PATENT DOCUMENT

Publication Number: US-12067161-B1
Application Number: US-202117234659-A
Country: US
Kind Code: B1

Title: Ultrasonic transducers for position tracking

Abstract:
Ultrasonic transducers may be used to track the position of an object. For example, eyewear such as a pair of glasses or other head-mounted device may use ultrasonic transducers to track a user&#39;s eye position and gaze direction. To increase positioning accuracy over short-range distances, an array of ultrasonic transducers with different center frequencies may be formed on a common substrate. The closely spaced ultrasonic transducers with relatively small individual bandwidths may be used to simulate a single transducer with a larger bandwidth. Control circuitry may adjust the phases of the transducers in the array to steer the ultrasonic signal beam towards the user&#39;s eye and/or to receive an ultrasonic signal beam from the direction of the user&#39;s eye. The control circuitry may use time delay and/or phase delay measurement techniques to determine a distance and/or direction to the user&#39;s eye using the ultrasonic transducer arrays.

Claims:
What is claimed is: 
     
       1. Eyeglasses configured to be worn by a user, the eyeglasses comprising:
 at least one adjustable lens that aligns with a respective one of the user&#39;s eyes; 
 gaze tracking circuitry that gathers gaze information, wherein the gaze tracking circuitry comprises an array of ultrasonic transducers operating at different center frequencies; and 
 control circuitry that controls the adjustable lens based on the gaze information. 
 
     
     
       2. The eyeglasses defined in  claim 1  wherein the array of ultrasonic transducers is one of multiple arrays of ultrasonic transducers that are distributed around the user&#39;s eyes. 
     
     
       3. The eyeglasses defined in  claim 1  wherein the array of ultrasonic transducers comprises piezoelectric micromachined ultrasonic transducers. 
     
     
       4. The eyeglasses defined in  claim 1  wherein the array of ultrasonic transducers comprises capacitive micromachined ultrasonic transducers. 
     
     
       5. The eyeglasses defined in  claim 1  wherein the array of ultrasonic transducers comprises at least three ultrasonic transducers having respective first, second, and third center frequencies that are different from one another. 
     
     
       6. The eyeglasses defined in  claim 1  wherein the array of ultrasonic transducers comprises a phased array of ultrasonic transducers. 
     
     
       7. The eyeglasses defined in  claim 1  wherein the array of ultrasonic transducers share a common substrate. 
     
     
       8. The eyeglasses defined in  claim 1  wherein the array of ultrasonic transducers comprises at least one set of ultrasonic transducers with the same center frequency that are located adjacent to one another within the array. 
     
     
       9. The eyeglasses defined in  claim 1  wherein the transducers in the array with different center frequencies have different cavity depths in a common substrate. 
     
     
       10. The eyeglasses defined in  claim 1  wherein the transducers in the array with different center frequencies have cavities with different surface features in a common substrate. 
     
     
       11. Gaze tracking circuitry, comprising:
 a first array of ultrasonic transducers on a first substrate, wherein the first array includes at least first and second ultrasonic transducers that operate at respective first and second different frequencies and wherein the first array emits an ultrasonic signal beam towards a user&#39;s eye; 
 a second array of ultrasonic transducers on a second substrate, wherein the second array comprises at least third and fourth ultrasonic transducers that operate respectively at third and fourth different frequencies and wherein the second array detects the ultrasonic signal beam after it reflects from the user&#39;s eye; and 
 control circuitry that gathers sensor data from the first and second arrays of ultrasonic transducers and that determines at least one of a distance and direction to the user&#39;s eye based on the sensor data. 
 
     
     
       12. The gaze tracking circuitry defined in  claim 11  wherein the first array of ultrasonic transducers comprises a phased array of ultrasonic transducers. 
     
     
       13. The gaze tracking circuitry defined in  claim 12  wherein the control circuitry adjusts phases of the ultrasonic transducers in the first array to steer the ultrasonic signal beam towards the user&#39;s eye. 
     
     
       14. The gaze tracking circuitry defined in  claim 13  wherein the second array of ultrasonic transducers comprises a phased array and wherein the control circuitry adjusts phases of the ultrasonic transducers in the second array so that the second array receives the ultrasonic signal beam from a direction of the user&#39;s eye. 
     
     
       15. The gaze tracking circuitry defined in  claim 11  wherein the control circuitry measures at least one of a time delay and a phase delay associated with the ultrasonic signal beam. 
     
     
       16. A sensor, comprising:
 a substrate; 
 an array of micromachined ultrasonic transducers on the substrate, wherein the array comprises at least first, second, and third micromachined ultrasonic transducers with respective first, second, and third different center frequencies; and 
 control circuitry that determines a distance to an object using the array of micromachined ultrasonic transducers. 
 
     
     
       17. The sensor defined in  claim 16  wherein the first micromachined ultrasonic transducer has a bandwidth that is larger than a gap between the first and second center frequencies. 
     
     
       18. The sensor defined in  claim 16  wherein the first micromachined ultrasonic transducer has a bandwidth that is smaller than a gap between the first and second center frequencies. 
     
     
       19. The sensor defined in  claim 16  wherein the control circuitry independently controls the first, second, and third micromachined ultrasonic transducers to emit a combined ultrasonic signal pulse. 
     
     
       20. The sensor defined in  claim 19  wherein the first, second, and third center frequencies are between 500 kHz and 1.25 MHz.

