An optical scanning device (15) includes a reference light guide part (50); a sub-light guide part (40); a reference holding structure (53) which includes a reference reception part (55) configured so as to be in contact with the reference lens (52) deflected in a sub-scanning direction; a sub-holding structure (45) which includes a sub-reception part (45) configured so as to be in contact with the sub-lens (42) deflected in the sub-scanning direction, wherein a deflection direction of the reference lens (52) coincides with a deflection direction of the sub-lens (42), and when it is assumed that the reference lens (52) and the sub-lens (42) are not deflected, an absolute value of a smallest distance between the sub-reception part (45) and the sub-lens (42) is set to be equal to or larger than an absolute value of a smallest distance between the reference reception part (55) and the reference lens (52).

A housing includes a body having an opening. The body includes a peripheral portion that abuts on the opening. A cover covers at least a part of the opening. A seal is sandwiched between the cover and the peripheral portion of the body. At least one of the cover and the peripheral portion of the body includes a corner portion and a linear portion. The corner portion has a first shape that defines one of a gap between the cover and the peripheral portion of the body and a width of the seal. The linear portion abuts on the corner portion. The linear portion has a second shape that defines the one of the gap between the cover and the peripheral portion of the body and the width of the seal. The second shape is different from the first shape of the corner portion.

A housing includes a body having an opening. The body includes a peripheral portion that abuts on the opening. A cover covers at least a part of the opening. A seal is sandwiched between the cover and the peripheral portion of the body. At least one of the cover and the peripheral portion of the body includes a corner portion and a linear portion. The corner portion has a first shape that defines one of a gap between the cover and the peripheral portion of the body and a width of the seal. The linear portion abuts on the corner portion. The linear portion has a second shape that defines the one of the gap between the cover and the peripheral portion of the body and the width of the seal. The second shape is different from the first shape of the corner portion.

In an optical scanning device, an outer wall closest to a circumscribed circle of a rotating polygon mirror has a space in a position facing to a position of a reflection surface of the rotating polygon mirror in an axial direction of a rotating shaft. A part of a cover is provided in a position farther from the circumscribed circle than the outer wall so as to close the space, when the optical scanning device is viewed in a direction perpendicular to the axial direction of the rotating shaft.

In an optical scanning device, an outer wall closest to a circumscribed circle of a rotating polygon mirror has a space in a position facing to a position of a reflection surface of the rotating polygon mirror in an axial direction of a rotating shaft. A part of a cover is provided in a position farther from the circumscribed circle than the outer wall so as to close the space, when the optical scanning device is viewed in a direction perpendicular to the axial direction of the rotating shaft.

An optical writing device, and a method of controlling the optical writing device. The optical writing device and the method includes controlling speed of operation of a light deflector based on image magnifying-power information in a sub-scanning direction parallel to a direction in which a surface of a photoconductor moves, and controlling a prescribed write clock frequency such that a number of clock pulses of write light will become a target number of pulses over a period where the write light scans an area within a prescribed distance in a main scanning direction, the target number of pulses being maintained even when the speed of operation of the light deflector is changed in the controlling the speed of operation of the light deflector. The write clock frequency controller maintains the target number of pulses even when the speed of operation of the light deflector is changed by the light-deflector controller.

A housing includes a body having an opening. The body includes a peripheral portion that abuts on the opening. A cover covers at least a part of the opening. A seal is sandwiched between the cover and the peripheral portion of the body. At least one of the cover and the peripheral portion of the body includes a corner portion and a linear portion. The corner portion has a first shape that defines one of a gap between the cover and the peripheral portion of the body and a width of the seal. The linear portion abuts on the corner portion. The linear portion has a second shape that defines the one of the gap between the cover and the peripheral portion of the body and the width of the seal. The second shape is different from the first shape of the corner portion.

A housing includes a body having an opening. The body includes a peripheral portion that abuts on the opening. A cover covers at least a part of the opening. A seal is sandwiched between the cover and the peripheral portion of the body. At least one of the cover and the peripheral portion of the body includes a corner portion and a linear portion. The corner portion has a first shape that defines one of a gap between the cover and the peripheral portion of the body and a width of the seal. The linear portion abuts on the corner portion. The linear portion has a second shape that defines the one of the gap between the cover and the peripheral portion of the body and the width of the seal. The second shape is different from the first shape of the corner portion.

An image forming apparatus with accurate color shift correction with consideration of a change in a rotational speed of a driving portion of a laser scanning member includes a light source, the laser scanning member, a driving portion, a speed controlling portion, a light detecting portion, a light source controlling portion, a scanning lens, a housing, a temperature gradient detecting portion, a first temperature detecting portion, and a correction processing portion. The temperature gradient detecting portion detects a temperature gradient in the housing. The first temperature detecting portion detects a temperature of the scanning lens. The correction processing portion corrects an emission start timing at which light corresponding to a line of image data is emitted from the light source, based on the temperatures detected by the temperature gradient detecting portion and the first temperature detecting portion, the rotational speed of the driving portion, and a preset arithmetic expression.

A scale and scanner system includes a controller to control operation of the scale and scanner system. A scale calibration parameter memory for storing scale calibration parameters is coupleable to the controller. A scanning module and a scale module are coupleable to the controller. When the controller is not coupled to the scanning module or scale module, the scale calibration parameter memory remains in the system.