Means to Integrate a Touch ID Sensor into a Touchscreen Display

The subject of this Display Daily article is a technology under development at Apple and in the news during the past few days. To put this development interest into context, recall that the iPhone has a fairly large bezel located below the display that is occupied by a circular home button/touch ID fingerprint sensor.

If Apple wanted to minimize bezel areas, as is generally considered desirable in smartphones, the company needs to address the issue of where and how to relocate the touch ID fingerprint sensor. A just published Apple patent application addresses this issue by disclosing means to integrate the touch ID fingerprint sensor into the display touchscreen.

Apple’s US patent application is entitled “Fingerprint Sensor in an Electronic Device” and has been assigned number 2015/0036065. It was published on February 5 and can be found online here.

The application discloses several embodiments of the invention including means to:

  • Scan a single fingerprint at a predefined, single location on the display.
  • Scan a single fingerprint at any location on the display.
  • Scan multiple fingerprints either sequentially or all at once.
  • Scan a full palm print.

The idea of embedding a fingerprint sensor into a touchscreen is not new. Other companies have been developing approaches based on various optical and electrical effects. These approaches typically call for adding additional layers to the display stack. Concerns exist, however, with such approaches. These relate to their potential for reducing image quality and/or the sensitivity to detect conventional touch inputs.

In its latest application, Apple addresses these concerns by disclosing means in which a fingerprint sensor is implemented as an integrated circuit connected to the bottom surface of a cover sheet, near the bottom surface, or connected to a top surface of the display. It is stated that it’s possible to implement multiple sensors. Other disclosed details include the use of so-called “blind vias” formed in the cover sheets, the inclusion of optional conductive sheets in the display stack and means of connecting the sensor to electronics located near the display.

Another means of detection disclosed in the application is based on the use of in-cell, ultrasonic piezoelectric sensors.

The application goes on to discuss the means to implement a full-panel combined touch and fingerprint sensor. In this case, proposed approaches include both capacitive- and ultrasonic-based means.

If the patent were to issue with the claims as they appear in the application, then the patent coverage would appear to be quite broad. -Arthur Berman