Environmental compensation element of a force-sensing membrane
The disclosed subject matter provides structures, devices, and methods for environmental compensation of temperature and humidity impacts on resistive force or touch sensor devices. Accordingly, various disclosed embodiments can be configured to determine sheet resistance of a device comprising force-sensing membrane and to apply an environmental compensation factor based on the sheet resistance. Further disclosed embodiments are directed to devices, systems and methods associated with disclosed environmental compensating elements and methods related thereto.
1. A system, comprising:
a force-sensing membrane (FSM);
at least two electrical contacts of the FSM, spaced apart on and in contact with an area of force-sensing resistive (FSR) material coating on a surface of the FSM;
a two-dimensional array of electrodes associated with the FSM adapted to make electrical contact representative of physical contact with the FSM at respective locations of the two-dimensional array with a force applied to the FSM, where the at least two electrical contacts are configured to allow sheet resistance measurement of the FSM during operation of the system;
an environmental compensating element (ECE) configured to allow measurement of at least one electrical characteristic associated with the sheet resistance for determination of an environmental compensation factor to a measurement of a force applied to the FSM in operation of the system;
control circuitry electrically coupled to the at least two electrical contacts and configured to allow measurement of the at least one electrical characteristic associated with the sheet resistance for use as the environmental compensation factor;
a memory comprising computer executable instructions, algorithms, and control logic for operation and environmental compensation of the system; and
a processor configured to execute at least one of the computer executable instructions, algorithms, or control logic, wherein the at least one of the computer executable instructions, algorithms, or control logic is configured to determine a variable factor, based at least in part on the environmental compensation factor, applied to modify values in a pre-determined calibration table of the FSM to create an environmentally-compensated calibration table for the FSM.
2. The system of claim 1 , wherein the ECE comprises a conductive ink.
3. The system of claim 1 , wherein the ECE comprises a silver-based conductive ink or another low-resistance material.
4. The system of claim 1 , further comprising:
a printed circuit board (PCB) comprising the two-dimensional array of electrodes adapted to complete the electrical contact of the two-dimensional array of electrodes associated with the FSM.
5. The system of claim 4 , wherein the ECE further comprises a conductive adhesive located between at least two electrical contacts of the FSM and a corresponding set of contacts on the PCB that forms low-resistance electrical coupling between the FSM and the PCB.
6. The system of claim 5 , wherein the conductive adhesive comprises at least one of a liquid conductive adhesive or a dry film conductive adhesive.
7. The system of claim 5 , wherein the conductive adhesive comprises a conductive epoxy.
8. The system of claim 1 , wherein the control circuitry is configured to generate a voltage proportionate to the sheet resistance.
9. The system of claim 1 , wherein the at least one of the computer executable instructions, algorithms, or control logic is configured to determine the variable factor based at least in part on the sheet resistance.