US 11,927,645 B2
Detecting sensitivity faults in capacitive sensors by using pull-in functionality
Dan-Ioan-Dumitru Stoica, Buchare (RO); Cesare Buffa, Villach (AT); Alessandro Caspani, Villach (AT); Constantin Crisu, Bucharest (RO); Victor Popescu-Stroe, Bucharest (RO); and Bernhard Winkler, Regensburg (DE)
Assigned to Infineon Technologies AG, Neubiberg (DE)
Filed by Infineon Technologies AG, Neubiberg (DE)
Filed on Sep. 1, 2021, as Appl. No. 17/463,753.
Prior Publication US 2023/0064937 A1, Mar. 2, 2023
Int. Cl. G01R 31/64 (2020.01); G01H 11/06 (2006.01); G01L 9/12 (2006.01); G01R 27/26 (2006.01); G01R 35/00 (2006.01)
CPC G01R 31/64 (2020.01) [G01R 27/2605 (2013.01); G01R 35/00 (2013.01); G01H 11/06 (2013.01); G01L 9/12 (2013.01)] 26 Claims
OG exemplary drawing
 
1. A capacitive sensor, comprising:
a first electrode structure;
a second electrode structure that is counter to the first electrode structure, wherein the second electrode structure is movable relative to the first electrode structure in response to an external force acting thereon, wherein the second electrode structure is capacitively coupled to the first electrode structure to form a first capacitor having a first capacitance that changes with a change in a distance between the first electrode structure and second electrode structure, wherein the first capacitance is representative of the external force,
wherein a pull-in event occurs when the first electrode structure is in direct contact with the second electrode structure causing the first capacitance to be equal to or greater than a pull-in capacitance and a non-pull-in event occurs when the first electrode structure is not in direct contact with the second electrode structure causing the first capacitance to be less than the pull-in capacitance;
a signal generator configured to apply a first electrical signal at an input or at an output of the first capacitor to induce a first voltage transient response at the output of first capacitor, wherein the first electrical signal is a pull-in signal configured to induce a pull-in event in the absence of a fault or a non-pull-in signal configured induce a non-pull-in event in the absence of a fault; and
a diagnostic circuit configured to detect a fault in the capacitive sensor by measuring a first time constant of the first voltage transient response and detecting the fault based on the first time constant and based on whether the first electrical signal is the pull-in signal or the non-pull-in signal.