Exposure apparatus, method for correcting emission quantity of exposure apparatus, and image forming apparatus

An image forming apparatus for making prints according to image data, comprising:

• a photoconductor drum that is charged;
• a plurality of light emitting elements which emit light for exposing the photoconductor drum according to the image data;
• a light quantity measuring circuit which measures a plurality of emission quantities each of which is based on emission intensity and emission time of one of the plurality of light emitting element;
• a difference acquisition circuit which acquires a plurality of first difference and a second difference, wherein the difference acquisition circuit set a reference light quantity based on the plurality of emission quantities when the plurality of light emitting elements are supplied with an original gradation signal having specific values corresponding to the image data and emit light for a predetermined emission time, each of the plurality of first differences is a difference between the reference light quantity and each emission quantity, and the second difference is a difference between a target reference light quantity set corresponding to the image data and the reference light quantity;
• a gradation signal correction circuit generating a plurality of corrected gradation signals by correcting the original gradation signal based on the plurality of first differences so that the emission quantity of the plurality of light emitting elements in the emission time become close to the reference light quantity;
• and
• an emission time correction circuit correcting the emission time based on the second difference so that the plurality of emission quantities of the plurality of light emitting elements corresponding to the plurality of corrected gradation signals become close to the target reference light quantity.

A method for correcting the emission quantity of an exposure apparatus comprising a plurality of light emitting elements and irradiating a photoconductor drum with light for exposure, comprising the following steps:

• measuring a plurality of emission quantities each of which is based on emission intensity and emission time of one of the plurality of light emitting elements when an original gradation signal having specific values corresponding to image data is applied to each of the plurality of light emitting elements;
• setting a reference light quantity based on the plurality of measured emission quantities;
• acquiring a plurality of first differences each of which is a difference between the set reference light quantity and each emission quantity;
• generating a plurality of corrected gradation signals by correcting the original gradation signal based on the plurality of first differences so that the plurality of emission quantities of the plurality of light emitting elements in the emission time become close to the reference light quantity;
• and
• setting a target reference light quantity corresponding to the image data and acquiring a second difference that is the difference between the target reference light quantity and the reference light quantity;
• and
• correcting the emission time based on the second difference so that the plurality of emission quantities of the plurality of light emitting elements corresponding to the plurality of corrected gradation signals become close to the target reference light quantity.