JP4329580B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to a fixing device including a nip release lever that releases a nip between a heat roller and a press roller.

  Image forming apparatuses such as copiers, facsimiles, and printers are equipped with a jam access cover that can be opened and closed for maintenance work such as removing paper jams. By opening the cover, the recording paper conveyance path inside the apparatus is accessed. Possible configurations are known.

  Also, when performing maintenance work with the jam access cover open, operate the nip release lever that releases the nip between the heat roller and press roller of the fixing unit inside the image forming device to release the nip between both rollers. A technique is known in which at least one of the rollers is free to rotate so that the recording paper jammed inside the fixing device can be easily pulled out and removed (see, for example, Patent Document 1).

JP 2000-338815 A

  The present invention has a configuration different from that of the prior art, and when the jam access cover is opened, the cover opening / closing of the nip release lever is such that the side of the engaging portion provided on the cover on the opening side of the cover opening / closing direction is at the nip position. When the nip release lever is in the nip position when the cover is closed by moving the nip release lever from the nip position to the nip release position in the cover opening / closing direction The nip release lever is moved from the nip position along the moving path of the engagement portion while the side portion of the engagement portion on the closed side in the cover opening / closing direction is in contact with the side portion of the nip release lever on the opening side in the cover opening / closing direction. The fixing device is configured to be displaced to the avoidance position and pass through the engaging portion, and includes a nip release lever that can move laterally with respect to the opening and closing direction of the cover when passing through the engaging portion. It is an object to provide a fixing device was.

The problems to be solved by the present invention are as described above. Next, means for solving the problems will be described.
First, as described in claim 1, an image forming apparatus main body, a fixing device that is disposed in the image forming apparatus main body and includes a heat roller, a press roller, and a nip release lever, and the fixing device A cover that covers and can be opened and closed by rotating with respect to the image forming apparatus main body, and an engaging portion that is suspended from the cover toward the image forming apparatus main body and is arranged in a shape in which an F-shape is laid down The nip release lever from a nip position that nips the heat roller and the press roller to a nip release position that releases the nip between the heat roller and the press roller. It is configured to rotate with respect to the shaft, and to be displaced in the roller axial direction from the nip position to an avoidance position where the nip release lever avoids engagement with the engagement portion. , The roller axis is made parallel to the axial direction to open and close pivoting of the cover, when opening the cover, and the engaging portion is engaged with the nip release lever, the nip position the nip release lever In the image forming apparatus that is rotated from the nip release position to the nip release position, the avoidance of the nip release lever toward the axis for opening and closing the cover on the side surface opposite to the avoidance position in the roller axis direction. A guide portion that is inclined toward the position side; and a biasing means that biases the nip release lever from the avoidance position toward the nip position between the press roller and the nip release lever; and When closing, when the nip release lever is in the nip position, one side of the engagement portion contacts the guide portion of the nip release lever. Reluctant to displace the said nip release lever to the avoidance position from the nip position.

Moreover, as described in claim 2,
Chamfered said cover opening and closing direction opening side edge of the guide portion.

And as described in claim 3,
The avoidance position side of the side in the roller axis direction of the engagement portion, provided with a guide portion inclined him to go into the cover opening and closing direction close side to the anti-evasive position.

Since the present invention is configured as described above, the following effects can be obtained.
In the first aspect of the present invention, when the nip release lever is in the nip position when the cover is closed, the side portion of the engagement portion on the closing side of the cover opening / closing direction is the side of the nip release lever. The nip release lever can be smoothly moved in the lateral direction with respect to the cover opening / closing direction by pushing the guide portion in the lateral direction with respect to the cover opening / closing direction while being in contact with the guide portion. Thereby, the nip release lever can move from the nip position to the avoidance position and pass through the engaging portion. With this configuration, the stroke of the nip release lever in the cover opening / closing direction can be shortened, and the fixing device can be made compact.

  Further, in the invention according to claim 2, by chamfering the edge portion of the guide portion on the opening side of the cover opening / closing direction, an impact at the time of contacting the guide portion of the nip release lever is reduced, and the engagement is performed. Damage to both the nip release lever and the nip release lever is prevented.

