Patent Description:
Electronic devices such as smart phones, tablets, or "Internet of Things" (IoT) devices and appliances can be made more functional by equipping them with sensors to provide convenient ways of inputting information. One example of those sensors is a biometric sensor, such as a finger-print sensor, which allows the electronic device to perform automated authentication of a user without the user manually inputting a password, a username, or other credential information.

A biometric sensor can be implemented based on an ultrasonic sensor system comprising an ultrasonic transmitter and an ultrasonic receiver. The ultrasonic transmitter may send an ultrasonic wave towards a finger. Fingerprint ridges, valleys between adjacent ridges, etc., may reflect the ultrasonic wave with different intensities back towards the ultrasonic sensor. A distribution of reflected signal strengths can be obtained to produce an image of the fingerprint. The image can then be compared with a reference fingerprint image of the user to authenticate the user.

However, an ultrasonic sensor system can be power inefficient, especially when it is integrated with the display screen of an electronic device. Thus, improved ultrasonic sensing techniques that can provide higher power efficiency are desirable.

<CIT> relates to a method for operating a fingerprint sensor comprising a plurality of ultrasonic transducers, a first subset of ultrasonic transducers of the fingerprint sensor are activated, the first subset of ultrasonic transducers for detecting interaction between an object and the fingerprint sensor. Subsequent to detecting interaction between an object and the fingerprint sensor, a second subset of ultrasonic transducers of the fingerprint sensor are activated, the second subset of ultrasonic transducers for determining whether the object is a human finger, wherein the second subset of ultrasonic transducers comprises a greater number of ultrasonic transducers than the first subset of ultrasonic transducers.

<CIT> relates to a mobile terminal capable of fingerprint recognition, and a control method thereof. A mobile terminal according to the present disclosure may include a terminal body, a display unit disposed on a front surface of the body, a sensing unit configured to receive a user's touch input to recognize the user's fingerprint, and a controller configured to display preset screen information on the display unit while the user's touch input is applied to the sensing unit based on the authentication of the recognized user's fingerprint. Another example of a prior art document in which ultrasonic and capacitive sensing are combined is <CIT>.

A method, according to this disclosure, is as set out in claim <NUM>.

An apparatus, according to this disclosure, is as set out in claim <NUM>.

A non-transitory computer readable medium is as set out in claim <NUM>.

Other aspects of the invention are set out in the dependent claims.

Details of one or more implementations of the subject matter described in this specification are set forth in this disclosure and the accompanying drawings. Other features, aspects, and advantages will become apparent from a review of the disclosure. Note that the relative dimensions of the drawings and other diagrams of this disclosure may not be drawn to scale. The sizes, thicknesses, arrangements, materials, etc., shown and described in this disclosure are made only by way of example and should not be construed as limiting.

Aspects of the present disclosure relate to improvements to power efficiency of ultrasonic sensor systems integrated with display screens. Traditionally, the sensor area of an ultrasonic sensor system is separated from the display area of an electronic device. To reduce the footprint and/or to increase the display screen size of the electronic device, an ultrasonic sensor system can be integrated with the display to form part of a touch display interface. The ultrasonic sensor system can transmit ultrasonic waves over the entire display screen area to detect and to image the user's finger. Such an arrangement, however, is often power inefficient, as the user's finger only overlaps with a small portion of display screen and only reflects a small portion of the ultrasonic waves transmitted by the ultrasonic sensor system, while a large quantity of power is wasted in generating and transmitting ultrasonic waves that are not reflected by the user's finger and not involved in the imaging of the user's fingerprint.

According to aspects of the present disclosure, a subset of an array of ultrasonic transducers are used to perform an ultrasonic sensing operation, based on an indication that an object, such as a user's finger, is in proximity to the array of ultrasonic transducers. The indication may correspond, for instance, to the object being within a certain distance from the array of ultrasonic transducers and may be received, for instance, from a capacitive sensor module. One or more ultrasonic transducers within the array but not part of the subset of ultrasonic transducers may be disabled or operated at a reduced power level, thereby reducing the overall energy consumption of the ultrasonic sensor system.

The following description is directed to certain implementations for the purposes of describing the innovative aspects of this disclosure. However, a person having ordinary skill in the art will readily recognize that the teachings herein may be applied in a multitude of different ways. The described implementations may be implemented in any device, apparatus, or system that includes a millimeter band communications capability. In addition, 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 telephones, multimedia Internet enabled cellular telephones, mobile television receivers, wireless devices, smartphones, smart cards, wearable devices such as bracelets, armbands, wristbands, rings, headbands and patches, etc., Bluetooth® devices, personal data assistants (PDAs), wireless electronic mail receivers, hand-held or portable computers, netbooks, notebooks, smart books, tablets, printers, copiers, scanners, facsimile devices, global positioning system (GPS) receivers/navigators, cameras, digital media players (such as MP3 players), camcorders, game consoles, wrist watches, clocks, calculators, television monitors, flat panel displays, electronic reading devices (e.g., e-readers), mobile health devices, computer monitors, auto displays (including odometer and speedometer displays, etc.), cockpit controls and/or displays, steering wheels, camera view displays (such as the display of a rear view camera in a vehicle), electronic photographs, electronic billboards 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, automated teller machines (ATMs), parking meters, packaging (such as in electromechanical systems (EMS) applications including microelectromechanical systems (MEMS) applications, as well as non-EMS applications), aesthetic structures (such as display of images on a piece of jewelry or clothing) and a variety of EMS devices. The teachings herein also may be used in applications such as, but not limited to, electronic switching devices, radio frequency filters, sensors, accelerometers, gyroscopes, motion-sensing devices, magnetometers, inertial components for consumer electronics, parts of consumer electronics products, 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 depicted solely in the Figures, but instead have wide applicability as will be readily apparent to one having ordinary skill in the art.

Details of one or more implementations of the subject matter described in this specification are set forth in this disclosure, which includes the description and claims in this document and the accompanying drawings. Other features, aspects and advantages will become apparent from a review of the disclosure. Note that the relative dimensions of the drawings and other diagrams of this disclosure may not be drawn to scale. The sizes, thicknesses, arrangements, materials, etc., shown and described in this disclosure are made only by way of example and should not be construed as limiting.

