US 12,322,203 B2
Biometric skin contact sensor and methods of operating a biometric skin contact sensor
Henricus Derckx, St Asaph (GB); Michael Cowin, St Asaph (GB); Wilhelmus Van Lier, St Asaph (GB); and Toru Sakai, St Asaph (GB)
Assigned to TOUCH BIOMETRIX LIMITED, St Asaph (GB)
Appl. No. 18/024,861
Filed by TOUCH BIOMETRIX LIMITED, St Asaph (GB)
PCT Filed Sep. 7, 2021, PCT No. PCT/GB2021/052299
§ 371(c)(1), (2) Date Mar. 6, 2023,
PCT Pub. No. WO2022/049399, PCT Pub. Date Mar. 10, 2022.
Claims priority of application No. 2014008 (GB), filed on Sep. 7, 2020; and application No. 2015383 (GB), filed on Sep. 29, 2020.
Prior Publication US 2023/0326230 A1, Oct. 12, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. G06V 40/13 (2022.01)
CPC G06V 40/1306 (2022.01) 20 Claims
OG exemplary drawing
 
1. A capacitive biometric skin contact sensor configured to resolve the contours of skin in contact with the sensor, wherein the sensor comprises:
an array of sensor pixels, wherein each sensor pixel comprises a thin film transistor and a capacitive sensing electrode connected to the thin film transistor;
a plurality of gate drive channels, wherein each gate drive channel is arranged to provide a gate drive signal to one or more of the sensor pixels;
a plurality of read-out channels, wherein each read-out channel is arranged to receive a read-out current from one or more of the sensor pixels, each read-out current being indicative of a proximity to a respective capacitive sensing electrode of a conductive object to be sensed;
a current multiplexer connected to a first plurality of the read-out channels to receive read-out currents therefrom, wherein the current multiplexer is configured to select one or more read-out currents from said first plurality of read-out channels; and
analog to digital converter comprising a dual slope integrator arranged to receive, as its input, either an output current based on the one or more read-out currents selected by the current multiplexer or a reference voltage;
wherein the biometric sensor is configured to:
apply the output current as the input to the dual slope integrator for a charging time period to charge a capacitor of the dual slope integrator;
apply the reference voltage as the input to the dual slope integrator for a discharging time period, wherein the discharging time period comprises the amount of time it takes for the capacitor to discharge; and
determine the proximity to the one or more respective capacitive sensing electrodes of the conductive body based on an indication of the discharging time period;
wherein the sensor is configured to control: (i) a sensor resolution by controlling the number of read-out currents selected by the multiplexer, and (ii) a sensor sensitivity by controlling the charging time period for the dual slope integrator.