JP2598270B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a copier, a printer, a facsimile, etc.
The present invention relates to an image forming apparatus provided with a roller fixing device of a pressure roller type or a heat roller type.

[Conventional technology]

2. Description of the Related Art In recent years, in image forming apparatuses such as copiers, printers, and facsimile machines, regular replacement parts are becoming cartridges. The purpose is to make replacement parts into cartridges so that ordinary users can easily replace them. Thus, there is a need to reduce maintenance service costs. Conventionally, as a cartridge of a replacement part in an image forming apparatus, for example, as disclosed in Japanese Patent Application No. 59-274297, a regular replacement part, particularly including an image forming drum, disposed in the vicinity thereof is integrated. Many cartridges have been proposed which can be replaced by ordinary users.

[Problems to be solved by the invention]

However, as described above, various replacement parts in the image forming apparatus are made into cartridges. However, when a heat roller fixing device is employed, for example, a heat roller, a cleaner, a driven roller, and the like are periodically replaced. Although there are many members to be used, there has not yet been proposed a cartridge which can be exchanged by a user as a cartridge, and the fixing device is fixed to the apparatus main body by screwing or the like.
Further, the electrical connection to the heat roller fixing device is made by connecting a connector extended outside the fixing device to a wiring portion in the apparatus main body. In order to replace the fixing device, a maintenance technician uses a tool such as a screwdriver to perform a more difficult positioning operation or the like to perform the replacement operation.

Therefore, even if the replacement parts around the drum part are made into cartridges and configured to be replaceable by ordinary users, if the fixing part is not made into a cartridge, maintenance service for the regular replacement parts of the fixing part is required, and the cartridge of the periodic replacement parts is required. Since the effect of image formation is reduced by half, the demand for user replacement of the fixing device is increasing. However, as described above, the replacement of the fixing device has a problem that it cannot be replaced by a general user because it is necessary to use a tool and perform difficult positioning and to connect a complicated connector.

SUMMARY An advantage of some aspects of the invention is to provide an image forming apparatus including a roller fixing device that is made into a cartridge and can be easily attached to and detached from the apparatus main body. Aim.

[Means and actions for solving the problems]

In order to solve the above-mentioned problems, the present invention provides a roller fixing device that fixes a toner image on a sheet on which a toner image has been transferred by nipping and conveying the sheet with a pair of rollers, and fixing the roller fixing device. Positioning means fixed to the apparatus main body, which abuts on the roller fixing device when mounting so as to be held by the apparatus main body by its own weight, and is fixed to the apparatus main body. In the image forming apparatus, in a state in which the driving gear provided in the apparatus main body meshes with a driven gear provided in the roller fixing device in a mounted state to transmit a driving force to the roller, The driving force of the driving gear with respect to the driven gear in the meshing device has a downward component force, and presses the roller fixing device to the positioning unit via the driven gear, thereby fixing the roller. The attachment to the vessel of the apparatus main body and constitutes to stabilize.

With such a configuration, the roller fixing device is positioned by the positioning means by dropping the roller fixing device into the mounting position of the apparatus main body, and is held by the apparatus main body by its own weight and provided on the apparatus main body. When a driving force having a downward component force is transmitted from the driving gear to the driven gear, the roller fixing device held in the apparatus main body is further pressed by the positioning device by the own weight of the fixing device itself. Thus, the roller fixing device is more stably held by the apparatus main body, and a mounting and holding member for holding the roller fixing device from above is unnecessary.

〔Example〕

Hereinafter, embodiments will be described. FIG. 1 is a schematic cross-sectional view showing an overall configuration of an embodiment of an image forming apparatus according to the present invention. This embodiment shows a printer using an ion flow type recording head. In FIG. 1, reference numeral 2 denotes a dielectric drum, and a recording head 3 for emitting an ion stream modulated in accordance with an image signal to be recorded on the dielectric drum 1 in a dot form to form an electrostatic image. Reference numeral 4 denotes a developing device for developing the electrostatic image on the dielectric drum 1 with toner, and 4 denotes a transfer roller for transferring the toner image on the drum 1 to paper. Reference numeral 5 denotes a cleaning blade for removing toner remaining on the dielectric drum 1 after transfer, 6 a paper feed tray disposed on the side of the apparatus main body 7, and 8 and 9 separating and feeding the paper 10 from the tray 6. Paper feed rollers and retard, paper transport guides 11, 12, 13, 14; paper transport rollers 15, 16; paper transport guides 17, 18; transfer toner image 19 by heat and pressure A fixing cartridge for fixing, a reversing discharge unit 20 for reversing and discharging the sheet on which the toner image is fixed, and a stacker 21 for storing the discharged sheet. And the transfer guide after transfer
The fixing cartridges 17, 18, the fixing cartridge 19, and the reversing discharge unit 20 are supported by a unit frame 22 that can be pulled out in the paper discharging direction from the apparatus main body 7, and can be integrally pulled out.

