Apple desires to embed antennas in screens in addition to Contact ID

Future Apple devices may make more use of the screen to provide a larger Touch ID under the display, and improve WiFi and cellular reception by embedding a larger antenna.

This is the tradeoff Apple has made for years – how we can get better signal reception and secure user authentication while reducing frames and notches. Now Apple may have found ways to get edge-to-edge displays that include both Touch ID and an antenna.

With all that said, not much has been discussed about why moving the sensor under the display is so complex that Apple didn’t. A newly uncovered patent application describes the problems in detail and suggests solutions in which a display is built up from layers that allow more than just light to pass through.

In addition to allowing Touch ID under the display, a related patent application includes using these layers to incorporate an RF antenna into the screen. The signals required for Wi-Fi and cellular communications require exposed antennas. Hence, one that takes up the entire area of ​​an iPhone display should be better than a narrow band on the side of the device.

Touch ID under the display

“Improved recognition of fingerprints under the display using angle-focused filters with a narrow field of view,” was submitted by Apple in June 2019, but has only now been revealed.

“Fingerprint recognition and matching is often used as a reliable technique for personal identification or verification,” she begins. Without recognizing that Face ID even exists, the patent application then makes an argument for why Touch ID is still useful.

“An optical fingerprint sensor can be particularly advantageous for checking and / or authentication in an electronic device and in particular a portable device,” it says. “When an optical fingerprint sensor is built into an electronic device or host device … the authentication can be performed quickly, for example by a processor of the host device.”

The problem is that if you want to rely on Touch ID, Touch ID has to be reliable and fast. This is especially a problem when the Touch ID sensor is small, e.g. B. with the old home buttons.

“One of the challenges faced by the optical fingerprint sensor is the persistence of performance over time because the glass-air interfaces are not stable enough to accommodate small areas,” the patent continues. “On the other hand, the large area sensors that use complementary metal oxide semiconductors (CMOS) are not inexpensive.”

“”[Then] Separating different reflection rays at different angles is another challenge as many lighting patterns must be used to separate the reflection rays, resulting in a long (e.g. a few seconds) image acquisition time, “it says.

The solution seems to be to make the Touch ID sensor larger, but not so big that it is expensive to manufacture or take up too much space on the device. Hence, finding a way to place the sensor under the display could solve the problems.

Most of the patent application then focuses on the difficulty of emitting light so that the display can show an image but then reflect an optical scan of a fingerprint back into the device.

Detail from the patent showing layers of a display with a finger (labeled 110) touching them

Apple’s proposal provides a display that “comprises a light-emitting layer, an optical layer, a filter layer and a pixelated image sensor”.

“The light-emitting layer is covered by a transparent layer and can illuminate a surface that is in contact with the transparent layer and enables reflected light to be transmitted from the surface to the optical layer,” says the patent application. “At least one of the optical layers or the filter layer enables angle-focused FOV filtering of the reflected light.”

The field of view is a field of view and central to this patent application is the idea that the displayed image and optical scanning for fingerprints can be done from different angles.

In one example, Apple suggests that the user’s finger can be “lit from the right side” and “the light emitted at an angle (e.g. 42 degrees) can be reflected … [to] reach an imaging area. ”

Throughout this patent application, Apple has been looking at occlusion, the process of which light is blocked by an object. However, if fingerprint scanning is performed from more than one angle, the device can account for the different occlusion each angle creates.

“This is because the additional occlusion pattern (second occlusion pattern), although referring to the same area of ​​touch, is different from the first occlusion pattern,” says Apple. “In addition, the lighting in different directions can lead to more occlusion patterns, with which the occlusion effect of the OLEDs of the touch display layer can be averaged and reduced.”

Two of the three recognized inventors – Mohammad Yeke Yazdandoost and Giovanni Gozzini – are also listed in a corresponding patent application. “Sensor system for detecting the incidence of light in a light-emitting layer of an electronic device display.” Similarly, it’s about embedding sensors in a display instead of hiding them under frames.

Embed the RF antenna in a display

A second newly uncovered patent application for a similar idea is credited to an entirely different team of four inventors, suggesting Apple is determined to make greater use of its displays.

In this case, “Display Integratable Hybrid Transparent Antenna” deals with the embedding of a radio front end module (RFEM) in a screen.

“Today’s wireless systems (e.g. smartwatches or other devices with a predominant display function) strive for a borderless display with a smaller bezel or a bezel-less display solution,” says the patent application.

Detail from the patent showing how signals can be sent to and from an in-screen antenna

“Especially for wearable devices such as smartwatches, smart glasses or smart health-related monitoring devices, the display is small and the number of radio devices (e.g. Bluetooth, GPS, WiFi, 3G / 4G /. LTE, FM, etc.) is small need to be supported, and the associated antennas are increasing. ”

Having mentioned that “antenna solutions for such devices can be challenging”, the patent application uses 12,000 words in which the proposed solutions are described in detail. The detail covers the different needs of all antennas, from Bluetooth to WiFi, but the general principle is the same for all.

Apple’s proposal is for a device that includes “a multilayer display including a liquid crystal display (LCD) layer, a touch panel layer, and a cover glass layer.”

“The device also includes an antenna configured to transmit the RF signals,” she continues. “The antenna includes a primary coupling feed structure that is configured to receive the RF signals from the radio front-end module via a feed line. The antenna also includes a generating structure that is configured to radiate the RF signals.”

There are then problems with retrieving the signals from and to the antenna. The point, however, is that by embedding an antenna in the display, that larger area is created for reception without losing any showroom.

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