JPH1124434A - Driving attachable and detachable mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute jam processing only by operating a rotational force imparting means without resisting the load of a transmission mechanism on a driving side by releasing a coupling state between a driving part and the driven part of a transfer material carrying roller by automatically moving a holding means when an opening and closing cover is opened. SOLUTION: When an opening and closing cover 7 is opened in order to remove a transfer material from a gap between a fixing roller 1 and a pressure roller in the case that a jam occurs, the pressing force of a projection 7a with respect to an operation knob 5 is released and a rotary shaft 9 is forcibly moved in the shaft direction (opposite direction to an arrow A) by the energizing force of an elastic member 8. As the result, a gear part 5a and a second driven gear 6 are meshed and a meshed state between a relay gear 3 and a driving gear 4 is released. Therefore, when the knob 5 is turned in the prescribed direction in this state, a second driven roller 6 meshed with the gear part 5a is rotated and the roller 1 is rotated together with a rotary shaft 1a. Thus, the transfer materials jammed between the rollers are removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive contact / separation mechanism for a transfer material transport roller in an image forming apparatus such as a copying machine, and more particularly, to a drive unit of a drive source for applying a rotational force to the transfer material transport roller. The present invention relates to a drive contact / separation mechanism for detachably connecting a driven part provided on a rotation shaft of a transfer material conveying roller.

[0002]

2. Description of the Related Art Generally, an image forming apparatus such as a copying machine is provided with a conveying means for conveying a transfer material along a predetermined path in order to perform various processes associated with image formation on a transfer material such as copy paper. I have. Such a transporting unit generally includes a pair of rollers that are opposed to and contact each other, and transports a transfer material that enters a nip portion between the rollers as the rollers rotate.

A fixing device of an image forming apparatus is a device for fixing a toner image to a transfer material, and also has a function as a conveying means for sending the transfer material toward a paper discharge tray. That is, the fixing device has a fixing roller (transfer material conveying roller) having a predetermined heat source built therein and a pressure roller (transfer material conveying roller) pressed against the fixing roller, and enters a nip portion between these rollers. At the same time, the toner image carried on the transfer material is fixed to the transfer material by heat while the transfer material is conveyed by the rotational force. In this case, the fixing roller is rotated by the driven gear provided on the rotation shaft meshing with the driving gear of the driving source.

When a jam (paper jam) occurs in which the transfer material remains between the fixing roller and the pressure roller, the jam detector operates to stop the main motor and stop the rotation of the fixing roller. . Conventionally, an operation knob is provided at the end of the rotation shaft of the fixing roller so that the transfer material can be removed from between the fixing roller and the pressure roller when such a jam occurs. That is, by manually rotating the operation knob, the fixing roller is rotated to remove the transfer material jammed between the rollers.

[0005]

However, since the rotation operation of the operation knob is conventionally performed in a state where a driven gear provided on a rotation shaft of a fixing roller and a driving gear of a driving source are engaged with each other, the driving operation is performed. It must be performed against the load of a driving force transmission system such as various gears or chains that transmit power to the driving gear. Therefore, if a large amount of operation force is involved and the operation knob is forcibly rotated, the chain may be detached from the sprocket provided on the drive gear.

In order to solve such a problem, Japanese Patent Application Laid-Open No. 58-18663 and Japanese Utility Model Application Laid-Open No.
In Japanese Patent Publication No. 573, a driving contact / separation mechanism is provided so as to connect / disconnect a driving gear of a driving source and a driven gear of a fixing roller so that the meshing state between the driven gear and the driving gear can be released. I have to. More specifically, the drive contact / separation mechanism includes a rotating shaft slidable in the axial direction, an operation knob provided at one end of the rotating shaft, and a driven gear provided at the other end of the rotating shaft and serving as a fixing roller. And a relay gear that can mesh with the drive gear of the drive source. When the operator grips the operation knob and moves the rotation shaft to one side in the axial direction, the driving gear of the driving source and the driven gear of the fixing roller mesh with each other via the relay gear, and the rotation shaft is When the gear is moved to the other side in the direction, the meshing state between the driven gear and the drive gear via the relay gear is released, and the driven gear meshes only with the relay gear.