Next, the configuration of the unit frame 22 will be described with reference to FIGS. As shown in FIG. 2, a unit support member 24 is fixed to a base plate 23 of the apparatus main body 7.
The fixed side of the slider 25 is fixed to the unit support member 24. A unit base 26, which is one of the constituent members of the unit frame 22, is fixed to the movable side of the slider 25. As shown in FIG.
The unit frame 22 can be pulled out in the sheet discharging direction as described above by releasing a lock mechanism described later.

As shown in FIG. 4, the unit frame 22 includes the unit base 26, the front side plate 27, and the rear side plate 28, and is equipped with a lock mechanism described later. Next, the lock mechanism will be described. An approximately L-shaped release lever 30 is fixed to a lever shaft 29 rotatably supported by the front side plate 27 and the rear side plate 28 between the front side plate 27 and the rear side plate 28 and near the front side plate 27. A pivot 31 is fixed to one end of the release lever 30, and a roller 32 is rotatably supported by the pivot 31. The other end of the release lever 30 penetrates a hole provided in the unit base 26 (not shown) and protrudes to the outside of the unit frame 22, and is located at a position where the operator can operate.

One end of the lever shaft 29 is provided on the rear plate 28 side.
And a cam member 33 that rotatably supports the roller 32 like the release lever 30 is disposed at the other end. The lever shaft 29 is urged by an urging means (not shown) so as to receive a moment in the direction opposite to the arrow A, but the release lever 30 comes into contact with the end of the through hole of the release lever 30 of the unit base 26. A predetermined position is maintained. On the outer peripheral surface of the roller 32 of the release lever 30, a front nip release member is provided.
A rear nip release member 35 is disposed on the outer peripheral surface of the roller 32 of the cam member 33 so as to abut a part thereof. Both nip releasing members 34 and 35 are swingably supported at both ends by nip releasing shafts 36 fixed to the front side plate 27 and the rear side plate 28, respectively, and are in a direction of contacting the roller 32 by urging means (not shown) (C (In the opposite direction to the direction). The nip releasing members 34, 35 have the same U-shaped cutouts 34a, 35a at the upper part, and also have the same bent bent lock parts 34b, 35b at the lower part.

In the vicinity of the lock portions 34b, 35b of the nip release members 34, 35, a front hook member 37 and a rear hook member 38 are provided, respectively.
Are fixedly arranged on the hook shaft 39, and the hook shaft
Numeral 39 is rotatably supported at both ends by the front plate 27 and the rear plate 28 and is urged by an urging means (not shown) to receive a moment in the direction of arrow B. The hook members 37, 38 have notches 37a, 38a into which the lock portions 34b, 35b fit when the nip release members 34, 35 rotate around the nip release shaft 36 in the direction of arrow C. Further, as shown in FIG. 5, the rear hook member 38 penetrates through a manual nip portion 38b and a hole provided in the unit base 26 to form the unit base unit.
An arm portion 38c extending to the back side of the unit 26 and a stopper portion 38d abutting on the back side of the unit base 26 are formed.

One end of a link A40 is rotatably supported by the front nip release member 34, and the other end of the link A40 is a link B.
It is rotatably supported at the center of 41. And link
One end of B41 is supported by the lever shaft 29, and the other end rotatably supports the link C42. The link C42 has a notch 42a, and one end of a substantially L-shaped lock lever 44 rotatably supported by a pivot B43 fixed to the unit base 26 is engaged with the notch 42a. I have. The other end of the lock lever 44 has a notch 44a that engages with a lock pin 45 fixed to the base plate 23 of the apparatus main body 7, and a moment in a direction in which the lock pin 45 is brought into contact with the lock pin 45 by urging means (not shown). It is configured to receive.

FIG. 5 shows the lock set member 46 and the rear hook member 38. One end of the lock set member 46 is swingably supported by the unit support member 24, and the other end is an arm portion 38c of the rear hook member 38 when the unit frame 22 is pulled out.
A bending member 46a is formed so as to engage with
The stopper 46b is configured to contact the unit support member 24 by receiving a moment in the direction of arrow D by a biasing means (not shown).

