Previous 'button type' modules required you to press a finger on a raised square or circular button for your fingerprint to be read exactly, so the sensor was usually mounted on the front, rear or side buttons of a smartphone. For example, Apple uses its round home button as the fingerprint sensor.
LG cut a shallow furrow of 0.01inches (0.3mm) thick on the lower backside of the cover glass and installed the fingerprint sensor inside of it. With this design, the sensor is not exposed to the outside of the device. High-strength cover glass protects the sensor and prevents it from coming in direct contact with water or damage from scratches.
The new module has a false acceptance rate (FAR) of 0.002%. The FAR is the probability that the system falsely recognizes someone else's biometric information as that of the user.
To adhere the sensor to the inside of the glass, LG developed a proprietary adhesive. The adhered side of the sensor and glass is just 0.0098inches (0.25mm) thick, but it can endure an impact of a 4.6 oz (130grams) steel ball dropped from 7.9-inches (20cm).
Apple has long been rumored to be working on an iPhone with no button and an ultra-thin display that integrate fingerprint sensors; however, we've yet to see any hardware leaks confirming those reports.
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