Patent ID: 8400659
Filing Date: 2013-03-19
Classification: G03G

Abstract:
1. An image forming apparatus, comprising: a control unit configured to control operations of the image forming apparatus; an engine unit configured to perform image formation under control of the control unit; a universal transmission line that connects the control unit and the engine unit so that communication between the control unit and the engine unit can be established and data can be transferred between the control unit and the engine unit; and a dedicated transmission line that connects the control unit and the engine unit so that data can be transferred between the control unit and the engine unit even when communication has not been established between the control unit and the engine unit, wherein when the image forming apparatus is powered, the control unit sends a mode signal to the engine unit via the dedicated transmission line, wherein the mode signal is a signal indicative of whether a power mode is to be set to a normal mode where power is supplied to every component of the image forming apparatus, upon receiving the mode signal from the control unit via the dedicated transmission line, if the mode signal indicates that the power mode is to be set to the normal mode, the engine unit activates predetermined components in the image forming apparatus, after activation of the predetermined components, the control unit and the engine unit establish communication via the universal transmission line, after establishment of the communication, if the mode signal indicates that the power mode is to be set to a mode other than the normal mode, the control unit sends a setting command to the engine unit via the universal transmission line to set the power mode to a power-saving mode that is specified in the setting command from among a plurality of power-saving modes where power is supplied to only some components of the image forming apparatus, upon receiving the setting command from the control unit via the universal transmission line, the engine unit activates a part of the image forming apparatus so that the image forming apparatus switches to the power-saving mode that is specified by the setting command, the engine unit sends a state signal indicative of a state of the engine unit to the control unit via the dedicated transmission line, and upon receiving the state signal via the dedicated transmission line, if the state signal indicates that the engine unit is in a ready state for a process for establishing communication between the control unit and the engine unit, the control unit establishes communication with the engine unit via the universal transmission line.