Next, the paper guide mechanism after the transfer will be described. Sixth
The figure shows a cross-sectional view of the paper guide after transfer. Top paper guide 17
Is arranged such that the paper guide portion is formed in a convex shape, and the convex portion protrudes below a virtual line 1 connecting the transfer portion and the fixing portion. An elastic member 47 is provided on the transfer section side of the upper paper guide 17.
The peeling claw 48 is supported via the elastic member 47 and is pressed against the outer periphery of the dielectric drum 1 by the elastic force of the elastic member 47. The fixing section side of the upper paper guide 17 extends to near the fixing section of the fixing cartridge 19 held in the unit frame 22, and both ends in the direction perpendicular to the transport direction are swingably supported by the front plate 27 and the rear plate 28. Both ends on the transfer section side are supported by a link mechanism (not shown). Further, the protruding portion of the upper paper guide 17 supports a star wheel 49 so as to be rotatable and a part of the outer peripheral portion is exposed below the protruding portion. The lower paper guide 18 is fixed to the upper paper guide 17, and is formed in a concave shape so that the paper guide surface is kept at a predetermined distance from the upper paper guide 17. Sheet guide 18
A lower peeling claw 51 is also supported on the transfer portion side via an elastic member 50, and is configured to press against the outer peripheral surface of the transfer roller 4 by the elastic force of the elastic member 50.

Next, the configuration of the fixing cartridge 19 will be described with reference to FIGS. FIG. 7 is a sectional view of the fixing cartridge 19. The fixing cartridge 19 is a fixing plate front side plate 52.
And a fixing plate rear side plate 53 (see FIG. 8). A first tie plate 54, a second tie plate 55, and a third tie plate 56 are fixed between the both side plates 52 and 53, respectively. And handle parts 52a, 53a bent outward are formed at the upper part of both side plates 52, 53, and at the lower part,
U-shaped notches 52b, 53b are formed to engage with reference pins 81, 82 projecting from the unit frame 22. Note that the reference pin 81 and the notch 52b are provided on the front side plate 52 side, and only the rear side plate 53 side is shown in FIGS. 7 and 10, so the corresponding portions are indicated by parentheses. Is shown. A thermistor 58 that is in contact with the outer peripheral surface of the heat roller 57 is fixed to the first tie plate 54 via a leaf spring 59.
Further, when the fixing cartridge 19 is mounted in the unit frame 22, the fixing cartridge 19 engages with the U-shaped notch 60 a of the tie plate 60 of the unit frame 22, and is perpendicular to the transport direction of the fixing cartridge 19 with respect to the unit frame 22. A thrust reference pin 61 for determining the position in the direction is fixed (see FIGS. 10 and 11).

The heat roller 57 is formed of a pipe having both ends narrowed to a small diameter, is rotatably supported by the fixing cartridge front plate 52 and the fixing cartridge rear plate 53 via a bearing 62, and extends outside the fixing cartridge rear plate 53. A heat roller driving gear 63 is fixed to the sleeve portion as shown in FIG. Numeral 64 denotes a halogen lamp, which is disposed so as to penetrate the inside of the heat roller 57, and both ends of which are supported by support members 65 fixed to the fixing cartridge front side plate 52 and the fixing cartridge rear side plate 53, respectively, as shown in FIG. Supported. A driven roller 66 has a shaft covered with silicone rubber, and the shaft is rotatably supported by a driven roller support member 67 via a bearing (not shown).

The driven roller support member 67 is swingably supported at one end by a support shaft 68 fixed to the fixing cartridge rear plate 53, and the other end is caught by a nip spring 69. Below the driven roller support member 67, a nip release support shaft 70 is fixed to the fixing cartridge front plate 52 side, and on the opposite side to which the nip release support shaft 70 is fixed, an initial release link support shaft 71 is provided. Has been fixed. An initial release link 72 has an elongated hole 72a formed at one end. The elongated hole 72a is supported by an initial release link support shaft 71, and the other end is an initial release lever.
It is swingably supported by a support shaft 74 fixed to 73. The initial release lever 73 is swingably supported by a support shaft 75 fixed to the rear side plate 53 of the fixing cartridge.

FIG. 7 shows that the acting force of the nip spring 69 is
The initial release lever 73 is moved to the arrow E
In the direction of rotation, and the acting force is supported by the one end face 73a of the initial release lever 73 abutting against the stopper 53c bent inside the fixing cartridge rear side plate 53. At this time, the driven roller support member 67 is pulled down by the initial release link 72,
The nip between the heat roller 57 and the driven roller 66 has been released. The mechanism for supporting the driven roller 66 and the mechanism for releasing the initial nip have been described on the side of the fixing cartridge rear plate 53 shown in FIG. 7, but the driven roller supporting mechanism and the initial nip having the same configuration are also provided on the fixing cartridge front plate 52 side. A release release mechanism is provided.

As shown in FIG. 8, the third tie plate 56 has a lower central portion cut out largely, and a spring support member 76 is fixed to both ends thereof so as to hook one end of the nip spring 69. A blade holder 78 holding a blade 77 for removing paper dust and offset toner on the outer peripheral surface of the heat roller 57 is held. As shown in FIG. 9, the blade 77 is integrally formed with a fluoro rubber portion 77a in contact with the heat roller 57 and a held portion 77b of phosphor bronze, and the held portion 77b is formed between the blade holder 79 and the holding portion 78b of the blade holder 78. It is held so that it is sandwiched between. The blade holder 78 includes the holding portion 78b, the handle portion 78a, and two contact portions 78c at both ends, and a part 78d of the contact portion 78c contacts the upper end surface of the hole provided in the third tie plate 56. It has become. The blade holder 78 is configured to be held by a reaction force received when the blade 77 is pressed against the heat roller 57.

