| 摘要 |
PROBLEM TO BE SOLVED: To provide an image reader that can read an image with excellent image quality at all times and utilize a light source up to the limit of its length. SOLUTION: An LED is driven by a constant current I (202), and a line CCD reads a light emitted from the LED photoelectrically to detect a density value D (204). Then the detected density value D is compared with a default to discriminate whether or not the density value D is in excess of the default by a prescribed value (206), and a drive current increaseαis calculated depending on the difference between the density value D and the default (208). Whether or not the increased drive current Iαexceeds a prescribed value is discriminated (210, 212), and when the increased drive current Iαexceeds the prescribed value, a message or the like denoting the necessity of replacement of the LED is displayed on a monitor (214).
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