Patent ID: 8149468

Claim:
An image reading device comprising: a reading unit; and a controller connected to the reading unit through a transmission path, wherein the controller includes: a first clock generator which generates a first reference clock; a second clock generator which generates a second reference clock; a line synchronizer which generates a line synchronization signal based on the first reference clock; a clock transmitter which transmits the line synchronization signal and a unit clock based on the first reference clock to the reading unit; and a processor which execute a process based on the second reference clock and which is synchronized with the line synchronization signal, and wherein the reading unit includes: a reading sensor which reads a document line by line based on the unit clock and the line synchronization signal, a data transmitter which transmits, to the controller, reading data obtained by quantizing a read image signal output from the reading sensor based on the unit clock, and a timing generator which generates, based on the unit clock, a driving timing signal used for driving the reading sensor and a transmission timing signal used for controlling the transmission timing of the reading data from the data transmitter.