US 11,775,120 B2
Combined capacitive and piezoelectric sensing in a human machine interface
Jan Morten Braathen, Redmond, WA (US); Dennis Patrick Lehman, Garland, TX (US); Miroslav Oljaca, Allen, TX (US); Maxwell G Robertson, Dallas, TX (US); and Merril Newman, Schaumburg, IL (US)
Assigned to TEXAS INSTRUMENTS INCORPORATED, Dallas, TX (US)
Filed by Texas Instruments Incorporated, Dallas, TX (US)
Filed on Oct. 20, 2021, as Appl. No. 17/506,139.
Claims priority of provisional application 63/142,604, filed on Jan. 28, 2021.
Prior Publication US 2022/0236816 A1, Jul. 28, 2022
Int. Cl. G06F 3/044 (2006.01); G06F 3/041 (2006.01)
CPC G06F 3/044 (2013.01) [G06F 3/0414 (2013.01)] 21 Claims
OG exemplary drawing
 
1. An apparatus, comprising:
capacitive measurement circuitry, coupled to one or more capacitor input terminals, and comprising a gain stage configured to amplify a signal to generate an amplified signal corresponding to a capacitance at the one or more capacitor input terminals by a gain level;
piezoelectric measurement circuitry coupled to one or more piezoelectric terminals;
gain control circuitry coupled to the piezoelectric measurement circuitry and the capacitive measurement circuitry, and configured to:
increase the gain level of the gain stage from a first level to a second level for a selected duration responsive to the piezoelectric measurement circuitry receiving an input signal representing a user input from at least one of the one or more piezoelectric terminals to cause the gain stage to generate the amplified signal with the second level,
after increasing the gain level of the gain stage to the second level, in response to the amplified signal being higher than a predetermined threshold, lower the gain level of the gain stage from the second level;
after the selected duration, set the gain level at the gain stage to a lower level that is lower than the second level to cause the gain stage to generate the amplified signal with the lower level; and
processing circuitry, coupled to the capacitive measurement circuitry, and configured to process user inputs corresponding to the amplified signal communicated from the capacitive measurement circuitry.