System and method for optimizing personal area network (PAN) electrostatic communication

• US 6,542,717 B1
• Filed: 01/20/1999
• Issued: 04/01/2003
• Est. Priority Date: 01/20/1999
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Vogt, Florian, Allen, Richard Clement, Zimmerman, Thomas Guthrie, Lu, David Jun
• Primary Examiner(s): Bost, Dwayne
• Assistant Examiner(s): WEST, LEWIS G
• Application Number:
  US09/234,229
• Time in Patent Office: 1,532 Days
• Field of Search: 455/100, 455/41, 455/67.1, 455/67.4, 455/500, 455/272, 455/344, 340/573.1, 340/573.2, 340/573.3, 340/573.4, 340/407.1, 340/407.2, 343/718
• US Class Current: 455/41.1
• CPC Class Codes: G06K 7/10336 the antenna being of the near field type, inductive coil
• CPC Class Codes: H04B 5/48 Transceivers

Abstract

Systems and methods for optimizing performance of personal area network (PAN) systems that use electric fields as communication media between PAN transmitters carried by people and PAN receivers mounted on computers to which selective access is sought to be established. Multiple PAN receiver antennae are mounted on a keyboard, such that if a person with a PAN transmitter rests her arms on or near the keyboard, sufficient signal from the transmitter is sensed by one or more of the receiver antennae even though some of the signal is shunted away from the receivers through the arms. Also, a driven shield insulates a PAN receiver from nearby metal objects, e.g., a desk on which the PAN receiver is supported. Moreover, a multiple-electrode PAN transmitter reduces the deleterious effects on the signal from the PAN transmitter that can otherwise be caused by, e.g., loose metal coins that are present in a pocket in which the transmitter is carried. Further, differential receive electrodes prevents undesirable coupling of a PAN transmitted signal to a computer'"'"'s receiver through a person who has positioned herself between the receiver and the person carrying the PAN transmitter to, for example, gain unauthorized access to the computer.

Claims

1. A PAN communication system that communicates information via an electric field from a PAN transmitter to a PAN receiver, the receiver including at least one receive electrode disposed above a support, comprising:

a driven shield disposed on the support between the receive electrode and the support; and

an insulator layer sandwiched between the receive electrode and the driven shield, whereby

the receive electrode is substantially shielded from the support.

2. The communication system of claim 1, further comprising an amplifier electrically connected to the driven shield and to the receiver, the driven shield being insulated from ground.

3. The communication system of claim 2, wherein the amplifier is a unity gain amplifier, such that the amplifier establishes a buffer.

4. The communication system of claim 1, further comprising:

a computer associated with the receiver; and

plural PAN receiver antennae associated with the receiver such that communication can be established between the PAN transmitter and the computer, the receive electrode establishing one of the receiver antennae.

5. The communication system of claim 4, wherein communication between the transmitter and computer is established using an electric field.

6. The communication system of claim 5, further comprising a data input device communicating with the computer, the receiver antennae being mounted on the data input device.

7. The communication system of claim 6, wherein the data input device is a keyboard.

8. The communication system of claim 5, wherein the system includes at least three receiver antennae.

9. The communication system of claim 7, wherein the keyboard defines left and right sides relative to a user of the keyboard, and at least one of the receiver antennae extends substantially from the left side to the right side.

10. The communication system of claim 4, wherein the receiver is associated with a signal, and the system further comprises:

a computer program storage device readable by the computer; and

a program means on the program storage device and including instructions executable by the computer for performing method steps for establishing a combination of the receiver antennae, the method steps comprising;

decoupling a first one of the antennae from the receiver;

determining whether the signal exhibits a predetermined change as a result of the decoupling of the first antenna; and

recoupling the first antenna to the receiver if the signal does not exhibit the predetermined change.

11. The communication system of claim 10, wherein the method steps undertaken by the instructions include serially decoupling each antenna and determining whether the signal exhibits a predetermined change as a result of the decoupling of each antenna.

12. In a PAN communication system, a PAN transmitter including plural transmitter electrodes, wherein the electrodes include at least one driven electrode juxtaposed with at least one reference electrode, the driven electrode being insulated from the reference electrode.