The systems, methods and devices of the disclosure each have several innovative aspects, no single one of which is solely responsible for the desirable attributes disclosed herein.

<FIG> illustrates an example ultrasonic sensing system <NUM>. The left diagram of <FIG> illustrates a perspective view of ultrasonic sensing system <NUM>, while the right diagram of <FIG> illustrates a cross-sectional side view of the ultrasonic sensing system. Ultrasonic sensing system <NUM> includes an ultrasonic transducer <NUM> that overlies a substrate <NUM>, both of which underlie a platen (e.g., a "cover plate" or "cover glass") <NUM> to form a stack along the z-axis perpendicular to the plane of platen <NUM> (e.g., x-y plane). Ultrasonic transducer <NUM> may include both an ultrasonic transmitter <NUM> and an ultrasonic receiver <NUM>.

Ultrasonic transmitter <NUM> can be configured to generate and transmit ultrasonic waves towards platen <NUM>, and in the illustrated implementation, towards a human finger portion <NUM> positioned on the upper surface of platen <NUM>. In some examples, ultrasonic transmitter <NUM> can be configured to generate and transmit ultrasonic plane waves towards platen <NUM>. Ultrasonic transmitter <NUM> may include a piezoelectric material to convert electrical signals provided by a controller of the ultrasonic sensing system into a continuous or pulsed sequence of ultrasonic plane waves at a scanning frequency. In some examples, as shown in <FIG>, ultrasonic transmitter <NUM> includes a layer of piezoelectric material such as, for example, polyvinylidene fluoride (PVDF) or a PVDF copolymer such as PVDF-TrFE. In some examples, other piezoelectric materials may be used in the ultrasonic transmitter <NUM> and/or the ultrasonic receiver <NUM>, such as aluminum nitride (AlN) or lead zirconate titanate (PZT). In some implementations, the ultrasonic transmitter <NUM> and/or ultrasonic receiver <NUM> may additionally or alternatively include capacitive ultrasonic devices such as capacitive micro machined ultrasonic transducers (CMUTs) or piezoelectric ultrasonic devices such as piezoelectric micro machined ultrasonic transducers (PMUTs, also referred to as "piezoelectric micromechanical ultrasonic transducers").

In addition, ultrasonic receiver <NUM> can be configured to detect ultrasonic reflections <NUM> resulting from interactions of the ultrasonic waves transmitted by the ultrasonic transmitter <NUM> with ridges <NUM> and valleys <NUM> defining the fingerprint of the finger portion <NUM> being scanned. In some examples, as shown in <FIG> and <FIG>, ultrasonic transmitter <NUM> can be positioned between platen <NUM> and ultrasonic receiver <NUM>, whereas in some examples ultrasonic receiver <NUM> can be positioned between platen <NUM> and ultrasonic receiver <NUM>. In some examples, ultrasonic receiver <NUM> may include a second piezoelectric layer different from the piezoelectric layer of the ultrasonic transmitter <NUM>. For example, the piezoelectric material of the ultrasonic receiver <NUM> may be any suitable piezoelectric material such as, for example, a layer of PVDF or a PVDF-TrFE copolymer. The piezoelectric layer of ultrasonic receiver <NUM> may convert vibrations caused by the ultrasonic reflections into electrical output signals. In some implementations, ultrasonic receiver <NUM> further includes a thin-film transistor (TFT) layer. In some such implementations, the TFT layer may include circuits configured to amplify or buffer the electrical output signals generated by the piezoelectric layer of ultrasonic receiver <NUM>.

Ridges <NUM> and valleys <NUM> can reflect the ultrasonic wave with different intensities back towards the ultrasonic sensor, which can create a distribution of signal strengths of ultrasonic reflections <NUM>. The TFT circuits can generate electrical output signals reflecting the distribution, and the electrical output signals can be used to create an image of the fingerprint represented by ridges <NUM> and valleys <NUM>.

Ultrasonic sensing system <NUM> can be integrated with an electronic device, such as a smart phones, a tablet, etc., to provide an input interface. In some examples, ultrasonic sensing system <NUM> can be configured as an biometric sensor system to collect biometric information, such as fingerprint information, to authenticate a user who seeks to access certain functions of the electronic device. The collection of the fingerprint information can be performed in lieu of (or in addition to) requiring the user to manually input a password or other credential information. For example, referring back to <FIG>, ultrasonic sensing system <NUM> can perform an ultrasonic sensing operation to capture an image of a fingerprint of a user who seeks to access the electronic device. The image can then be compared with a reference fingerprint image to authenticate the user. Upon authenticating the user, the user can then be provided with access to those functions of the electronic device.

To reduce the footprint and/or to increase the display screen size of the electronic device, ultrasonic sensor system <NUM> can be integrated with the display to form a touch display interface. <FIG> illustrates an example of an electronic device <NUM> having a touch display interface <NUM> with an integrated ultrasonic sensor system <NUM>. The left diagram illustrates a top view of electronic device <NUM>, while the right diagram illustrates a perspective view of display interface <NUM>. As shown in <FIG>, touch display interface <NUM> can include a display screen <NUM> which can be part of or include platen <NUM>, and an array of ultrasonic transducers <NUM>, such as ultrasonic transducers 126a and 126b, which is part of ultrasonic sensing system <NUM>. Array of ultrasonic transducers <NUM> can be arranged in a two-dimensional grid below the entirety of display screen <NUM>.

Referring to the right diagram of <FIG>, display screen <NUM>, a layer of display pixels circuit <NUM> and array of ultrasonic transducers <NUM> can be stacked to form touch display interface <NUM>. Display screen <NUM> can transmit content output by display pixels circuit <NUM>. In addition, each ultrasonic transducer of array of ultrasonic transducers <NUM> can transmit an ultrasonic wave, such as ultrasonic wave 130a, 130b, 130c, 130d, 130e, 130f, <NUM>, etc., through display screen <NUM>, such that ultrasonic waves <NUM> are transmitted over the entire display screen area to detect and to image the user's finger. In <FIG>, the finger portion <NUM> having ridges <NUM> and valleys <NUM> is positioned over a region <NUM> of display screen <NUM> that overlaps with one or more ultrasonic transducers <NUM>, which can transmit ultrasonic wave 130b. Finger portion <NUM> can reflect ultrasonic wave 130b back to transducer 126b as reflected wave <NUM>, which can be detected by transducer 126b.

