Switch assembly for an electronic system of a drug delivery device

A switch assembly for an electronic system of a drug delivery device, the switch assembly comprising:

• a chassis supporting a printed circuit board assembly (PCBA) comprising at least a first electrical contact, a second electrical contact, a third electrical contact and a fourth electrical contact;
• a ring having an annular ratchet profile;
• wherein the chassis moves axially relative to the ring from a first axial position to a second axial position during a first switch operation mode, and wherein the chassis and the ring are configured such that the ring rotates relative to the chassis during a second switch operation mode,
• wherein the first electrical contact and the second electrical contact are arranged such that upon axial movement of the chassis towards the ring during the first switch operation mode, an electrical connection between the first electrical contact and the second electrical contact is closed,
• and wherein an elastically deformable arm is radially interposed between the annular ratchet profile of the ring and the chassis, is axially and rotationally constrained to the chassis and is guided on the annular ratchet profile such that the arm at least during the second switch operation mode elastically deforms in a radial direction towards the chassis thereby alternately opening and closing an electrical connection between the third electrical contact and the fourth electrical contact via the arm.