OPERATING A TWO-DIMENSIONAL ARRAY OF ULTRASONIC TRANSDUCERS
In a method of operating a two-dimensional array of ultrasonic transducers, a plurality of array positions comprising pluralities of ultrasonic transducers of the two-dimensional array of ultrasonic transducers is defined, the plurality of array positions each comprising a portion of ultrasonic transducers of the two dimensional array of ultrasonic transducers. For each array position of the plurality of array positions, a plurality of ultrasonic transducers associated with the respective array position are activated. The activation includes transmitting ultrasonic signals from a first group of ultrasonic transducers of the plurality of ultrasonic transducers, wherein at least some ultrasonic transducers of the first group of ultrasonic transducers are phase delayed with respect to other ultrasonic transducers of the first group of ultrasonic transducers, the first group of ultrasonic transducers for forming a focused ultrasonic beam. The activation also includes receiving reflected ultrasonic signals at a second group of ultrasonic transducers of the plurality of ultrasonic transducers.
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This application is a continuation of and claims priority to and the benefit of co-pending U.S. patent application Ser. No. 15/266,673, filed on Sep. 15, 2016, entitled “OPERATING A TWO-DIMENSIONAL ARRAY OF ULTRASONIC TRANSDUCERS,” by Apte et al., having Attorney Docket No. IVS-682, and assigned to the assignee of the present application, which is incorporated herein by reference in its entirety.
The patent application with application Ser. No. 15/266,673 claims priority to and the benefit of then co-pending U.S. Patent Provisional Patent Application 62/331,919, filed on May 4, 2016, entitled “PINNED ULTRASONIC TRANSDUCERS,” by Ng et al., having Attorney Docket No. IVS-681.PR, and assigned to the assignee of the present application, which is incorporated herein by reference in its entirety.
The patent application with application Ser. No. 15/266,673 also claims priority to and the benefit of co-pending U.S. Patent Provisional Patent Application 62/334,388, filed on May 10, 2016, entitled “ULTRASONIC TRANSDUCERS SUPPORTING VIRTUAL BLOCK ARRAYS FOR BEAMFORMING,” by Apte, having Attorney Docket No. IVS-682.PR, and assigned to the assignee of the present application, which is incorporated herein by reference in its entirety.
The patent application with application Ser. No. 15/266,673 also claims priority to and the benefit of co-pending U.S. Patent Provisional Patent Application 62/334,390, filed on May 10, 2016, entitled “ULTRASONIC TRANSDUCERS SUPPORTING BEAM-STEERING FOR ARRAY EDGES,” by Apte, having Attorney Docket No. IVS-683.PR, and assigned to the assignee of the present application, which is incorporated herein by reference in its entirety.
BACKGROUNDPiezoelectric materials facilitate conversion between mechanical energy and electrical energy. Moreover, a piezoelectric material can generate an electrical signal when subjected to mechanical stress, and can vibrate when subjected to a varying electrical voltage. Piezoelectric materials are widely utilized in piezoelectric ultrasonic transducers to generate acoustic waves based on an actuation voltage applied to electrodes of the piezoelectric ultrasonic transducer.
The accompanying drawings, which are incorporated in and form a part of the Description of Embodiments, illustrate various embodiments of the subject matter and, together with the Description of Embodiments, serve to explain principles of the subject matter discussed below. Unless specifically noted, the drawings referred to in this Brief Description of Drawings should be understood as not being drawn to scale. Herein, like items are labeled with like item numbers.
The following Description of Embodiments is merely provided by way of example and not of limitation. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding background or in the following Description of Embodiments.
Reference will now be made in detail to various embodiments of the subject matter, examples of which are illustrated in the accompanying drawings. While various embodiments are discussed herein, it will be understood that they are not intended to limit to these embodiments. On the contrary, the presented embodiments are intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope the various embodiments as defined by the appended claims. Furthermore, in this Description of Embodiments, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the present subject matter. However, embodiments may be practiced without these specific details. In other instances, well known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the described embodiments.
NOTATION AND NOMENCLATURESome portions of the detailed descriptions which follow are presented in terms of procedures, logic blocks, processing and other symbolic representations of operations on data within an electrical device. These descriptions and representations are the means used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. In the present application, a procedure, logic block, process, or the like, is conceived to be one or more self-consistent procedures or instructions leading to a desired result. The procedures are those requiring physical manipulations of physical quantities. Usually, although not necessarily, these quantities take the form of acoustic (e.g., ultrasonic) signals capable of being transmitted and received by an electronic device and/or electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated in an electrical device.
It should be borne in mind, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise as apparent from the following discussions, it is appreciated that throughout the description of embodiments, discussions utilizing terms such as “defining,” “activating,” “transmitting,” “receiving,” “sensing,” “generating,” “imaging,” “performing,” or the like, refer to the actions and processes of an electronic device such as an electrical device.
Embodiments described herein may be discussed in the general context of processor-executable instructions residing on some form of non-transitory processor-readable medium, such as program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or distributed as desired in various embodiments.
In the figures, a single block may be described as performing a function or functions; however, in actual practice, the function or functions performed by that block may be performed in a single component or across multiple components, and/or may be performed using hardware, using software, or using a combination of hardware and software. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, logic, circuits, and steps have been described generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure. Also, the example fingerprint sensing system and/or mobile electronic device described herein may include components other than those shown, including well-known components.
Various techniques described herein may be implemented in hardware, software, firmware, or any combination thereof, unless specifically described as being implemented in a specific manner. Any features described as modules or components may also be implemented together in an integrated logic device or separately as discrete but interoperable logic devices. If implemented in software, the techniques may be realized at least in part by a non-transitory processor-readable storage medium comprising instructions that, when executed, perform one or more of the methods described herein. The non-transitory processor-readable data storage medium may form part of a computer program product, which may include packaging materials.
