Brother Kogyo Kabushiki-kaisha

Hiroki Yukawa

Hitoshi Fujino

Hiroyuki Ominato

Yoshifumi Nakamura

In a scanning optical apparatus, a third optical element is configured such that a first optical axis defined as an optical axis of an incident-side lens surface of the third optical element is inclined in a main scanning plane with respect to a normal line extending from a scanning center on a target surface to be scanned and an intersection point between the first optical axis and the incident-side lens surface is shifted with respect to the normal line, and that a second optical axis defined as an optical axis of an emission-side lens surface is inclined in the main scanning plane with respect to the first optical axis and an intersection point between the second optical axis and the emission-side lens surface is shifted with respect to the first optical axis.

Scanning optical apparatus

A scanning optical apparatus includes: a light source; a first optical element configured to convert light emitted from the light source into a beam of light; a second optical element configured to convert the beam of light having passed through the first optical element into a linear image extending in a main scanning direction; a deflecting mirror configured to deflect the beam of light having passed through the second optical element in the main scanning direction; and a third optical element configured to convert the beam of light having been deflected by the deflecting mirror into a spot-like image and focus it on a target surface to be scanned. The third optical element is a single lens having a pair of opposite lens surfaces, and each of the pair of lens surfaces is aspheric in a main scanning plane to satisfy the formula: 

In a scanning optical apparatus, light emitted from each of a plurality of light sources is converted by a first optical element into a beam of light, which in turn is converted by a second optical element into a linear image extending in a main scanning direction incident on a deflecting mirror at which the beams of light are deflected in the main scanning direction. A third optical element configured to convert the beams from the deflecting mirror into spot-like images is a single lens, and each of opposite lens surfaces thereof has a curvature in a sub-scanning direction varying continuously from a position corresponding to an optical axis thereof outward in the main scanning direction in such a manner that MTF values in a sub-scanning direction of an image formed on the scanned surface vary less with image height.

In a scanning optical apparatus including a single lens configured to convert a beam deflected by a polygon mirror into a spot-like image on a scanned surface, an angle &#x3b2;[deg] formed in a main scanning plane between the first optical axis and the second optical axis of the opposite lens surfaces of the lens satisfies the condition of &#x2212;0.6&#x3c;&#x3b2;&#x2266;&#x2212;0.1, and at least one of the conditions &#x2212;0.5&#x3c;&#x3b2;&#x3c;0 and &#x2212;0.1&#x3c;D&#x3c;0.2 are satisfied where &#x3b2;indicates an angle [deg] formed in the main scanning plane between the first optical axis and a reference line perpendicular to the scanned surface, and Dindicates an amount of shift [mm] in the main scanning plane, of a point of intersection between the second optical axis and the exit-side lens surface, from the first optical axis.

Growing community of inventors

Nagoya, Japan

Hiroki Yukawa