  According to a third aspect of the present invention, when the nip release lever is in the nip position when the cover is closed, the guide portion of the engaging portion is in contact with the guide portion of the nip release lever. The guide portion of the nip release lever can be smoothly guided laterally with respect to the cover opening / closing direction. Thereby, the nip release lever can move from the nip position to the avoidance position and pass through the engaging portion.

Next, an embodiment of the present invention will be described with reference to the drawings.
First, an image forming apparatus 1 included in a copier, a facsimile machine, or the like will be schematically described with reference to FIGS. 1 and 2.

  As shown in FIG. 1, the image forming apparatus 1 is disposed above the paper feed cassette 5, and a paper discharge tray 6 is formed on the upper part of the image forming apparatus 1. Inside the image forming apparatus 1, there are formed a first recording paper transport path 11 and a second recording paper transport path 12 for transporting the recording paper fed from the paper feed cassette 5, and the first recording paper A developing unit 2, a photosensitive unit 3, and a fixing unit 4 are arranged along the transport path 11 toward the downstream side. These units 2, 3, 4 constitute an image forming unit, and the recording paper fed from the paper feed cassette 5 is discharged after image information is transferred and fixed by the image forming unit. It is configured to be discharged to the tray 6.

  A jam access cover 7 is provided at one side portion of the image forming apparatus 1 so as to be openable and closable (rotatable) with respect to the apparatus main body 1 a, and the jam access cover 7 is a lower part of one side end portion of the image forming apparatus 1. The image forming apparatus 1 is configured to be capable of rotating up and down around the position so that one side of the image forming apparatus 1 can be opened when a jam occurs in the recording paper transport paths 11 and 12.

  The fixing unit 4 is disposed on the upper part of the image forming apparatus 1 and is detachably attached between the apparatus main body 1a and the jam access cover 7. When the fixing unit 4 is attached to the apparatus main body 1a, the fixing unit 4 is mounted on the apparatus main body 1a. The second recording paper transport path 12 is formed between the outer side of the fixing unit 4 and the inner side of the jam access cover 7. The second recording paper transport path 12 is a transport path for reversing the paper surface of the recording paper during double-sided printing, and is disposed on the outer side (jam access cover 7 side) of the first recording paper transport path 11. The first recording paper transport path 11 and the second recording paper transport path 12 are configured to branch at a branch section 11b on the downstream side of the image forming section and to join at a junction section 11a on the upstream side of the image forming section. ing.

Next, the configuration of the fixing unit 4 will be described.
As shown in FIG. 1, the fixing unit 4 includes a heat roller 41 in which a lamp heater 48 such as a halogen lamp is installed at an axial center position, and a press roller 42 that presses against the heat roller 41, and the fixing unit 4. When the container unit 4 is attached to the apparatus main body 1 a, the nip portion between the heat roller 41 and the press roller 42 is arranged along the first recording paper conveyance path 11.

  As shown in FIGS. 2 and 3, the frame of the fixing unit 4 includes a first frame 43 that supports the heat roller 41 and a second frame 44 that supports the press roller 42, and the first frame. The lower end of 43 and the lower end of the second frame 44 are engaged, and the upper end of the first frame 43 and the upper end of the second frame 44 are fastened.

  Coil springs (not shown) for urging the roller shaft of the press roller 42 toward the heat roller 41 are attached to both ends of the second frame 44 in the roller axis direction, and the press roller 42 is attached to the heat roller 41 by the coil spring. Press contact.

  As shown in FIGS. 1 and 3, a switching member 45 that switches the conveyance direction of the recording paper is rotatably attached to the upper portion of the second frame 44. The position of the center of gravity of the switching member 45 is disposed on the first frame 43 side with respect to the rotation shaft 45a of the switching member 45. For this reason, the switching member 45 is tilted toward the first frame 43 by its own weight. . Further, a torsion spring 46 is attached to the rotating shaft 45a of the switching member 45, and the torsion spring 46 also urges the switching member 45 lightly so as to surely fall down to the first frame 43 side.