However, in this case, the rotary shaft of the drive contact / separation mechanism is constantly urged by a spring in a direction in which the relay gear meshes with the driven gear and the drive gear.
In order to release the meshing state between the driven gear and the drive gear, the rotating shaft of the drive contact / separation mechanism must be moved in the axial direction by the operation knob against the urging force of the spring. This involves an operation force. Moreover, in order to cope with the jam, it is necessary to perform a two-stage operation of rotating the rotating shaft of the driving contact / separation mechanism in the axial direction and then rotating the rotating shaft with the operation knob, which makes the operation extremely complicated. Become.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a transfer material conveying roller in an image forming apparatus which can cope with a jam with a light operation force and a simple operation. It is another object of the present invention to provide a drive contact / separation mechanism.

[0009]

According to an aspect of the present invention, there is provided a transfer material conveying roller for sending and transferring a transfer material in a predetermined direction, and a rotational force applied to the transfer material transfer roller. A driving unit provided in the image forming apparatus having a driving unit for applying a driving force, and a driven contacting / separating mechanism that detachably connects the driven unit and the driven unit fixed to the rotation shaft of the transfer material conveying roller. A rotating force transmitting unit that is connected to both the unit and the driving unit and transmits the rotating force of the driving unit to the driven unit; and a rotating force applying unit that is connected to the driven unit and applies the rotating force to the driven unit.
Holding the torque transmitting means and the torque applying means, the torque transmitting position at which the torque transmitting means is connected to the driving section and the driven section, and the connection between the torque transmitting means and the driving section is released and the rotation is performed. A holding unit movable between a rotational force input position where the force applying unit is connected to the driven unit, an urging unit for urging the holding unit toward the rotational force input position, and a transfer material conveying roller It is provided on an opening and closing cover that opens and closes parts,
When the opening / closing cover is closed, the holding means is pressed against the urging force of the urging means to move toward the rotational force transmitting position, and when the opening / closing cover is opened, the pressing force against the holding means is reduced. And a pressing means for releasing the holding means to move to the rotational force input position by the urging means.

According to the first aspect of the present invention, simply by opening the opening / closing cover, the holding means is automatically moved, and the connection between the rotational force transmitting means and the driving unit is released, that is, the driving unit and the transfer unit are transferred. Since the connection state of the material conveying roller with the driven portion is released, the jam clearance can be performed only by operating the rotating force applying means without resisting the load of the transmission mechanism on the driving side.

According to a second aspect of the present invention, in the first aspect of the present invention, the drive contact / separation mechanism constitutes one unit detachably attached to a main body of the image forming apparatus together with a transfer material conveying roller. It is characterized by doing.

According to the second aspect of the present invention, the transfer device for transferring the transfer material can be designed to be compact.

According to a third aspect of the present invention, in the second aspect of the present invention, the main body of the image forming apparatus has a release lever for releasing the mounting of the unit, and the pressing means comprises a unit. Abuts on the release lever when the cover is not completely attached to the main body of the image forming apparatus to prevent the opening / closing cover from being closed.

According to the third aspect of the present invention, it is not necessary to separately provide a means for blocking the opening / closing cover on the opening / closing cover, which is advantageous in cost.

According to a fourth aspect of the present invention, in the first aspect, the rotational force applying means is connected to the driven part after the connection between the rotational force transmitting means and the driving part is released. Features.

According to the fourth aspect of the present invention, when the opening / closing cover is opened while the driving section is applying the rotational force to the rotational force transmitting means (during copying, etc.), the rotational force transmitting means is opened. Since the rotational force applying unit is connected to the driven unit after the drive of the transfer material conveyance roller is completely removed from the driving unit,
The rotation force applying means and the driven portion are prevented from being damaged.

