Mar 17, 2021 News
Apple hopes that iPhone and iPad screens can better recognize touches and gestures even in wet or humid environments. A newly obtained patent shows that Apple is studying how to compensate for wet fingertips and make the screen respond the way you want.
This Apple patent called 'Fingerprint Assist Force Estimation' focuses on using pressure to distinguish accidental touches and deliberate touches on a capacitive screen when wet. Apple said that under normal circumstances, capacitive sensing touch screens do not measure the force exerted on the screen or cover glass but instead measure the presence or absence of a touch and the touch's size. The touch force or the change in touch force can be interpreted as additional input besides simple touch, multi-touch, contact, and/or close-range input.
Generally, force is considered to be the amount of pressure exerted on the screen. The more energy transferred from the screen, the more contact, and therefore, the greater the force exerted. The connection between the fingerprint and the touch surface is used to determine the magnitude of the applied force; that is, the degree of wetting of the fingerprint's touch surface is interpreted as the magnitude of the applied force.
Therefore, if the screen can detect how wet a person's fingers are, it can recalibrate itself to determine better when the touch was deliberate or not. It may work on the principle that a wet finger presses on the screen slightly more than a dry finger spreads out. In wet conditions, the ridges and valleys of fingerprints may be more malleable and may provide better contact, while dry conditions may cause the opposite result.
The patent describes a calibration device designed to determine the current state of the user's fingerprint. The button or input can be configured with a mechanical actuator that is actuated at a known level of applied force; that is, the amount of touch sensed at the moment of actuation can have a known force be used for calibrating fingerprint assist force estimation.
The rest of the patent mainly studies the different equipment types that may be useful and the specific details of how the procedures will change by then. But in general, the goal is to figure out how wet the user's fingers are. Then, based on the humidity readings and the fingerprints' size on the device, it is inferred when to make a touch or tap response.