Light-emitting chip, light-emitting device, print head and image forming apparatus

A light-emitting chip comprising:

• a substrate;
• a plurality of light-emitting elements arrayed in line on the substrate, each of the light-emitting elements including a light-emitting region having a length in an array direction of the array different from a length in a direction orthogonal to the array direction;
• and
• a light-up current supplying interconnection including a plurality of connecting portions, each of the connecting portions extending on the light-emitting region of a corresponding one of the light-emitting elements in such a direction either the array direction or the direction orthogonal to the array direction that an area of the light-emitting region whose light is blocked is smaller, each of the connecting portions being connected to an electrode provided on the light-emitting region, the light-up current supplying interconnection supplying a current for lighting up to the plurality of light-emitting elements through the plurality of connecting portions, wherein
• each of the plurality of light-emitting elements is isolated by a trench with a mesa structure, a longer direction of the light-emitting region being orthogonal to a shorter direction of the light-emitting region, the mesa structure including a forward mesa step extending in the longer direction of the light emitting region and the mesa structure including a reverse mesa step extending in the shorter direction of the light emitting region, and
• the light-up current supplying interconnection is arranged adjacent to the light-emitting region of each of the light-emitting elements, and has a reflecting surface reflecting light emitted with a spread so that the light is narrowed toward a direction perpendicular to the light-emitting region and in a direction away from the light-emitting elements.

A light-emitting device comprising:

• a plurality of light-emitting chips each including:
• a substrate;
• a plurality of light-emitting elements arrayed in line on the substrate, each of the light-emitting elements including a light-emitting region having a length in an array direction of the array different from a length in a direction orthogonal to the array direction;
• a plurality of transfer elements provided on the substrate so as to correspond to the respective light-emitting elements, each of the transfer elements designating a corresponding light-emitting element as a control target for lighting up or not lighting up by changing to an ON state;
• and
• a light-up current supplying interconnection including a plurality of connecting portions, each of the connecting portions being provided on the light-emitting region of a corresponding one of the light-emitting elements in a shorter direction of the light-emitting region either the array direction or the direction orthogonal to the array direction, each of the connecting portions being connected to an electrode provided on the light-emitting region, the light-up current supplying interconnection supplying a current for lighting up to the plurality of light-emitting elements through the plurality of connecting portions,
• each of the plurality of light-emitting elements is isolated by a trench with a mesa structure, a longer direction of the light-emitting region being orthogonal to a shorter direction of the light-emitting region, the mesa structure including a forward mesa step extending in the longer direction of the light emitting region and the mesa structure including a reverse mesa step extending in the shorter direction of the light emitting region, and
• the light-up current supplying interconnection is arranged adjacent to the light-emitting region of each of the light-emitting elements, and has a reflecting surface reflecting light emitted with a spread so that the light is narrowed toward a direction perpendicular to the light-emitting region and in a direction away from the light-emitting elements, and
• the light-emitting device further comprising:
• a transfer signal supplying unit transmitting transfer signals to the plurality of light-emitting chips for driving each of the transfer elements of the light-emitting chips so that the ON state sequentially propagates;
• and
• a light-up current supplying unit supplying a current for lighting up to the plurality of light-emitting chips.

A print head comprising:

• a light-emitting unit;
• and
• an optical unit causing light emitted by the light-emitting unit to form an image,
• the light-emitting unit including a plurality of light-emitting chips each including:
• a substrate;
• a plurality of light-emitting elements arrayed in line on the substrate, each of the light-emitting elements including a light-emitting region having a length in an array direction of the array different from a length in a direction orthogonal to the array direction;
• a plurality of transfer elements provided on the substrate so as to correspond to the respective light-emitting elements, each of the transfer elements designating a corresponding light-emitting element as a control target for lighting up or not lighting up by changing to an ON state;
• each of the plurality of light-emitting elements is isolated by a trench with a mesa structure, a longer direction of the light-emitting region being orthogonal to a shorter direction of the light-emitting region, the mesa structure including a forward mesa step extending in the longer direction of the light emitting region and the mesa structure including a reverse mesa step extending in the shorter direction of the light emitting region, and
• a light-up current supplying interconnection including a plurality of connecting portions, each of the connecting portions being provided on the light-emitting region of a corresponding one of the light-emitting elements in a shorter direction of the light-emitting region either the array direction or the direction orthogonal to the array direction, each of the connecting portions being connected to an electrode provided on the light-emitting region, the light-up current supplying interconnection supplying a current for lighting up to the plurality of light-emitting elements through the plurality of connecting portions,
• the light-up current supplying interconnection is arranged adjacent to the light-emitting region of each of the light-emitting elements, and has a reflecting surface reflecting light emitted with a spread so that the light is narrowed toward a direction perpendicular to the light-emitting region and in a direction away from the light-emitting elements, and
• the light-emitting unit further including:
• a transfer signal supplying unit transmitting transfer signals to the plurality of light-emitting chips for driving each of the transfer elements of the light-emitting chips so that the ON state sequentially propagates;
• and
• a light-up current supplying unit supplying a current for lighting up to the plurality of light-emitting chips.

An image forming apparatus comprising:

• an image carrier;
• a charging unit charging the image carrier;
• an exposure unit exposing the image carrier through an optical unit;
• a developing unit developing an electrostatic latent image exposed by the exposure unit and formed on the image carrier;
• and
• a transfer unit transferring an image developed on the image carrier to a transferred body,
• the exposure unit including a plurality of light-emitting chips each including:
• a substrate;
• a plurality of light-emitting elements arrayed in line on the substrate, each of the light-emitting elements including a light-emitting region having a length in an array direction of the array different from a length in a direction orthogonal to the array direction;
• a plurality of transfer elements provided on the substrate so as to correspond to the respective light-emitting elements, each of the transfer elements designating a corresponding light-emitting element as a control target for lighting up or not lighting up by changing to an ON state;
• each of the plurality of light-emitting elements is isolated by a trench with a mesa structure, a longer direction of the light-emitting region being orthogonal to a shorter direction of the light-emitting region, the mesa structure including a forward mesa step extending in the longer direction of the light emitting region and the mesa structure including a reverse mesa step extending in the shorter direction of the light emitting region, and
• a light-up current supplying interconnection including a plurality of connecting portions, each of the connecting portions being provided on the light-emitting region of a corresponding one of the light-emitting elements in a shorter direction of the light-emitting region either the array direction or the direction orthogonal to the array direction, each of the connecting portions being connected to an electrode provided on the light-emitting region, the light-up current supplying interconnection supplying a current for lighting up to the plurality of light-emitting elements through the plurality of connecting portions,
• the light-up current supplying interconnection is arranged adjacent to the light-emitting region of each of the light-emitting elements, and has a reflecting surface reflecting light emitted with a spread so that the light is narrowed toward a direction perpendicular to the light-emitting region and in a direction away from the light-emitting elements, and
• the exposure unit further including:
• a transfer signal supplying unit transmitting transfer signals to the plurality of light-emitting chips for driving each of the transfer elements of the light-emitting chips so that the ON state sequentially propagates;
• and
• a light-up current supplying unit supplying a current for lighting up to the plurality of light-emitting chips.