Numeral 80 denotes an inlet chute, both ends of which are fixed to the front and rear plates 52, 53 of the fixing cartridge, and are arranged upward from the upstream in the transport direction to the downstream, and the extension thereof goes to the nip point between the heat roller 57 and the driven roller 66. It has become.

Reference numeral 111 denotes a cartridge connector fixed to the second tie plate 55, which electrically connects to the halogen lamp 64 and the thermistor 58 in the fixing cartridge 19. And the cartridge connector 111 is
Unit base can be installed and removed with the fixing cartridge 19
The unit connector 113 is configured to come into contact with and separate from the unit connector 113 supported by the connector holder 112 fixed to 26. In this way, the connectors 111 and 113 are
Since it is fixed to the tie plate 55 or the connector holder 112 disposed below the driven roller 7 and the driven roller 66, it is not affected by heat, and can be safely connected without deformation.

Next, a holding mechanism of the fixing cartridge 19 in the unit frame 22 and members related to mounting the fixing cartridge 19 will be described. A space for mounting the fixing cartridge 19 is formed in the unit frame 22.
At the top, an opening is provided to make the fixing cartridge 19 detachable. When the unit frame 22 is set in the apparatus main body 7, the opening is hidden below the upper convex portion 7a of the apparatus main body 7 as shown in FIG.
The opening appears only when you pull out the fixing cartridge 19
Can be attached and detached.

FIG. 10 shows a cross section of a main part in a state where the fixing cartridge 19 is mounted in the unit frame 22. When the fixing cartridge 19 is mounted by being lowered from the opening, the thrust reference pin 61 of the fixing cartridge 19 is set to the unit frame 22 as shown in FIG. The tie plate 60 is positioned by engaging with the notch 60a formed in the tie plate 60, and the paper transport direction and the vertical direction are aligned with reference pins 81, 82 fixed to the front side plate 27 and the rear side plate 28 of the unit frame 22. The position of the cartridge is determined by the engagement of the cartridge side plates 52 and 53 with the notches 52b and 53b and the contact plates 83 and 84 formed on the unit frame 22. Note that the contact plate 83 is provided on the front plate 27 of the unit frame 22, and only the rear plate 28 is shown in FIG. 10, so the corresponding parts are shown in parentheses.

The members are arranged such that the heat roller 57 is parallel to the dielectric drum 1 of the apparatus main body 7 when mounted in such a manner. At the same time, the cartridge connector 111 is connected to the unit connector 113. Reference numeral 85 denotes a push-up member provided on the unit base 26, which comes into contact with the initial release lever 73 when it is lowered from the opening of the unit frame 22 to mount the fixing cartridge 19,
It is configured to push this up.

Next, the configuration of each unit after fixing will be described. Reference numeral 86 denotes a heat roller peeling claw, which is swingably supported by the claw shaft 87 and is urged by an urging means (not shown) so that the tip of the heat roller 57 comes into contact with the heat roller 57. As shown in FIG. 12, the claw shaft 87 has both ends supported by elongated holes formed at both ends bent 88a of the upper claw case 88, and has a leaf spring 88b fixed to the bent portion 88a as shown in FIG. Urged upward.
At the position corresponding to the heat roller peeling claw 86 of the upper claw case 88,
A bent claw storage portion 88c is formed inside the case. Reference numeral 89 denotes a lower nail case, which is fixed integrally with the upper nail case 88 to form a box-shaped nail cassette. A slit 89a is formed in a portion of the lower nail case 89 corresponding to the heat roller peeling claw 86 so as not to hinder the rotation of the heat roller peeling claw 86. The lower surface of the lower claw case 89 also serves as a paper guide. Before mounting, the heat roller peeling claw 86
As shown in FIG. 13, the stop portion 86a contacts the storage portion 88c of the upper claw case 88 and is stored in the claw cassette.

In order to mount the claw cassette, arrows G are attached along supporting members 92 and 93 fixed to the inversion front side plate 90 and the inversion rear side plate 91 described later.
By pushing in the direction, the claw shaft 87 is once pushed down against the urging force of the leaf spring 88b by the projections 90b, 91b of the side plates 90, 91, and then fitted and supported in the U-shaped notches 90a, 91a. It is attached. At the time of this installation,
Is temporarily pushed down, the stop portion 86a of the heat roller peeling claw 86 is disengaged from the storage portion 88c of the upper claw case 88 at that time, and the heat roller peeling claw 86 is rotated by the urging force of the urging means (not shown). Move, the tip protrudes from the claw cassette,
It becomes available.

