JP2009037078A - Fixing device and image forming apparatus equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To save on space by removing offset toner on a pressure roller with a configuration simultaneously having two means of a cleaning web and a cleaning roller and effectively performing the offset recovery of the cleaning roller. <P>SOLUTION: The fixing device is provided with: a fixing section which fixes a toner image on a record medium S, while passing the record medium S between a heating member 30 and a pressure member 32; and a cleaning section 40 which removes toner adhering to the pressure member 32. The cleaning member 41 of the cleaning section 40 for removing the toner adhering to the pressure member 32 comprises a winding type web, the web is wound onto a web take-up shaft 42, in such a manner that the surface of the web brought into contact with the side of the pressure member 32 is turned inward and a cleaning roller 43 comes into contact with the surface of the web wound by the web take-up shaft 42. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fixing device for fixing a toner image on a recording medium while conveying the recording medium after image transfer between a heating member and a pressure member in an image forming apparatus, and a copying machine including the fixing device. The present invention relates to an image forming apparatus such as a printer, a printer, a facsimile, or a complex machine thereof.

For example, an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine, or a complex machine thereof forms a toner image sequentially on an image carrier by repeating charging, writing, developing, transferring, cleaning, discharging, etc. The toner image is sequentially transferred to record the image on a recording medium such as a sheet / OHP film.
Such an electrophotographic image forming apparatus is equipped with a fixing device for fixing a toner image transferred onto a recording medium thereon, and in such a fixing device, the toner image is attached to a heating member and a pressure member. It has been proposed to use an offset toner cleaning method that prevents the toner from being reversely transferred to the recording medium again or insufficiently collected (see, for example, Patent Documents 1 and 2).
Conventionally, a fixing device using heat and pressure presses a pressure roller to a fixing roller including a heat source therein, and passes a transfer sheet on which an unfixed toner image is placed between the rollers, thereby transferring the toner. The technology to fix it on paper is the mainstream.
The fixing roller surface is devised to prevent toner adhesion, such as fluorine coating, but depending on conditions such as the environment and transfer paper, a phenomenon called offset, in which this toner slightly adheres to the fixing roller from the transfer paper May happen.
It is known that the offset toner remains on the fixing roller and the pressure roller in contact therewith, and is eventually transferred back to the transfer paper to stain the image. In order to prevent this, the fixing roller is provided with a cleaning member such as a cleaning web or a cleaning roller. The cleaning member is in pressure contact with the fixing roller and the pressure roller, and collects the offset toner.

Patent Document 1 discloses an example of a conventional cleaning web system in which a web wound around a feed roller is brought into contact with a heating member by a pressing roller and cleaned while being collected by a winding shaft.
In recent years, the fuser has been cut off from the heat source (heater) during standby to support zero energy standby mode (ZERO) and to save energy. Then, the fixing roller or the like is heated to a temperature at which the toner is fixed.
Therefore, the fixing roller or the like is thinned to 1 mm or less to improve the temperature responsiveness, shorten the time until fixing is possible to about 10 seconds, and the specifications are both user-friendly and energy-saving. In such a configuration, since the heat capacity of the fixing roller is small, it is easily affected by heat transfer to the transfer paper, the contact member of the fixing roller, the flow of air, etc., and the temperature distribution is likely to change greatly depending on the part.

There are several temperature control means installed on the fixing roller to make the temperature distribution uniform, but the entire area of the fixing roller can be uniformly controlled according to the size and mode. It is impossible to arrange the means because of space and cost.
If the temperature distribution of the fixing roller becomes uneven, the occurrence of offset due to mismatching of the fixing conditions and the life of the fixing roller due to thermal deterioration are likely to be shortened. Of these, the most serious problem is the reverse transfer to the transfer paper by remelting the toner mass accumulated on the cleaning roller in the toner using the polymerization method.
This problem is a phenomenon that occurs remarkably in the case of a small size compared to the maximum size that can be passed. In other words, since the small size has a small area in contact with the fixing roller, the temperature is deprived only in a narrow range of the fixing roller, and as a result, the temperature of the fixing roller in the non-sheet passing portion does not decrease, and the temperature only in the sheet passing portion. descend.
Then, since the temperature detection means corresponding to that portion instructs the heater to be turned on, the temperature of the non-sheet passing portion rises unnecessarily, and the toner adhering to the corresponding portion of the cleaning roller also melts and reversely transfers. .

