Light beam scanning optical system

A light beam scanning optical system, comprising:

• a light source;
• a luminous flux converging means for converging luminous flux emitted from the light source in straight line in the direction parallel to beam scanning plane;
• a deflection device disposed in the vicinity where luminous flux is converged into a straight line for deflecting the converged luminous flux at an equiangular velocity;
• a cylindrical mirror for turning and collecting luminous flux deflected by the deflection device onto the surface of photoconductor;
• and
• a cylindrical lens disposed between the cylindrical mirror and a light collecting point, wherein the relationship among the deflection device, cylindrical mirror and cylindrical lens fulfills the following three equations.
• .vertline.s/R.sub.M a.vertline.>0.5
• 0. 15<d/.vertline.R.sub.M a.vertline.<0.45
• (.vertline.d.sub.2 .vertline.+.vertline.d.sub.3 .vertline.)/.vertline.R.sub.M a.vertline.<0.45,
• wherein R.sub.M a is a radius of curvature of the cylindrical mirror, s is a distance from a point of reflection of luminous flux directed toward the center of scanning area by the deflection device to a light collecting point after reflection of deflection device, d is a distance from a point of reflection of luminous flux directed toward the center of scanning area by a deflection device to the cylindrical mirror, d.sub.2 is the thickness of cylindrical lens and d.sub.3 is a distance from plane of projection of the cylindrical lens to the light collecting surface.

A light bean scanning optical system, comprising:

• a light source;
• a luminous flux converging means for converging luminous flux emitted from the light source into a straight line in the direction parallel to the beam scanning plane;
• a deflection device disposed in the vicinity where luminous flux is converged into a straight line for deflecting the converged luminous flux at an equiangular velocity;
• a spherical mirror for turning and collecting luminous flux deflected by the deflection device into the surface of the photoconductor;
• and
• a cylindrical lens disposed between the spherical mirror and a light collecting point, wherein the relationship among the deflection device, the spherical mirror and the cylindrical lens fulfills the following three equations.
• .vertline.s/R.sub.M .vertline..gtoreq.0.5
• 0. 15.ltoreq.d/.vertline.R.sub.M .vertline..ltoreq.0.45
• (.vertline.d.sub.2 .vertline.+.vertline.d.sub.3 .vertline.)/.vertline.R.sub.M .vertline..ltoreq.0.45,
• wherein R.sub.M is a radius of curvature of the spherical mirror, s is a distance from a point of reflection of luminous flux directed toward the center of the scanning area by the deflection device to a light collecting point after reflection of the deflection device, d is a distance from a point of reflection of luminous flux directed toward the center of the scanning area by the deflection device to the spherical mirror, d.sub.2 is the thickness of the cylindrical lens, and d.sub.3 is a distance from the plane of projection of the cylindrical lens to the light collecting surface.