The non-transitory processor-readable storage medium may comprise random access memory (RAM) such as synchronous dynamic random access memory (SDRAM), read only memory (ROM), non-volatile random access memory (NVRAM), electrically erasable programmable read-only memory (EEPROM), FLASH memory, other known storage media, and the like. The techniques additionally, or alternatively, may be realized at least in part by a processor-readable communication medium that carries or communicates code in the form of instructions or data structures and that can be accessed, read, and/or executed by a computer or other processor.
Various embodiments described herein may be executed by one or more processors, such as one or more motion processing units (MPUs), sensor processing units (SPUs), host processor(s) or core(s) thereof, digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), application specific instruction set processors (ASIPs), field programmable gate arrays (FPGAs), a programmable logic controller (PLC), a complex programmable logic device (CPLD), a discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein, or other equivalent integrated or discrete logic circuitry. The term “processor,” as used herein may refer to any of the foregoing structures or any other structure suitable for implementation of the techniques described herein. As it employed in the subject specification, the term “processor” can refer to substantially any computing processing unit or device comprising, but not limited to comprising, single-core processors; single-processors with software multithread execution capability; multi-core processors; multi-core processors with software multithread execution capability; multi-core processors with hardware multithread technology; parallel platforms; and parallel platforms with distributed shared memory. Moreover, processors can exploit nano-scale architectures such as, but not limited to, molecular and quantum-dot based transistors, switches and gates, in order to optimize space usage or enhance performance of user equipment. A processor may also be implemented as a combination of computing processing units.
In addition, in some aspects, the functionality described herein may be provided within dedicated software modules or hardware modules configured as described herein. Also, the techniques could be fully implemented in one or more circuits or logic elements. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of an SPU/MPU and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with an SPU core, MPU core, or any other such configuration.
Overview of DiscussionDiscussion begins with a description of an example piezoelectric micromachined ultrasonic transducer (PMUT), in accordance with various embodiments. Example arrays including PMUT devices are then described. Example operations of example arrays of ultrasonic transducers (e.g., PMUT devices) are then further described.
Embodiments described herein relate to a method of operating a two-dimensional array of ultrasonic transducers. When an ultrasonic transducer, such as a PMUT device, transmits an ultrasonic signal, the ultrasonic signal typically does not transmit as a straight line. Rather, the ultrasonic signal will transmit to a wider area. For instance, when traveling through a transmission medium, the ultrasonic signal will diffract, thus transmitting to a wide area.
Embodiments described herein provide fingerprint sensing system including an array of ultrasonic transducers for sensing the fingerprint. In order to accurately sense a fingerprint, it is desirable to sense a high resolution image of the fingerprint. Using multiple ultrasonic transducers, some of which are time delayed with respect to other ultrasonic transducers, embodiments described herein provide for focusing a transmit beam (e.g., forming a beam) of an ultrasonic signal to a desired point, allowing for high resolution sensing of a fingerprint, or other object. For instance, transmitting an ultrasonic signal from multiple PMUTs, where some PMUTs transmit at a time delay relative to other PMUTs, provides for focusing the ultrasonic beam to a contact point of a fingerprint sensing system (e.g., a top of a platen layer) for sensing a high resolution image of a pixel associated with the transmitting PMUTs.
In accordance with various embodiments, a plurality of array positions comprising pluralities of ultrasonic transducers of the two-dimensional array of ultrasonic transducers is defined, the plurality of array positions each comprising a portion of ultrasonic transducers of the two dimensional array of ultrasonic transducers. For each array position of the plurality of array positions, a plurality of ultrasonic transducers associated with the respective array position are activated. The activation includes transmitting ultrasonic signals from a first group of ultrasonic transducers of the plurality of ultrasonic transducers, wherein at least some ultrasonic transducers of the first group of ultrasonic transducers are phase delayed with respect to other ultrasonic transducers of the first group of ultrasonic transducers, the first group of ultrasonic transducers for forming a focused ultrasonic beam. The activation also includes receiving reflected ultrasonic signals at a second group of ultrasonic transducers of the plurality of ultrasonic transducers.
In some embodiments, the phase delay pattern is symmetric about a focal point of the focused ultrasonic beam of the transmitting ultrasonic transducers. For example, such a phase delay pattern allows for sensing of a pixel at a center of the transmitting ultrasonic transducers and could be used for array positions within the two-dimensional array of ultrasonic transducers.
In other embodiments, the phase delay pattern of the transmitting ultrasonic transducers is asymmetric about a focal point of the focused ultrasonic beam of the transmitting ultrasonic transducers. For example, such a phase delay pattern allows for sensing of a pixel off-center of the transmitting ultrasonic transducers and could be used for array positions adjacent to an edge of the two-dimensional array of ultrasonic transducers. These embodiments may also be referred to as beam steering, as the phase delay pattern steers a focal point of the beam to a position off-center relative to the group of transmitting ultrasonic transducers.
In accordance with various embodiments, for each array position of the plurality of array positions, one pixel is sensed by focusing an ultrasonic beam, and that this pixel can be sensed using a symmetric phase delay pattern or an asymmetric phase delay pattern. In other embodiments, for each array position, multiple pixels can be sensed by focusing an ultrasonic beam to multiple positions relative to the transmitting ultrasonic transducers, using a combination of asymmetric delay patterns. In various embodiments, a symmetric phase delay pattern may also be used to sense a pixel for an array position. In other words, it should be appreciated that for an array position, one or more pixels can be sensed, allowing for increased resolution of the image sensing.