  As shown in FIGS. 4 and 5, the switching member 45 has a large number of ribs 45 b, 45 b... Protruding around the rotating body 45 c in the roller axis direction, and the second frame 44. A number of ribs 44b, 44b,... The ribs 44b, 44b,... And the ribs 45b, 45b,... Reduce the contact area with the recording paper to reduce the frictional resistance so that the recording paper is smoothly conveyed.

  As shown in FIG. 1, the switching member 45 normally falls to the first frame 43 side with the branching portion 11b closing the first recording paper transport path 11 and opening the entrance to the second recording paper transport path 12. The recording paper that has passed through the fixing unit 4 passes through the branching portion 11b while pushing up the switching member 45 at the leading end. After the end of the recording paper passes through the branching portion 11b, the switching member 45 is The position is configured to return to a state in which the first recording paper transport path 11 is blocked and the entrance to the second recording paper transport path 12 is opened. When there is a recording sheet that has passed through the branching portion 11 b and has been switched back, the recording sheet is guided to the second recording sheet conveyance path 12 by the upper portion of the switching member 45.

  As shown in FIGS. 3, 4, and 5, nip release levers 50 that release the nip between the heat roller 41 and the press roller 42 are provided at both ends of the second frame 43 in the roller axial direction. The nip release lever 50 is configured to rotate in conjunction with opening and closing of the jam access cover 7, thereby improving convenience.

Next, the configuration of the nip release lever 50 will be described.
As shown in FIGS. 6, 7, and 8, the head 50 a of the nip release lever 50 has a roller axial direction outer side (a side on the anti-avoidance position side to be described later) and a cover opening / closing direction opening side. Accordingly, a guide portion 50c having a side surface inclined inward in the roller axis direction (avoidance position side) is formed. Further, the head 50a of the nip release lever 50 is formed with an abutting portion 50d having an upper surface that is inclined downward as it goes to the opening side of the cover opening / closing direction.

  As shown in FIG. 9, the base 50b of the nip release lever 50 is formed with a long hole 50h that is long in the vertical direction. The long hole 50h of the base 50b is formed of a metal member such as iron or aluminum or a resin. The press roller 42 is attached to a roller shaft 49. That is, the roller shaft of the press roller 42 and the rotation shaft of the nip release lever 50 that pulls the press roller 42 away from the heat roller 41 are configured by a common shaft 49 (hereinafter referred to as “common shaft 49”). According to this configuration, the number of parts can be reduced to reduce the cost, and unnecessary moment is not generated in the fixing unit 4 when the nip release lever 50 is rotated.

The base portion 50b of the nip release lever 50 includes a nip release surface 50f that is a region having a relatively long distance from the axis of the common shaft 49 (or the central position where the major axis and minor axis of the long hole 50h intersect). The nip surface 50g is a region having a relatively short distance from the axis of the common shaft 49, and is formed into a cam shape.
As described above, the nip release lever 50 includes the head portion 50a, the base portion 50b, and the arm portion 50e that connects the head portion 50a and the base portion 50b, and the edges thereof are chamfered.

Next, a configuration in which the nip release lever 50 rotates in conjunction with opening / closing of the jam access cover 7 will be described.
As shown in FIG. 9, the frame 70 constituting the jam access cover 7 includes a first engagement portion 70 a that engages with and disengages from the nip release lever 50, and a second engagement portion 70 b at both ends in the roller axial direction. Are provided in pairs. The second engaging portion 70b is disposed on the opening side of the first engaging portion 70a in the cover opening / closing direction, and the first engaging portion 70a and the second engaging portion 70b are suspended from the frame 70 in parallel. Thus, the “F” shape is placed in a lying shape.