Description:
This application claims the benefit of U.S. provisional patent application No. 63/014,651, filed Apr. 23, 2020, which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD 
     This relates generally to wearable devices, and, more particularly, to wearable devices such as head-mounted devices and other eyewear. 
     BACKGROUND 
     Head-mounted devices and other eyewear may use gaze tracking circuitry to track a user&#39;s gaze. 
     It can be challenging to design gaze tracking circuitry that performs satisfactorily. If care is not taken, the gaze tracking circuitry may produce inaccurate measurements or may exhibit other performance limitations such as excessive power consumption. 
     SUMMARY 
     Ultrasonic transducers may be used to track the position of an object. For example, eyewear such as a pair of glasses or other head-mounted device may use ultrasonic transducers to track a user&#39;s eye position and gaze direction. To increase positioning accuracy over short-range distances, an array of ultrasonic transducers with different center frequencies may be formed on a common substrate. The closely spaced ultrasonic transducers with relatively small individual bandwidths may be used to simulate a single transducer with a larger bandwidth. 
     Control circuitry may adjust the phases and/or amplitudes of the transducers in the array to steer the ultrasonic signal beam towards the user&#39;s eye (and away from direct paths to receiving transducer arrays, if desired) and/or to receive a reflected ultrasonic signal beam from the direction of the user&#39;s eye. The control circuitry may use time delay measurement techniques, phase delay measurement techniques, and/or amplitude measurement techniques to determine a distance and/or direction to the user&#39;s eye using the ultrasonic transducer arrays. 
     The transducer arrays may include piezoelectric micromachined ultrasonic transducers, capacitive micromachined ultrasonic transducers, and/or other suitable type of ultrasonic transducers formed in a common substrate. The transducers may be provided with different center frequencies by forming cavities with different depths, cavities with different diameters, and/or cavities with different surface features. 
     Control circuitry may control each transducer in the array independently of one another, and/or the control circuitry may control subsets of transducers in the array (e.g., subsets with the same center frequency) independently of other sets of transducers in the array. One or more sets of transducers with the same center frequency may be placed adjacent to one another in the array to help disambiguate phase information. The remaining transducers in the array that are not used for phase disambiguation may be spaced farther apart from other transducers of the same center frequency. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a diagram of illustrative system that includes eyeglasses with adjustable lenses and gaze tracking circuitry in accordance with an embodiment. 
         FIG.  2    is a top view of illustrative gaze tracking circuitry in accordance with an embodiment. 
         FIG.  3    is a cross-sectional side view of an illustrative capacitive ultrasonic transducer that may be used in gaze tracking circuitry in accordance with an embodiment. 
         FIG.  4    is a cross-sectional side view of an illustrative piezoelectric ultrasonic transducer that may be used in gaze tracking circuitry in accordance with an embodiment. 
         FIG.  5    is a top view of an illustrative array of ultrasonic transducers in accordance with an embodiment. 
         FIGS.  6    ad  7  are cross-sectional side views of illustrative arrays of ultrasonic transducers with different center frequencies in accordance with an embodiment. 
         FIG.  8    is a graph of illustrative transfer functions of an array of ultrasonic transducers with a relatively dense frequency coverage in accordance with an embodiment. 
         FIG.  9    is a graph of illustrative transfer functions of an array of ultrasonic transducers with a relatively sparse frequency coverage in accordance with an embodiment. 
         FIG.  10    is a side view of an illustrative array of ultrasonic transducers that may be used to determine the angle of arrival of an incoming acoustic wave in accordance with an embodiment. 
         FIG.  11    is a top view of an illustrative array of ultrasonic transducers in which one or more clusters of ultrasonic transducers have the same center frequency for phase disambiguation assistance in accordance with an embodiment. 
         FIG.  12    is a side view of an illustrative phased array of ultrasonic transducers that may be adjusted using control circuitry to direct a beam of signals towards the cornea and sclera of the eyeball in accordance with an embodiment. 
         FIG.  13    is a side view of an illustrative phased array of ultrasonic transducers that may be adjusted using control circuitry to direct a beam of signals towards the cornea of the eyeball in accordance with an embodiment. 
         FIG.  14    is a top view of illustrative gaze tracking circuitry in which signals emitted by a first array of ultrasonic transducers are reflected by a user&#39;s eye and detected by a second array of ultrasonic transducers in accordance with an embodiment. 
         FIG.  15    is a top view of illustrative gaze tracking circuitry in which signals emitted by a first array of ultrasonic transducers are reflected by a user&#39;s eye and detected by multiple arrays of ultrasonic transducers in accordance with an embodiment. 
         FIG.  16    is a top view of illustrative gaze tracking circuitry in which signals emitted by a first array of ultrasonic transducers are reflected by a user&#39;s eye and detected by a second ultrasonic transducer to determine a center location of the user&#39;s cornea in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Ultrasonic transducers may be used to track the position of one or more objects of interest. For example, eyewear such as a pair of glasses or other head-mounted device may use one or more ultrasonic transducers to track a user&#39;s eye position and gaze direction. The ultrasonic transducers may include capacitive micromachined ultrasonic transducers, piezoelectric micromachined transducers, and/or other suitable ultrasonic transducers for emitting and/or detecting acoustic signals. To increase positioning accuracy over short-range distances, multiple ultrasonic transducers with different center frequencies may be arranged in an array. An array of closely spaced ultrasonic transducers with relatively small individual bandwidths may be used to simulate a single transducer with a much larger bandwidth, without sacrificing performance. When the transducers in the array are properly phased, the array may be able to generate an ultrasonic signal pulse with a much shorter pulse length than that which could be produced with a single transducer alone. Being able to generate short ultrasonic signal pulses may be especially beneficial for determining short-range distances and for resolving two objects that are closely spaced together. For example, a phased transducer array may be able to resolve objects that are as close as one wavelength apart or other suitable distance. 
     If desired, the ultrasonic transducers with different center frequencies may be operated independently of one another to independently measure signals at different frequencies. The independently measured signals can then be used to estimate time of flight and path length to the desired level of accuracy. 
