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.

There is provided an organic compound represented by formula [1-1] or [1-2]:

##STR00001##

where R.sub.1 to R.sub.20 are each independently selected from a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an amino group, an aromatic hydrocarbon group, a heterocyclic group, an aryloxy group, a silyl group, and a cyano group, in which at least one of R.sub.1 to R.sub.4 and R.sub.6 to R.sub.9 and at least one of R.sub.11 to R.sub.14 and R.sub.16 to R.sub.19 are amino groups; and X.sub.1 to X.sub.4 are each oxygen, sulfur, selenium, or tellurium and are optionally the same or different.

An image forming apparatus includes a housing having an opening, a cover movable between an open position and a closed position, a first photoconductive drum and a second photoconductive drum, a first exposing head having a first boss and rotatably coupled to the cover, a second exposing head having a second boss and rotatably coupled to the cover, and a cam rotatably coupled to each of the first exposing head and the second exposing head. The cam is configured to rotate each of the first exposing head and the second exposing head. The cam includes (i) a first elongated hole into which the first boss fits and extending a direction intersecting a movement direction in which the cam moves and (ii) a second elongated hole into which the second boss fits and extending in a direction intersecting the movement direction of the cam.

A hierarchical printhead design supports multiple print modes. A first print mode uses a first subset of light sources having a first spacing. A second print mode uses a second subset of light sources having a second spacing which is less than the first spacing. Image data for lines of image data are sequentially loaded into the printhead, wherein if the specified print mode is the first print mode, image data for a first group of light sources corresponding to the first subset are loaded, and if the specified print mode is the second print mode, image data for the first group of light sources are first loaded, and then image data for a second group of light sources corresponding to the light sources in the second subset that are not in the first subset are loaded.

A light emitting device includes a first light-emitting-element row that includes light emitting elements arranged in a row in a main scanning direction and a second light-emitting-element row that includes light emitting elements arranged in a row in the main scanning direction and that is positioned in such a manner that at least a portion of the second light-emitting-element row overlaps the first light-emitting-element row in a subscanning direction. The first light-emitting-element row and the second light-emitting-element row are each formed by arranging light-emitting-element array chips in each of which the light emitting elements are arranged in a row in the main scanning direction. In each of the light-emitting-element array chips, a pitch of the light emitting elements arranged in a row is changed from a first pitch to a second pitch, which is different from the first pitch, in a central region of the row of the light emitting elements.

An optical head comprises a substrate on which optical elements are arranged in a main scanning direction, a lens unit that transmits light emitted from the optical elements or light entering the optical elements, and a holder that holds the lens unit. The holder has a sidewall extending in the main scanning direction. The sidewall has a hole at a position facing the lens unit. A fixing member is provided in the hole. The fixing member fixes the lens unit to the sidewall.

A driving device is provided. The driving device includes a plurality of load blocks each including a load element, a plurality of driving circuits configured to drive the plurality of load blocks, and a connection circuit configured to connect the plurality of load blocks to the plurality of driving circuits, respectively. The connection circuit is configured to switch a connection combination of each of the plurality of load blocks and each of the plurality of driving circuits.

An image forming including: a photoconductor; an exposure unit including a substrate provided with a plurality of light emitting portions configured to emit light to expose the photoconductor, and a first duct configured to guide an airflow that cools the substrate from one side to another side in a longitudinal direction of the substrate along the substrate; an IC mounted on the substrate; a fan configured to generate an airflow that cools the substrate; and a second duct configured to communicate with the first duct through a first opening portion, and guide the airflow generated by the fan, the first opening portion is located on the one side with respect to the center of the substrate in the longitudinal direction of the substrate, and the IC is located between the center of the substrate in the longitudinal direction and the first opening portion.

A cleaning rod includes a rod-like member, a slidable portion which is provided on a free end side of the rod-like member with respect to a direction in which the cleaning rod is inserted and which is slidable on a light emergent surface of a lens of an image forming apparatus, and a restricting portion configured to restrict movement of the slidable portion in a direction away from the light emergent surface with respect to an optical axis direction by contacting the holder at each of free ends of opposing wall portions of a holder of the image forming apparatus from a side opposite from a side where a photosensitive member of the image forming apparatus is provided with respect to the optical axis direction in a state in which the slidable portion contacts the light emergent surface.

An exposure head for forming an image of a first resolution corresponding to an arrangement interval of a plurality of lower electrodes in a crossing direction or an image of a second resolution lower than the first resolution. A circuit portion includes an image data storage portion that is arranged on the substrate together with a plurality of lower electrodes and converts input image data into image data according to the resolution. By this, the same exposure head can be used for both high resolution images and low resolution images without degrading the image quality.