Scanning optical device and image forming apparatus

A scanning optical device for scanning a scanned member with a light beam depending on image information;

• the scanning optical device comprising:
• a first lens through which the light beam emitted from a light source is transmitted;
• a light deflector including a rotatable polygon mirror for deflecting and scanning the light beam transmitted from the first lens;
• a second lens through which the light beam deflected and scanned by the light deflector is transmitted;
• a mirror configured to reflect the light beam transmitted from the second lens and to guide to the scanned member;
• a casing configured to hold the first lens, the light deflector, the second lens and the mirror, the casing including an edge portion for forming an opening through which the first lens, the light deflector, the second lens and the mirror are mounted on the casing;
• a first spring configured to urge one end of the mirror to the casing with respect to a longitudinal direction of the mirror and a second spring configured to urge the other end of the mirror to the casing;
• a first lid configured to cover a part of the opening;
• and
• a second lid configured to cover the mirror, the first spring and the second spring,
• wherein a direction from a first seat surface, of the casing, which holds the light deflector and toward the light deflector and perpendicular to the first seat surface, and a direction from a second seat surface, of the casing, which holds the second lens and is parallel to the first seat surface toward the second lens held by the second seat surface and perpendicular to the second seat surface are the same direction,
• wherein as the scanning optical device is viewed in a rotational axis direction of the rotatable polygon mirror from a side of the first lid, the first lid does not cover the mirror and covers the first lens and the rotatable polygon mirror, and
• wherein in a state in which the part of the opening is covered by the first lid, the first lens and the rotatable polygon mirror are in a space formed and obstructed by the first lid, the casing and the second lens held by the second seat surface.

A scanning optical device for scanning a scanned member with a light beam depending on image information;

• the scanning optical device comprising:
• a first lens through which the light beam emitted from a light source is transmitted;
• a light deflector including a rotatable polygon mirror for deflecting and scanning the light beam transmitted from the first lens;
• a second lens through which the light beam deflected and scanned by the light deflector is transmitted;
• a mirror configured to reflect the light beam transmitted from the second lens and to guide to the scanned member;
• a casing configured to hold the first lens, the light deflector, the second lens and the mirror, the casing including an edge portion for forming an opening through which the first lens, the light deflector, the second lens and the mirror are mounted on the casing;
• a first spring configured to urge one end of the mirror to the casing with respect to a longitudinal direction of the mirror and a second spring configured to urge another end of the mirror to the casing;
• and
• a lid configured to cover a part of the opening,
• wherein a direction from a first seat surface, of the casing, which holds the light deflector and toward the light deflector and perpendicular to the first seat surface, and a direction from a second seat surface, of the casing, which holds the second lens and is parallel to the first seat surface toward the second lens held by the second seat surface and perpendicular to the second seat surface are the same direction,
• wherein the light beam reflected by the mirror is emitted from an emitting opening provided on the casing to an outside of the scanning optical device,
• wherein as the scanning optical device is viewed in a rotational axis direction of the rotatable polygon mirror from a side of the lid, the lid covers the first lens and the rotatable polygon mirror, and further covers at least the first spring and the second spring, of the mirror, the first spring and the second spring,
• wherein the lid is provided with an opening or a cutout portion through which an inside of the casing is exposed on a downstream side of the second lens in an optical axis direction of the light beam passing through the second lens and an advancing direction of the light beam passing through the second lens, and
• wherein in a state in which a part of the opening of the casing is covered by the lid, the first lens and the rotatable polygon mirror are in a space formed and obstructed by the lid, the casing and the second lens held by the second seat surface.