     In arrangements where the ultrasonic transducers are used for gaze tracking in a pair of glasses or other eyewear, multiple arrays of ultrasonic transducers may be distributed at different locations around each of the user&#39;s eyes. Each array may include ultrasonic transducers with different center frequencies. One or more of the arrays may emit ultrasonic signals towards the user&#39;s eye. The ultrasonic signals may reflect off of the user&#39;s eye and may be detected by one or more of the other arrays. Control circuitry may gather data from the transducer arrays to determine the user&#39;s eye position and/or gaze direction (e.g., using time delay measurement techniques, phase delay measurement techniques, amplitude measurement techniques, and/or other suitable measurement techniques). 
     An illustrative system having a device with one or more ultrasonic transducers is shown in  FIG.  1   . System  10  may include a head-mounted device such as eyeglasses  14  (sometimes referred to as glasses  14 , head-mounted device  14 , eyewear  14 , etc.). Glasses  14  may include one or more optical systems such as adjustable lens components  22  mounted in a support structure such as support structure  12 . Structure  12  may have the shape of a pair of eyeglasses (e.g., supporting frames), may have the shape of goggles, may form a housing having a helmet shape, or may have other configurations to help in mounting and securing the components of glasses  14  on the head of a user. 
     Adjustable lens components  22  may form lenses that allow a viewer (e.g., a viewer having eyes  16 ) to view external objects such as object  18  in the surrounding environment. Glasses  14  may include one or more adjustable lens components  22 , each aligned with a respective one of a user&#39;s eyes  16 . As an example, lens components  22  may include a left lens  22  aligned with a viewer&#39;s left eye and may include a right lens  22  aligned with a viewer&#39;s right eye. This is, however, merely illustrative. If desired, glasses  14  may include adjustable lens components  22  for a single eye. 
     Adjustable lenses  22  may be corrective lenses that correct for vision defects. For example, eyes  16  may have vision defects such as myopia, hyperopia, presbyopia, astigmatism, higher-order aberrations, and/or other vision defects. Corrective lenses such as lenses  22  may be configured to correct for these vision defects. Lenses  22  may be adjustable to accommodate users with different vision defects and/or to accommodate different focal ranges. For example, lenses  22  may have a first set of optical characteristics for a first user having a first prescription and a second set of optical characteristics for a second user having a second prescription. Glasses  14  may be used purely for vision correction (e.g., glasses  14  may be a pair of spectacles) or glasses  14  may include displays that display virtual reality or augmented reality content (e.g., glasses  14  may be a head-mounted display). In virtual reality or augmented reality systems, adjustable lens components  22  may be used to move content between focal planes from the perspective of the user. Arrangements in which glasses  14  are spectacles that do not include displays are sometimes described herein as an illustrative example. 
     Glasses  14  may include control circuitry  26 . Control circuitry  26  may include processing circuitry such as microprocessors, digital signal processors, microcontrollers, baseband processors, image processors, application-specific integrated circuits with processing circuitry, and/or other processing circuitry and may include random-access memory, read-only memory, flash storage, hard disk storage, and/or other storage (e.g., a non-transitory storage media for storing computer instructions for software that runs on control circuitry  26 ). 
     Glasses  14  may include input-output circuitry such as eye state sensors, range finders disposed to measure the distance to external object  18 , touch sensors, buttons, microphones to gather voice input and other input, sensors, and other devices that gather input (e.g., user input from viewer  16 ) and may include light-emitting diodes, displays, speakers, and other devices for providing output (e.g., output for viewer  16 ). Glasses  14  may, if desired, include wireless circuitry and/or other circuitry to support communications with a computer or other external equipment. 
     Control circuitry  26  may also control the operation of optical elements such as adjustable lens components  22 . Adjustable lens components  22 , which may sometimes be referred to as adjustable lenses, adjustable lens systems, adjustable optical systems, adjustable lens devices, tunable lenses, etc., may include fluid-filled variable lenses, may include Alvarez lenses, and/or may contain electrically adjustable material such as liquid crystal material, volume Bragg gratings, or other electrically modulated material that may be adjusted to produce customized lenses. Each of components  22  may contain an array of electrodes that apply electric fields to portions of a layer of liquid crystal material or other voltage-modulated optical material with an electrically adjustable index of refraction (sometimes referred to as an adjustable lens power or adjustable phase profile). By adjusting the voltages of signals applied to the electrodes, the index of refraction profile of components  22  may be dynamically adjusted. This allows the size, shape, and location of the lenses formed within components  22  to be adjusted. 
     Glasses  14  may include gaze tracking circuitry such as gaze tracking circuitry  20 . Gaze tracking circuitry  20  may include one or more sensors for tracking a user&#39;s eyes  16 . For example, gaze tracking circuitry  20  may include one or more digital image sensors (e.g. visible image sensors and/or infrared image sensors that gather images of the user&#39;s eyes), ultrasonic sensors, light-based sensors such as lidar (light detection and ranging) sensors, and/or other suitable sensors for tracking the location of a user&#39;s eyes. As an example, gaze tracking circuitry  20  may be used by control circuitry  26  to gather eye information such as cornea location, pupil location, gaze direction, and/or other information about the eye(s) of the viewer. The locations of the viewer&#39;s pupils and the locations of the viewer&#39;s pupils relative to specular glints from light sources with known positions or the rest of the viewer&#39;s eyes may be used to determine the locations of the centers of the viewer&#39;s eyes (i.e., the centers of the user&#39;s pupils) and the direction of view (gaze direction) of the viewer&#39;s eyes. If desired, gaze tracking circuitry  20  may also include a wavefront sensor that measures the aberrations of a user&#39;s eyes so that control circuitry  26  can adjust the optical properties of lens component  22  to correct the user-specific aberrations detected by the wavefront sensor. 
     Gaze tracking information may be used as a form of user input, may be used to determine where, within an image, image content resolution should be locally enhanced in a foveated imaging system (e.g., in arrangements where device  14  is a head-mounted display), and/or may be used to determine where, within one or both of lenses  22 , vision correction should be locally enhanced in a foveated lens arrangement. In a foveated lens arrangement, control circuitry  26  may dynamically adjust lens components  22  so that the optical properties of portions of lens components  22  that align with a user&#39;s gaze are different than the optical properties of portions of lens components  22  that are outside of the user&#39;s gaze. For example, portions of lens components  22  that align with a user&#39;s gaze may be optically modulated to produce a first lens power, while the remaining portions of lens components  22  may be left optically unmodulated, may be optically modulated to produce a second lens power magnitude that is less than the first lens power magnitude, and/or may be optically modulated to produce a phase profile that is less spatially varied than the phase profile of portions of lens components  22  within the user&#39;s gaze. Control circuitry  26  may gather eye information from gaze tracking circuitry  20  and may adjust the optical properties of lens components  22  accordingly. 
