Hybrid optical and capacitive sensor

Abstract

A hybrid capacitive and optical fingerprint sensor system includes: capacitive sensor electrodes; an optical image sensor having a plurality of image sensor pixels; light conditioning elements, configured to condition light from a sensing region of the hybrid capacitive and optical fingerprint sensor for detection by the optical image sensor; and a processing system having one or more controllers, configured to operate the capacitive sensor electrodes in a low-power mode of operation for the hybrid capacitive and optical fingerprint sensor, and to operate the optical image sensor to acquire an image from the sensing region of the hybrid capacitive and optical fingerprint sensor.

1 . A fingerprint sensor, comprising:
 an optical image sensor having a plurality of image sensor pixels;   capacitive sensor electrodes arranged outside of an active sensing area of the optical image sensor; and   one or more controllers configured to operate the capacitive sensor electrodes to detect a presence of a finger, and to operate the optical image sensor in a wake-on-finger mode in which the optical image sensor remain off, while the capacitive sensor electrodes are operated to detect the presence of a finger.   
     
     
         2 . The fingerprint sensor according to  claim 1 , wherein the one or more controllers are configured to activate the optical image sensor when a presence of a finger is detected by the capacitive sensor electrodes. 
     
     
         3 . The fingerprint sensor according to  claim 1 , wherein the capacitive sensor electrodes are arranged adjacent to the optical image sensor. 
     
     
         4 . The fingerprint sensor according to  claim 1 , wherein the capacitive sensor electrodes are arranged below a cover glass of a display panel. 
     
     
         5 . The fingerprint sensor according to  claim 1 , wherein the capacitive sensor electrodes are arranged below a display panel. 
     
     
         6 . The fingerprint sensor according to  claim 1 , wherein the capacitive sensor electrodes are made of a transparent material. 
     
     
         7 . The fingerprint sensor according to  claim 1 , further comprising a capacitive touch sensor configured to detect position information of an input object within a sensing region of the optical fingerprint sensor. 
     
     
         8 . The fingerprint sensor according to  claim 7 , wherein the capacitive sensor electrodes are part of the capacitive touch sensor. 
     
     
         9 . The fingerprint sensor according to  claim 7 , wherein the capacitive touch sensor is configured to switch from a low-power mode to a higher power mode if a presence of a finger is detected. 
     
     
         10 . The fingerprint sensor according to  claim 8 , wherein the one or more controllers are further configured to operate the capacitive touch sensor to determine coverage of a sensing region of the fingerprint sensor by a fingerprint, to adjust settings for the optical image sensor based on the determined coverage of the sensing region by the fingerprint, and to operate the optical image sensor to acquire an image from the sensing region of the fingerprint sensor using the adjusted settings. 
     
     
         11 . The fingerprint sensor according to  claim 1 , wherein the capacitive sensor electrodes are configured to detect presence, position, and/or movement of the fingerprint. 
     
     
         12 . The fingerprint sensor according to  claim 1 , wherein the capacitive sensor electrodes are interleaved among the plurality of image sensor pixels but are disposed outside of respective optical paths corresponding to the plurality of image sensor pixels. 
     
     
         13 . The fingerprint sensor according to  claim 1 , wherein the capacitive sensor electrodes are configured to determine capacitive properties of an input on the sensing region; and wherein the one or more controllers are configured to determine whether the input is a real biometric input based on capacitive properties of the input. 
     
     
         14 . The fingerprint sensor according to  claim 1 , further comprising a finger illumination light source, wherein the one or more controllers are configured to activate the finger illumination light source when a presence of a finger is detected by the capacitive sensor electrodes. 
     
     
         15 . The fingerprint sensor according to  claim 14 , wherein the finger illumination light source is one or more light emitting diodes (LEDs). 
     
     
         16 . The fingerprint sensor according to  claim 14 , further comprising a light guiding structure configured to direct light from the finger illumination light source to a sensing region of the optical image sensor. 
     
     
         17 . The fingerprint sensor according to  claim 1 , further comprising a display, wherein the one or more controllers are configured to activate active the display to illuminate a finger when a presence of a finger is detected by the capacitive sensor electrodes. 
     
     
         18 . Method for operating a fingerprint sensor comprising an optical image sensor having a plurality of image sensor pixels and capacitive sensor electrodes arranged outside of an active sensing area of the optical image sensor, the method comprising:
 by one or more controllers, operating the capacitive sensor electrodes to detect a presence of a finger;   operating the optical image sensor in a wake-on-finger mode in which the optical image sensor remain off; and   operating the capacitive sensor electrodes to look for the presence of a finger.   
     
     
         19 . The method according to  claim 18 , further comprising, if a presence of a finger is detected by the capacitive sensor electrodes, activating the optical image sensor. 
     
     
         20 . The method according to  claim 18 , further comprising, if a presence of a finger is detected by the capacitive sensor electrodes, activating a finger illumination light source.