A light emitting device 401 includes a silicon substrate and a light emitting region including a lower electrode, a light emitting layer, and an upper electrode, and an exposure head is provided with a printed board on which light emitting devices 401 are arranged in a staggered form and a circuit portion 602 for controlling, on the basis of image data, a voltage of each of electrodes included in the lower electrode so that the light emitting device layer emits light and is for forming an image with a resolution corresponding to an arrangement interval of the lower electrode with respect to a crossing direction, and the circuit portion 602 is disposed together with the light emitting region on the silicon substrate. Costs on wire bonding and an area of a wiring board can be suppressed.

A light emitting device includes: a base that extends in one direction; plural light emitters that are disposed on a front surface side of the base so as to be displaced from each other in a direction intersecting the one direction and in each of which plural light sources that are arranged in the one direction are supported by a support that extends in the one direction; and a substrate that is provided so as to extend in the one direction on an inner side portion of each of the plural light emitters in the direction intersecting the one direction of the base and that drives the light emitter.

The print head and light emitting elements, first and second drive circuits, and a control circuit. The light emitting elements and drive circuits are spaced from each other an arrangement pitch. The first drive circuit includes a first capacitor and sets a light emission level for the first light emitting element. The second drive circuit includes a second capacitor and sets a light emission level of the second light emitting element. The control circuit is connected to the first drive circuit by a first wiring and to the second drive circuit by a second wiring and controls voltages across the first and second capacitors individually. A difference between the length of the first wiring and the length of the second wiring is less than the arrangement pitch.

In an image forming apparatus, a CPU 73 can perform a normal mode and a low mode in which a photoconductive drum 1 rotates at a rate m/n times the rotational rate in the normal mode, lower than the rotational rate in the normal mode. In the low mode, the CPU 73 causes a synchronizing signal generation portion 74 to generate a line synchronizing signal at a cycle 1/m times the cycle of the line synchronizing signal generated in the normal mode, and causes a chip data conversion portion 72 to transmit, to an exposure head 6, the same image data signal m times and transmit, to the exposure head 6, an image data signal that brings a light-emitting portion 50 into no light emission n-m times, in synchronization with n number of line synchronizing signals.

A substrate on which a plurality of light emitting elements is mounted; a lens configured to condense light emitted from the light emitting elements on a photoreceptor; a holding member configured to hold the substrate and the lens; and an attachment portion configured to be provided on the holding member, provided outside an end portion of the substrate in a longitudinal direction of the substrate, and provided with a moving mechanism that moves the holding member to an exposure position at which the photoreceptor is exposed and a separation position at which the holding member is separated from the photoreceptor with respect to the exposure position are included, in which a wall portion is provided between the end portion of the substrate and the attachment portion in the longitudinal direction, and a sealing material is applied so as to be in contact with the substrate and the wall portion.

An image forming apparatus includes a photosensitive member that is rotatable, a substrate, a lens array, a holder, and a conductive member provided on the holder. The substrate includes a plurality of light-emitting elements, a driver integrated circuit (IC), and a wiring pattern. The plurality of light-emitting elements is arrayed in a rotational axis direction of the photosensitive member to emit light to which a surface of the photosensitive member is exposed. The driver IC drives the plurality of light-emitting elements. The wiring pattern includes a supply line that supplies power to the driver IC and a ground wire that grounds the driver IC. The lens array collects the light emitted from the plurality of light-emitting elements on the photosensitive member. The holder holds the substrate and the lens array, is grounded, and is made of metal. The conductive member electrically connects the holder and the ground wire.

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.

A light-emitting device includes a base that is composed of a metal block that extends in a first direction, multiple light-emitting portions unaligned in the first direction and facing a front surface of the base, the multiple light-emitting portions including multiple light sources that extend in the first direction and that are supported by a support that extends in the first direction, and a handle that is formed below the front surface of the base and that is to be held by an operator with the base placed on a flat surface.

An image forming apparatus, having a photosensitive drum assembly, an exposure head, and a bearing, is provided. The photosensitive drum assembly includes a photosensitive drum and a flange disposed at an end of the photosensitive drum in an axial direction of an axis of the photosensitive drum. The flange contacts an inner surface of the photosensitive drum. The exposure head includes a plurality of light emitters aligned along the axial direction of the photosensitive drum, a lens array focusing light from the light emitters on the photosensitive drum, and a head frame to support the light emitters and the lens array. The bearing has a first contact face to contact the exposure head to define a distance between the lens array and the photosensitive drum along a direction of an optical axis of the light.

An image forming apparatus includes a photoreceptor; an image signal generating unit configured to generate an image signal based on input image data; a light emitting portion configured to emit light based on the image signal and expose the photoreceptor; a driving unit configured to drive the light emitting portion; a first substrate in which the driving unit is provided and a plurality of the light emitting portions is provided in a direction parallel to a rotational axis direction of the photoreceptor; an exposure head including the first substrate; a reference clock signal generating unit configured to generate a reference clock signal that is a clock signal of a constant frequency; a modulated clock signal generating unit configured to generate a modulated clock signal by performing spread spectrum on the reference clock signal, the modulated clock signal being a composite wave in which odd-order harmonics are combined with a fundamental wave when a triangular wave is subjected to Fourier series expansion; a transmission unit configured to superimpose the modulated clock signal on the image signal and transmit the superimposed signal to the first substrate; a second substrate on which the image signal generating unit, the modulated clock signal generating unit, and the transmission unit are provided; and an extraction circuit that is mounted on the first substrate and extracts the modulated clock signal from the superimposed signal transmitted from the transmission unit.