JPH09269693A - Heat roller fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the contaminant such as toner from falling on a recording medium, on a path of the recording medium, or the like. SOLUTION: Accompanying the passing of a paper sheet 26 between a pressure roller 12 and a film 22 wound around a heat roller 10 and a supporting roller 18, a toner image is fixed on the paper sheet 26. If the toner is not entirely fixed on the paper sheet 26, the unfixed toner is not stuck on the heat roller 10, but on a surface of the film 22. The contaminant of such as the toner including the toner, is moved in accompany with the film 22 corresponding to traveling of the film 22. When the contaminant of the toner or the like reaches a blade 30, the contaminant such as the toner is scraped out by the blade 30 from the film 22. The blade 30 is arranged on the position so as to hold the film 22 in-between, with the supporting roller 18. On the position apart from the paper path 28, the contaminant such as the toner is removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat roller fixing device used in an electrophotographic image forming apparatus or the like to heat and fix a toner image on a recording medium.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus, for example, a laser beam containing information is scanned and exposed on a photosensitive drum, and an electrostatic latent image is formed on the photosensitive drum. The electrostatic latent image is visualized with toner and developed, and a toner image is formed on the photosensitive drum. On the other hand, the paper (recording medium) is sent from the paper feed tray to the photosensitive drum, and the toner image is transferred onto the paper. The sheet on which the toner image is transferred is sent from the photosensitive drum to the fixing unit, and the toner image on the sheet is fixed on the sheet. The sheet on which the toner image is fixed is sent to the discharge tray and accumulated there.

The fixing unit comprises a heat roller fixing device, and the heat roller fixing device comprises a heat roller and
This and a pressure roller forming a roller pair are provided. The heat roller is generally heated to around 200 ° C.
Further, the heat roller and the pressure roller can nip the paper with a strong pressure therebetween.
By passing the sheet between the heat roller and the pressure roller, the toner is soaked in the sheet by heat and pressure, and the toner image is fixed to the sheet.

In this case, not all the toner is fixed on the paper, but a part of the toner adheres to the surface of the heat roller and remains as dirt on the surface of the heat roller. When the toner is attached to the surface of the heat roller and the image formation is continued with the stain attached, the toner attached to the surface of the heat roller is attached as black spots or toner stains on the succeeding paper. This is a problem.

Therefore, in the prior art, Japanese Patent Laid-Open No. 2-247675
As disclosed in the publication, a cleaning pad, a blade, and the like are provided so as to face the surface of the heat roller. The dirt attached to the heat roller is removed by a blade or the like as the heat roller rotates. Certainly, it is effective at the beginning of running. However, the dirt gradually accumulates on the pad or the blade itself, and the dirt collectively collects and falls on the paper or on the paper path (paper passage). This is, on the contrary, a problem.

[0006]

SUMMARY OF THE INVENTION In consideration of the above facts, an object of the present invention is to provide a heat roller fixing device which prevents dirt such as toner from dropping on a recording medium or a passage of the recording medium. And

[0007]

In order to solve the above-mentioned problems, the heat roller fixing device of the present invention according to claim 1 is
In a heat roller fixing device for thermally fixing a toner image to a recording medium, a heat roller, a pressure roller forming a roller pair with the heat roller, a support roller provided separately from the heat roller, the heat roller and the support roller. An endless belt-shaped film member, which is wound between the pressure roller and the pressure roller to allow the recording medium to pass between the pressure roller and the film member, is provided so as to face the film member. A scraping member that scrapes off dirt such as toner attached to the film member from the film member,
It is characterized by a configuration including.

According to a second aspect of the present invention, in the heat roller fixing device of the first aspect, the dirt such as toner adhered to the film member is cooled and the dirt such as toner is cooled from the film member. It is characterized in that a cooling means for scraping is provided.

According to a third aspect of the present invention, there is provided the heat roller fixing device according to the first or second aspect, wherein the support roller is arranged on the recording medium passage exit side with respect to the heat roller. To do.

According to the above construction, the film member is wound around the support member and the heat roller, and in the heat roller, the film member is wound around and contacted with the outer periphery of the heat roller within a range according to the winding angle. The recording medium passes between the film member and the pressure roller as the heat roller rotates to move the film member and the pressure roller rotates. The heat roller heats the film member. The heated film member heats the recording medium. Further, the heat roller exerts a nip pressure on the recording medium between the heat roller and the pressure roller via the film member. As a result, the toner image is thermally fixed on the recording medium as the recording medium passes between the film member and the pressure roller.