Piezoelectric Micromachined Ultrasonic Transducer (PMUT)Systems and methods disclosed herein, in one or more aspects provide efficient structures for an acoustic transducer (e.g., a piezoelectric actuated transducer or PMUT). One or more embodiments are now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the various embodiments. It may be evident, however, that the various embodiments can be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing the embodiments in additional detail.
As used in this application, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or”. That is, unless specified otherwise, or clear from context, “X employs A or B” is intended to mean any of the natural inclusive permutations. That is, if X employs A; X employs B; or X employs both A and B, then “X employs A or B” is satisfied under any of the foregoing instances. In addition, the articles “a” and “an” as used in this application and the appended claims should generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form. In addition, the word “coupled” is used herein to mean direct or indirect electrical or mechanical coupling. In addition, the word “example” is used herein to mean serving as an example, instance, or illustration.
In one embodiment, both edge support 102 and interior support 104 are attached to a substrate 140. In various embodiments, substrate 140 may include at least one of, and without limitation, silicon or silicon nitride. It should be appreciated that substrate 140 may include electrical wirings and connection, such as aluminum or copper. In one embodiment, substrate 140 includes a CMOS logic wafer bonded to edge support 102 and interior support 104. In one embodiment, the membrane 120 comprises multiple layers. In an example embodiment, the membrane 120 includes lower electrode 106, piezoelectric layer 110, and upper electrode 108, where lower electrode 106 and upper electrode 108 are coupled to opposing sides of piezoelectric layer 110. As shown, lower electrode 106 is coupled to a lower surface of piezoelectric layer 110 and upper electrode 108 is coupled to an upper surface of piezoelectric layer 110. It should be appreciated that, in various embodiments, PMUT device 100 is a microelectromechanical (MEMS) device.
In one embodiment, membrane 120 also includes a mechanical support layer 112 (e.g., stiffening layer) to mechanically stiffen the layers. In various embodiments, mechanical support layer 140 may include at least one of, and without limitation, silicon, silicon oxide, silicon nitride, aluminum, molybdenum, titanium, etc. In one embodiment, PMUT device 100 also includes an acoustic coupling layer 114 above membrane 120 for supporting transmission of acoustic signals. It should be appreciated that acoustic coupling layer can include air, solid liquid, gel-like materials, or other materials for supporting transmission of acoustic signals. In one embodiment, PMUT device 100 also includes platen layer 116 above acoustic coupling layer 114 for containing acoustic coupling layer 114 and providing a contact surface for a finger or other sensed object with PMUT device 100. It should be appreciated that, in various embodiments, acoustic coupling layer 114 provides a contact surface, such that platen layer 116 is optional. Moreover, it should be appreciated that acoustic coupling layer 114 and/or platen layer 116 may be included with or used in conjunction with multiple PMUT devices. For example, an array of PMUT devices may be coupled with a single acoustic coupling layer 114 and/or platen layer 116.
The described PMUT device 100 can be used with almost any electrical device that converts a pressure wave into mechanical vibrations and/or electrical signals. In one aspect, the PMUT device 100 can comprise an acoustic sensing element (e.g., a piezoelectric element) that generates and senses ultrasonic sound waves. An object in a path of the generated sound waves can create a disturbance (e.g., changes in frequency or phase, reflection signal, echoes, etc.) that can then be sensed. The interference can be analyzed to determine physical parameters such as (but not limited to) distance, density and/or speed of the object. As an example, the PMUT device 100 can be utilized in various applications, such as, but not limited to, fingerprint or physiologic sensors suitable for wireless devices, industrial systems, automotive systems, robotics, telecommunications, security, medical devices, etc. For example, the PMUT device 100 can be part of a sensor array comprising a plurality of ultrasonic transducers deposited on a wafer, along with various logic, control and communication electronics. A sensor array may comprise homogenous or identical PMUT devices 100, or a number of different or heterogonous device structures.
In various embodiments, the PMUT device 100 employs a piezoelectric layer 110, comprised of materials such as, but not limited to, Aluminum nitride (AlN), lead zirconate titanate (PZT), quartz, polyvinylidene fluoride (PVDF), and/or zinc oxide, to facilitate both acoustic signal production and sensing. The piezoelectric layer 110 can generate electric charges under mechanical stress and conversely experience a mechanical strain in the presence of an electric field. For example, the piezoelectric layer 110 can sense mechanical vibrations caused by an ultrasonic signal and produce an electrical charge at the frequency (e.g., ultrasonic frequency) of the vibrations. Additionally, the piezoelectric layer 110 can generate an ultrasonic wave by vibrating in an oscillatory fashion that might be at the same frequency (e.g., ultrasonic frequency) as an input current generated by an alternating current (AC) voltage applied across the piezoelectric layer 110. It should be appreciated that the piezoelectric layer 110 can include almost any material (or combination of materials) that exhibits piezoelectric properties, such that the structure of the material does not have a center of symmetry and a tensile or compressive stress applied to the material alters the separation between positive and negative charge sites in a cell causing a polarization at the surface of the material. The polarization is directly proportional to the applied stress and is direction dependent so that compressive and tensile stresses results in electric fields of opposite polarizations.
