Using a structural internal element as a capacitive element to sense proximity

An electronic device, comprising:

• a housing at least partially defining an internal volume, the housing having a top portion, a bottom portion, and two side portions;
• a crown disposed on one of the side portions;
• a back cover connected to the bottom portion of the housing opposite the top portion;
• a securement feature configured to hold the back cover in contact with a user;
• and
• a capacitive proximity sensor disposed at least partially within the internal volume and in contact with an interior surface of the back cover, a portion of the capacitive proximity sensor including a cross-section spanning the interior surface of the back cover from an edge region below the crown toward a center region of the back cover.

An electronic device, comprising:

• a back cover defining:
• a top surface defining an interior surface;
• a bottom surface defining an exterior contact surface of the electronic device;
• an internal volume of the electronic device;
• and
• a central aperture formed in the back cover, the central aperture defined by the interior surface and the exterior contact surface;
• an electronic component disposed within the internal volume, the electronic component including a lower surface contacting the top surface of the back cover and contoured to mate with the top surface, and the electronic component being positioned around the central aperture;
• a sensing circuit disposed within the internal volume, the sensing circuit coupled to the electronic component;
• and
• a processor disposed in the internal volume, the processor configured to selectively operate:
• a first sensor comprising a capacitive proximity sensor including the electronic component and the sensing circuit;
• or
• a second sensor comprising the electronic component and the sensing circuit.