Two-dimensional touch sensors
In a touch sensor, as well as providing touch position data, additional data is provided on the shape of the touch. This is achieved by having sampling nodes on a finer mesh than the size of the actuating object, typically a finger, so each finger touch activates a group of adjacent nodes on the sensor. In this way, each touch has a shape formed by the activated nodes. The shape allows the touch sensor to report an angle with each touch and data indicating how elongate the touch is, preferably both together as a vector in which the direction of the vector gives the angle and the magnitude of the vector gives the ellipticity. For each frame of data collected from the sensor array, the sensor outputs an (x, y) coordinate of touch position and a further (x, y) coordinate of a shape vector.
1. A method of sensing touches on a touch sensor, the method comprising:
acquiring, by a computer processing unit, a frame comprising a plurality of touch signal values detected by a two-dimensional array of sensing nodes distributed over a sensing area of a touch sensor;
detecting, by the computer processing unit, at least one touch in the frame, each touch being formed of a contiguous group of sensing nodes;
based on the touch signal values associated with the contiguous group of sensing nodes, computing, for each detected touch, a touch location on the sensing area;
based on the touch signal values associated with the contiguous group of sensing nodes, computing, for each detected touch, a touch angle indicative of orientation of the touch on the sensing area;
computing, for each detected touch, a touch ellipticity factor indicative of how elongate a shape is possessed by the touch by processing the touch signal values associated with the contiguous group of sensing nodes forming the touch;
outputting, by the computer processing unit, frame data including the touch location, the touch angle, and the ellipticity factor; and
identifying, using a gesture processing algorithm, gestures from the frame data, and wherein the gesture processing algorithm includes recognition for at least one gesture having a parameter with a mapping to a magnitude of the touch ellipticity factor, the gesture processing algorithm jointly processing the touch angle and the magnitude of the touch ellipticity factor to determine angular precision of the touch angle.
2. The method of claim 1 , wherein detecting the at least one touch in the frame comprises identifying a node having a signal value that is higher than each of the plurality of signal values and that is greater than the threshold value.
3. The method of claim 1 , further comprising identifying, using a gesture processing algorithm, gestures from the frame data, and wherein the gesture processing algorithm includes recognition for at least one gesture having a parameter with a mapping to the touch angle.
4. The method of claim 1 , further comprising identifying, using a gesture processing algorithm, gestures from the frame data, and wherein the gesture processing algorithm is operable to determine whether the touch is from a left hand or a right hand based on the touch angle.
5. The method of claim 1 , wherein the touch location is translated by a correction distance and in a correction direction determined respectively from the touch ellipticity factor and the touch angle.
6. The method of claim 1 , further comprising identifying, using a gesture processing algorithm, gestures from the frame data, and wherein the gesture processing algorithm is operable to determine whether the touch is from a thumb or a finger based on the touch ellipticity factor.
7. The method of claim 1 , further comprising identifying, using a gesture processing algorithm, gestures from the frame data, and wherein the gesture processing algorithm includes recognition for at least one gesture based on analysis of the touch ellipticity factor and touch location over time such that change in the touch ellipticity factor while the touch location is relatively constant is recognized as a vertical rocking motion of a finger in which the angle of the finger to the plane of the sensing area is being varied.
8. A touch sensor, comprising:
a two-dimensional array of sensing nodes distributed over a sensing area;
a measurement circuit operable to acquire a frame comprising a plurality of touch signal values from the two-dimensional array of sensing nodes; and
a processing unit operable to:
detect at least one touch in the frame, each touch being formed of a contiguous group of sensing nodes;
based on the touch signal values associated with the contiguous group of sensing nodes, compute, for each detected touch, a touch location on the sensing area;
based on the touch signal values associated with the contiguous group of sensing nodes, compute, for each detected touch, a touch angle indicative of orientation of the touch on the sensing area;
compute, for each detected touch, a touch ellipticity factor indicative of how elongate a shape is possessed by the touch by processing the touch signal values associated with the contiguous group of sensing nodes forming the touch;
output frame data including the touch location, the touch angle, and the ellipticity factor; and
identifying, using a gesture processing algorithm, gestures from the frame data, and wherein the gesture processing algorithm includes recognition for at least one gesture having a parameter with a mapping to a magnitude of the touch ellipticity factor, the gesture processing algorithm jointly processing the touch angle and the magnitude of the touch ellipticity factor to determine angular precision of the touch angle.
9. The touch sensor of claim 8 , wherein the processing unit is further operable to detect the at least one touch in the frame by identifying a node having a signal value that is higher than each of the plurality of signal values and that is greater than the threshold value.
10. The touch sensor of claim 8 , wherein the processing unit is further operable to use a gesture processing algorithm to identify gestures from the frame data, and wherein the gesture processing algorithm includes recognition for at least one gesture having a parameter with a mapping to the touch angle.
11. The touch sensor of claim 8 , wherein the processing unit is further operable to use a gesture processing algorithm to identify gestures from the frame data, and wherein the gesture processing algorithm is operable to determine whether the touch is from a left hand or a right hand based on the touch angle.
12. The touch sensor of claim 8 , wherein the touch location is translated by a correction distance and in a correction direction determined respectively from the touch ellipticity factor and the touch angle.
13. The touch sensor of claim 8 , wherein the processing unit is further operable to use a gesture processing algorithm to determine whether the touch is from a thumb or a finger based on the touch ellipticity factor.
14. The touch sensor of claim 8 , wherein the processing unit is further operable to use a gesture processing algorithm to identify gestures from the frame data, and wherein the gesture processing algorithm includes recognition for at least one gesture based on analysis of the touch ellipticity factor and touch location over time such that change in the touch ellipticity factor while the touch location is relatively constant is recognized as a vertical rocking motion of a finger in which the angle of the finger to the plane of the sensing area is being varied.
15. A method of sensing touches on a touch sensor, the method comprising:
acquiring, by a computer processing unit, a frame comprising a plurality of touch signal values detected by a two-dimensional array of sensing nodes distributed over a sensing area of a touch sensor;
identifying, as a primary node, a node within a group of contiguous sensing nodes that is associated with a highest touch signal value;
associating the primary node with a touch;
identifying at least one secondary node that is a direct neighbor of the primary node and that is associated with the touch, the primary node and the at least one secondary node forming a contiguous group of sensing nodes being associated with the touch;
computing, for the touch, a touch location on the sensing area;
computing, for the touch, a touch angle indicative of orientation of the touch on the sensing area;
computing, for each detected touch, a touch ellipticity factor indicative of how elongate a shape is possessed by the touch by processing the touch signal values associated with the contiguous group of sensing nodes forming the touch; and
outputting, by the computer processing unit, frame data including the touch location, the touch angle, and the ellipticity factor; and
identifying, using a gesture processing algorithm, gestures from the frame data, and wherein the gesture processing algorithm includes recognition for at least one gesture having a parameter with a mapping to a magnitude of the touch ellipticity factor, the gesture processing algorithm jointly processing the touch angle and the magnitude of the touch ellipticity factor to determine angular precision of the touch angle.