Matrix sensor for image touch sensing

An input device comprising:

• a plurality of sensor electrodes comprising a first sensor electrode and a second sensor electrode;
• a field shaping electrode;
• and
• a processing system coupled to the plurality of sensor electrodes and the field shaping electrode, the processing system configured to:
• drive and receive with each of the plurality of sensor electrodes to simultaneously acquire measurements of changes in absolute capacitance between each of the plurality of sensor electrodes and an input object;
• determine positional information for the input object in a sensing region of the capacitive sensing device based on the measurements of changes in absolute capacitance;
• and
• selectively operate the field shaping electrode in a first mode when the input object is determined to be in a first region of the sensing region based and in a second mode when the input object is determined to be in a second region of the sensing region, wherein the first region of the sensing region is between the second region and an input surface of the sensing device, wherein during at least one of the first mode and the second mode the field shaping electrode is configured to substantially isolate the first sensor electrode from the second sensor electrode.

A method for capacitive sensing, the method comprising:

• driving and receiving with each of a plurality of sensor electrodes to simultaneously acquire measurements of changes in absolute capacitance between each of the plurality of sensor electrodes and an input object;
• determining positional information for the input object in a sensing region of a capacitive sensing device based on the measurements of changes in absolute capacitance;
• and
• selectively operating a field shaping electrode in a first mode when the input object is determined to be in a first region of the sensing region based and in a second mode when the input object is determined to be in a second region of the sensing region, wherein the first region of the sensing region is between the second region and an input surface of the sensing device, wherein during at least one of the first mode and the second mode the field shaping electrode is configured to substantially isolate the first sensor electrode from the second sensor electrode.