<FIG> illustrates an example application of touch display interface <NUM>. In <FIG>, electronic device <NUM> can be initially in a lock state in which touch display interface <NUM> displays a locked screen showing, for example, the current time and date. A user can put his/her finger at any position on display screen <NUM>, such as region <NUM>. The one or more ultrasonic transducers <NUM> under region <NUM> can detect and image the fingerprint of finger portion <NUM>. Upon authenticating the user based on the fingerprint image, electronic device <NUM> can transition to an active state in which touch display interface <NUM> displays an active screen including icons <NUM> which can be selected by the user to access one or more applications.

The arrangements of <FIG> provide a touch display interface integrated with an ultrasonic sensing system, which can do away with a separate ultrasonic sensing interface and thus can reduce the footprint and/or increase the available display screen size of electronic device <NUM>. But ultrasonic sensing system <NUM> of <FIG> can be power inefficient. Specifically, referring back to <FIG>, finger portion <NUM> only overlaps with a small portion of display screen <NUM> (e.g., region <NUM>) and reflects only a small portion of the ultrasonic waves <NUM> transmitted by array of ultrasonic transducers <NUM> (e.g., ultrasonic wave 130b), while a large quantity of power is wasted in generating and transmitting ultrasonic waves that are not reflected by the user's finger and not involved in the imaging of the user's fingerprint (e.g., ultrasonic waves 130a and 130c-h).

<FIG> and <FIG> illustrates a touch display interface <NUM> that can provide improved power efficiency. As shown in <FIG>, touch display interface <NUM> can include display screen <NUM> which can be part of or include platen <NUM>, and an array of ultrasonic transducers <NUM>. Array of ultrasonic transducers <NUM> can be arranged in a two-dimensional grid that under the entirety of display screen <NUM>. In addition, each ultrasonic transducer of array of ultrasonic transducers <NUM> can be individually addressable and controllable. Specifically, referring to <FIG>, array of ultrasonic transducers <NUM> can include a set of row buses <NUM> (e.g., 230a, 230b, 230c, 230n, etc.) each driven by a row selector <NUM>, and a set of column buses <NUM> (e.g., 240a, 240b, 240c, <NUM>, etc.) each driven by a column selector <NUM>. Each ultrasonic transducer can be coupled with a row bus <NUM> and a column bus <NUM>. Through a combination of row selection signals on row buses <NUM> provided by row selector <NUM> and column selection signals on column buses <NUM> provided by column selector <NUM>, a subset of array of ultrasonic transducers <NUM> can be selected to transmit ultrasonic waves and to detect reflected ultrasonic waves. For example, by transmitting row selection signals on row buses 240b and 240c, and column selection signals on column buses 230b and 230c, a subset of array of ultrasonic transducers <NUM> including ultrasonic transducers 226a-226d can be selected.

The subset of array of ultrasonic transducers <NUM> can be selected to perform a focused detection operation, based on those ultrasonic transducers being located under a region of display screen <NUM> that overlaps with finger portion <NUM>. For example, referring back to <FIG>, only the subset of ultrasonic transducers <NUM> under region <NUM> (the region where finger portion <NUM> overlaps/touches display screen <NUM>) is enabled to transmit ultrasonic wave <NUM> to finger portion <NUM>. In <FIG>, ultrasonic transducers 226a-226d can be enabled as they are under region <NUM>. On the other hand, the rest of ultrasonic transducers <NUM> outside region <NUM> can be either disabled, or otherwise operated at a lower power state than ultrasonic transducers 226a-226d. For example, the transmitter of each of the rest of ultrasonic transducers <NUM> outside region <NUM> can be disabled so as not to transmit an ultrasonic wave, or can be operated to transmit an ultrasonic wave with reduced signal strength.

With the arrangements of <FIG>, only a subset of array of ultrasonic transducers <NUM> is enabled to perform the focused sensing operation. Such arrangements can eliminate, or at least reduce, the power wasted in generating and transmitting ultrasonic waves that are not reflected by the user's finger and not involved in the imaging of the user's fingerprint (e.g., ultrasonic waves 130a and 130c-h in <FIG>). As a result, the power efficiency of the ultrasonic sensing operation can be improved.

<FIG> illustrate example techniques to identify the subset of array of ultrasonic transducers <NUM> to perform the focused sensing operation. As shown in <FIG>, touch display interface <NUM> includes an array of capacitive sensors <NUM> which forms a stack with display screen <NUM>, layer of display pixels circuit <NUM>, and array of ultrasonic transducers <NUM>. Array of capacitive sensors <NUM> can be arranged in a two-dimensional grid below the entirety of display screen <NUM> as well as the entirety of array of ultrasonic transducers <NUM>. Each capacitive sensor <NUM> can measure the capacitance above a region (e.g., on the x-y plane) of display screen <NUM> that overlaps with one or more ultrasonic transducers <NUM>. For example, in <FIG>, capacitor sensor 302f can measure a capacitance over a region <NUM> of display screen <NUM> that overlaps with ultrasonic transducer 226f. In some other examples, each capacitor sensor can a capacitance over a region that covers multiple ultrasonic transducers (e.g., row(s) or column(s) of ultrasonic transducers <NUM>).

As to be described below, depending on a mode of capacitance measurement operation, the measured capacitances of a region can increase or decrease when an object approaches the region. A determination of an object (e.g., finger portion <NUM>) is at proximity of touch display interface <NUM> (e.g., with a threshold distance), as well as a determination of the region of display screen <NUM> that overlaps with the object, can then be made based on a degree of change in the measured capacitances from array of capacitive sensors <NUM>.