Further, the PMUT device 100 comprises electrodes 106 and 108 that supply and/or collect the electrical charge to/from the piezoelectric layer 110. It should be appreciated that electrodes 106 and 108 can be continuous and/or patterned electrodes (e.g., in a continuous layer and/or a patterned layer). For example, as illustrated, electrode 106 is a patterned electrode and electrode 108 is a continuous electrode. As an example, electrodes 106 and 108 can be comprised of almost any metal layers, such as, but not limited to, Aluminum (Al)/Titanium (Ti), Molybdenum (Mo), etc., which are coupled with an on opposing sides of the piezoelectric layer 110. In one embodiment, PMUT device also includes a third electrode, as illustrated in
According to an embodiment, the acoustic impedance of acoustic coupling layer 114 is selected to be similar to the acoustic impedance of the platen layer 116, such that the acoustic wave is efficiently propagated to/from the membrane 120 through acoustic coupling layer 114 and platen layer 116. As an example, the platen layer 116 can comprise various materials having an acoustic impedance in the range between 0.8 to 4 MRayl, such as, but not limited to, plastic, resin, rubber, Teflon, epoxy, etc. In another example, the platen layer 116 can comprise various materials having a high acoustic impedance (e.g., an acoustic impendence greater than 10 MRayl), such as, but not limited to, glass, aluminum-based alloys, sapphire, etc. Typically, the platen layer 116 can be selected based on an application of the sensor. For instance, in fingerprinting applications, platen layer 116 can have an acoustic impedance that matches (e.g., exactly or approximately) the acoustic impedance of human skin (e.g., 1.6×106 Rayl). Further, in one aspect, the platen layer 116 can further include a thin layer of anti-scratch material. In various embodiments, the anti-scratch layer of the platen layer 116 is less than the wavelength of the acoustic wave that is to be generated and/or sensed to provide minimum interference during propagation of the acoustic wave. As an example, the anti-scratch layer can comprise various hard and scratch-resistant materials (e.g., having a Mohs hardness of over 7 on the Mohs scale), such as, but not limited to sapphire, glass, MN, Titanium nitride (TiN), Silicon carbide (SiC), diamond, etc. As an example, PMUT device 100 can operate at 20 MHz and accordingly, the wavelength of the acoustic wave propagating through the acoustic coupling layer 114 and platen layer 116 can be 70-150 microns. In this example scenario, insertion loss can be reduced and acoustic wave propagation efficiency can be improved by utilizing an anti-scratch layer having a thickness of 1 micron and the platen layer 116 as a whole having a thickness of 1-2 millimeters. It is noted that the term “anti-scratch material” as used herein relates to a material that is resistant to scratches and/or scratch-proof and provides substantial protection against scratch marks.
In accordance with various embodiments, the PMUT device 100 can include metal layers (e.g., Aluminum (Al)/Titanium (Ti), Molybdenum (Mo), etc.) patterned to form electrode 106 in particular shapes (e.g., ring, circle, square, octagon, hexagon, etc.) that are defined in-plane with the membrane 120. Electrodes can be placed at a maximum strain area of the membrane 120 or placed at close to either or both the surrounding edge support 102 and interior support 104. Furthermore, in one example, electrode 108 can be formed as a continuous layer providing a ground plane in contact with mechanical support layer 112, which can be formed from silicon or other suitable mechanical stiffening material. In still other embodiments, the electrode 106 can be routed along the interior support 104, advantageously reducing parasitic capacitance as compared to routing along the edge support 102.
For example, when actuation voltage is applied to the electrodes, the membrane 120 will deform and move out of plane. The motion then pushes the acoustic coupling layer 114 it is in contact with and an acoustic (ultrasonic) wave is generated. Oftentimes, vacuum is present inside the cavity 130 and therefore damping contributed from the media within the cavity 130 can be ignored. However, the acoustic coupling layer 114 on the other side of the membrane 120 can substantially change the damping of the PMUT device 100. For example, a quality factor greater than 20 can be observed when the PMUT device 100 is operating in air with atmosphere pressure (e.g., acoustic coupling layer 114 is air) and can decrease lower than 2 if the PMUT device 100 is operating in water (e.g., acoustic coupling layer 114 is water).
In operation, during transmission, selected sets of PMUT devices in the two-dimensional array can transmit an acoustic signal (e.g., a short ultrasonic pulse) and during sensing, the set of active PMUT devices in the two-dimensional array can detect an interference of the acoustic signal with an object (in the path of the acoustic wave). The received interference signal (e.g., generated based on reflections, echoes, etc. of the acoustic signal from the object) can then be analyzed. As an example, an image of the object, a distance of the object from the sensing component, a density of the object, a motion of the object, etc., can all be determined based on comparing a frequency and/or phase of the interference signal with a frequency and/or phase of the acoustic signal. Moreover, results generated can be further analyzed or presented to a user via a display device (not shown).
For example, interior supports structures do not have to be centrally located with a PMUT device area, but can be non-centrally positioned within the cavity. As illustrated in
In this example for fingerprinting applications, the human finger 1252 and the processing logic module 1240 can determine, based on a difference in interference of the acoustic signal with valleys and/or ridges of the skin on the finger, an image depicting epi-dermis and/or dermis layers of the finger. Further, the processing logic module 1240 can compare the image with a set of known fingerprint images to facilitate identification and/or authentication. Moreover, in one example, if a match (or substantial match) is found, the identity of user can be verified. In another example, if a match (or substantial match) is found, a command/operation can be performed based on an authorization rights assigned to the identified user. In yet another example, the identified user can be granted access to a physical location and/or network/computer resources (e.g., documents, files, applications, etc.)
In another example, for finger-based applications, the movement of the finger can be used for cursor tracking/movement applications. In such embodiments, a pointer or cursor on a display screen can be moved in response to finger movement. It is noted that processing logic module 1240 can include or be connected to one or more processors configured to confer at least in part the functionality of system 1250. To that end, the one or more processors can execute code instructions stored in memory, for example, volatile memory and/or nonvolatile memory.
