US 11,719,671 B2
Methods of distinguishing among touch events
Sina Akhbari, San Jose, CA (US); Zhongxuan Tu, Shanghai (CN); Michael Chen, Sunnyvale, CA (US); and Hao-Yen Tang, San Jose, CA (US)
Assigned to UltraSense Systems, Inc., San Jose, CA (US)
Filed by UltraSense Systems, Inc., San Jose, CA (US)
Filed on Oct. 19, 2021, as Appl. No. 17/504,758.
Claims priority of provisional application 63/105,842, filed on Oct. 26, 2020.
Prior Publication US 2022/0128516 A1, Apr. 28, 2022
Int. Cl. G01N 29/24 (2006.01); G01L 1/16 (2006.01); G01L 1/14 (2006.01); G01N 29/44 (2006.01)
CPC G01N 29/2437 (2013.01) [G01L 1/142 (2013.01); G01L 1/16 (2013.01); G01N 29/44 (2013.01); G01N 2291/102 (2013.01)] 61 Claims
OG exemplary drawing
 
1. A method of distinguishing between a first-type touch event and a second-type touch event at a sense region, comprising the steps of:
(A) configuring a force-measuring and touch-sensing system at the sense region, the system comprising:
at least one piezoelectric force-measuring element (PFE), each PFE comprising a piezoelectric capacitor; and
at least one piezoelectric ultrasonic transducer (PUT), each PUT comprising a piezoelectric capacitor;
wherein each PUT can be configured as a transmitter (PUT transmitter) and/or a receiver (PUT receiver) and the at least one PUT includes at least one PUT transmitter and at least one PUT receiver;
(B) transmitting, by each PUT transmitter, ultrasound signals of a first frequency F1, in longitudinal mode(s) propagating along a direction approximately normal to a plane of the respective piezoelectric capacitor towards the sense region;
(C) reading, by a signal processing circuitry, voltage signals from the PUT receiver(s) (PUT voltage signals) generated in response to ultrasound signals of the first frequency F1 arriving at the PUT receivers from the sense region;
(D) reading, by the signal processing circuitry, voltage signals from the PFE(s) (PFE voltage signals) generated in response to a low-frequency mechanical deformation of the respective piezoelectric capacitor;
(E) processing the PUT voltage signals to obtain PUT digital data;
(F) processing the PFE voltage signals to obtain PFE digital data;
(G) determining that an event is a first-type touch event if (1a) the PUT digital data decrease by at least a minimum decrease percentage of a predetermined dynamic range in a moving time window of a predetermined duration, and (2a) a magnitude of the PFE digital data is greater than a PFE noise threshold value;
(H) determining that the event is a second-type touch event if (1a) the PUT digital data decrease by at least the minimum decrease percentage of the predetermined dynamic range in the moving time window of the predetermined duration, and (2b) the magnitude of the PFE digital data is not greater than the PFE noise threshold value; and
(I) determining that the event is of neither the first-type touch event nor the second-type touch event if (1b) the PUT digital data do not decrease by at least the minimum decrease percentage of the predetermined dynamic range in the moving time window of the predetermined duration;
wherein the first-type touch event comprises a first object contacting the sense region and the second-type touch event comprises a second object contacting the sense region;
wherein the steps of (B) transmitting ultrasound signals, (C) reading of voltage signals from the PUT receiver(s), and (D) reading of voltage signals from the PFE(s) are carried out concurrently; and
wherein the minimum decrease percentage is at least 1% and the predetermined duration is in a range of 100 ms to 300 ms.