If all the toner is not fixed on the recording medium, the unfixed toner is attached to the surface of the film member. Dirt such as toner that contains toner and is attached to the surface of the film member during fixing moves together with the film member as the film member runs. A member for scraping off dirt such as toner (for example, a pad or a blade)
When it reaches, the dirt such as toner is scraped off from the film member by the scraping member.

The film member runs away from the heat roller and returns to the heat roller via the support roller. Therefore, it is possible to dispose the scraping member at a position deviated from the passage of the recording medium, and remove dirt such as toner from the film member at a position deviated from the passage of the recording medium.

As a result, even if dirt such as toner removed from the film member does not accumulate on the scraping member and drops as it is due to scraping of the scraping member, dirt such as toner remains on the scraping member. Even if the stains are accumulated and the accumulated amount exceeds a certain amount and the stains fall as a lump, it is possible to avoid dropping onto the recording medium or the passage of the recording medium.

In this way, it is possible to prevent dirt such as toner from falling on the recording medium or the passage of the recording medium.

According to the second aspect of the present invention, according to the structure in which the dirt such as the toner attached to the surface of the film member is cooled and the dirt is scraped off, the viscosity of the dirt such as the toner is lowered and the dirt is scraped off. And the effect of removing stains such as toner is improved.

When the support roller is arranged on the passage outlet side of the recording medium with respect to the heat roller, the support roller is arranged on the passage inlet side opposite to the passage outlet side. Compared with the case, the recording medium is passed between the film member and the pressure roller from the position where the film member returns from the heat roller, returns to the heat roller through the support roller, and starts contact with the heat roller, and the fixing is performed. It is possible to increase the contact length of the film member with the heat roller up to the fixing position. The length of contact of the film member with the heat roller in order to compensate for the heat loss of the film member due to the film member separating from the heat roller and to secure the surface temperature of the film member at a predetermined temperature at the fixing position of the film member. It is effective to be able to take a long time. In particular, when cooling dirt such as toner adhered to the film member as in claim 2,
This is more effective because the heat loss of the film member is increased by the amount of cooling.

The scraping member can be arranged in parallel with the width direction of the film member (the axial direction of the heat roller) which is the direction perpendicular to the running direction of the film member, and the scraping member can be arranged. It is also possible to arrange the take-off member by inclining it from the width direction of the film member to the running direction side. By arranging the scraping member so as to incline from the width direction of the film member to the running direction side, dirt such as toner may cause the film member in the scraping member to travel along the disposing direction of the scraping member. The dirt that is scraped off by the scraping member is urged from the part located on the rear side in the direction toward the part located on the front side in the traveling direction of the film member in the scraping member to a certain place in the scraping member. Collected. When dirt such as toner collected and accumulated in a certain place falls as a lump, the drop position is limited to the applied range. Even if dirt such as toner falls to a position off the passage of the recording medium,
The fact that the drop position is limited to the applied range minimizes the influence of the drop on the part other than the passage of the recording medium. Further, it becomes easy to collect the dirt such as the dropped toner.

Further, it is possible to provide a receiving portion below the scraping member for receiving dirt such as toner falling from the scraping member. According to this, it is possible to prevent not only the passage of the recording medium but also other portions from falling.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of a heat roller fixing device according to the present invention will be described with reference to FIGS.

For example, although not shown, in an electrophotographic image forming apparatus, a laser beam containing information is scanned and exposed on a photosensitive drum, and an electrostatic latent image is formed on the photosensitive drum. The electrostatic latent image is visualized with toner and developed, and a toner image is formed on the photosensitive drum. Meanwhile, the paper (recording medium) is sent from the paper feed tray to the photosensitive drum,
The toner image is transferred onto the paper. The sheet on which the toner image is transferred is sent from the photosensitive drum to the fixing unit, and the toner image on the sheet is fixed on the sheet. The sheet on which the toner image is fixed is sent to the discharge tray and accumulated there.

The heat roller fixing device according to the present embodiment is provided in the fixing unit and includes a heat roller 10 and a pressure roller 12 forming a roller pair with the heat roller 10, as shown in FIG. Both roller shafts 14 and 16 of the heat roller 10 and the pressure roller 12 are parallel to each other, the heat roller 10 is located on the upper side, and the pressure roller 12 is located on the lower side.
0 and 12 face each other. Further, a support roller 18 is provided separately from the heat roller 10. Both roller shafts 20 and 14 of the support roller 18 and the heat roller 10 are parallel to each other, and a film (film member) 22 is wound between the support roller 18 and the heat roller 10. The film 22 has a flexible endless belt shape and travels with both rotations of the support roller 18 and the heat roller 10. The heat roller 10 is wound around the outer circumference of the heat roller 10 within a range according to the winding angle. And is in contact with the surface of the heat roller 10.

