Image forming apparatus, and method of controlling warming-up time of image forming apparatus

An image forming apparatus comprising:

• a fixing unit comprising a fixing member and a pressing member pressed against the fixing member to fix a toner image on a recording medium passed between the fixing member and the pressing member by applying heat and pressure to the toner image on the recording medium using the fixing member and the pressing member in a fixing process;
• and
• a fixing process managing system that controls heating of the fixing member by selectively switching between a time mode and a temperature mode,
• the fixing unit being ready for a fixing process when a given time elapses after activation of the image forming apparatus in the time mode,
• the fixing unit being ready for a fixing process when a temperature of the fixing member attains a given reference temperature after activation of the image forming apparatus in the temperature mode,
• the fixing process managing system comprising a mode switchover unit configured to select one of the temperature mode and the time mode for the fixing unit,
• the fixing process managing system selecting the temperature mode instead of the time mode when a supply amount of electrical power to be supplied to the fixing unit when activating the image forming apparatus falls below a required level of electrical power supply.