Patent ID: 7345796

Claim:
An image scanner comprising: a photoelectric conversion element which has a light-receiving face and outputs an electrical signal corresponding to a contrast of light emitted to the light-receiving face; an optical unit including a light source, a lens, and a plurality of mirrors which guide the light reflected from an object to which the light from the light source is emitted and thereby which is illuminated, the lens imaging the reflected light on the light-receiving face of the photoelectric conversion element; a photoelectric conversion element driving circuit which drives the photoelectric conversion element and fetches the electrical signal at a predetermined timing; a lens moving mechanism which moves the lens in an optical-axis direction by a predetermined distance; and a focus control circuit which generates a focus signal capable of setting an optimum position of the lens in accordance with the electrical signal output from the photoelectric conversion element and which outputs a lens moving signal showing a distance for the lens moving mechanism to move the lens in accordance with the focus signal, wherein the focus control circuit detects that a distance between the light-receiving face of the photoelectric conversion element and the object is different from a reference value and generates the lens moving signal for moving the lens a predetermined distance by a predetermined distance.