JP2004286774A - Fixing unit and its assembling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing unit whose number of parts is reduced so that work at the time of jamming or assembling is easily performed, and its assembling method. <P>SOLUTION: A peeling pawl 86 is turnably supported in a housing 66. At the time of assembling the fixing unit, the pawl 86 is retreated from a housing part for a heating roll 72 by abutting on a tool for retreating 128 before the roll 72 is housed. After the roll 72 is housed in the housing 66, the tool 128 is removed and the pawl 86 is made to abut on the roll 72. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fixing unit and a method for assembling the fixing unit.
[0002]
2. Description of the Related Art For example, in an electrophotographic image forming apparatus, a fixing device is used to fix toner on a recording medium. As one of the fixing devices, the fixing device includes a heating roller and a pressure roller for pressing the heating roller. The recording medium is passed between the heating roller and the pressure roller, and the toner on the recording medium is heated and pressured. What is fixed by is well known. Further, as such a fixing device, a fixing device in which the fixing device is unitized so as to be easily attached to and detached from the image forming apparatus (hereinafter, referred to as a fixing unit) is also known.
[0003] As a fixing unit, a heating roll, a pressure roll, and a peeling claw are mounted on a housing, a plate-shaped roll pressing body is covered from above the housing, and the roll pressing body is latch-engaged with the housing. 2. Description of the Related Art A fixing unit is known (for example, Patent Document 1). Further, as another fixing unit, a heating roll is supported on the first housing, a pressure roll is supported on the housing on the second housing, and the first housing and the second housing are fixed by a latch unit. The following is known (for example, Patent Document 2).
[0004]
[Patent Document 1] Japanese Patent No. 3343404 [Patent Document 2] Japanese Patent Application Laid-Open No. 6-348164
[Problems to be solved by the invention]
However, in the conventional fixing unit, the peeling claw is provided separately from a housing on which a fixing roll (in this specification, when a heating roll and a pressure roll are not distinguished from each other, both are referred to as a fixing roll). A mounting structure is employed in which the structure, which is supported by the structure and has the peeling claw mounted thereon, is further mounted on the housing, and there is a problem that it is difficult to reduce the number of components. In order to reduce the number of parts, it is conceivable to provide the peeling claw directly on the housing and omit the structure supporting the peeling claw. However, if the peeling claw is simply attached to the housing, the peeling claw may easily fall off the housing when an operator or a recording medium touches the peeling claw during a jam or the like. For this purpose, it is desirable that the peeling nail is assembled before the fixing roll is assembled, and it is desirable that the peeling nail is overlapped with the fixing roll. There is a problem that it becomes an obstacle, and the work of attaching the fixing roll to the housing becomes difficult.
An object of the present invention is to provide a fixing unit capable of reducing the number of parts. Another object of the present invention is to provide a fixing unit capable of preventing a component from falling off when a recording medium is removed in the event of a jam, and capable of easily performing an assembling operation.
[0007]
Means for Solving the Problems To achieve the above object, a first feature of the present invention is that a fixing roll, a peeling claw abutting on the fixing roll, and the fixing roll are housed. A peeling claw is rotatably supported, and a surface facing one side of the fixing roll is opened and the other surface supporting the peeling claw is closed, and the peeling claw is prevented from dropping from the housing. The fixing unit includes a falling-off preventing unit. Therefore, since the peeling claw is provided in the housing, it is possible to reduce the number of components, and since a peeling prevention means for preventing the peeling claw from falling off the housing is provided, the peeling claw can be used in the case of a jam or the like. It can be prevented from falling off and the work can be facilitated.
The drop-off preventing means includes a notch formed by cutting a peripheral surface of the support shaft of the peeling claw, and an insertion portion having a width substantially equal to a width of the support shaft in a diameter direction of the notch. And a support groove formed in the support groove.
It is preferable that the apparatus further comprises a retracting means for retracting the peeling claw so that the fixing roll can be inserted into the housing. By providing such a retracting means, the peeling claw can be prevented from obstructing the assembling of the fixing unit, and the work at the time of assembling can be facilitated.
The retracting means may be constituted by means such as a latch provided in the housing, but may be configured to retract and support the peeling claw only during assembly. That is, a jig support portion for supporting a retreating jig for retreating the peeling claw is provided so that the fixing roll can be inserted into the housing, and the retreating jig is attached only at the time of assembly. The tool may be removed. Therefore, in this case, since the evacuation unit is not provided when the fixing unit is used, the peeling claw is erroneously used while being held at the evacuation position, and an unexpected problem (for example, a jam due to winding of the recording medium around the fixing roll). Can be prevented from occurring.
