JP2003345160A - Fixing device - Google Patents

Abstract

An object of the present invention is to prevent a reverse rotation of a heating roller and a take-up shaft and maintain a normal running of a cleaning tape. A heating roller, a pressure roller that conveys a recording sheet in cooperation with the heating roller and fixes a toner image formed on the recording sheet, a cleaning tape in a roll shape, and a cleaning roller. Support shaft 11 for supporting tape
A winding shaft 12 for winding the cleaning tape drawn from the support shaft; a pressing shaft 13 for bringing the cleaning tape running from the support shaft to the winding shaft into contact with a heating roller; A one-way clutch provided in the rotation drive mechanism to prevent the heating roller from rotating in a direction opposite to the recording paper conveyance direction, and a tape winding direction of the winding shaft. Has a ratchet and a non-return pawl for preventing rotation in the reverse direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device provided in an image forming apparatus.

[0002]

2. Description of the Related Art A heating and pressurizing system is used as a fixing device provided in an image forming apparatus such as a printer adopting an electrophotographic system. This type of fixing device is provided with a heating roller having a heater and a pressure roller that is in contact with the heating roller, and conveys the recording paper on which the toner image is formed and passes it between both the rotating rollers to rotate the toner. The image is heated by the heating roller and pressed by the pressure roller to be fixed on the recording paper.

In this fixing device, since the toner image on the recording paper comes into direct contact with the heating roller, the toner adheres to the surface (peripheral surface) of the heating roller when the toner image is formed, and the toner is subsequently fixed. Doing so will stain the recording paper.

Therefore, in the fixing device, as one of the methods for removing the toner adhering to the peripheral surface of the heating roller, a cleaning tape made of aramid fiber or the like is used to continuously rotate the peripheral surface of the heating roller as the heating roller rotates. There is a wiping method. That is, this cleaning method is provided with a support shaft for supporting the cleaning tape, a take-up shaft for winding the cleaning tape, and a holding shaft for bringing the cleaning tape into contact with the heating roller, and the cleaning tape in a roll shape is supported by the support shaft. The cleaning tape is supported, pulled out from the support shaft and run, and is brought into contact with the peripheral surface of the heating roller by the pressing shaft, and then wound by the winding shaft. in this case,
The cleaning tape is wound by the winding shaft so that it runs in the direction opposite to the rotating direction of the heating roller at the contact portion with the heating roller. This is because when the cleaning tape travels in the direction opposite to the heating roller, the cleaning tape receives resistance from the heating roller and can strongly wipe off the toner adhering to the heating roller. The winding shaft is forcibly rotated by the rotation driving mechanism to wind the cleaning tape.

[0005]

The method of cleaning the heating roller in this manner has the following problems.

In the heat and pressure type fixing device, when the recording paper cannot be moved while passing between the heating roller and the pressure roller and is jammed, the heating roller and the pressure roller are manually moved in the recording paper conveyance direction. Or, rotate it in the opposite direction to pull out the jammed recording paper from between both rollers.

Here, when the heating roller is rotated in the direction opposite to the recording paper conveyance direction in order to pull out the jammed recording paper, the rotation direction of the heating roller is cleaned at the portion where the heating roller and the cleaning tape come into contact with each other. It becomes the direction to pull out the tape. Therefore, the cleaning tape receives a force in the pull-out direction due to the rotation of the heating roller, is pulled out from the support shaft, and is pulled out to the take-up shaft side through the contact portion between the heating roller and the pressing shaft. In this case, since the winding shaft is stopped, the drawn cleaning tape is stagnated in the space between the winding shaft and the contact portion between the heating roller and the pressing shaft.

Then, when the heating roller is rotated in the recording paper conveying direction after the paper jam has been dealt with, the cleaning tape which has stagnated in the space between the contact portion between the heating roller and the pressing shaft and the take-up shaft is removed. A force in a direction opposite to the pull-out direction is applied to the portion, and this cleaning tape portion may be pulled by the heating roller and may be caught in the contact portion between the heating roller and the pressing shaft. In this state, it becomes difficult to run the cleaning tape normally.

