Optical: systems and elements – Deflection using a moving element
Reexamination Certificate
1999-06-24
2001-08-14
Schuberg, Darren (Department: 2872)
Optical: systems and elements
Deflection using a moving element
C359S711000
Reexamination Certificate
active
06275318
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a linear imaging optical system in which light flux from a light source is formed as a linear image, and the light flux in the form of the liner image is made incident on a reflection surface of a light deflector in the optical scanning system.
2. Description of the Related Art
In a laser printer or other such scanning optical systems, in order to correct facet-error of a reflection surface of a polygon mirror (a light deflector), light flux from a light source is formed as a linear image, and the light flux in the form of the linear image is made incident on the light deflector for scanning. In such a scanning optical system, a linear image forming single lens element has been known. More concretely, a linear image forming single lens element is a single lens element having the collimating function for making diverging light flux from a light source parallel, and the function of a cylindrical lens element for forming a linear image. However, in a linear image forming single lens element of the prior art, the correcting of aberrations has disadvantageously been insufficient on cross-sections which are inclined with respect to the direction of the linear image and the direction perpendicular to the linear-image. It has also been known that a linear image forming single lens element of this type has conventionally employed an aspherical surface for the purpose of correcting various aberrations. A complex configuration of an aspherical surface could be designed to have sufficient optical performance; however, actual optical performance of the lens element is not always satisfactory due to production error, because such an aspherical surface has high decentering sensitivity.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a linear imaging lens element for a scanning optical system in which light flux from a light source is formed, in the vicinity of a reflection surface of a light deflector, as a linear image through which the correcting of aberrations on cross-sections, which are inclined with respect to the direction of the linear image and the direction perpendicular to the linear-image, can satisfactorily be made. Furthermore, yet another object of the present invention is to provide a linear imaging lens element which has low decentering sensitivity, so that even if production error exists, there is little deterioration in the optical performance thereof.
In order to attain the above-mentioned objects, there is provided a linear imaging lens element for a scanning optical system in which light flux from a light source is formed, in the vicinity of a reflection surface of a light deflector, as a linear image having (A) a progressive power toric-aspherical surface, provided on either a surface facing the light source or on a surface facing the deflector; wherein cross-sectional configurations, being parallel with the plane including the optical axis and being perpendicular to the linear image, are made to be a circular arc, and the radius of curvature of each circular arc cross-sectional configuration is independently determined from the cross-sectional configuration lain on the plane which includes the optical axis and is parallel with the linear image; and having (B), on the opposite surface of the progressive power toric-aspherical surface, at least one of,
(b1) a spherical surface,
(b2) a toric surface having an axis of rotation on the plane including the optical axis and being parallel with the linear image,
(b3) a toric-aspherical surface having an axis of rotation on the plane including the optical axis and being parallel with the linear image, and the non-circular arc cross-sectional configuration on the defined plane, and
(b4) a progressive power toric-aspherical surface which is the same as that of item (A).
An laser diode, which is generally used as a light source, has different beam divergence with respect to the directions perpendicular to each other. The direction of the linear image preferably coincides with the direction of the larger beam divergence.
A linear imaging lens element according to the present invention preferably satisfies the following condition when one surface thereof is a spherical surface:
−0.8<ry
1
/ry
2
<0.3 (1)
wherein:
ry
1
designates the radius of curvature of the surface, facing the deflector, on the plane including the optical axis and being parallel with the linear image; and
ry
2
designates the radius of curvature of the surface, facing the light source, on the plane including the optical axis and being parallel with the linear image.
The present disclosure relates to subject matter contained in Japanese Patent Application No. 10-179910 (filed on Jun. 26, 1998) which is expressly incorporated herein by reference in its entirety.
REFERENCES:
patent: 5255113 (1993-10-01), Yoshikawa et al.
patent: 5453870 (1995-09-01), Iima
patent: 5541760 (1996-07-01), Iizuka
patent: 5648865 (1997-07-01), Iizuka
patent: 6052236 (2000-04-01), Nakasuji et al.
patent: 9258099 (1997-10-01), None
Kamikubo Junji
Koreeda Daisuke
Asahi Kogaku Kogyo Kabushiki Kaisha
Greenblum & Bernstein P.L.C.
Schuberg Darren
LandOfFree
Linear imaging lens element for a scanning optical system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Linear imaging lens element for a scanning optical system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Linear imaging lens element for a scanning optical system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2510947