Adaptive mechanical change compensation for force detector
AssigneeSynaptics Incorporated
InventorsYing WANG, Adam L. SCHWARTZ, Shubha RAMAKRISHNAN
Life of this patent
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Abstract
A capacitive sensing device is configured to detect force being applied to an input surface of the device by an input object, in addition to the position of the input object using touch sensing methods. Embodiments generate a compensation factor that is used to determine the force information in order to compensate for physical changes to the capacitive sensing device over time, air-gap non-uniform distribution, and other mechanical variations and changes.
Claims20
A method of operating a capacitive sensing device having a plurality of sensor electrodes and at least one force electrode, the method comprising:
- storing a baseline capacitance of the force electrode without a force applied to an input surface of the capacitive sensing device, wherein at least a portion of the plurality of sensor electrodes are configured to deflect relative to at least one force electrode;
- determining a change in capacitance of the force electrode caused by an input object contacting the input surface and based on a current capacitance of the force electrode and the stored baseline capacitance;
- determining a mechanical change compensation factor associated with the capacitive sensing device based on a pre-determined calibration force, a change in capacitance of the force electrode in response to the pre-determined calibration force applied to the input surface, and a calibration baseline capacitance;
- and
- determining force information for the input object contacting the input surface based on at least the mechanical change compensation factor, the baseline capacitance, and the change in capacitance.
A processing system for a capacitive sensing device having an input surface, wherein the capacitive sensing device comprises at least one force electrode and a plurality of sensor electrodes, at least a portion of the plurality of sensor electrodes are configured to deflect towards the at least one force electrode, the processing system comprising:
- a sensor module including sensor circuitry configured to be coupled to the plurality of sensor electrodes and the at least one force electrode, wherein the sensor module is configured to:
- store a baseline capacitance of the force electrode without a force applied to the input surface of the capacitive sensing device;
- determine a change in capacitance of the force electrode caused by an input object contacting the input surface and based on a current capacitance of the force electrode and the stored baseline capacitance;
- determine a mechanical change compensation factor associated with the capacitive sensing device based on a pre-determined calibration force, a change in capacitance of the force electrode in response to the pre-determined calibration force applied to the input surface, and a calibration baseline capacitance;
- and
- determine force information for the input object contacting the input surface based on at least the mechanical change compensation factor, the baseline capacitance, and the change in capacitance.
A capacitive sensing device having an input surface, the capacitive sensing device comprising:
- at least one force electrode;
- a plurality of sensor electrodes, wherein at least a portion of the plurality of sensor electrodes configured to deflect towards the at least one force electrode;
- and
- a processing system coupled to the plurality of sensor electrodes and the at least one force electrode, the processing system comprising a sensor module having sensor circuitry, wherein the sensor module is configured to:
- store a baseline capacitance of the force electrode without a force applied to the input surface of the capacitive sensing device;
- determine a change in capacitance of the force electrode caused by an input object contacting the input surface and based on a current capacitance of the force electrode and the stored baseline capacitance;
- determine a mechanical change compensation factor associated with the capacitive sensing device based on a pre-determined calibration force, a change in capacitance of the force electrode in response to the pre-determined calibration force applied to the input surface, and a calibration baseline capacitance;
- and
- determine force information for the input object contacting the input surface based on at least the mechanical change compensation factor, the baseline capacitance, and the change in capacitance.
Dependencies are inferred from the claim text.