Patent attributes
A polygon mirror includes a reflective surface group having n number of reflective surfaces (M(1), . . . , M(n)) formed individually as outer peripheral side faces, a flat portion 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).
