Patent ID: 7084860

Claim:
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.