Pre-loaded force sensing resistor and method
First Claim
1. A force sensing resistor (FSR) comprising:
- a first substrate having first and second electrically conductive traces on an inner surface, wherein the traces are electrically separated from one another; and
a second substrate having a resistive layer on an inner surface;
wherein the substrates are subjected to a biasing force such that during the biasing force the substrates are in contact with one another with the resistive layer contacting and electrically connecting the traces together with an electrical resistance that inversely depends on the biasing force;
wherein while an external force is applied to one of the substrates in a direction toward the other substrate, the substrates contact one another with a total force which is the sum of the biasing force and the external force with the resistive layer contacting and electrically connecting the traces together with an electrical resistance that inversely depends on the total force;
wherein the biasing force is present regardless of either the presence or absence of the external force.
1 Assignment
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Accused Products
Abstract
A force sensing resistor (FSR) includes a substrate having separated electrically conductive traces and another substrate having a resistive layer in which the substrates are subjected to a biasing force such that the substrates contact one another with the resistive layer electrically connecting the traces with a resistance inversely dependent on the biasing force. Upon an external force applied towards a substrate, the substrates contact one another with a total force which is the sum of the forces with the resistive layer electrically connecting the traces with a resistance inversely dependent on the total force. An FSR output which is a function of the resistance is measured. Whether a change in magnitude of the FSR output during a time interval is greater than a threshold is determined. A touch applied on the FSR is detected during the time interval if the change is greater than the threshold.
38 Citations
20 Claims
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1. A force sensing resistor (FSR) comprising:
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a first substrate having first and second electrically conductive traces on an inner surface, wherein the traces are electrically separated from one another; and a second substrate having a resistive layer on an inner surface; wherein the substrates are subjected to a biasing force such that during the biasing force the substrates are in contact with one another with the resistive layer contacting and electrically connecting the traces together with an electrical resistance that inversely depends on the biasing force; wherein while an external force is applied to one of the substrates in a direction toward the other substrate, the substrates contact one another with a total force which is the sum of the biasing force and the external force with the resistive layer contacting and electrically connecting the traces together with an electrical resistance that inversely depends on the total force; wherein the biasing force is present regardless of either the presence or absence of the external force. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for a force sensing resistor (FSR) having first and second substrates with the first substrate including electrically conductive and separated traces and the second substrate including a resistive layer in which the substrates are continuously subjected to a biasing force such that the substrates contact one another with the resistive layer contacting and electrically connecting the traces together with an electrical resistance that inversely depends on the biasing force, wherein, upon an external force being applied to one of the substrates in a direction toward the other substrate, the substrates contact one another with a total force which is the sum of the biasing force and the external force with the resistive layer contacting and electrically connecting the traces together with an electrical resistance that inversely depends on the total force, the method comprising:
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measuring samples of an output of the FSR periodically over a time period in which the FSR output is a function of the electrical resistance; determining whether a change in magnitude between at least two consecutive FSR output samples during a first time interval of the time period is greater than a threshold; and detecting an external touch applied on the FSR during the first time interval if the change in magnitude between the at least two consecutive FSR output samples during the first time interval is greater than the threshold. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A method for a force sensing resistor (FSR) having first and second substrates in which the first substrate includes electrically conductive and separated traces and the second substrate includes a resistive layer and in which the substrates are continuously subjected to a biasing force such that the substrates contact one another with the resistive layer contacting and electrically connecting the traces together with an electrical resistance that inversely depends on the biasing force, wherein, upon an external force being applied to one of the substrates in a direction toward the other substrate, the substrates contact one another with a total force which is the sum of the biasing force and the external force with the resistive layer contacting and electrically connecting the traces together with an electrical resistance that inversely depends on the total force, the method comprising:
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measuring an output of the FSR over a time period in which the FSR output is a function of the electrical resistance; determining whether a change in magnitude of the FSR output during a first time interval of the time period is greater than a threshold; and detecting an external touch applied on the FSR during the first time interval if the change in magnitude of the FSR output during the first time interval is greater than the threshold. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification