BR112019007362B1 - HYBRID CAPACITIVE AND ULTRASONIC DETECTION - Google Patents

Abstract

Systems, methods and apparatus for configuring a fingerprint sensor to operate in a capacitive sensing mode and an ultrasonic sensing mode. A fingerprint sensor can be configured to operate in a capacitive sensing mode by driving a sensing electrode using a controller. In some implementations, an object positioned at or near the sensing electrode may be detected using the fingerprint sensor in capacitive sensing mode, and the controller may actuate fingerprint sensor electrodes differently to configure the fingerprint sensor. to operate in an ultrasonic detection mode. In some implementations, an application processor may be instructed to authenticate a fingerprint of the object from image data obtained when the fingerprint sensor is operating in ultrasonic detection mode. In some implementations, a display of a mobile device containing the fingerprint sensor may be unlocked, or the mobile device may be awakened when the fingerprint is authenticated.

Description

PRIORITY DATA

[0001] This disclosure claims priority to United States Patent Application No. 15/633,164 by D'Souza, et al., filed on June 26, 2017 and titled HYBRID CAPACITIVE AND ULTRASONIC SENSING (Attorney's Dossier No. QUALP447US /163494), and to United States Provisional Patent Application No. 62/407,386 by D'Souza, et al., filed on October 12, 2016 and titled HYBRID CAPACITIVE AND ULTRASONIC SENSING (Attorney's Dossier No. QUALP447PUS/163494P1) , both incorporated herein in full by reference and for all purposes.

TECHNICAL FIELD

[0002] This disclosure refers to the activation of an electronic device based on capacitive and ultrasonic detection.

DESCRIPTION OF RELATED TECHNOLOGY

[0003] In an ultrasonic sensor system, an ultrasonic transmitter can be used to send an ultrasonic wave through a medium, or ultrasonic transmission means, and towards an object to be detected. The transmitter may be operatively coupled with an ultrasonic sensor configured to detect portions of the ultrasonic wave that are reflected from the object. Ultrasonic fingerprint detection device, an ultrasonic pulse can be produced by starting and stopping the transmitter during a very short time interval. At each material interface encountered by the ultrasonic pulse, a portion of the ultrasonic pulse is reflected.

[0004] For example, in the context of an ultrasonic fingerprint imaging means, the ultrasonic wave can travel through a plate on which a person's finger can be placed to obtain a fingerprint image. After passing through the plate, some parts of the ultrasonic wave encounter the skin that is in contact with the plate, e.g. fingerprint ridges, while other parts of the ultrasonic wave encounter air, e.g. valleys between adjacent ridges of a fingerprint, and can be reflected with different intensities back to the ultrasonic sensor. The reflected signals associated with the finger can be processed and converted into a digital value that represents the signal strength of the reflected signal. When multiples of such reflected signals are collected over a distributed area, the digital values of such signals can be used to produce a graphical display of the signal intensity over the distributed area, for example, converting the digital values to an image, thereby producing an image of the fingerprint. Thus, an ultrasonic detection system can be used as a digital imager or other type of biometric scanner. In some implementations, the detected signal intensity can be mapped onto a contour map of the finger that is representative of the depth of detail of the ridge structure.

[0005] Inadvertent activation of a mobile device due to fingerless objects in contact with or near the mobile device can lead to unwanted battery drain, reduced battery life, and sometimes an annoying placement of phone calls or initiation other functions not intended by an authorized user. In other situations, activation of the mobile device may be prevented in difficult environments, such as exposure to freezing, dew point, rain, fog, swimming pools, spas, bathtubs, showers, or complete immersion of the mobile device in water. Wet, sweet or partially moist fingers with local water droplets may also prevent the device from waking up.

SUMMARY

[0006] The examples of systems, methods, computer-readable media, and devices of this disclosure each have several innovative aspects, none of which are exclusively responsible for the desirable attributes described herein.

[0007] In some aspects, a system includes a fingerprint sensor having one or more sensing electrodes and a controller. The controller may be configured to provide one or more first drive signals to the one or more sensing electrodes to configure the fingerprint sensor in a capacitive sensing mode, and provide one or more second drive signals to the one or more electrodes. detection mode to configure the fingerprint sensor in an ultrasonic detection mode. The one or more second trigger signals may be different from the one or more first trigger signals.

[0008] In some implementations, the controller includes an amplifier configured to provide one or more second drive signals in the ultrasonic detection mode. The amplifier may be configured to be in a high impedance state in capacitive sensing mode, wherein such impedance state indicates operation of the amplifier with an output impedance greater than the output impedance of the amplifier in ultrasonic sensing mode. In some implementations, the controller is further configured to configure the fingerprint sensor to operate in ultrasonic sensing mode based on the fingerprint sensor detecting a touch in capacitive sensing mode. In some implementations, a mobile device housing the fingerprint sensor is configured to wake up from a standby mode responsive to the fingerprint sensor that detects touch in capacitive sensing mode and ultrasonic sensing mode. In some implementations, a mobile device housing the fingerprint sensor is configured to wake from a sleep mode responsive to the fingerprint sensor detecting touch in capacitive sensing mode and an authorized fingerprint in ultrasonic sensing mode. In some implementations, a mobile device housing the fingerprint sensor is configured to allow a user further access to device data, programs, or capabilities responsive to the fingerprint sensor that detects touch in capacitive sensing mode and a fingerprint. authorized in ultrasonic detection mode.

[0009] In some implementations, the controller is further configured to provide, to an application processor configured to perform fingerprint authentication, an interrupt signal representing that a finger corresponding to the touch is detected by the fingerprint sensor in fingerprint mode. capacitive detection. In some implementations, the controller is further configured to determine a touch detection threshold, which may be based at least in part on a contact area of a finger in contact with the fingerprint sensor. The touch detection threshold can be adjusted during a fingerprint authentication process.

[0010] In some implementations, the controller is additionally configured to report a finger lift event while operating in either the capacitance sensing mode or the ultrasonic sensing mode. In some implementations, the controller is additionally configured to determine a temperature corresponding to the fingerprint sensor. Touch sensing in capacitive sensing mode can be based, at least in part, on temperature.

[0011] In some implementations, the controller includes a set of circuitry for generating a first buffered drive signal provided to the at least one detection electrode of the fingerprint sensor when the fingerprint sensor is in capacitive detection mode. . In some implementations, the fingerprint sensor includes one or more piezoelectric micromachined ultrasonic transducers (PMUTs), one or more micromachined ultrasonic transducers (CMUTs), one or more layers of polyvinyl fluoride (PVDF), or one or more layers of polyvinylidene-trifluoroethylene fluoride (PVDF-TrFE).

[0012] In some implementations, the fingerprint sensor detection electrodes include a first electrode and a second electrode. The first electrode, such as a touch screen electrode, is electrically coupled to the controller to provide a first signal for operating the fingerprint sensor in capacitive sensing mode. The second electrode is electrically coupled to the controller to provide a second signal to operate the fingerprint sensor in ultrasonic fingerprint detection mode. The first electrode and the second electrode may be positioned under a glass cover of a mobile device, around the perimeter of a mobile device, under a back cover of a mobile device, or under a screen of a display device, for example. example. In some implementations, the display of the display device indicates a position of the fingerprint sensor in accordance with the present invention a finger touch is detected in the capacitive sensing mode or in the ultrasonic sensing mode. In some implementations, the display device display indicates a recommendation of a position in which a user can place their finger. The first electrode and/or the second electrode may be configured to detect a finger gesture.

[0013] In some implementations, the controller may configure the one or more sensing electrodes in ultrasonic sensing mode upon indicating a change in motion or a change in orientation from an on-device accelerometer or an on-device gyroscope, wherein “ on device” denotes that the accelerometer or gyroscope is housed within the same enclosing device as the controller is, such as where a controller and an accelerometer are housed within the same telephone handset in some implementations, the controller may be configured to adjust a finger detection rate in capacitive detection mode or in ultrasonic detection mode when indicating a change in movement or a change in orientation of an on-device accelerometer or an on-device gyroscope. In some implementations, the controller may be configured to adjust a touch detection threshold upon indicating a change in motion or a change in orientation of an on-device accelerometer or an on-device gyroscope. In some implementations, the controller may be configured to detect an acoustically generated piezoelectric signal in capacitive sensing mode. For example, the acoustically generated piezoelectric signal may originate from a shunt, a friction, or an acoustic emission from a finger.

[0014] In some aspects, a method for configuring a fingerprint sensor includes configuring, by a controller, the fingerprint sensor to operate in a capacitive sensing mode; determining that an object has touched a detection electrode using the fingerprint sensor in capacitive detection mode; configuring, by the controller, the fingerprint sensor to operate in an ultrasonic detection mode; determining that the object that touched the detection electrode is a finger using the fingerprint sensor in ultrasonic detection mode; and instructing an application processor to wake up and authenticate a finger fingerprint.

[0015] In some implementations, configuring the fingerprint sensor to operate in ultrasonic detection mode includes driving an amplifier to provide a drive signal to signal an electrode of the fingerprint sensor and configuring the amplifier to operate in a high impedance state in capacitive sensing mode. Instructing the application processor to authenticate the fingerprint may include asserting an interrupt signal representing that the object is determined to be a finger using the fingerprint sensor in ultrasonic detection mode. In some implementations, the method may further include returning to a home screen or network unlocking a display of a mobile device when the finger print has been authenticated.

[0016] In some implementations, the method may include causing additional features of the systems described above to be realized.

[0017] In some aspects, a non-transitory computer-readable medium stores instructions executable by one or more processors of a controller to cause a method to be executed for configuring a fingerprint sensor. The instructions may be configured so that the method includes configuring the fingerprint sensor to operate in a capacitive sensing mode; determining that an object has touched a detection electrode using the fingerprint sensor in capacitive detection mode; configure the fingerprint sensor to work in an ultrasonic detection mode; determining that the object that touched the detection electrode is a finger using the fingerprint sensor in ultrasonic detection mode; and instructing an application processor to authenticate a finger print. In some implementations, the method may further include returning to a home screen or shutting down a mobile device when the finger print has been authenticated.

[0018] In some implementations, instructions may be configured to cause additional aspects of the systems and/or methods described above to be performed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Details of one or more implementations of the subject matter described in this specification are set out in the attached drawings and in the description below. Other features, aspects and advantages will become apparent from the description, drawings and claims. Note that the relative dimensions of the following figures may not be drawn to scale.

[0020] Similar reference numbers and designations in the various drawings indicate similar elements.

[0021] Figure 1 shows a front view of a diagrammatic representation of an exemplary mobile device that includes an ultrasonic detection system according to some implementations.

[0022] Figure 2A shows a block diagram representation of components of an exemplary ultrasonic detection system according to some implementations.

[0023] Figure 2B shows a block diagram representation of components of an exemplary mobile device that includes the ultrasonic detection system of Figure 2A.

[0024] Figure 3a shows a cross-sectional projection view of a diagrammatic representation of a portion of an exemplary ultrasonic detection system according to some implementations.

[0025] Figure 3B shows an enlarged cross-sectional side view of the exemplary ultrasonic detection system of Figure 3a according to some implementations.

[0026] Figure 4A shows an exploded projection view of example components of the exemplary ultrasonic detection system of Figures 3A and 3B according to some implementations.

[0027] Figure 4B shows an exploded projection view of example components of an ultrasonic transceiver assembly in an ultrasonic sensor system of Figures 3A and 3B according to some implementations.

[0028] Figure 5 shows an example of using a fingerprint sensor in capacitive detection and ultrasonic detection modes to “wake up” an electronic device.

[0029] Figure 6 shows an example of a flowchart for using the fingerprint sensor in capacitive detection and ultrasonic detection modes to wake up the electronic device.

[0030] Figure 7A shows an example of a circuit schematic of a controller circuit configuring a fingerprint sensor to operate in a capacitive detection mode.

[0031] Figure 7B shows an example of a circuit schematic of a controller circuit configuring a fingerprint sensor to operate in an ultrasonic detection mode.

[0032] Figure 8 shows an example of a circuit diagram of a controller circuit for configuring a fingerprint sensor to operate in capacitive or ultrasonic detection modes.

[0033] Figure 9 shows another example of a circuit diagram of a controller circuit for configuring a fingerprint sensor to operate in capacitive or ultrasonic detection modes.

[0034] Figure 10 shows another example of a circuit diagram of a controller circuit for configuring a fingerprint sensor to operate in capacitive or ultrasonic detection modes.

[0035] Figure 11 shows an example of a high-level block diagram of a controller circuit, fingerprint sensor and an application processor.

[0036] Figure 12 shows another example of a high-level block diagram of a controller circuit, fingerprint sensor and application processor.

[0037] Figure 13 shows an example of adjusting a capacitance determined using the temperature-based fingerprint sensor.

[0038] Figure 14 shows an example of a flowchart for adjusting the capacitance determined using a fingerprint sensor.

[0039] Figure 15A shows an example of a flowchart for a method of using a capacitive detection mode and an ultrasonic detection mode to detect the presence of an object using a fingerprint sensor.

[0040] Figure 15B shows an example of a flowchart for a method of using a capacitive detection mode to initially detect the presence of an object and an ultrasonic detection mode to detect the continued presence of the object and to detect when the object was lifted using a fingerprint sensor.

[0041] Figure 15C shows an example of a flowchart for a method of using a capacitive detection mode to initially detect the presence of an object, in both the ultrasonic detection mode and the capacitive detection mode to detect the presence continuous movement of the object and to detect when the object has been lifted using a fingerprint sensor.

[0042] Figure 16A shows an example of using a capacitive sensing mode and an ultrasonic sensing mode with a fingerprint sensor and one or more associated sensing electrodes to wake up an electronic device.

[0043] Figure 16B shows another example of using a capacitive sensing mode and an ultrasonic sensing mode with a fingerprint sensor and one or more associated sensing electrodes to wake up an electronic device.

[0044] Figure 17 shows a side view of a configuration with a fingerprint sensor and one or more detection electrodes positioned under a cover glass of a display device.

[0045] Figure 18 shows an example of using a capacitive sensing mode and an ultrasonic sensing mode with a fingerprint sensor positioned behind a screen of an electronic device to wake up the electronic device.

[0046] Figure 19 shows a side view of a configuration with a fingerprint sensor positioned behind a screen of a mobile device.

[0047] Figure 20 shows an example of a flowchart for a method for guiding a user of an LCD or OLED display device to position a finger above an under-LCD or under-OLED fingerprint sensor.

