A natural frequency measuring device includes a receiving unit and a measuring unit. The receiving unit receives information of an image formed on a recording medium with vibrations of different frequencies provided to a member used to form the image. The measuring unit measures a natural frequency of the member from a frequency response characteristic using a misregistration amount of the image represented by the information of the image received by the receiving unit.

An image forming apparatus includes a scanner unit configured to emit light depending on image information, the scanner unit including an optical element and an optical box provided with an opening and configured to accommodate the optical element; and an outer cover of the image forming apparatus. The optical box has an open portion uncovering the optical element. The open portion of the optical box faces the outer cover.

An image forming apparatus includes a rotatable image bearer, an exposure device, a development unit, an adjuster, and a magnetic member. The exposure device forms a latent image on a surface of the image bearer. The developing unit renders the latent image visible with developer including toner and carrier. The adjuster contacts each of the image bearer and the exposure device to regulate a distance between the image bearer and the exposure device. The magnetic member is arranged side by side with the adjuster in a direction of rotation of the image bearer.

A lens unit according to an embodiment includes: a lens array that includes lens elements each provided with an optical axis and extends in a first direction; a support member that supports the lens array; and an adhesive that bonds the lens array and the support member. The support member includes a first adhesive holding portion with a specified depth in a direction of the optical axis and a second adhesive holding portion shallower than the first adhesive holding portion. The first adhesive holding portion and the second adhesive holding portion are aligned in the first direction. The adhesive is arranged at the first adhesive holding portion and the second adhesive holding portion.

A light beam scanning device deflecting, by using a rotating polygon mirror, a light beam emitted from a light source and condensing, by using a scanning lens, the deflected light beam onto a scanned surface. The light beam scanning device includes: a base made of a metal or a resin; a motor unit attached to the base and rotating the polygon mirror; a holding member holding the scanning lens; and one or more fixing members disposed between the base and the holding member, fixing the holding member to the base with the scanning lens spaced away from the base. In the light beam scanning device, the base has, between at least one of the fixing members and the motor unit, a penetrating hole or groove around which heat transmitted from the motor unit through the base to the fixing member passes.

An image forming apparatus includes a control unit: starting up a rotary polygon mirror based on a first signal output by a driving unit thereof; causing a light source to emit a laser-beam while controlling a rotational speed of the rotary polygon mirror based on the first signal to acquire a second signal output from a detecting unit of the laser-beam; turning off the light source after acquiring a phase relation between the first and second signals; causing a charging unit to charge a photosensitive member; making the laser-beam to enter onto the detecting unit without exposing the photosensitive member based on the phase relation in response to the rotational speed reaching a target speed; controlling the rotational speed based on the second signal in response to the laser-beam being entered; and starting image formation in response to the rotational speed converging within a predetermined range including the target speed.

An image reading apparatus includes a light guide including a light guide portion configured to guide light emitted from a plurality of light sources, a deflection portion configured to deflect and emit light guided by the light guide portion, and a projection portion. The light guide portion includes a first surface and a second surface configured to internally reflect the light from the light sources. At least one of the first surface and the second surface includes a concave portion positioned to cover the projection portion in the arrangement direction. In a plane passing through the concave portion and parallel to the arrangement direction, a distance between the first surface and the second surface in a portion where the concave portion is formed is smaller than a distance between the first surface and the second surface in a portion where the concave portion is not formed.

An image forming apparatus includes an image former configured to print on a printing paper a plurality of lines that are arranged at predetermined intervals in a main scanning direction and are vertical to the main scanning direction using different photosensitive drums, a scanner configured to scan the printing paper on which the plurality of lines are printed, and at least one processor configured to perform color registration correction using the plurality of scanned image

An image forming apparatus, including: a cartridge including a photosensitive drum and a regulation portion; a light emitting device configured to emit light from a light emission surface to the photosensitive drum; and a movement unit configured to reciprocate the light emitting device between an exposure position and a retracted position, wherein the regulation portion regulates a cleaning member, which includes a cleaning portion configured to rub and clean the light emission surface by a sliding movement of the cleaning member on the light emission surface of the light emitting device positioned at the retracted position so as to prevent the cleaning member from contacting the photosensitive drum and so as to bias the cleaning portion to prevent the cleaning portion from being separated from the light emission surface during the sliding movement of the cleaning member.

An exposure window component is provided so as to be separated from an exposure device housing and is attached to an opening through which light from the exposure device housing passes. The exposure window component includes: a transmitting member that allows light from the exposure device housing to pass therethrough; a holding frame that holds the transmitting member; a receiving member that is provided at a periphery of the opening to receive the holding frame when the transmitting member is attached and that removably supports the transmitting member; and a grasping part that is provided at a portion of the holding frame and is grasped when the transmitting member is attached and removed.