System for detecting and characterizing inputs on a touch sensor

A system for detecting and characterizing inputs on a touch sensor surface comprising:

• a touch sensor comprising:
• a substrate;
• an array of sense electrodes patterned across the substrate;
• and
• a resistive layer arranged over the substrate and comprising a material exhibiting changes in local contact resistance responsive to variations in magnitude of force communicated into the resistive layer;
• a force-spreading layer arranged over the resistive layer, defining the touch sensor surface, and distributing a force applied on and normal to the touch sensor surface laterally and into the resistive layer;
• and
• a controller configured to:
• detect an input on the force-spreading layer based on local changes in resistance within the resistive layer measured by a subset of sense electrodes in the touch sensor;
• and
• characterize the first force input as one of a stylus input type and a non-stylus input type based on a ratio of a detected force magnitude to a detected area of the first force input on the force-spreading layer.

A method for detecting and characterizing inputs on a touch sensor surface of an input device, the method comprising:

• at a first time, scanning an array of sense electrodes, arranged under the touch sensor surface, at a first resolution to generate a first force image;
• detecting a first force input in the first force image;
• in response to a first geometry dimension of the first force input exceeding a first threshold, characterizing the first force input as a non-stylus input type;
• in response to the first geometry dimension of the first force input remaining below the first threshold:
• at a second time succeeding the first time, scanning the array of sense electrodes at a second resolution greater than the first resolution to generate a second force image;
• detecting a second force input in the second force image proximal the first force input;
• and
• in response to a second ratio of a second force magnitude of the second force input to a second geometry dimension of the second force input exceeding a second threshold, characterizing the first force input as a stylus input type;
• and
• outputting, to a computing device coupled to the input device, a location and a specification for a type of the first force input.