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 scanning device includes a laser light emitter in which an excess of a current over a bias current is increased or decreased in proportion to an analog signal input thereto, a laser driver to drive the laser light emitter, an optical scanner to scan a surface of an object with laser light emitted from the laser light emitter, an offset value determiner to determine an offset value of the analog signal input to the laser light emitter based on a target light quantity of the laser light emitter, and a laser driver controller to control a quantity of light emitted from the laser light emitter by inputting a signal on the basis of a signal of the determined offset value to the laser driver.

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.

Examples described herein relate to a system consistent with the disclosure. For instance, the system may comprise a printing device including hardware to form an image on a print medium, a memory resource, and a controller to receive a print job to form the markings on the print medium, designate a pixel of the received print job to form a covert dot pattern on the markings, where the pixel corresponds to a first laser intensity level; and adjust a laser intensity of the printing device to a second laser intensity level based on the first laser intensity level of the designated pixel to form the covert dot pattern.

An optical element includes an optical surface for giving an optical effect to a light beam that passes therethrough. The optical surface includes a first region and a second region. The first region and the second region are smoothly continuous with each other. The optical surface has an absolute value of a maximum curvature at a boundary between the first region and the second region. The absolute value of the maximum curvature is smaller than a predetermined value.

Optical scanner and electrophotographic image forming apparatus are provided. The optical scanner includes a light source, configured to emit a light beam; an optical deflector, configured to deflect the light beam emitted from the light source; a first optical unit, arranged there-between and including a refraction unit and a diffraction unit; and a second optical unit, arranged in a light exit direction of the optical deflector and configured to make the light beam deflected by the optical deflector form an image on a scanning target surface. A range of a ratio of a refractive power Φ.sub.r to a diffractive power Φ.sub.d of the first optical unit in a main scanning direction is 0.3<Φ.sub.r/Φ.sub.d<0.5; and a range of a ratio of a refractive power Φ.sub.s to a diffractive power Φ.sub.n of the first optical unit in a sub scanning direction is 0.7<Φ.sub.s/Φ.sub.n<1.0.

Optical scanner and electrophotographic image forming apparatus are provided. The optical scanner includes a light source, configured to emit a light beam; an optical deflector, configured to deflect the light beam emitted from the light source; a first optical unit, arranged there-between and including a refraction unit and a diffraction unit; and a second optical unit, arranged in a light exit direction of the optical deflector and configured to make the light beam deflected by the optical deflector form an image on a scanning target surface. A range of a ratio of a refractive power Φ.sub.r to a diffractive power Φ.sub.d of the first optical unit in a main scanning direction is 0.3<Φ.sub.r/Φ.sub.d<0.5; and a range of a ratio of a refractive power Φ.sub.s to a diffractive power Φ.sub.n of the first optical unit in a sub scanning direction is 0.7<Φ.sub.s/Φ.sub.n<1.0.

An article includes a body member and a detachable member detachably attached to the body member. One of the body member and the detachable member includes a cover portion having an engaging portion on an inner wall face of the cover portion. The other includes a covered portion that is covered with the cover portion and has an engaged portion on an outer wall face of the covered portion. The engaging portion and the engaged portion are configured to be disengaged by warping the cover portion so that the cover portion displaces to an outer wall face side of the cover portion. The one of the body member and the detachable member includes a finger-applying-position indicator at a position deviated from a portion corresponding to the cover portion, on an outer wall face of the one. The finger-applying-position indicator indicates a position to be applied with fingers of a user.

Provided is a light source device including a plurality of light emitting points arranged in matrix within a first cross section parallel to a first direction and a second direction. When light emitting points are projected within a second cross section parallel to first direction and a third direction perpendicular to first cross section, light emitting points have equal intervals between projections adjacent to each other. When light emitting points are projected within a third cross section parallel to second and third directions, light emitting points have equal intervals between projections adjacent to each other. An interval between light emitting points adjacent to each other in a row of matrix, an interval between light emitting points adjacent to each other in a column of matrix, an angle between row and column, an angle between column and first direction, and an angle between row and second direction are appropriately set.

A controller which causes a light emitting element to continuously perform minute emission for a plurality of dots in a level in which toner is not attached to a non-image section on an image bearing member is provided. The controller controls a first driving current for an image section and controls a second driving current used to perform the minute emission by the light emitting element in the non-image section several times in one job. In the image section, a driving current obtained by adding the first driving current to the second driving current is supplied so that the light emitting element emits light.