       FIG.  2    is a top view of glasses  14  showing how gaze tracking circuitry may be used to track a user&#39;s gaze. As shown in  FIG.  2   , gaze tracking circuitry  20  in glasses  14  may include one or more arrays  24  of ultrasonic transducers. Each array  24  may include multiple ultrasonic transducers  38  on a substrate such as substrate  42 . Ultrasonic transducers  38  within each array  24  may have different center frequencies such that, when used together, the array can collectively achieve the positioning accuracy of a wideband ultrasonic transducer without experiencing the reduction in quality factor that would normally result from a single broadband ultrasonic transducer. Arrays  24  may be mounted in support structure  12  and may be distributed at different locations around the user&#39;s eye  16 . There may be any suitable number of arrays  24  in glasses  14  (e.g., one, two, three, four, five, six, ten, fifteen, twenty, more than twenty, less than twenty, etc.), and each array  24  may include any suitable number of transducers  38  (e.g., five, eight, ten, fifteen, twenty, fifty, one hundred, two hundred, less than two hundred, more than two hundred, etc.). 
     During operation, one or more of arrays  24  such as array  24 A may be used to emit ultrasonic signals  32 . The ultrasonic signals  32  may reflect off of a user&#39;s eye  16  (e.g., may reflect off of cornea  30  of the user&#39;s eye  16 ). One or more of arrays  24  such as array  24 B may be used to detect ultrasonic signals  32  after the signals reflect off of the user&#39;s cornea  30 . Using time-of-flight measurement techniques, control circuitry  26  may be used to determine the time that it takes for the emitted signal  32  to reflect back from eye  16 , which may in turn be used to determine the distance to eye  16  (e.g., the distance to the point of specular reflection on cornea  30 ). As eye  16  rotates, control circuitry  26  may continue to monitor changes in distance to the point of specular reflection on the user&#39;s eye. For example, as the user&#39;s eye  16  moves in direction  36 , ultrasonic signals  32 ′ from transducer array  24 A may reflect off of cornea  30 ′ and may be detected by array  24 B. The time-of-flight of signals  32 ′ may be different from the time-of-flight of signals  32 , due to the change in distance to the point of specular reflection of the user&#39;s eye  16 . Control circuitry  26  may monitor these changes in distance to determine the direction of the user&#39;s gaze during the operation of glasses  14 . If desired, the same array  24  may be used to emit and detect signals  32 . Arrangements in which multiple arrays  24  emit signals  32  and/or where multiple arrays  24  detect signals  32  may also be used. The example of  FIG.  2    is merely illustrative. 
     If desired, one or more of arrays  24  may be a phased transducer array. In a phased ultrasonic transducer array, beam steering techniques may be used in which ultrasonic signal phase and/or magnitude for each transducer in array  24  are adjusted to perform beam steering. Beam steering may be used to “illuminate” a particular area of interest with ultrasonic signals  32 . Beam steering may also be used to avoid illuminating certain areas with ultrasonic signals  32  (e.g., to avoid directly illuminating other arrays  24  and/or to avoid illuminating certain parts of the user&#39;s face). For example, a phased ultrasonic transducer array  24  may be configured to emit a concentrated beam of ultrasonic signals  32  that strikes cornea  30  but does not strike the user&#39;s eye brow. This type of beam steering arrangement may help improve gaze tracking accuracy by avoiding detecting significant reflections from surfaces around the user&#39;s eye  16 . 
     The use of time-of-flight based measurement techniques is merely illustrative. If desired, other time-based, amplitude-based, and/or phase-based measurement schemes such as time difference of arrival measurement techniques, angle of arrival measurement techniques, triangulation methods, and/or other suitable measurement techniques may be used to determine a location of the user&#39;s eye  16  using ultrasonic sensor arrays  24 . Arrangements in which other sensors such as visible light cameras, infrared light cameras, and/or proximity sensors (e.g., infrared proximity sensors or other proximity sensors) are used to gather eye location information, glint location information, gaze direction information, pupil shape information, and/or other eye information may also be used. 
       FIGS.  3  and  4    are cross-sectional side views of illustrative ultrasonic transducers of the type that may be included in gaze tracking circuitry  20 . 
     In the example of  FIG.  3   , ultrasonic transducer  38  is a capacitive micromachined ultrasonic transducer. Ultrasonic transducer  38  of  FIG.  3    includes a movable membrane such as membrane  56 , a substrate  50  (e.g., a semiconductor substrate such as a silicon substrate and/or any other suitable type of substrate), and sidewalls  54  that together define a cavity such as cavity  52 . A pair of capacitive electrodes such as first electrode  46  on membrane  56  and second electrode  48  on substrate  50  may be located on opposing sides of cavity  52 . When control circuitry  26  applies an alternating voltage across electrodes  46  and  48 , the resulting electrostatic force causes membrane  56  to oscillate up and down in directions  44  (see, e.g., membrane  56  oscillating between positions P1 and P2 in  FIG.  3   ), thereby generating an acoustic wave having a frequency that corresponds to the frequency at which membrane  56  oscillates. Transducer  38  may also be used to detect ultrasonic waves, if desired. In particular, incident ultrasonic waves may cause membrane  56  to oscillate, which in turn may cause a change in capacitance across electrodes  46  and  48 . Control circuitry  26  may measure this change in capacitance to determine the frequency, amplitude, and/or phase of the incident ultrasonic waves. 
     In the example of  FIG.  4   , ultrasonic transducer  38  is a piezoelectric micromachined ultrasonic transducer. Ultrasonic transducer  38  of  FIG.  4    includes a movable membrane such as membrane  56 , a substrate  50  (e.g., a semiconductor substrate such as a silicon substrate and/or any other suitable type of substrate), and sidewalls  54  that together define a cavity such as cavity  52 . In a piezoelectric transducer arrangement, membrane  56  is formed from or coupled to a piezoelectric material. A pair of electrodes such as first electrode  46  and second electrode  48  may be located on opposing sides of membrane  56 . Control circuitry  26  may apply an alternating voltage across electrodes  46  and  48  which excites the piezoelectric material in membrane  56 , causing membrane  56  to oscillate up and down in directions  44  (see, e.g., membrane  56  oscillating between positions P1 and P2 in  FIG.  4   ), thereby generating an acoustic wave having a frequency that corresponds to the frequency at which membrane  56  oscillates. Transducer  38  of  FIG.  4    may also be used to detect ultrasonic waves, if desired. In particular, incident ultrasonic waves may cause membrane  56  to oscillate, which in turn causes the piezoelectric material to generate charge. Control circuitry  26  may measure a corresponding change in voltage across electrodes  46  and  48  to determine the frequency, amplitude, and/or phase of the incident ultrasonic waves. 