Further, in the fixing device, in order to rotate the winding shaft in the tape winding direction, the rotation of the electric motor is transmitted to the winding shaft via the gear. However, when the teeth of the gear for rotation transmission are damaged, the rotation of the electric motor is not transmitted to the winding shaft via the gear. Then, the take-up shaft is rotated in the direction opposite to the take-up direction by the action of the tension of the cleaning tape to be taken up, and the cleaning tape taken up by the take-up shaft may be discharged. Also in this case, when the heating roller is rotated in the paper conveying direction, the ejected cleaning tape portion may be caught in the contact portion between the heating roller and the pressing body. In this state, it becomes difficult to run the cleaning tape normally.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fixing device which prevents the heating roller and the take-up shaft for the cleaning tape from rotating in the reverse direction and keeps the cleaning tape running normally.

[0011]

According to a first aspect of the present invention, there is provided a fixing device including a heating roller and a pressure roller which cooperates with the heating roller to convey the recording paper and fix the toner image formed on the recording paper. A roll-shaped cleaning tape, a supporting shaft for supporting the cleaning tape, a winding shaft for winding the cleaning tape unwound from the supporting shaft, and a traveling shaft for traveling from the supporting shaft to the winding shaft. The heating roller is provided with a pressing body that brings the cleaning tape into contact with the heating roller, and a rotation drive mechanism that rotationally drives the heating roller in the recording paper conveyance direction. A heating roller reverse rotation prevention means for preventing rotation in the reverse direction and a winding shaft reverse rotation prevention means for preventing rotation of the winding shaft in a direction opposite to the tape winding direction are provided. It is characterized in.

According to the structure of the present invention, it is possible to prevent reverse rotation of the heating roller and the winding shaft for the cleaning tape.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to the drawings.

The fixing device of this embodiment employs a heating and pressing roller system and is provided inside the main body of the image forming apparatus. FIG. 1 is a diagram schematically showing the fixing device of this embodiment.

In FIG. 1, 1 is a heating roller and 2 is a pressure roller. The heating roller 1 is heated by a heater (not shown) provided inside, and is arranged horizontally and rotatably supported by an image forming apparatus main body (not shown) or a member provided in the main body, and is rotated by a rotary drive mechanism. It is rotated in the recording paper conveyance direction indicated by the arrow. This rotary drive mechanism will be described later. The pressure roller 2 is horizontally arranged below the heating roller 1 in parallel with the heating roller 1, and is rotatably supported by the image forming apparatus main body or a member provided in the main body.
Elastic force is applied to the heating roller 1 by an elastic member (not shown). Therefore, the peripheral surface of the pressure roller 2 contacts the peripheral surface of the heating roller 1. The pressure roller 2 is driven by the rotation of the heating roller 1 and is rotated in the recording paper conveyance direction indicated by an arrow in the drawing.

In the image forming apparatus, the toner image formed on the photoconductor is transferred onto the recording paper P by the transfer device. The recording paper P is conveyed to the heating roller 1 from one side in the direction of the arrow in the figure with the orientation such that the surface having the toner image is the upper surface, and the peripheral surface of the heating roller 1 and the peripheral surface of the pressure roller 2 are conveyed. After passing through the contact portion with the surface, it is further conveyed to the other side of the heating roller 1. When the recording paper P passes through the contact portion between the peripheral surface of the heating roller 1 and the peripheral surface of the pressure roller 2, the toner image is heated and pressed to be fixed on the recording paper P. Heating roller 1
Paper dust of the recording paper P, toner forming a toner image, and the like adhere to the peripheral surface of the recording paper P. A cleaning mechanism 3 is provided that cleans the peripheral surface of the heating roller 1 using the cleaning tape S to remove toner and the like adhering thereto.

