Light-emitting device, exposure device, image forming apparatus and light-emission control method

An exposure device comprising:

• a light-emitting element chip including a substrate, and a light-emitting element array having a plurality of light-emitting elements arrayed in a line in a fast scan direction on the substrate, the light-emitting element array having:
• a first light-emitting element group including light-emitting elements arrayed in a center portion in the fast scan direction;
• a second light-emitting element group including light-emitting elements arrayed from one end side of the first light-emitting element group in the fast scan direction;
• and
• a third light-emitting element group including light-emitting elements arrayed from the other end side of the first light-emitting element group in the fast scan direction;
• a mounting member to which a plurality of the light-emitting element chips are mounted in a zigzag pattern to form an overlapping portion in a borderline region between each adjacent two light-emitting chips, the overlapping portion including the second light-emitting element group in one of the adjacent two light-emitting chips and the third light-emitting element group of the other one of the adjacent two light-emitting chips overlapping with each other in the fast scan direction;
• a supply section that supplies a light-emission signal to each of the plurality of light-emitting element chips, the light-emission signal setting, as luminous targets, light-emitting elements being consecutive in the fast scan direction, and being less than the plurality of light-emitting elements constituting the light-emitting element array;
• a correcting section that corrects at least any one of positions and the number of the light-emitting elements set as the luminous targets in each of the plurality of light-emitting element chips;
• and
• an optical member that focuses light emitted by the plurality of light-emitting element chips onto an image carrier.

An image forming apparatus comprising a plurality of image forming parts each including:

• an image carrier,
• a charging device that charges the image carrier,
• an exposure device that exposes the image carrier charged by the charging device to form an electrostatic latent image on the image carrier, the exposure device including:
• a light-emitting element array that has a plurality of light-emitting elements arrayed in a line at intervals corresponding to a first resolution;
• a supply unit that supplies a light-emission signal corresponding to a second resolution, the second resolution being 1/m of the first resolution, where m is an integer not less than 2;
• a setting unit that divides the plurality of light-emitting elements into a plurality of sets each including m continuous light-emitting elements in the light-emitting element array, and that sets whether to cause the m continuous light-emitting elements, which are included in each of the plurality of sets, to emit light on a single set basis by using the light-emission signal supplied from the supply unit;
• and
• a correcting unit that corrects the division of the plurality of light-emitting elements in the light-emitting element array performed by the setting unit, on a single light-emitting element basis;
• a developing device that develops the electrostatic latent image formed on the image carrier to form an image on the image carrier;
• and
• a transfer device that transfers the image formed on the image carrier onto a recording medium.

A light-emission control method of a light-emitting device including a light-emitting element array that has a plurality of light-emitting elements arrayed in a line at intervals corresponding to a first resolution;

• the light-emission control method comprising:
• supplying a light-emission signal corresponding to a second resolution, the second resolution being 1/m of the first resolution, where m is an integer not less than 2;
• dividing the plurality of light-emitting elements into a plurality of sets each including m continuous light-emitting elements in the light-emitting element array, and setting whether to cause the m continuous light-emitting elements, which are included in each of the plurality of sets, to emit light on a single set basis by using the light-emission signal;
• and
• correcting the division of the plurality of light-emitting elements in the light-emitting element array, on a single light-emitting element basis.