Light-emitting device, driving method of light-emitting device, print head and image forming apparatus

A driving method of a light-emitting device including a plurality of light-emitting chips that each include a plurality of light-emitting elements and a plurality of memory elements provided respectively corresponding to the plurality of light-emitting elements, each of the memory elements memorizing a corresponding light-emitting element to be caused to light up, each of the plurality of light-emitting chips being capable of lighting up the light-emitting elements more than one, in parallel;

• the driving method comprising:
• transmitting an enable signal in common to light-emitting chips belonging to each of M groups into which the plurality of light-emitting chips are divided, where M is an integer more than one, the enable signal enabling selection of light-emitting elements to be caused to light up among the plurality of light-emitting elements;
• transmitting a write signal in common to light-emitting chips belonging to each of N classes into which the plurality of light-emitting chips are divided, where N is an integer more than one, the write signal setting memory elements corresponding to the light-emitting elements to be caused to light up among the plurality of light-emitting elements, to any one of a memory state and a non-memory state, in the light-emitting chips in which the selection is enabled by the enable signal;
• and
• transmitting light-up signals for lighting up to light-emitting elements corresponding to memory elements in the memory state, for the plurality of light-emitting chips.

A print head comprising:

• an exposure unit that exposes an image carrier to form an electrostatic latent image;
• and
• an optical unit that focuses light emitted by the exposure unit on the image carrier,
• the exposure unit including:
• a plurality of light-emitting chips that each include a plurality of light-emitting elements and a plurality of memory elements provided respectively corresponding to the plurality of light-emitting elements, each of the memory elements memorizing a corresponding light-emitting element to be caused to light up, each of the plurality of light-emitting chips being capable of lighting up the light-emitting elements more than one, in parallel;
• an enable signal supply unit that transmits an enable signal in common to light-emitting chips belonging to each of M groups into which the plurality of light-emitting chips are divided, where M is an integer more than one, the enable signal enabling selection of light-emitting elements to be caused to light up among the plurality of light-emitting elements;
• a write signal supply unit that transmits a write signal in common to light-emitting chips belonging to each of N classes into which the plurality of light-emitting chips are divided, where N is an integer more than one, the write signal setting memory elements corresponding to the light-emitting elements to be caused to light up among the plurality of light-emitting elements, to any one of a memory state and a non-memory state, in the light-emitting chips in which the selection is enabled by the enable signal;
• and
• a light-up signal supply unit that transmits light-up signals for lighting up to light-emitting elements corresponding to memory elements in the memory state, for the plurality of light-emitting chips.

An image forming apparatus comprising:

• a charging unit that charges an image carrier;
• an exposure unit that exposes the image carrier to form an electrostatic latent image;
• an optical unit that focuses light emitted by the exposure unit on the image carrier;
• a developing unit that develops the electrostatic latent image formed on the image carrier;
• and
• a transfer unit that transfers an image developed on the image carrier to a transferred body,
• the exposure unit including:
• a plurality of light-emitting chips that each include a plurality of light-emitting elements and a plurality of memory elements provided respectively corresponding to the plurality of light-emitting elements, each of the memory elements memorizing a corresponding light-emitting element to be caused to light up, each of the plurality of light-emitting chips being capable of lighting up the light-emitting elements more than one, in parallel;
• an enable signal supply unit that transmits an enable signal in common to light-emitting chips belonging to each of M groups into which the plurality of light-emitting chips are divided, where M is an integer more than one, the enable signal enabling selection of light-emitting elements to be caused to light up among the plurality of light-emitting elements;
• a write signal supply unit that transmits a write signal in common to light-emitting chips belonging to each of N classes into which the plurality of light-emitting chips are divided, where N is an integer more than one, the write signal setting memory elements corresponding to the light-emitting elements to be caused to light up among the plurality of light-emitting elements, to any one of a memory state and a non-memory state, in the light-emitting chips in which the selection is enabled by the enable signal;
• and
• a light-up signal supply unit that transmits light-up signals for lighting up to light-emitting elements corresponding to memory elements in the memory state, for the plurality of light-emitting chips.