TWO-DIMENSIONAL TOUCH SENSORS

• US 20100289754A1
• Filed: 05/14/2009
• Published: 11/18/2010
• Est. Priority Date: 05/14/2009
• Status: Active Grant

• Current Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Original Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Inventors: Pickett, Daniel, Ard, Christopher, Simmons, Martin John, Sleeman, Peter
• Granted Patent: US 8,154,529 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 2200/1614 Image rotation following screen orientation, e.g. switching from landscape to portrait mode
• CPC Class Codes: G06F 2203/04808 Several contacts: gestures triggering a specific function, e.g. scrolling, zooming, right-click, when the user establishes several contacts with the surface simultaneously; e.g. using several fingers or a combination of fingers and pen
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• 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: G06F 3/04883 for inputting data by handwriting, e.g. gesture or text

Abstract

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. This allows many novel gestures to be provided, such as single finger “drag and zoom” and single finger “drag and rotate”. It also allows for correction of systematic human error in the placement of finger touches on virtual keys.

Claims

1. A method of sensing touches on a touch sensor, the method comprising:

providing a touch sensor having a two-dimensional array of sensing nodes distributed over a sensing area;

acquiring a frame of touch signal values from the sensing nodes;

processing the touch signal values to detect at least one touch in the frame, each touch being formed of a contiguous group of one or more sensing nodes;

computing for each touch its touch location on the sensing area by processing the touch signal values of the touch;

computing for each touch a touch angle indicative of orientation of the touch on the sensing area by processing the touch signal values of the touch; and

outputting for each frame frame data including the touch location and the touch angle.

2. The method of claim 1, further comprising:

computing for each touch a touch ellipticity factor indicative of how elongate a shape is possessed by the touch by processing the touch signal values of the touch; and

outputting for each frame as part of the frame data the touch ellipticity factor.

3. The method of claim 2, 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.

4. The method of claim 1, further comprising:

providing a gesture processor arranged to receive the frame data from the touch sensor and operable to process the frame data over time, wherein the gesture processor runs a gesture processing algorithm which identifies gestures from the frame data, and outputs gesture data.

5. The method of claim 4, wherein the gesture processing algorithm includes recognition for at least one gesture having a parameter with a mapping to the touch angle.

6. The method of claim 4, 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.

7. The method of claim 4, wherein the gesture recognition algorithm includes recognition for at least one gesture based on analysis of the touch angle and the touch location over time such that motion of the touch location in a direction generally transverse to the touch angle of the touch is recognized as a lateral sliding or rocking motion of a finger.

8. The method of claim 2, further comprising:

providing a gesture processor arranged to receive the frame data from the touch sensor and operable to process the frame data over time, wherein the gesture processor runs a gesture processing algorithm which identifies gestures from the frame data, and outputs gesture data.

9. The method of claim 8, wherein the gesture processing algorithm includes recognition for at least one gesture having a parameter with a mapping to the touch ellipticity factor.

10. The method of claim 8, wherein the gesture recognition algorithm includes recognition for at least one gesture which jointly processes the touch angle and touch ellipticity factor, using the magnitude of the touch ellipticity factor to determine angular precision of the touch angle.

11. The method of claim 8, 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.

12. The method of claim 8, wherein the gesture recognition 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.

13. The method of claim 1, wherein the touch sensor is a capacitive touch sensor.

14. A touch sensor, comprising:

a two-dimensional array of sensing nodes distributed over a sensing area;

a measurement circuit operable to acquire frames of touch signal values from the sensing nodes; and

a processing unit operable to;

process the touch signal values to detect at least one touch in the frame, each touch being formed of a contiguous group of one or more sensing nodes;

compute for each touch its touch location on the sensing area by processing the touch signal values of the touch;

compute for each touch a touch angle indicative of orientation of the touch on the sensing area by processing the touch signal values of the touch; and

output for each frame frame data including the touch location and the touch angle.

15. The touch sensor of claim 14, wherein the processing unit is further operable to:

compute for each touch a touch ellipticity factor indicative of how elongate a shape is possessed by the touch by processing the touch signal values of the touch; and

output for each frame as part of the frame data the touch ellipticity factor.

16. The touch sensor of claim 14, in combination with:

a gesture processor arranged to receive the frame data from the touch sensor and operable to process the frame data over time, wherein the gesture processor is operable to run a gesture processing algorithm to identify gestures from the frame data, and output gesture data.