Apple is continuing to develop optical sub-display fingerprint technology, possibly for a future iPhone.
Although Apple’s iPhones have not had Touch IDs for several generations, there are rumors that the company is considering bringing the technology back. Past patent applications have also suggested this.
One Wednesday, the United States Patent and Trademark Office released two technology-related Apple patent applications.
The first, entitled “Optical transmission, reception or optical detection through the screen”, details the optical sensors which are integrated under the screen of a device. It opens to a background indicating that it may “be desirable to capture a two-dimensional (2D) or three-dimensional (3D) image of an object or user near a device”, such as an imprint digital.
With an optical sensor, receiver or transmitter positioned behind a screen, the patent says that “light can be transmitted or received through translucent openings extending from a front surface to a rear surface of a stack of device display. ”
“In this way, a transmitter, a receiver or an optical sensor can transmit or receive” by “a display”, the patent s.
Display stacks aren’t always 100% translucent, and Apple notes a method for handling opaque components. More precisely, certain opaque elements could be opaque at “certain wavelengths of light … but translucent at other wavelengths”. To bypass these opaque elements, it may be necessary to place translucent openings on a screen that extend beyond the opaque elements. From there, light can be collimated and directed through the apertures and to an optical receiver or an array of microlenses.
“For example, in some cases, an array of microlenses can be formed on the rear surface of the display stack”, according to the patent s. “Each microlens in the array can have a focal point located with, aligned with or near one of the translucent apertures.”
Combined with a similar optical transmitter, the technology could allow fingerprinting across a display surface (and despite non-transparent display components).
An illustration of the micro-lens array and the configuration of the transparent aperture. Credit: USPTO
Its inventors are Tong Chen, Mark T. Winkler, Meng-Huan Ho, Rui Liu, Xiao Xiang and Wenrui Cai. Among them, Chen has already worked on patents related to laser powered AirDrop.
In an apparent effort to combat the effects of temperature on OLED screens, this patent describes a method for compensating for temperature differences between signals.
“A temperature compensated signal can be produced by subtracting the first ing from the second ing”, the patent s.
Other parts of the patent describe various implementations, voltage specifications and component structures for an optical fingerprint sensor integrated into a screen.
As previously mentioned, Apple has continued to work on the potential technology for detecting fingerprints under the screen since the abandonment of Touch ID on the iPhone X in 2017.
However, patent applications are poor indicators of Apple’s future product plans. They also do not give a timetable as to when these devices could arrive on the market.