Systems and methods disclosed herein, in one or more aspects provide for the operation of a two-dimensional array of ultrasonic transducers (e.g., an array of piezoelectric actuated transducers or PMUTs). One or more embodiments are now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the various embodiments. It may be evident, however, that the various embodiments can be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing the embodiments in additional detail.
As illustrated, ultrasonic transducer system 1400 includes five ultrasonic transducers 1402 including a piezoelectric material and activating electrodes that are covered with a continuous stiffening layer 1404 (e.g., a mechanical support layer). Stiffening layer 1404 contacts acoustic coupling layer 1406, and in turn is covered by a platen layer 1408. In various embodiments, the stiffening layer 1404 can be silicon, and the platen layer 1408 formed from glass, sapphire, or polycarbonate or similar durable plastic. The intermediately positioned acoustic coupling layer 1406 can be formed from a plastic, epoxy, or gel such as polydimethylsiloxane (PDMS) or other material. In one embodiment, the material of acoustic coupling layer 1406 has an acoustic impedance selected to be between the acoustic impedance of layers 1404 and 1408. In one embodiment, the material of acoustic coupling layer 1406 has an acoustic impedance selected to be close the acoustic impedance of platen layer 1408, to reduce unwanted acoustic reflections and improve ultrasonic beam transmission and sensing. However, alternative material stacks to the one shown in
In operation, and as illustrated in
It should be appreciated that an ultrasonic transducer 1402 of ultrasonic transducer system 1400 may be used to transmit and/or receive an ultrasonic signal, and that the illustrated embodiment is a non-limiting example. The received signal (e.g., generated based on reflections, echoes, etc. of the acoustic signal from an object contacting or near the platen layer 1408) can then be analyzed. As an example, an image of the object, a distance of the object from the sensing component, acoustic impedance of the object, a motion of the object, etc., can all be determined based on comparing a frequency, amplitude, phase and/or arrival time of the received signal with a frequency, amplitude, phase and/or transmission time of the transmitted acoustic signal. Moreover, results generated can be further analyzed or presented to a user via a display device (not shown).
In one embodiment, after the activation of ultrasonic transducers 1502 of array position 1530, ultrasonic transducers 1502 of another array position 1532, comprised of columns 1524, 1526, and 1528 of ultrasonic transducers 1502 are triggered in a manner similar to that described in the foregoing description of array position 1530. In one embodiment, ultrasonic transducers 1502 of another array position 1532 are activated after a detection of a reflected ultrasonic signal at column 1522 of array position 1530. It should be appreciated that while movement of the array position by two columns of ultrasonic transducers is illustrated, movement by one, three, or more columns rightward or leftward is contemplated, as is movement by one or more rows, or by movement by both some determined number of rows and columns. In various embodiments, successive array positions can be either overlapping in part, or can be distinct. In some embodiments the size of array positions can be varied. In various embodiments, the number of ultrasonic transducers 1502 of an array position for emitting ultrasonic waves can be larger than the number of ultrasonic transducers 1502 of an array position for ultrasonic reception. In still other embodiments, array positions can be square, rectangular, ellipsoidal, circular, or more complex shapes such as crosses.
Example ultrasonic transducer system 1500 is operable to beamform a line of a high intensity ultrasonic wave centered over column 1522. It should be appreciated that the principles illustrated in
It should be appreciated that different ultrasonic transducers of ultrasonic transducer block 1600 may be activated for receipt of reflected ultrasonic signals. For example, the center 3×3 ultrasonic transducers of ultrasonic transducer block 1600 may be activated to receive the reflected ultrasonic signals. In another example, the ultrasonic transducers used to transmit the ultrasonic signal are also used to receive the reflected ultrasonic signal. In another example, the ultrasonic transducers used to receive the reflected ultrasonic signals include at least one of the ultrasonic transducers also used to transmit the ultrasonic signals.
In
In various embodiments, as an array position approaches an edge of two-dimensional array 2000, only those ultrasonic transducers that are available in two-dimensional array 2000 are activated. In other words, where a beam is being formed at a center of an array position, but the center is near or adjacent an edge of two-dimensional array 2000 such that at least one ultrasonic transducer of a phase delay pattern is not available (as the array position extends over an edge), then only those ultrasonic transducers that are available in two-dimensional array 2000 are activated. In various embodiments, the ultrasonic transducers that are not available (e.g., outside the edge of two-dimensional array 2000) are truncated from the activation pattern. For example, for a 9×9 ultrasonic transducer block, as the center ultrasonic transducer moves towards the edge such that the 9×9 ultrasonic transducer block extends over the edge of the two-dimensional array, rows, columns, or rows and columns (in the instance of corners) of ultrasonic transducers are truncated from the 9×9 ultrasonic transducer block. For instance, a 9×9 ultrasonic transducer block effectively becomes a 5×9 ultrasonic transducer block when the center ultrasonic transducer is along an edge of the two-dimensional array. Similarly, a 9×9 ultrasonic transducer block effectively becomes a 6×9 ultrasonic transducer block when the center ultrasonic transducer is one row or column from an edge of the two-dimensional array. In other embodiments, as an array position approaches an edge of two-dimensional array 2000, the beam is steered by using phase delay patterns that are asymmetric about the focal point, as described below in accordance with
As illustrated, ultrasonic transducer system 2200 includes three ultrasonic transducers 2202 including a piezoelectric material and activating electrodes that are covered with a continuous stiffening layer 2204 (e.g., a mechanical support layer). Stiffening layer 2204 contacts acoustic coupling layer 2206, and in turn is covered by a platen layer 2208. In various embodiments, the stiffening layer 2204 can be silicon, and the platen layer 2208 formed from glass, sapphire, or polycarbonate or similar durable plastic. The intermediately positioned acoustic coupling layer 2206 can be formed from a plastic or gel such as PDMS or other material. In one embodiment, the material of acoustic coupling layer 2206 has an acoustic impedance selected to be between the acoustic impedance of layers 2204 and 2208. In one embodiment, the material of acoustic coupling layer 2206 has an acoustic impedance selected to be close the acoustic impedance of platen layer 2208, to reduce unwanted acoustic reflections and improve ultrasonic beam transmission and sensing. However, alternative material stacks to the one shown in
In operation, and as illustrated in
It should be appreciated that an ultrasonic transducer 2202 of ultrasonic transducer system 2200 may be used to transmit and/or receive an ultrasonic signal, and that the illustrated embodiment is a non-limiting example. The received signal (e.g., generated based on reflections, echoes, etc. of the acoustic signal from an object contacting or near the platen layer 2208) can then be analyzed. As an example, an image of the object, a distance of the object from the sensing component, an acoustic impedance of the object, a motion of the object, etc., can all be determined based on comparing a frequency, amplitude and/or phase of the received interference signal with a frequency, amplitude and/or phase of the transmitted acoustic signal. Moreover, results generated can be further analyzed or presented to a user via a display device (not shown).