The cleaning mechanism 3 will be described with reference to FIGS. 4 and 5. FIG. 4 is a side view showing a support shaft and a winding shaft for the cleaning tape, and FIG. 5 is a plan view of the same.

The cleaning mechanism 3 includes a cleaning tape S, a support shaft 11, a winding shaft 12, and a holding shaft 13.
And is provided above the heating roller 1.
The cleaning tape S is formed of aramid fiber and has a long strip shape (for example, 22 m) having a width close to the length of the heating roller 1, and is wound in a roll state in a product state.

The support shaft 11 is arranged on the upper side of the heating roller 1 on the recording paper carry-in side in parallel with the axis of the heating roller 1.
It is detachably supported by the support member 14. Winding shaft 1
Reference numeral 2 is arranged on the upper side of the heating roller 1 on the recording paper discharge side in parallel with the axis of the heating roller 1, and is rotatably and detachably supported by the support member 14. This winding shaft 12
Is rotated in the tape winding direction by a rotation drive mechanism. This rotary drive mechanism will be described later. The support member 14 is made of a rectangular plate member having a length corresponding to the length of the heating roller 1 and a width larger than the distance between the shafts 11 and 12, and both ends have both shafts 1.
It has a bearing plate 15 for supporting the ends of the first and the second parts. The supporting member 14 is horizontally disposed above the heating roller 1 in parallel with the heating roller 1 and is detachably attached to the main body of the image forming apparatus or a member provided in the main body. FIG. 5 shows only one end of the support member 14. A pressing shaft 13, which is an example of a pressing body, is positioned almost directly above the heating roller 1 and is horizontally disposed in parallel with the heating roller 1 and is supported by the main body of the image forming apparatus or a member provided on the main body. The presser shaft 13 does not rotate and makes sliding contact with the peripheral surface of the heating roller 1.

The support shaft 11 rotatably supports the cleaning tape S in a roll shape. The cleaning tape S is pulled out from the roll portion, is passed through the lower side of the pressing shaft 13, is pressed by the pressing shaft 13, and contacts the peripheral surface of the heating roller 1. Further, the tip of the cleaning tape S is attached to the winding shaft 12.

When the winding shaft 12 rotates in the tape winding direction, a force is applied to the cleaning tape S toward the winding shaft. The cleaning tape S is pulled out from the support shaft 11 and runs, then passes through the contact portion between the heating roller 1 and the pressing shaft 13, is pressed by the pressing shaft 13, and runs while contacting the peripheral surface of the heating roller 1. The cleaning tape S is finally wound around the winding shaft 12 that rotates in the tape winding direction.

When the cleaning tape S travels in contact with the peripheral surface of the heating roller 1, it adheres to the peripheral surface of the heating roller 1 by wiping off adhered substances such as toner and removes it from the peripheral surface of the heating roller 1. When the heating roller 1 rotates in the recording paper conveyance direction and the cleaning tape S runs from the support shaft 11 toward the take-up shaft 12, cleaning is performed at the contact portion between the cleaning tape S and the peripheral surface of the heating roller 1. The running direction of the tape S and the rotating direction of the heating roller 1 are opposite to each other. Therefore, the cleaning tape S can apply a resistance force to the peripheral surface of the heating roller 1 to reliably remove the deposits on the peripheral surface. The pressing shaft 13 does not rotate and stands still to press the cleaning tape S and press the heating roller 1
Contact the peripheral surface of.

In the image forming apparatus of the present invention, the rotation driving mechanism for rotating the heating roller 1 in the recording sheet conveying direction prevents the heating roller 1 from rotating in the direction opposite to the recording sheet conveying direction. Equipped with blocking means. In this embodiment, a one-way clutch is provided as the heating roller reverse rotation preventing means.

