Patent ID: 6927881

Claim:
An image reader comprising: a light source for radiating light onto an original; an image pickup device into which light reflected from the original or passed through the original enters and which outputs an electric signal corresponding to an amount of the entered light; an image data preparation unit in which the electric signal output from the image pickup device enters and which outputs the electric signal as digital image data; a clock generator for supplying, to the image pickup device, a clock signal for defining a timing at which the electric signal is to be output from the image pickup device; a controller capable of putting the image reader in a reading state for performing an original reading operation, a stand-by state in which the image reader is in a stand-by condition while remaining able to read an original, a power saving state in which supply of power to the light source and the image pickup device is halted, and a warm-up state in which the supply of power to the light source and image pickup device is started, wherein when the image reader is in the power saving state, the controller shifts the image reader from the power saving state to the reading state through the warm-up state and the stand-by state upon receipt of an image read signal; and a clock signal controller for halting supply of the clock signal from the clock generator to the image pickup device when the image reader is in the stand-by state or the power saving state.