According to a second feature of the present invention, a retracting step of retracting the peeling claw rotatably supported by the housing and a storing step of storing the fixing roll in the housing after retracting the peeling claw. And a returning step of returning the peeling claw so as to contact the fixing roll after storing the fixing roll.
In the retracting step, it is preferable to use a retracting jig for holding the peeling claw at a retracted position.
[0013]
Embodiments of the present invention will now be described with reference to the drawings.
FIG. 1 shows an outline of an image forming apparatus 10 according to an embodiment of the present invention. The image forming apparatus 10 has an image forming apparatus main body 12, an image forming unit 14 is mounted in the image forming apparatus main body 12, and a discharge unit 16 is provided at an upper portion of the image forming apparatus main body 12. In the lower part of the image forming apparatus main body 12, for example, two-stage paper feed units 18, 18 can be arranged.
Each paper supply unit 18 has a paper supply unit main body 20 and a paper supply cassette 22 for storing a recording medium. The paper feed cassette 22 is slidably mounted on the paper feed unit main body 20, and is pulled out in a front direction (right direction in FIG. 1). Further, a pickup roll 24 is disposed in the upper portion near the back end of the sheet cassette 22, and a retard roll 26 and a feed roll 28 are disposed behind the pickup roll 24.
The transport path 32 is a recording medium path from the pickup roll 24 of the lowermost sheet feeding unit 18 to the discharge port 34. The transport path 32 is located on the back surface of the image forming apparatus main body 12 (the left side surface in FIG. 1). ), A portion which is formed substantially vertically from the pickup roll 24 of the sheet feeding unit 18 at the lowermost end to a fixing unit 36 described later. A transfer device 42 and an image carrier 44, which will be described later, are disposed on the upstream side of the fixing unit 36 in the transport path 32, and a registration roll 38 is disposed on the upstream side of the transfer device 42 and the image carrier 44. Further, a discharge roll 40 is disposed near the discharge port 34 of the transport path 32.
Accordingly, the recording medium sent out from the paper supply cassette 22 of the paper supply unit 18 by the pickup roll 24 is separated by the retard roll 26 and the feed roll 28, guided to the transport path 32, and temporarily stopped by the registration roll 38. Then, the developer image is transferred at a timing between a transfer device 42 and an image carrier 44, which will be described later, and the transferred developer image is fixed by the fixing unit 36 and discharged by the discharge roll 40. It is discharged from 34 to the discharge section 16.
However, in the case of double-sided printing, it is returned to the reversing path. That is, a portion of the transport path 32 before the discharge roll 40 is divided into two forks, a switching claw 46 is provided at the divided portion, and a reversing path 48 that returns from the divided portion to the registration roll 38 is formed. The reversing path 48 is provided with transport rolls 50a to 50c. In the case of double-sided printing, the switching claw 46 is switched to the side where the reversing path 48 is opened, and the rear end of the recording medium is applied to the discharge roll 40. At this point, the discharge roll 40 is reversed, and the recording medium is guided to the reversing path 48, and is discharged from the discharge port 34 to the discharge unit 16 through the registration roll 38, the transfer device 42, the image carrier 44, and the fixing unit 36. It is.
The image forming means 14 is of an electrophotographic type, and includes an image carrier 44 made of a photoreceptor, a charging device 56 made of, for example, a charging roll for uniformly charging the image carrier 44, and a charging device 56. An optical writing device 58 for writing a latent image on the charged image carrier 44 by light, and a developing device 60 having a developing roll for visualizing the latent image on the image carrier 44 formed by the optical writing device 58 with toner And a transfer device 42 formed of, for example, a transfer roll for transferring the toner image by the developing device 60 to a recording medium, a cleaning device 62 for cleaning the toner remaining on the image carrier 44, and a recording medium transferred by the transfer device 42 And a fixing unit 36 for fixing the upper toner image on the recording medium. The optical writing device 58 is composed of, for example, a scanning laser exposure device, and traverses a process cartridge 64 described later to form a latent image on the image carrier 44.
The optical writing device 58 can use an LED, a surface emitting laser, or the like as another embodiment.
The process cartridge 64 integrates the image carrier 44, the charging device 56, the developing device 60 and the cleaning device 62, and these can be exchanged as one. The process cartridge 64 can be removed from the image forming apparatus main body 12 by opening the discharge unit 16.
FIGS. 2 to 5 show details of the fixing unit 36. FIG. The fixing unit 36 has a first housing 66 and a second housing 68. The first housing 66 and the second housing 68 are rotatably supported via a housing fulcrum 70 (shown in FIG. 5).