     The examples of  FIGS.  3  and  4    are merely illustrative. If desired, arrays  24  may include other types of ultrasonic transducers and/or may have ultrasonic transducers with different features and/or different structures from the examples of  FIGS.  3  and  4   . For example, a piezoelectric transducer  38  may include more than two electrodes and more than one layer of piezoelectric material, if desired (e.g., transducer  38  may include two layers of piezoelectric material and three layers of electrodes, or may include any other suitable number of piezoelectric layers and electrode layers). 
       FIG.  5    is a top view of an illustrative ultrasonic transducer array that may be used in gaze tracking circuitry  20 . As shown in  FIG.  5   , transducer array  24  may include multiple transducers  38  on substrate  42 . Array  24  may include transducers  38  with different center frequencies. The center frequency of an ultrasonic transducer may refer to the frequency at the center of the frequency range of which the transducer is capable of operating. For example, array  24  may include transducers with two, three, four, five, six, seven, ten, more than ten, or less than ten center frequencies. The center frequencies of transducers  38  may, for example, be between 750 kHz and 1.25 MHz, between 500 kHz and 1.25 MHz, between 700 kHz and 1 MHz, between 800 kHz and 1.2 MHz, between 900 kHz and 1.1 MHz, between 750 kHz and 1.4 MHz. or between any other suitable frequency range. There may be any suitable number (e.g., one, two, three, four, five, more than five, less than five) of transducers  38  in array  24  for a given center frequency. If desired, each transducer  38  may have one or more natural oscillation frequencies that are used for the excitation or detection of ultrasound waves. 
     The bandwidth of each individual transducer  38  may be smaller than the collective bandwidth spanned by all of the transducers  38  in array  24 . The center frequencies of individual transducers  38  may be selected so that the collective bandwidth of the entire array  24  spans some or all of the desired frequency range (e.g., from 750 kHz to 1.25 MHz, from 700 kHz to 1 MHZ, from 800 kHz to 1.2 MHz, from 900 kHz to 1.1 MHz, from 750 kHz to 1.4 MHz, or any other suitable frequency range). The desired frequency range may depend on the range of distances to be measured. For example, to measure distances to objects that are within a few centimeters (such as a user&#39;s eye  16 ), array  24  may span a frequency range of 750 kHz to 1.25 MHz (as an example). 
     Substrate  42  may have any suitable dimensions. For example, lateral dimensions L1 and L2 of substrate  42  may be between 2 mm and 2.5 mm, between 1 mm and 1.5 mm, between 1 mm and 3 mm, between 2 mm and 4 mm, and/or other suitable length. Dimensions L1 and L2 may be equal (so that substrate  42  has a square footprint) or unequal (so that substrate  42  has a rectangular footprint), or the footprint of substrate  42  may have other shapes (e.g., circular, oval, round, triangular, etc.). 
     Transducers  38  may be arranged in an evenly spaced grid of rows and columns on substrate  42 , or may be arranged with any other suitable pattern (e.g., unevenly spaced clusters, a random pattern, a non-grid pattern, etc.). The example of  FIG.  5    in which transducers  38  have a circular shape is merely illustrative. If desired, transducers  38  may be square, rectangular, oval, round, or any other suitable shape. 
     In some arrangements, it may be desirable to maximize the amount of space between transducers  38  that share the same center frequency. Maximizing the spacing between commonly configured transducers  38  in array  24  may increase the accuracy of distance measurements made with array  24 . Different rules regarding placement of the different subsets of transducers  38  on substrate  42  may be implemented to achieve the desired performance from array  24 . As an example, the convex hull of a given set of transducers  38  that share the same center frequency may cover at least 50% of array  24 , may cover at least 80% of array  24 , or may cover other suitable portions of array  24 . As another example, most pairs of transducers  38  that share the same center frequency may be separated by a transducer  38  of a different center frequency. These examples are merely illustrative. In general, transducers  38  may be placed in any suitable arrangement on substrate  42 . 
     Operation of transducers  38  may be controlled by control circuitry  26 . Substrate  42  may include interconnects  40  for conveying signals between transducers  38  and control circuitry  26 . For example, interconnects  40  may be used to convey driving signals from control circuitry  26  to transducers  38  and to convey sensor signals (e.g., sensor signals associated with ultrasonic waves that are detected by transducers  38 ) from transducers  38  to control circuitry  26 . 
     If desired, transducers  38  in array  24  may be independently controlled from one another. For example, the frequency, phase, and pulse shape of the driving signal for a given transducer  38  may be different from other transducers  38  in array  24 . Each individual transducer  38  in array  24  may be independently controlled with different driving signals, or there may be subsets of transducers  38  (e.g., a subset that share the same center frequency or other suitable subset) that are controlled with the same drive signals but that are independently controlled from other subsets of transducers  38 . This is merely illustrative, however. If desired, transducers  38  may not be independently controlled and/or may be controlled with any other suitable driving scheme. 
     In some arrangements, transducers  38  may be driven by off-chip control circuitry. In this type of arrangement, interconnects  40  may include leads, contact pads, solder and/or other conductive elements for conveying signals between array  24  and control circuitry  26  that is separate from array  24 . In other arrangements, substrate  42  may be a multilayer substrate in which transducers  38  are stacked with a control circuitry layer (e.g., an application-specific integrated circuit layer) that includes control circuitry  26 . With this type of integrated control circuitry, interconnects  40  may include metal vias or and/or other conductive elements for conveying signals between transducers  38  and control circuitry  26  that is located in a different layer of substrate  42 . These examples are merely illustrative. If desired, interconnects  42  may include metal vias for conveying signals between different layers of substrate  42  and may also include contact pads for conveying signals between array  24  and external circuitry. 
       FIGS.  6  and  7    are cross-sectional side views of illustrative arrays of ultrasonic transducers with different center frequencies. 