According to a fifth aspect of the present invention, in a fixing unit of an image forming apparatus for fixing a toner image to a transfer material,
A rotatable fixing roller containing a predetermined heat source, a first driven gear provided at one end of a rotation shaft of the fixing roller,
The second driven gear provided on the other end of the rotation shaft of the fixing roller meshes with both the driving gear and the first driven gear provided on the apparatus main body of the image forming apparatus, and the driving gear is driven to rotate. A relay gear for transmitting a force to the rotation shaft of the fixing roller via a first driven gear, an operation knob having a gear portion that meshes with the second driven gear, and a relay gear at one end, and a relay gear at the other end. The operation knob is rotatably held, the rotational force transmission position at which the relay gear meshes with the drive gear and the first driven gear, the meshing state between the relay gear and the drive gear is released, and the gear portion of the operation knob is moved to the second position. A rotating shaft portion movable between a rotating force input position meshed with the second driven gear and a biasing means for biasing the rotating shaft portion toward the rotating force input position; Is provided on the opening and closing cover when the opening and closing cover of the image forming apparatus is closed. Pressed by the projections, they are moved toward the rotational force transmitting position against the urging force of the urging means, and when the opening and closing cover is opened, the pressing force by the projections is released and the urging means rotates It is characterized by being moved to a force input position.

According to the fifth aspect of the present invention, simply by opening the opening / closing cover, the rotating shaft portion is automatically moved, and the connection state between the relay gear and the driving gear is released, that is, the driving gear and the fixing roller. Since the connection with the first driven gear is released, the jam clearance can be performed only by turning the operation knob without resisting the load on the drive-side transmission mechanism.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 shows a fixing unit 30 for fixing a toner image to a transfer material, and an apparatus main body 45 of an image forming apparatus in which the fixing unit 30 is detachably set. FIG. 5 shows a state in which the fixing unit 30 is pulled out from the apparatus main body 45 side. In this case, as shown in the drawing, when the release lever 40 provided on the apparatus main body 45 is rotated outward so as to separate from the fixing unit 30, the fixing unit 30 is pulled out from the apparatus main body 45. ing. When the fixing unit 30 is pushed into the apparatus main body 45 and is completely set, the release lever 40 rotates inward so as to approach the side surface of the fixing unit 30.

As shown in FIG. 3, the fixing unit 30 is set at a position on the apparatus main body 45 side where the fixing unit 30 is set.
A motor M is provided as a drive source for applying a rotational force to a fixing roller 1 described later. The driving force of the motor M is transmitted to a driving gear 4 of the fixing unit 30 that meshes with a relay gear 3 described later via a force transmission mechanism 32.

As shown in FIG. 1, the fixing unit 30
A fixing roller 1 having a built-in heat source for performing a fixing process and also serving as a conveying roller for conveying a transfer material;
A pressure roller (not shown) that is pressed against the fixing roller 1, a first driven gear 2 (to be described later) of the fixing roller 1, and an apparatus main body 45.
Drive / separation mechanism 4 that connects the drive gear 4 on the side so as to be able to come and go
7 are provided.

The rotating shaft 1a of the fixing roller 1 is rotatably mounted on both side plates 10 and 11 forming a housing of the fixing unit 30 via bearings 12 and 13, respectively. A first driven gear 2 is fixedly attached to one end of the rotating shaft 1a, and a second driven gear 6 is fixedly attached to the other end of the rotating shaft 1a.
On the other hand, the drive contact / separation mechanism 47 has a rotating shaft 9 rotatably attached to both side plates 10 and 11 via bearings 14 and 15, respectively. The first end of the rotating shaft 9
A relay gear 3 meshing with the driven gear 2 is fixedly mounted, and an operating knob 5 having a gear portion 5a meshable with the second driven gear 6 is provided at the other end of the rotating shaft 9 with a bearing 14. It is rotatably mounted via.

The rotating shaft 9 is mounted so as to be slidable in the axial direction. Specifically, the rotating shaft 9 is configured as shown in FIG.
The fixing unit 30 is connected to the first driven gear 2 as shown in FIG.
When the relay gear 3 is inserted and set into the apparatus main body 45 from the side where is located, the relay gear 3 meshes with the drive gear 4 on the apparatus main body 45 side, and the gear portion 5a of the operation knob 5 is disengaged from the second driven gear 6 in FIG. In which the relay gear 3 is disengaged from the drive gear 4 on the apparatus main body 45 side and the gear portion 5a of the operation knob 5 meshes with the second driven gear 6 so as to slide in the axial direction. It has become.

