JP2886764B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming an image on a recording material carried on a recording material carrier, for example, an electrophotographic image forming apparatus, particularly an electrophotographic photosensitive member. A color electrophotographic copying apparatus that forms a plurality of toner images of different colors on a photosensitive drum, and sequentially superimposes and transfers the toner images onto the same recording material carried on a recording material carrier to obtain a color image Can be suitably applied.

[0002]

2. Description of the Related Art Conventionally, a color image is formed by forming a plurality of image forming sections, forming toner images of different colors in each of the image forming sections, and sequentially superposing and transferring the toner images on the same recording material. There have been proposed various color image forming apparatuses for obtaining a color image. Among them, a color copying apparatus based on a multi-color electrophotographic system is widely used.

An example of such a color electrophotographic copying apparatus will be briefly described with reference to FIG. As shown in FIG.
The color electrophotographic copying apparatus has a conveyor belt 108 suspended between a pair of rollers 117a and 117b in an apparatus main body 110 and driven in a direction indicated by an arrow c by a driving source (not shown).
And four image forming units Pa, Pb, Pc, and Pd are disposed above the conveyor belt 108. Since the respective image forming units have the same configuration, the configuration will be schematically described below taking the first color image forming unit Pa as an example.

In the image forming section Pa, the above-described conveyor belt 1 is provided.
08, a cylindrical photosensitive drum 101a that rotates in the direction of arrow A is disposed, and the photosensitive layer on the surface of the photosensitive drum 101a is uniformly charged by the primary charger 115a. Light image 116 of the yellow component
is exposed to form an electrostatic latent image on the photosensitive drum 101a. The latent image is moved by the rotation of the photosensitive drum 101a and reaches the position of the developing device 103a.
The latent image is developed with the yellow toner supplied from 03a, and the latent image is visualized as a yellow toner image.

The above yellow toner image is transferred to the photosensitive drum 1
With the rotation of 01a, it reaches the transfer site where the transfer charging member 104a is arranged. In accordance with this, the conveyance path 11
From 2, a recording material (not shown) is conveyed to the transfer site, and a transfer bias is applied to the transfer charging member 104 a, whereby the yellow toner image is transferred from the photosensitive drum 101 a onto the recording material.

Thereafter, the residual toner remaining on the photosensitive drum 101a is removed by the cleaning device 105a, and the photosensitive drum 101a is ready for the next image forming step. on the other hand,
The recording material onto which the yellow toner image has been transferred is transport belt 1
08, the process proceeds to the next second color image forming section Pb.

The image forming section Pb for the second color has the same configuration as the image forming section Pa for the first color, and forms a latent image on the photosensitive drum and a latent image with magenta toner in the same manner as described above. The image is developed, and the obtained magenta toner image is transferred onto the recording material at the transfer portion so as to overlap the yellow toner image. Similarly, in the image forming sections Pc and Pd, a cyan toner image and a black toner image are formed, sequentially transferred and superimposed on a recording material, and a color image in which four color toner images are superimposed on the recording material is formed. can get.

The recording material onto which the four color toner images have been transferred is separated from the conveyor belt 108 and sent to a fixing device 107 having a pair of fixing roller and pressure roller, and is usually heated to a predetermined temperature. The toner image of each color is fixed and fixed to the recording material by being pressed and heated at the nip portion of the roller, thereby forming a full-color permanent image. It is discharged outside.

By the way, as a characteristic of the color toner, good melting property and color mixing property when heated by a fixing device are required. If the melting and color mixing properties are poor, the air gap between the toner particles increases, and the original color tone of the toner dye is lost due to scattering of light at the interface with air,
This is because the lower layer toner is concealed by the upper layer toner in the portion where the toner overlaps, and the color reproducibility is reduced. To satisfy these melting properties and color mixing properties, a so-called sharp melt toner having a low softening point and a low melting viscosity is used. By using such a sharp-melting toner, color reproducibility can be enhanced and a color copy faithful to a document can be obtained.

[0010] However, the sharp melt toner has a disadvantage that it tends to be offset to the fixing roller of the fixing device because of its high affinity. In the fixing device, pressure is applied in addition to heating. The toner having a high affinity tends to be transferred to and adhered to the fixing roller by the heating and pressurization. When the toner adheres to the fixing roller, the toner is transferred to the next recording material or solidified on the fixing roller,
Any of these causes image defects.