13. The transmitter of claim 12, comprising at least first and second driven electrodes, each driven electrode being energized by a respective buffer circuit.

14. The transmitter of claim 12, further comprising at least one signal generator electrically connected to each buffer circuit.

15. A PAN communication system comprising:

at least one PAN receiver including first receive electrode; and

at least one second receive electrode positioned adjacent the first receive electrode, said first and second receive electrodes having substantially the same electric potential when a first person not bearing the PAN transmitter interacts with said first and second receive electrodes to prevent communication from the PAN transmitter to the receiver via the first person, said first and second receive electrodes having a substantially different electric potential when a second person bearing the PAN transmitter interacts with said first and second receive electrodes to permit communication from the PAN transmitter to the receiver.

16. The PAN communication system of claim 15, further comprising a guard electrode juxtaposed with and insulated from one or more receive electrodes, the guard electrode being insulated from ground.

17. The PAN communication system of claim 16, further comprising a guard driving follower amplifier electrically connected to a receive electrode and the guard electrode.

18. The PAN communication system of claim 15, further comprising a differential receive amplifier electrically connected to said first and second electrodes.

19. A PAN communication system, comprising:

at least one PAN receiver including at least one receive electrode;

at least one portable PAN transmitter; and

at least a pair of differential receive electrodes for interaction by a person, the receive electrodes having substantially the same electric potential when a first person not bearing the PAN transmitter interacts with the receive electrodes to prevent communication from the PAN transmitter to the receiver via the first person, the receive electrodes having a substantially different electric potential when a second person bearing the PAN transmitter interacts with the receive electrodes to permit communication from the PAN transmitter to the receiver.

20. The PAN communication system of claim 19, further comprising a guard electrode juxtaposed with and insulated from at least one receive electrode, the guard electrode being insulated from ground.

21. The PAN communication system of claim 20, further comprising a guard driving follower amplifier electrically connected to the guard electrode and the receive electrode.

22. The PAN communication system of claim 19, further comprising a differential receive amplifier electrically connected to the receive electrodes.

23. The communication system of claim 19, wherein the PAN transmitter includes plural transmitter electrodes.

24. The communication system of claim 23, wherein the transmitter electrodes include a plurality of driven electrodes juxtaposed with at least one reference electrode, the driven electrodes being insulated from the reference electrode.

25. The communication system of claim 24, wherein the transmitter comprises at least first and second driven electrodes, each driven electrode being energized by a respective buffer circuit.

26. The communication system of claim 25, further comprising at least one signal generator electrically connected to each buffer circuit.

27. An electrostatic communication system for communicating data between a portable transmitter and a computer system nearby the transmitter using an electric field affected by a person bearing the transmitter, comprising:

a receiver including plural receiver antennae associated with the computer system such that at least some electric field lines from the person are not shunted away from at least one of the receiver antennae when the person moves an arm toward the computer system, the receiver being associated with a signal;

logic means for decoupling a first one of the antennae from the receiver;

logic means for determining whether the signal exhibits a predetermined change as a result of the decoupling of the first antenna; and

logic means for recoupling the first antenna to the receiver if the signal does not exhibit the predetermined change.

28. The communication system of claim 27, wherein the computer system includes a computer and a data entry device for inputting data into the computer, the receiver antennae being mounted on the data entry device.

29. The communication system of claim 28, wherein the communication system includes at least three receiver antennae.

30. The communication system of claim 29, wherein the keyboard defines left and right sides relative to a user of the keyboard, and at least one of the receiver antennae extends substantially from the left side to the right side.

31. The communication system of claim 27, further comprising logic means for serially decoupling each antenna and determining whether the signal exhibits a predetermined change as a result of the decoupling of each antenna.

32. The communication system of claim 27, wherein the receiver antennae are receive electrodes disposed above a support, and the system further comprises:

a driven shield disposed on the support between at least a first one of the receive electrodes and the support; and

an insulator sandwiched between the first one of the receive electrodes and the driven shield, whereby

the first one of the receive electrodes is substantially shielded from the support.