As shown in FIG. 4, between the operation knob 5 and the side plate 10 or between the bearings 14 and 16,
The urging force is applied to the rotating shaft 9 to move the rotating shaft 9 to the position shown in FIG. 2 where the gear portion 5a and the second driven gear 6 mesh with each other and the meshing state between the relay gear 3 and the driving gear 4 is released. An elastic member 8 such as a coil spring to be moved is inserted.

Further, the fixing unit 3 is attached to the apparatus main body 45.
An opening / closing cover 7 that opens and closes a portion where the 0 is inserted / removed is attached. On the inner surface of the opening / closing cover 7, a projection 7a is provided at a position where it comes into contact with the operation knob 5 of the fixing unit 30. When the opening / closing cover 7 is closed in a state where the fixing unit 30 is set on the apparatus main body 45 as shown in FIG. 1, the projection 7a comes into contact with the operation knob 5 to push the rotating shaft 9 against the urging force of the elastic member 8. In the axial direction to the position shown in FIG.

The projection 7a interferes with the release lever 40 when the fixing unit 30 is not completely set on the apparatus main body 45 side as shown in FIG. It has become. As shown in FIG. 7, when the fixing unit 30 is completely set on the apparatus main body 45 side, the projection 7a abuts on the operation knob 5 without interfering with the release lever 40, and can be closed by the opening / closing cover 7. Become.

Next, the operation of the fixing unit 30 having the above configuration will be described.

First, as shown in FIG.
0 is inserted into the apparatus main body 45 from the side where the first driven gear 2 is located. At this time, if the fixing unit 30 is not completely set on the apparatus main body 45 side, even if the cover 7 is to be closed, the projection 7a of the cover 7 hits the release lever 40 and the cover 7 is closed. Can not.

When the fixing unit 30 is completely set on the apparatus main body 45 side by performing the inserting operation shown in FIG. 5, the fixing unit 30 is held at the position shown in FIG. In this position, the gear portion 5a of the operation knob 5 meshes with the second driven gear 6, and the relay gear 3 meshes only with the first driven gear 2 and does not mesh with the driving gear 4 on the apparatus body 45 side.

When the cover 7 is closed from the state shown in FIG. 2, the projection 7a abuts on the operation knob 5 without interfering with the release lever 40, and the rotating shaft 9 is opposed to the urging force of the elastic member 8 as shown in FIG. Axial direction until indicated position (direction of A in the figure)
Moved to At this position, the relay gear 3 meshes with the drive gear 4 on the device main body 45 side while maintaining the meshing state with the first driven gear 2, and the gear portion 5 a of the operation knob 5 is disengaged from the second driven gear 6. Therefore, the driving force of the motor M is transmitted from the driving gear 4 via the relay gear 3 to the first driven gear 2.
And the fixing roller 1 is rotated together with the rotating shaft 1a. As a result, the fixing unit 30 conveys the transfer material entering the nip portion between the fixing roller 1 and the pressure roller by the rotational force while simultaneously fixing the toner image carried on the transfer material to the transfer material by heat. It becomes possible.
At this time, both the relay gear 3 and the rotating shaft 9 rotate, but do not rotate because the operation knob 5 is in an idle state. Therefore, the protrusion 7a that comes into contact with the operation knob 5 does not wear.

If a jam (paper jam) in which the transfer material remains between the fixing roller 1 and the pressure roller during such driving of the fixing unit 30 occurs, a jam detector (not shown) operates to operate the motor. M stops, and the rotation of the fixing roller 1 stops. In this state, when the opening / closing cover 7 is opened to remove the transfer material from between the fixing roller 1 and the pressure roller, the pressing force of the projection 7 a against the operation knob 5 is released, and the urging force of the elastic member 8 is released. The rotation shaft 9 is shown in FIG.
Is forcibly moved in the axial direction (the direction of B in the figure) to the position of. As a result, the gear portion 5a meshes with the second driven gear 6, and the meshing state between the relay gear 3 and the driving gear 4 is released. Accordingly, when the operation knob 5 is turned in a predetermined direction in this state, the second driven roller 6 meshing with the gear portion 5a is rotated, and the fixing roller 1 is rotated together with the rotation shaft 1a, so that the transfer jammed between the rollers is caused. The material is removed. In addition,
In this case, since the first driven gear 2 is not meshed with the drive gear 4, the jam clearance can be performed with a small operation force without resisting the load of the drive-side transmission mechanism 32.