Therefore, in order to prevent the occurrence of these image defects, a release agent is used, and before the fixing of the toner image on the recording material by the fixing device, the separation of the liquid such as oil onto the fixing roller is performed. The mold is applied. As a result, when the toner image is heated and pressed, the fixing roller does not directly contact the toner image on the recording material but comes into contact with the toner image via the release agent, and the toner is transferred to the fixing roller side. To effectively prevent adhesion.

After the toner image is fixed, the release agent remaining on the fixing roller is wiped off by, for example, a cleaning device provided with a nonwoven fabric.

On the other hand, the transport belt 10 from which the recording material is separated
In 8, the charged charge received at the time of transfer is removed by the operation of the inner static eliminator 113 and the outer static eliminator 114. Further, the fogging toner and the scattered toner adhered to the surface of the transport belt 108 are cleaned by the fur brush 111 and the backup brush 120 of the transport belt cleaning means provided downstream of the neutralizers 113 and 114 in the traveling direction of the transport belt 108. Alternatively, dust such as paper dust is removed.

The toner and dust scraped off by the fur brush 111 are sucked and collected by the suction member 112. Conveyor belt 10 whose surface is cleaned
8 is prepared for the next image formation.

[0015]

As described above, a releasing agent is used for the fixing roller of the fixing device 7, but the toner is transferred from the toner image on the recording material to be fixed to the fixing roller. However, when copying is performed on both sides of the recording material, the release agent attached to the recording material from the fixing roller is transferred to the conveyor belt, and further from the conveyor belt to the photosensitive drum, causing a new problem that causes image defects. Occurs.

That is, in the case of double-sided copying, if the first surface on which an image is formed at the beginning of the recording material is the first surface and the second surface on which the image is formed next is the second surface, recording is performed by the first image formation. The release agent transfers to the first surface of the material. The transfer of the release agent may be performed without any problem in the case of single-sided copying in which no image is formed on the second side. However, in the case of double-sided copying, the first side of the recording material is used to form an image on the second side. Since it is adsorbed and supported on the conveyor belt side, the release agent on the first surface is transferred to the conveyor belt surface. Thereafter, when the transfer of the toner image onto the second surface is completed and the recording material is separated from the transport belt for fixing, the release agent on the surface of the transport belt contacts the photosensitive drum. Transfer to and adhere to the surface.

When the release agent is transferred and adhered to the photosensitive drum in this way, the release agent cannot be sufficiently removed by a photosensitive drum cleaning device which originally aims to remove residual toner on the photosensitive drum. For this reason, the residual toner on the photosensitive drum gets on the release agent such as oil,
The releasability of the residual toner from the photosensitive drum deteriorates, and the residual toner cannot be sufficiently removed by the cleaning device. Furthermore, if the release agent is attached on the photosensitive drum,
In addition to the residual toner, the toner at the time of development easily adheres to a portion outside the image forming area (especially, in the case of flying toner such as jumping development, extra toner adheres more).

As described above, the residual toner and the toner during development due to the release agent on the photosensitive drum originally
The toner adheres to the area where the toner should not adhere, and these toners are transferred at the time of the subsequent image formation, and the copy image obtained thereafter becomes dirty.

In order to prevent such a problem from occurring, it is sufficient that the cleaning agent such as the fur brush 111 described above can clean the release agent attached to the surface of the conveyor belt 108. Was ineffective against the release agent, and the release agent could hardly be removed.

An object of the present invention is to provide a cleaning means for a recording material conveying belt, which is capable of satisfactorily cleaning not only toner adhering to the conveying belt but also a releasing agent, and image contamination due to the releasing agent adhering to the conveying belt. It is an object of the present invention to provide an image forming apparatus capable of obtaining a high-quality image by preventing image formation.

[0021]

The above object is achieved by an image forming apparatus according to the present invention. In summary, the present invention is directed to an image carrier on which a toner image is formed, a transport belt that transports the recording material to the image carrier by rotating while supporting the recording material, and an image bearing member on the transported recording material. A transfer charging unit that transfers the toner image formed on the carrier, and a recording material that transfers the toner image and is separated from the conveyance belt is heated and pressed by a fixing member coated with a release agent to form a toner image. A fixing unit for fixing the recording material, and after fixing the toner image, the toner image is further transferred upside down to the remaining surface of the recording material carried on the transport belt, and the recording material is separated. An image forming apparatus provided with a cleaning unit for cleaning the surface of the transport belt, wherein the cleaning unit includes a cleaning unit for cleaning toner adhered to the transport belt; and a release agent attached to the transport belt. An image forming apparatus, characterized in that it comprises at least two cleaning cleaning means. According to the invention, the cleaning means for cleaning the release agent is constituted by using a nonwoven web as a cleaning member. The recording material after the toner image is fixed can be turned upside down by re-sending means and re-sent to the transport belt to be carried.

