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US 9,851,845 B2Granted
Temperature compensation for transparent force sensors
AssigneeApple Inc.
InventorsJohn S. Smith, Manu Agarwal
Life of this patent
Estimating the term…
Abstract
An optically transparent force sensor element compares a force reading from a first strain-sensitive film element with a second strain-sensitive film element, having a compliant and thermally conductive intermediate layer positioned therebetween to compensate for temperature changes. While in the idle state, the optically transparent force sensor can be periodically calibrated to account for additional changes in temperature.
Claims13
An electronic device comprising:
- an input surface comprising:
- a substrate;
- a first sensor coupled to the substrate and formed from a material with a first strain-sensitive electrical property;
- and
- a second sensor positioned below and aligned with the first sensor, coupled to the substrate, and separated from the first sensor by a selected distance, the second sensor formed from a material with a second strain-sensitive electrical property;
- and
- a controller configured to obtain a measurement representing a difference between the first strain-sensitive electrical property and the second strain-sensitive electrical property.
4 more elements
An electronic device comprising:
- an input surface comprising:
- a substrate having a top surface;
- a strain sensor coupled to the substrate and comprising:
- a first and second strain-sensitive resistors arranged as a voltage divider, the first strain-sensitive resistor having a first strain-sensitive electrical property and being separated from the top surface by a first distance and the second strain-sensitive resistor having a second strain-sensitive electrical property and being separated from the top surface by a second distance;
- and
- a common node coupled to both the first and second strain-sensitive resistor;
- and
- a controller configured to perform the operations of:
- injecting a selected current into the common node;
- and
- measuring a voltage between the common node and ground, the voltage representing a difference between the first strain-sensitive electrical property and the second strain-sensitive electrical property.
8 more elements
Dependencies are inferred from the claim text.