The heat roller 10 has a heater (heat roller heat source) 24 inside to heat the surface of the heat roller 10 and heat the film 22 wound around and in contact with the surface of the heat roller 10. Further, the heat roller 10 and the pressure roller 12 are urged in the contact direction.

As shown in FIG. 1, a sheet (recording medium) 26 having a toner image transferred onto the sheet is fed horizontally from the photosensitive drum to the fixing section in the direction of arrow A, from the right side in the figure. Come on. The heat roller 10 and the support roller 18 rotate in the direction of arrow B, the film 22 travels in the direction of arrow C, and the pressure roller 12 rotates in the direction of arrow D, which is opposite to the direction of rotation of the heat roller 10. Accordingly, the sheet 26 passes between the film 22 and the pressure roller 12. With this passage, the film 22 heats the paper 26, and
The heat roller 10 has the film 22 and the pressure roller 1
A nip pressure is applied to the paper 26 between the two and the heat and pressure to fix the toner to the paper, and the toner image is thermally fixed to the paper.

The paper 26 includes the film 22 and the pressure roller 12.
After passing between the sheet and the sheet, it is turned downward and sent to the discharge tray. A paper passage path is indicated by 28.

The material of the film 22 is preferably a material which is not easily deteriorated by heat in consideration of the fact that the film 22 is heated and receives pressure, and can be made of, for example, silicon.

The heat roller 10, the pressure roller 12, and the support roller 18 are all supported by a frame (not shown) of the image forming apparatus.

The supporting roller 18 is the heat roller 10.
On the other hand, it is arranged on the passage exit side (left side in FIG. 1) of the paper 26, and is arranged so as to incline the film 22 upward from the heat roller 10 toward the support roller 18. A blade (scraping member) 30 is provided so as to face the surface of the film 22. Blade 30
Is attached to the frame of the image forming apparatus and, as shown in FIG. 2, the width direction of the film 22 is parallel to the width direction of the film 22 (axial direction of the heat roller 10) which is a direction perpendicular to the running direction of the film 22. It is formed in a plate shape extending over a long dimension, and the tip edge portion along the longitudinal direction abuts and engages with the surface of the film 22 over the widthwise dimension of the film 22. The mounting position of the blade 30 is
The position is set apart from the paper path 28, and in the present embodiment, the position is set so as to face the support roller 18 with the film 22 interposed therebetween.

A shielding plate (receiving portion) 32 is provided below the blade 30. The shield plate 32 is fixed to the frame of the image forming apparatus, is interposed between the blade 30 and the components of the image forming apparatus located below the blade 30, and is bent into a hook shape when viewed from the axial direction of the heat roller 10. As shown in FIG. 3, the bottom portion 34 of the shielding plate 32 is horizontally provided over the longitudinal dimension of the blade 30.

According to the above construction, the heat roller 10 rotates and the film 22 runs, and the pressure roller 1
As the sheet 2 rotates, the sheet 26 passes between the film 22 and the pressure roller 12. The heat roller 10 heats the film 22. The heated film 22 heats the paper. Further, the heat roller 10 exerts a nip pressure on the paper 26 with the pressure roller 12 via the film 22. As a result, the toner image is thermally fixed on the paper 26 as the paper 26 passes between the film 22 and the pressure roller 12.

Here, when all the toner is not fixed on the paper 26, the unfixed toner is attached to the surface of the film 22 instead of the heat roller 10. Dirt such as toner that contains toner and is attached to the surface of the film 22 during fixing moves together with the film 22 as the film 22 travels. Dirt such as toner will be removed by blade 30
When reaching, the dirt such as toner is scraped off from the film 22 by the blade 30.

The film 22 runs away from the heat roller 10 and returns to the heat roller 10 via the support roller 18. Therefore, like the present embodiment in which the blade 30 is arranged at a position where the film 22 is sandwiched between the supporting roller 18 and the support roller 18, the blade 30 is arranged at a position apart from the paper path 28 and apart from the paper path 28. However, dirt such as toner can be removed from the film 22 at a position off the paper path 28.

Therefore, dirt such as toner removed from the film 22 is not accumulated on the blade 30 and the blade 30
On the paper or the paper path 28, even if it is dropped as it is scraped, or if dirt such as toner is accumulated on the blade 30 and the accumulated amount exceeds a certain amount and the dirt falls as a lump. To fall is avoided. 3 fallen objects in Figure 1
Shown by 6.

