Simultaneous sensing arrangement
Multi-touch touch-sensing devices and methods are described herein. The touch sensing devices can include multiple sense points, each located at a crossing of a drive line and a sense line. In some embodiments, multiple drive lines may be simultaneously or nearly simultaneously stimulated with drive signals having unique characteristics, such as phase or frequency. A sense signal can occur on each sense line that can be related to the drive signals by an amount of touch present at sense points corresponding to the stimulated drive lines and the sense line. By using processing techniques based on the unique drive signals, an amount of touch corresponding to each sense point can be extracted from the sense signal. The touch sensing methods and devices can be incorporated into interfaces for a variety of electronic devices such as a desktop, tablet, notebook, and handheld computers, personal digital assistants, media players, and mobile telephones.
1. A method of deriving touch information from a touch sensitive surface, the touch sensitive surface comprising a plurality of sensing points, a sensing point being located at a crossing of a drive line and a sense line, the method comprising:
performing a first scan in a first region of the touch sensitive surface to determine whether a touch is present within the first region, the first region corresponding to a first plurality of drive lines, wherein the first scan in the first region comprises:
simultaneously stimulating a plurality of drive lines corresponding to the first region with one or more first drive signals;
sensing first sense signals on a plurality of sense lines, wherein the first sense signals are related to the one or more first drive signals by touch or proximity of one or more objects to one or more sensing points located at a crossing of the plurality of drive lines and the at least one sense line; and
determining whether a touch is present within the first region based on the first sense signals;
when the touch is present in the first region, performing a second scan in the first region, wherein performing the second scan in the first region comprises:
further stimulating the plurality of drive lines with a plurality of second drive signals;
further sensing second sense signals on the plurality of sense lines, wherein the second sense signals are related to the plurality of second drive signals by touch or proximity of the one or more objects to the one or more sensing points; and
deriving touch information for sensing points corresponding to the first region from the second sense signals; and
when the touch is not present in the first region, performing the first scan in a second region of the touch sensitive surface, wherein the second region corresponds to a second plurality of drive lines.
2. The method of claim 1 , wherein the one or more first drive signals have the same frequency and phase.
3. The method of claim 1 , wherein determining whether a touch is present within the first region comprises examining DC content of the sense signals.
4. A touch sensing device comprising: circuitry configured to:
perform a first scan in a first region of the touch sensitive surface to determine whether a touch is present within the first region, the first region corresponding to a first plurality of drive lines, wherein the first scan in the first region comprises:
simultaneously stimulating a plurality of drive lines corresponding to the first region with one or more first drive signals;
sensing first sense signals on a plurality of sense lines, wherein the first sense signals are related to the one or more first drive signals by touch or proximity of one or more objects to one or more sensing points located at a crossing of the plurality of drive lines and the plurality of sense lines; and
determining whether the touch is present within the first region based on the first sense signals;
perform a second scan in the first region when the touch is present in the first region during the first scan, wherein performing the second scan in the first region comprises:
further simultaneously stimulating the plurality of drive lines with a plurality of second drive signals;
further sensing second sense signals on the plurality of sense lines, wherein the second sense signals are related to the plurality of second drive signals by touch or proximity of the one or more objects to the one or more sensing points; and
deriving touch information for sensing points corresponding to the first region from the second sense signals; and
perform the first scan in a second region of the touch sensitive surface when the touch is not present in the first region, wherein the second region corresponds to a second plurality of drive lines.
5. The touch sensing device of claim 4 , wherein the one or more first drive signals have the same frequency and phase.
6. The touch sensing device of claim 4 , wherein determining whether the touch is present within the first region comprises examining DC content of the first sense signals.
7. A touch sensing system comprising: a touch sensitive surface comprising a plurality of sensing nodes; and
circuitry configured to:
perform a plurality of first scans in a plurality of regions of the touch sensitive surface to detect an object touching or proximate to one or more of the plurality of regions of the touch sensitive surface, each of the plurality of regions corresponding to a plurality of drive electrodes, wherein a first scan in a respective region of the plurality of regions comprises:
simultaneously stimulating a plurality of drive electrodes corresponding to the respective region with one or more first drive signals;
sensing one or more first sense signals on one or more sense electrodes, wherein the one or more first sense signals are generated in response to stimulating the plurality of drive electrodes; and
detecting the object touching or in proximity to the respective region from the one or more first sense signals; and
when an objected is detected touching or in proximity to the one or more of the plurality of regions of the touch sensitive surface, perform one or more second scans in the one or more of the plurality of regions, wherein performing a second scan in the respective region of the plurality of regions comprises:
in response to detecting, during one or more of the plurality of first scans, the object touching or in proximity to the respective region, simultaneously stimulating a plurality of drive electrodes corresponding with the respective region with a plurality of second drive signals;
sensing one or more second sense signals at the one or more sense electrodes, wherein the one or more second sense signals are generated in response to stimulating the plurality of drive electrodes corresponding with the respective region; and
deriving results for a subset of the plurality of sense nodes corresponding to the respective region based on the one or more second sense signals.
8. The touch sensing system of claim 7 , wherein a sensing node is associated with at least one drive electrode and at least one sense electrode.
9. The touch sensing system of claim 7 , wherein the one or more first drive signals have the same frequency and phase.
10. The touch sensing system of claim 7 , wherein detecting the object touching or in proximity to the respective region comprises examining DC content of the one or more first sense signals.