[0048] Figure 21 shows an example of using a capacitive detection mode and an ultrasonic detection mode with a fingerprint sensor and one or more associated detection electrodes, positioned behind a screen of an electronic device to awaken the electronic device.

[0049] Figure 22 shows a side view of a configuration with a fingerprint sensor and one or more associated detection electrodes positioned behind a screen of a mobile device.

[0050] Figure 23 a shows an example of using a capacitive detection mode and an ultrasonic detection mode with a fingerprint sensor and one or more associated detection electrodes positioned behind a back cover of an electronic device .

[0051] Figure 23B shows an example of using a capacitive detection mode and an ultrasonic detection mode with a fingerprint sensor and one or more associated detection electrodes positioned behind a back cover of an electronic device to detect finger movements.

DETAILED DESCRIPTION

[0052] The following description is directed to certain implementations for the purpose of describing the innovative aspects of this description. However, one skilled in the art will readily recognize that the teachings herein can be applied in a multitude of different ways. The described implementations may be implemented in any device, apparatus or system that includes a biometric system as described herein for ultrasonic detection. Furthermore, it is contemplated that the described implementations may be included in or associated with a variety of electronic devices such as, but not limited to: mobile phones, multimedia Internet-enabled cell phones, mobile television receivers, wireless devices, smart phones , smart cards, clothing devices such as bracelets, straps, wrist straps, rings, headbands and patches, etc. Bluetooth® devices, personal data assistants (PDAs), wireless e-mail receivers, portable or portable computers, netbooks, banners, smart books, tablets, printers, copiers, scanners, facsimile devices, global positioning system ( GPS) receivers/navigators, cameras, digital media players (such as MP3 players), video cameras, game consoles, wristwatches, clocks, calculators, television monitors, flat panel displays, reading devices electronics (e.g., e-readers), mobile health devices, computer monitors, automobile displays (including odometer and speedometer displays, etc.), cabin controls and/or displays, camera view screens (such as the display of a rear view camera in a vehicle), electronic photographs, electronic posters or signs, projectors, architectural structures, microwaves, refrigerators, stereo systems, cassette recorders or players, DVD players, CD players, VCRs , radios, portable memory chips, washers, dryers, washer/dryers Automatic teller machines (ATMs), parking meters, packaging (such as in electromechanical systems (EMS) applications including microelectromechanical systems (MEMS) applications, as well as applications non-EMS), aesthetic structures (such as displaying images on a piece of jewelry or clothing), and a variety of EMS devices. The teachings herein may also be used in applications such as, but not limited to, electronic switching devices, radio frequency filters, sensors, accelerometers, gyroscopes, motion detection devices, magnetometers, inertial components for consumer electronics, parts of electronic products. devices, varactors, liquid crystal devices, electrophoretic devices, drive schemes, manufacturing processes and electronic test equipment. Thus, the teachings are not intended to be limited to the implementations described in the Figures alone, but rather have broad applicability as will be readily apparent to one skilled in the art.

[0053] Electronic devices such as smart phones, tablets and useful devices may be in a low-power operating mode in which the display screen and application processor may be turned off or in a low-power standby mode. In some configurations, the device can be “woken up” from low-power or off mode by pressing a dedicated power button or by detecting a finger (that is, any of the fingers on the hand, including the thumb, the pad of the thumb near the basal joint of the thumb, and the palm of the hand) over a biometric button associated with the mobile device or by touching a touch screen with a finger. Fingers can be detected using capacitive sensing, which includes measuring a change in capacitance in a circuit to detect a touch (e.g., a finger touching or swatting the touchscreen). However, objects other than a finger (e.g., a metal table top, objects in a purse or purse, a user's cheek, etc.) touching the touch screen can also result in a change in capacitance. These other objects may create a false determination that a finger has touched the touch screen, resulting in the application processor and touch screen display to turn on when they should remain off. Additionally, one finger touching the touchscreen must be the owner's. That is, the application processor and touchscreen display must turn on (e.g., unlock the device) when an owner's finger is detected rather than other objects or other people's fingers. Spinning of the application processor and touch screen display may result in high current consumption. As a result, false positives can drain the device's battery.

[0054] In some implementations, a two-step capacitance sensing and ultrasonic sensing method may be performed to “wake up” an application processor which may include turning on a display or other parts of a mobile device, entering a mode of higher power consumption, or entering a mode that provides greater access to an authenticated user's software, data, related information, or device capabilities. For example, a fingerprint sensor may be configured to operate in a capacitive sensing mode to detect a touch and operate in an ultrasonic sensing mode to detect whether the touch is coming from a finger. In some implementations, the same fingerprint sensor electrode (or electrodes) can be used in both capacitive sensing and ultrasonic sensing modes. In some implementations, one or more sensing electrodes of or associated with the fingerprint sensor may be configured to operate in capacitive sensing mode and one or more other sensing electrodes may be configured to operate in ultrasonic sensing mode. In some implementations, a complete set of piezoelectric sensor pixels or a smaller subset of pixel elements in the fingerprint sensor may be used when operating in ultrasonic detection mode. Accordingly, the fingerprint sensor may first be configured to operate in capacitive sensing mode and if a touch is detected, then the fingerprint sensor may be configured to operate in ultrasonic detection mode to determine whether the touch is coming from a finger. A controller may include a controller circuit and one or more controller circuits for providing different sets of one or more drive signals to the electrode (or electrodes) such that the same fingerprint sensor can switch operation between the two modes. If the touch is coming from a finger, the controller circuit may provide an interrupt signal as an indicator or trigger indicating that the application processor should wake up, authenticate a fingerprint based on the finger detected during the ultrasonic detection mode, and if authenticated, turn on the touchscreen display screen, and unlock the device so that it is in a user-readable mode. In some implementations where the mobile device's application processor is already awake and the mobile device is unlocked, the interrupt signal generated by the two-step capacitive and ultrasonic sensing method may cause the mobile device to return to the home screen and prepare additional user input if the mobile device is not already in a home screen mode, or may cause the mobile device to allow greater access to software, data, information related to an authenticated user, or device capabilities.

[0055] Two-step capacitance detection and ultrasonic detection can reduce the number of false positives and therefore reduce the current consumption of the device and increase the battery life of the device. Additionally, capacitive sensing often uses a lower current than ultrasonic sensing. Therefore, first using capacitive sensing before proceeding with ultrasonic sensing can provide additional savings in battery life and prevent unintentional or inadvertent use of the mobile device.

[0056] Figure 1 shows a diagrammatic representation of an exemplary mobile device 100 that includes an ultrasonic detection system according to some implementations. The mobile device 100 may be representative of, for example, various portable computing devices, cell phones, smart phones, smart watches, multimedia devices, personal gaming devices, desktop computers, and laptop computers, among other types of portable computing devices. . However, several implementations described here are not limited in application to portable computing devices. In fact, several techniques and principles described here can be applied to traditionally non-portable devices and systems, such as computer monitors, television screens, kiosks, vehicle navigation devices and audio systems, among other applications. Additionally, various implementations described here are not limited in application to devices that include displays.

[0057] The mobile device 100 generally includes an enclosure (also referred to as a "housing" or "case") 102 within which various circuits, sensors, and other electrical components reside. In the illustrated exemplary implementation, the mobile device 100 also includes a touch screen display (also referred to herein as a “touch display”) 104. The touch screen display 104 generally includes a display and a touch screen. touch disposed on or otherwise incorporated into or integrated with the display. The screen 104 may generally be representative of any of a variety of suitable display types that employ any of a variety of suitable display technologies. For example, the display 104 may be a digital micro-shutter (DMS) display based on a light-emitting diode (LED) display, an organic LED display (OLED), a liquid crystal display (LCD), a LCD that uses LEDs as backlights, a plasma display, an interferometric modulator (IMOD)-based display, or another type of display suitable for use in conjunction with touch-sensitive user interface (UI) systems.

[0058] The mobile device 100 may include various other devices or components for interacting with or otherwise communicating information to or receiving information from a user. For example, the mobile device 100 may include one or more microphones 106, one or more speakers 108, and, in some cases, one or more at least partially mechanical buttons 110. The mobile device 100 may include various other components that enable features additional devices such as, for example, one or more video or still image cameras 112, one or more wireless network interfaces 114 (e.g., Bluetooth, WiFi, or cellular), and one or more non-wireless interfaces 116 (e.g., , a universal serial bus (USB) interface, or an HDMI interface).

[0059] Mobile device 100 may include an ultrasonic detection system 118 capable of scanning and imaging an object signature, such as a fingerprint, palm print, or handprint. In some implementations, the ultrasonic detection system 118 may function as a touch-sensitive control button. In some implementations, a touch-sensitive control button may be implemented with a pressure-sensitive mechanical or electrical system that is positioned under or without voltage otherwise integrated with the ultrasonic detection system 118. In other words, in some implementations, A region occupied by the ultrasonic detection system 118 may function as both a user input button for controlling the mobile device 100 as well as a fingerprint sensor to enable security features such as user authentication features. In some implementations, the ultrasonic detection system 118 may be positioned under the cover glass of the display or under a portion of the display itself. In some implementations, the ultrasonic detection system 118 may be positioned on a side wall or table on the rear side of the mobile device enclosure 102. The enclosure 102 may house a fingerprint sensor as part of the ultrasonic detection system 118 that is configurable. to operate in a capacitive sensing mode or an ultrasonic sensing mode.

[0060] Figure 2A shows a block diagram representation of components of an exemplary ultrasonic detection system 200, according to some implementations. As shown, the ultrasonic detection system 200 may include a sensor system 202 and a control system 204 electrically coupled to the sensor system 202. The sensor system 202 may be capable of scanning an object and providing usable raw measured image data. to obtain an object signature such as, for example, a fingerprint of a human finger. The control system 204 may be capable of controlling the sensor system 202 and processing the raw measured image data received from the sensor system. In some implementations, the ultrasonic detection system 200 may include an interface system 206 capable of transmitting or receiving data, such as image data, raw or processed measurements, or from various components within or integrated with the ultrasonic detection system 200 or , in some implementations, to or from multiple component devices or other systems external to the ultrasonic detection mode.

[0061] Figure 2B shows a block diagram representation of components of an exemplary mobile device 210 that includes the ultrasonic detection system 200 of Figure 2 a, for example, the mobile device 210 may be a block diagram representation of the mobile device 100, shown and described with reference to Figure 1 above. The sensor system 202 of the ultrasonic detection system 200 of the mobile device 210 may be implemented with an ultrasonic sensor array 212. The control system 204 of the ultrasonic detection system 200 may be implemented with a controller 214 that is electrically coupled to the array. of ultrasonic sensor 212. While controller 214 is shown and described as a single component, in some implementations, controller 214 may collectively refer to two or more more distinct control units or processing units in electrical communication with each other. In some implementations, controller 214 may include one or more of a general purpose single-chip or multi-chip processor, a central processing unit (CPU), a digital signal processor (DSP), an application processor, a circuit application-specific integrated system (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete physical components, or any combination thereof, designed to perform the functions and operations described here.

[0062] The ultrasonic detection system 200 of Figure 2B may include an image processing module 218. In some implementations, the raw measured image data provided by the ultrasonic sensor array 212 may be sent, transmitted, communicated, or otherwise provided to the image processing module 218. The image processing module 218 may include any suitable combination of hardware, firmware and software configured, adapted or otherwise operable to process the image data provided by the ultrasonic sensor array 212. In In some implementations, the image processing module 218 may include signal or image processing circuits or circuit components including, for example, amplifiers (such as instrumentation amplifiers or intermediate storage amplifiers), analog or digital mixers or multipliers, switches , analog to digital converters (ADCs), passive filters or active analog filters, among others. In some implementations, one or more such circuits or circuit components may be integrated within the controller 214, for example, where the controller 214 is implemented as a system-on-chip (SoC) or system-in-package (SIP). In some implementations, one or more such circuits or circuit components may be integrated within a DSP included within or coupled to the controller; in some implementations, the image processing module 218 may be implemented at least partially through software. For example, one or more functions of, or operations performed by, one or more of the circuits or circuit components just described may, instead, be performed by one or more software modules executing, for example, in a unit processor 214 (such as in a general purpose processor or a DSP). In some implementations, the image processing module 218 or portions thereof may be implemented in software and may run on an application processor, such as the processor 220 associated with the mobile device, the application processor may have a dedicated coprocessor and/or or software modules for the secure processing of biometric image data within the application processor (sometimes referred to as the “zone of trust”).

[0063] In some implementations, in addition to the ultrasonic detection system 200, the mobile device 210 may include a separate processor 220, a memory 222, an interface 216, and a power supply 224. In some implementations, the controller 214 of the ultrasonic detection 200 may control the ultrasonic sensor array 212 and the image processing module 218, and the processor 220 of the mobile device 210 may control other components of the mobile device 210. In some implementations, the processor 220 communicates data to the controller 214, including, for example, instructions or commands. In some such implementations, controller 214 may communicate data to processor 220, including, for example, raw or processed image data (also referred to as “image information”). It should also be understood that, in some other implementations, the functionality of controller 214 may be implemented entirely, or at least partially, by processor 220. In some such implementations, a separate controller 214 for the ultrasonic detection system 200 may not be available. required because the functions of the controller 214 can be performed by the processor 220 of the mobile device 210.

[0064] Depending on the implementation, one or both of controller 214 and processor 220 may store data in memory 222. For example, data stored in memory 222 may include raw measured image data, filtered image data, or otherwise processed image data. , estimated image data, or final refined image data. Memory 222 may store processor-executable code or other computer-executable instructions capable of execution by either or both the controller 214 and the processor 220 to perform various operations (or to cause other components such as the ultrasonic sensor array 212, the image processing module 218, or other modules for performing operations), including any of the calculations, computations, estimates or other determinations described herein. It should also be understood that memory 222 may refer collectively to one or more memory devices (or “components”). For example, depending on the implementation, controller 214 may have access to and store data in a different memory device than processor 220. In some implementations, one or more of the memory components may be implemented as a flash memory array based on in NOR or NAND. In some other implementations, one or more of the memory components may be implemented as a different type of non-volatile memory. Additionally, in some implementations, one or more of the memory components may include a volatile memory pool such as, for example, a type of RAM.

[0065] In some implementations, controller 214 or processor 220 may communicate data stored in memory 222 or data 204 received directly from image processing module 218 via an interface 216. For example, such communicated data may include image data or data derived from or otherwise determined from image data. Interface 216 may collectively refer to one or more interfaces of one or more various types. In some implementations, interface 216 may include a memory interface for receiving data from data storage to an external memory such as a removable memory device. Additionally or alternatively, interface 216 may include one or more wireless network interfaces or one or more wired network interfaces that enable the transfer of raw or processed data, as well as the reception of data from an external computing device, system or server.