Referring again to FIG. 10, another configuration after fixing will be described. 94 is a lower paper guide, both ends of which are reversed both sides 90, 91
(Only 91 is shown in FIG. 10) so that the downstream side in the transport direction is higher. 95 is a first reversing roller, 96 is a second reversing roller, and 97 is a third reversing roller.
The first and second reversing rollers 9 are rotatably supported by 90 and 91.
5, 96 and the second and third reversing rollers 96, 97 are in contact with each other, are respectively connected to a drive system (not shown), and are configured to rotate in the direction of the arrow.

In this configuration example, the first and second reversing rollers 95, 9
6 is arranged so that the line connecting the nip point and the nip point of the heat roller 57 and the driven roller 66 is inclined by 16 degrees with respect to the horizontal line, and the line connecting the centers of both reversing rollers 95 and 96 is It is arranged so as to be inclined 20 degrees with respect to the vertical line.

Reference numeral 98 denotes a paper reversing guide, which is a paper entry plate made of a conductive plate.
98a and a wire paper receiving portion 98b made of a U-shaped conductive wire attached to the bent end portion of the paper entry plate 98a, and the paper inversion guide portion 98 is inclined at 25 degrees with respect to the vertical line. It is arranged. 99, 100 are static elimination brushes, and the static elimination brush 99 is supported and attached to the reversing side plates 90, 91 in the vicinity of the intersection of the sheet conveying direction by the first and second reversing rollers 95, 96 and the sheet reversing guide 98. In addition, the charge removing brush 100 is supported by a bent portion of the leading end of the paper entry plate 98a of the paper reversing guide 98.

A paper discharge guide 101 is fixed to the front plate 27 and the rear plate 28 of the unit frame 22, and guides the reversed paper conveyed by the second and third reversing rollers 96 and 97 to the paper discharge rollers 102 and 103. It is supposed to. Discharge roller 10
2 and 103 are both the front plate 27 and the rear plate 28 of the unit frame 22.
The driving force is transmitted to the upper discharge roller 102 from a driving system (not shown). The reversing both side plates 90 and 91 are integrated by a tie plate (not shown), and are swingably supported by the upper discharge roller 102 between the front side plate 27 and the rear side plate 28.

Next, transmission of the driving force to the fixing cartridge 19 will be described. As shown in FIG. 14, one end of a gear plate 104 is swingably supported by the rear plate 28 of the unit frame 22, and is biased in the direction of arrow H by a biasing means (not shown). Part of the fixed stopper pin 105 abuts and is held at that position. On the other hand, an output gear 106 is rotatably supported at the other end, and meshes with the heat roller drive gear 63 of the fixing cartridge 19. The output gear 106 is connected to a drive system (not shown) so as to receive a driving force from the apparatus main body. When the driving force is transmitted, but the F direction of the force to the fixing cartridge 19 via the heat roller drive gear 63 acts, a component force F ₁ of the sheet conveyance direction prior to the unit frame 22, the rear plate
27 and 28 is received in the contact plate 83 and 84 fixed (FIG. 10), the downwardly other component force F ₂ as is to be perceived in the reference pins 81 and 82 which are also fixed to the side plates 27 and 28 It has become. That is, the fixing cartridge 19 is more stably held in the unit frame 22 by transmitting the driving force from the apparatus main body, and therefore, a member for holding the fixing cartridge 19 by pressing it from above is unnecessary.

Next, the operation of the image forming apparatus thus configured will be described together with the movement of the sheet. The paper 10 stacked on the paper feed tray 6 is separated and transported one by one by a paper feed roller 8 and a retard 9, and is transported by a paper transport guide 11, 12, 13, 14.
To the nip between the dielectric drum 1 and the transfer roller 4. Here, the toner image on the dielectric drum 1 is pressure-transferred onto the paper 10, and the leading end of the paper 10 advances so as to wind around the dielectric drum 1 and is peeled off by the upper peeling claw 48, as shown by a two-dot chain line in FIG. Until the point K, only the leading end of the sheet advances while being guided by the upper sheet guide 17. When the leading end passes the point K, the sheet loses its weight due to its own weight and is guided by the lower sheet guide 18. While the stiffness of the paper is stronger than its own weight, only the leading edge of the paper is guided by the upper paper guide 17 facing downward, so that there is nothing to touch the unfixed image surface, so that the image is disturbed or stained. Is conveyed to the fixing cartridge 19 without causing the image formation.

