US 11,947,756 B2
Sensor signal correction
Josh Sanz-Robinson, Austin, TX (US); Siddharth Maru, Austin, TX (US); and Tejasvi Das, Austin, TX (US)
Assigned to Cirrus Logic Inc., Austin, TX (US)
Filed by Cirrus Logic International Semiconductor Ltd., Edinburgh (GB)
Filed on Oct. 18, 2022, as Appl. No. 17/968,565.
Application 17/968,565 is a continuation of application No. 17/097,384, filed on Nov. 13, 2020, granted, now 11,520,436.
Prior Publication US 2023/0043516 A1, Feb. 9, 2023
Int. Cl. G06F 3/041 (2006.01); G06F 3/02 (2006.01); G06F 3/01 (2006.01)
CPC G06F 3/0418 (2013.01) [G06F 3/02 (2013.01); G06F 3/0414 (2013.01); G06F 3/016 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A correction unit for use in a sensor system, the sensor system comprising a force sensor configured to output a sensor signal indicative of a temporary mechanical distortion of a material under an applied force, the correction unit configured, based on the sensor signal, to:
measure an elapsed time from a start of a user press operation when a user applies a force to the force sensor, the start of the user press operation defined by when the sensor signal crosses or exceeds a threshold value as it rises from a value below the threshold value;
calculate an estimation signal which estimates an effect of the applied force on how the material will return towards an undistorted form upon a substantial reduction or removal of the applied force, wherein the estimation signal is calculated to rise during the user press operation with its value dependent on the elapsed time; and
generate a corrected signal based on the estimation signal;
wherein the correction unit is configured, based on a determinative magnitude being a magnitude of the sensor signal or the corrected signal, to calculate a compensation signal as:
when the determinative magnitude is above a first threshold, the estimation signal;
when the determinative magnitude is below a second threshold, the sensor signal; and
when the determinative magnitude is between the first and second thresholds, a weighted sum of the sensor signal and the estimation signal dependent on a position of the determinative magnitude between the first and second thresholds; and
wherein:
the compensation signal is an estimated baseline signal; and
the correction unit is configured to generate the corrected signal by subtracting the estimated baseline signal from the sensor signal, including at the end of the user press operation when the sensor signal value drops rapidly as the applied force is substantially reduced or removed,
whereby the sensor signal need drop less far to meet the estimated baseline signal at the end of the user press operation than if the estimation signal were not calculated to rise during the user press operation dependent on the elapsed time.