Patent ID: 8259366

Claim:
An image reading apparatus configured to read an image of a document by causing a scanning drive unit to perform scanning drive of a reading unit, the image reading apparatus comprising: a drive source; a speed change mechanism provided in a transmission unit that transmits a driving force from the drive source to the scanning drive unit and configured to change a transmission ratio of the transmission unit by selectively bringing one of first and second couplings into a connected state; a selector configured to selectively press one of the first and second couplings to bring one of the couplings into the connected state; a detector configured to detect the connected state of the second coupling, the detector outputting different signals between when the second coupling is in a connected state in which the driving force is able to be transmitted and when the second coupling is in a non-connected state in which the driving force is not able to be transmitted; and a controller configured to control a scanning position of the reading unit by applying a drive control signal to the drive source, wherein the controller controls the scanning position of the reading unit, after the selector changes a selection to be pressed from the first coupling to the second coupling and until the detector detects the connected state of the second coupling, by inhibiting the scanning drive unit from performing scanning when the connected state of the first coupling is removed, or by driving the scanning drive unit via the first transmission portion when the connected state of the first coupling remains, and after the detector detects the connected state of the second coupling after the selector changes a selection to be pressed from the first coupling to the second coupling by driving the scanning drive unit via the second transmission portion.