Patent ID: 8582172

Claim:
An image scanning apparatus comprising: a light source comprising at least one light emitting diode (LED) to irradiate light to a document which is a scan target; a light source control unit to control a lighting-up point of time of the light source in such a way that an intensity of light irradiated to any one of a plurality of lines of the document from the light source is equal to, or has a difference of less than a predetermined threshold value from, an intensity of light irradiated to another line of the plurality of lines; an image sensor to transform an image formed by light reflected from the document into an electric signal according to a result of controlling the lighting-up point of time; an image sensor control unit arranged to generate a first signal with a first period, which is used to control an exposure time during which the image sensor receives the reflected light, the first period indicating a time required for scanning any one of the plurality of lines in the document; and an output unit to output image data corresponding to the transformed electric signal, wherein the plurality of lines are arranged in a sub scan direction and the light irradiated to each of the plurality of lines has a same color, wherein the light source control unit generates a second signal with a second period, which is used to control lighting-up and extinguishing points of time of the light source, and the first period is significantly larger than the second period in order that the difference is equal to or less than the predetermined threshold value even when the first signal and the second signal are not synchronized with each other.