     In the example of  FIG.  6   , array  24  includes transducers with different center frequencies such as transducer  38 - 1  with a first center frequency, transducer  38 - 2  with a second center frequency, and transducer  38 - 3  with a third center frequency. In piezoelectric micromachined ultrasonic transducers, the center frequency is determined at least in part by the dimensions of the cavity. If desired, transducers  38  may be provided with different center frequencies by using cavities  52  with different dimensions (e.g., different depths, different diameters, etc.). In the example of  FIG.  6   , transducers  38 - 1 ,  38 - 2 , and  38 - 3  have cavities  52  with different respective depths D1, D2 and D3 to achieve the desired set of center frequencies. This may be achieved, for example, by forming membranes  56  on a first substrate (e.g., a substrate forming side walls  54 ) and bonding the first substrate to a second substrate (e.g., substrate  50 ) having pads of different heights. Photolithographic techniques (e.g., grayscale lithography) and/or substrate imprinting techniques may be used to create surfaces at different heights on substrate  50 . One or both of substrate  50  and side walls  54  may be formed from semiconductor material such as silicon or may be formed from any other suitable material. 
     In the example of  FIG.  7   , transducers  38 - 1 ,  38 - 2 , and  38 - 3  have cavities  52  with the same depth but with different surface features such as surface features  58  to create the desired acoustic reflection phase at the center frequency. Surface features  58  may, for example, include protrusions  60  separated by recesses  62 . The size, pattern, height, shape, and/or other characteristic of surface features  58  may be varied for different transducers  38  to achieve the desired center frequency. Membranes  56  may be formed on a first substrate such as the substrate forming side walls  54 . In one illustrative arrangement, surface features  58  are formed on the substrate that forms side walls  54  (e.g., by processing the substrate to produce surface features  58  and/or by attaching surface features  58  to the substrate). In another suitable arrangement, surface features  58  are formed on substrate  50  (e.g., by processing substrate  50  to produce surface features  58  and/or by attaching surface features  58  to substrate  50 ), and substrate  50  may be bonded to side walls  54 . 
     The transducers of  FIGS.  6  and  7    are merely illustrative examples of the types of structures that may be used to achieve different center frequencies in a transducer array. If desired, other structures may be used to produce an array of transducers with different center frequencies. For example, instead of varying the cavity depth as in the example of  FIG.  6   , transducers  38  may have uniform cavity depth (e.g., may all have a relatively short cavity depth) but with different lateral cavity dimensions (e.g., different diameters, different lengths and widths, etc.). Arrangements in which both cavity depth and the lateral dimensions of the cavity are varied may also be used. In general, any suitable technique for producing transducers with different center frequencies may be used. 
       FIGS.  8  and  9    are graphs showing illustrative frequency coverage arrangements for an array of ultrasonic transducers (e.g., an array  24  in gaze tracking circuitry  20 ). 
     In the example of  FIG.  8   , each curve  64  correspond to the transfer function (in the frequency domain) of an associated transducer  38  in a given array  24 . Curve  66  corresponds to the overall frequency coverage of the phased array  24  taken as a whole. In this example, the frequency coverage is relatively dense in the sense that the bandwidth B1 of an individual transducer  38  is larger than or comparable to the gap G1 between adjacent center frequencies. The number of transducers  38  with different center frequencies (and thus the number of curves  64  spanning the desired frequency range) may be greater or less than that shown in  FIG.  8   . When array  24  has a relatively dense frequency coverage of the type shown in  FIG.  8   , the entire bandwidth of curve  66  may be used efficiently during operation of array  24 . 
     In the example of  FIG.  9   , each curve  68  corresponds to the transfer function (in the frequency domain) of an associated transducer  38  in a given array  24 . Curve  70  corresponds to the overall frequency coverage of phased array  24  taken as a whole. In this example, the frequency coverage is relatively sparse in the sense that the bandwidth B2 of an individual transducer  38  is smaller than the gap G2 between adjacent center frequencies. The number of transducers  38  with different center frequencies (and thus the number of curves  68  spanning the desired frequency range) may be greater or less than that shown in  FIG.  9   . When array  24  has a relatively sparse frequency coverage of the type shown in  FIG.  9   , certain portions of the overall bandwidth of curve  70  (e.g., discrete portions centering around the individual center frequencies of transducers  38 ) may be used more efficiently than other portions during operation of array  24 . 
     The examples of  FIGS.  8  and  9    are merely illustrative. If desired, the frequency coverage of arrays  24  may be denser than that shown in  FIG.  8   , may be sparser than that shown in  FIG.  9   , or may have a frequency coverage that is sparser than that of  FIG.  8    but denser than that of  FIG.  9   . In general, measurements from an array with relatively dense frequency coverage may have a greater signal-to-noise ratio than measurements from an array with relatively sparse frequency coverage. 
       FIG.  10    is a schematic diagram showing how angle of arrival (sometimes referred to as direction of arrival) measurement techniques may be used to determine the angle of arrival of incident ultrasonic signals. As shown in  FIG.  10   , array  24  may include multiple transducers  38  (e.g., a first transducer  38 - 1  and a second transducer  38 - 2 ). Transducers  38 - 1  and  38 - 2  may each receive an ultrasonic signal  32  after it reflects off of the user&#39;s eye  16  ( FIG.  2   ). Transducers  38 - 1  and  38 - 2  may be laterally separated by a distance A1, where transducer  38 - 1  is farther away from the user&#39;s eye than transducer  38 - 2  (in the example of  FIG.  10   ). Therefore, ultrasonic signal  32  travels a greater distance to reach transducer  38 - 1  than it does to reach transducer  38 - 2 . The additional distance between the user&#39;s eye and transducer  38 - 1  is shown in  FIG.  10    as distance A2.  FIG.  10    also shows angles X and Y (where X+Y=90°). 
     Distance A2 may be determined as a function of angle Y or angle X (e.g., A2=A1 sin(X) or A2=A1 cos(Y)). Distance A2 may also be determined as a function of the phase difference between the signal received by transducer  38 - 1  and the signal received by transducer  38 - 2  (e.g., A2=(Δϕλ)/(2π), where Δϕ is the phase difference between the signal received by transducer  38 - 1  and the signal received by transducer  38 - 2  and λ is the wavelength of the received signal  32 ). Control circuitry  26  may include phase measurement circuitry coupled to each transducer  38  to measure the phase of the received signals and identify a difference in the phases (Δφ). The two equations for A2 may be set equal to each other (e.g., A1 sin(X)=(Δφλ)/(2π)) and rearranged to solve for angle X (e.g., X=sin −1 ((Δφλ)/(2πA1)) or may be rearranged to solve for angle Y. As such, the angle of arrival may be determined (e.g., by control circuitry  26 ) based on the known (predetermined) distance between transducer  38 - 1  and transducer  38 - 2 , the detected (measured) phase difference between the signal received by transducer  38 - 1  and the signal received by transducer  38 - 2 , and the known wavelength or frequency of the received signals  32 . 
