US 8,805,259 B2Granted

Fixing device and image forming apparatus

AssigneeKonica Minolta, Inc.

InventorsTakashi Fujiwara, Shoichi Yoshikawa, Tadayasu Sekioka, Noboru Oomoto, Yoshiyuki Toso, Naoki Miyagawa

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Abstract

A fixing device includes a heating rotating body driven by a motor, a pressing member, a biasing unit, a switching unit that receives rotational power of the motor in order to either separate the pressing member and the heating rotating body or to allow the biasing unit to press the pressing member and the heating rotating body together, a power transmission mechanism that transmits the rotational power of the motor to the switching unit over a first path or a second path, the first path having a larger reduction ratio, and a power transmission targeting unit that switches the target of transmission of rotational power of the motor between the heating rotating body and the switching unit depending on the rotational direction of the motor and that includes a path selection unit that selects the first path during separation and the second path during pressing by the switching unit.

Claims6

Dependent claims

A fixing device comprising:

a heating rotating body driven by a motor;
a pressing member;
a biasing unit configured to place the pressing member and the heating rotating body in a first state by pressing the pressing member and the heating rotating body together with a biasing force so as to form a nip through which a recording sheet with a toner image formed thereon passes;
a switching unit configured to receive rotational power of the motor in order to switch the pressing member and the heating rotating body from the first state to a second state, in which the pressing member and the heating rotating body are not in contact, by separating the pressing member and the heating rotating body from each other in resistance to the biasing force of the biasing unit, and to switch the pressing member and the heating rotating body from the second state to the first state by allowing the biasing force of the biasing unit to press the pressing member and the heating rotating body together;
a power transmission mechanism configured to transmit the rotational power of the motor to the switching unit;
and
a power transmission targeting unit configured to switch a target of the transmission of the rotational power of the motor between the heating rotating body and the switching unit in accordance with whether the motor rotates in a normal direction or a reverse direction, wherein
the power transmission mechanism uses one of a first transmission path and a second transmission path for the transmission of rotational power, a reduction ratio of the first transmission path being larger than a reduction ratio of the second transmission path, and
the power transmission targeting unit includes a path selection unit configured to select the first transmission path when the switching unit switches the pressing member and the heating rotating body from the first state to the second state and to select the second transmission path when the switching unit switches the pressing member and the heating rotating body from the second state to the first state.

6 more elements

An image forming apparatus that forms an image on a recording sheet by electrophotography and includes a fixing device that fixes a toner image to a recording sheet on which the toner image is formed, the fixing device comprising:

a heating rotating body driven by a motor;
a pressing member;
a biasing unit configured to place the pressing member and the heating rotating body in a first state by pressing the pressing member and the heating rotating body together with a biasing force so as to form a nip through which a recording sheet with a toner image formed thereon passes;
a switching unit configured to receive rotational power of the motor in order to switch the pressing member and the heating rotating body from the first state to a second state, in which the pressing member and the heating rotating body are not in contact, by separating the pressing member and the heating rotating body from each other in resistance to the biasing force of the biasing unit, and to switch the pressing member and the heating rotating body from the second state to the first state by allowing the biasing force of the biasing unit to press the pressing member and the heating rotating body together;
a power transmission mechanism configured to transmit the rotational power of the motor to the switching unit;
and
a power transmission targeting unit configured to switch a target of the transmission of the rotational power of the motor between the heating rotating body and the switching unit in accordance with whether the motor rotates in a normal direction or a reverse direction, wherein
the power transmission mechanism uses one of a first transmission path and a second transmission path for the transmission of rotational power, a reduction ratio of the first transmission path being larger than a reduction ratio of the second transmission path, and
the power transmission targeting unit includes a path selection unit configured to select the first transmission path when the switching unit switches the pressing member and the heating rotating body from the first state to the second state and to select the second transmission path when the switching unit switches the pressing member and the heating rotating body from the second state to the first state.

6 more elements

Dependencies are inferred from the claim text.