On the other hand, with the energy saving of the fixing device, the toner used is also decreasing in melting point. Although it has become possible to set the fixing temperature lower than before due to the low melting point, it can be said that it becomes sensitive to the temperature distribution of the fixing roller and offset is likely to occur.
Furthermore, to reduce the particle size of the toner for higher image quality and further to the polymerization toner, progress is being made to the polymerization toner, but it goes without saying that the offset becomes worse as the toner becomes smaller. The toner also has a characteristic of being easily offset.
When the offset toner increases, the toner adheres to the separation claw and the thermistor. In the configuration in which the web is in contact, the toner image is reversely transferred from that portion to the fixing roller, and the toner is collected on the web.
However, there is a limit to the amount of toner collected on the web, and if the amount of offset toner increases, the toner blocked by the web and the fixing roller or pressure roller will slip out and adhere to the image. It causes abnormal images called missing images. For this reason, it is possible to cope with a new surface always hitting the fixing roller by increasing the amount of winding of the web.
However, when the web winding amount increases, the web unit itself becomes large, the running cost increases, and at the same time, a large space is required in terms of layout, which is disadvantageous.

In the case of a type in which only the cleaning roller is in contact with the fixing roller or the pressure roller, if the amount of offset toner fixed to the cleaning roller increases, the fixed toner dissolves when heat is applied by continuous paper passing. The viscosity is lowered, and the offset toner is separated from the fixed toner on the surface of the cleaning roller.
As a result, the recovery ability (adhesiveness≈cleanability) may be reduced, or offset toner that has adhered to the cleaning roller may be reversely transferred again to the fixing roller or the pressure roller.
The offset toner is more likely to be generated when the image area is larger. In reverse transfer, particularly when a small size is continuously fed, the temperature of the non-sheet passing portion is likely to be melted first from this portion on the cleaning roller.
The problem of melting out is disadvantageous in the configuration in which the cleaning member is in contact with the fixing roller because the temperature of the cleaning member is higher than in the configuration in which the cleaning member is in contact with the pressure roller.
In the technique of Patent Literature 2, as an effective cleaning method, when the fixing roller temperature is low, the web is separated and contacted at a predetermined temperature or higher.
JP-A-10-333480 Japanese Patent No. 3364555

However, in the case of the technique disclosed in Patent Document 2, the residual toner on the fixing roller may not be completely collected, which may cause an abnormal image.
In such a case, when collecting the residual offset toner on the fixing roller, it is effective to perform idling while keeping the web in contact during non-sheet passing such as during standby. Because idling motor noise and noise are conspicuous, we want to rotate with the load torque as low as possible.
Therefore, in view of the above situation, an object of the present invention is to remove the offset toner on the pressure roller by a configuration having two means of the cleaning web and the cleaning roller at the same time, and to effectively collect the offset of the cleaning roller. It is an object of the present invention to provide a fixing device that implements space saving and an image forming apparatus equipped with the fixing device.

In order to solve the above-described problem, the invention according to claim 1 includes a fixing unit that fixes a toner image on a recording medium while conveying the recording medium between the heating member and the pressing member, and the pressing member. And a cleaning unit that removes toner adhering to the cleaning unit, the cleaning member of the cleaning unit is formed of a take-up type web, and the surface of the web that contacts the pressure member side is The fixing device is characterized by being wound on a web winding shaft with the surface facing inward and having a cleaning roller in contact with the surface of the web wound by the web winding shaft.
According to a second aspect of the present invention, the cleaning roller is in contact with the pressure member when the recording medium passes through the fixing nip, and is driven to rotate by being driven by the pressure member. Features the fixing device described.
According to a third aspect of the present invention, in the fixing device according to the first or second aspect, the cleaning roller can be separated from the pressure member when the recording medium is not passed through the fixing nip. Features.

