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 electrophotographic photosensitive member includes a conductive substrate and a photosensitive layer. The photosensitive layer is a single layer, and contains a charge generating material, an electron transport material, a binder resin, and a hole transport material.

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The electron transport material includes a compound represented by general formula (1). The binder resin includes a polycarbonate resin having an end group and a main chain represented by general formula (10).

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 exposure apparatus includes: a substrate that extends in a longitudinal direction intersecting with a gravity direction and has light emitting elements emitting light toward a gravity direction; a housing that extends in the longitudinal direction, to which the substrate is attached; a support section that supports both end side portions of the housing in the longitudinal direction against gravity; and a structure section having a weight that is attached to an intermediate portion of the housing in the longitudinal direction and supported by the support section in the gravity direction.

An image forming apparatus includes a photoconductor, a light emitting substrate, and imaging optical systems, wherein an optical axis of the imaging optical systems are parallel, imaging magnifications of the imaging optical systems are substantially equal for the light emitting point groups, the imaging optical systems includes a first lens array, a second lens array, and apertures, central points of the light emitting point group exist in a first plane, central points of the imaging lenses exist in a second plane, central points of the apertures exist in a third plane, central points of the imaging lenses exist in a fourth plane, the first plane forms a non-zero predetermined angle with respect to a plane perpendicular to an optical axis direction, and the angle formed with respect to the plane perpendicular to the optical axis direction is greater in the order of the first, second, third, and the fourth plane.

An exposure apparatus includes: a substrate that, extends in a longitudinal direction intersecting with a gravity direction and has light emitting elements emitting light, toward a gravity direction; a housing that extends in the longitudinal direction, to which the substrate is attached; a support section that supports both end side portions of the housing in the longitudinal direction against gravity; and a structure section having a weight that is attached to an intermediate portion of the housing in the longitudinal direction and supported by the support section in the gravity direction.

An optical scanning apparatus includes first and second deflecting units, and first and second imaging optical systems to guide first and second light fluxes deflected by the first and second deflecting units to first and second scanned surfaces. The first and second imaging optical systems include first and second imaging elements having the largest refractive power in a sub-scanning section. A distance on an optical path between the first deflecting unit and the first imaging element is shorter than that between the second deflecting unit and the second imaging element. The optical scanning apparatus satisfies: $-\frac{d_2}{N_2}\frac{{}_{21}}{{}_2}<-\frac{d_1}{N_1}\frac{{}_{11}}{{}_1},$
where N.sub.1, d.sub.1, .sub.1, and .sub.11 are a refractive index, a thickness on an optical axis, a refractive power in a sub-scanning section, and a refractive power in the sub-scanning section of an incident surface, of the first imaging element, and N.sub.2, d.sub.2, .sub.2, and .sub.21 are equivalents of the second imaging element.

An exposure device according to an embodiment may include: a holding member provided with a reference surface; an optical system being in contact with the reference surface and slidable in a first direction parallel to the reference surface; and a board including a light emitting element and being fixed to the holding member such that the optical system is sandwiched between the reference surface and the board.

In an image forming apparatus, if a path for transferring heat generated by a drive integrated circuit to a frame (a heat dissipation plate) of an apparatus main body has a point that divides the path, foreign matter such as dirt and dust can be caught at the point, so that heat dissipation efficiency can decrease due to presence of such foreign matter. Therefore, a configuration is provided in which a drive integrated circuit and a frame (a heat dissipation plate) provided in a cover are connected by a heat transfer member, so that a heat transfer path from the drive integrated circuit to the frame has no point that divides the path.

An image forming apparatus includes a photoconductor, a light emitting substrate, and imaging optical systems, wherein an optical axis of the imaging optical systems are parallel, imaging magnifications of the imaging optical systems are substantially equal for the light emitting point groups, the imaging optical systems includes a first lens array, a second lens array, and apertures, central points of the light emitting point group exist in a first plane, central points of the imaging lenses exist in a second plane, central points of the apertures exist in a third plane, central points of the imaging lenses exist in a fourth plane, the first plane forms a non-zero predetermined angle with respect to a plane perpendicular to an optical axis direction, and the angle formed with respect to the plane perpendicular to the optical axis direction is greater in the order of the first, second, third, and the fourth plane.