Specifically, referring to <FIG>, array of capacitive sensors <NUM> can output a set of capacitance measurements, such as an array of capacitance measurements <NUM>, with each capacitance measurement output by a capacitive sensor of array of capacitive sensors <NUM>. When an object is within a predetermined distance from a region <NUM> of display screen <NUM>, a subset of capacitive sensors <NUM> under region <NUM> can output a capacitance of C1, whereas each of the rest of array of capacitive sensors <NUM> outputs a capacitance of C0. Capacitance C0 can be the initial capacitance measured by the subset of capacitive sensors <NUM> under region <NUM> when the object is outside the threshold distance from touch display interface <NUM>, whereas capacitance C1 can be bigger than or smaller than capacitance C0. A difference between capacitances C0 and C1 can represent a degree of change of the capacitance measured by the subset of capacitive sensors <NUM> under region <NUM>. A determination can be made that an object is within a threshold distance from touch display interface <NUM> can be made based on for example, a difference between capacitances C0 and C1 exceeding a threshold. Moreover, based on the change of capacitances within region <NUM> (between capacitances C0 an C1) exceeding the threshold, a determination can also be made that the object (e.g., finger portion <NUM>) overlaps with region <NUM>, and a subset of array of ultrasonic transducers <NUM> under region <NUM> can be enabled to perform the ultrasonic sensing operation.

<FIG>, <FIG>, and <FIG> illustrate examples of internal components of array of capacitive sensors <NUM>. As shown in <FIG>, array of capacitive sensors <NUM> comprises a first set of electrodes arranged along a first axis (e.g., x-axis) and configured as column electrodes <NUM> (e.g., electrodes 320a, 320b, 320n, etc.), and a second set of electrodes arranged a long a second axis (e.g., y-axis) and configured as row electrodes <NUM> (e.g., electrodes 322a, 322b, <NUM>, etc.). Row electrodes <NUM> can overlie on column electrodes <NUM>, and the two sets of electrodes can be separated by an electrical insulator. Each electrode can form a capacitive sensor. The electrodes can form a two-dimensional grid below the entirety of display screen <NUM>. The intersection points between the row electrodes and the column electrodes on the two-dimensional grid, including intersection points 324a, 324b, 324n (between row electrode 322a and each of column electrodes 320a, 320b, and 320n), intersection points 326a, 326b, 326n (between row electrode 322b and each of column electrodes 320a, 320b, and 320n), and intersection points 328a, 328b, and 328n (between row electrodes <NUM> and each of column electrodes 320a, 320b, and 320n) can define different locations on display screen <NUM>.

In addition, column electrodes <NUM> are connected to transmit circuits <NUM>, whereas row electrodes <NUM> are connected to receive circuits <NUM>. As to be described below, depending on a mode of capacitance measurement operation, transmit circuits <NUM> and receive circuits <NUM> can drive the row electrodes and the column electrodes with different signals to either measure the absolute capacitances of each electrodes, or to measure the mutual capacitances between each row electrode and each column electrode at the intersection points. In both cases, capacitances at different regions of the two-dimensional grid formed by the row and column electrodes can be measured, and a change in the capacitance of a particular region can be detected when an object is in proximity to that region.

<FIG> illustrates an example of a first mode of capacitance measurement operation, in which the absolute capacitances of each electrode is measured. As shown in <FIG>, each row electrode and each column electrode can have an initial capacitance C0 with respect to ground. When an object (e.g., finger portion <NUM>) is in proximity to at a particular electrode, an additional capacitance to ground can be formed between the object and the electrode, which adds to the initial capacitance C0 of that electrode. The added capacitance depends on the distance between the object and the electrode, with a shorter distance leading to a larger added capacitance and vice versa. For example, in <FIG>, finger portion <NUM> is in proximity to row electrode 322b and column electrode 320b. As a result, each electrode can have an increased capacitance of C0+ΔC to ground.

To perform the first mode of capacitance measurement operation, transmit circuits <NUM> can connect the transmit column electrodes to ground, whereas receive circuits <NUM> can connect the row electrodes to ground. A scanning circuit can scan through each row electrode and column electrode sequentially, such as by connecting the electrode to an AC source such as AC sources <NUM> and <NUM>, and measure the amount of current on each electrode, which indicates the capacitance (with respect to ground) of each electrode. In some examples, the scanning circuit may operate in a low power mode and only scans through each row electrode. When finger portion <NUM> approaches one or more electrodes, the capacitances of those electrodes increase, which can be reflected in the increased currents that flow through those electrodes.

Table <NUM> illustrates an example of the scanning result. As shown in table <NUM>, row electrodes Row1 and Row2, as well as column electrodes Column2 andCcolumn3, have measured absolute capacitances C1, while the rest of the electrodes have initial absolute capacitance C0. If the difference between capacitances C0 and C1 exceeds a threshold, which indicate that an object is with a threshold distance from row electrodes Row1 and Row2 and column electrodes Column2 and Column3, a determination can be made that the object is in proximity to a region defined by the intersection points between electrode Row1 and each of column electrodes Column2 and Column3, and between electrode Row2 and each of column electrodes Column2 and Column3. A subset of ultrasonic transducers <NUM> that overlap with that region can then be enabled to perform a ultrasonic sensing operation for the object.

<FIG> illustrates an example of a second mode of capacitance measurement operation, in which the mutual capacitances between each row electrode and each column electrode at the intersection points are measured. In the second mode of capacitance measurement operation, each row electrode and each column electrode can be connected to a voltage source to create an electric field at an intersection point between a row electrode and a column electrode. For example, as shown in <FIG>, row electrode 322b can be connected to a voltage source <NUM> to conduct a first voltage, whereas column electrode 320b can be connected to a voltage source <NUM> to conduct a second voltage, and an electric field <NUM> can be created at intersection point 326b between the first and second voltages. The electric field can also set an initial mutual capacitance C0 between row electrode 322b and column electrode 320b at intersection point 326b. When an object (e.g., finger portion <NUM>) is in proximity to at a particular intersection point, the object can interrupt/disturb the electric field between the electrodes at that intersection point, and the mutual capacitance at that intersection point can become reduced. The reduction in the capacitance also depends on the distance between the object and the electrode, with a shorter distance leading to a larger blockage of electric field and a larger reduction in the capacitance, and vice versa. For example, in <FIG>, finger portion <NUM> is in proximity to intersection point 326b, and the mutual capacitance can become C0-ΔC.