According to a fourth aspect of the present invention, the cleaning roller is always pressed against the surface of the web of the web winding shaft by an elastic pressing means. Features the fixing device described.
According to a fifth aspect of the present invention, there is provided the fixing device according to any one of the first to fourth aspects, wherein the cleaning roller includes a heat pipe inside and a heat-resistant elastic layer is provided on a surface thereof. And
According to a sixth aspect of the present invention, the cleaning roller is in contact with the pressure member during sheet passing and is separated from the pressure member during non-sheet feeding. Features the fixing device described.
According to a seventh aspect of the present invention, in the fixing device according to any one of the first to sixth aspects, the cleaning roller is driven to rotate while the paper is passed, and the rotational drive is released while the paper is not passed. It is characterized by.
According to the eighth aspect of the present invention, the electrostatic latent image formed on the image carrier is developed and visualized with toner, the visualized toner image is transferred onto a recording medium by a transfer device, and the recording is performed. 8. An image forming apparatus comprising: a fixing device according to claim 1, wherein the toner image on the medium is fixed on the recording medium by heat and pressure, and the recording medium is sent to a next process. Features the device.

  According to the present invention, the web surface on the side in contact with the pressure roller is wound toward the center of the web winding shaft, that is, on the winding shaft. Always shows a clean surface on the back side, and by collecting the offset toner on the cleaning roller on this clean surface, the web can be used effectively without waste, and the consumption of the web is suppressed. It is possible to save space.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic front view showing the overall configuration of an image forming apparatus which is a copying machine equipped with the fixing device of the present invention. That is, as shown in FIG. 1, the image forming apparatus 1 is a monochrome copying machine that reads an image from a document surface of a document and forms a copy image on a recording medium made of various types of paper.
The image forming apparatus 1 includes an image forming apparatus main body 2 that performs predetermined image forming processing based on a read original image, and the image forming apparatus main body 2 that is placed on the main body using a sheet such as a recording sheet or an OHP film. A paper feeding device 3 for supplying a certain recording medium S one by one is provided. In addition, it has a document reading device 4 attached on the image forming apparatus main body 2 for reading a document image and sending the document image information to the image forming apparatus main body 2.
A paper discharge tray 9 is installed in the upper part of the image forming apparatus main body 2, and a conveyance path R <b> 1 is formed as a path for moving the recording medium S from the paper supply device 3 to the paper discharge tray 9.
Most of the transport path R1 extends in a substantially vertical direction, and on the transport path R1, a predetermined interval corresponding to the recording medium S of the minimum size is secured, and a number of transport rollers and roller pairs are configured. Such recording medium (sheet material) conveying means is provided.

The recording medium S on the conveyance path R1 is always conveyed by any recording medium conveying means by nipping or the like. Further, the sheet feeding device 3 is accommodated in each stage of the sheet feeding device 3. A recording medium transport device 5 is installed for feeding the recorded recording medium S to the transport path R1.
In the image forming apparatus main body 2, a photoconductor unit 10 and a fixing device 11 are sequentially arranged and installed in the middle of the transport path R1. The photoconductor unit 10 including the photoconductor drum 10A transfers the generated toner image to the recording medium S transported on the transport path R1.
Thereafter, the fixing device 11 fixes the transferred toner image on the recording medium S, and discharges the recording medium S on which the toner image is fixed to the paper discharge tray 9 positioned at the end of the conveyance path R1. ing. The fixing device 11 includes a heating roller 30, a pressure roller 32, and a cleaning unit 40.

