Apple Inc.
Systems and methods for determining physiological signals using ambient light

Abstract:

This relates to systems and methods for determining one or more physiological signals of a user using ambient light. The systems and methods can include one or more light sensors configured to measure light that has interacted with a user and one or more light sensors configured to measure ambient light. The gain of the one or more light sensors can be adjusted based on the levels of measured ambient light. For example, the gain of the one or more light sensors can be increased when ambient light levels are low (e.g., a low light environment), or the gain of the one or more light sensors can be decreased when ambient light levels are high (e.g., a bright light environment). In some examples, the systems can include a variable opacity element whose transmission properties (e.g., opacity and/or selected one or more wavelengths to pass through) can be varied.