Today the U.S. Patent and Trademark Office officially granted Apple a patent that relates to various methods of implementing Touch ID on both future iPhones and Apple Watch. Technically, the patent covers digital acoustic imaging systems configured for use through an exterior surface having an arbitrary profile (e.g., curved, planar, and so on) of a portable electronic device.

Beamforming Optimization For Segmented Thin-film Acoustic Imaging Systems Incorporated In Personal Portable Electronic Devices

Apple's granted patent, which was never published as a patent application (under Apple) relates to acoustic imaging systems and, in particular, to acoustic imaging systems incorporated into electronic devices leveraged to capture images of fingerprints of users of those electronic devices. 

The surface may be a flat/planar surface, such as a display surface, or may be a curved surface such as a sidewall surface. In many examples, embodiments are configured to leverage adaptive beamforming techniques to (1) improve contrast uniformity across an imaging surface and (2) to improve overall signal to noise ratios by automatically reducing carrier noise via destructive interference.

For certain embodiments, a thin-film acoustic imaging system can include an array of imaging tiles, each tile including an array of independently-addressable thin-film acoustic transducers. In some examples, although not required, each transducer or at least one of the transducers is formed from polyvinylidene fluoride (PVDF) disposed over a semiconductor circuit (e.g., in a spin coating operation). 

Further, beamforming may be leveraged to improve image contrast and/or increase signal to noise ratio(s). In such examples, selected drive-mode transducers can be operated according to implementation-specific delays/phases in order to effect a particular increase or decrease of acoustic energy at a particular location, which may be at an imaging surface or, in other cases, at one or more selected sense-mode transducers.

In many implementations, an acoustic imaging system is positioned behind a display of an electronic device to facilitate through-display imaging of a user's fingerprint when that user touches the display.

In other implementations, an acoustic imaging system can be positioned relative to a housing of a hand-held electronic device to facilitate through-housing imaging of a user's fingerprint when that user handles the hand-held electronic device, such as by grasping a sidewall surface of the housing.

In yet other implementations, an acoustic imaging system can be positioned relative to a physical input device, such as a button (e.g., a power button) or crown, or key (e.g., of a keyboard), to facilitate imaging of a user's fingerprint when that user interacts with the physical input device.

Apple's patent FIG. 1A below depicts an example electronic device incorporating a thin-film acoustic imaging system defining an imaging surface above an active display area of the electronic device; FIG. 1B depicts an example electronic device incorporating a thin-film acoustic imaging system defining an imaging surface along a narrow segment of a housing sidewall of the electronic device; and FIG. 1C depicts an example electronic device incorporating a thin-film acoustic imaging system defining an imaging surface along another housing sidewall of the electronic device which has a larger scanning area.

Apple's patent FIGS. 1D-1i below depict examples of Touch ID for Apple Watch in various positions.

Apple's patent FIG. 6A above depicts a system diagram of a segmented acoustic imaging system. FIG. 6A illustrates single signal lines, whereas in many embodiments, multiple lines may be leveraged to convey differential signals; FIG. 7 depicts a different view of a system diagram of a segmented acoustic imaging system.

For more details, review Apple's granted patent US 11573665 B2.

Apple Inventors

• Marcus Yip: Sensing Hardware Electrical Engineer
• Brian King: Senior Technologist
• Jason Griesbach: Sr. Hardware Engineer
• Ehsan Khajeh: Sensor & Hardware Lead
• Aaron S. Tucker.: Hardware, Software, Firmware Prototyping Engineer
• Andrew Joyce: Hardware Engineer
• Giovanni Gozzini: Director of Engineering
• Moe (Mohammad) Yeke Yazdandoost: Tech Lead