[0022]

【Example】

Embodiment 1 An embodiment of an image forming apparatus according to the present invention will be described with reference to FIG. As shown in FIG. 1, this embodiment is embodied in a color electrophotographic copying apparatus similar to that described with reference to FIG.

In this embodiment, in the image forming apparatus, image forming sections Pa, Pb, Pc and Pd are arranged in a main body 10 of the apparatus, and a driving roller 11, a driven roller 12, and a driving roller 12 are arranged below these image forming sections Pa to Pd. A recording material conveying means including a conveying belt 8 wound around 13 is provided, and the conveying belt 8 is rotated at a speed of 100 mm / sec in the direction of the arrow. In this embodiment, an endless sheet made of a dielectric polycarbonate resin film was used as the transport belt 8.

As the material used for the conveyor belt 8, in addition to the above materials, a resin obtained by modifying a polycarbonate resin with a silicone resin, or by dispersing conductive particles such as carbon to have a resistance of, for example, 10 ¹² to 10 ¹⁵ Ω · cm. It is possible to use such a reduced one, and these are more preferable. Further, a polyurethane resin, a polyester resin, a nylon resin, a polyvinylidene fluoride (PVdF) resin, or the like can be used.

In this embodiment, the transport belt 8 has a thickness of 15 mm.
It is formed with a thickness of 0 μm and a width of 334 mm. During the rotation, the transport belt 8 is always deviated in one of the width directions perpendicular to the traveling direction, so that an accident such as detachment from the driving roller 11 and the driven rollers 12 and 13 does not occur. , 12 and 13 are provided near the center in the width direction.

A registration roller 13 is disposed on the right side of the conveyor belt 8 in the drawing. The image forming units Pa, Pb, Pc and Pd arranged above the conveyor belt 8 have photosensitive drums 1a, 1b, 1c and 1d.
a, 1b, 1c, 1d, chargers 15a, 15
b, 15c, and 15d are provided.
b, 3c and 3d are provided.

A single common laser beam scanner 16 is arranged above the photosensitive drums 1a, 1b, 1c and 1d. The laser beam scanner 16 is composed of a semiconductor laser, a polygon mirror, an fθ lens, etc., receives an input of an electric digital image signal, and modulates a laser beam corresponding to the input signal with a charger 15a, 15b, 15c, 15d.
The developing units 3a, 3b, 3c, and 3d are configured to scan in the generatrix direction of the photosensitive drums 1a, 1b, 1c, and 1d to expose the photosensitive drums 1a to 1d.

When an image formation start signal is input to the image forming apparatus, the photosensitive drum 1a starts rotating in the direction of the arrow, and is uniformly charged by the charger 15a. The laser beam modulated by the image signal corresponding to the yellow component is exposed, and a latent image of the yellow component is formed on the photosensitive drum 1a. The latent image is developed by supplying the yellow toner by the developing device 3a, and is visualized as a yellow toner image on the photosensitive drum 1a.

On the other hand, the recording material (paper) is taken out of the recording material cassette 60 by the pickup roller 9 and sent to the registration roller 13. The recording material is a registration roller 1.
After being stopped once at 3, the toner is supplied from the registration roller 13 onto the transport belt 8 which has already started to rotate at a timing with the yellow toner image formed on the photosensitive drum 1a. The recording material supplied on the conveyor belt 8 is a transfer section where the transfer charging member 4a of the image forming section Pa is disposed.
The transfer member 8a receives the transfer charge from the back side of the conveyor belt 8 to transfer the yellow toner image on the photosensitive drum 1a.

Similar image forming steps are performed for image forming sections Pb, Pc and Pd for magenta, cyan and black, and a yellow toner image, a magenta toner image, a cyan toner image and a black toner image are formed on recording material 8 from below. Are superimposed and transferred to obtain a color image.

The recording material on which the transfer of the toner image has been completed is placed almost directly above the roller 11 at the left end of the conveyor belt 8 by the separation charger 6.
While being subjected to AC static elimination by 1, it is separated from the conveyor belt 8 and sent to the fixing device 7 via the pre-fixing conveyor 14. In the fixing device 7, the toner image is heated and pressed by a pair of rollers to be fixed, and the color of the toner image is mixed and fixed to the recording material to form a full-color permanent image.

