| 摘要 |
A socket (53) includes a socket body (64) provided with a socket surface (69) to which lamp device is attached. A cylindrical insertion port (68) through which a cap protrusion (36) of the lamp device is inserted is opened in the socket surface (69). A plurality of erroneous mounting preventing keys (71) protruded from positions separated from the socket surface (69) at specified positions of an inner circumferential surface of the insertion port (68). A distance (L2) from the socket surface (69) to the separated position of the erroneous mounting preventing key (71) is smaller than a distance (L1) from a front end surface (38) of the cap protrusion (36) to an attachment key (41). In a state where the front end surface (38) of the cap protrusion (36) contacts the plurality of erroneous mounting preventing keys (71), insertion of the cap protrusion (36) into the insertion port (68) is regulated, and rotation of the cap protrusion (36) in the insertion port (68) in the regulated state is possible. When the cap protrusion (36) rotates to a specified mount position with respect to the socket body (64), an erroneous mounting preventing groove of the cap protrusion (36) is inserted through the erroneous mounting preventing key (71), and the cap protrusion (36) can be inserted to a specified insertion position in the insertion port (68). |