[0066] The energy source 224 may include one or more of a variety of energy storage devices. For example, the power supply 224 may include a rechargeable battery, such as a nickel-cadmium battery or a lithium ion battery. Additionally or alternatively, the power supply 224 may include one or more supercapacitors. In some implementations, the power supply 224 may be chargeable (or “rechargeable”) using power accessed from, for example, a wall socket (or “outlet”) or a photovoltaic device (or “solar cell” or “ solar cell array”) integrated with the mobile device 210. Additionally or alternatively, the power supply 224 may be wirelessly chargeable. The power supply 224 may include a power management integrated circuit and a power management system.

[0067] As used below, the term “processing unit” refers to any combination of one or more of an ultrasonic system controller (e.g., controller 214), an image processing module (e.g., , the image processing module 218), or a processor separate from a device that includes the ultrasonic system (e.g., the processor 220). In other words, the operations that are described below as being performed by or using a processing unit may be performed by one or more of an ultrasonic system controller, an image processing module, or a separate processor of a device that includes the ultrasonic detection system.

[0068] Figure 3a shows a cross-sectional projection view of a diagrammatic representation of a portion of an exemplary ultrasonic detection system 300 according to some implementations. Figure 3B shows an enlarged cross-sectional side view of the exemplary ultrasonic detection system 300 of Figure 3a according to some implementations. For example, the ultrasonic detection system 300 may implement the ultrasonic detection system 118 described with reference to Figure 11 or the ultrasonic detection system 200 shown and described with reference to Figure 2a and Figure 2B. The ultrasonic detection system 300 may include an ultrasonic transducer 302 that overlies a substrate 304 and that underlies a plate (e.g., “cover plate” or “cover glass”) 306. The ultrasonic transducer 302 may include an ultrasonic transmitter 308 and an ultrasonic receiver 310.

[0069] The ultrasonic transmitter 308 is generally configured to generate and transmit ultrasonic waves toward the plate 306, and in the illustrated implementation, toward a human finger 312 positioned on the top surface of the cylinder 306. In some implementations, the ultrasonic transmitter 308 may more specifically be configured to generate and transmit ultrasonic plane waves toward the plate 306. For example, the piezoelectric material of the ultrasonic transmitter 308 may be configured to convert the electrical signals provided by the ultrasonic detection system controller into a continuous sequence or pulsed ultrasonic plane waves at a sweep frequency. In some implementations, the ultrasonic transmitter 308 includes a layer of piezoelectric material such as, for example, polyvinylidene fluoride (PVDF) or a PVDF copolymer such as PVDF-TrFE. In some implementations, other piezoelectric materials may be used in the ultrasonic transmitter 308 and/or the ultrasonic receiver 310, such as aluminum nitride (AIN) or lead zirconate titanate (PZT). In some implementations, the ultrasonic transmitter 308 and/or the ultrasonic receiver 310 may additionally alternatively include capacitive ultrasonic devices, such as capacitive micromachined ultrasonic transducers (CMUTs) or piezoelectric ultrasonic devices such as piezoelectric micromachined ultrasonic transducers (PMUTs, also referred to as as “piezoelectric micromachined ultrasonic transducers”).

[0070] The ultrasonic receiver 310 is generally configured to detect ultrasonic reflections 314 resulting from the interactions of ultrasonic waves transmitted by the ultrasonic transmitter 308 with ridges 316 and troughs 318 defining the fingerprint of the finger 312 being scanned. In some implementations, the ultrasonic transmitter 308 overlaps the ultrasonic receiver 310, as, for example, illustrated in Figures 3A and 3B. In some implementations, the ultrasonic receiver 310 may overlap the ultrasonic transmitter 308 (as shown in Figure 4a described below). The ultrasonic receiver 310 can be configured to generate and output electrical output signals corresponding to detected ultrasonic reflections. In some implementations, the ultrasonic receiver 310 may include a second piezoelectric layer different from the piezoelectric layer of the ultrasonic transmitter 308. For example, the piezoelectric material of the ultrasonic receiver 310 may be any suitable piezoelectric material such as, for example, a PVDF layer or a PVDF-TrFE copolymer. The piezoelectric layer of the ultrasonic receiver 310 can convert vibrations caused by ultrasonic reflections into electrical output signals. In some implementations, the ultrasonic receiver 310 further includes a thin film transistor (TFT) layer. In some such implementations, the TFT layer may include a sensor pixel circuitry configured to amplify or buffer modulate the output electrical signals generated by the piezoelectric layer of the ultrasonic receiver 310. The output electrical signals provided by the sensor circuitry arrangement sensor pixel may then be provided as raw, measured image data to the processing unit for use in processing the image data, identifying a fingerprint associated with the image data, and in some applications authenticating a user associated with the fingerprint. In some implementations, a single piezoelectric layer may serve as the ultrasonic transmitter 308 and the ultrasonic receiver 310 (as shown in Figure 4B described below). In some implementations, substrate 304 may be a glass, plastic, or silicon substrate upon which electronic circuits may be fabricated. In some implementations, a set of sensor pixel circuitry and interface circuitry associated with the ultrasonic receiver 310 may be configured from CMOS circuitry formed in or on the substrate 304. In some implementations, the substrate 304 may be positioned between the cylinder 306 and the ultrasonic transmitter 308 and/or the ultrasonic receiver 310. In some implementations, the substrate 304 may serve as the board 306. One or more protective layers, acoustic coupling layers, anti-tarnish layers, adhesive layers, decorative layers, conductive layers or other coating layers (not shown) may be included on one or more sides of the substrate 304 and the board 306.

[0071] The plate 306 can be formed from any suitable material that can be acoustically coupled to the ultrasonic transmitter 308. For example, the plate 306 can be formed from one or more glass, plastic, ceramic, sapphire, metal or metal alloy. In some implementations, the plate 306 may be a cover plate such as, for example, a cover glass or a lens glass of an underlying display. In some implementations, the plate 306 may include one or more polymers, such as one or more types of parylene, and may be substantially thinner. In some implementations, the plate 306 may have a thickness in the range of approximately 10 microns (μm) to approximately 1000 μm or more.

[0072] In some implementations, the ultrasonic detection system 300 may further include a focusing layer (not shown). For example, the focusing layer may be positioned above the ultrasonic transmitter 308. The focusing layer may generally include one or more acoustic lenses capable of altering the paths of ultrasonic waves transmitted by the ultrasonic transmitter 308. In some implementations, the lenses may be implemented as cylindrical lenses, spherical lenses or zone lenses. In some implementations, some or all of the lenses may be concave lenses, while in some other implementations some or all of the lenses may be convex lenses, or include a combination of concave and convex lenses.

[0073] In some implementations that include such a focusing layer, the ultrasonic detection system 300 may additionally include an acoustic coincidence layer to ensure appropriate acoustic coupling between the focusing lens and an object, such as a finger, positioned on the plate. 306. For example, the acoustic coincidence layer may include an epoxy doped with particles that alter the density of the acoustic coincidence layer. If the density of the acoustic coincidence layer is changed, then the acoustic impedance will also change in accordance with the change in density if the acoustic velocity remains constant. In alternative implementations, the acoustic coincidence layer may include silicone rubber doped with metal or ceramic powder. In some implementations, sampling strategies for processing output signals may be implemented by MT that take advantage of ultrasonic reflections that are received through a focusing layer lens. For example, an ultrasonic wave that comes from behind a focal point of the lens will travel into the lens and the lens can propagate toward multiple receiving elements in a receiving assembly that satisfies the principle of acoustic reciprocity. Depending on the signal strength coming from the stray field, an adjustment of the number of active receiving elements is possible. In general, the more receiving elements are activated to receive the returned ultrasonic waves, the higher the signal-to-noise (S/N) ratio. In some implementations, one or more acoustic coupling layers may be positioned on one or both sides of the cylinder 306, with or without a focusing layer.

[0074] Figure 4a shows an exploded projection view of example components of the exemplary ultrasonic detection system 300 of Figures 3A and 3B according to some implementations. The ultrasonic transmitter 308 may include a substantially flat piezoelectric transmitter layer 422 capable of functioning as a plane wave generator. Ultrasonic waves can be generated by applying a voltage across the piezoelectric transmitter layer 422 to expand or contract the layer depending on the applied voltage signal, thereby generating a plane wave. In this example, the processing unit (not shown) is capable of causing a transmitter excitation voltage to be applied across the piezoelectric transmitter layer 422 via a first transmitter electrode 424 and a second transmitter electrode 426. The first and second electrodes transmitter layers 424 and 426 may be metallized electrodes, e.g., metallic layers coating opposite sides of the piezoelectric transmitter layer 422. As a result of the piezoelectric effect, the applied transmitter excitation voltage causes changes in the thickness of the piezoelectric transmitter layer 422, and In this way, it generates ultrasonic waves at the frequency of the transmitter's excitation voltage. In some implementations, the first transmitting electrode 424 and/or the second transmitting electrode 426 may be used as a capacitive detector electrode in accordance with the present invention operating in a capacitive sensing mode and as an ultrasonic sensing electrode when operating in a ultrasonic detection mode.

[0075] The ultrasonic waves can travel to a target object such as a finger by passing through the cylinder 306. A portion of the ultrasonic waves, not absorbed or transmitted by the target object, can be reflected back through the cylinder 306 and received by the receiver ultrasonic transmitter 310, which, in the implementation illustrated in Figure 4 a, overlaps the ultrasonic transmitter 308. The ultrasonic receiver 310 may include a set of sensor pixel circuits 432 disposed on a substrate 434 and a piezoelectric receiver layer 436. In some implementations, each sensor pixel circuit 432 may include one or more TFT or silicon-based CMOS transistor elements, electrical interconnect traces, and, in some implementations, one or more additional circuit elements such as diodes, capacitors, and the like. Each sensor pixel circuit 432 may be configured to convert surface charge generated in the piezoelectric receiving layer 436 proximal to the pixel circuit into an electrical signal. Each sensor pixel circuit 432 may include a pixel input electrode 438 that electrically couples the piezoelectric receiver layer 436 to the sensor pixel circuit 432.

[0076] In the illustrated implementation, a receiver bias electrode 440 is disposed on the side of the piezoelectric receiver layer 436 proximate to the plate 306. The receiver bias electrode 440 may be a metallized electrode and may be grounded to the circuitry. of sensor pixel 432. For example, when configured to operate in an ultrasonic detection mode, the polarization electrode of the receiver 440 may serve as a detection electrode. Receiver bias electrode 440 may be driven with a first voltage level corresponding to a block mode during generation of an ultrasonic wave, a second voltage level corresponding to a sample mode when reflected ultrasonic waves are received by the receiver circuits. sensor pixel, and a third voltage level corresponding to a hold mode for retaining the output electrical signals by the pixel circuitry until the output electrical signals are clocked out of the sensor pixel circuitry. Ultrasonic energy that is reflected from the exposed surface (top/top) surface 442 of cylinder 306 can be converted into surface charge by the piezoelectric receiving layer 436. The generated surface charge can be coupled to pixel input electrodes 438 and circuitry of underlying sensor pixel 432. The charge signal may be amplified or temporarily stored by the sensor pixel circuitry 432 and provided to the processing unit. The processing unit may be electrically connected (directly or indirectly) with the first transmitting electrode 424 and the second transmitting electrode 426, as well as with the receiving bias electrode 440 and the sensor pixel circuits 432 on the substrate 434. In some implementations, the processing unit may operate substantially as described above. For example, the processing unit may be capable of processing signals received from sensor pixel circuits 432. In some implementations, the receiver bias electrode 440 may be reconfigured as a sensing electrode when operating in a capacitive sensing mode. and be provided with appropriate trigger signals to detect the touch of a finger or other object.

[0077] Some examples of suitable piezoelectric materials that can be used to form the piezoelectric transmitter layer 422 or the piezoelectric receiver layer 436 include piezoelectric polymers with appropriate acoustic properties, for example, an acoustic impedance between approximately 2.5 MRayls and 5 MRayls. Specific examples of piezoelectric materials that may be employed include ferroelectric polymers such as polyvinylidene fluoride (PVDF) and polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) copolymers. Examples of PVDF copolymers include 60:40 (molar percentage) PVDF-TrFE, 70:30 PVDF-TrFE, 80:20 PVDF-TrFE, and 90:10 PVDR-TrFE. Other examples of piezoelectric materials that can be used include polyvinylidene chloride (PVDC) homopolymers and copolymers, polytetrafluoroethylene (PTFE) homopolymers and copolymers, and diisopropylammonium bromide (DIPAB). In some implementations, other piezoelectric materials may be used in the piezoelectric transmitter layer 422 and/or the piezoelectric receiver layer 436, such as aluminum nitride (AIN) or lead zirconate titanate (PZT).

[0078] The thickness of each of the piezoelectric transmitter layers 422 and the piezoelectric receiving layer 436 is selected so as to be suitable for the generation and reception of ultrasonic waves, respectively. In one example, a piezoelectric transmitter layer of PVDF 422 is approximately 28 μm thick and a receiving layer of PVDF-TrFE 436 is approximately 12 μm thick. Example frequencies of ultrasonic waves can be in the range of about 1 megahertz (MHz) to about 100 MHz, with wavelengths on the order of a millimeter or less.

[0079] As discussed herein, the first transmitting electrode 424, the second transmitting electrode 426, and the receiving bias electrode 440 may be actuated (i.e., provided) such that the ultrasonic detection system 300 may operate in a detection mode. ultrasonic, as discussed above, as well as in a capacitive sensing mode. That is, the same electrodes of the ultrasonic detection system 202 can be used to implement a fingerprint sensor (e.g., using one or more piezoelectric micromachined ultrasonic transducers) to operate in the capacitive detection mode and in the ultrasonic detection mode. As previously discussed, using the same fingerprint sensor to implement capacitive sensing and ultrasonic sensing can enable the reduction of false positives from a finger touching the touchscreen and reduce device battery drain.