FIG. 2 is a side view schematically showing a mechanism for rotationally driving the heating roller, and FIG. 3 is the same plan view. In FIG. 2 and FIG. 3, reference numeral 21 is a rotary drive mechanism, and this rotary drive mechanism 21 transmits the rotation of the electric motor M to the gear 24 provided on the heating roller 1 via the gears 22 and 23 of a plurality of stages, and the heating roller 1 is driven. Is rotated in the recording paper conveyance direction. The electric motor M and the gears 22 and 23 are supported by the image forming apparatus main body or members provided in the main body. The gear 24 is formed on the outer peripheral portion of one end of the heating roller 1. A one-way clutch 25 that is combined with the gear 23 is provided on the side of the gear 23 that meshes with the gear 24 provided on the heating roller 1.

The one-way clutch 25 permits rotation of the heating roller 1 of the gear 23 in the direction of rotation of the recording paper conveyance direction and prevents rotation in the opposite direction. As a result, the gear 24 and the heating roller are rotated. This allows the rotation of the first recording sheet in the conveying direction and prevents the rotation in the opposite direction.
The one-way clutch 25 employs a ratchet type one-way clutch or the like. The one-way clutch 25 is supported by the main body of the image forming apparatus or a member provided in the main body, and the rotary shaft located on the central axis rotates the gear 23. It is connected to the shaft.

When the recording paper P is conveyed in order to fix the toner image in the rotary drive mechanism 21 provided with the one-way clutch 25 as the heating roller reverse rotation prevention means as described above, the rotation of the electric motor M is rotated by the gears 22 to 22. The heat roller 1 is transmitted by means of 24 to rotate the heating roller 1 in the recording paper conveyance direction. Then, when the drive of the electric motor M is stopped and the rotation transmission to the heating roller 1 is stopped, if the heating roller 1 is attempted to rotate in the direction opposite to the recording paper conveyance direction, the gear 24 is also integrated in the opposite direction. Although the gear 23 tries to rotate in the opposite direction, the one-way clutch 25 prevents the gear 23 from rotating in the opposite direction, so that the gear 24, that is, the heating roller 1 is prevented from rotating in the opposite direction.

In this fixing device, the electric motor M is driven when the recording paper P cannot pass due to some reason and is jammed while the recording paper P is passing between the heating roller 1 and the pressure roller 2. Even if the heating roller 1 and the pressure roller 2 are stopped and rotated in the direction opposite to the recording paper conveyance direction so as to extract the recording paper P from between the rollers 1 and 2, the heating roller 1
The rotation in the opposite direction is blocked and remains stopped. Therefore, when the heating roller 1 is manually rotated in the recording paper conveyance direction, the pressure roller 2 is also driven and rotated in the same direction, so that the recording paper P can be pulled out from between both rollers 1, 2.

Therefore, as in the conventional case, the heating roller 1 is rotated in the reverse direction in order to deal with the paper jam, and the cleaning tape S is caught between the heating roller 1 and the pressing shaft 13 to hinder the running. It is possible to avoid the occurrence of situations.

As described above, when the one-way clutch 25 is used as the heating roller reverse rotation preventing means, the heating roller reverse rotation preventing means can be provided in the rotation drive mechanism in a small space, and the reverse rotation of the heating roller 1 can be reliably prevented. .

Further, in this image forming apparatus, the winding shaft 1
It is equipped with a winding shaft reverse rotation preventing means for preventing the rotation of the tape 2 in the direction opposite to the tape winding direction. In this embodiment,
A ratchet wheel and a check claw are provided as the winding shaft reverse rotation preventing means. A description will be given by adding FIG. 6 to FIGS. 4 and 5. FIG. 6 is a perspective view showing a ratchet wheel and a check claw.

In FIGS. 4 to 6, 31 is a ratchet wheel and 32
Is a check claw, 33 is a mounting body for attaching the check claw 32, 34
Is a gear (omitted in FIG. 4). The gear 34 is the winding shaft 1.
It is attached to one end of 2 and meshes with a gear that constitutes a rotary drive mechanism that rotationally drives the heating roller 1 described above, or a gear that constitutes another rotary drive mechanism (neither is shown). The rotation of these rotary drive mechanisms is transmitted to the gear 34, and the winding shaft 12 is rotated together with the gear 34 in the tape winding direction for winding the cleaning tape S.