To perform the second mode of capacitance measurement operation, transmit circuits <NUM> can connect the transmit column electrodes to a first set of voltage sources (e.g., voltage source <NUM>), whereas receive circuits <NUM> can connect the row electrodes to a second set of voltage sources (e.g., voltage source <NUM>, which can include ground). A scanning circuit can scan through each pair of intersecting row electrode and column electrode, such as by connecting the electrode to an AC source such as AC sources <NUM> and <NUM> of <FIG>, and measure the amount of current on each electrode. The current can measure the capacitance (with respect to ground) of each electrode, which is half of the mutual capacitance between the electrodes at the intersecting point. When finger portion <NUM> approaches an intersection point, the mutual capacitance of that intersection point decreases, which can be reflected in the increased currents that flow through those electrodes.

Table <NUM> illustrates an example of the scanning result. As shown in table <NUM>, a first intersection point between row0 and column1, and a second intersection point between row0 and column2, can have reduced mutual capacitance C1, whereas the rest of the intersection points have the initial mutual capacitance C0. Based on table <NUM>, a determination can be made that the object is in proximity to the first and second intersection points. A subset of ultrasonic transducers <NUM> that overlap with those intersection points can then be enabled to perform a ultrasonic sensing operation for the object.

The mutual capacitance measurement operation in <FIG> allows measurements of capacitance changes at individual intersection points, which allow detection of multiple objects (e.g., multiple fingers) at multiple discrete regions of the display screen <NUM>. Such arrangements, in turn, allow multiple subsets of ultrasonic transducers <NUM> under multiple discrete regions to be enabled to perform the ultrasonic sensing operation for the multiple objects. But the mutual capacitance measurement operation in <FIG> typically uses more power (e.g., compared with the absolute capacitance measurement operation in <FIG>), as the electrodes are connected to voltage sources to generate the electric fields. Therefore, in a case where only a single object needs to be detected (e.g., a single finger portion to provide a single fingerprint), the absolute capacitance measurement operation in <FIG> can be used to detect the object, and to identify a single subset of ultrasonic transducers <NUM> under a single region of display screen <NUM> to perform the ultrasonic sensing operation.

In some examples, in addition to or in lieu of outputs from array of capacitive sensors <NUM>, a prediction can be made about which region on display screen <NUM> is touched or operated by a user, based on a state of operation of electronic device <NUM>. A subset of array of ultrasonic transducers <NUM> under the predicted region can then be enabled.

<FIG> illustrates example techniques to predict a region on display screen <NUM> is touched or operated by a user. As shown on the left of <FIG>, electronic device <NUM> may include a button <NUM> which, when pressed by a user, can wake up electronic device <NUM> and cause display screen <NUM> to display the lock screen. Upon receiving an indication that button <NUM> is pressed, a prediction can be made that a user touches or operates in a region <NUM> of display screen <NUM>. The prediction can be made based on, for example, a history of the user's operation of electronic device <NUM>, which can indicate that the user frequently touches or gestures at touching region <NUM> when the lock screen is displayed. Based on the prediction, a subset of array of ultrasonic transducers <NUM> under region <NUM> can then be enabled to detect the user's finger portion, while the rest of ultrasonic transducers <NUM> outside region <NUM> can be disabled or operated at a low power state.

In some examples, the prediction can also be made solely based on the content being displayed. For example, as shown on the right of <FIG>, electronic device <NUM> may display a plurality of icons each associated with an application or a specific function of electronic device <NUM>, including icon <NUM>. Each icon is to be activated by the user through touching a region of display screen <NUM> enclosing the icon, such as region <NUM> enclosing icon <NUM>. Based on electronic device <NUM> displaying the plurality of icons, a subset of array of ultrasonic transducers <NUM> under region <NUM> can then be enabled to detect the user's finger portion. In some examples, subsets of array of ultrasonic transducers <NUM> under each region enclosing an icon can be enabled but operated at different power states. The subset of ultrasonic transducers <NUM> under the region surrounding the icon most likely to be touched by the user (e.g., based on the user's usage history, the current time/date, etc.) can be operated at the highest power state.

<FIG> illustrates an example ultrasonic transducer controller <NUM> that can implement the techniques described above. In some examples, ultrasonic transducer controller <NUM> is part of an application processor and is coupled with array of ultrasonic transducer <NUM>. Ultrasonic transducer controller <NUM> includes a transmit control module <NUM> and a receive signal processing module <NUM>. Transmit control module <NUM> can determine a subset of array of ultrasonic transducers <NUM> to be enabled to perform a focused ultrasonic sensing operation of an object. Based on the selection, transmit control module <NUM> can transmit signals <NUM>, which can include row select and column select signals targeted at row selector <NUM> and column selector <NUM>, to enable the selected subset of ultrasonic transducers <NUM> to transmit ultrasonic waves. Receive signal processing module <NUM> can receive signal <NUM> indicative of a distribution of the reflected ultrasonic waves detected by the selected subset of ultrasonic transducers <NUM>. Based on the distribution, an image of the object (e.g., a fingerprint image) can be created.

The ultrasonic transducer controller <NUM> is coupled with a capacitive sensor module <NUM> including array of capacitive sensors <NUM> and a capacitive sensor controller <NUM>, where array of capacitive sensor <NUM> and array of ultrasonic transducers <NUM> are stacked as part of touch display interface <NUM> as shown in <FIG>. Capacitive sensor controller <NUM> can track the capacitances measured by array of capacitive sensors <NUM> and detect that an object is in proximity to array of capacitive sensors <NUM> based on, for example, a change in the capacitance measured by at least one capacitive sensor (e.g., an absolute capacitance of a particular row electrode, an absolute capacitance of a particular column electrode, a mutual capacitance at a particular intersection point between a row electrode and a column electrode, etc.) exceeding a threshold. Based on the detection, capacitive sensor controller <NUM> can transmit an indication <NUM> to ultrasonic transducer controller <NUM>. In some examples, indication <NUM> can be an interrupt.

