Patent ID: 8200113
Filing Date: 2012-06-12
Classification: G03G

Abstract:
1. A fixing apparatus comprising: a first heating element and a second heating element configured to generate heat by electric power supplied from a power supply; a rotating member configured to rotate to fix an image formed on a printing medium by the heat of the first and second heating elements provided within the rotating member; a pressing member configured to rotate in contact with the rotating member to press the printing medium to the rotating member; a first triac configured to switch a power supply from the power supply to the first heating element between an ON state and an OFF state; a second triac configured to switch a power supply from the power supply to the second heating element between the ON state and the OFF state; a first driving circuit configured to drive the first triac; a second driving circuit configured to drive the second triac; a temperature detecting element configured to be assigned in a vicinity of the first and second heating elements, and to detect a temperature; a control unit configured to control the first and second driving circuits in accordance with the temperature detected by the temperature detecting element; a safety element configured to be connected in series with the power supply, and to de-energize the first and second heating elements upon detecting an abnormal temperature rise of the first and second heating elements; a rotation detection circuit configured to detect a rotation state of one of the rotating member and the pressing member; and a limiting circuit configured to limit driving of the second driving circuit in accordance with an output from the rotation detection circuit, wherein, in response to the rotation detection circuit detecting that one of the rotating member and the pressing member is not rotating, (i) the first driving circuit is controlled by the control unit, regardless of the rotation state of one of the rotating member and the pressing member, and (ii) the driving of the second driving circuit is limited by the limiting circuit in accordance with the output from the rotation detection circuit to suppress energization of the second heating element, regardless of a control by the control unit.