[0080] Figure 4B shows an exploded projection view of example components of an ultrasonic transceiver arrangement in an ultrasonic detection system 300 of Figures 3A and 3B according to some implementations. In this example, the ultrasonic detection system 300 includes an ultrasonic transceiver assembly 450 under a plate 306. The ultrasonic transceiver assembly 450 can serve as the ultrasonic sensor array 212 that is shown in Figure 2B and described above. The ultrasonic transceiver assembly 450 may include a substantially flat piezoelectric transceiver layer 456 capable of functioning as a plane wave generator. Ultrasonic waves may be generated by applying a voltage across the piezoelectric transceiver layer 456. The control system 204 may be capable of generating a transceiver excitation voltage that may be applied across the piezoelectric transceiver layer 456 through one or more antennas more underlying pixel input electrodes 438 or one or more overlapping transceiver bias electrodes 460. The generated ultrasonic wave may travel toward a finger or other object to be detected, passing through the plate 306. A portion of the wave not absorbed or transmitted by the object may be reflected so as to pass back through the plate 306 and be received by the ultrasonic transceiver array 50. The ultrasonic transceiver array 50 may serve as an ultrasonic transmitter and an ultrasonic receiver utilizing a single layer of piezoelectric transceiver 456.

[0081] The ultrasonic transceiver assembly 450 may include a set of sensor pixel circuits 432 disposed on a sensor substrate 434. In some implementations, each sensor pixel circuit 432 may include one or more TFT or silicon-based elements , interconnect electrical traces, and, in some implementations, one or more additional circuit elements, such as diodes, capacitors, and the like. Each sensor pixel circuit 432 may include a pixel input electrode 438 that electrically couples the piezoelectric transceiver layer 456 to the sensor pixel circuit 432.

[0082] In the illustrated implementation, the transceiver bias electrode 460 is disposed on one side of the transceiver and the piezoelectric transceiver layer 456 proximate to the plate 306. The transceiver orientation electrode 460 may be used a metallized electrode and may be grounded or grounded. polarized to control which signals can be generated and whose reflected signals can be passed to the sensor pixel circuitry 432. Ultrasonic energy that is reflected from the exposed (top) surface 442 of the cylinder 306 can be converted into charge surface charge by the piezoelectric transceiver layer 456. The generated surface charge may be coupled to the pixel input electrodes 438 and the underlying sensor pixel circuitry 432. The charge signal may be amplified or temporarily amplified or stored by the pixel circuitry sensor 432 and provided with control system 204.

[0083] The control system 204 may be electrically connected (directly or indirectly) to the transceiver bias electrode 460 and the sensor pixel circuits 432 on the sensor substrate 434. In some implementations, the control system 204 may operate substantially as described above. For example, the control system 204 may be capable of processing signal amplified or buffered electrical output signals received from the sensor pixel circuits 432 .

[0084] The control system 204 may be capable of controlling the ultrasonic transceiver assembly 450 to obtain ultrasonic image data, which may include digital image data. According to some implementations, the control system 204 may be capable of providing functionality such as that described herein, for example, as described herein with reference to Figures 1-3B and Figures 5-20.

[0085] In other examples of an ultrasonic sensor system with an array of ultrasonic transceivers, a rear side of the sensing substrate 434 may be attached directly or indirectly to an overlying plate 306. In operation, ultrasonic waves generated by the piezoelectric transceiver layer 456 may travel through the sensor substrate 434 and the plate 306, reflect the surface 442 of the plate 306, and travel back through the cylinder 306 and the sensor substrate 434 before being detected by the sensor pixel circuitry 432 on or in the substrate sensor 434.

[0086] In greater detail, Figure 5 shows an example of using a fingerprint sensor in capacitive detection and ultrasonic detection modes to “wake up” an electronic device. In Figure 5, electronic device 505 (e.g., mobile device 210) includes controller circuit 520 (e.g., controller 214 in Figure 2B) that can switch sensor 525 (e.g., at least one of the ultrasonic sensors of the ultrasonic sensor 212 of the ultrasonic detection system 202 in Figure 2B) to operate between a capacitive detection mode and an ultrasonic detection mode. Figure 6 shows an example of a flowchart for using the fingerprint sensor in capacitive sensing and ultrasonic sensing modes to wake up the electronic device. In Figure 6, in block 605, an electronic device may be in a “locked” state in which an application processor and display of the electronic device are turned off or are in a low-power standby mode. For example, in Figure 5, at time 550, the electronic device 505 is in the locked state. This results in the display 510 (i.e., a touchscreen display of the electronic device 505) being turned off (i.e., no visual image content is being displayed) and the application processor 530 (e.g., the processor 220 in the Figure 2B) can be turned off or in a relatively low power “sleep” mode.

[0087] Next, in block 610, an object can be detected using capacitive detection. For example, in Figure 5, at time 550, finger 515 is placed above sensor 525 that is part of an ultrasonic authentication button (e.g., “start button”) of electronic device 505. In some implementations, the sensor 525 may be part of an electromechanical button that can validate or otherwise authenticate a user and is used inserted through a cutout region in the cover glass of the display 510. In some implementations (such as illustrated in Figure 5), the sensor 525 can be positioned behind the cover glass of the display 510 without requiring cutouts in the cover glass. In the simplified example of Figure 5, controller circuit 520 also has configured sensor 525 to operate in a capacitive sensing mode, as represented with the switch state in electronic device 505. This results in sensor 525 being used to implement a capacitive sensing system. , and therefore, an object positioned near or on the display 510, sensor 525, or other detection electrode formed on or under the cover glass of the electronic device 505 can be detected. For example, the capacitance of the object in the button or display device can be modeled as part of a capacitive voltage divider with one of the sensor electrodes 525 and a voltage corresponding to the capacitance can be “read” by a corresponding sensor circuit, as discussed previously. In some implementations, one or more electrodes of a touch screen such as a projected capacitive touch (PCT) touch screen may serve as a sensing electrode when operating in capacitive sensing mode. Touching a sensing electrode, as used throughout this report, refers to the physical touching of the sensing electrode with an object such as a finger and/or that physically comes into contact with or touches any dielectric layers, coatings, plates, other layers or other materials that can be positioned between the sensing electrode and the finger through which the finger can be detected. Touching a sensing electrode may refer to an object such as a finger that is positioned on or near the sensing electrode to enable detection of the object using the capacitive sensing mode or the ultrasonic sensing mode.

[0088] If an object is determined to have been positioned near or in display 510, sensor 525, or other sensing electrode (e.g., based on reading voltage), then in block 615, if the object is a finger is It is likely that a finger can then be determined using ultrasonic detection. For example, in Figure 5, the controller circuit 520 may configure the sensor 525 to operate in an ultrasonic detection mode, as represented by changing the state of the switch in the electronic device 505. This results in the sensor 525 transmitting and receiving ultrasonic waves, as shown. discussed previously, to generate and provide fingerprint image data corresponding to a complete or partial fingerprint image of finger 515. The complete set of piezoelectric sensor pixels or a smaller collection of sensor pixels of sensor 525 may be used.

[0089] If the controller circuit 520 determines that the object is determined to be a finger (e.g., recognizes based on the data that the finger 515 has ridges and valleys or other characteristics of a fingerprint belonging to a finger, such as a acoustic impedance that falls within a finger's range), then in block 620, controller circuit 520 can “wake up” an application processor. For example, in Figure 5, application processor 530 may be activated (or activated, initialized, etc.) from a standby or off state by controller circuitry 520 asserting (e.g., changing a logic level from from a first level to a second, different level, such as low voltage to high voltage) an interrupt signal 560 upon determining that an object (e.g., finger 515) touching at least one of the sensing electrodes is, in fact, a finger using the 525 sensor in ultrasonic detection mode. The asserted interrupt signal may represent that the object is determined to be a finger and serves to instruct the application processor to authenticate the fingerprint. In some implementations, the controller circuit 520 or the application processor 530 may also power the display 510.

[0090] Then, at block 625, fingerprint authentication can be performed. For example, the application processor 530 may obtain the digital image data (e.g., by receiving the corresponding data stored in memory by the controller circuit 520) and then determine whether the fingerprint image data represents a fingerprint of an authorized user of the electronic device 505 by using, for example, a matching and authentication process. If so, then at block 630, the device may be unlocked or in some implementations unlocking the display 510 and returning to a home screen. For example, in Figure 5, at time 555, the display 510 is turned on and the electronic device 505 has been unlocked (e.g., most or all of the operational functionality and software of the electronic device 505 is now available for use). The image data for the authorized fingerprint may have been previously provided by the user (e.g., the owner), for example, during the establishment of the electronic device 505 or during the affiliation and establishment of the security features of the electronic device.

[0091] In more detail, sensor 525 can switch from operating in a capacitive sensing mode to an ultrasonic sensing mode (or ultrasonic sensing mode to capacitive sensing mode) based on how the electrodes are actuated. Figure 7 shows an example of a circuit schematic of a controller circuit configuring a fingerprint sensor to operate in a capacitive sensing mode. In Figure 7 a, controller circuit 520 includes a capacitive touch module 705 used to provide a signal to the receiver bias electrode 725 (e.g., receiver bias electrode 440 or transceiver bias electrode 460) of the sensor 525 If the switch 735 (e.g., implemented by an n-type or p-type metal-oxide semiconductor field-effect transistor (MOSFET), a thin-film transistor (TFT), etc.) is turned on (i.e., the switch is in a closed position, as depicted in Figure 7A, so that the output switch of the capacitive touch module 705 can drive the orientation electrode of the receiver 725).

[0092] In some implementations, the drive signal generated by the capacitive touch module 705 may include KT a frequency hopping signal having two or more frequencies that are applied in a predetermined sequence. For example, a sequence of three or five different frequencies may be generated via the capacitive touch module 705 and applied to the sensing electrode when operating in the capacitive sensing mode. In some implementations, the drive signal generated by the capacitive touch module 705 may include the pre-charge phase and charge-sharing phase of a conversion sequence, where a reference voltage is applied to an internal reference capacitor and a converter. analog to digital (ADC) to zero the ADC output in the pre-charge phase, and where the charge on the reference capacitor is shared via a sensing electrode with finger capacitance and any parasitic capacitances such as the PVDF capacitance in the charge sharing phase. The ADC output in the charge sharing phase provides a measure of the finger capacitance and whether a finger is present by comparing the ADC output to a touch detection threshold value. Consecutive measurements using the conversion sequence with each measurement allows a determination to be made of any changes in detected capacitance, such as a finger tap or finger lift. Additionally, the amplifier 715 of the controller circuit 520 may have its output disconnected (e.g., be in a high-impedance state, floating, not driven, triply set, etc. such that the amplifier 715 is not driving its output) such that that the capacitive touch module 705 can drive the bias electrode of the receiver 725 without any restraint. In some implementations, both amplifiers 715 and 720 may be turned off (i.e., turned off) to reduce power consumption because they are not required for sensor 525 to operate in a capacitive sensing mode. A receiver bias electrode 725, a capacitive voltage divider can be modeled with a voltage corresponding to the capacitance of the object on the touch screen being determined. The representations of amplifiers 715 and 720 are simplified. For example, they may include additional grounded input terminals. Drive signals and techniques for operating in a capacitive sensing mode may be applied to one or more sensing electrodes configured on a mobile device. The controller circuit 520 may be configured to provide (e.g., generate, switch, and apply) the drive signals to one or more sensing electrodes to operate in the capacitive sensing mode.

[0093] In operation, a user's finger may contact or be positioned sufficiently close to the polarization electrode of the receiver 725 of the sensor 525 and the additional capacitance due to the finger may be detected by the capacitive touch module 705. Detection of the finger in Contact with or near the orientation electrode of the receiver 725 may allow the controller circuit 520 to generate a touch-sensed signal that may, in turn, be used to wake up a mobile device, triggering additional sequences to authenticate the finger, or initiate another function, such as a home-button function.

[0094] In contrast, Figure 7B shows an example of a controller circuit schematic 520 configuring a fingerprint sensor 525 to operate in an ultrasonic detection mode. In Figure 7B, the control circuit 710 may drive amplifiers 715 and 720 and set the switch 735 to off (i.e., the switch is in an open position, as depicted in Figure 7B, such that the capacitive touch module 705 does not drive the receiver orientation electrode 725). This results in a receiver bias electrode 725 of the sensor 525 driven by the amplifier 715 and the diode bias electrode 730 (e.g., a control signal for controlling sensor 432 pixel circuits) driven by the amplifier 720. The bias electrode 725 of the receiver can be driven to a much higher voltage using amplifier 715. For example, to operate the sensor 525 in a capacitive sensing mode, the bias electrode 725 of the receiver can receive a signal of 1.8 volts (V ) by the capacitive touch module 705. In contrast, to operate the sensor 525 in an ultrasonic detection mode, the receiver bias electrode 725 may be provided with a 4-17 V signal by the amplifier 715. Additionally, the bias electrode of diode 730 can be driven according to the ultrasonic detection mode of operation. For example, the diode bias electrode may be driven with a first voltage level corresponding to a block mode during generation of an ultrasonic wave, a second voltage level corresponding to a sample mode when reflected ultrasonic waves are received by the sensor pixel circuitry, and a third voltage level corresponding to a hold mode for retaining the output electrical signals by the pixel circuit until the output electrical signals are clocked out of the sensor pixel circuitry.

[0095] Sensor 525 can be configured in a variety of other ways to operate in capacitive or ultrasonic detection modes. Figure 8 shows another example of a circuit schematic of a controller circuit for configuring a fingerprint sensor to operate in capacitive or ultrasonic detection modes. In Figure 8, the circuitry for the controller circuit 520 may be included within separate chips, for example, the controller circuit 520a may include an external capacitance touch module 705 while the controller circuit 520b includes the switch 735, amplifiers 715 and 720 , and control circuit 710. For example, to configure the sensor 525 in a capacitive sensing mode in Figure 8, the switch 735 can be turned on such that the capacitance touch module 705 drives the receiver bias electrode 725 and the output of amplifier 715 is adjusted to a high impedance state. The diode bias electrode 730 may be grounded (e.g., driven by the amplifier 720 so that it provides a voltage corresponding to ground). To configure the sensor 525 in an ultrasonic detection mode, the switch 735 can be opened such that the receiver bias electrode 725 is no longer driven by the capacitance touch module 705. Instead, amplifiers 715 and 720 can provide drive signals to the receiver bias electrode 725 and the diode bias electrode 730, respectively, when configured to operate in the ultrasonic detection mode. In various implementations, such as those shown in Figures 7a, 7B, and 8, the switch 735 may be physically located in the external capacitance touch module 705, in a controller ASIC associated with the controller circuit 520, within the sensor 525, or as a component external to the 705 touch module and ASIC controller.

[0096] The examples in Figures 7A, 7B and 8 use the receiver polarization electrode 725 for both capacitive and ultrasound detection. That is, the receiver bias electrode 725 can be used to detect the capacitance of an object resting on or near the receiver bias electrode and for ultrasonic detection to determine that the object is a finger by actuating the receiver bias electrode. 725 and associated circuit in sensor 525 differently.

