As more and more PCs and phones now integrate fingerprint sensors or iris scanners, it seems that biometric authentication is well on the way to replace passwords. Microsoft did contribute to this paradigm shift over the past few years, integrating iris scanners in its latest Surface devices and Lumia phones, as well as fingerprint scanners in select Surface Type Covers or the freshly released Modern Keyboard.
As of today though, Microsoft has never directly integrated fingerprint scanners on its devices, unlike many of its OEM partners. It's possible that the company considers iris scanners more convenient, though users may disagree. But to be fair, fingerprint scanners have also been criticized, especially with manufacturers placing them on the back of mobile handsets to reduce screen bezels. According to the rumor mill, many companies including Apple are working hard to integrate fingerprint scanners directly into touch screen displays, and Microsoft apparently did not rest on its laurels either.
As spotted by Microsoft watcher WalkingCat, Microsoft has received a patent for an under-display fingerprint sensor, which was originally filed in July 2016.
The patent describes different implementations a fingerprint detection system using an image sensing display. The main idea is using a photoemitter and a photodetector under the display, in combination with a sensing trigger that would launch the imaging scan when a finger touches the display. In the description, Microsoft explains that many fingerprint detection systems currently in use have several limitations:
For example, bezel-less or very small bezel devices do not leave sufficient area for fingerprint detection components outside of the display area. Furthermore, capacitive sensing is very sensitive to the distance between the finger and the sensor, such that the cover glass of a display of a computing device may dramatically reduce the effectiveness of the capacitive sensing resolution if the capacitive sensing components are positioned beneath the display. Ultrasonic sensing is accompanied by noise issues and manufacturing issues (including detrimental mechanical impedance between the sensor and the display surface). Lensed digital cameras tend to be bulky and expensive. Many such solutions also tend to be difficult to scale in area across the area of the computing device front face or display.
It remains to be seen if this technology will ever be applied to an upcoming Microsoft product. For now, it seems that iris scanners are not always as reliable or fast as fingerprint scanners, but they're probably a more inclusive technology, just like the built-in eye tracking support in Windows 10. However, it's clear that fingerprint scanners sooner or later become integrated right into touch screen displays, but for now, Samsung and Apple are probably more interested in making it a reality for now.