As described above, according to the drive contact / separation mechanism 47 of the fixing unit 30 of the present embodiment, the opening / closing cover 7
Is opened, the rotating shaft 9 is automatically moved, and the meshing state between the driving gear 4 and the relay gear 3, ie, the driving gear 4
Since the connection state between the fixing roller 1 and the driven gear 2 is released, the load of the transmission mechanism 32 on the driving side can be prevented.
The jam clearance can be performed only by rotating the operation knob 5. That is, there is no need to perform a two-stage operation of moving the rotary shaft 9 in the axial direction for jam clearance and rotating the rotary shaft 9 with the operation knob 5 as in the related art. It is not necessary to rotate the operation knob 5 against the load of the transmission mechanism 32, and the jam clearance can be performed with a light operation force by simply performing the one-stage operation of rotating the operation knob 5. Further, since the mechanism is simple and the number of parts is small, it is advantageous in terms of cost.

In the drive contact / separation mechanism 47 of the present embodiment, the protrusion 7a has not only a function of moving the rotating shaft 9 but also a function of the fixing unit 30 with respect to the apparatus main body 45 in cooperation with the release lever 40. It also has a function to notify the operator of the complete set state. Therefore, the release lever 40
There is no need to provide a separate projection on the opening and closing cover 7, which is advantageous in terms of cost.

FIG. 8 shows a modification of this embodiment.
In this modification, in a state where the opening / closing cover 7 is completely closed and the relay gear 3 and the drive gear 4 are in mesh with each other, the separation distance L1 between the gear portion 5a of the operation knob 5 and the second driven gear 6 is equal to the relay gear 3 Is set to be larger than the mesh width L2 between the gear and the drive gear 4. Therefore, in this configuration, when the opening / closing cover 7 is opened, the meshing state between the relay gear 3 and the drive gear 4 is completely released, and then the gear portion 5a of the operation knob 5 is released.
Are engaged with the second driven gear 6.

As described above, if the gear portion 5a and the second driven gear 6 are meshed after the meshing state between the relay gear 3 and the driving gear 4 is completely released, the driving gear 4 becomes If the opening / closing cover 7 is opened while applying rotational force to the gear 3 (during copying, etc.), the relay gear 3 is completely disengaged from the drive gear 4 and the drive in the unit 30 is stopped. The connection with the second driven gear 6 prevents the gear portion 5a and the second driven gear 6 from being damaged.

It is needless to say that the present invention is not limited to the above-described embodiment, but can be variously modified without departing from the gist thereof.

[0038]

According to the first aspect of the present invention, simply by opening the opening / closing cover, the holding means is automatically moved,
Since the connection state between the rotational force transmission means and the drive unit is released, that is, the connection state between the drive unit and the driven unit of the transfer material transport roller is released, without resisting the load of the drive side transmission mechanism,
The jam processing can be performed only by operating the turning force applying means.

According to the second aspect of the present invention, the transfer device for transferring the transfer material can be designed compact.

According to the third aspect of the present invention, there is no need to separately provide a means for preventing the opening / closing cover from closing the opening / closing cover, which is advantageous in cost.

According to the fourth aspect of the present invention, when the opening / closing cover is opened while the driving section is applying the rotational force to the rotational force transmitting means (during copying, etc.), the rotational force transmitting means is driven. Since the rotational force applying means is connected to the driven part after the transfer material transport roller is completely stopped from being detached from the part, the rotational force applying means and the driven part are prevented from being damaged.

According to the fifth aspect of the present invention, simply by opening the opening / closing cover, the rotating shaft is automatically moved and the connection between the relay gear and the driving gear is released, that is, the driving gear and the fixing roller are disengaged. Since the connection state with the first driven gear is released, the jam clearance can be performed only by turning the operation knob without resisting the load on the transmission mechanism on the driving side.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part illustrating a first state of a fixing unit including a drive contact / separation mechanism according to an embodiment of the present disclosure.

FIG. 2 is a cross-sectional view of a main part showing a second state of the fixing unit including the driving contact / separation mechanism according to the embodiment of the present invention.

FIG. 3 is a perspective view showing a fixing unit and an image forming apparatus main body of FIGS. 1 and 2;

FIG. 4 is a cross-sectional view showing one end of a rotation shaft of the drive contact / separation mechanism.