[0097] However, separate electrodes can be used for capacitive detection and ultrasonic detection. For example, the receiver bias electrode 725 can be used for capacitive detection and the receiver bias electrode 725 and the diode bias electrode 730 can be used for ultrasonic detection. Figure 9 shows another example of a circuit schematic of a controller circuit for configuring a fingerprint sensor to operate in capacitive sensing and ultrasonic sensing modes. In Figure 9, the receiver bias electrode 725 may be driven by a capacitive touch module 705 and a diode bias electrode 730 may be grounded or set at another fixed potential to operate the sensor 525 in a capacitive sensing mode. In comparison, in the ultrasonic detection mode, the receiver bias electrode 725 may be grounded and the amplifier 720 may be driven to provide an active signal to the diode bias electrode 730 to enable ultrasonic detection. In this implementation, amplifier 715 and switch 735 may be removed or operated in a high impedance state relative to the examples in Figures 7a and 7B.

[0098] Figure 10 shows another example of a circuit diagram of a controller circuit for configuring a fingerprint sensor to operate in capacitive or ultrasonic detection modes. In Figure 10, the receiver orientation electrode 725 may be driven by the capacitance touch module 705 and the diode bias electrode 730 may be grounded (e.g., the control circuit 710 may drive the amplifier 720 such that a voltage corresponding to ground (e.g., 0 V in some scenarios) is applied to the diode bias electrode 730) to configure the sensor 525 in a capacitive sensing mode. In contrast, to configure the sensor 525 in an ultrasonic detection mode, the control circuit 710 may ground the orientation electrode of the receiver 725 by turning on the switch 1005 (e.g., n-type or p-type MOSFET) and provide an active signal to the diode bias electrode 730 using the amplifier 720 to operate the sensor 525 in the ultrasonic detection mode.

[0099] As discussed previously, the sensor 525 may be configured to be in a capacitive sensing mode to determine whether an object has touched or is positioned near the polarization electrode of the ultrasonic sensor receiver, and then subsequently configured to be in a mode ultrasonic detection method to determine whether this object is a finger. If the object is determined to be a finger, then an indicator may be asserted to indicate that an application processor should wake up and authenticate a fingerprint of the finger (e.g., determine whether it matches or is similar to a fingerprint of the owner or registered user of the device). If authenticated, then the application processor can turn on the touchscreen display and unlock the device for normal use.

[0100] Figure 11 shows an example of a high-level block diagram of a controller circuit, fingerprint sensor and application processor. In Figure 11, the capacitive touch analog front end 1110 and the ultrasonic analog front end 1115 include the circuit used to drive the sensor electrodes 525. The interface circuit 1105 (e.g., including control circuit 710, switch 1005, etc. . in the previous figures) selects the front end circuitry used to drive those electrodes. The microcontroller 1120 may determine whether the sensor 525 detects the presence of an object at or near the fingerprint sensor 525 in the capacitive detection mode and determine whether the interface circuit 1105 should switch the sensor 525 to operate in the ultrasonic detection mode. to determine whether the object is a finger. Information relating to the results of the capacitive sensing mode and the ultrasonic sensing mode may be stored in the memory 1125. For example, the microcontroller 1120 may store the data representing the capacitance measurement information of the sensor 525 in the capacitive sensing mode and the data image image from the 525 sensor in ultrasonic detection mode. In some implementations, data representing measurement conditions, such as temperature, whether a touch is a “strong” touch or a “weak touch” (e.g., the probability of a touch), and other metrics may also be stored. The clock generator 1135 may be a low-power clock generator for the wake-up timer 1130 that is used to operate the capacitive touch analog front end 1110.

[0101] If the object is a finger, an interrupt signal 560 may be asserted and provided to application processor 530. As a result, application processor 530 may read data stored in memory 1125, for example, via an interface I2C serial bus slave 1140. This restricts the application processor 530 to have access to the memory 1125 and not the microcontroller 1120, and therefore increases the security of the controller circuit 520 (e.g., by preventing access to the built-in memory of the microcontroller 1120). . If the data matches a fingerprint that matches or is sufficiently similar to an authorized fingerprint, then the application processor 530 may unlock the electronic device (e.g., a mobile device) and/or turn on the touchscreen display. touch. For example, authorized fingerprint data may be stored in memory and accessible by application processor 530. In some implementations, one or more portions of application processor 530 may wake up when an interrupt signal 560 is received and the application processor 530 may wake up. 530 applications can be instructed to authenticate the fingerprint of a finger. A query template generated during an authentication process from ultrasonic fingerprint image data received from sensor 525 may be compared to one or more registered templates generated during an enrollment process using one or more comparison algorithms to determine whether the fingerprint must be authenticated.

[0102] In some implementations, the microcontroller 1120 may authenticate the fingerprint based on data generated from the sensor 525. If the fingerprint is authenticated, then the microcontroller 1120 may assert interrupt signal 560 to instruct the application processor 530 to unlock the electronic device. When the fingerprint has been authenticated, a display of the mobile device and/or mobile device can be unlocked. In some implementations, when the mobile device and display are already active and unlocked from a previous authentication process, the mobile device may return to a home screen when a finger is placed on, for example, a home button or other electrode electrode. designated detection.

[0103] Figure 12 shows another example of a high-level block diagram of a controller circuit, fingerprint sensor and application processor. In Figure 12, application processor 530 includes a high-level operating system (HLOS) 1205, trust zone 1210, and SPI master 1215. Controller circuitry 520 may include SPI slave 1220. Application processor 530 may access stored data by the microcontroller 1120 via a serial peripheral interface (SPI) bus implemented by the SPI master 1215 and SPI slave 1220. For example, the SPI bus can operate in a secure fingerprint mode and a capacitive touch mode. In secure fingerprint mode, the trust zone 1210 of the application processor 530 may “own” the SPI bus and have access to the entire controller circuit 520 (e.g., the entire address space, including data generated and stored at from capacitive sensing mode and ultrasonic sensing mode). In capacitive touch mode, HLOS 1205 may “own” the SPI bus and application processor 530 may have restricted access to memory and registers that are storing data from sensor 525 that is in capacitive sensing mode.

[0104] Two-step capacitance detection and ultrasonic detection, described above, can reduce the number of false positives of an object touching the touch screen being a finger with an authenticable fingerprint, and therefore reduce power consumption. device current and increase device battery life. For example, in some scenarios, capacitance detection and two-step hybrid ultrasonic detection can reduce the current consumption of the electronic device from about 200 microamperes (μA) if only ultrasonic detection is used to unlock the electronic device below of 40 μA. Furthermore, the two-step techniques described here can reduce the number of false alarms from the application processor 530 and touch screen display. For example, some electronic devices may experience many fingerless touches, when the device is locked and switched it may inadvertently unlock or perform more intensive operations to verify or otherwise authenticate the touch.

[0105] As discussed previously, sensor 525 may include material such as PVDF or PLT PVDF-TrFE that is part of the capacitive voltage divider used to detect a touch. Materials such as PVDF or PVDF-TrFE may experience a greater temperature dependence of capacitance than other dielectric materials such as glass, and therefore the 525 sensor may need additional temperature-based calibration. This contrasts with sensors in other capacitive sensing systems in which the determination of capacitance does not depend strongly on temperature. Accordingly, in some implementations, the capacitance determined using sensor 525 may be adjusted based on the temperature, e.g., of sensor 525.

[0106] Figure 13 shows an example of adjusting a capacitance determined using the temperature-based fingerprint sensor. In Figure 13, the current temperature of sensor 525 can be determined (e.g., by controller circuit 520) to generate current temperature 1305 using, for example, a temperature-sensitive p-n junction diode formed as part of the sensor circuit on or at the sensor substrate. Additionally, the average temperature of the sensor 525 may be determined to generate the average temperature 1310. The average temperature 1310 may be an average of the sensor operating several past temperatures of the sensor 525 and incorporate the current temperature 1305 to provide a new average temperature. updated 1310 of sensor 525. In some implementations, the average temperature may be the output of a first- or second-order finite impulse response (FIR) filter or infinite impulse response (IIR) filter that operates on a stream of measurements of temperature from the temperature sensitive diode. The current temperature 1305 can be subtracted from the average temperature 1310 (or vice versa) to generate ALU 1320 representing the difference in temperature between the current temperature 1305 and the average temperature 1310. ALU 1320 can then be adjusted (e.g., multiplied) by calibration factor 1315. Calibration factor 1315 may be an adjustment that represents process variations and other deviations that may be corrected during a calibration process based on how the sensor 525 was manufactured. Consequently, capacitance deviation 1325 may be generated. The measured capacitance 1330 may be the capacitance of the object (or portion thereof) on or near the receiver bias electrode as measured by the sensor 525. The measured capacitance 1330 may then be adjusted (e.g., compensation by addition, subtraction, etc. .) based on the capacitance shift 1325 to generate the adjusted capacitance 1335. If the adjusted capacitance 1335 corresponds to a finger-like capacitance, then the ultrasonic detection mode can begin, as discussed previously.

[0107] Figure 14 shows an example of a flowchart for adjusting the capacitance determined using the fingerprint sensor. In Figure 14, in block 1405, the temperature can be determined. For example, controller circuit 520 may determine temperature when sensor 525 is operating in capacitive sensing mode. Next, in block 1410, the average temperature can be determined. For example, the controller circuit 520 may keep track of an operating average temperature of the sensor 525 and therefore the operating average may be updated to take into account the temperature determined in block 1405. The operating average may be based on in hundreds or thousands of measurements, or more.

[0108] In block 1415, the difference between the temperature determined in block 1405 and the average temperature determined in block 1410 can be determined. In block 1420, controller circuit 520 may use the difference obtained from block 1415 and adjust the difference by applying a calibration factor to generate a capacitance shift. Next, in block 1425, the measured capacitance can be determined. For example, the sensor 525 may be in capacitive sensing mode and a voltage may be read by the controller circuit 520, as discussed previously, and correlated with a capacitance that may be used to determine whether the object touching or near the polarization electrode of the receiver is a finger. In block 1430, the measured capacitance can be adjusted by the capacitance shift to generate an adjusted measured capacitance. This adjusted measured capacitance represents the capacitance of the object, or a part of the object, while taking into account the temperature dependence of the sensor 525 in determining the capacitance. In block 1435, the sensor can be configured to operate in ultrasonic detection mode, based on the adjusted measured capacitance. For example, if the adjusted measured capacitance is within a threshold capacitance range representative of a finger, then the controller circuit 520 may configure the sensor 525 to operate in the ultrasonic detection mode, as discussed previously.

[0109] As another example of adjusting the measured capacitance 1330 to provide an adjusted capacitance 1335, the measured capacitance 1330 may be adjusted to compensate for manufacturing variations of the fingerprint sensor 525. Manufacturing variations may include variations in the dielectric constant and thickness of the cover glass, layers of paint, various adhesives and other layers formed during sensor manufacturing. Manufacturing variations may lead to unit-to-unit variations in capacitance change when a user touches or is positioned near a fingerprint sensor sensing electrode. The change in capacitance when a user touches or is positioned near a fingerprint sensor sensing electrode can be referred to as the “touch capacitance”. Variation in touch capacitance due to manufacturing variations can alter the response due to a “partial touch” where a user's finger is in contact with only a portion of the sensor's active area. Variation in touch capacitance from unit to unit and sensitivity to a user's partial touch can lead to a less than satisfactory, if not accommodated, user experience. For example, a thicker cover glass, a layer of paint or adhesive and/or a lower cover glass, paint or adhesive dielectric constant will lead to lower touch capacitance without corresponding adjustments, and the mobile device may be less sensitive to a user's partial touch and may need to be contacted by a larger portion of a finger for finger detection compared to another mobile device with nominal thicknesses and dielectric constants. Alternatively, a thinner coating layer of glass, paint or adhesive and/or higher coverage glass, paint or adhesive dielectric constant will lead to greater touch capacitance, and the mobile device may be more sensitive to partial touch of a finger, which may lead to inadvertent detection by a fingerless object.

[0110] Method of calibrating a capacitive sensing electrode of a fingerprint sensor to detect a touch of a finger and to account for various manufacturing variations that utilize the fingerprint sensor to determine the contact area of a finger or finger of a finger calibration target that is in contact with or in partial contact with the active area of the fingerprint sensor and then utilizing the determined contact area to provide an adjusted capacitance 1335. The finger calibration target may include a finger-like material that can be positioned over the detection electrode of the fingerprint sensor during a calibration sequence performed in a factory during an assembly and testing process. In some implementations, a user's touch capacitance may be measured during a fingerprint enrollment process and adaptively refined during subsequent fingerprint authentication processes.

[0111] During a first step, a touch capacitance can be measured and estimated and a fingerprint image can be acquired during a registration process or a subsequent authentication process. Capacitance measurement and fingerprint image acquisition can be taken consecutively during the same finger contact event. For example, the fingerprint image may be acquired before the capacitance measurement or the fingerprint image may be acquired after the capacitance measurement. During a second step, the contact area of the user's finger on the active area of the fingerprint sensor may be estimated or otherwise determined from the acquired digital image using, for example, visual features such as ridges, valleys and minutiae. fingerprint, or using differences and variances in gray level values of small blocks of sensor pixels in the ultrasonic sensor array to determine a fingerprint boundary between air and an object such as a finger and determine the contact area of the determined fingerprint limit. During a third step, a total contact touch capacitance can be calculated, which is the touch capacitance when the user's finger comes into contact with the entire active area of the sensor. The total contact touch capacitance can be calculated from the ratio of the active sensor area divided by the determined finger contact area. The calculated total contact touch capacitance may be refined by producing additional capacitance measurements and finger contact area determinations and calculating an average, median, or other appropriate statistical measure of the total contact touch capacitance. Full contact touch capacitance can be initially calculated during fingerprint scrolling and adaptively adjusted or refined during subsequent fingerprint association and authentication processes. During a fourth step, a touch detection threshold and a lift detection threshold may be adjusted or otherwise determined in accordance with the total contact touch capacitance, which may be based in part on the contact area of the finger in contact with the fingerprint sensor. In some implementations with a nominal coating glass thickness, the touch detection threshold may be set equal to about one-quarter of the total touch capacitance. For example, if the total contact touch capacitance is determined to be 100 picofarad (pF), the touch detection limit can be set equal to 25 pF. In an example where the cover glass of the mobile device is thinner than nominal and the total contact touch capacitance is determined to be 110 pF, the touch detection limit can be set equal to 27.5 pF. In an example where the cover glass of the mobile device is thicker than nominal and the total contact touch capacitance is determined to be 90 pF, the touch detection threshold can be set equal to 22.5 pF. Similarly, the lift detection threshold, which helps determine when a finger has been lifted from the sensor, can be adjusted accordingly. In some implementations, once a probe has been raised and the measured capacitance is below the touch detection threshold, the non-contact baseline capacitance can be measured and stored as a line non-touch capacitance value. baseline that can be compared with the partial capacitance or partial full touch capacitances and the previous non-touch baseline capacitance values to determine or adjust the touch detection limit or the lift detection limit. In some implementations, the touch detection threshold and/or the lift detection threshold may be stored with a user's registration templates generated during a registration process.