Upon receiving indication <NUM>, ultrasonic transducer controller <NUM> can transmit a query <NUM> to capacitive sensor controller <NUM> to obtain raw capacitance measurements. The raw capacitance measurements can include, for example, measurements of capacitances of each row and column electrodes, measurements of capacitances of each row electrode if capacitive sensor controller <NUM> operates in a low power mode, a mutual capacitance at each particular intersection points, etc., obtained by array of capacitive sensors, such as the measurement results shown in table <NUM> of <FIG> and in table <NUM> of <FIG>. Based on the raw capacitance measurements, transmit control module <NUM> can determine the subset of ultrasonic transducers <NUM> to be enabled. For example, referring to <FIG>, transmit control module <NUM> can identify the row and column electrodes for which a reduction of the absolute capacitance exceeds a threshold, and determine a region of display screen <NUM> defined by the row and column electrodes. As another example, referring to <FIG>, transmit control module <NUM> can identify the intersection points for which a reduction of the mutual capacitance exceeds a threshold, and determine a region of display screen <NUM> comprising the identified intersection points. In both examples, transmit control module <NUM> can then enable the subset of ultrasonic transducers <NUM> that overlap with that region to perform an ultrasonic sensing operation for the object.

In some examples, ultrasonic transducer controller <NUM> can be coupled with an operation state module <NUM> which tracks a state of operation of electronic device <NUM>. The state of operation can include, for example, a wake-up state of electronic device <NUM>, the content being displayed by electronic device <NUM>. Operation state module <NUM> can transmit an indication <NUM> indicating that a user is about to operate (or operates) display screen <NUM> based on, for example, receiving an indication that a button (e.g., button <NUM> of <FIG>) of the electronic device is pressed and a lock screen is displayed on display screen <NUM>, a plurality of icons is being displayed on display screen <NUM>, etc..

Upon receiving indication <NUM>, transmit control module <NUM> can predict a region of display screen <NUM> the user touches or operates. The prediction can be made based on, for example, a history of the user's operation of electronic device <NUM> (e.g., based on prior raw capacitance measurement results from capacitive sensor module <NUM>), which can indicate that the user frequently touches or gestures at a particular region <NUM> when the lock screen is displayed. The prediction can also be made based on the locations of the icons, each of which is to be activated by the user through touching a region of display screen <NUM> enclosing the icon. Transmit control module <NUM> can then enable the subset of ultrasonic transducers <NUM> under the predicted region to perform the focused ultrasonic sensing operation.

<FIG> illustrates an example method <NUM> of performing an ultrasonic sensing operation. Method <NUM> can be performed by, for example, ultrasonic transducer controller <NUM> of <FIG> in conjunction with other components of electronic device <NUM>, such as display screen <NUM>.

In operation <NUM>, ultrasonic transducer controller <NUM> receives an indication that an object is within a distance from an array of ultrasonic transducers (e.g., array of ultrasonic transducers <NUM>).

Specifically, the indication comes from a capacitive sensor module, such as capacitive sensor module <NUM> including array of capacitive sensors <NUM> and a capacitive sensor controller <NUM>, where array of capacitive sensor <NUM> and array of ultrasonic transducers <NUM> are stacked as part of touch display interface <NUM> as shown in <FIG>. Capacitive sensor controller <NUM> can track the capacitances measured by array of capacitive sensors <NUM> and detect that an object is in proximity to array of capacitive sensors <NUM> based on, for example, a change in the capacitance measured by at least one capacitive sensor exceeding the threshold. The capacitance measured can include, for example, an absolute capacitance of a particular row electrode, an absolute capacitance of a particular column electrode, a mutual capacitance at a particular intersection point between a row electrode and a column electrode, etc., as described in <FIG> and <FIG>. Based on the detection, capacitive sensor controller <NUM> can transmit the indication to ultrasonic transducer controller <NUM>. In some examples, the indication can be an interrupt.

In some examples, the indication can also reflect a state of operation of electronic device <NUM>, such as a wake-up state of electronic device <NUM>, the content being displayed by electronic device <NUM>, etc. The indication can be received from operation state module <NUM> indicating that a user is about to operate (or operates) display screen <NUM> based on, for example, receiving an indication that a button (e.g., button <NUM> of <FIG>) of the electronic device is pressed and a lock screen is displayed on display screen <NUM>, a plurality of icons is being displayed on display screen <NUM>, etc..

In operation <NUM>, ultrasonic transducer controller <NUM>, based on the indication, configures a subset of the array of ultrasonic transducers to perform an ultrasonic sensing operation on the object.

Specifically, in a case where ultrasonic transducer controller <NUM> receives the indication from capacitive sensor module <NUM>, ultrasonic transducer controller <NUM> can transmit a query <NUM> to capacitive sensor controller <NUM> of the capacitive sensor module to obtain raw capacitance measurements <NUM>, which may be sent from capacitive sensor controller <NUM> back to ultrasonic transducer controller <NUM>. The raw capacitance measurements can include, for example, measurements of capacitances of each row and column electrodes, measurements of capacitances of each row electrode if capacitive sensor controller <NUM> operates in a low power mode, a mutual capacitance at each particular intersection points, etc., obtained by array of capacitive sensors, such as the measurement results shown in table <NUM> of <FIG> and in table <NUM> of <FIG>. Based on the raw capacitance measurements, transmit control module <NUM> can determine the subset of ultrasonic transducers <NUM> to be enabled. For example, referring to <FIG>, transmit control module <NUM> can identify the row and column electrodes for which a reduction of the absolute capacitance exceeds a threshold, and determine a region of display screen <NUM> defined by the row and column electrodes. As another example, referring to <FIG>, transmit control module <NUM> can identify the intersection points for which a reduction of the mutual capacitance exceeds a threshold, and determine a region of display screen <NUM> comprising the identified intersection points. In both examples, transmit control module <NUM> can then enable the subset of ultrasonic transducers <NUM> that overlap with that region to perform the ultrasonic sensing operation for the object.

