Sensor assembly, furniture and method for detecting activity of a user of a furniture

A method for detecting an activity of a user of a furniture with at least one sensor assembly, the at least one sensor assembly comprising a light transmitter and a light receiver, which form beginning and end of an optical light path, which connects the light transmitter and the light receiver to one another, and an oscillating body, which is arranged movably in such a way that a movement of the oscillating body results in a change in a property of the light path, the method comprising:

• transmitting a first amount of light from the light transmitter via the light path to the light receiver;
• generating, with the light receiver, a reception signal based on a second amount of light received via the light path;
• converting the activity of the user into a change in the movement of the oscillating body relative to the light path;
• generating a motion signal based on at least the second amount of light or on a signal derived from the second amount of light;
• and
• recognizing, based on the motion signal, in particular based on a change in the motion signal, the activity of the user,
• wherein the oscillating body has a resonant frequency of less than 20 Hz.