In one embodiment, after the activation of ultrasonic transducers 2302 of array position 2330, ultrasonic transducers 2302 of another array position 2332, comprised of columns 2324, 2326, and 2328 of ultrasonic transducers 2302 are activated. In operation, at an initial time, columns 2324 and 2328 of array position 2332 are triggered to emit ultrasonic waves at an initial time. At a second time (e.g., several nanoseconds later), column 2326 of array position 2332 is triggered. The ultrasonic waves interfere with each other, substantially resulting in emission of a high intensity ultrasonic plane wave centered on column 2326. In one embodiment, the ultrasonic transducers 2302 in columns 2324 and 2328 are switched off, while column 2326 is switched from a transmission mode to a reception mode, allowing detection of any reflected signals. In one embodiment, ultrasonic transducers 2302 of another array position 2332 are activated after a detection of a reflected ultrasonic signal at column 2322 of array position 2330. It should be appreciated that while movement of the array position by two columns of ultrasonic transducers is illustrated, movement by one, three, or more columns rightward or leftward is contemplated, as is movement by one or more rows, or by movement by both some determined number of rows and columns. In various embodiments, successive array positions can be either overlapping in part, or can be distinct. In some embodiments the size of array positions can be varied. In various embodiments, the number of ultrasonic transducers 2302 of an array position for emitting ultrasonic waves can be larger than the number of ultrasonic transducers 2302 of an array position for ultrasonic reception. In still other embodiments, array positions can be square, rectangular, ellipsoidal, circular, or more complex shapes such as crosses.
Example ultrasonic transducer system 2300 is operable to beamform a line of a high intensity ultrasonic wave centered over a column of ultrasonic transducers. It should be appreciated that the principles illustrated in
As previously described, it should be appreciated that any type of activation sequence may be used (e.g., side-to-side, top-to-bottom, random, another predetermined order, row and/or column skipping, etc.) Moreover, it should be appreciated that
Moreover, it should be appreciated that in accordance with various embodiments, multiple phase delay patterns for sensing multiple pixels within an array position can be used for an array position. In other words, multiple pixels can be sensed within a single array position, thereby improving the resolution of a sensed image.
With reference to
In one embodiment, as shown at procedure 3012, an activation sequence of the plurality of array positions is defined.
At procedure 3020, for each array position of the plurality of array positions, a plurality of ultrasonic transducers associated with the respective array position are activated. In one embodiment, the plurality of array positions comprises a same amount of ultrasonic transducers having a uniform arrangement. In one embodiment, the activation of the plurality of ultrasonic transducers associated with the respective array position is performed according to the activation sequence.
In one embodiment, the activating a plurality of ultrasonic transducers associated with the respective array position is performed concurrently for at least two non-overlapping array positions of the plurality of array positions. In another embodiment, wherein the activating a plurality of ultrasonic transducers associated with the respective array position is performed consecutively for at least two overlapping array positions of the plurality of array positions offset by one row of ultrasonic transducers. In another embodiment, wherein the activating a plurality of ultrasonic transducers associated with the respective array position is performed consecutively for at least two overlapping array positions of the plurality of array positions offset by one column of ultrasonic transducers.
At procedure 3030, ultrasonic signals are transmitted from a first group of ultrasonic transducers of the plurality of ultrasonic transducers, wherein at least some ultrasonic transducers of the first group of ultrasonic transducers are phase delayed with respect to other ultrasonic transducers of the first group of ultrasonic transducers, the first group of ultrasonic transducers for forming a focused ultrasonic beam.
In one embodiment, a phase delay pattern of the first group of ultrasonic transducers is symmetric about two axes of the first group of ultrasonic transducers, wherein the two axes are orthogonal to each other. In another embodiment, a phase delay pattern of the first group of ultrasonic transducers is asymmetric about two axes of the first group of ultrasonic transducers, wherein the two axes are orthogonal to each other. In another embodiment, a phase delay pattern of the first group of ultrasonic transducers is symmetric about an axis of the first group of ultrasonic transducers. In one embodiment, the axis is orthogonal to an edge of the two-dimensional array of ultrasonic transducers. In one embodiment, the phase delay pattern of the first group of ultrasonic transducers is symmetric about the axis of the first group of ultrasonic transducers for an array position adjacent an edge of the two-dimensional array of ultrasonic transducers. In one embodiment, a phase delay pattern of the first group of ultrasonic transducers comprises at least three distinct timing phases.
