Rotatable mirror arrangement for generating a scanning beam which is displaced in steps parallel to itself

Claim 1

A rotary mirror assembly for dividing a generally continuous incident beam of light into a plurality of parallel spaced apart scanning beams; said assembly comprising: (a) a rotary body mounted for rotation about an axis of rotation; (b) a plurality of mirrors secured to said body and projecting radially therefrom with each of said mirrors presenting a mirror surface generally perpendicular to said axis of rotation; said mirrors arranged on said body with adjacent mirrors displaced axially and angularly; each of said mirrors being axially spaced from adjacent mirrors by the same predetermined axial spacing; each of said mirrors covering only an angular segment of a plane perpendicular to said axis with adjacent mirrors being angularly displaced for a light beam impinging a mirror to leave said mirror as said body rotates and impinge an adjacent mirror; (c) means for rotating rotating said body about said axis; (d) light beam generating means for projecting a generally continuous incident beam of light in a constant straight line with said beam reflecting off of each of said mirror surfaces as said body rotates with reflected light from each of said mirror surfaces comprising said plurality of parallel spaced-apart scanning beams; and (e) said light beam generating means disposed for said incident beam to project at an angle with said rotational axis and to impinge upon only one mirror of said plurality of mirrors at a time near a radially outer edge of said one mirror and with said incident beam and reflected scanning beams cooperating to define a scanning plane parallel to and spaced from said axis; and said incident beam intersecting a plane perpendicualr to said scanning plane at a point dividing in half a distance between farthest axially displaced mirrors of said assembly.