According to certain aspects of the disclosure, a scanning pattern is used to make detection of the object (e.g., the user's touch) a more efficient process. For instance, to the extent that capacitive sensor controller <NUM> scans individual sensors in the array of capacitive sensors <NUM> in sequential fashion, capacitive sensor controller <NUM> may do so according to a scan pattern. The scan pattern may follow a traditional path, such as starting with the first sensor in a row, then the second sensor in the same row, and so on, until the row is complete, and repeating the same procedure for each row in an ordered fashion. In some examples, however, the the scan pattern may follow a different path that takes into account locations that are more likely to be touched by the sensor at any given time. Instead of starting at a location corresponding to, for example, the first row and first column of the array of capacitive sensors <NUM>, the scanning pattern may start at a location that is most likely to be touched by the user.

The scanning pattern may vary depending on specifics of the user interface, icons associated with applications being presented and/or used, etc. In one example, when an electronic device <NUM> is locked, and the likely user touch is a "left swipe" or "right swipe" toward the bottom of the screen (to perform an unlock operation), the scanning pattern may begin in the lower half of the screen. For instance, the scanning pattern may start at the top of the bottom half of the screen. The scannin pattern can then continue row by row toward the bottom of the screen, then continue to the top half of the screen. Such a non-traditional scanning path may be more efficient and faster in detecting a user touch when the electronic device <NUM> is in the locked mode. In another example, the scanning pattern prioritizes locations such as known icon locations where the user is more likely to touch. In yet another example, the scanning pattern prioritizes locations where user control are positioned, such as the location of a "back" button. Such a scanning pattern may be used, for example, by capacitive sensor module <NUM> in generating the indication <NUM> and/or generating the raw capacitance measurements <NUM> which are provided to ultrasonic transducer controller <NUM>. By utilizing a scanning pattern that prioritizes locations more likely to be touched by the user, actual detection of the user's touch may occur sooner in the scanning sequence, which can lead to earlier detection and improvement in the overall efficiency of the ultrasonic sensing operation.

Moreover, in a case where ultrasonic transducer controller <NUM> receives the indication from operation state module <NUM>, upon receiving indication <NUM>, transmit control module <NUM> can predict a region of display screen <NUM> the user touches or operates. The prediction can be made based on, for example, a history of the user's operation of electronic device <NUM> (e.g., based on prior raw capacitance measurement results from capacitive sensor module <NUM>), which can indicate that the user frequently touches or gestures at a particular region <NUM> when the lock screen is displayed. The prediction can also be made based on the locations of the icons, each of which is to be activated by the user through touching a region of display screen <NUM> enclosing the icon. Transmit control module <NUM> can then enable the subset of ultrasonic transducers <NUM> under the predicted region to perform the focused ultrasonic sensing operation.

In operation <NUM>, ultrasonic transducer controller <NUM> receives, from the subset of the array of ultrasonic transducers, an output of the ultrasonic sensing operation. Specifically, referring to <FIG> and <FIG>, ultrasonic sensors of array of ultrasonic transducers <NUM> can receive ultrasonic wave with different intensities reflected by the object (e.g., finger). Receive signal processing module <NUM> can create a distribution of signal strengths of ultrasonic reflections <NUM>.

In operation <NUM>, ultrasonic transducer controller <NUM>, or other components of electronic device <NUM>, performs an action based on the output of the ultrasonic sensing operation. The action may include, for example, generating an image of the finger based on a distribution of signal strengths of the reflected ultrasonic signals, comparing the image with a reference image of a fingerprint to generate a comparison result, and based on the comparison result, allowing access to a function of a device. For example, based on the comparison result, a user who seeks to access certain icons/apps of an electronic device can be authenticated and granted access to the icons/apps.

<FIG> provides a schematic illustration of one embodiment of a computer system <NUM> that can perform various blocks of the methods provided by various embodiments. A computer system as illustrated in <FIG> may be incorporated as part of the previously described computerized devices, such as electronic device <NUM>, etc. It should be noted that <FIG> is meant only to provide a generalized illustration of various components, any or all of which may be utilized as appropriate. <FIG>, therefore, broadly illustrates how individual system elements may be implemented in a relatively separated or relatively more integrated manner.

The computer system <NUM> is shown comprising hardware elements that can be electrically coupled via a bus <NUM> (or may otherwise be in communication, as appropriate). The hardware elements may include one or more processors <NUM>, including without limitation one or more general purpose processors and/or one or more special purpose processors (such as digital signal processing chips, graphics acceleration processors, video decoders, and/or the like); one or more input devices <NUM>, which can include, without limitation, a mouse, a keyboard, remote control, and/or the like; and one or more output devices <NUM>, which can include, without limitation, a display device, a printer, and/or the like. As used herein, a controller can include functionality of a processor (such as processors <NUM>).

The computer system <NUM> may further include (and/or be in communication with) one or more non-transitory storage devices <NUM>, which can comprise, without limitation, local and/or network accessible storage, and/or can include, without limitation, a disk drive, a drive array, an optical storage device, a solid-state storage device, such as a random access memory ("RAM"), and/or a read-only memory ("ROM"), which can be programmable, flash-updateable and/or the like. Such storage devices may be configured to implement any appropriate data stores, including without limitation, various file systems, database structures, and/or the like.

The computer system <NUM> might also include a communications subsystem <NUM>, which can include without limitation a modem, a network card (wireless or wired), an infrared communication device, a wireless communication device, and/or a chipset (such as a Bluetooth™ device, an <NUM> device, a Wi-Fi device, a WiMax device, cellular communication device, GSM, CDMA, WCDMA, LTE, LTE-A, LTE-U, etc.), and/or the like. The communications subsystem <NUM> may permit data to be exchanged with a network (such as the network described below, to name one example), other computer systems, and/or any other devices described herein. In many embodiments, the computer system <NUM> will further comprise a working memory <NUM>, which can include a RAM or ROM device, as described above.

The computer system <NUM> also can comprise software elements, shown as being currently located within the working memory <NUM>, including an operating system <NUM>, device drivers, executable libraries, and/or other code, such as one or more application programs <NUM>, which may comprise computer programs provided by various embodiments, and/or may be designed to implement methods, and/or configure systems, provided by other embodiments, as described herein. Merely by way of example, one or more procedures described with respect to the method(s) discussed above might be implemented as code and/or instructions executable by a computer (and/or a processor within a computer); in an aspect, then, such code and/or instructions can be used to configure and/or adapt a general purpose computer (or other device) to perform one or more operations in accordance with the described methods.

