Multi-user touch surface

• US 6,498,590 B1
• Filed: 05/24/2001
• Issued: 12/24/2002
• Est. Priority Date: 05/24/2001
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Inventors: Dietz, Paul H., Leigh, Darren L.
• Primary Examiner(s): Ho, Tan
• Application Number:
  US09/864,833
• Publication Number:
  US 20020185981A1
• Time in Patent Office: 579 Days
• Field of Search: 343/700.MS, 343/718, 343/812, 343/841, 343/853, 343/893, 370/401, 370/465, 370/466, 370/480, 370/481, 323/904, 340/286.1, 340/286.2
• US Class Current: 343/893
• CPC Class Codes: G06F 3/038 Control and interface arrangements therefor, e.g. drivers or device-embedded control circuitry
• 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: Y10S 323/904 Touch systems

Abstract

A multi-user touch system includes a surface on which are a pattern of mounted antennas. A transmitter transmits uniquely identifiable signals to each antenna. Receivers are capacitively coupled to different users, the receivers are configured to receive the uniquely identifiable signals. A processor then associates a specific antenna with a particular users when multiple users simultaneously touch any of the antennas.

Claims

1. A multi-user touch system, comprising:

a touch sensitive surface including a plurality of antennas mounted thereon;

a transmitter configured to transmit uniquely identifiable signals to each antenna;

plurality of receivers, each receiver capacitively coupled to a different user, the receivers configured to receive the uniquely identifiable signals;

means for associating a specific antenna with a particular user when multiple users simultaneously touch any of the plurality of antennas.

2. The system of claim 1 wherein the touch sensitive surface further comprises:

a plurality of conductive pads arranged in rows and columns.

3. The system of claim 2 wherein the plurality of conductive pads are arranged on a laminated substrate.

4. The system of claim 2 wherein the means for associating further comprises:

means for driving the uniquely identifiable signals to each antenna in turn; and

means for measuring times when the transmitted signals are present at the receivers to differentiate the antennas.

5. The system of claim 1 wherein each receiver further comprises:

an amplifier connected to a synchronous demodulator;

an analog-to-digital converter coupled an output of the synchronous demodulator.

6. The system of claim 1 wherein the transmitter and each receiver are connected to a processor for associating the specific antenna with each particular user.

7. The system of claim 1 wherein the surface is disposed on a table top.

8. The system of claim 1 wherein the surface is mounted on a wall.

9. The system of claim 1 wherein the surface conforms to an arbitrary shaped object.

10. The system of claim 1 wherein the antennas are arranged in a regular pattern.

11. The system of claim 1 wherein the antennas are arranged in an irregular pattern.

12. The system of claim 1 further comprising:

means for associating two antennas with the particular user when the particular user simultaneously touches two antennas.

13. The system of claim 12 wherein the two antennas define a bounding box.

14. The system of claim 1 wherein the particular user simultaneously couples multiple antennas, and further comprising:

means for estimating a centroid of the plurality of antennas.

15. The system of claim 1 wherein each receiver capacitively coupled to a different user uses near field coupling, and frequencies of the uniquely identifiable signals are substantially under 1 MHz to maximize a signal to noise ratio at the receivers.

16. The system of claim 1 wherein another user touches the particular user while the particular user touches any of the plurality of antennas, and further comprising:

means for associating the specific antenna with the particular user and the other user.

17. The system of claim 1 wherein the means for associating further comprises;

means for generating orthogonal spreading codes in the transmitter;

means for modifying the transmitted signals according to the spreading codes; and

means for separating the transmitted signals according by correlation with the spreading codes.

18. The system of claim 17 further comprising:

means for generating a pseudo random noise bit sequence using a polynomial function;

a shift register coupled to the means for generating; and

a plurality of taps coupled to the shift register to provide time delays of the pseudo random noise bit sequence and to modify the transmitted signals according to the time delayed pseudo random noise bit sequence.

19. The system of claim 1 wherein the plurality of antennas are a single resistive substrate, and a plurality of transmitters are coupled to the resistive substrate.

20. The system of claim 1 wherein the transmitted signals are driven in reverse by coupling one transmitter to each user, and coupling the antennas to a single receiver.

21. The system of claim 1 wherein each antenna is coupled to a unique transmitter and associated unique receiver to differentiate multiple simultaneous touches by a single user.

22. The system of claim 1 further including timing signals to differentiate multiple simultaneous touches by a single user.

23. A method for operating a multi-user touch system, comprising:

transmitting uniquely identifiable signals to a plurality of antennas mounted on a surface;

receiving the uniquely identifiable signals when users capacitively coupled the transmitted signal by touching the antennas; and

associating specific touched antennas with particular users when multiple users simultaneously touch any of the plurality of antennas.

24. The method of claim 23 wherein the receivers are capacitively coupled to the users via conductive chairs.

25. The method of claim 23 wherein the capacitive coupling uses near field coupling, and frequencies of the uniquely identifiable signals are under 1 MHz to maximize a signal to noise ratio at the receivers.

26. The method of claim 23 wherein the plurality of antennas are mounted on a tabletop, and further comprising:

projecting an image onto the tabletop.