Patent ID: 8422087

Claim:
An image reading method of a carriage traveling type for receiving reflected light of light applied to an original document surface from a line light source mounted on a carriage traveling in a sub-scanning direction of original document reading to obtain image data, comprising the steps of: (a) driving the carriage using a motor clock signal with a beforehand set longest period in starting reading the document; (b) lighting the line light source for a predetermined time at timing synchronized with the motor clock signal; (c) capturing image data stored during the step (b) from the line sensor for a reading period subsequent to the reading period in the step (b) of the line light source; (d) driving the stepping motor using a motor clock signal with a period shorter than that of the motor clock signal of the step (a) by a predetermined time; (e) executing the steps (b) and (c); (f) repeating the steps (d) and (e) until the period of the motor clock signal becomes a period in constant-velocity traveling of the carriage; and (g) driving the stepping motor using the motor clock signal with the period of constant-velocity traveling, and after lighting the line light source for a predetermined time at timing synchronized with the motor clock signal, capturing image stored during a lighted reading period from the line sensor for a reading period subsequent to the lighted reading period during which the line light source is lit.