The sheet 10 conveyed to the fixing cartridge 19 is guided by the inlet chute 80, is sandwiched between the heat roller 57 and the driven roller 66, and the toner is melted and fixed by heat and pressure. After the fixing, the paper advances so as to wind around the heat roller 57, and is separated by the heat roller separation claw 86 and advances. At this time, the paper
As shown by the two-dot chain line in FIG. 10, the leading end curls upward and is guided smoothly so that the leading end becomes higher toward the downstream in the transport direction. If this is configured to be guided downward as after the transfer by the transfer roller 4, the paper will bend against the waist of the paper, and as shown in FIG. A waving phenomenon occurs at 10a.

Further, the sheet advances, is conveyed by the first reversing roller 95 and the second reversing roller 96, and collides with the paper entry plate 98a of the sheet reversing guide section 98. At this time, the entry angle of the sheet is determined by the angle of the sheet entry plate 98a and the angle of a line connecting the centers of the first reversing roller 95 and the second reversing roller 96. In this embodiment, as shown in FIG. Degrees. When the plunge angle becomes large, not only is the leading end of the sheet damaged by the collision, but also, as shown in FIG. 16 (A), the sheet is conveyed by the sheet 10b which has been previously conveyed to the sheet reversing guide 98 and turned over. There is a problem that the leading edge of the sheet 10c is pulled in and discharged without being turned over. In order to reduce the rush angle,
As shown in FIG. 9B, when the angle formed by the line connecting the centers of the first reversing roller 95 and the second reversing roller 96 is increased, the rear end of the carry-in paper 10c slips on the second reversing roller 96, There is a problem that the sheet is not transferred to the third reversing roller 97 side. On the other hand, if the angle of the sheet reversing guide section 98 is increased to reduce the plunging angle, the sheet reversing guide section 98 will be in the form of lying down sideways, which causes a problem that the installation space of the apparatus is increased. It is desirable to keep the entry angle at 30 to 60 degrees.

By the way, the sheet that has reached the sheet entry plate 98a of the sheet reversing guide section 98 rises along the sheet entry plate 98a by the conveying force of the first and second reversing rollers 95, 96 and is conveyed to the wire sheet receiving section 98b. . When the trailing edge of the paper leaves the nip point between the first and second reversing rollers 95 and 96, the trailing edge of the paper is transferred to the third reversing roller 97 by the second reversing roller 96. Next, the paper is conveyed from the rear end side by the second and third reversing rollers 96 and 97, and is discharged and stored in the discharge stacker 21 by the discharge rollers 102 and 103 via the discharge guide 101.

Also, in this paper reversal transport process, the first and second
The paper conveyed by the reversing rollers 95 and 96 rises along the paper plunging plate 98a while being neutralized by the neutralizing brush 99 near the position where the paper reversing guide unit 98 collides with the paper plunging plate 98a. The charge generated by the frictional contact with the rush plate 98a due to the rising operation or the frictional contact with the previously conveyed and inverted sheet is removed by the neutralization brush 100 disposed at the leading end of the paper rush plate 98a. Is done. In addition, since the charge generated on the sheet that reverses and descends along the paper entry plate 98a is discharged by both the discharge brushes 99 and 100,
The sheet is effectively prevented from sticking to the paper entry plate 98a due to charging.

Further, the discharging brush 99 is connected to the first and second reversing rollers 95 and 96.
Paper inversion guide section 9 by second and third reversing rollers 96 and 97 so as to form an acute angle with respect to the paper transport direction
By arranging the paper at an acute angle with respect to the paper transport direction from 8, the static elimination brush 99
And smooth paper transport.
Further, by disposing the neutralization brush 99 in this manner, the neutralization brush 99 also functions as a paper conveyance guide, reliably transports the paper to the paper reversing guide unit 98, and furthermore, the second and third papers to be reversed. Carrying in the direction of the reversing rollers 96 and 97 can be ensured.

Next, the operation of each unit during a jam clearance operation near the fixing unit will be described. When a jam occurs, the release lever 30 is first turned in the direction of arrow A as shown in FIG. By the rotation of the release lever 30, the roller 32 on the other end presses the front nip release member 34 to rotate about the nip release shaft 36. The rotation of the nip release member 34 causes the lock member to move.
34b once rotates the hook member 37 to the position shown by the two-dot chain line, fits into the notch 37a, and the nip releasing member 34 is locked in the engaged state. A driven roller support member 67 is provided in the upper U-shaped notch 34a of the front nip release member 34.
The nip release support shaft 70 fixed to the front side is engaged, and is pushed down by the rotation of the front nip release member 34, so that the driven roller 66 is separated from the heat roller 57 and the nip is released.
Although not shown, the nip is similarly released on the rear side by the rotation of the cam member 33 integrated with the release lever 30.

On the other hand, the link mechanism including the link A40, the link B41, and the link C42 whose one end is supported by a part of the front nip release member 34,
The state shown by the solid line in the figure is the notch 4 of the link C42.
The lock lever 44 engaged with 2a also rotates about the pivot B43 as shown in FIG. 19, and the engagement between the notch 44a and the lock pi 45 is released.