The heating roll 72 is provided on the first housing 66. The first housing 66 is formed, for example, in a U-shape in cross section, and has one side on which the heating roll 72 is inserted opened and the other side closed. The heating roll 72 has a cylindrical roll portion 74 and a heater 76 disposed in the roll portion 74. The roll portion 74 is supported by the first housing 66 so as to be rotatable via heated roll bearings 78 arranged on both sides of the roll portion 74. The roll portion 74 includes a core 80 made of, for example, iron or aluminum, and a release layer 82 coated or applied to the core 80. The core 80 has an outer shape of, for example, 25 mm and a thickness of, for example, 0.1 to 1 mm. 0.5 mm. The release layer 82 is made of a material having insulating properties and excellent release properties, for example, perfluoroalkoxy (PFA), and has a thickness of, for example, 30 to 100 μm.
A gear 84 is fixed to one end of the roll part 74, and the roll part 74 receives a driving force via the gear 84. Further, a plurality of (for example, five) peeling claws 86 described below are in contact with the roll portion 74. The heater 76 includes, for example, two lamps, and both ends of the lamp are fixed to the first housing 66.
The pressure roll 88 has a rotating shaft 90 made of stainless steel, iron, or the like, a heat-resistant elastic layer 92 that rotates about the rotating shaft 90, and a coating layer 94 that covers the periphery of the heat-resistant elastic layer 92. . The heat-resistant elastic layer 92 is made of a silicon sponge (Asker C hardness: 40 degrees) having a thickness of, for example, 6 to 8 mm. The covering layer 94 is made of a conductive material, for example, conductive PFA. 100 μm. The pressure roll 88 is pressed against the roll portion 74 of the heating roll 72 so as to press the heating roll 72 by a pressure unit described later, and a nip 96 is formed between the pressure roll 88 and the heating roll 72.
An inlet chute 98 made of a conductive material such as stainless steel is fixed to the second housing 68 so as to be arranged on the upstream side of the nip 96. Outlet chutes 100, 100 are provided in the first housing 66 and the second housing 68, respectively, on the downstream side of the nip 96. The outlet chute 100 of the first housing 66 is formed integrally with the first housing 66, and the outlet chute 100 of the second housing 68 is provided rotatably with respect to the second housing 68, and is formed by a recording medium. The outlet chute 100 of the second housing 68 is opened to guide and pass the recording medium.
The pressurizing elastic body 102 is made of, for example, a coil spring, and is elastically interposed between the first housing 66 and the rotary cam 104. The rotating cam 104 is rotatably supported by the pressing arm 106 near one end of the pressing arm 106. The rotating cam 104 is provided with a lever 108 projecting in the radial direction of the rotating cam 104. The rotation axis 90 of the pressure roll 88 is rotatably supported at a substantially central portion of the pressure arm 106. Further, the vicinity of the other end of the pressure arm 106 is rotatably supported by the second housing 68 via an arm fulcrum 110. The arm fulcrum 110 is located near the housing fulcrum 70 and on the anti-elastic body side with respect to the housing fulcrum 70.
When assembling the fixing unit 36, the rotating cam 104 is initially at the first position shown by the solid line in FIG. 5, and the pressing elastic body 102 is almost extended to engage the pressing elastic body 102. It is not necessary and can be easily mounted. Next, the rotating cam 104 is rotated downward by holding the lever 108, and the rotating cam 104 is moved to the second position shown by the two-dot chain line in FIG. As a result, the pressurizing elastic body 102 is pulled and extended, and the pressurizing roll 88 moves toward the heating roll 72 via the pressurizing arm 106 to apply the heating roll 72 with a predetermined force so as to have a predetermined nip width. Become pressure. Here, since the arm fulcrum 110 of the pressure arm 106 is on the anti-elastic body side with respect to the housing fulcrum 70, the second housing 68 receives a reaction force toward the first housing 66, and this reaction force The second housing 68 is pressed against the first housing 66, and the first housing 66 and the second housing 68 are combined.
FIGS. 6 to 11 show the above-described peeling claw 86 and the peripheral portion of the peeling claw 86. FIG. The peeling claw 86 has a peeling claw main body 112 whose tip is formed at an acute angle, and a support shaft 114 formed to protrude to both sides of the peeling claw main body 112 near the rear end of the peeling claw main body 112. The support shaft 114 is inserted into a support groove 116 formed in the first housing 66, and the peeling claw 86 is rotatably supported by the first housing 66. Further, between the peeling claw body 112 and the first housing 66, a peeling claw elastic body 118 made of, for example, a coil spring is mounted, and the tip of the peeling claw body 112 is attached to the roll portion 74 of the heating roll 72. It comes into pressure contact.