     Because phase measurements are restricted to an interval between negative pi and positive pi, phase wrapping may occur which can, if care is not taken, lead to ambiguous phase difference measurements. Phase disambiguation may be achieved by performing non-uniform sampling and/or by clustering certain transducers together within array  24 . This type of arrangement is illustrated in  FIG.  11   . 
     As shown in  FIG.  11   , some transducers  38  with the same center frequency may be placed adjacent to one another within array  24 . For example, two, three or more transducers  38 A may have the same center frequency and may be clustered together within array  24 . If desired, one or more additional groups of transducers with the same center frequency such as transducers  38 B may be clustered together within array  24  (the center frequency of transducers  38 B and other groups of transducers used for phase disambiguation may be the same or different than the center frequency of transducers  38 A). The close spacing of transducers with the same center frequency (e.g., transducers  38 A, transducers  38 B, and any other clusters of transducers used for phase disambiguation) helps disambiguate phase information by ensuring that the signals detected by transducers  38 A occur close enough in time so that the true phase delay of an incoming signal can be determined. The remaining transducers  38  in array  24  that are not used for phase disambiguation may be spaced farther apart, as discussed in connection with  FIG.  5   . The example of  FIG.  11    is merely illustrative, however. If desired, array  24  may not include any clusters of transducers with the same frequency. 
     The use of multiple transducers  38  in phased transducer array  24  allows beam steering arrangements to be implemented by controlling the relative phases and magnitudes (amplitudes) of the ultrasonic signals conveyed by the transducers. Control circuitry  26  may, for example, include phase shifter circuits and/or circuitry for adjusting the magnitude of the ultrasonic signals. The circuitry within control circuitry  26  that controls the phase and/or magnitude of drive signals for arrays  24  may sometimes be referred to as beam steering circuitry (e.g., beam steering circuitry that steers the beam of ultrasonic signals transmitted and/or received by phased transducer array  24 ). 
     Control circuitry  26  may adjust the relative phases and/or magnitudes of the transmitted signals that are provided to each transducer  38  in phased transducer array  24  and may adjust the relative phases and/or magnitudes of the received signals that are received by phased transducer array  24 . Control circuitry  26  may, if desired, include phase detection circuitry for detecting the phases of the received signals that are received by phased transducer array  24 . The term “beam” or “signal beam” may be used herein to refer to ultrasonic signals that are transmitted and/or received by phased transducer array  24  in a particular direction. The signal beam may exhibit a peak gain that is oriented in a particular pointing direction at a corresponding pointing angle (e.g., based on constructive and destructive interference from the combination of signals from each transducer in the phased transducer array). The term “transmit beam” may sometimes be used herein to refer to ultrasonic signals that are transmitted in a particular direction whereas the term “receive beam” may sometimes be used herein to refer to ultrasonic signals that are received from a particular direction. 
     If, for example, control circuitry  26  provides control signals to transducers  38  to emit ultrasonic signals  32  having a first set of phases and/or magnitudes, the transmitted signals  32  may form a transmit beam that illuminates (i.e., covers) both the cornea  30  and sclera  28  of the user&#39;s eye  16 , as shown in the example of  FIG.  12   . If control circuitry  26  provides control signals to transducers  38  to emit ultrasonic signals  32  having a second set of phases and/or magnitudes, the transmitted signals may form a transmit beam that is concentrated on the cornea  30  and not the sclera  28  of eye  16 , as shown in the example of  FIG.  13   . 
     Control circuitry  26  may also operate array  24  to receive signals from a given range of angles. This may be achieved by adjusting the phase and magnitude of transducers  38  so that ultrasonic signals  32  are received from a particular direction. In other arrangements, this may be achieved post-measurement by changing the gain of signals received from a given region to amplify those signals relative to signals received from other regions. 
     If desired, control circuitry  26  may actively adjust control signals for transducers  38  in real time to steer the transmit or receive beam in different desired directions over time. For example, gaze tracking circuitry  20  may include a camera that captures images of the user&#39;s eye, which in turn may be used to determine the location of a glint on the user&#39;s eye. Control circuitry  26  may control arrays  24  based on eye information gathered with the camera so that beam shaping and beam steering can be performed accordingly (e.g., so that signals  32  are steered towards the location of the glint on the eye and/or received from the location of the glint on the eye). If desired, the ultrasonic signal beam may also be steered away from other arrays  24  (e.g., to avoid a scenario in which a receiving array  24  detects a signal that travels directly to the receiving array  24  from a transmitting array  24  without reflecting off the user). 
     During operation, control circuitry  26  may operate one or more arrays  24  as a transmitting array and one or more arrays  24  as a receiving array. For example, control circuitry  26  may control the phases of transducers  38  in a first array  24  (e.g., a transmitting array) to transmit a short pulse towards the user&#39;s eye and may control the phases of transducers  38  in a second array  24  (e.g., a receiving array) in a similar manner (e.g., such that the receiving array would generate the same short pulse if used for transmission). Control circuitry  26  may also, if desired, control the phases of the transmitting array  24  and the receiving array  24  to direct the ultrasonic signal beam to (or receive the ultrasonic signal beam from) an area of interest and thereby limit detected reflections from other areas. Active phasing may be achieved digitally or in analog. In digital phasing arrangements, control circuitry  26  may use a system clock to shift the time and phase of the driving signal to transducers  38 . If desired, each transducer  38  may have an associated analog to digital converter circuit and phasing can be achieved computationally post-measurement. 
     Control circuitry  26  may, if desired, measure the actual resonance frequency of transducers  38  and may adjust drive signals for transducers  38  to compensate for any detuning that may occur in transducers  38  (e.g., detuning that may occur as a result of manufacturing effects or environmental conditions). This is merely illustrative. If desired, control circuitry  26  may not calculate or compensate for resonance frequency errors. 
