Patent ID: 7224500

Claim:
An image reader for reading an image recorded on an original, comprising: a light source for emitting a light toward said original; an imaging device for receiving the light emitted from said light source and having passed through said original; and light-amount regulating means for regulating a light amount of said light source, said light-amount regulating means setting an electric-current value of said light source so as to make an output value of said imaging device converge within a predetermined range, wherein said electric-current value of said light source is used when reading said image, and wherein said light-amount regulating means is further configured to: store at least one electric-current set value of said light source and the predetermined range; calculate a central value from said at least one electric-current set value; compare the predetermined range with a first output value of said image device which is obtained using said central value; use said central value when reading said image if the first output value converges the predetermined range; and continue to calculate another central value from said at least one electric-current set value until another output value of said image device obtained using the other central value converges the predetermined range if the first output value does not converge the predetermined range, and use the other central value when reading said image, if the other output value converges the predetermined range.