  9, 10, and 11, when the jam access cover 7 is opened, the side of the first engagement portion 70 a of the jam access cover 7 on the opening side in the cover opening / closing direction is at the nip position. The nip release lever 50 is configured to rotate from the nip position to the nip release position in the cover open / close direction by being pressed against the side of the head 50a of the release lever 50 on the closed side of the cover open / close direction. ing. As a result, the base 50b of the nip release lever 50 rotates (clockwise in FIGS. 9, 10, and 11), and the nip release surface 50f of the base 50b faces the base 50b. The nip between the heat roller 41 and the press roller 42 is released by contacting the base receiving portion 43b of the first frame 43 and relatively separating the distance between the common shaft 49 and the roller shaft of the heat roller 41. The

  As shown in the order of FIGS. 11, 12, and 9, if the nip release lever 50 is in the nip release position when the jam access cover 7 is closed, the second engaging portion of the jam access cover 7 The side portion of the cover 70b in the cover opening / closing direction closed side contacts the contact portion 50d which is the side portion of the head portion 50a of the nip release lever 50 on the cover opening / closing direction opening side, whereby the nip release lever 50 is moved to the nip release position. It is configured to rotate in the cover opening / closing direction from the nip position to the nip position. As a result, the base 50b of the nip release lever 50 rotates (rotates counterclockwise in FIGS. 11, 12, and 9), and the nip surface 50g of the base 50b and the base receiving portion 43b of the first frame 43 Are opposed to each other and the distance between the common shaft 49 and the roller shaft of the heat roller 41 is relatively close, whereby the heat roller 41 and the press roller 42 are nipped.

  In this state, a gap is formed between the nip surface 50g of the base 50b of the nip release lever 50 and the base receiving portion 43b of the first frame 43, and the nip release lever 50 with respect to the cover opening / closing direction due to the gap. It can be displaced in the direction of the roller axis, which is the lateral direction. In this state, the long hole 50h formed in the base portion 50b of the nip release lever 50 is vertically long, and the common shaft 49 inserted through the long hole 50h has a circular cross-sectional shape. Therefore, the nip release lever Reference numeral 50 denotes a nip position (specifically, in a section between the nip position and an avoidance position described later) and can be tilted in the roller axis direction.

As described above, the nip release lever 50 is configured to rotate in conjunction with opening and closing of the jam access cover 7.
However, before the jam access cover 7 is closed, the user may manually return the nip release lever 50 to the nip position. In this case, the nip release lever 50 is operated as follows. The first engaging portion 70a is dodged.

  As shown in the order of FIGS. 13, 14, and 9, when the nip release lever 50 is in the nip position when the jam access cover 7 is closed, the cover of the first engagement portion 70 a of the jam access cover 7 is covered. The nip release lever 50 is displaced from the nip position to the avoidance position in the roller axis direction while the side portion on the closing side of the opening / closing direction is in contact with the guide portion 50c which is the side of the nip release lever 50 on the opening side of the cover opening / closing direction. Thus, the first engaging portion 70a is configured to be overtaken (avoided).

Next, a configuration in which the nip release lever 50 passes over the first engagement portion 70a of the jam access cover 7 will be described.
As shown in FIGS. 6 and 15, a nip release lever 50 is provided between the nip position and the nip release position in the cover opening / closing direction at both ends of the second frame 44 supporting the press roller 42 in the roller axial direction. A first guide groove 44c to be guided and a second guide groove 44d to be guided in the roller axial direction between the nip position and an avoidance position that avoids the movement path of the first engagement portion 70a of the jam access cover 7 are formed. ing. The nip position and the avoidance position are arranged along the roller axis direction but are different from each other , and the avoidance position is arranged on the center side in the longitudinal direction of the roller with respect to the nip position, and the nip release lever 50 is configured to be displaced within the width of the fixing unit 4 in the roller axial direction, and the size of the fixing unit 4 in the roller axial direction is made compact. The corner of the connecting portion to which the first guide groove 44c and the second guide groove 44d are connected is chamfered, and the chamfered portion 44e is C chamfered in the present embodiment, but as shown in FIG. The chamfer 44f may be an R chamfer.

  In this way, by chamfering the corner of the connecting portion where the first guide groove 44c and the second guide groove 44d are connected, the nip release lever 50 is smoothly changed between the cover opening / closing direction and the roller axial direction. And the nip release lever 50 does not break the corners of the connection.

