Patent ID: 7791983

Claim:
A timepiece movement, comprising: (1) a bottom plate, and (2) a display module including (a) a central bridge secured on the bottom plate, and having at least one positioning surface, and (b) an annular display member, with a rotational axis AA, having a contact surface; wherein the rotational axis AA passes through the central bridge, wherein the annular display member is mounted (i) to rotate freely substantially about the bridge, and (ii) to abut the bottom plate, wherein the bridge includes at least one positioning surface positioned to cooperate with the contact surface so as to position and maintain the display member, without the help of a separate holding plate, both (i) axially, in a direction opposite to that of the bottom plate, and (ii) radially, on the bottom plate about the axis AA, wherein the bridge includes three positioning surfaces formed by three protruding portions, and wherein the bridge further includes three assembly surfaces that are axially and angularly shifted relative to the positioning surfaces, and wherein the display member includes three lugs, the contact surface, the positioning and assembly surfaces and the lugs being arranged so as to form together a bayonet assembly system for mounting the display member on the bridge.