller.

34. The touch sensing system of claim 15, wherein said at least one touch stimulating device comprises a knob controller.

35. The touch sensing system of claim 15, wherein said at least one touch stimulating device comprises a fader controller.

36. The touch sensing system of claim 15, wherein a field transmitting coil is disposed adjacent to the periphery of said signal propagating layer, and further including a secondary transmitting coil disposed generally within said field transmitting coil.

37. The touch sensing system of claim 36, wherein said field transmitting coil and said secondary transmitting coil are arranged to generate EM fields that have generally aligned vertical components.

38. The touch sensing system of claim 37, wherein said secondary transmitting coil is disposed to span a central null zone in the vertical component of the EM field of said field transmitting coil.

39. The touch sensing system of claim 38, further including a ferromagnetic antenna disposed concentrically within said secondary transmitting coil.

40. The touch sensing system of claim 39, wherein said ferromagnetic antenna comprises a generally flat, sheet-like component, and said secondary transmitting coil is generally coplanar with said ferromagnetic antenna.

41. The touch sensing system of claim 36, wherein said field transmitting coil and said secondary transmitting coil are connected in parallel to an EM signal source.

42. The touch sensing system of claim 36, wherein said secondary transmitting coil is disposed adjacent to a back surface of said signal propagating layer.

43. The touch sensing system of claim 36, wherein said signal propagating layer is disposed superjacently to a flat panel display, and said secondary transmitting coil is disposed adjacent to a back surface of said flat panel display.

44. The touch sensing system of claim 36, further including a ferromagnetic antenna disposed concentrically within said secondary transmitting coil.

45. The touch sensing system of claim 44, wherein said ferromagnetic antenna comprises a generally flat, sheet-like component, and said secondary transmitting coil is generally coplanar with said ferromagnetic antenna.

46. A touch sensing system for identifying and locating one or more touch stimulating devices in a touch sensing area, including:

a signal propagating layer for conducting signals throughout said touch sensing area;

at least one of said touch stimulating devices including means for producing a touch excitation signal and coupling said signal to said propagating layer, said touch excitation signal comprising a spread spectrum signal;

each touch excitation signal including a unique code identifying the respective touch stimulating device;

signal pickup means connected to said propagating layer to receive at least one touch excitation signal from said one or more touch stimulating devices;

means for decoding said touch excitation signal to identify at least one of said touch stimulating devices; and

,

means for determining the position of each of said one or more touch stimulating devices on said touch sensing area;

said means for decoding said touch excitation signal including matched filter means for detecting said unique code of said at least one device;

further including signal normalization means for receiving the output of said matched filter means and normalizing the amplitude of said output.

47. The touch sensing system of claim 46, wherein said means for determining the position includes received signal strength means for receiving said output of said normalization means and calculating the position of said at least one device on said propagating layer.

48. A touch sensing system for identifying and locating one or more touch stimulating devices in a touch sensing area, including:

a signal propagating layer for conducting signals throughout said touch sensing area;

at least one of said touch stimulating devices including means for producing a touch excitation signal and coupling said signal to said propagating layer;

means for determining the position of each of said one or more touch stimulating devices on said screen assembly;

means for transmitting operating power to said at least one touch stimulating device, including a field transmitting coil disposed adjacent to said signal propagating layer and a secondary transmitting coil disposed at a back surface of said signal propagating layer, and a pickup coil disposed in said at least one touch stimulating device, said field coil and secondary coil transmitting a combined EM field at a resonant frequency to said pickup coil.

49. The touch sensing system of claim 48, wherein said field transmitting coil is disposed adjacent to the periphery of said signal propagating layer, and said secondary transmitting coil is disposed generally within said field transmitting coil.

50. The touch sensing system of claim 49, wherein said field transmitting coil and said secondary transmitting coil are arranged to generate EM fields that have generally aligned vertical components.

51. The touch sensing system of claim 49, wherein said field transmitting coil and said secondary transmitting coil are connected in parallel to an EM signal source.

52. The touch sensing system of claim 49, wherein said secondary transmitting coil is disposed adjacent to a back surface of said signal propagating layer.

53. The touch sensing system of claim 49, wherein said signal propagating layer is disposed superjacently to a flat panel display, and said secondary transmitting coil is disposed adjacent to a back surface of said flat panel display.

54. The touch sensing system of claim 49, wherein said secondary transmitting coil is disposed to span a central null zone in the vertical component of the EM field of said field transmitting coil.

55. The touch sensing system of claim 49, further including a ferromagnetic antenna disposed concentrically within said secondary transmitting coil.

56. The touch sensing system of claim 55, wherein said ferromagnetic antenna comprises a generally flat, sheet-like component, and said secondary transmitting coil is generally coplanar with said ferromagnetic antenna.

57. A touch sensing system for identifying and locating one or more touch stimulating devices in a touch sensing area, including:

a signal propagating layer for conducting signals throughout said touch sensing area;

at least one of said touch stimulating devices including means for producing a touch excitation signal and coupling said signal to said propagating layer;

each touch excitation signal including a unique code identifying the respective device;

signal pickup means connected to said propagating layer to receive at least one touch excitation signal from said one or more touch stimulating devices;

means for decoding said touch excitation signal to identify at least one of said touch stimulating devices;

means for determining the position of each of said one or more touch stimulating devices on said screen assembly;

means for transmitting operating power to said at least one touch stimulating device, including a field transmitting coil for transmitting a power signal, and antenna means for receiving said power signal and generating sufficient power to drive said means for producing a touch excitation signal;

said antenna means including a ferrite antenna and an antenna coil extending about said ferrite antenna.

58. The touch sensing system of claim 57, further including a capacitor connected to said antenna coil to form a resonant LC antenna tuned to the frequency of said power signal.