Optical scanning device and image forming apparatus

An optical scanning device, comprising:

• an optical housing;
• an elongated optical element arranged in the optical housing, the elongated optical element having a first surface and a second surface extending in a main-scanning direction;
• a retaining member provided at a side opposite to a surface of the optical housing on which the elongated optical element is arranged, the retaining member being configured to maintain an attachment attitude of the elongated optical element in the optical housing;
• a scanning line curvature adjusting unit configured to adjust a curvature of the elongated optical element in a scanning line via the retaining member;
• a scanning line tilt adjusting unit configured to adjust a tilt of the elongated optical element in the scanning line by making the elongated optical element rotate on an axis of an optical axis direction via the retaining member;
• and
• an optical axis direction positioning unit configured to position the elongated optical element in the optical axis direction such that, when the elongated optical element is installed in the optical axis direction positioning unit, the optical axis direction positioning unit regulates the elongated optical element by applying pressure to end parts of the first surface such that pressure is not applied to the end parts the second surface of the elongated optical element, the optical axis direction positioning unit including,
• first receiving parts configured to regulate the end parts of the first surface of the elongated optical element in the main-scanning direction,
• a second receiving part configured to regulate a center part of the second surface of the elongated optical element in the main-scanning direction, and
• third receiving parts provided as auxiliary receiving parts in the optical housing, the third receiving parts configured to regulate parts of the elongated optical element at the second surface between the center part of the elongated optical element and the respective end parts of the elongated optical element in the main-scanning direction, wherein
• t+x<Y<t+2x·l/L is satisfied, where
• Y represents a distance in the optical axis direction between a receiving surface of the first receiving parts and a receiving surface of the third receiving parts, t represents a thickness in the optical axis direction of the elongated optical element, x represents a clearance between the optical axis direction positioning unit and the elongated optical element to enable the elongated optical element to be fitted, l represents a distance from the center of the elongated optical element in the main-scanning direction to the third receiving parts, and L represents a distance from the center of the elongated optical element in the main-scanning direction to the first receiving parts.