In this way, dirt such as toner can be prevented from falling on the paper 22 and the paper path 28.

In the present embodiment, the mounting position of the blade 30 is such that the support roller 18 is sandwiched by the film 22.
However, the position is not limited to such a position, and the above-described effects can be exhibited if the position is a position deviated from the paper path 28. However, the blade 30 is the film 22
By being positioned so as to face the supporting roller 18 with the nip interposed therebetween, or by being positioned in the vicinity thereof, it is possible to secure sufficient contact with the film 22 of the blade 30 for scraping off dirt such as toner. it can.

The scraping member is not limited to the blade 30 and may be a pad or the like as long as it can scrape off dirt such as toner from the surface of the film 22. The blade 30 can be made of rubber or the like, and the pad can be made of felt or the like.

Further, the supporting roller 18 is the heat roller 10.
On the other hand, since it is arranged on the passage exit side of the paper 22,
As shown in FIG. 1, the film 22 is separated from the heat roller 10 as compared with the case where the support roller 18 is arranged on the side of the passage entrance opposite to the side of the passage exit.
The heat roller for the film 22 from a position 36 where the paper 22 is returned to the heat roller 10 to start contact with the heat roller 10 to a fixing position 38 where the paper 22 is fixed between the film 22 and the pressure roller 12 for fixing. The contact length with 10 can be made long. In order to compensate for the heat loss of the film 22 caused by the film 22 separating from the heat roller 10 and to secure the surface temperature of the film 22 at a predetermined temperature at the fixing position 38 of the film 22, the film 2
It is effective that the contact length of the second heat roller 10 can be made long. That is, the film 22 once separated from the heat roller 10 is smoothly reheated.

When dirt such as toner scraped off by the blade 30 falls, the dirt is removed by the shield plate 3.
It is received by the bottom 34 of the two. Therefore, the drop of dirt such as toner is prevented even in other parts of the image forming apparatus other than the paper path 28, and the parts are prevented from being smeared in the other parts due to the drop.

As for the shield plate 32, as shown in FIG. 4, the bottom portion 34 of the shield plate 34 can be inclined obliquely downward from the horizontal direction along the longitudinal direction of the blade 30. According to this, the dirt such as toner dropped on the bottom portion 34 is made to slide along the bottom portion 34 to the lower portion (the right portion in FIG. 4) in the bottom portion 34, and collected in one place. To be It becomes easy to collect stains such as toner, and maintainability is improved. It is also possible to form the receiving part with a detachable collection box,
According to this, it becomes possible to collect the dirt only by removing the collection box, and the maintainability is further improved.

Next, a second embodiment will be described with reference to FIG. In the present embodiment, the heat roller 200
The outer circumferences of the support roller 202 and the support roller 202 are formed in a gear shape (repetitive uneven shape). According to this, even when the surface friction coefficient of the film 22 is low, it is possible to counter the slip between the film 22 and the heat roller 200 and the support roller 202.

The above structure can be applied to the third to fifth embodiments described later. Other configurations, functions and effects are similar to those of the first embodiment.

Next, a third embodiment will be described with reference to FIG. In the present embodiment, the blade 30 is arranged such that its longitudinal direction is inclined with respect to the width direction of the film 22 in the traveling direction. According to this, stains such as toner are transferred from the portion of the blade 30 located on the rear side in the running direction of the film 22 (the upper portion in FIG. 6) along the longitudinal direction of the blade 30 to the film in the blade 30. The stains such as toner scraped off by the blade 30 are urged toward the portion of the blade 22 located on the front side in the traveling direction (the portion on the lower side in FIG. 6) and are collected in a certain place in the blade 30. When dirt such as toner collected and accumulated in a certain place falls as a lump, the drop position is limited to the applied range. When the shield plate 32 is provided below the blade 30, dirt such as toner can be collected at a fixed location on the shield plate 32, and dirt such as toner can be easily collected. In addition, shielding plate 3
When No. 2 is not provided, the fact that the position where the dirt such as toner falls is limited to the applied range minimizes the influence of the fall of the dirt onto the portion other than the paper path 28. . Further, it becomes easy to collect the dirt such as the dropped toner.

The above structure can be applied to the fourth and fifth embodiments described later. Other configurations, functions and effects are similar to those of the first embodiment.