     If desired, control circuitry  26  may phase the entire array  24  of transducers  38 , combining all of the different center frequencies to form a short ultrasonic signal pulse. In other arrangements, control circuitry  26  may phase only transducers  38  in array  24  with the same center frequency. For example, each set of transducers  38  with the same center frequency in array  24  may be phased to produce an ultrasonic signal that illuminates the desired area and/or to receive an ultrasonic signal beam from a known range of angles. Control circuitry  26  may determine the phase and/or amplitude of the received signal from each set of phased transducers  38  with the same center frequency in array  24 . Based on the phase and/or amplitude of the received signal at the different frequencies covered by array  24 , control circuitry  26  may determine the time delay and/or phase delay of the emitted signal (and thus the location of the user&#39;s eye). 
       FIG.  14    is a top view of illustrative gaze tracking circuitry  20 . In the example of  FIG.  14   , only two arrays  24  are shown, but there may be additional arrays  24  surrounding eye  16 , if desired. During operation, control circuitry  26  may configure array  24 T to be a transmitting array and array  24 R to be a receiving array. Array  24 T may include transducers  38  with different center frequencies such that the emitted ultrasonic signal beam includes signals with different frequencies. For example, the ultrasonic signal beam may include ultrasonic signal  32 - 1 , ultrasonic signal  32 - 2 , and ultrasonic signal  32 - 3 . Signals  32 - 1 ,  32 - 2 , and  32 - 3  may have different frequencies and/or may each include multiple frequencies (e.g., with different amplitudes). The ultrasonic signal beam may bounce off of one or more specular reflection points such as specular reflection points C1 (e.g., on the user&#39;s face  74 ). C2 (e.g., on cornea  30 ), and C3 (e.g., on sclera  28 ). Because transmitting array  24 T is located a few centimeters away from the reflection points, control circuitry  26  may treat signals  32 - 1 ,  32 - 2 , and  32 - 3  as originating from a point source (instead of originating from transducers at different locations), if desired. Control circuitry  26  may analyze signals  32 - 1 ,  32 - 2 , and  32 - 3  received by array  24 R to determine the location of reflection points C1, C2, and/or C3. 
       FIG.  15    is a top view of illustrative gaze tracking circuitry  20  showing how multiple receiving arrays may be used to detect a reflected ultrasonic signal emitted from a single transmitting array. In the example of  FIG.  15   , only three arrays  24  are shown, but there may be additional arrays  24  surrounding eye  16 , if desired. During operation, control circuitry  26  may configure array  24 T to be a transmitting array and arrays  24 R to be receiving arrays. Array  24 T may include transducers  38  with different center frequencies such that the emitted ultrasonic signal beam includes signals with different frequencies. For example, the ultrasonic signal beam may include ultrasonic signal  32 - 1  and ultrasonic signal  32 - 2 . Signals  32 - 1  and  32 - 2  may have different frequencies and/or may each include multiple frequencies (e.g., with different amplitudes). The ultrasonic signal beam may bounce off of one or more specular reflection points such as specular reflection points C1 (e.g., on cornea  30 ), and C2 (e.g., on sclera  28 ). Control circuitry  26  may analyze signals  32 - 1  and  32 - 2  received by arrays  24 R to determine the location of reflection points C1 and/or C2. 
     If desired, control circuitry  26  may tune the transmission properties (e.g., phases and/or amplitudes) of array  24 T to reduce the amplitude of signals directly transmitted from transmitting arrays  24 T to receiving arrays  24 R. In the event that direct transmission from transmitting arrays  24 T to receiving arrays  24 R remains too large, one or more additional transmitting arrays  24 T may be used to transmit a signal (e.g., steered away from the user&#39;s eye) that partially or completely nullifies the direct transmission from transmitting arrays  24 T to receiving arrays  24 R, if desired. 
     Cornea  30  and sclera  28  may be approximately spherical. If desired, control circuitry  26  may determine the locations of reflection points C1 and/or C2 as a function of the sphere center and/or sphere radii of cornea  30  and/or sclera  28 . For example, the location of reflection point C1 may be determined as a function of cornea center c s . 
       FIG.  16    is a top view of illustrative gaze tracking circuitry  20  showing how a single transmitting array and a single receiving array may be used to determine a location of the center of the cornea. In the example of  FIG.  16   , only two arrays  24  are shown, but there may be additional arrays  24  surrounding eye  16 , if desired. During operation, control circuitry  26  may configure array  24 T to be a transmitting array and array  24 R to be a receiving array. Array  24 T may include transducers  38  with different center frequencies such that the emitted ultrasonic signal beam includes signals with different frequencies. For example, the ultrasonic signal beam may include ultrasonic signal  32 - 1  and ultrasonic signal  32 - 2 . Signals  32 - 1  and  32 - 2  may have different frequencies and/or may each include multiple frequencies (e.g., with different amplitudes). The ultrasonic signal beam may bounce off of one or more specular reflection points such as specular reflection points C1 (e.g., on cornea  30 ) and C2 (e.g., on sclera  28 ). When approximating the cornea as a spherical shape, a bisecting line separating equal angles θ between the emitted signal path and the reflected signal path (reflected from point C1, for example) will pass through the cornea center location c s . If the radius r s  of cornea  30  is known, control circuitry  26  may analyze signals  32 - 1  and  32 - 2  received by array  24 R to determine the location of cornea center c s . Control circuitry  26  may use the cornea radius r s  and cornea center location c s  to solve for the gaze direction. 
     The examples of  FIGS.  14 ,  15 , and  16    are merely illustrative. If desired, control circuitry  26  may employ other techniques to gather information about the user&#39;s eye during operation of glasses  14 . For example, control circuitry  26  may combine path length information from several reflection paths off of the cornea and/or sclera to determine gaze angle. This technique may be advantageous in situations where path length can be measured with more precision than the incident angle of the reflected signal. 
     The foregoing is merely illustrative and various modifications can be made to the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20210419
Publication Date: 20240820
Grant Date: 20240820
Priority Date: 20200423
Inventors: ARBABI, Ehsan
GILL, Patrick R.
WANG, AVERY L.
Assignee: APPLE INC
CPC Classifications: [{"code": "G01S15/003", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S15/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S7/521", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S15/88", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/013", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01S15/88", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S15/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S7/521", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S15/003", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/013", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01S15/88", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S15/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S15/003", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S7/521", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/013", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 92305767