The photoconductor unit 10 has a single drum-like photoconductor 10A that is an image carrier, and the photoconductor drum 10A is formed in a cylindrical shape having a predetermined diameter and is rotatable about a horizontal axis. It is supported.
The photosensitive drum 10A receives a rotational driving force from a driving source (not shown) such as a motor provided in either the photosensitive unit 10 or the image forming apparatus main body 2, and has a predetermined rotational direction (here, in the drawing). , And is driven to rotate at a constant speed that is stable in the direction of the arrow).
Further, a developing device 12, a transfer device 13, a photoconductor cleaning device, a charge eliminating device, a charging device, and the like are arranged in the order of going around the photoconductor unit 10 and counterclockwise.
Within each rotation of the photosensitive drum 10A in the counterclockwise rotation direction, the development position, the transfer position, the cleaning position, the charge removal position, and the charging position are set sequentially from the upstream to the downstream by each of these devices. Is done.

Further, a latent image forming position is set between the charging position and the developing position, and exposure is performed to write an invisible latent image corresponding to image information by irradiating the latent image forming position with a predetermined laser beam. The apparatus 15 is disposed obliquely below and slightly away from the photoconductor unit 10.
The photosensitive drum 10A is rotationally driven in the counterclockwise direction, and each device and the exposure device 15 synchronize with the rotation of the photosensitive drum 10A to perform a series of images by a predetermined cooperative operation. The formation process is executed.
That is, the developing device 12 has an appropriate configuration such as a developing roller that generates a toner brush in which toner particles are erected radially from the surface thereof. By the above-described image forming process, a latent image is generated at a predetermined location on the surface of the photosensitive drum 10A, and moves on the outer periphery as the photosensitive drum 10A rotates, and passes through the developing position.
At this time, the developing device 12 attaches toner particles at the tip of the toner brush to the latent image so that the invisible latent image is visualized with a monochrome toner image.

The transfer device 13 includes two support rollers that are arranged to face each other at a predetermined distance in a substantially vertical direction, and a transfer belt 17 that is stretched around these support rollers. The toner image on the outer peripheral surface of the photosensitive drum 10A is transferred to a recording medium (paper) S, and the recording medium S on which the unfixed toner image is transferred is conveyed upward.
That is, the lower support roller has a portion around which the transfer belt 17 is wound pressed against a substantially diagonally lower portion of the photosensitive drum 10A, and a portion where the surface of the photosensitive drum 10A and the transfer belt 17 are in contact with each other. The transfer position is set. The upper support roller is disposed in front of the introduction port of the fixing device 11.
The photosensitive member cleaning device 18 is a photosensitive member in contact with the photosensitive member cleaning position or a blade member (not shown) configured such that the blade edge at the tip thereof comes into contact with the cleaning position on the photosensitive drum 10A with a predetermined pressure. The rotating brush (not shown) that rotates following the rotation of the body drum 10A, or both of them, is configured to remove toner or foreign matter remaining on the surface of the photosensitive drum 10A after transfer. Yes.

Although not shown, the static eliminator is mainly composed of a lamp capable of emitting light of a predetermined intensity. The neutralization position is irradiated from this lamp to the neutralization position to release the charged state on the surface of the photosensitive drum 10A passing through the neutralization position, and the surface potential of the photosensitive drum 10A after passing through the transfer position is The initial state is restored.
Note that reference numeral 20 in FIG. 1 denotes a toner storage container including a toner bottle that stores a predetermined amount of new toner. A toner conveyance path (not shown) is formed from the toner container 20 to the developing device 12.
When the developing device 12 consumes the toner in the developing device 12 for development, the developing device 12 is replenished with new toner from the toner storage container 20.
Below the image forming apparatus main body 2 is provided a paper feeding device 3 that can select a paper size automatically according to the size of a document to be read or by manual setting by a user.
In other words, the paper feeding device 3 stores a plurality of paper feeding trays 51 arranged in multiple stages, and each paper feeding tray 51 has different sizes and vertical and horizontal directions with respect to various sizes and recording medium conveyance directions. A plurality of oriented recording media S are stacked and stored.