[0112] To further reduce the temperature dependence of the measured capacitance 1330, the capacitance of the piezoelectric receiving layer 436 can be canceled using an active shielding method. The capacitance of the piezoelectric receiver layer 436 (or piezoelectric transceiver layer 456 in some implementations) may be an increased function of temperature as the dielectric constant of the PVDF or PVDF-TrFE piezoelectric layer may vary with temperature more than other materials. dielectrics in the sensor 525. When the active shielding method is employed, one or more lower electrodes (such as one or more pixel input electrodes 438) that are coupled to a lower surface of the piezoelectric receiving layer 436, may be actuated with a stored version of the drive signal that is used to drive the receiver bias electrode 440 (or transceiver bias electrode 460 in some implementations). The temporary drive signal generated by the controller circuitry associated with the controller may be provided to one or more electrodes of the fingerprint sensor when the fingerprint sensor is configured in capacitive sensing mode. The receiver bias electrode 440 can serve as a detection electrode and as a top electrode for the capacitor with the piezoelectric receiver layer 436 as the dielectric layer. For example, if the drive signal applied to the receiver bias electrode 440 is increased by 0.5 V, the temporarily stored drive signal applied to the bottom electrode(s) of the piezoelectric receiver layer 436 may also be increased by 0.5 V. Similarly, if the drive signal applied to the receiver bias electrode 440 is decreased by 0.7 V, the buffered drive signal applied to the bottom electrode(s) of the piezoelectric receiving layer 436 may also be decreased by 0.7 V. bottom(s) of the piezoelectric receiver layer 436 can therefore serve as an active shield to cancel the capacitance of the piezoelectric receiver layer 436 along with the associated temperature dependence. In some implementations, the drive signal used to drive the receiver bias electrode 440 in a capacitive sensing mode may be generated by active cancellation circuitry which may include amplifiers and signal conditioning circuits such as continuous time filters. In some implementations, the active cancellation circuit may be implemented in the controller applied to the receiver bias electrode 440 as input to generate the temporarily stored drive signal that may be connected to the bottom electrode(s) of the piezoelectric receiver layer 436.

[0113] The microcontroller 1120, the controller circuit 520, and the application processor 530 may include a variety of circuits to implement the techniques discussed herein. For example, the microcontroller 1120, the controller circuit 520, and the application processor 530 may each include (or have access to) one or more processors, memory, and other hardware components or circuits. Processors can be used to execute instructions stored in memory to implement the techniques described herein.

[0114] Figure 15A shows an example of a flowchart for a method of using a capacitive detection mode and an ultrasonic detection mode to detect the presence of an object using a fingerprint sensor 525, as illustrated in Figure 5 and described with respect to Figures 1 to 14. When an object such as a finger 515 is positioned on or near a sensing electrode of the fingerprint sensor 525, the finger may be detecting the use of the fingerprint sensor operating in a capacitive sensing mode, as shown in block 1505. A finger detected using the capacitive sensing mode may also be detected with the fingerprint sensor operating in ultrasonic mode, as shown in block 1510. In some implementations, the fingerprint sensor may be configured to operate in the ultrasonic detection mode in accordance with the present invention a touch of a finger or other object has been detected in the capacitive detection mode. The combination of capacitive detection and ultrasonic finger detection can be used to determine an object detection state with a greater level of certainty, as shown in block 1515. An affirmative object detection state can be used, for example, to send an interrupt signal to an associated application processor and proceed with shutting down the application processor, authenticating the finger and unlocking the device. In some implementations, the interrupt signal may be provided to the application processor to represent that a finger corresponding to a touch has been detected by the fingerprint sensor operating in capacitive detection mode, ultrasonic detection mode, or both. capacitive detection mode and ultrasonic detection mode.

[0115] Figure 15B shows an example of a flowchart for a method of using a capacitive detection mode to initially detect the presence of an object, as shown in block 1520. If no object or finger has been detected, the detection mode Capacitive sensing may be invoked on a periodic basis (e.g., on the order of five to twenty times per second) as represented by the “no” path of block 1525. If an object/finger has been detected, then a touch event may be reported as shown in block 1530. Reporting the touch event may include sending an interrupt signal to the application processor as described with respect to block 1515 of Figure 15, as shown in block 1535 and block 1540, and to report when the object/finger has been lifted as shown in block 1545. The reported finger lift event may cause the sensor system to return to the low power capacitive sensing mode as shown in block 1520. In some implementations, a controller, fingerprint sensor, and one or more sensing electrodes may be configured to report a finger lift event while operating in the capacitive sensing mode, the ultrasonic sensing mode, or both the capacitive sensing mode and the ultrasonic detection.

[0116] Figure 15C shows an example of a flow chart for a method of using a capacitive detection mode to initially detect the presence of an object, as shown in block 1550. If no object or probe has been detected, the detection mode Capacitive sensing may be invoked on a regular or periodic basis, as shown with the “no” path from block 1555. If an object/finger has been detected, then a touch event may be reported. Either the capacitive sensing mode or an ultrasonic sensing mode can be used to almost continuously determine that the object/finger remains in contact with or is close to the sensing electrode, as shown in block 1560 and block 1565. When the presence of the object/finger is no longer detected with both capacitive and ultrasonic detection modes, a finger lift event may be reported as shown in block 1570 and block 1575. The reported finger lift event may cause the sensor system to return to low power capacitive sensing mode as shown in block 1550.

[0117] Alternatively or in addition to the capacitance and ultrasonic sensing methods shown and described with respect to Figures 15A-15C, decision logic for waking up the application processor and authenticating a fingerprint may use input from one or more accelerometers and gyroscopes included in the mobile device. In-device accelerometers and gyroscopes may provide indication of changes in the movement and/or orientation of the mobile device that may indicate the user's intent to wake up and use the mobile device. Accelerometers and gyroscopes may include one or more microelectromechanical sensors (MEMS), analog mixed-signal and signal processing circuits, and microcontrollers. Accelerometers and gyroscopes may include embedded firmware and algorithms, which can execute algorithms to detect and quantify magnitude and direction changes in the movement and/or orientation of the mobile device. Accelerometers and gyroscopes along with associated firmware and algorithms can be included in independent modules on the mobile device. In some implementations, the accelerometers and gyroscopes may leverage signal processing and/or computational capabilities and control functions of a shared core-sensor device or a dedicated section such as a low-power island of the application processor in the mobile device. Output signals from on-device accelerometers or gyroscopes that indicate a change in motion or a change in orientation of the mobile device may be used via the controller to configure one or more sensing electrodes in capacitive sensing mode or sensing mode. ultrasonic in anticipation of an imminent touch event.

[0118] In some implementations that utilize motion and/or orientation detection by accelerometers and gyroscopes, the capacitive and/or ultrasonic detection rate for finger detection may be changed based on indications from accelerometer and gyroscope signals. For example, motion detection may lead to capacitive detection and/or ultrasonic detection being performed more frequently. In another example, when no movement or change in orientation has been detected for an extended period of time, capacitive and/or ultrasonic detection for finger detection may be performed less frequently. The controller may be configured to adjust a finger detection rate in capacitive detection mode or in ultrasonic detection mode upon indication of a change in motion or a change in orientation of an on-device accelerometer or an on-device gyroscope.

[0119] Another example of using motion and/or orientation detection by in-device accelerometers and gyroscopes, the detection thresholds used by the capacitive detection and ultrasonic detection algorithms can be changed based on accelerometer and gyroscope inputs. Detection of rotation of the mobile device towards the user by accelerometers and/or gyroscopes may indicate a greater probability that the user intends to use the mobile device and detection thresholds for capacitive sensing and ultrasonic sensing may be configured to a higher level. low. Alternatively, detection of rotation of the mobile device away from the user by accelerometers and/or gyroscopes may indicate a lower likelihood that the user will wish to use the mobile device, and the capacitive sensing and ultrasonic sensing thresholds may be configured with a level higher. The controller may be configured to adjust a touch detection threshold and/or a finger lift detection threshold upon indication of a change in movement or a change in orientation of an on-device accelerometer or an on-device gyroscope.

[0120] In some implementations, the array of accelerometers and gyroscopes (e.g., angular rate sensors) in the mobile device may be configured to wake portions of the device in what may be referred to as a shake-and-wake operation. Output signals from one or more accelerometers and/or gyroscopes in the sensor array may be received by an ASIC or an applications processor associated with the fingerprint sensor to increase the finger detection rate for capacitive or O detection mode. ultrasonic detection mode and to quickly allow a user to be authenticated. The shake and wake operation may, in some examples, turn on a portion of a display to assist the user in an authentication process. In some implementations, the touch detection threshold can be lowered in both capacitive detection mode and ultrasonic detection mode by detecting a specific range and sequence of output signals from the on-device accelerometers and gyroscopes. In some implementations, the touch detection threshold may be set to zero for capacitive detection mode or for ultrasonic detection mode if the range and sequence of output signals from the accelerometers and gyroscopes on the device satisfy a criterion of acceptance to reduce the latency associated with the authentication process.

[0121] Figure 16A shows an example of using a capacitive detection mode and an ultrasonic detection mode with a fingerprint sensor 525 provided with one or more associated detection electrodes 1641, 1642 to awaken an electronic device 505. Device Electronic device 505 may include a controller circuit 520 that may switch sensor 525 to operate between a capacitive sensing mode and an ultrasonic sensing mode as described above with respect to Figure 5 and Figure 6. Electronic device 505 may be in a locked state in which an application processor 530 and a display 510 of the electronic device 505 are turned off or are in a low-power standby mode. For example, in Figure 16A at time 1650, electronic device 505 is in a locked state. This results in the display 510 being turned off and the application processor 530 shut down or operating or in a relatively low power standby mode.

[0122] An object such as a finger 515 can be detected using the capacitive detection mode and one of the detection electrodes 1641, 1642. For example, in Figure 16A, at time 1650, the finger 515 is positioned at or near the electrode detection electrode 1641 and is detected using sensor 525 with detection electrode 1641 operating in a capacitive detection mode. In the implementation shown, the sensing electrodes 1641 and 1642 are conductive electrodes (e.g., interdigitated electrodes) formed under the cover glass of the electronic device 505. In some examples, the sensing electrodes 1641 and 1642 may be screen printed on the inside of the cover glass or formed as part of a flexible (e.g., “flex”) printed circuit that is adhered to the interior of the cover glass and which can be connected directly to the finger sensor 525. In some implementations, the detection electrodes 1641 and 1642 may be configured as substantially square, rectangular, or other suitably configured electrodes.

[0123] If an object such as a finger 515 is detected using the capacitive detection mode, then whether the object is a finger can be determined using an ultrasonic detection mode. The sensor 525 may transmit and receive ultrasonic waves to provide image data corresponding to a complete or partial digital image of the finger 515. If it is determined that the object is a finger, then the controller circuit 520 may awaken the applications processor 530 and In some implementations, the controller circuit 520 or the application processor 530 may also power the screen 510 and fingerprint authentication may be performed. If the fingerprint image data matches a fingerprint of an authorized user of the electronic device 505, the electronic device 505 can be unlocked. For example, in Figure 16A at time 1655 when the finger 515 moves over the sensor 525, the capacitive reading mode using detection electrodes 1641, 1642 or a sensor receiver bias electrode 525 may be intertwined with the detection mode. ultrasound to detect and authenticate the finger 515 after which the display 510 can be turned on and the electronic device 505 unlocked. In some implementations, the sensing electrodes 1641 and 1642 associated with the fingerprint sensor 525 may be configured and coupled to the controller circuit 520 such that these signals may be provided to and from the sensing electrodes 1641 and 1642, when operating. the fingerprint sensor 525 in capacitive sensing mode, while the receiver bias electrode of the sensor 525 may be configured and coupled to the controller circuitry 520 such that signals may be provided to and from the receiver bias electrode, when operating the 525 fingerprint sensor in ultrasonic detection mode. As described above with respect to Figure 16 a, the detection electrodes 1641 and 1642 and the fingerprint sensor receiver polarization electrode 525 may be positioned under a cover glass of a mobile device.

[0124] Figure 16B shows another example of using a capacitive sensing mode and an ultrasonic sensing mode with a fingerprint sensor 525 and one or more sensing electrodes 1643, 1644 associated with the fingerprint sensor 525 to wake up 16A, the electronic device 505 may include a controller circuit 520 that may switch the sensor 525 and/or sensing electrodes 1643, 1644 to operate between a capacitive sensing mode and a capacitive sensing mode. ultrasonic detection as described above with respect to Figure 5 and Figure 6. As shown in Figure 16B at time 1650, the electronic device 505 may be in a locked state. The finger 515 may be detected using a capacitive detection mode and/or an ultrasonic mode with one of the detection electrodes 1643, 1644 or a sensor receiver bias electrode 525. In the implementation shown, the detection electrodes 1643 and 1644 include conductive electrodes and a piezoelectric layer positioned between the conductive electrodes that are disposed under the glass cover or display 510 of the electronic device 505. The sensing electrodes, the piezoelectric layer and the conductive electrodes form a sensor stack (i.e., a button ) which can be used for capacitive detection and ultrasonic detection in both capacitive detection mode and ultrasonic detection mode. In some examples, the detection electrodes 1643 and 1644 may be formed on a separate substrate or system as part of a flexible printed circuit that is adhered to the interior of the cover glass. In some implementations, the detection electrodes 1643 and 1644 and the underlying piezoelectric layers with associated excitation electrodes may be configured as substantially square or rectangular. In some implementations, the sensing electrodes 1643 and 1644 and the underlying piezoelectric layers may be manufactured in common with and on the same substrate as the sensor 525. In some implementations, the sensing electrodes 1643 and 1644 of FIG. 16A (and/or the detection electrodes 1641 and 1642 of Figure 16A) in coordination with sensor 525, can be used as menu, home and return buttons, although other functions and button definitions have been contemplated.

