According to an embodiment, a signal generation circuit includes a generation unit configured to generate a second clock signal from division of a first clock signal and generate a timing signal with a cycle length that is a sum of a predetermined number of half-cycle periods of the second clock signal. A period changing unit of the signal generation circuit is configured to adjust the cycle length of the timing signal by changing a length of at least one half-cycle period of the second clock signal. An output unit of the signal generation circuit is configured to output the second clock signal and the timing signal.

An optical scanning device includes a housing and an fθ lens accommodated in the housing. The housing has a bottom surface, and side walls erected from a bottom surface and surrounding the bottom surface along a perimeter thereof. One side wall of the side walls has, on an outer surface thereof, one or more positioners that position the optical scanning device relative to an image forming apparatus main body. The bottom surface has one or more first bottom surface ribs extending from the positioners toward the fθ lens in an oblique direction with respect to the side wall having the positioners in a plan view.

A scanning optical device includes a deflector, a reflecting mirror, a housing to accommodate the deflector and the mirror; and an elastic member to urge the mirror toward the housing. The mirror includes a first surface urged by the elastic member, a second surface opposite to the first surface, a third surface and a fourth surface perpendicular to the first and second surfaces. The housing includes a bearing surface to support the second surface and a regulating portion to regulate movement of the mirror to a mirror widthwise direction, perpendicular to a mirror longitudinal direction and parallel with the second surface, and toward an opening of the housing. The regulating portion is provided opposite to only a part of the third surface so that a ridge line of the mirror between the second surface and the third surface does not contact the regulating member even an attitude of the mirror changes in a direction away from the bearing surface.

A light-emitting device includes a base that extends in one direction; a light-emitting unit in which multiple light sources that are disposed in the one direction are supported by a supporting body that extends in the one direction and that is formed from a metal block; a spacer that is interposed between the base and the light-emitting unit in a direction of an optical axis of each light source; and a fixing unit that fixes the light-emitting unit to the base in a mode in which a compressive load is applied to the spacer.

An optical scanning device includes a light source, a beam detector that takes a main scanning start time of a light beam emitted from the light source and deflection-scanned in a predetermined main scanning direction by a deflection-scanning component, and a housing with a support portion that supports reflecting mirrors in different arrangement positions so arrangement angles are different from each other. The support portion includes a first support portion that supports a first side surface of the reflecting mirror in a plurality of arrangement positions. A second support portion supports the first side surface of the mirror with the first support portion, causing a first arrangement angle in the first arrangement position of the reflecting mirror. A third support portion supports the first side surface of the reflecting mirror with the first support portion, causing a second arrangement angle in a second arrangement position of the reflecting mirror.

An image forming apparatus includes a photoconductor, a light source, and circuitry that receives: first image data including first pixels each indicating image density or one of turning on and off the light source; and tag data indicating an attribute of each first pixels. The circuitry sets specific data to identify a first target pixel subjected to change out of the first pixels, converts the first image data into second image data having a higher resolution than that of the first image data, and controls the light source according to the second image data to form an image. In conversion, the circuitry identifies a second target pixel corresponding to the first target pixel out of second pixels of the second image data according to the specific data and the tag data, and changes the second target pixel into a pixel to turn on the light source.

An optical scanning device includes a cooling air passage that passes through inside of the housing, a blowing part that takes in air outside of the housing from a first end portion of the cooling air passage and allowing the air to be discharged from a second side portion, the first end portion facing the second side portion, a foreign matter falling concave part provided adjacent to the transparent cover in the predetermined direction such that an accumulated foreign matter is fallen at a front side in a progress direction of the cleaning member when the cleaning member reaches each moving end of the reciprocal movement path, and a communication passage that allows the foreign matter falling concave part and the cooling air passage to communicate with each other.

In an image-forming apparatus, an optical scanning device that is adjustable in a turn available manner around a turn axis line parallel to an axis line orthogonal to a main scanning direction of a light beam is attached to an image-forming apparatus body. The image-forming apparatus body has a shaft support that supports the optical scanning device in a turn available manner around a turn axis line and a holder facing a housing at a position different from that of the shaft support. The optical scanning device is held by the image-forming apparatus body in a state in which an elastic member is sandwiched between the housing and the holder in a pressed manner.

An image reading apparatus includes an image reading unit, a mounting portion, and a cover member. The cover member includes a first restricting portion, a lock portion, and an operation portion. The operation portion operated from outside the main unit is displaceable in a direction in which the lock portion deforms from the locking shape into the releasing shape. The mounting portion includes a second restricting portion and a part. The second restricting portion restricts displacement of the operation portion in the cover member mounted on the mounting portion in the second orientation. The part has a second aperture opening into the lock portion in the cover member mounted on the mounting portion in the second orientation from outside the main unit. The second aperture is an opening for the insertion of a tool for deforming the lock portion from the locking shape into the releasing shape.

An image forming apparatus which forms an image on a medium on the basis of an input image signal includes: an image carrier configured to carry a developed toner image transferred to the medium on a photoreceptor layer; a contact member arranged so as to be in contact with the surface of the photoreceptor layer; a trace pattern generating unit configured to generate a trace pattern indicating specific information on the image forming apparatus; a composition unit configured to add the trace pattern to the image signal; and an acquiring unit configured to acquire information on the thickness of the photoreceptor layer of the image carrier, wherein the trace pattern is used for arranging a plurality of image areas at respective positions, and the trace pattern generating unit is configured to generate the trace pattern with the image area whose size is reduced in accordance with reduction of the thickness of the photoreceptor layer.