The ratchet wheel 31 has a gear 3 at one end of the winding shaft 12.
4 is mounted side by side and fixed to, for example, a gear 34, and the ratchet wheel 31 rotates integrally with the gear 34 and the winding shaft 12. A plurality of claws 31a are formed side by side in the circumferential direction on the outer peripheral portion of the ratchet wheel 31. These claws 31a are provided with a vertical surface along the radial direction, and the winding shaft 12 from the outer peripheral end of this vertical surface.
Has an inclined surface inclined from the outer periphery toward the center toward the front (downstream side) in the rotating tape winding direction. The check claw 32 is made of, for example, a leaf spring. Check claw 3
2 is a claw 31a of the ratchet 31 near the outer periphery of the ratchet 31
Are arranged along the circumferential direction to face the outer peripheral surface of the. The non-return pawl 32 has a base end portion attached to a part of the support member 14 by a mounting body 33, for example, to the bearing plate 15 by means such as screwing, and a portion from the base end portion to the tip end of the ratchet wheel 31. It is inclined along the inclined surface of the claw 31a. As a result, the check claw 32 is always in contact with the inclined surface of each claw 31a of the ratchet wheel 31 from outside by elastic force and is engaged with the claw 31a.

When the ratchet wheel 31 rotates in the winding direction of the cleaning tape S, the claw 31a of the ratchet wheel 31 moves in the tape winding direction with the inclined surface facing forward in the direction of rotation, and the nail 31a.
The inclined surface pushes the check claw 32 outward against the elastic force to elastically deform it. As a result, the pawl 31a pushes the non-return pawl 32 and moves forward with the rotation of the ratchet wheel 31. The non-return pawl 32 elastically deforms outward with the base end as a fulcrum, rides over the apex of the inclined surface of the pawl 31a of the ratchet wheel 31, and returns to its original state by elasticity again to the inclined surface of the next pawl 31a. Abut. In this way, when the ratchet wheel 31 rotates in the direction of winding the cleaning tape S, each of the pawls 31a sequentially pushes away the non-return pawl 32 and passes therethrough, so that the ratchet wheel 31 can rotate. That is, the winding shaft 12 can rotate in the direction in which the cleaning tape S is wound.

When the ratchet wheel 31 tries to rotate in the direction opposite to the tape winding direction, the ratchet 31a tries to move in the opposite direction with its vertical surface facing the front side in the direction of rotation. The tip of the check claw 32 abuts the vertical surface of the claw 31a at a substantially right angle. In this state, the non-return pawl 32 is pushed by the vertical surface of the pawl 31a and is pushed by the ratchet wheel 31a.
Does not elastically deform toward the outside, and receives the vertical surface of the claw 31a to prevent its movement. That is, the check claw 32 is the claw 3
The movement of 1a is blocked to prevent the ratchet wheel 31 from rotating in the opposite direction. Thus, when the ratchet wheel 31 tries to rotate in the direction opposite to the direction in which the cleaning tape S is taken up, the check claw 3
2 inhibits the movement of the pawl 31a to prevent the pawl wheel 31 from rotating, and the winding shaft 12 together with the pawl wheel 31 is prevented from rotating in a direction opposite to the tape winding direction.

When the teeth of the gear forming the rotary drive mechanism for rotating the take-up shaft 12 in the tape winding direction are damaged, the take-up shaft 1 is pulled by the cleaning tape S.
A force that rotates in the opposite direction is applied to 2. However, the check claw 32
Prevents the winding shaft 12 from rotating in the opposite direction. In this way, the take-up shaft 12 is prevented from rotating in the direction opposite to the tape take-up direction, so that the cleaning tape S wound by the take-up shaft 12 is discharged from the take-up shaft 12 and the cleaning tape S travels. It can prevent the occurrence of trouble.