FIG. 5 is a perspective view showing a state where the fixing unit of FIG. 1 is pulled out from the apparatus main body side.

FIG. 6 is a plan view schematically showing a state in which the opening / closing cover is closed in a state where the fixing unit of FIG. 1 is not completely inserted into the apparatus main body.

FIG. 7 is a plan view schematically showing a state in which the opening / closing cover is closed in a state where the fixing unit of FIG. 1 is completely inserted into the apparatus main body side.

FIG. 8 is a sectional view showing a modified example of the drive contact / separation mechanism of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixing roller (transfer material conveyance roller) 1a Rotary shaft 2 1st driven gear (driven part) 3 Relay gear (rotational force transmission means) 4 Drive gear (drive part) 5 Operation knob (rotational force applying means) 5a Gear part 6 Second driven gear (driven portion) 7 Opening / closing cover 7a Projection (pressing means) 8 Elastic member (biasing means) 9 Rotary shaft (holding means)

Claims (5)

[Claims] An image forming apparatus is provided in an image forming apparatus having a transfer material conveying roller for sending and transferring a transfer material in a predetermined direction, and a driving unit for applying a rotational force to the transfer material conveying roller. In a drive contact / separation mechanism for detachably connecting a driven unit fixed to a shaft and the drive unit, the drive unit is connected to both the drive unit and the driven unit, and transmits a rotational force of the drive unit to the driven unit. A force transmitting means, connected to the driven part, a rotating force applying means for applying a rotating force to the driven part, and a rotating force transmitting means and a rotating force applying means, wherein the rotating force transmitting means is connected to the driving part and the driven part. A rotational force transmitting position to be connected, and a holding means capable of moving between a rotational force transmitting position and a rotational force input position where the rotational force applying means is disconnected from the driven part and the rotational force transmitting means is disconnected from the driving unit; Biasing the holding means toward the torque input position Means, provided on an opening / closing cover for opening / closing a portion where the transfer material transporting roller is located, and pressing the holding means against the urging force of the urging means when the opening / closing cover is closed toward the rotational force transmitting position. And pressing means for releasing the pressing force on the holding means when the opening / closing cover is opened to allow the urging means to move the holding means to the rotational force input position. Drive contact and separation mechanism. 2. The drive contact / separation mechanism according to claim 1, wherein the drive contact / separation mechanism and the transfer material conveying roller constitute one unit detachably attached to a main body of the image forming apparatus. . 3. A main body of the image forming apparatus has a release lever for releasing the mounting of the unit, and the pressing means operates when the unit is not completely attached to the main body of the image forming apparatus. The drive contact / separation mechanism according to claim 2, wherein the opening / closing cover is prevented from being closed by contacting the release lever. 4. The drive contact / separation mechanism according to claim 1, wherein the rotational force applying unit is connected to the driven unit after the connection between the rotational force transmitting unit and the driving unit is released. 5. A fixing unit of an image forming apparatus for fixing a toner image onto a transfer material, comprising: a rotatable fixing roller containing a predetermined heat source; and a first driven member provided at one end of a rotation shaft of the fixing roller. A second driven gear provided on the other end side of the rotating shaft of the fixing roller; and a driving gear meshed with both a driving gear and a first driven gear provided on an apparatus body of the image forming apparatus. A relay gear that transmits the rotational driving force of the first driven gear to the rotating shaft of the fixing roller via a first driven gear, an operation knob having a gear portion that meshes with the second driven gear, and a relay gear at one end thereof. An operation knob is rotatably held at the other end, a rotational force transmitting position at which the relay gear meshes with the drive gear and the first driven gear, a meshing state between the relay gear and the drive gear is released, and the gear of the operation knob is released. Is engaged with the second driven gear A rotating shaft portion movable between a rotating force input position and a biasing unit for biasing the rotating shaft portion toward the rotating force input position, wherein the rotating shaft portion opens and closes the image forming apparatus. When the cover is closed, it is pressed by the projection provided on the opening / closing cover, and is moved toward the rotational force transmitting position against the urging force of the urging means. A fixing unit, wherein the pressing force is released and the urging means moves to a rotational force input position.