  Further, as shown in FIG. 7, the edge portion 50k on the side surface of the nip release lever 50 on the side of the avoidance position in the roller axis direction is also chamfered, and this portion is chamfered by the chamfered portions 44e and 44f in the cover opening / closing direction and the roller axis direction. The nip release lever 50 is configured to be smoothly guided when the direction is changed between the nip release lever 50 and the nip release lever 50.

  As shown in FIGS. 6 and 17, a coil spring 52 for urging the nip release lever 50 from the avoidance position toward the nip position is provided below the guide grooves 44c and 44d. A spring receiver 53 is attached to the common shaft 49 between the nip release lever 50 and the press roller 42, and a space 44f is provided between the spring receiver 53 and the base 50b of the nip release lever 50 at the nip position. The coil spring 52 is formed on the common shaft 49 in the space 44f. The length of the coil spring 52 in the roller axis direction (the length from the avoidance position toward the nip position) is configured to be equal to or longer than the length of the space 44f in the roller axis direction. With such a configuration, the coil spring 52 as the urging means is provided in the space 44f between the nip release lever 50 and the press roller 42, and is summarized in a compact layout.

As shown in FIG. 18, the side of the first engagement portion 70 a provided on the jam access cover 7 on the side of the avoidance position in the roller axial direction moves toward the counter-avoidance position as the cover opens and closes in the closing direction. An inclined guide part 70c is formed.
As shown in FIGS. 19, 20, and 21, when the nip release lever 50 is in the nip position when the jam access cover 7 is closed, the guide portion of the first engagement portion 70 a of the jam access cover 7 is used. While 70c is in contact with the guide portion 50c of the head 50a of the nip release lever 50, the nip release lever 50 is smoothly guided from the nip position to the avoidance position along the second guide groove 44d in the roller axis direction. The nip release lever 50 is displaced to the center in the longitudinal direction of the roller and tilted while the first engaging portion 70a is passed over.

  As shown in FIGS. 7 and 8, the arm portion 50e that connects the head portion 50a and the base portion 50b of the nip release lever 50 is configured to be relatively long. Therefore, the nip release lever 50 is displaced in the roller axial direction. Sometimes the force applied to the guide portion 50c of the head 50a can be small. In addition, by configuring the arm portion 50e to be long, the first engagement portion 70a of the jam access cover 7 can be passed by simply tilting the nip release lever 50 without substantially displacing the position of the base portion 50b. The distance between the nip position and the avoidance position in the second guide groove 44d can be shortened, and the avoidance configuration of the nip release lever 50 can be made compact.

  As shown in FIGS. 6 and 7, the edge portion 50 m of the guide portion 50 c of the nip release lever 50 on the opening side in the cover opening / closing direction is also chamfered, whereby the first engagement portion 70 a of the jam access cover 7 is chamfered. The impact when the guide portion 70c and the guide portion 50c of the nip release lever 50 come into contact with each other is alleviated, and both the first engagement portion 70a and the nip release lever 50 are prevented from being damaged.

  With such a configuration, after closing the jam access cover 7, after the nip release lever 50 at the nip position is displaced from the nip position to the avoidance position and the first engaging portion 70a of the jam access cover 7 is passed over. The nip release lever 50 can be reliably returned from the avoidance position to the nip position by the coil spring 52, and the nip release lever 50 is urged to the counter-avoidance position side by the coil spring 52 after returning to the nip position. Also, it does not tilt in the roller axis direction. For this reason, the first engagement portion 70a of the jam access cover 7 and the head 50a of the nip release lever 50 are surely brought into contact with each other even when the cover is opened and closed, and the nip release lever 50 is released from the nip position. As a result of the reliable movement to the position, the reliability is improved.

  Further, the length of the coil spring 52 as the biasing means in the roller axial direction is equal to or longer than the length of the space 44f in the roller axial direction. The lever 50 is moderately biased so as not to tilt in the roller axis direction, and also when the jam access cover 7 is closed, when the nip release lever is in the nip position, the nip release lever 50 is moved away from the nip position. It works to the extent that it does not hinder displacement to the avoidance position. The nip release lever 50 can be reliably returned from the avoidance position to the nip position by the coil spring 52 after the first engaging portion 70a of the jam access cover 7 has been passed.

