FIXING APPARATUS

• US 20080267643A1
• Filed: 04/24/2008
• Published: 10/30/2008
• Est. Priority Date: 04/27/2007
• Status: Active Grant

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Takami, Hiroshi
• Granted Patent: US 8,200,113 B2
• Time in Patent Office: Days
• US Class Current: 399/33
• CPC Class Codes: G03G 15/2039 with means for controlling the fixing temperature
• CPC Class Codes: G03G 15/5004 Power supply control, e.g. power-saving mode, automatic power turn-off
• CPC Class Codes: G03G 2215/2035 the fixing nip having a stationary belt support member opposing a pressure member

Abstract

A fixing apparatus including a rotation detection circuit which detects the rotation state of the rotating member or pressing member, and one to (N−1) limiting circuits which limit driving of one to (N−1) driving circuits in accordance with an output from the rotation detection circuit, wherein when the rotation detection circuit detects that the rotating member or pressing member is not rotating, the one to (N−1) limiting circuits limit driving of the one to (N−1) driving circuits in accordance with the output from the rotation detection circuit to suppress energization of the heating elements regardless of the driving signals from the control unit to the driving circuits.

Claims

1. A fixing apparatus comprising:

N heating elements, where N is an integer and N≧

2, each of which generates heat in accordance with power supplied from a power supply;

a rotating member which heats an image borne by a recording medium by the heat of the heating elements;

a pressing member which contacts the rotating member;

N driving circuits each of which switches a power supply line from the power supply to the heating elements between an ON state and an OFF state;

a control unit which controls the driving circuits to make the heating elements maintain a set temperature by outputting driving signals to the driving circuits;

a safety element which is connected in series with the power supply line that connects the heating elements to the power supply and de-energizes the heating elements upon detecting an abnormal temperature rise of the heating elements;

a rotation detection circuit which detects a rotation state of one of the rotating member and the pressing member; and

one to (N−

1) limiting circuits which limit driving of the one to (N−

1) driving circuits in accordance with an output from the rotation detection circuit,

wherein when the rotation detection circuit detects that one of the rotating member and the pressing member is not rotating, the one to (N−

1) limiting circuits limit driving of the one to (N−

1) driving circuits in accordance with the output from the rotation detection circuit to suppress energization of the heating elements regardless of the driving signals from the control unit to the driving circuits.

2. The apparatus according to claim 1, wherein each of the one to (N−

1) limiting circuits has a switching element which switches the driving circuit between the ON state and the OFF state in accordance with the output from the rotation detection circuit, and when the rotation detection circuit detects that one of the rotating member and the pressing member is not rotating, the one to (N−

1) switching elements set the driving circuit in the OFF state.

3. A fixing apparatus comprising:

a heating element which generates heat in accordance with power supplied from a power supply;

a rotating member which heats an image borne by a recording medium by the heat of the heating element;

a pressing member which contacts the rotating member;

a driving circuit which switches a power supply line from the power supply to the heating element between an ON state and an OFF state;

a control unit which controls the driving circuit to make the heating element maintain a set temperature by outputting a driving signal to the driving circuit;

a safety element which is connected in series with the power supply line that connects the heating element to the power supply and de-energizes the heating element upon detecting an abnormal temperature rise of the heating element;

a rotation detection circuit which detects a rotation state of one of the rotating member and the pressing member; and

a limiting circuit which limits driving of the driving circuit in accordance with an output from the rotation detection circuit,

wherein when the rotation detection circuit detects that one of the rotating member and the pressing member is not rotating, the limiting circuit limits driving of the driving circuit in accordance with the output from the rotation detection circuit to suppress energization of the heating element regardless of the driving signal from the control unit to the driving circuit.

4. The apparatus according to claim 3, wherein the limiting circuit has a switching element which periodically switches the driving circuit between the ON state and the OFF state in accordance with the output from the rotation detection circuit, and when the rotation detection circuit detects that one of the rotating member and the pressing member is not rotating, the switching element periodically sets the driving circuit in the OFF state.