Fast multi-touch noise reduction
A low-latency touch sensitive device provides a method for determining a location of a touch event thereon. The touch sensitive device row conductors and column conductors, the path of each of the row conductors crossing the path of each of the column conductors. Each of a set of orthogonal row signals are simultaneously transmitted on a respective one of at least some of the row conductors and an amount of each of the plurality of orthogonal row signals present on each of the plurality of column conductors is detected. A set of orthogonal column signals are simultaneously transmitted on a respective one of at least some of the column conductors. An amount of each of the orthogonal column signals present on each of the plurality of row conductors is detected. The detected amount of each of the plurality of orthogonal row signals and the detected amount of each of the plurality of orthogonal column signals is used to determine the location of a touch event on the device.
1. A method for noise reduction on a touch sensitive device, the touch sensitive device comprising a plurality of first conductors and a plurality of second conductors oriented in the touch sensitive device such that a touch event will cause a change in coupling between at least one of the plurality of first conductors and at least one of the plurality of second conductors, the method comprising:
a. simultaneously transmitting signals on each of the conductors in the plurality of first conductors, each of the signals being frequency orthogonal to each other signal simultaneously transmitted on the plurality of first conductors;
b. making a first counterpart measurement for each of the signals transmitted on the first conductors present on each of the plurality of second conductors;
c. simultaneously transmitting signals on each of the conductors in the plurality of second conductors, each of the signals being frequency orthogonal to each other signal simultaneously transmitted on the plurality of second conductors;
d. making a second counterpart measurement for each of the signals transmitted on the second conductors present on each of the plurality of first conductors;
e. rejecting the first and second counterpart measurements for a given pair of conductors where the first counterpart measurement for the given pair does not correspond to the second counterpart measurement for the given pair, wherein the first counterpart measurement for the given pair and the second counterpart measurement for the given pair correspond when each is reflective of a same touch event.
2. The method of claim 1 , wherein step (a) does not occur while step (c) occurs.
3. The method of claim 1 , wherein at least a portion of steps (a) and (c) occur simultaneously, and each of the signals transmitted on the first or second conductors are frequency orthogonal to each other signal transmitted on the first or second conductors.
4. The method of claim 3 , wherein steps (a) and (c) occur simultaneously, and each of the signals transmitted on the first or second conductors are frequency orthogonal to each other signal transmitted on the first or second conductors.
5. The method of claim 1 , wherein at least one of the signals transmitted on the first conductors is the same signal as at least one of the signals transmitted on the second conductors.
6. The method of claim 3 , wherein at least one of the signals transmitted on the first conductors is the same signal as at least one of the signals transmitted on the second conductors.
7. A method for noise reduction on a touch sensitive device, the touch sensitive device comprising at least two A conductors and at least two B conductors oriented in the touch sensitive device such that a touch event will cause a change in coupling between at least one of the A conductors and at least one of the B conductors, the method comprising:
a. simultaneously transmitting a first signal on a first one of the A conductors and a second signal on a second one of the A conductors, each of the first signal and the second signal being frequency orthogonal to the other;
b. making a first counterpart measurement for each of the first and second signals present on each of the B conductors;
c. simultaneously transmitting a third signal on a first one of the B conductors and a fourth signal on a second one of the B conductors, each of the third signal and the fourth signal being frequency orthogonal to the other;
d. making a second counterpart measurement for each of the third and fourth signals present on each of the A conductors;
e. rejecting the first and second counterpart measurements for a given pair of A and B conductors where the first counterpart measurement for the given pair does not correspond to the second counterpart measurement for the given pair, wherein the first counterpart measurement for the given pair and the second counterpart measurement for the given pair correspond when each is reflective of a same touch event.
8. The method of claim 7 , wherein step (a) does not occur while step (c) occurs.
9. The method of claim 7 , wherein at least a portion of steps (a) and (c) occur simultaneously, and each of the signals transmitted on the A or B conductors are frequency orthogonal to each other signal transmitted on the A or B conductors.
10. The method of claim 9 , wherein steps (a) and (c) occur simultaneously, and each of the signals transmitted on the A or B conductors are frequency orthogonal to each other signal transmitted on the A or B conductors.
11. The method of claim 7 , wherein the first signal is the same signal as the third signal.
12. The method of claim 11 , wherein the second signal is the same signal as the fourth signal.
13. A noise mitigating touch sensitive device comprising:
a. plurality of A conductors and plurality of B conductors, the A and B conductors being arranged such that a coupling therebetween differs when the touch sensitive device is not being touched, as compared to when the touch sensitive device is being touched;
b. signal generator configured to transmit each of a plurality of unique frequency orthogonal signals on each of a plurality of transmit lines, each of the signals being frequency orthogonal to each of the other signals, one group of the plurality of transmit lines being electrically connected to the plurality of A conductors, and another group of the plurality of transmit lines being electrically connected to the plurality of B conductors;
c. signal decoder configured to receive signals on each of a plurality of receiver lines and to make a measurement for each of the plurality of unique frequency orthogonal signals on each of the plurality of receiver lines, one group of the plurality of receiver lines being electrically connected to the plurality of B conductors, and another group of the plurality of receiver lines being electrically connected to the plurality of A conductors; and
d. processor for matching a first heat map derived from the measurements for each of the plurality of unique frequency orthogonal signals on each of the plurality of receiver lines being electrically connected to the A conductors to a second heat map derived from the measurements for each of the plurality of unique frequency orthogonal signals on each of the plurality of receiver lines being electrically connected to the B conductors, wherein a match is found when corresponding elements in the first and second heat map are both reflective of a same touch.
14. The noise mitigating touch sensitive device of claim 13 , wherein the signal generator is adapted to dynamically reconfigure a mapping between the plurality of unique frequency orthogonal signals and the plurality of transmit lines.