摘要:
A polygon mirror (10) includes a mounting portion (12) and a plurality of reflective surfaces (14). The mounting portion (12) is mounted on a rotating body (30) having a support surface (32b). The mounting portion (12) has the shape of a polygonal plate. The plurality of reflective surfaces (14) are arranged around the rotating body (30) so as to surround the rotating body (30). A plurality of protrusions (18) configured to abut against the support surface (32b) of the rotating body (30) are arranged on one side of the mounting portion (12).
摘要:
A polygon mirror (10) includes a reflective surface group (14) having n number of reflective surfaces (M(1), ..., M(n)) formed individually as outer peripheral side faces, a flat portion (12) which shuts one end portion of the reflective surface group, and n number of pin gate traces (L(1), ..., L(n)) which are provided on the flat portion, correspond to the n number of reflective surfaces, individually, and are kept individually at distances from edge portions at which the reflective surfaces cross the flat portion. There are conditions DM(1) > DL(1)/2, ..., DM(n) > DL(n)/2 and DM(1) > DL(n)/2, ..., DM(n) > DL(n-1)/2, where DM(n) is a shortest distance from an edge portion at which the reflective surface M(n) and the flat portion cross each other to the pin gate trace L(n) and DL(n) is a shortest distance between the pin gate trace L(n) and the pin gate trace L(1).