At procedure 3040, reflected ultrasonic signals are received at a second group of ultrasonic transducers of the plurality of ultrasonic transducers. In one embodiment, the first group of ultrasonic transducers and the second group of ultrasonic transducers comprise different ultrasonic transducers of each respective array position of the plurality of ultrasonic transducers. In one embodiment, at least one ultrasonic transducer is comprised within both the first group of ultrasonic transducers and the second group of ultrasonic transducers.
With reference to
In one embodiment, as shown at procedure 3060, second reflected ultrasonic signals are received at the second group of ultrasonic transducers of the plurality of ultrasonic transducers, wherein the reflected ultrasonic signals are for sensing a first pixel of an image and the second reflected ultrasonic signals are for sensing a second pixel of the image.
What has been described above includes examples of the subject disclosure. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the subject matter, but it is to be appreciated that many further combinations and permutations of the subject disclosure are possible. Accordingly, the claimed subject matter is intended to embrace all such alterations, modifications, and variations that fall within the spirit and scope of the appended claims.
In particular and in regard to the various functions performed by the above described components, devices, circuits, systems and the like, the terms (including a reference to a “means”) used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (e.g., a functional equivalent), even though not structurally equivalent to the disclosed structure, which performs the function in the herein illustrated exemplary aspects of the claimed subject matter.
The aforementioned systems and components have been described with respect to interaction between several components. It can be appreciated that such systems and components can include those components or specified sub-components, some of the specified components or sub-components, and/or additional components, and according to various permutations and combinations of the foregoing. Sub-components can also be implemented as components communicatively coupled to other components rather than included within parent components (hierarchical). Additionally, it should be noted that one or more components may be combined into a single component providing aggregate functionality or divided into several separate sub-components. Any components described herein may also interact with one or more other components not specifically described herein.
In addition, while a particular feature of the subject innovation may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms “includes,” “including,” “has,” “contains,” variants thereof, and other similar words are used in either the detailed description or the claims, these terms are intended to be inclusive in a manner similar to the term “comprising” as an open transition word without precluding any additional or other elements.
Thus, the embodiments and examples set forth herein were presented in order to best explain various selected embodiments of the present invention and its particular application and to thereby enable those skilled in the art to make and use embodiments of the invention. However, those skilled in the art will recognize that the foregoing description and examples have been presented for the purposes of illustration and example only. The description as set forth is not intended to be exhaustive or to limit the embodiments of the invention to the precise form disclosed.
Claims
1. A method of operating a two-dimensional array of ultrasonic transducers, the method comprising:
- defining a plurality of array positions comprising pluralities of ultrasonic transducers of the two-dimensional array of ultrasonic transducers, the plurality of array positions each comprising a portion of ultrasonic transducers of the two-dimensional array of ultrasonic transducers, wherein the plurality of array positions are for capturing an image over the two-dimensional array of ultrasonic transducers;
- defining an activation sequence of the plurality of array positions, wherein the activation sequence defines movement of the plurality of array positions over the two-dimensional array of ultrasonic transducers for forming a focused ultrasonic beam at different locations over the two-dimensional array of ultrasonic transducers;
- for each array position of the plurality of array positions, activating a plurality of ultrasonic transducers associated with the respective array position for capturing a pixel of the image, the activating comprising: transmitting ultrasonic signals from a first group of ultrasonic transducers of the plurality of ultrasonic transducers, wherein at least some ultrasonic transducers of the first group of ultrasonic transducers are phase delayed with respect to other ultrasonic transducers of the first group of ultrasonic transducers, the first group of ultrasonic transducers for forming a focused ultrasonic beam focused for reflecting off an object in contact with a contact surface of a platen overlying the two-dimensional array of ultrasonic transducers; and receiving reflected ultrasonic signals at a second group of ultrasonic transducers of the plurality of ultrasonic transducers; and
- performing the activating a plurality of ultrasonic transducers associated with the respective array position according to the activation sequence for each array position of the plurality of array positions.
2. The method of claim 1, wherein the ultrasonic transducers are Piezoelectric Micromachined Ultrasonic Transducer (PMUT) devices.
3. The method of claim 1, wherein a phase delay pattern of the first group of ultrasonic transducers is symmetric about two axes of the first group of ultrasonic transducers, wherein the two axes are orthogonal to each other.
4. The method of claim 1, wherein a phase delay pattern of the first group of ultrasonic transducers is asymmetric about two axes of the first group of ultrasonic transducers, wherein the two axes are orthogonal to each other.
5. The method of claim 1, wherein a phase delay pattern of the first group of ultrasonic transducers is symmetric about an axis of the first group of ultrasonic transducers.
6. The method of claim 5, wherein the axis is orthogonal to an edge of the two-dimensional array of ultrasonic transducers.
7. The method of claim 5, wherein the phase delay pattern of the first group of ultrasonic transducers is symmetric about the axis of the first group of ultrasonic transducers for an array position adjacent an edge of the two-dimensional array of ultrasonic transducers.
8. The method of claim 1, wherein a phase delay pattern of the first group of ultrasonic transducers comprises at least three distinct timing phases.
9. The method of claim 1, wherein the plurality of array positions comprise a same amount of ultrasonic transducers having a uniform arrangement.
10. The method of claim 1, wherein the activating a plurality of ultrasonic transducers associated with the respective array position is performed concurrently for at least two non-overlapping array positions of the plurality of array positions.