Thus, the lock between the apparatus main body 7 and the unit frame 22 is released, and at the same time, the nip between the heat roller 57 and the driven roller 66 in the fixing cartridge 19 is also released.
The unit frame 22 can be pulled out of the apparatus main body 7 without damaging the paper that has been jammed while being nipped by both the transfer unit and the fixing unit, and the jammed paper can be easily removed.

Next, re-attachment of the unit frame 22 to the apparatus main body 7 after the jam processing will be described. When the drawn-out unit frame 22 is moved toward the apparatus main body 7, the arm portion 38c of the rear hook member 38 abuts on the lock set member 46 and is rotated as shown by a two-dot chain line in FIG. With this rotation, the lock portion of the rear nip release member 35 is
The engagement of 35b is released, the lock is released, and the operation opposite to the operation at the time of releasing the nip is performed. At this time, since the rear hook member 38 and the front hook member 37 rotate integrally, the front members also operate in the same manner, and the heat roller 57 and the driven roller 66
The nip between them is reformed, and the lock lever 44 returns to the locked position via the link mechanism. When the unit frame 22 is further moved toward the apparatus main body 7, the lock lever 44 is moved.
Is in contact with the lock pin 45, and the lock lever 44 is rotated while abutting on the shape of the tip, and the notch 44a is engaged with the lock pin 45 to be in a locked state.

Next, the operation at the time of replacing the fixing cartridge 19 will be described. The operation up to the operation of pulling out the unit frame 22 from the apparatus main body 7 is exactly the same as the above-described jam processing. In order to remove the fixing cartridge 19 after the unit frame 22 is pulled out, first, the reversing and discharging unit 20 is rotated as shown by a two-dot chain line in FIG. Evacuate 94. Next, the manual nip portion 38b of the rear hook member 38 is pushed in the direction of the arrow J to unlock the front / rear hook members 37, 38 and the front / rear nip releasing members 34, 35. Then, the user holds the handles 52a and 53a of the fixing cartridge 19 and lifts it up. At that time, the front / rear nip releasing members 34 and 35 rotate as shown in FIG. 20 until the nip releasing support shaft 70 is disengaged from the U-shaped notches 34a and 35a, and the pressing force is applied to a stopper (not shown). Holds that state.

Next, a new fixing cartridge 19 is mounted. However, the unused fixing cartridge 19 is brought into a state where the nip is released by a link mechanism such as the initial release link 72 and the initial release lever 73 as shown in FIG. Has become. This is to prevent deformation of the driven roller 66 due to long-term storage. When the new fixing cartridge 19 is inserted from the opening of the unit frame 22 to be mounted, the U-shaped notch 60a of the tie plate 60, the reference pins 81 and 82, and the contact plates 83 and
The nip release support shaft 70 engages with the U-shaped notches 34a, 35a of the nip release members 34, 35 while being guided by 84, and the nip release members 34, 35 rotate until the lowering of the fixing cartridge 19 stops. I do. In addition, the initial release lever 73 is pushed up by the push-up member 85 by this lowering, and rotates around the support shaft 75.
With this rotation, the support shaft 74 and the initial release link 72 also move,
When the support shaft 74 crosses a straight line passing through the initial release link support shaft 71 and the support shaft 75, the initial release lever 73 further rotates due to the tension of the nip spring 69, whereby the support shaft 74 also rotates upward to engage the nip. Activated. Further, the cartridge connector 111 is connected to the unit connector 113 in conjunction with the mounting by the lowering.

FIG. 21 is a diagram showing another configuration example of the initial release mechanism of the fixing cartridge. As shown in FIG.
A spindle 1 with the center of 1 fixed to the fixing cartridge side plate 53
At one end, the pin 124 is engaged with a U-shaped notch 123a provided on the driven roller support member 123, and in this state, the pin 124 is fixed at a position where the nip portion is released. Are arranged so as to abut against the push-up member 85. When the fixing cartridge is stored, the pin 124 is engaged with the U-shaped notch 123a provided in the driven roller support member 123, and the nip is released. Then, when the fixing cartridge 19 is lowered from the opening to mount the fixing cartridge 19, the push-up member 85
Pushes up the other end of the plate 121 so that the plate 121
, The pin 124 and the driven roller support member 123 are disengaged from each other, and a nip is applied. With this configuration, the number of parts is reduced, and the cost can be reduced.

