A first mirror and a second mirror are disposed on a mounting surface of a housing in an exposure device of an image forming apparatus. A back surface of the first mirror is supported by ribs and the first mirror is pressed against the ribs by elastically pressing a reflecting surface thereof by a spring member. A reflecting surface of the second mirror is supported by ribs and the second mirror is pressed against the ribs by elastically pressing a back surface thereof by a spring member.

An example shutter unit includes a motor including a driving shaft to rotate in a first rotation direction and to rotate in a second rotation direction opposed to the first rotation direction, a first shutter part to selectively expose a light window by receiving a driving force transferred from the driving shaft when the driving shaft rotates in the first rotation direction or the second rotation direction, and a second shutter part to selectively expose a sensor by receiving the driving force transferred from the driving shaft when the driving shaft rotates in the second rotation direction.

Provided are a first seating face and a second seating face, to which a lower side of a holding member of an optical print head being moved from an exposure position toward a retracted position by a movement mechanism strikes in the direction of movement thereof. A light emission face of a lens array of the holding member that has abutted the first seating face and second seating face is thereby positioned on a movement path of a rubbing portion provided on a cleaning member that is inserted from an opening.

An information processing apparatus is configured to correctly detect a polygon face of a mirror being scanned even when noise occurs in a synchronization signal. The information processing apparatus is connected to an image forming apparatus including a laser light source configured to receive image data and output light; a photosensitive member; a polygon mirror, which has a plurality of reflection faces, and is configured to rotate to deflect a laser beam through use of the plurality of reflection faces, to thereby scan the photosensitive member; and a generator configured to generate a marking BD (beam detection) signal based on the deflected laser beam. The information processing apparatus receives a marking signal and determines whether or not the received marking signal is a signal corresponding to a specific reflection face among the reflection faces of the polygon mirror.

An optical writing device includes: an image carrier; an exposer that exposes a curved surface of the image carrier; and a control circuit that controls the exposer, wherein the exposer includes a plurality of light-emitting element groups having different positional relationships from one another with the image carrier, and has a configuration that is adjusted in accordance with at least one of an angle at which light reaching the curved surface of the image carrier from each light-emitting element group enters the image carrier, and a distance of each light-emitting element group from the image carrier.

A holding member includes a first opposing portion (first inner wall surface) and a second opposing portion (second inner wall surface) which oppose side wall surfaces of a lens array. Side wall surfaces of the lens array on opposite end sides with respect to a longitudinal direction of the lens array are exposed from opposite ends of the first opposing portion and opposite ends of the second opposing portion.

A mirror device includes a mirror, a base member, a fixing unit, a biasing mechanism, and a movement mechanism. The mirror has an elongated shape including a reflective surface. The base member has an elongated shape disposed on a back side opposite to the reflective surface. The fixing unit fixes a portion of the mirror excluding the reflective surface to both ends of the base member in a lengthwise direction. The biasing mechanism is disposed on the back side of the mirror and biases the mirror towards the base member. The movement mechanism is disposed on the back side of the mirror and moves the mirror in a direction away from the base member.

Provided is an optical scanning unit including a light source configured to emit a laser beam, a deflector configured to deflect the laser beam, a lens through which the laser beam is to pass, and a frame housing the deflector and the lens. The frame includes a laser transmissive portion allowing transmission of the laser beam for emission of the laser beam outward from the optical scanning unit and an adjacent portion adjacent to the laser transmissive portion. The laser transmissive portion and the adjacent portion are integrally formed of resin. The laser transmissive portion and the adjacent portion alternatively each include identical resin.

An optical scanning device includes light sources, a deflector deflecting light beams emitted from the light sources, a first lens transmitting the light beams deflected by the defector, and second lenses guiding the light beams transmitted from the first lens to respective surfaces to be scanned. The second lenses are arranged so that a first incident position of a first light beam emitted by a first light source and entering one of the second lenses is closer to the respective surface to be scanned along an optical axis of the first lens than a second incident position of a second light beam emitted by a second light source and entering another of the second lenses, and an incident angle of the second light beam with respect to the optical axis along a deflection direction by the deflector is greater than the incident angle of the first light beam.

An exposure apparatus includes: light source substrates on which light sources aligned in a first direction are aligned in rows and formed on a formation surface; an optical element that causes light emitted from the light sources to form an image on a surface of an image carrier that has a cylindrical shape and rotates with a rotational symmetry axis parallel to the first direction; a microlens array in which the optical elements aligned in the first direction are aligned in rows; and a holder that holds the light source substrates, wherein in each of the light source substrates, at least two of the light sources are formed at different positions in a second direction intersecting with the first direction and being parallel to the formation surface, and the holder holds the light source substrates to cause the formation surfaces of the light source substrates to cross each other.