Each photosensitive drum 1a, 1b,
1c and 1d denote the respective cleaning devices 5a and 5d.
Residual toner is removed by b, 5c, and 5d to prepare for the subsequent image formation.

When the above-described fixing of the toner image is completed, the image formation is terminated as it is in the case of one-sided copying, and the sheet is discharged to the outside of the copying apparatus main body 10. In the case of double-sided copying, the recording material is turned upside down. The remaining surface (second surface) opposite to the surface (first surface) on which the image has been formed after being re-sent to the conveyor belt 8
The image is formed again.

The recording material is used to form an image on the second surface.
The recording material is temporarily stored in the stocker 56 through the guides 32a and 32b of the re-feeding means, and then passes through the guide 32b from the stocker 56 in reverse, enters the guide 32c with the rear end first and upside down to enter the guide 32c. The standby cassette 58 is entered. Thereafter, the recording material is supplied onto the conveyor belt 8 via the registration roller 13, and an image is formed on the second surface in the same manner as on the first surface. The recording material on which the color image is formed on the second surface is separated from the transport belt 8 and is fixed by the fixing device 7 and then discharged out of the copying apparatus main body 10 as a double-sided copy.

An inner static eliminator 62 and an outer static eliminator 63 are provided at a lower orbital position just before the downstream end of the transport belt 8 with the transport belt 8 interposed therebetween, and the charged charges received at the time of transfer are removed. The transport belt 8 from which the charged charges have been removed is then cleaned by a cleaning unit to remove toner, dust, and a release agent attached to the transport belt 8.

According to the present invention, in order to remove the toner and the release agent satisfactorily, the cleaning means of the transport belt 8 is provided separately for the toner and the release agent.

In this embodiment, the fur brush 23 is used as a toner cleaning means. Fur brush 23
Is installed downstream of the neutralizers 62 and 63 in the traveling direction of the transport belt 108, and the transport belt 1 by the fur brush 23 is
08, the toner and dust adhering to the surface of the conveyor belt 108 are removed. The toner and the like scraped off by the fur brush 23 are collected by a collecting device 24 having a suction fan.

The release agent cleaning means was provided with a nonwoven fabric cleaning web 19 as a cleaning member. The release agent cleaning means is provided downstream of the fur brush 23, and winds the cleaning web 19 around one of the pair of rollers 17, 18, for example, the roller 18, and winds this around the roller 17. Roller 17,
Between the cleaning belt 19 and the transport belt 8
A pressing roller 22 for pressing the cleaning web 19 against the conveying belt 8 is provided on the back side (inside) of the conveying belt 8.

The cleaning web 19 has at least a surface (cleaning surface) contacting the conveyor belt 8 with a thickness of 10 μm or less, at least 70% and an average thickness of 1 μm.
With a fiber of 0 μm or less, the density is 0.05 to 0.80.
g / cm ³ , preferably 0.10 to 0.50 g / cm ³
Is formed. The average distance between the individual fibers forming the cleaning web is preferably equal to or less than the average particle size of the toner particles used for image formation.

The fibers of the cleaning web 19 include
Fibers such as polypropylene, rayon, acrylic, nylon, polyester and vinylon, and mixtures of these fibers are preferred.

The cleaning web 19 is preferably used in which a new surface is updated at an appropriate interval, for example, a usage mode in which a predetermined amount is wound up every predetermined number of image formations. The cleaning web 19 was wound around the roller 17 by a means (not shown) by 5 mm for each formed sheet.

The pressing roller 22 is provided on a metal core such as SUS.
It is a rubber roller or the like having a non-foamed or foamable rubber layer. The backup roller 21 is also formed of a similar rubber roller or the like.

In the above description, the positional relationship between the fur brush 23 and the cleaning web 19 is such that if toner adheres to the surface of the web 19, the performance of the web 19 to remove the release agent is significantly reduced. Furthermore, as in the present embodiment, it is preferable that the fur brush 23 is arranged first and the cleaning web 19 is arranged later.

The image forming apparatus of this embodiment is configured as described above, and cleans toner and dust adhering on the conveyor belt 8 with the fur brush 23 and then removes the release agent adhering on the conveyor belt 8 with a nonwoven fabric. Since the cleaning is performed using the cleaning web 19 made of the toner, not only the toner and dust adhering to the conveyor belt 8 but also the release agent adhering during the double-sided image formation can be satisfactorily removed. Therefore, it is possible to prevent an image defect such that the release agent is re-adhered from the conveyor belt 8 to the photosensitive drums 1a to 1d to cause image stains.

