An optical writing device having; a plurality of light-emitting points; a photodiode configured to output a signal which represents a quantity of incident light from a predetermined light-emitting point selected from the plurality of light-emitting points; and a calculation section for calculating a temperature of the photodiode based on a magnitude of a photodiode dark current included in the signal output from the photodiode while the predetermined light-emitting point is OFF.

An image forming apparatus includes: a photoconductor that rotates about a first axis; an exposure portion that includes a substrate that includes a plurality of light emitting portions for exposing a surface of the photoconductor, and a support portion for supporting the substrate, and that moves between an exposure position where the photoconductor is exposed and a retracted position where the photoconductor is retracted from the exposure position; and a rotational member that has a second axis along the first axis, and that moves the exposure portion between the retracted position and the exposure position by rotation about the second axis.

An image forming apparatus includes: a photoconductor that rotates about a first axis; an exposure portion that includes a substrate that includes a plurality of light emitting portions for exposing a surface of the photoconductor, and a support portion for supporting the substrate, and that moves between an exposure position where the photoconductor is exposed and a retracted position where the photoconductor is retracted from the exposure position; and a rotational member that has a second axis along the first axis, and that moves the exposure portion between the retracted position and the exposure position by rotation about the second axis.

According to an aspect of the present invention, a light-emitting chip includes: a plurality of light-emitting portions and a drive circuit. The drive circuit includes: first to fourth transferring unit, a first switch configured to switch between a first state in which start signals output by the fourth and third transferring units are output to the second and first transferring unit, respectively, and a second state in which the start signal output by the fourth and the third transferring units are output to the third and second transferring unit, respectively, and a second switch configured to switch between a third state in which the first and third transferring units and the first signal line are connected, and a fourth state in which the first and third transferring units and a second signal line are connected.

The image forming apparatus includes an exposure head. The exposure head includes an organic EL element array and a rod lens array, and forms an image on a photosensitive drum by irradiating light emitted from each organic EL element on the photoreceptor via each rod lens. In the exposure head, light emitting from the organic EL element is controlled by a controller. The controller generates a filter coefficient for correcting a spot shape based on the difference between the spot shape of the light spot on the photosensitive drum and the target spot shape on the photosensitive drum. It is noted that the difference is generated by the deviation between the distance from the organic EL element to the photosensitive drum, and the correct focus position.

Systems and methods for printing data on a substrate including a color-changeable material are provided. One system includes a processing circuit and a device including an energy source. At least a portion of a printed publication is printed on the substrate using a commercial printing press based on fixed data. The device including the energy source is configured to add variable data to the substrate. The processing circuit is configured to receive the variable data and to control the energy source to change a color of the color-changeable material based on the variable data to provide at least a portion of the printed publication. The processing circuit is configured to control the energy source to change the color of the color-changeable material in-line with a flow of the substrate through one of a printing line, a finishing line, or a packaging line of the commercial printing press.

An image forming apparatus having front and rear surfaces, a photoreceptor having a rotation axis extending in a first direction, an exposure unit, and a cooling unit. The exposure unit includes a substrate having a longitudinal axis extending in the first direction, a first surface and a second surface. A plurality of light emitting elements that emit light toward the photoreceptor are mounted on the first surface of the substrate. The cooling unit includes an intake port that sucks air from outside of the image forming apparatus. The intake port is disposed at an intake port distance in the first direction to the rear surface. The intake port distance is shorter than a distance in the first direction of a center of the substrate to the rear surface. The cooling unit cools the substrate by blowing air sucked by the intake port onto the second surface of the substrate.

According to an aspect of the present invention, a light-emitting chip includes: a plurality of light-emitting portions and a drive circuit. The drive circuit includes: first to fourth transferring unit, a first switch configured to switch between a first state in which start signals output by the fourth and third transferring units are output to the second and first transferring unit, respectively, and a second state in which the start signal output by the fourth and the third transferring units are output to the third and second transferring unit, respectively, and a second switch configured to switch between a third state in which the first and third transferring units and the first signal line are connected, and a fourth state in which the first and third transferring units and a second signal line are connected.

An image forming apparatus having front and rear surfaces, a photoreceptor having a rotation axis extending in a first direction, an exposure unit, and a cooling unit. The exposure unit includes a substrate having a longitudinal axis extending in the first direction, a first surface and a second surface. A plurality of light emitting elements that emit light toward the photoreceptor are mounted on the first surface of the substrate. The cooling unit includes an intake port that sucks air from outside of the image forming apparatus. The intake port is disposed at an intake port distance in the first direction to the rear surface. The intake port distance is shorter than a distance in the first direction of a center of the substrate to the rear surface. The cooling unit cools the substrate by blowing air sucked by the intake port onto the second surface of the substrate.