Patent ID: 7034858
Filing Date: 2006-04-25
Classification: G06K,H04N

Abstract:
1. An LED array exposure device comprising: a plurality of light-emitting elements for exposing a photoconductor so as to form an image, the plurality including a light-emitting element for which correction is performed, the light-emitting element, so as to be compensated for variations, driven by a driving current obtained from a standard driving current common to the light-emitting elements through a process of incorporating a light quantity correction coefficient for compensating for variations of light quantity emitted from the light-emitting element, and a beam spot area correction coefficient for compensating for variations of a beam spot area formed on the photoconductor, the light-emitting element being so controlled as to be driven by the driving current for a length of time in accordance with a gray level of an image pixel to which the light-emitting element corresponds, wherein an average value is obtained by averaging out beam spot areas of the plurality of light-emitting elements, including the light-emitting element; a difference is obtained by subtracting a beam spot area of the light-emitting element from the average value of the beam spot areas; a ratio of the difference is obtained by dividing the difference by the average value of the beam spot areas; a beam spot area correction coefficient for the light-emitting element is calculated in accordance with the ratio of the difference; a granularity correction coefficient for reducing granularity is calculated in accordance with the magnitude of a parameter that affects granularity in an image; and the driving current for the light-emitting element is obtained by multiplying the standard driving current by the light quantity correction coefficient, the beam spot area correction coefficient, and the granularity correction coefficient.