[0125] If a finger 515 is detected using the capacitive detection mode and/or the ultrasonic detection mode, then the controller circuit 520 may wake up the application processor 530 and turn on the display 510 or perform another function such as validate or authenticate the finger 515. For example, as the finger 515 moves over and above the sensor 525, the capacitive sensing mode and/or the ultrasonic mode using sensing electrodes 1643, 1644 or a sensor receiver bias electrode 525 can detect the finger 515 and the sensor 525 can authenticate the finger 515 after which the display 510 can be turned on and the electronic device 505 unlocked as illustrated in Figure 16B. In some embodiments, one or more of the detection electrodes 1643, 1644 or the sensor receiver bias electrode 525 may be configured to detect a finger gesture.

[0126] Figure 17 shows a side view of a configuration 1700 with a fingerprint sensor 525 and one or more capacitive and/or ultrasonic detection electrodes 1745 associated with the fingerprint sensor 525 positioned under a cover glass of a display 510. The sensor 525 and/or the sensing electrodes 1745 may be configured to operate in a capacitive sensing mode or an ultrasonic sensing mode as described above with respect to Figures 1 to 16B in the example shown in Figure 17, the sensor 525 is positioned beneath a portion of a common cover layer that may serve as a cylinder 306 for sensor 525 and as a touch screen or cover glass for screen 510. Fingerprint sensor 525 may have a separate substrate or in some implementations have a common substrate with the display 510. The detection electrodes 1745 may be screen printed on the inside of the cover glass or formed as part of a flexible cable (not shown) that is coupled to the inside of the glass covering and which may be connected directly to the finger sensor 525. In some implementations, the sensing electrodes 1745 may include one or more conductive electrodes and a piezoelectric layer positioned between interconnecting conductive electrodes. In some implementations, the detection electrodes 1745 may be formed on a separate substrate or system part of a flexible printed circuit that is adhered to the interior of the cover glass. In some implementations, the sensing electrodes 1745 and the underlying piezoelectric layers with interconnecting electrodes may be configured as substantially square or rectangular. In some implementations, the sensing electrodes 1745 and the underlying piezoelectric layers may be coaxially manufactured with and on the same substrate as the sensor 525. In some implementations, the sensor 525 and the sensing electrodes 1745 may be peripheral to the active area of the display. which may include a display substrate layer 1720 and a display color filter glass layer 1740. In alternative configurations, the sensor 525 and/or the detection electrodes 1745 may be positioned in a notch, on the side, or on the back of a mobile device enclosure (not shown). In some implementations, sensor 525 may be positioned as part of an ultrasonic button. The ultrasonic button can be mechanical or non-mechanical. For example, the ultrasonic button can be mechanically coupled to an electromechanical switch. The ultrasonic button can be authentication or in some implementations non-authentication.

[0127] Figure 18 shows an example of using a capacitive sensing mode and an ultrasonic sensing mode with a fingerprint sensor 525 positioned behind a display 510 of an electronic device 505 to activate the electronic device 505. The device electronic device 505 may include a controller circuit 520 that may switch sensor 525 to operate between a capacitive sensing mode and an ultrasonic sensing mode as described above with respect to Figure 5 and Figure 6. The electronic device 505 may initially be in a state locked in which a display 510 and an application processor 530 of the electronic device 505 are turned off or in a low-power standby mode, as illustrated in Figure 18 at time 1850. to the sensor 525 using the capacitive sensing mode and/or the ultrasonic sensing mode, a portion of the display 510 may turn on to indicate and highlight the position where the fingerprint sensor is located as illustrated in Figure 18 at time 1855. As depicted In Figure 18, text indicating “Place Finger Here to Unlock” is shown along with a graphically generated circular icon 565, although many other icons and/or text provided as guidance to a user to indicate the position of the fingerprint sensor have been contemplated. . The capacitive and/or ultrasonic sensing modes may continue to be used until the finger 515 is converted into an image, at which time the image data may be analyzed and the electronic device 505 unlocked if the authentication process is successfully performed. The sensor 525 may be positioned beneath a portion of the display 510, which may be an LCD screen, an OLED screen, or another type of display. In some implementations, one or more electrodes of a touch screen of the electronic device 505 may serve as a sensing electrode for the fingerprint sensor 525 when operating in a capacitive sensing mode, allowing signals from non-active portions of the display 510 without the fingerprint sensor 525 are ignored by the controller circuit 520 while allowing signals due to a finger touch of active portions of the display 510 with the fingerprint sensor 525 to be detected, further reducing inadvertent activation of the electronic device 505 .

[0128] Figure 19 shows a side view of a configuration 1900 with a fingerprint sensor 525, positioned behind a portion of a monitor 510. The fingerprint sensor 525 is positioned below an LCD or OLED display 510 and a cover glass or touch screen window that serves as a cylinder 306 for the sensor 525. The sensor 525 and associated sensing electrodes may be configured to operate in a capacitive sensing mode or an ultrasonic sensing mode as described above with respect to Figures 1 to 16B. In some implementations, the sensor 525 may be located near the top, bottom, edge, or somewhere in an interior portion of the display, which may include a TFT substrate layer 1720 and other layers 1740 of an LCD or OLED screen. In other examples, the sensor 525 may be positioned underneath or behind the entire display 510. In other examples, the sensor 525 may be integrated within the display TFT substrate layer 1720. The sensor 525 may be integrated with the display substrate Display TFT, sharing common TFT substrates with the active area of the 525 sensor that covers some, none, or all of the active area of the display.

[0129] Figure 20 shows an example of a flowchart for a method 2000 for guiding a user of an LCD or OLED display device to position a finger above an under-LCD or under-OLED fingerprint sensor. Graphical display-based icons can be useful for secondary display configurations since the use of colored inks or other permanent indicia to mark the position of the fingerprint sensor may obstruct a user's view of the display device (e.g. , a mobile device or an electronic device) can be avoided. In some implementations, the presence of a finger can be detected via capacitive sensing electrodes of a touchscreen overlaying the screen while the screen is off. In some implementations, dedicated sensing electrodes as part of or near the ultrasonic fingerprint sensor may be used to detect the presence of a finger. In block 2005, a user's finger positioned on a display surface may be detected using a capacitive sensing mode, such as described with respect to Figures 5-12 above with, for example, the touch screen or a touch electrode. dedicated detection. In the 2010 block, after detecting the presence of the finger, a fingerprint sensor icon may be illuminated on the display. In some implementations, the screen may be partially unlocked to display only the fingerprint sensor icon or other selective information to guide the user. In some implementations, a portion of the display may be illuminated while in a low power mode, and the icon may be highlighted or other selective information provided to the user when the finger is detected. In block 2015, a finger may be detected on the display above the fingerprint sensor window using a capacitive detection mode, an ultrasonic detection mode, or both a capacitive and an ultrasonic detection mode, as described above. With respect to Figures 15A-15C in block 2020, the user can be authenticated and the display unlocked. In alternative configurations, such as using an OLED screen, the display may continuously show the fingerprint sensor icon or other selective information using a subset of the display pixels to guide the user while the mobile device remains locked.

[0130] Figure 21 shows an example of using a capacitive detection mode and an ultrasonic detection mode with a fingerprint sensor 525 and one or more associated detection electrodes 2141, 2142, 2143 and 2144 positioned behind a display. 510 of an electronic device 505 to wake up or otherwise interact with the electronic device 505. Sensors 2141, 2142, 2143 and 2144 may include an underlying piezoelectric layer and conductive electrodes to form a sensor stack (i.e., an ultrasonic button). which can be used for capacitive detection or detector for ultrasonic detection in both capacitive detection mode and ultrasonic detection mode. The electronic device 505 may include a controller circuit 520 that may switch the sensor 525 with a receiver bias electrode and/or sensing electrodes 2141, 2142, 2143, 2144 to operate between a capacitive sensing mode and an ultrasonic sensing mode. as described above with respect to Figure 5 and Figure 6. The electronic device 505 may initially be in a locked state in which the display 510 and an application processor 530 of the electronic device 505 are turned off or in a low power standby mode, as illustrated in Figure 21 at time 2150. When an object such as a finger 515 is detected on or near the sensor 525 or detection electrodes 2141, 2142, 2143, 2144, using the capacitive detection mode and/or the detection mode ultrasonic, a portion of the display 510 may turn on to highlight where the fingerprint sensor is located as illustrated in Figure 21 at time 2155. Text, such as “put your finger here to unlock” or other suitable text may be displayed along with a graphically generated circular icon 565 as applicable to guide a user on which to place a finger to unlock the mobile device or to initiate another function such as a payment function. The capacitive and/or ultrasonic sensing modes may continue to be used until the finger 515 is converted into an image, at which time the image data may be analyzed and the electronic device 505 unlocked if the authentication process is successfully performed. The sensor 525 and the detection electrodes 2141, 2142, 2143 and 2144 may be positioned beneath a portion of the display 510, such as an LCD display or an OLED display. The sensor 525 and the sensing electrodes 2141, 2142, 2143, 2144 may continue to sense and/or authenticate the user or perform other functions in response to movements of the finger 515 such as tapping, double-tapping, tapping, rotating, pressing or otherwise. indicative movement. In some embodiments, one or more of the sensing electrodes 2141, 2142, 2143, 2144 or the sensor receiver bias electrode 525 may be configured to detect finger gestures. Sensing electrodes 2141, 2142, 2143, 2144 may be coupled to one or more piezoelectric layers to enable capacitive and/or ultrasonic sensing. As illustrated in Figure 21, the sensing electrode 2141 and the sensing electrode 2142 can be used to detect movements in the left-to-right direction or the right-to-left direction, while the sensing electrode 2143 and the detection 2144 can be used to detect movements in the top-down direction or the bottom-up direction. Additional sensing electrodes (not shown) associated with the fingerprint sensor 525 may be located diagonally to the fingerprint sensor 525 and in other locations relative to the fingerprint sensor 525 such as a three-by-three (3x3) arrangement or larger to further assist with gesture detection. Detection sensors 2141, 2142, 2143 and 2144 may include one or more piezoelectric layers positioned between conductive electrodes to enable operation in a capacitive mode or an ultrasonic mode.

[0131] Figure 22 shows a side view of a configuration 2200 with a fingerprint sensor 525 and one or more associated detection electrodes 2243, 2244 positioned behind a display 510 of a mobile device. The fingerprint sensor 525 and detection electrodes 2243, 2244 are positioned beneath an LCD or OLED display 510 and a glass or touch screen cover that serves as a cylinder 306 for the sensor 525. The Sensor 525 is/ or sensing electrodes 2243, 2244 or other associated sensing electrodes, such as one or more electrodes in or on the touch screen (e.g., a “touch screen electrode”) may be configured to operate in a mode of capacitive sensing or an ultrasonic sensing mode, as described above with respect to Figures 1 through 21. In some implementations, the sensor 525 may be located near the top, bottom, edge, or somewhere on an interior portion of the display, which may include a TFT substrate layer 1720 and other layers 1740 of an LCD or OLED screen. In other examples, the sensor 525 may be positioned underneath or behind the entire display 510. In other examples, the sensor 525 may be integrated within the display TFT substrate layer 1720. The sensor 525 and the sensing electrodes 2243, 2244 can be integrated with the display TFT substrate, sharing common TFT substrates with the active area of the sensor 525 covering part, none or all of the active area of the display. Detection electrodes 2243, 2244 may be coupled to one or more piezoelectric layers and associated conductive electrodes to enable operation in capacitive and/or ultrasonic modes.

[0132] Figure 23 a shows an example of using a capacitive detection mode and an ultrasonic detection mode in a configuration 2300 with a fingerprint sensor 525 and one or more associated detection electrodes 2341, 2342, 2343, 2344 positioned behind a back cover of an electronic device 505. Sensors 2341, 2342, 2343, 2344 may include underlying piezoelectric layers and electrodes to form a sensing stack that can be used for capacitive sensing or for ultrasonic sensing in either sensing mode capacitive as in ultrasonic detection mode. The fingerprint sensor 525 may be configured to wake up or otherwise interact with the electronic device 505. The electronic device 505 may include a controller circuit 520 that may switch the sensor 525 with a receiver bias electrode and/or sensor electrodes. detection modes 2341, 2342, 2343, 2344 to operate between a capacitive detection mode and/or an ultrasonic detection mode as described above with respect to Figure 5 and Figure 6. Capacitive and/or ultrasonic detection modes can be used to detect the finger 515 and perform other functions, such as the portable electronic device 505 authenticating a user, or interacting with an application running on the network the application processor 530 such as taking an image while the electronic device 505 is underwater. The sensor 525 with a receiver bias electrode and sensing electrodes 2341, 2342, 2343, 2344 may be configured to continue to sense and/or authenticate the user or perform other functions in response to detecting finger gestures and finger movements. 515 such as tapping, double tapping, tapping, pressing or other movement indicative of such a striking gesture as represented with arrow 2360, as illustrated in Figure 23B. Additional ultrasonic and/or capacitive sensing electrodes (not shown) associated with the fingerprint sensor 525 may be located diagonally to the fingerprint sensor 525 or at other locations relative to the fingerprint sensor 525 to further assist in gesture detection .

[0133] In some implementations, the rear cover of a mobile or electronic device such as electronic device 505 in configuration 2300 shown at t in Figures 23A and 23B, may be formed from any suitable material that can be acoustically coupled to the print sensor. digital ultrasonic 525. For example, the back cover may be formed from one or more of glass, plastic, ceramic, sapphire, metal or metal alloy including titanium, aluminum or an aluminum alloy, or laminates thereof.

[0134] Alternative to or in addition to the capacitance and ultrasound detection methods shown and described with respect to Figures 15A-15C and the shaking and waking operations with in-device accelerometers and angular rate sensors described above, piezoelectric force signals and generated sounds by a user interacting with the mobile device can be included in various aspects of hybrid activation. A user may touch, tap, rub, press, bend, flex, pick up, squeeze, or otherwise physically interact with the housing or display of a mobile device. Physical interactions with the mobile device may generate sounds or acoustic emissions that may generate surface charge on one or more of the piezoelectric layers associated with the fingerprint sensor and sensing electrodes that are configured on the mobile device. Acoustically generated piezoelectric signals can in turn be detected in capacitive or ultrasonic detection modes. In some implementations, physical interactions such as pressing, bending, flexing, grasping, or squeezing the mobile device by a user may generate piezoelectric signals and applied forces that are detected and may trigger, initiate, or otherwise interact with one or more applications. that run on the mobile device. For example, grabbing or squeezing the mobile device enclosure with a right-side or left-side grip can be detected to reduce inadvertent odors from unintentional touch detection with devices having large displays and small or non-existent bezels.

