To provide a shading correction signal generation device including a correction amount setting signal generator that generates a correction amount setting signal, a modulator that modulates the correction amount setting signal by a predetermined modulation scheme and outputs the modulation signal, and a filter circuit that filters the modulation signal to generate a shading correction signal. During a transition period, the correction amount setting signal generator generates the correction amount setting signal in which a difference between a level at an end of a predetermined period and an average level during the transition period is larger than a difference between the level at the end of the predetermined period and a level at a start of a shading correction period.

An optical scanning apparatus includes a first light source, a second light source, a first driving element, a second driving element, a rotatable polygonal mirror, a first scanning optical portion, a second scanning optical portion, a detecting element, and a circuit board. The first light source, the first driving element and the detecting element are arranged in a named order on the circuit board. The following relationship is satisfied: 1>2, where 1 is an angle formed by a direction of the first laser light and a first direction, and 2 is an angle formed by a direction of the second laser light and a second direction.

An image forming apparatus includes a laser scanner unit, an engine controller, and an image controller. The laser scanner unit includes a polygon mirror configured to reflect a laser beam to scan a photosensitive drum, and a BD sensor configured to detect the laser beam reflected by the polygon mirror to output a BD signal. The engine controller generates an image formation BD signal synchronized with the BD signal. The image controller identifies a reference reflection face based on the number of times of low levels of an image formation BD signal that has been sampled for a predetermined period from a falling edge of the image formation BD signal. The image controller corrects image data based on the identified reflection face to control image formation processing.

An image forming apparatus for forming an image in accordance with image information on a sheet includes a photosensitive member; a scanner unit for scanning the member with a laser beam in accordance with the information, the scanner unit including a source for emitting the beam, a deflector having a polygonal mirror for reflecting the beam to deflect it, and a sensor for receiving the beam deflected by the deflector; a controller for controlling scanning start timing of the beam in response to an output of the sensor. A reference position of scanning lines of the beam in a sub-scan direction and a center position of a receipt surface of the sensor in the direction are deviated from each other. For all scanning lines by reflecting surfaces of the rotatable polygonal mirror, only parts, in the direction, of the scanning lines pass the receipt surface of the sensor.

An image forming apparatus has a changing portion configured to change, based on a detection result of a temperature sensor, response sensitivity in starting of power supply by a determination portion based on a detection result of a human body detection sensor in a case where a human body approaches the human body detection sensor. The changing portion increases the sensitivity in a case where a temperature detected by the temperature sensor is a second temperature lower than a first temperature than in a case where the temperature detected by the temperature sensor is the first temperature.

An image forming apparatus includes a plurality of photosensitive members; a scanner unit including light sources, a rotatable polygonal mirror, and reflecting members; and a fixing portion. Parts of the laser beams emitted from the light sources are reflected by the rotatable polygonal mirror toward the fixing device side, and rest parts of the laser beams are reflected by the rotatable polygonal mirror toward a side opposite from the fixing device side. Of the parts of the laser beams reflected by the rotatable polygonal mirror toward the fixing device side, the laser beam reflected toward the reflecting member provided at a position remotest from the rotatable polygonal mirror travels downward relative to a horizontal direction. A rotational axis of the rotatable polygonal mirror is inclined relative to a vertical direction.

An image forming apparatus includes first and second photoconductive drums, and a laser scanning unit including a plurality of optical elements configured to direct a first scanning beam to the first photoconductive drum from a first side of, and at a first incidence angle with respect to, a first line passing through a center of the first photoconductive drum and a second scanning beam to the second photoconductive drum from a second side of, and at a second incidence angle with respect to, a second line passing through a center of the second photoconductive drum. Magnitudes of the first and second incidence angles are substantially the same, and a second side of the first line and a first side of the second line are each between the first side of the first line and the second side of the second line.

An optical sensor includes a first LED, a second LED, a first PD, and a second PD. The first LED and the second LED are configured to irradiate an optical-axis center point of an intermediate transfer belt. The first PD is arranged at a position at which specularly reflected light of light emitted from the first LED and diffused reflected light of light emitted from the second LED are received. The second PD is arranged at a position at which diffused reflected light of the light emitted from the first LED is received.

A leaf spring configured to mount an optical element to a housing, the housing containing: a rotary polygon mirror configured to deflect a laser beam emitted from a light source; and the optical element configured to guide the laser beam deflected by the rotary polygon mirror to a member to be scanned, wherein an adhesive is applied to the leaf spring, the adhesive being configured to adhere separated material scraped from the housing, the separated material being scraped from the housing by rubbing between the leaf spring and the housing at a time of mounting the optical element to the housing.

An image forming apparatus includes a plurality of photosensitive members; a scanner unit including light sources, a rotatable polygonal mirror, and reflecting members; and a fixing portion. Parts of the laser beams emitted from the light sources are reflected by the rotatable polygonal mirror toward the fixing device side, and rest parts of the laser beams are reflected by the rotatable polygonal mirror toward a side opposite from the fixing device side. Of the parts of the laser beams reflected by the rotatable polygonal mirror toward the fixing device side, the laser beam reflected toward the reflecting member provided at a position remotest from the rotatable polygonal mirror travels downward relative to a horizontal direction. A rotational axis of the rotatable polygonal mirror is inclined relative to a vertical direction.