The document reading device 4 has a predetermined range on the upper surface of the reading device main body formed by the contact glass 57, and optically reads and acquires the predetermined range on the surface of the contact glass 57 in the reading device main body. The reading means for storing is stored.
This reading means includes at least a light source 53 and a mirror 54 of the first traveling body, a mirror 54 of the second traveling body, an imaging lens 55, and a reading sensor 56. A document holding plate 58 configured to be opened and closed between a closed position covering the contact glass 57 and an opened position opened is disposed on the upper surface of the reading apparatus main body.
That is, the document pressing plate 58 has a larger vertical and horizontal dimension than the contact glass 57, and one end thereof is pivotally supported on the upper surface of the reading apparatus main body by a hinge (not shown).
In the copying machine 1 configured as described above, when copying a document, the user manually opens the document pressing plate 58 of the document reading device 4 from the closed position to the opened position.
A document is set on the contact glass 57 of the document reading device 4 and then manually operated in a direction to close the document pressing plate 58. The document set on the contact glass 57 is pressed from above by the document pressing plate 58.
That is, by this, the original is brought into close contact with the contact glass 57 so as to be accurately read, and is spread in a plane, and the original is fixed on the contact glass 57.
Then, when a user turns on a start switch installed in an operation screen (not shown) provided in advance in the image forming apparatus 1, the reading operation of the document reading device 4 is immediately started, and the first travel is performed by a driving mechanism (not shown). The body and the second traveling body are traveled.

Light is emitted from the light source 53 of the first traveling body toward the document, and reflected light from the document surface is directed to the second traveling body. The reflected light is reflected by the mirror 54 of the second traveling body and is input to the optical reading sensor 56 via the imaging lens 55. As a result, the reading sensor 56 reads an image on the original surface.
When the start switch is turned on as described above, the photosensitive drum 10A of the photosensitive unit 10 starts rotating, and a toner image is formed on the photosensitive drum 10A based on the read original image. The operation to start is started.
That is, as the photosensitive drum 10A is rotated, predetermined portions on the outer peripheral surface of the photosensitive drum 10A are sequentially placed on the charging device, the exposure device 15, the developing device 12, the transfer device 13, the photosensitive member cleaning device 18, and the charge eliminating device. Pass through each set position. Thereby, the battery is sequentially charged to a predetermined charged state, a latent image is generated, and the toner image is visualized.

After the toner image is transferred to the recording medium S, residual toner is removed, the charged state is released, and one cycle is completed. Depending on the size of the image to be formed, the cycle is continued for a predetermined period so as to generate a toner image in a range of a predetermined length of the outer peripheral surface in the rotation direction.
On the other hand, when the start switch is pressed, the recording medium transport associated with the paper feeding stage 51 is fed from the paper feeding stage (paper feeding tray) 51 containing the automatically or manually selected recording medium S in the paper feeding device 3. The apparatus 5 conveys one recording medium S to the paper feed path R1 through a predetermined path.
The recording medium S is transported substantially upward on the transport path R1 in the image forming apparatus main body 2 by a transport roller or the like, hits the registration roller 21 and temporarily stops.
On the other hand, in the case of manual sheet feeding, the recording medium S set on the manual tray 24 is first fed out by the rotation of the sheet feeding roller 22 for the manual tray. When a plurality of sheets are stacked and set, they are separated into one sheet by a manual feed tray separating roller 23 and conveyed to the manual sheet feed path R2.
The sheet is conveyed from the manual sheet feeding path R2 to the sheet feeding path R1, and finally comes into contact with the registration roller 21 and stops. Then, the registration roller 21 starts to rotate at an accurate timing in accordance with the relative movement of the toner image on the photosensitive drum 10A that has been rotationally driven, and sends the recording medium S once stopped to the transfer position. As a result, a toner image is transferred onto the recording medium S by the transfer device 13.