A set of these instructions and/or code might be stored on a non-transitory computer-readable storage medium, such as the non-transitory storage device(s) <NUM> described above. In some cases, the storage medium might be incorporated within a computer system, such as computer system <NUM>. In other embodiments, the storage medium might be separate from a computer system (e.g., a removable medium, such as a compact disc), and/or provided in an installation package, such that the storage medium can be used to program, configure, and/or adapt a general purpose computer with the instructions/code stored thereon. These instructions might take the form of executable code, which is executable by the computer system <NUM> and/or might take the form of source and/or installable code, which, upon compilation and/or installation on the computer system <NUM> (e.g., using any of a variety of generally available compilers, installation programs, compression/decompression utilities, etc.), then takes the form of executable code.

As mentioned above, in one aspect, some embodiments may employ a computer system (such as the computer system <NUM>) to perform methods in accordance with various embodiments of the invention. According to a set of embodiments, some or all of the procedures of such methods are performed by the computer system <NUM> in response to processor <NUM> executing one or more sequences of one or more instructions (which might be incorporated into the operating system <NUM> and/or other code, such as an application program <NUM>) contained in the working memory <NUM>. Such instructions may be read into the working memory <NUM> from another computer-readable medium, such as one or more of the non-transitory storage device(s) <NUM>. Merely by way of example, execution of the sequences of instructions contained in the working memory <NUM> might cause the processor(s) <NUM> to perform one or more procedures of the methods described herein.

The terms "machine-readable medium," "computer-readable storage medium" and "computer-readable medium," as used herein, refer to any medium that participates in providing data that causes a machine to operate in a specific fashion. These mediums may be non-transitory. In an embodiment implemented using the computer system <NUM>, various computer-readable media might be involved in providing instructions/code to processor(s) <NUM> for execution and/or might be used to store and/or carry such instructions/code. In many implementations, a computer-readable medium is a physical and/or tangible storage medium. Such a medium may take the form of a non-volatile media or volatile media. Non-volatile media include, for example, optical and/or magnetic disks, such as the non-transitory storage device(s) <NUM>. Volatile media include, without limitation, dynamic memory, such as the working memory <NUM>.

Common forms of physical and/or tangible computer-readable media include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, or any other magnetic medium, a CD-ROM, any other optical medium, any other physical medium with patterns of marks, a RAM, a PROM, EPROM, a FLASH-EPROM, any other memory chip or cartridge, or any other medium from which a computer can read instructions and/or code.

Various forms of computer-readable media may be involved in carrying one or more sequences of one or more instructions to the processor(s) <NUM> for execution. Merely by way of example, the instructions may initially be carried on a magnetic disk and/or optical disc of a remote computer. A remote computer might load the instructions into its dynamic memory and send the instructions as signals over a transmission medium to be received and/or executed by the computer system <NUM>.

The communications subsystem <NUM> (and/or components thereof) generally will receive signals, and the bus <NUM> then might carry the signals (and/or the data, instructions, etc. carried by the signals) to the working memory <NUM>, from which the processor(s) <NUM> retrieves and executes the instructions.

It should further be understood that the components of computer system <NUM> can be distributed across a network. For example, some processing may be performed in one location using a first processor while other processing may be performed by another processor remote from the first processor. Other components of computer system <NUM> may be similarly distributed. As such, computer system <NUM> may be interpreted as a distributed computing system that performs processing in multiple locations. In some instances, computer system <NUM> may be interpreted as a single computing device, such as a distinct laptop, desktop computer, or the like, depending on the context.

Specific details are given in the description to provide a thorough understanding of example configurations (including implementations). However, configurations may be practiced without these specific details. For example, well-known circuits, processes, algorithms, structures, and techniques have been shown without unnecessary detail to avoid obscuring the configurations. This description provides example configurations only, and does not limit the scope, applicability, or configurations of the claims. Rather, the preceding description of the configurations will provide those skilled in the art with an enabling description for implementing described techniques. Various changes may be made in the function and arrangement of elements without departing from the scope of the disclosure.

Also, configurations may be described as a process which is depicted as a flow diagram or block diagram. Although each may describe the operations as a sequential process, many of the operations can be performed in parallel or concurrently. A process may have additional steps not included in the figure. Furthermore, examples of the methods may be implemented by hardware, software, firmware, middleware, microcode, hardware description languages, or any combination thereof. When implemented in software, firmware, middleware, or microcode, the program code or code segments to perform the necessary tasks may be stored in a non-transitory computer-readable medium such as a storage medium. Processors may perform the described tasks.

Having described several example configurations, various modifications, alternative constructions, and equivalents may be used without departing from the spirit of the disclosure. For example, the above elements may be components of a larger system, wherein other rules may take precedence over or otherwise modify the application of the invention. Also, a number of steps may be undertaken before, during, or after the above elements are considered.

Claim 1:
A method (<NUM>) at an ultrasonic transducer controller (<NUM>), wherein the ultrasonic transducer controller (<NUM>) is coupled with an array of ultrasonic transducers (<NUM>) and a capacitive sensor module (<NUM>) comprising an array of capacitive sensors (<NUM>) comprising a first set of electrodes, configured as column electrodes, arranged along an x-axis and a second set of electrodes, configured as row electrodes, arranged along a y-axis, wherein the capacitive sensors (<NUM>) form a stack along a z-axis with the array of ultrasonic transducers (<NUM>), the stack forming at least part of a touch display interface (<NUM>, <NUM>), the method comprising:
receiving (<NUM>) an indication (<NUM>), from the capacitive sensor module (<NUM>), that an object is within a distance from the array of ultrasonic transducers (<NUM>), wherein the indication is generated based on the capacitive sensor module detecting that the object is within the distance from the array of capacitive sensors (<NUM>);
based on the indication, configuring (<NUM>) a subset of the array of ultrasonic transducers (<NUM>) to perform an ultrasonic sensing operation on the object;
obtaining (<NUM>), from the subset of the array of ultrasonic transducers, an output of the ultrasonic sensing operation; and
performing (<NUM>) an action based on the output of the ultrasonic sensing operation.