When the ratchet wheel 31 and the check claw 32 are used as the winding shaft reverse rotation preventing means, the winding shaft reverse rotation preventing means is attached to the winding shaft 12 in a small space by directly attaching the ratchet wheel 31 to the winding shaft 12. It is possible to surely stop the rotation of the winding shaft 12 in the opposite direction by directly combining them.

Further, in the structure in which the support shaft 11 and the take-up shaft 12 are supported by the common support member 14, the ratchet wheel 31 and the check claw 32 can be supported by the support member 14, whereby the ratchet wheel 31 and The check claw 32 may be integrally combined with the winding shaft 12 to form a unit. Therefore, the structure for providing the ratchet wheel 31 and the check claw 32 is simplified, and the assembly and disassembly work for supporting the ratchet wheel 31 and the check claw 32 becomes convenient.

The present invention is not limited to the above-described embodiments, but can be implemented with various modifications.

[0039]

According to the fixing device of the present invention, the heating roller reverse rotation preventing means prevents the heating roller from rotating in the direction opposite to the winding direction of the recording paper tape. It is possible to prevent the occurrence of a situation in which the cleaning tape is rotated in the opposite direction to hinder the running of the cleaning tape, and the winding shaft reverse rotation preventing means prevents the situation in which the winding tape is reversed to hinder the running of the cleaning tape. .

Therefore, it is possible to prevent the heating roller and the take-up shaft from rotating in the reverse direction and to keep the cleaning tape running normally.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a fixing device according to an embodiment of the present invention.

FIG. 2 is a side view schematically showing the rotation driving mechanism of the heating roller according to the same embodiment.

FIG. 3 is a plan view schematically showing the rotation driving mechanism of the heating roller according to the same embodiment.

FIG. 4 is a side view showing a support shaft and a winding shaft in the same embodiment.

FIG. 5 is a plan view showing a support shaft and a winding shaft in the same embodiment.

FIG. 6 is a perspective view showing a ratchet wheel and a check claw according to the embodiment.

[Explanation of symbols]

1 ... Heating roller 2 ... Pressure roller 3 ... Cleaning mechanism 11 ... Support shaft 12 ... Winding shaft 13 ... Presser shaft (presser body) 14 ... Support member 21 ... Rotational drive mechanism 22 ... Gear 23 ... Gear 24 ... Gear 25 ... One-way clutch 31 ... Claw wheel 32 ... Non-return claw 33 ... Mounting body

Claims (3)

[Claims] 1. A heating roller, a pressure roller that cooperates with the heating roller to convey a recording sheet and fix a toner image formed on the recording sheet, a cleaning tape in a roll shape, and the cleaning tape. A supporting shaft that supports the winding shaft, a winding shaft that winds the cleaning tape unwound from the supporting shaft, a pressing body that makes the cleaning tape running from the supporting shaft to the winding shaft contact the heating roller, and A rotation driving mechanism for rotating the heating roller in the recording sheet conveying direction, and a heating roller reverse rotation preventing means provided in the rotation driving mechanism for preventing the heating roller from rotating in a direction opposite to the recording sheet conveying direction. A fixing device, comprising: a winding shaft reverse rotation preventing means for preventing rotation of the winding shaft in a direction opposite to a tape winding direction. 2. The heating roller reverse rotation prevention means is a one-way clutch, and the winding shaft reverse rotation prevention means engages with a ratchet wheel attached to the winding shaft and a claw formed on the ratchet wheel. The fixing device according to claim 1, further comprising: a check claw that prevents the winding shaft from rotating in a direction opposite to a tape winding direction. 3. The support shaft and the winding shaft are supported by a common supporting member, the ratchet wheel is provided on the winding shaft, and the check claw is mounted on the supporting member. The fixing device according to claim 2.