The recording medium S to which the unfixed monochrome toner image is transferred is conveyed to the fixing device 11 by the transfer belt 17 of the transfer device 13 that forms a part of the conveyance path R1. The fixing device 11 applies heat and pressure within a predetermined range to fix the toner image on the recording medium S.
The recording medium S on which the toner image is fixed in this manner is guided to the transport path R1 reaching the paper discharge tray 9 by the switching claw 25, and is discharged onto the paper discharge tray 9 by the discharge rollers 26 and 27. Stacked on the paper tray 9.
Further, when the double-sided copy mode is selected by the user's setting input, the recording medium S on which the image is fixed on one side is conveyed to the recording medium reversing device 28 side by the switching claw 25. The recording medium S reciprocates in the recording medium reversing device 28 on a reverse conveyance path R3 formed in advance at a predetermined position by a plurality of roller pairs 29, 31 arranged at a predetermined position and a guide member (not shown).
After the vertical direction of the surface of the recording medium S is reversed, the recording medium S is returned to the transport path R <b> 1 from a position positioned in front of the photosensitive unit 10. After being transported on the transport path R1 and guided again to the transfer position, this time the image is transferred and fixed on the back surface of the recording medium S, and finally discharged onto the discharge tray 9 by the discharge rollers 26 and 27. The

FIG. 2 is a schematic view showing a cleaning unit of the fixing device according to the present invention. FIG. 3 is a schematic view showing a state in which the cleaning roller and the pressure roller of the cleaning unit in FIG. 2 are separated by a distance of ΔL. FIG. 4 is a detailed view showing the cleaning unit.
Referring to FIGS. 2 to 4, the fixing device 11 of FIG. 1 is shown in an enlarged manner. The fixing device 11 is a heating member and includes a heating roller 30 including a heating means and a pressure member. A pressure roller 32 and a cleaning unit 40 are included.
A cleaning device 40 that removes toner adhering to the pressure roller 32 includes a web 41 as a cleaning member. The web 41 is constituted by a take-up web.
The web surface in contact with the pressure roller 32 is wound in a direction toward the center of the web take-up shaft 42, that is, from the web surface onto the web take-up shaft 42, and taken up by the web take-up shaft 42. A cleaning roller 43 is in contact with the surface of the web 41.
The web 41 is made of a heat-resistant nonwoven fabric and impregnated with a release agent such as silicon oil. Further, the web 41 is fed out from the web feed shaft 44 and taken up by the take-up shaft 42 via the pressing roller 45.
As described above, the cleaning surface of the web 41 is in the winding direction facing the center of the web winding shaft 42, that is, the surface of the web 41 on the side in contact with the pressure roller 32, as shown in the figure. Is wound on the web winding shaft 42, and a cleaning roller 43 is in contact with the web winding shaft 42.

In this manner, the surface of the web 41 that is in contact with the pressure roller 32 is wound toward the center of the web winding shaft 42, so that the outer peripheral surface of the web winding shaft 42 is always clean on the back side. A special aspect appears. 2 and 3, the symbol T indicates the toner collected by the web 41.
By collecting the offset toner on the cleaning roller 43 on this clean surface, the web 41 can be used effectively without waste, and the consumption of the web 41 can be suppressed to save space.
2 and 4, the cleaning roller 43 contacts the pressure roller 32 and rotates in the direction of the arrow. When the paper is passed, the cleaning roller 43 is brought into contact with the pressure roller 32 and is driven to rotate so that the offset toner on the cleaning roller 43 is positively collected by the web 41 so that the cleaning roller 43 is always cleaned. It can be kept high.