11. The method of claim 1, wherein the activating a plurality of ultrasonic transducers associated with the respective array position is performed consecutively for at least two overlapping array positions of the plurality of array positions offset by one row of ultrasonic transducers.
12. The method of claim 1, wherein the activating a plurality of ultrasonic transducers associated with the respective array position is performed consecutively for at least two overlapping array positions of the plurality of array positions offset by one column of ultrasonic transducers.
13. The method of claim 1, wherein the object is a finger.
14. The method of claim 1, wherein at least one array position of the plurality of array positions comprises ultrasonic transducers that are not activated.
15. The method of claim 1, wherein the first group of ultrasonic transducers and the second group of ultrasonic transducers comprise different ultrasonic transducers of each respective array position of the plurality of ultrasonic transducers.
16. The method of claim 1, wherein at least one ultrasonic transducer is comprised within both the first group of ultrasonic transducers and the second group of ultrasonic transducers.
17. The method of claim 1, wherein the activating comprises:
- transmitting second ultrasonic signals from the first group of ultrasonic transducers of the plurality of ultrasonic transducers, wherein at least some ultrasonic transducers of the first group of ultrasonic transducers are phase delayed with respect to other ultrasonic transducers of the first group of ultrasonic transducers, wherein a phase delay pattern of the second ultrasonic signals is different than a phase delay pattern of the ultrasonic signals such that the second ultrasonic signals forms the focused ultrasonic beam over a different location of the array position than the ultrasonic signals; and
- receiving second reflected ultrasonic signals at the second group of ultrasonic transducers of the plurality of ultrasonic transducers, wherein the reflected ultrasonic signals are for sensing a first pixel of an image and the second reflected ultrasonic signals are for sensing a second pixel of the image.
18. The method of claim 1, wherein the transmitting ultrasonic signals from a first group of ultrasonic transducers of the plurality of ultrasonic transducers comprises:
- provided an array position of the plurality of array positions extends over an edge of the two-dimensional array, truncating ultrasonic transducers of the first group of ultrasonic transducers from the array position that extend over the edge of the two-dimensional array.
19. A fingerprint sensor device comprising:
- a two-dimensional array of ultrasonic transducers;
- a platen overlying the two-dimensional array of ultrasonic transducers; and
- a processor, wherein the processor is configured to: define a plurality of array positions comprising pluralities of ultrasonic transducers of the two-dimensional array of ultrasonic transducers, the plurality of array positions each comprising a portion of ultrasonic transducers of the two-dimensional array of ultrasonic transducers, wherein the plurality of array positions are for capturing an image over the two-dimensional array of ultrasonic transducers; define an activation sequence of the plurality of array positions, wherein the activation sequence defines movement of the plurality of array positions over the two-dimensional array of ultrasonic transducers for forming a focused ultrasonic beam at different locations over the two-dimensional array of ultrasonic transducers; for each array position of the plurality of array positions, activate a plurality of ultrasonic transducers associated with the respective array position for capturing a pixel of the image, wherein activating the plurality of ultrasonic transducers comprises: transmit ultrasonic signals from a first group of ultrasonic transducers of the plurality of ultrasonic transducers, wherein at least some ultrasonic transducers of the first group of ultrasonic transducers are phase delayed with respect to other ultrasonic transducers of the first group of ultrasonic transducers, the first group of ultrasonic transducers for forming a focused ultrasonic beam for focusing on a fingerprint pattern of a finger in contact with a contact surface of the platen; and receive reflected ultrasonic signals at a second group of ultrasonic transducers of the plurality of ultrasonic transducers; and
- perform the activating a plurality of ultrasonic transducers associated with the respective array position according to the activation sequence for each array position of the plurality of array positions.
20. A non-transitory computer readable storage medium having computer readable program code stored thereon for causing a computer system to perform method of operating a fingerprint sensor comprising a two-dimensional array of ultrasonic transducers, the method comprising:
- defining a plurality of array positions comprising pluralities of ultrasonic transducers of the two-dimensional array of ultrasonic transducers, the plurality of array positions each comprising a portion of ultrasonic transducers of the two-dimensional array of ultrasonic transducers, wherein the plurality of array positions are for capturing an image over the two-dimensional array of ultrasonic transducers;
- defining an activation sequence of the plurality of array positions, wherein the activation sequence defines movement of the plurality of array positions over the two-dimensional array of ultrasonic transducers for forming a focused ultrasonic beam at different locations over the two-dimensional array of ultrasonic transducers;
- for each array position of the plurality of array positions, activating a plurality of ultrasonic transducers associated with the respective array position for capturing a pixel of the image, the activating comprising: transmitting ultrasonic signals from a first group of ultrasonic transducers of the plurality of ultrasonic transducers, wherein at least some ultrasonic transducers of the first group of ultrasonic transducers are phase delayed with respect to other ultrasonic transducers of the first group of ultrasonic transducers, the first group of ultrasonic transducers for forming a focused ultrasonic beam for focusing on a fingerprint pattern of a finger in contact with a contact surface of a platen overlying the two-dimensional array of ultrasonic transducers; and receiving reflected ultrasonic signals at a second group of ultrasonic transducers of the plurality of ultrasonic transducers; and
- performing the activating a plurality of ultrasonic transducers associated with the respective array position according to the activation sequence for each array position of the plurality of array positions.
Type: Application
Filed: Jun 1, 2020
Publication Date: Nov 12, 2020
Applicant: InvenSense, Inc. (San Jose, CA)
Inventors: Nikhil APTE (Palo Alto, CA), Julius Ming-Lin TSAI (San Jose, CA), Michael Julian DANEMAN (Campbell, CA), Renata Melamud BERGER (Palo Alto, CA)
Application Number: 16/889,641