33. A near field communication system, comprising:

a receive electrode disposed above a surface; and

a driven shield disposed between the receive electrode and the surface to shield the receive electrode from the surface.

34. The communication system of claim 33, further comprising:

a receiver electrically connected to the receive electrode; and

a drive amplifier electrically connected to the receiver and the driven shield, the driven shield being insulated from the receive electrode.

35. A communication system, comprising:

an electric field transmitter including at least first and second driven electrodes both facing at least one reference electrode.

36. The communication system of claim 35, wherein each driven electrode is energized by a respective buffer circuit.

37. The communication system of claim 36, further comprising at least one signal generator electrically connected to each buffer circuit.

38. A communication system, comprising:

a computer;

an electric field receiver associated with the computer;

at least one receive electrode electrically connected to the receiver;

a portable electric field transmitter bearable by a first person for communicating with the computer via the receiver; and

means for preventing communication between the transmitter and receiver when a second person not bearing an electric field transmitter is interposed between the transmitter and the receiver.

39. The system of claim 38, wherein the means for preventing includes at least a pair of receive electrodes for interaction by a person, said receive electrodes having substantially the same electric potential when a second person not bearing the PAN transmitter interacts with said receive electrodes to prevent communication from the PAN transmitter to the receiver via the second person, said receive electrodes having a substantially different electric potential when a first person bearing the PAN transmitter interacts with said receive electrodes to permit communication from the PAN transmitter to the receiver.

40. The communication system of claim 39, further comprising a guard electrode juxtaposed with and insulated from at least one receive electrode, the guard electrode being insulated from ground.

41. The communication system of claim 40, further comprising a guard driving follower amplifier electrically connected to the guard electrode and said receive electrode.

42. The communication system of claim 41, further comprising a differential receive amplifier electrically connected to said pair of receive electrodes.

43. The communication system of claim 38, so wherein the receiver is associated with a signal, and wherein means for preventing includes a detector for detecting a predetermined characteristic in the signal when a first person bearing the transmitter moves a limb toward the receive electrode.

44. The communication system of claim 43, wherein the predetermined characteristic is at least one of:

an amplitude minimum, and a change of phase.

45. A PAN communication system, comprising:

at least one PAN receiver; and

at least one portable PAN transmitter comprising at least first and second driven electrodes, each driven electrode being energized by a respective buffer circuit.

46. A personal area network (PAN) communication system, comprising:

a PAN transmitter;

a computer;

more than one PAN receiver antenna on a keyboard associated with the computer, the keyboard defining left and right sides relative to a user of the keyboard, at least one of the receiver antennae being elongated and extending substantially across the keyboard from substantially the left side to substantially the right side such that communication can be established between the PAN transmitter and the computer.

47. The communication system of claim 46, wherein the system includes at least three receiver antennae.

48. A personal area network (PAN) communication system, comprising:

a PAN transmitter;

a computer;

more than one PAN receiver antenna associated with the computer such that communication can be established between the PAN transmitter and the computer, wherein the receiver antennae are associated with a receiver, the receiver being associated with a signal;

logic means for decoupling a first one of the antennae from the receiver;

logic means for determining whether the signal exhibits a predetermined change as a result of the decoupling of the first antenna; and

logic means for recoupling the first antenna to the receiver if the signal does not exhibit the predetermined change.

49. The communication system of claim 48, further comprising logic means for serially decoupling each antenna and determining whether the signal exhibits a predetermined change as a result of the decoupling of each antenna.

50. A personal area network (PAN) communication system, comprising:

a PAN transmitter;

a computer;

more than one PAN receiver antenna associated with the computer such that communication can be established between the PAN transmitter and the computer, wherein the receiver antennae are receive electrodes disposed above a support and associated with at least one receiver;

a driven shield disposed on the support between at least a first one of the receive electrodes and the support, the driven shield being insulated from ground; and

an insulator layer sandwiched between the first one of the receive electrodes and the driven shield, whereby

the first one of the receive electrodes is substantially shielded from the support.

51. The communication system of claim 50, further comprising a unity gain amplifier electrically connected to the driven shield and to the receiver.