[0135] In some implementations, the controller and one or more sensing electrodes may be configured to detect an acoustically generated piezoelectric signal in capacitive sensing mode. Acoustically generated piezoelectric signals may originate from a shunt, friction, acoustic emission, or other physical interaction from a user's finger interacting with the mobile device. For example, an ADC in the capacitive touch module that operates in a capacitive sensing mode can detect and resolve acoustically generated piezoelectric signals from a piezoelectric layer that is coupled to a capacitive sensing electrode and ADC. The amplitude, waveform or signature of the piezoelectric signal may satisfy an acceptance criterion such as a touch detection threshold and allow advancement to an ultrasonic detection mode for detecting an object such as a finger or for imaging a finger. for authentication. In some implementations, the controller and one or more sensing electrodes may be configured to detect and measure acoustically generated piezoelectric signals while operating in the ultrasonic sensing mode. For example, one or more pixel circuits in an ultrasonic sensor array may be retuned and INT configured to detect any acoustically generated signals with an in-pixel peak detector. The detected signals can be timed and read to determine whether the device should be woken up or another function initiated. When operating in ultrasonic detection mode, acoustically generated piezoelectric signals can be detected to initiate a wake-up function or other functions without generating and transmitting an ultrasonic wave that is normally used for ultrasonic imaging.

[0136] In some implementations, finger detection may occur with a combination of passive listening and active imaging. During a finger detection process, detection of acoustically generated piezoelectric signals in a passive listening mode can occur at a nominal sampling rate on the order of 1 kHz. In parallel, an active ultrasonic detection mode for ultrasonic activation detection with launch and detection of ultrasonic waves can occur at a different sampling rate, such as a rate between 1 and 100 Hz. Complete or partial scans can be made during the active detection mode. If either the passive listening mode or the active detection mode (or both) detects the presence of a finger during the finger detection process, a finger verification process may be triggered. During the finger verification process, the finger can be converted into an ultrasonic image with a full scan and a determination made if the detected object is, in fact, a finger. An interrupt signal can be sent to the application processor to wake up the application process and perform a fingerprint authentication process.

[0137] User-induced actions, such as bending, bending, squeezing, or squeezing the mobile device housing or display, may result in piezoelectric signals that can be detected in both capacitive sensing mode and ultrasonic sensing mode from a fingerprint sensor that is attached to the device casing or display. Detection of user-induced actions may result in one or more parts of the mobile device awakening or initiation of another function such as an authentication process or a screen manipulation. Physically pressing a finger on the fingerprint sensor may result in a user-induced applied force or pressure on the piezoelectric layer that generates a piezoelectric signal for detection in capacitive or ultrasonic detection modes and which may also result in one or more parts of the mobile device waking up or starting another function.

[0138] Configurations such as those illustrated in Figures 18, 19, 21 and 22 of an electronic device 505 with a fingerprint sensor 525 positioned behind and coupled to a display 510 such as an LCD or OLED display, the ability to detect a finger touch or a finger lift by measuring a finger capacitance can be reduced. Piezoelectric signals generated from a physical interaction with the display can be detected when operating in capacitive or ultrasonic sensing mode and serve as a first or second step in a wake-up process prior to imaging an ultrasonic finger and authenticating the fingerprint. For example, a shunt, a friction or an acoustic emission from a user-induced action with a finger on the display can be detected through the display. Detection of a user-induced action by detecting an acoustically generated piezoelectric signal may cause other functions to be initiated such as returning to a home screen or illuminating a portion of the display.

[0139] With configurations such as those illustrated in Figures 23 to 23 B of an electronic device 505 having a back cover constructed from a metal or metal alloy such as titanium, aluminum or an aluminum alloy, the ability to detect a capacitance finger through the metal support cover. To determine a finger touch or finger lift event may be limited. Hybrid activation utilizing a piezoelectric signal generated from a physical interaction can be detected when operating in capacitive or ultrasonic sensing mode and serve as a first or second step in a wake-up process prior to imaging an ultrasonic finger and authenticating the fingerprint or perform another function. For example, a shunt, a friction, or an acoustic emission can be detected through the metal support cover from a user-induced action with a finger interacting with the mobile device and the mobile device can respond accordingly.

[0140] Since most piezoelectric materials are pyroelectric in that surface charge is generated in response to a change in temperature, heat from a finger positioned against the metal support cap can generate a heat-induced piezoelectric signal from an ultrasonic fingerprint sensor attached to the metal support cover that can be detected in capacitive or ultrasonic detection mode. The detected heat-induced piezoelectric signal may satisfy an acceptance criterion such as a touch detection threshold and allow advancement to an ultrasonic detection mode for detecting or imaging the finger.

[0141] Using two or more spatially separated sensor pixels from an ultrasonic sensor array in a temporal measurement process may allow determination of the origin of acoustically generated piezoelectric signals or heat-induced piezoelectric signal. For example, a sound or acoustic emission generated by a user interaction with the mobile device such as a tap or tap on the display or back cover may be detected and the direction and distance of the user interaction to the sensor assembly may be determined by comparison of one or more piezoelectric signals acquired at two different times. Subsequent measurements of acoustically generated piezoelectric signals or heat-induced piezoelectric signals may allow determination of one or more finger gestures, such as a tap, double tap, tap, swipe, or press.

[0142] As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single elements. As an example, “at least one of: a, b or c” is intended to cover: a, b, c, a-b, a-c, b-c and a-b-c.

[0143] The various logics, logic blocks, modules, circuits, and algorithm processes described with respect to the implementations described herein may be implemented as electronic hardware, computer software, or combinations of both. The interchangeability of hardware and software has been described generically in terms of functionality and illustrated in the various illustrative components, blocks, modules, circuits and processes described above. Whether such functionality is implemented in hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0144] The hardware and data processing apparatus used to implement the various logics, logic blocks, modules and circuits described in connection with the aspects described herein can be implemented or realized with a general purpose single-chip or multi-chip processor , a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof, designed to perform the functions described here. A general-purpose processor can be a microprocessor or any conventional processor, controller, microcontroller, or state machine. A processor may be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other configuration. In some implementations, specific processes and methods may be performed by circuitry that is specific to a particular function.

[0145] In one or more aspects, the functions described may be implemented in hardware, digital electronic circuitry, computer software, firmware, in the structures presented in this report and their structural equivalents, or in any combination thereof. Implementations of the subject matter described in this specification may be implemented as one or more computer programs, that is, one or more computer program instruction modules, encoded on a computer storage medium for execution by, or to control the operation of, the data processing device.

[0146] If implemented in software, the functions may be stored or transmitted one or more instructions or code on a computer-readable medium, such as a non-transitory medium. The processes of a method or algorithm described herein may be implemented in a processor-executable software module that may reside on a computer-readable medium. Computer readable media include computer storage media and communication media including any medium that can be enabled to transfer a computer program from one place to another. Storage media can be any available media that can be accessed by a computer. By way of example and not limitation, non-transitory media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that may be used to store desired program code in the form of instructions or data structures and which can be accessed by a computer. Also, any connection can appropriately be called a computer-readable medium. Disc and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), flexible disc and Blu-ray disc where discs usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above shall also be included in the scope of computer-readable media. Additionally, the operations of a method or algorithm may reside as one or any combination or algorithm set of codes and instructions on a machine-readable medium and computer-readable medium, which may be embodied in a computer program product.

[0147] Various modifications to the implementations described in this description may be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other implementations without departing from the spirit or scope of this disclosure. Accordingly, the description is not intended to be limited to the implementations presented here, but should be given the broadest scope compatible with the claims, principles and new features described here. The word “exemplary” is used exclusively here, if at all, to mean “serving as an example, case, or illustration.” Any implementation described here as “exemplary” should not necessarily be construed as preferred or advantageous over other implementations.

[0148] Certain features that are described in this specification in the context of separate implementations may also be implemented in combination in a single implementation. Conversely, several features that are described in the context of a single implementation may also be implemented in multiple implementations separately or in any subcombination. Furthermore, although features may be described above, according to the present invention acting in certain combinations and even initially claimed as such, one or more features of a claimed combination may, in some cases, be excluded from the combination, and the combination claimed may be directed to a subcombination or variation of a subcombination.

[0149] Similarly, while the operations are represented in the drawings in a specific order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to obtain results desirable. In certain circumstances, multitasking and parallel processing may be advantageous. Furthermore, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described program components and systems can generally be integrated into a single software product or packaged into multiple software products. Additionally, other implementations are within the scope of the following claims. In some cases, the actions cited in the claims can be performed in a different order and still obtain desirable results.

[0150] It will be understood that unless the features in any of the particular described implementations are expressly identified as incompatible with each other or the surrounding context implies that they are mutually exclusive and not readily combinable in a complementary and/or supportive sense , the entirety of this disclosure considers and anticipates that specific aspects of complementary implementations may be selectively combined to provide one or more comprehensive but slightly different technical solutions. It will therefore be further considered that the above description has been made by way of example only and that modifications may be made in detail within the scope of this disclosure.

Claims (15)

1. System characterized by comprising: a fingerprint sensor (525) having one or more detection electrodes; and a controller configured to switch the fingerprint sensor (525) between a capacitive detection mode and an ultrasonic detection mode and to: provide one or more first drive signals to the one or more detection electrodes when the fingerprint sensor fingerprint sensor (525) is in capacitive sensing mode, and provides one or more second drive signals to the one or more sensing electrodes when the fingerprint sensor (525) is in ultrasonic sensing mode, the one or more second signals triggering signals other than the one or more first triggering signals; wherein the same one or more sensing electrodes are used in both the capacitive sensing mode and the ultrasonic sensing mode. 2. System according to claim 1, characterized by the controller comprising an amplifier configured to: provide the one or more second drive signals in the ultrasonic detection mode, and be in a high impedance state in the capacitive detection mode. 3. The system of claim 1, wherein the controller is configured to switch the fingerprint sensor to the ultrasonic sensing mode based on the fingerprint sensor detecting a touch in the capacitive sensing mode. 4. The system of claim 3, further comprising a mobile device housing the fingerprint sensor, the mobile device configured to wake up from a standby mode in response to the fingerprint sensor detecting touch in the mode. capacitive sensing or ultrasonic sensing mode. 5. The system of claim 3, wherein the controller is further configured to do one or more of the following: provide, to an application processor for performing fingerprint authentication, an interrupt signal representing that a finger corresponding to the touch is detected by the fingerprint sensor in capacitive detection mode, determine a touch detection threshold, the touch detection threshold based, at least in part, on a contact area of a finger in contact with the print sensor fingerprint, the touch detection threshold capable of being adjusted during a fingerprint authentication process, reporting a finger lift event while operating in capacitive sensing mode or ultrasonic sensing mode, determining a temperature corresponding to the print sensor digital, touch sensing in capacitive sensing mode based, at least in part, on temperature. 6. The system of claim 1, wherein the controller comprises a set of circuitry for generating a first buffered drive signal provided to at least one detection electrode of the fingerprint sensor when the fingerprint sensor is in capacitive sensing mode. 7. System according to claim 1, characterized by the fingerprint sensor comprising one or more piezoelectric micromachined ultrasonic transducers, PMUTs, one or more capacitive micromachined ultrasonic transducers, CMUTs, one or more layers of polyvinylidene fluoride, PVDF, or one or more layers of polyvinylidene fluoride-trifluoroethylene, PVDF-TrFE. 8. System according to claim 1, characterized in that the one or more detection electrodes of the fingerprint sensor comprise a first electrode and a second electrode, the first electrode coupled to provide a first signal when the fingerprint sensor is in the capacitive sensing mode, the second electrode coupled to provide a second signal when the fingerprint sensor is in ultrasonic sensing mode, wherein the first electrode and the second electrode are preferably positioned under a cover glass of a mobile device or under a back cover of the mobile device, or wherein the first electrode and the second electrode are positioned under a screen of a display device, the screen of the display device indicating a position of the fingerprint sensor when a finger touch is detected on the capacitive sensing mode or ultrasonic sensing mode, or wherein the first electrode is a touch screen electrode, or wherein at least one of the first electrode or the second electrode is configured to detect a finger movement. 9. System according to claim 1, characterized by the controller being configured to perform one or more of: configuring the one or more detection electrodes in ultrasonic detection mode upon indication of a change in motion or a change in orientation from from an on-device accelerometer or from an on-device gyroscope, adjust a finger detection rate in capacitive detection mode or in ultrasonic detection mode upon indication of a change in motion or a change in orientation from an on-device accelerometer or from an on-device gyroscope, or adjust a touch detection threshold upon indication of a change in motion or a change in orientation from an on-device accelerometer or an on-device gyroscope. 10. System according to claim 1, characterized in that the controller is configured to detect an acoustically generated piezoelectric signal in the capacitive detection mode, the acoustically generated piezoelectric signal originating from a light knock, a friction or an acoustic emission from a finger. 11. Method for operating a fingerprint sensor (525), the method characterized by comprising: operating the fingerprint sensor (525) in a capacitive sensing mode, the fingerprint sensor (525) having one or more electrodes of sensing, wherein a controller is configured to switch the fingerprint sensor (525) between a capacitive sensing mode and an ultrasonic sensing mode and the same one or more sensing electrodes are used in both the capacitive sensing mode and the ultrasonic detection; determining, by the fingerprint sensor (525) operating in the capacitive detection mode, that an object has touched the one or more detection electrodes; switching, with the controller, the fingerprint sensor (525) to operate in the ultrasonic detection mode; and, with the controller, perform one or both of: determining, using the fingerprint sensor (525) in ultrasonic detection mode, whether the object is a finger; and instructing an application processor to authenticate a finger print. 12. The method of claim 11, wherein switching the fingerprint sensor to operate in the ultrasonic detection mode comprises driving an amplifier to provide a drive signal to an electrode of the fingerprint sensor. 13. The method of claim 11, wherein operating the fingerprint sensor in capacitive detection mode comprises controlling an amplifier to operate in a high impedance state. 14. The method of claim 11, wherein instructing the application processor to authenticate the fingerprint comprises asserting an interrupt signal representing that the object is determined to be a finger using the fingerprint sensor in ultrasonic detection mode . 15. Memory characterized by comprising instructions stored therein which, when executed by one or more processors of a controller, cause the one or more processors to carry out the method as defined in any one of claims 11 to 14.