The cleaning roller 43 is configured to be separated from the pressure roller 32. In FIG. 2, the state which these contact | abut is shown. On the other hand, FIG. 3 shows a state in which the cleaning roller 43 is separated from the pressure roller 32 by a distance of ΔL.
At the time of separation, the web winding shaft 42 and the cleaning roller 43 integrally rotate counterclockwise around the pressing roller 45 axis. Since the web winding shaft 42 includes a one-way clutch or a torque limiter (not shown), the web 41 is prevented from sagging without being reversely rotated by a rotating operation.
Since the cleaning roller 43 can be separated from the pressure roller 32, the temperature of the cleaning roller 43 is lower than when the cleaning roller 43 is always in contact with the pressure roller 32, so that the toner can be prevented from melting.

FIG. 4 shows a state where the cleaning roller 43 presses the web take-up shaft 42 by a pressurizing spring 46 disposed at an appropriate position where pressure is applied to the web take-up shaft 42.
The pressure applied to the web winding shaft 42 by the cleaning roller 43 is integrated with the cleaning roller 43 even when the cleaning roller 43 is separated from the pressure roller 32, as will be described later with reference to FIGS. Therefore, the pressurized state is always maintained.
In this way, since the cleaning roller 43 is always in contact with the web 41, the offset toner on the cleaning roller 43 can be collected by the web 41 and the cleaning property of the cleaning roller 43 can always be kept high.
In FIG. 4, the offset toner collected from the surface of the pressure roller 32 is divided into a collected toner T1 by the web 41 and a collected toner T2 by the cleaning roller. Since the collected toner T1 is wound up toward the center of the web winding shaft 42 as shown in the drawing, a clean surface on the back side of the outer surface of the web winding shaft 42 appears.
When the collected toner T2 from the cleaning roller 43 adheres to the clean surface, the offset toner from the surface of the cleaning roller 43 is removed and the web 41 can be used effectively.

FIG. 5 is a cross-sectional view showing details of the cleaning roller of the cleaning unit of the fixing device according to the present invention. In FIG. 5, the cleaning roller 43 has a heat pipe 48 press-fitted into a hollow roller 47 made of iron or aluminum by heat expansion.
The inside of the heat pipe 48 is in a vacuum state, and when heated, a liquid such as water embedded in the pipe instantaneously moves in the pipe, so that the temperature is kept uniform in the axial direction. Protruding members 50a and 50b forming shaft ends are fixed to both ends of the hollow roller 47 by press-fitting, bonding or the like.
As described above, since the cleaning roller 43 has the heat pipe 48 therein, temperature unevenness in the axial direction is prevented, and the toner is further prevented from being melted.
The surface of the hollow roller 47 is covered with a heat-resistant elastic layer 49 such as silicone rubber or polyimide resin. The heat-resistant elastic layer 49 can obtain a cleaning effect utilizing a difference in releasability by selecting a material having a releasability lower than that of the surface layer of the pressure roller 32.

FIG. 6 is a schematic cross-sectional view of one end of the cleaning roller and the pressure roller in a contact state when a recording medium is present in the fixing nip. FIG. 7 is a schematic cross-sectional view of one end of the cleaning roller and the pressure roller in a separated state when no recording medium is present in the fixing nip.
In addition, the cleaning roller 43 passes the pressure roller 32 as shown in FIG. 6 while a recording medium (not shown) passes through a fixing nip between a heating roller and a pressure roller 32 (not shown). It is in the position where it abuts.
On the other hand, while the recording medium is not passing through the fixing nip, as shown in FIG. As a result, the temperature of the cleaning roller 43 is lowered during separation.
As described above, the cleaning roller 43 is brought into contact with the pressure roller 32 only when the recording medium passes through the fixing nip, and is separated when the recording medium is not passed. For this reason, the cleaning roller 43 is cooled during standby, and the temperature of the cleaning roller 43 at the start of paper feeding can be lowered to prevent toner from melting.