The support shaft 114 has a notch 120 formed by cutting a cylindrical portion on both sides in parallel planes. On the other hand, the support groove 116 has an insertion section 122 on the distal end side and a rotation support section 124 formed on the inner side of the insertion section 122. The insertion portion 122 is formed of a parallel surface substantially equal to the diametrical width of the notch 120 of the support shaft 112 of the peeling claw 86. Further, the cross section of the rotation support portion 124 is formed as a partial circle. Accordingly, as shown in FIG. 7, the notch 120 of the support shaft 114 is aligned with the insertion portion 122 of the support groove 116, and the peeling claw 86 is moved in parallel, so that the support shaft 114 is supported as shown in FIG. The rotation support portion 124 of the groove 116 is inserted, and the support shaft 114 is rotatably supported by the rotation support portion 124. Therefore, at positions other than the position where the cutout portion 120 of the support shaft 114 and the insertion portion 122 are aligned, the peeling claw 86 is fixed to the first housing 66 so as to allow only rotation, and the peeling claw 86 falls off the first housing 66. Has been prevented. That is, in the present embodiment, the support shaft 114 and the support groove 116 constitute a drop-off preventing means for preventing the peeling claw 86 from dropping from the first housing 66.
The support shaft 114 is provided with a stopper 126 protruding in the radial direction of the support shaft 114. As shown in FIG. 8, the stopper portion 126 regulates clockwise rotation of the peeling claw 86 at a position where the stopper portion 126 contacts the lower surface of the support groove 116 and the peeling claw 86 faces downward. As shown in FIG. 11, the stopper 126 abuts on the upper surface of the support groove 114 and regulates the rotation of the peeling claw 86 in the counterclockwise direction at a position where the peeling claw 86 faces forward. That is, the rotation range of the peeling claw 86 is regulated between the position where the peeling claw 86 faces downward and the position where it faces forward, and the peeling claw 86 can be inserted into the first housing 66 within this rotation range. It has become.
As described above, since the peeling claw 86 is supported by the first housing 66 in a state of being overlapped with the heating roll 72, it becomes an obstacle when the roll portion 74 of the heating roll 72 is inserted. Therefore, a retracting means for retracting the peeling claw 86 from the insertion portion of the roll portion 74 is provided. In this embodiment, as shown in FIG. 9, the separation claw 86 is retracted by the retracting jig 128. That is, the evacuation jig 128 is made of a bar extending over both side surfaces of the first housing 66, and when the peeling claw 86 is attached, both sides of the evacuation jig 128 are attached to the first housing 66. For example, it is supported by a jig support 130 formed on the side surface. Then, the lower surface of the peeling claw main body 112 abuts on the evacuation jig 128, and the peeling claw 86 is retracted from the range where the roll portion 74 of the heating roll 72 is inserted, so that the heating roll 72 is easily moved to the first housing 66. It can be attached to. After the mounting of the roll portion 74 of the heating roll 72, the evacuation jig 128 is removed, and the peeling claw 86 is brought into contact with the roll portion 74. Therefore, the peeling claw 86 cannot be brought into contact with the roll portion 74 unless the evacuation jig 128 is removed, so that it is possible to prevent the peeling claw 86 from being left at the retracted position.
In this embodiment, the evacuation jig 128 is used as evacuation means for the peeling claw 86, but the invention is not limited to this, and as another embodiment, the evacuation means is provided in the first housing 66. For example, latch means for temporarily holding the peeling claw 86 at the retracted position may be provided in the first housing 66.
Next, the operation of the above embodiment will be described.
The image carrier 44 is uniformly charged by the charging device 56, and the charged image carrier 44 is irradiated with light emitted from the optical writing device 58 based on the image signal to form a latent image. Light from the optical writing device 58 passes through the process cartridge 64. The latent image on the image carrier 44 formed by the optical writing device 58 is visualized by a developing device 60 with a developer.
On the other hand, one of the paper feeding units 18 is selected by a size signal or the like, and the recording medium stored in one of the paper feeding cassettes 20 is sent out by the pickup roll 24, temporarily stopped by the registration roll 38, and the timing is adjusted. Thus, it is guided between the transfer device 42 and the image carrier 44.
When the recording medium is guided between the transfer device 42 and the image carrier 44 in this manner, the developer on the image carrier 44 is transferred to the recording medium by the transfer device 42. The recording medium to which the developer has been transferred passes through the fixing unit 36, the developer on the recording medium is fixed to the recording medium, and is discharged to the discharge unit 16.
Next, a method of assembling the fixing unit 36 will be described.
