| 摘要 |
PROBLEM TO BE SOLVED: To highly accurately correct light distribution by correcting a displacement caused in a document reading position.SOLUTION: Light is emitted to a shading plate that is provided in a position different from a document reading position, while an illumination unit 101 is displaced. On the basis of the luminance value of the reflected light, a shading correction is made. Light is emitted to a reading position used before a document is fed to the reading position, while the illumination unit is displaced in the same direction used in the shading correction. By comparing the luminance value of the reflected light at the time and a luminance value after the shading correction are compared, luminance value reference data before the document is read is created. After the document is read, light is again emitted to the reading position, in which the document is not present, while the illumination unit is displaced in the same direction as the direction used for the shading correction. The luminance value of the reflected light at this time and the reference data of the luminance value are compared. If a quantity of light changes beyond a predetermined quantity, a pressure plate motor or a document conveyance motor control circuit 302 is controlled and the reading position is relatively displaced. |
