Patent ID: 7057781
Filing Date: 2006-06-06
Classification: B41J,G02B

Abstract:
1. An optical scanning apparatus comprising: incidence optical means for causing a beam emitted from light source means to be incident on deflecting means; and scanning optical means for causing the beam reflected and deflected by the deflecting means to be imaged on a surface to be scanned, wherein said scanning optical means has a first lens on the deflecting means side, and has a second lens on the surface to be scanned side, wherein each of the first and second lenses comprises a toric lens of which both surfaces have toric surfaces, wherein the first lens has negative power in the sub-scanning direction, and the second lens has positive power in the sub-scanning direction, and wherein when the radius of curvature of the surface of the first lens which faces the deflecting means in the main scanning direction and the radius of curvature thereof in the sub-scanning direction are defined as R1m and R1s, respectively, the radius of curvature of the surface of the first lens which faces the surface to be scanned in the main scanning direction and the radius of curvature thereof in the sub-scanning direction are defined as R2m and R2s, respectively, the radius of curvature of the surface of the second lens which faces the deflecting means in the main scanning direction and the radius of curvature thereof in the sub-scanning direction are defined as R3m and R3s, respectively, and the radius of curvature of the surface of the second lens which faces the surface to be scanned in the main scanning direction and the radius of curvature thereof in the sub-scanning direction are defined as R4m and R4s, respectively,