Multi-user touch surface

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 user when multiple users simultaneously touch any of the antennas.

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.  
 
     
     
       27. A multi- user touch system, comprising:      a surface including a plurality of touch sensitive elements:        a transmitter configured to transmit a unique signal to each touch sensitive element;        a plurality of receivers, each receiver connected to a different user: and        means for associating a particular touch sensitive element with a particular user touching the particular touch sensitive element, based on the transmitted unique signals, when multiple users simultaneously touch any of the plurality of touch sensitive elements.     
     
     
       28. The system of  claim 27 , in which the particular user touches a subset of the plurality of touch sensitive elements, and further comprising:
   means for associating each touch sensitive element in the subset with the particular user.     
     
     
       29. The system of  claim 28 , in which the subset includes more than one touch sensitive element. 
     
     
       30. The system of  claim 28 , in which each touch sensitive element has an associated location on the surface. 
     
     
       31. The system of  claim 27 , in which the plurality of touch sensitive elements are arranged in rows and columns on the surface. 
     
     
       32. The system of  claim 27 , in which the surface is constructed as a printed circuit board further comprising:
   a first insulator layer:        a row layer;        a second insulator layer;        a column layer; and        a mechanical support layer.     
     
     
       33. The system of  claim 27 , in which locations of the plurality of touch sensitive elements are unambiguously associated with the particular user for each user. 
     
     
       34. The system of  claim 27 , in which the touch sensitive elements are arranged in a regular pattern. 
     
     
       35. The system of  claim 27 , in which the touch sensitive elements are arranged in an irregular pattern. 
     
     
       36. The system of  claim 30 , further comprising:
   means for determining a centroid of the locations of the touch sensitive elements in the subset.     
     
     
       37. The system of  claim 30 , further comprising:
   means for determining a bounding box associated with the locations of the touch sensitive elements in the subset.     
     
     
       38. The system of  claim 27 , further comprising:
   means for projecting an image on the surface while the multiple users simultaneously touch any of the plurality of touch sensitive elements.     
     
     
       39. The system of  claim 27 , in which each touch sensitive element has an associated location on the surface, and further comprising:
   means for projecting an image on the surface while the multiple users simultaneously touch any of the plurality of touch sensitive elements; and        means for associating the location of the particular touch sensitive element with the particular user and a corresponding location in the image.     
     
     
       40. The system of  claim 27 , further comprising:
   a conductive pointer held by the particular user to touch the particular touch sensitive element.     
     
     
       41. The system of  claim 27 , further comprising:
   a conductive chair configured to connect each different user to the receiver associated with the different user.     
     
     
       42. A multi- user touch system, comprising:      a surface including a plurality of antennas mounted thereon;        a transmitter configured to transmit uniquely identifiable signals to each antenna:        a plurality of receivers, each receiver capacitively coupled to a different user, the receivers configured to receive the uniquely identifiable signals: and        means for associating a specific antenna with a particular user when multiple users simultaneously touch any of the plurality of antennas.     
     
     
       43. The system of  claim 42  wherein the surface conforms to an arbitrary shaped object. 
     
     
       44. The system of  claim 42  further comprising:
   means for associating two antennas with the particular user when the particular user simultaneously touches two antennas.     
     
     
       45. The system of  claim 42  wherein the two antennas define a bounding box. 
     
     
       46. The system of  claim 42  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.     
     
     
       47. The system of  claim 42  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.     
     
     
       48. The system of  claim 42  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 by correlation with the spreading codes.     
     
     
       49. The system of  claim 42  wherein the plurality of antennas are a single resistive substrate, and a plurality of transmitters are coupled to the resistive substrate. 
     
     
       50. The system of  claim 42  wherein the transmitted signals are driven in reverse by coupling one transmitter to each user, and coupling the antennas to a single receiver. 
     
     
       51. The system of  claim 42  wherein each antenna is coupled to a unique transmitter and an associated unique receiver to differentiate multiple simultaneous touches by a single user. 
     
     
       52. The system of  claim 42  wherein timing signals differentiate multiple simultaneous touches by a single user. 
     
     
       53. A method for operating a multi- user touch system, comprising:      transmitting uniquely identifiable signals to a plurality of touch elements mounted on a surface; and        associating specific touched elements with particular users when multiple users simultaneously touch any of the plurality of touch elements.     
     
     
       54. The method of  claim 53  wherein the plurality of touch elements are capacitively coupled to the users via conductive chairs. 
     
     
       55. A multi- user touch system, comprising:      a plurality of transmitters, each transmitter connected to a different user and each transmitter configured to transmit a unique signal associated with each different user connected to the transmitter;        a surface including a plurality of touch sensitive elements;        a receiver connected to each of the plurality of touch sensitive elements; and        means for associating a particular touch sensitive element with a particular user touching the particular touch sensitive element, based on the transmitted unique signals, when multiple users simultaneously touch any of the plurality of touch sensitive elements.