US Patent 7492479 Image forming apparatus and image forming method

In an initializing process at a time of switch-on, a scanner CPU sends an initialization command request to a system CPU. Upon receiving the initialization command request from the scanner CPU, the system CPU sends an initialization command to the scanner CPU. The scanner CPU, which has received the initialization command, executes an initializing process. When the initialization is completed, the scanner CPU informs the system CPU of the completion of initialization. After the system CPU is informed of the completion of initialization from all sub-control units (including a printer CPU and a panel CPU in the embodiment), the system CPU instructs an LCD to display “Ready” and enters a standby state.