First, as shown in FIG. 7, the notch 120 of the support shaft 114 is aligned with the insertion portion 122 of the support groove 116,
Insert the peeling claw 86 in the direction indicated by the arrow. As a result, as shown in FIG. 8, the support shaft 114 is fitted into the rotation support portion 124 of the support groove 116, and the peeling claw 86 is rotatably supported by the first housing 66. Next, as shown in FIG. 11, the peeling claw 86 is rotated upward once, the evacuation jig 128 is supported by the jig support 130, and the peeling claw 86 is brought into contact with the evacuation jig 128. The peeling claw 86 is retracted. Next, as shown in FIG. 9, the roll portion 74 of the heating roll 72 is stored in the first housing 66. After attaching the roll portion 74 of the heating roll 72 to the first housing 66, the evacuation jig 128 is removed, and the peeling claw 86 is returned so as to contact the roll portion 74 of the heating roll 72 as shown in FIG. .
Thereafter, the first housing 66 on which the heating roll 72 is mounted and the second housing 68 on which the pressure roll 88 and the inlet chute 98 are mounted are assembled by the elastic body 102 for pressurization.
In the above embodiment, the peeling claw 86 is provided on the heating roll 72. However, the present invention is not limited to this, and may be provided on the pressure roll 88 as another embodiment.
[0037]
As described above, according to the present invention, the peeling claw that comes into contact with the fixing roll is supported by the housing in which the fixing roll is stored, and at the same time, the peeling claw is prevented from falling off the housing. Since the means is provided, the number of parts can be reduced, and work such as a jam can be easily performed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating an image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a perspective view of a fixing unit according to the embodiment of the present invention.
FIG. 3 is a perspective view showing the fixing unit according to the embodiment of the present invention, and excluding a first housing.
FIG. 4 is a sectional view of a fixing unit according to the embodiment of the present invention.
FIG. 5 is a side view of the fixing unit according to the embodiment of the present invention.
FIG. 6 is a perspective view showing a peeling claw used in a fixing unit and a peripheral portion thereof in the embodiment of the present invention.
FIG. 7 is a side view showing a peeling claw used in the fixing unit according to the embodiment of the present invention and a peripheral portion thereof, and showing a state before inserting the peeling claw.
FIG. 8 is a side view illustrating a peeling claw used in the fixing unit according to the embodiment of the present invention and a peripheral portion thereof, showing a state after the peeling claw is inserted.
FIG. 9 is a side view illustrating a peeling claw used in the fixing unit according to the exemplary embodiment of the present invention and a peripheral portion thereof, illustrating a state in which a heating roll is stored.
FIG. 10 is a side view showing a peeling claw used in the fixing unit and a peripheral portion thereof in the embodiment of the present invention, and showing a state after storage of a heating roll.
FIG. 11 is a side view showing a peeling claw used for the fixing unit and a peripheral portion thereof used in the embodiment of the present invention, and showing a state where the peeling claw is rotated upward.
[Explanation of symbols]
REFERENCE SIGNS LIST 10 image forming apparatus 12 image forming apparatus main body 14 image forming means 36 fixing unit 64 process cartridge 66 first housing 68 second housing 70 housing fulcrum 72 heating roll 86 peeling claw 88 pressure roll 98 inlet chute 114 support shaft 116 support Groove 120 Notch 122 Insertion part 124 Rotation support part 126 Stopper part 128 Evacuation jig 130 Jig support part

Claims (6)

A fixing roll, a peeling claw that comes into contact with the fixing roll, and the fixing roll are housed, the peeling claw is rotatably supported, one surface facing the fixing roll is opened, and the peeling claw is supported. A fixing unit, comprising: a housing whose other surface is closed; and a stopper for preventing the peeling claw from falling off the housing. The falling-off preventing means is formed in the housing so as to have a notch portion formed by cutting out a peripheral surface of the support shaft of the peeling claw, and an insertion portion having substantially the same width as the diameter of the support shaft in the notch portion. 2. The fixing unit according to claim 1, wherein the fixing unit comprises a support groove. The fixing unit according to claim 1, further comprising a retracting unit that retracts the peeling claw so that the fixing roll can be inserted into the housing. The fixing unit according to claim 1, wherein a jig support portion that supports an evacuation jig that retreats the peeling claw so that the fixing roll can be inserted into the housing is provided in the housing. . A retracting step of retracting the peeling nail rotatably supported by the housing, a storing step of storing the fixing roll in the housing after retracting the peeling nail, A method of assembling the fixing unit, comprising: 6. The fixing unit assembling method according to claim 5, wherein in the evacuation step, an evacuation jig for holding the peeling claw at an evacuation position is used.

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