Patent ID: 7542691

Claim:
An image forming apparatus comprising: a first sub power source including a capacitor; a second sub power source including a secondary battery; a first fixing heater for heating a fixing section to fix toner onto a recording sheet by an electric power supplied from the first sub power source; a second fixing heater for heating the fixing section by an electric power supplied from the second sub power source; a third fixing heater for heating the fixing section by an electric power supplied from an external power source serving as a main power source; a first charging switch for switching over charging and charge-suspending of the first sub power source; a second charging switch for switching over charging and charge-suspending of the second sub power source; a third charging switch for switching over charging and charge-suspending of the first sub power source; a first charging/discharging switch for switching over discharging of the first sub power source to drive the first fixing heater, and charging of the first sub power source; a second charging/discharging switch for switching over discharging of the second sub power source to drive the second fixing heater, and charging of the second sub power source; a third heater driving switch for switching over driving of the third fixing heater by the electric power supplied from the external power source, and drive-suspending of the third fixing heater; an apparatus condition judger for judging whether the image forming apparatus is in a first condition where a rapid temperature rise is required to rapidly raise a temperature of the fixing section to a predetermined first temperature zone, or in a second condition where the temperature of the fixing section is required to be maintained in the first temperature zone; and a controller for controllably switching the first charging/discharging switch to the discharging, the second charging/discharging switch to the charging, the second charging switch to the charge-suspending, and the third heater driving switch to the driving when the apparatus condition judger judges that the apparatus is in the first condition, for controllably switching the first charging/discharging switch to the charging, the first charging switch to the charge-suspending, the second charging/discharging switch to the discharging, and the third heater driving switch to the driving when the apparatus condition judger judges that the apparatus is in the second condition, and controllably switches the third charging switch to the charge-suspending of the first sub power source by the power supply from the second sub power source when it is judged that the main electric power is supplied to the image forming apparatus, and controllably switches the third charging switch to the charging of the first sub power source by the power supply from the second sub power source when it is judged that the main power supply to the image forming apparatus is cut off.