Next, a fourth embodiment will be described with reference to FIG. In the present embodiment, the blade 3 of the film 22
A cooling device (cooling means) 400 is provided below the portion corresponding to the front side of 0. The cooling device is attached to the frame of the image forming apparatus. Contamination such as toner adhered to the film 22 at the time of fixing has a high viscosity in a sticky state like an adhesive. The cooling device 400 is
Before scraping off dirt such as toner with the blade 30, the dirt such as toner attached to the film 22 is cooled so that dirt such as toner is easily scraped off when scraping off dirt such as toner with the blade 30. This improves the effect of removing dirt such as toner.

As the cooling device 400, a general one using heat of vaporization or one using a Peltier element can be used, and is appropriately selected in consideration of space and cost. For example, a fan, a cooler, an air conditioner or the like can be used.

When the dirt such as the toner attached to the film 22 is cooled, the heat loss of the film 22 increases by the amount of the cooling, so that the support is performed as described in the first embodiment. With the configuration in which the roller 18 is arranged on the passage exit side of the paper 22 with respect to the heat roller 10,
The contact length of the film 22 with the heat roller 10 from a position 36 where the film 22 starts to contact the heat roller 10 to a fixing position 38 where the paper 22 is passed between the film 22 and the pressure roller 12 to perform fixing. It is even more effective that the length can be taken longer.

The above configuration is applicable to the fifth embodiment described later. Other configurations, functions and effects are similar to those of the first embodiment.

Next, a fifth embodiment will be described with reference to FIG. In this embodiment, a plurality of scraping members are provided. As shown in FIG. 8, the pad 500 as a scraping member is located at a position facing the support roller 18, and the two blades 30 are provided near the support roller 18 on the rear side of the pad 500 in the traveling direction of the film 22. Located in close proximity.
Both blades 30 are separated from each other along the traveling direction of the film 22.

By thus providing a plurality of scraping members, the effect of removing dirt such as toner is improved.

When the scraping member is directly brought into contact with the outer circumference of the heat roller to scrape off the dirt such as toner adhering to the surface of the heat roller as in the conventional case, the scraping member is used around the circumference of the heat roller. It is difficult in terms of space to provide a plurality along the direction. When the scraping member is brought into contact with the surface of the film 22 and dirt such as toner adhered to the surface of the film 22 is scraped off by the scraping member as in the present embodiment, it faces the surface of the film 22. By providing a plurality of scraping members along the running direction, a wide space for installing the blade is secured along the running direction of the film 22. Effective use of space is achieved.

Other constitutions and effects are similar to those of the first embodiment.

[0051]

In the heat roller fixing device of the present invention, dirt such as toner can be prevented from falling on the recording medium or the passage of the recording medium.

[Brief description of drawings]

FIG. 1 is a front view showing a heat roller fixing device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing the heat roller fixing device of FIG. 1 as it is looked up while omitting a receiving portion and a pressure roller.

FIG. 3 is a sectional view taken along line 3-3 of FIG. 1;

FIG. 4 is a diagram corresponding to FIG. 3 showing a modified example of the shielding unit.

FIG. 5 is a front view showing a heat roller fixing device according to a second embodiment.

FIG. 6 is a diagram corresponding to FIG. 2 showing a third embodiment.

FIG. 7 is a front view showing a heat roller fixing device according to a fourth embodiment.

FIG. 8 is a front view showing a heat roller fixing device according to a fifth embodiment.

[Explanation of symbols]

 10 Heat Roller 12 Pressure Roller 18 Support Roller 22 Film (Film Member) 26 Paper (Recording Medium) 28 Paper Path (Passing Path of Recording Medium) 30 Blade (Scraping Member) 200 Heat Roller 202 Support Roller 400 Cooling Device (Cooling Unit) ) 500 pads (scraping member)

Claims (3)

[Claims] 1. A heat roller fixing device for thermally fixing a toner image to a recording medium, a heat roller, a pressure roller forming a roller pair with the heat roller, a support roller provided separately from the heat roller, An endless belt-shaped film member which is wound around a heat roller and a support roller and is movably provided, and which allows a recording medium to pass between the pressure roller and the pressure roller for heat fixing, and a film member facing the film member. A heat roller fixing device comprising: a scraping member that is provided to scrape off dirt such as toner adhered to the film member by heat fixing from the film member. 2. A cooling means for cooling dirt such as toner adhered to the film member and scraping dirt such as toner from the film member in a cooled state. The heat roller fixing device described. 3. The heat roller fixing device according to claim 1, wherein the support roller is arranged on a passage exit side of the recording medium with respect to the heat roller.