FIG. 22 is a diagram showing still another configuration example of the initial release mechanism of the fixing cartridge. This configuration example is a nip spring 12
5 is constituted by a compression coil spring, one end of which is fixed to the unit base 26 side of the unit frame 22 and the other end is in contact with a part of the driven roller support member 126 to be compressed when the fixing cartridge 19 is mounted. And a predetermined nip pressure is obtained by the compression. 127 is a stopper pin for restricting the rotation of the driven roller support member 126 when not mounted.When the driven roller support member 126 is in contact with the stopper pin 127, the heat roller 57 and the driven roller 66 It is fixed at a position where it is separated. With this configuration, the number of components included in the fixing cartridge that needs to be replaced is reduced, and the cost can be further reduced.

〔The invention's effect〕

As described above based on the embodiment, according to the present invention, the roller fixing device is held in the apparatus main body via the positioning means by its own weight, and the driven gear provided in the fixing device is provided in the apparatus main body. In the image forming apparatus configured to be driven by the driving gear, the driving force of the driving gear with respect to the driven gear at the meshing position has a downward component force, and the positioning of the roller fixing device is performed via the driven gear. Since the roller fixing device is configured to be pressed against the device, the roller fixing device is positioned by the positioning device by dropping the roller fixing device to the mounting position of the apparatus main body, and is held by the apparatus main body by its own weight, and is also attached to the apparatus main body. When a driving force having a downward component force is transmitted from the provided driving gear to the driven gear, the fixing device itself is driven by its own weight. The roller fixing device held by the roller fixing device is further pressed to the positioning means, so that the roller fixing device is more stably held by the apparatus main body, and the mounting holding member for holding the roller fixing device by pressing it from above. Becomes unnecessary.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an embodiment of an image forming apparatus according to the present invention, FIG. 2 is a view showing a configuration of a support portion of the unit frame, and FIG. FIG. 4 is a perspective view showing a unit frame and a lock mechanism, FIG. 5 is a view showing an engagement mode between a lock set member and a hook member, and FIG. 6 is a paper guide section after transfer. FIG. 7 is a sectional view of a fixing cartridge, FIG. 8 is a perspective view thereof, FIG.
FIG. 10 is a perspective view showing the configuration of the blade, FIG. 10 is a cross-sectional view showing how the fixing cartridge is mounted in the unit frame, and FIG. 11 shows how the reference pin and the tie plate are engaged and positioned. FIG. 12 is a perspective view showing a heat roller peeling claw cassette and a mounting portion thereof, FIG. 13 is a sectional view of the claw cassette, FIG. 14 is a view showing a driving force transmitting mechanism to a fixing cartridge, and FIG. FIG. 15 is a perspective view showing a discharged sheet in which a waving phenomenon has occurred, FIGS. 16 (A) and (B) are views showing an example of an inappropriate configuration of a reversing roller, and FIG. 17 is a nip release at the time of jam processing. Figures showing operation modes, FIG. 18 and FIG.
FIG. 20 is a diagram showing an unlocking operation of the unit frame at the time of jam clearance. FIG. 20 is a diagram showing a mode of detaching the nip releasing support shaft from the nip releasing member at the time of raising the fixing cartridge, FIGS. 21 and 22. The figure is a diagram illustrating another configuration example of the initial release mechanism of the fixing cartridge. In the figure, 1 is a dielectric drum, 2 is a recording head, 3 is a developing device, 4 is a transfer roller, 7 is an apparatus main body, 19 is a fixing cartridge, 20 is a reversing discharge unit, 22 is a unit frame,
26 is a unit base, 27 is a front plate, 28 is a rear plate, 30 is a release lever, 33 is a cam portion, 34 is a front nip release member, 35 is a rear nip release member, 37 and 38 are hook members, and 40 is a link. A, 41 is link B, 42 is link C, 44 is lock lever,
45 is a lock pin, 46 is a lock set member, 52 and 53 are fixing plate side plates, 54, 55 and 56 are tie plates, 57 is a heat roller, 60 is a unit frame tie plate, 61 is a thrust reference pin, and 63 is a heat roller. Drive gear, 66 is a driven roller,
67 is a driven roller support member, 69 is a nip spring, 70 is a nip release support shaft, 72 is an initial release link, 73 is an initial release lever,
81 and 82 are reference pins, 83 and 84 are contact plates, 85 is a push-up member, 106
Denotes an output gear, 111 denotes a cartridge connector, and 113 denotes a unit connector.

Claims (1)

(57) [Claims] A roller fixing device for fixing the toner image on the sheet by nipping and conveying the sheet on which the toner image has been transferred between a pair of rollers; Positioning means fixed to the apparatus main body, which abuts on the roller fixing device when mounting so as to be held by the roller fixing device. In an image forming apparatus configured such that a driving gear provided on the apparatus main body meshes with a driven gear provided on a fixing device to transmit a driving force to the roller, The driving force of the driving gear has a downward component force, and presses the roller fixing device to the positioning means via the driven gear, so that the mounting of the roller fixing device to the apparatus main body is reduced. An image forming apparatus characterized by being configured to reduction.