1 is a front sectional view showing a schematic configuration of an image forming apparatus 1. FIG. FIG. 3 is a perspective view of the fixing unit 4. FIG. 4 is a side view of the fixing unit 4. FIG. 3 is a plan view of the fixing device unit 4. FIG. 3 is a rear view of the fixing unit 4. 4 is a perspective view of a nip release lever 50 provided on one side of the fixing unit 4 in the roller axial direction. FIG. The perspective view which looked at the nip release lever 50 from the cover opening / closing direction opening side. The perspective view which looked at the nip release lever 50 from the cover open / close direction closed side. FIG. 4 is a side cross-sectional view of the fixing unit 4 with the jam access cover 7 closed. FIG. 3 is a side sectional view of the fixing unit 4 when the jam access cover 7 is opened. FIG. 3 is a side sectional view of the fixing unit 4 when the jam access cover 7 is opened. FIG. 3 is a side sectional view of the fixing unit 4 when the jam access cover 7 is closed. FIG. 3 is a side sectional view of the fixing unit 4 when the jam access cover 7 is closed. FIG. 3 is a side sectional view of the fixing unit 4 when the jam access cover 7 is closed. FIG. 3 is a plan view showing one side of the fixing unit 4 in the roller axial direction. FIG. 3 is a plan view showing one side of the fixing unit 4 in the roller axial direction. FIG. 6 is a bottom cross-sectional view showing one side of the fixing unit 4 in the roller axial direction. FIG. 3 is a plan view showing one side of the fixing unit 4 in the roller axial direction. FIG. 3 is a plan view showing one side of the fixing unit 4 in the roller axial direction. FIG. 3 is a plan view showing one side of the fixing unit 4 in the roller axial direction. FIG. 3 is a plan view showing one side of the fixing unit 4 in the roller axial direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 4 Fixing unit 7 Jam access cover 41 Heat roller 42 Press roller 43 1st frame 43b Base receiving part 44 2nd frame 44c 1st guide groove 44d 2nd guide groove 44e Chamfer 44f Chamfer 49 Common shaft 50 Nip release lever 50a Head portion 50b Base portion 50c Guide portion 50d Contact portion 50e Arm portion 50f Nip release surface 50g Nip surface 50h Long hole 52 Coil spring 53 Spring receiver 70 Frame 70a First engagement portion 70b Second engagement portion 70c Guide portion

Claims (3)

An image forming apparatus main body;
A fixing device that is disposed in the image forming apparatus main body and includes a heat roller, a press roller, and a nip release lever;
A cover that covers the fixing device and can be opened and closed by rotating with respect to the image forming apparatus main body ;
An engaging portion that is suspended in the cover toward the image forming apparatus main body and is arranged in a shape in which an F-shape is laid down;
With
The nip release lever rotates with respect to the roller shaft of the press roller from a nip position where the heat roller and the press roller are nipped to a nip release position where the nip between the heat roller and the press roller is released. Configured to move in the roller axis direction from the nip position to an avoidance position where the nip release lever avoids engagement with the engagement portion,
The roller shaft is parallel to the axial direction of opening and closing of the cover,
In the image forming apparatus, when the cover is opened, the engaging portion engages with the nip release lever and rotates the nip release lever from the nip position to the nip release position .
On the side surface of the nip release lever opposite to the avoidance position in the roller axis direction, a guide portion is provided that inclines toward the avoidance position side toward the shaft that opens and closes the cover .
An urging means for urging the nip release lever from the avoidance position toward the nip position is provided between the press roller and the nip release lever;
When closing the cover, if the nip release lever is in the nip position, the nip release lever is moved away from the nip position while one side of the engagement portion is in contact with the guide portion of the nip release lever. Displace to the position ,
An image forming apparatus. Chamfered the edge of the guide portion on the opening side of the cover opening and closing direction,
The image forming apparatus according to claim 1. Provided on the side of the engagement portion on the side of the avoidance position in the roller axial direction is a guide portion that is inclined toward the counter-avoidance position as the cover opens and closes in the closing direction.
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.

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