When the cleaning roller 43 is in contact with the pressure roller 32, the cleaning roller 43 is rotationally driven by the driving force transmitted from the pressure gear 51 to the cleaning roller drive gear 52 in FIG. Collect toner actively.
When the sheet is not fed, as shown in FIG. 7, it is separated from the pressure roller 32 and the drive from the pressure gear 51 is released. As a result, even when the pressure roller 32 performs idling by the cleaning operation during non-sheet passing, the torque to the fixing drive motor (not shown) can be kept low.
In this way, the cleaning roller 43 can keep the torque to the fixing drive motor low even if the idling rotation is performed by the cleaning operation during standby by releasing the rotation drive during non-sheet passing, and abnormal noise is generated. Can be prevented.
When the above-described fixing device according to the present invention is mounted as a fixing device of an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile, or a composite machine thereof, a good image forming apparatus that does not generate an abnormal image is provided. can do.

1 is a schematic front view showing an overall configuration of an image forming apparatus which is a copying machine equipped with a fixing device of the present invention. FIG. 3 is a schematic diagram illustrating a cleaning unit of the fixing device according to the present invention. FIG. 3 is a schematic diagram illustrating a state where a cleaning roller and a pressure roller of the cleaning unit in FIG. 2 are separated by a distance of ΔL. It is detail drawing which shows a cleaning part. FIG. 4 is a cross-sectional view illustrating details of a cleaning roller of a cleaning unit of the fixing device according to the present invention. FIG. 5 is a schematic cross-sectional view of one end of the cleaning roller and the pressure roller in a contact state when a recording medium is present in the fixing nip. FIG. 5 is a schematic cross-sectional view of one end of the cleaning roller and the pressure roller showing a separated state when no recording medium is present in the fixing nip.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Image forming apparatus, 2 Image forming apparatus main body, 3 Paper feeding apparatus, 10 Photosensitive unit, 10A Image carrier (photosensitive drum), 11 Fixing apparatus, 12 Developing apparatus, 17 Transfer belt, 30 Heating member (heating roller) , 32 Pressure member (pressure roller), 40 Cleaning section, 41 Cleaning member (web), 42 Web winding shaft, 43 Cleaning roller, 44 Web feed shaft, 45 Press roller, 46 Elastic pressure means (Pressure spring) ), 51 pressure gear, 52 cleaning roller drive gear, S recording medium

Claims (8)

  A fixing device comprising: a fixing unit that fixes a toner image on a recording medium while conveying the recording medium between a heating member and a pressure member; and a cleaning unit that removes toner attached to the pressure member. The cleaning member of the cleaning unit is constituted by a take-up type web, and the surface of the web that is in contact with the pressure member side is wound on the web take-up shaft with the surface facing inward. A fixing device, wherein a cleaning roller is brought into contact with a surface of the web wound by a take-up shaft.   The fixing device according to claim 1, wherein the cleaning roller abuts on the pressure member when the recording medium passes through the fixing nip, and is driven to rotate by being driven by the pressure member.   The fixing device according to claim 1, wherein the cleaning roller is separable from the pressure member when the recording medium is not passed through the fixing nip.   4. The fixing device according to claim 1, wherein the cleaning roller is constantly pressed against the surface of the web of the web winding shaft by an elastic pressing unit. 5.   5. The fixing device according to claim 1, wherein the cleaning roller includes a heat pipe inside and has a heat-resistant elastic layer on a surface thereof.   6. The fixing device according to claim 1, wherein the cleaning roller is in contact with the pressure member during sheet passing, and is separated from the pressure member during non-sheet passing.   7. The fixing device according to claim 1, wherein the cleaning roller is driven to rotate while the sheet is passing, and the rotation drive is released while the sheet is not passing. 8.   The electrostatic latent image formed on the image carrier is developed and visualized with toner, the visualized toner image is transferred onto a recording medium by a transfer device, and the toner image on the recording medium is transferred by heat and pressure. An image forming apparatus comprising: a fixing device according to claim 1, wherein the image forming device fixes the recording medium and sends the recording medium to a next process.

Images