The pressing roller 2 of the cleaning web 19
2 and the backup roller 21 are made conductive and a bias is applied thereto, the adhesion of the cleaning web 9 to the transport belt 8 is increased, and the release agent removing performance by the web 8 is improved. was gotten.

Embodiment 2 FIG. 2 is an overall configuration diagram showing another embodiment of the image forming apparatus of the present invention. As shown in FIG. 2, in the present embodiment, FIG.
Is characterized in that a cleaning blade 25 is used in place of the fur brush 23 as the toner cleaning means for the transport belt 8. Other configurations of the present embodiment are basically the same as those of the first embodiment. In FIG. 2, the same reference numerals as those shown in FIG. 1 denote the same members.

The cleaning blade 25 is made of polyurethane rubber and has a JIS rubber hardness of about 65 degrees. Further, the contact position of the cleaning blade 25 with the conveyance belt 8 is substantially immediately below the drive roller 11, the contact angle of the blade 25 with the conveyance belt 8 is about 20 degrees, and the intrusion amount is 1.5 to 2.0 mm. It was adjusted to become.

In this embodiment, too, the toner and dust adhering to the transport belt 8 are removed by cleaning with the cleaning blade 25, and the transport belt 8 from which the toner and the like have been removed is cleaned by the cleaning web 19, so that the transport belt 8 is removed. Since the release agent attached to the top is removed,
Not only toner and dust adhering to the conveyor belt 8 but also a releasing agent adhering during double-sided image formation can be satisfactorily removed. Therefore, it is possible to prevent an image defect such that the release agent is re-adhered from the conveyor belt 8 to the photosensitive drums 1a to 1d to cause image stains.

Also in this embodiment, since the cleaning means for the toner and the cleaning means for the release agent are separately provided, not only the toner and dust adhering on the transport belt 8 but also the toner adhering during the double-sided image formation. The release agent can be removed satisfactorily, and image stains due to the release agent can be prevented.

In the above description, the cleaning means for the toner and the cleaning agent for the release agent are provided separately as the cleaning means for the transport belt 8, but, for example, both surfaces of the cleaning web 19 shown in FIG. 1 are formed on the cleaning surface. A surface of the cleaning web 19 is brought into contact with the conveyor belt 8 by the pressing roller 22 and used for removing the release agent;
If the other surface is used for removing toner by contacting the other surface with the transport belt 8 by the roller 17 (on the upstream side of the pressing roller 22) around which the cleaning web 19 is wound, it is necessary to separately provide a toner cleaning unit. In addition, the size of the cleaning device can be reduced, which is more preferable.

[0051]

As described above, in the image forming apparatus of the present invention, the toner cleaning agent and the release agent are separately provided as cleaning means for the recording material conveying belt. In addition, it is possible to satisfactorily remove the release agent adhered at the time of double-sided image formation, prevent image stains due to the release agent or the like adhered to the transport belt, and obtain a high-quality image.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of an image forming apparatus of the present invention.

FIG. 2 is an overall configuration diagram showing another embodiment of the image forming apparatus of the present invention.

FIG. 3 is an overall configuration diagram showing a conventional image forming apparatus.

[Explanation of symbols]

 1a to 1d Photosensitive Drum 4a to 4d Transfer Charging Member 7 Fixing Device 8 Conveying Belt 11 Drive Roller 19 Cleaning Web 21 Backup Roller 22 Pressing Roller 23 Fur Brush 25 Cleaning Blade

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B65H 5/00 G03G 15/00 G03G 13/01 G03G 15/01

Claims (3)

(57) [Claims] An image bearing member on which a toner image is formed, a transport belt that carries the recording material and conveys the recording material to the image carrier by rotating, and an image carrier on the transported recording material Transfer and charging means for transferring the toner image formed on the recording material, and a recording material which transfers the toner image and is separated from the conveyance belt, is heated and pressed by a fixing member coated with a release agent, and the toner image is transferred to the recording material. After fixing the toner image, the toner image is further transferred upside down to further transfer the toner image to the remaining surface of the recording material carried on the conveyance belt, and after the recording material is separated, In the image forming apparatus provided with a cleaning unit for cleaning a surface of the conveyor belt, the cleaning unit includes a cleaning unit for cleaning toner adhered to the conveyor belt, and a cleaning unit for cleaning a release agent adhered to the conveyor belt. An image forming apparatus comprising at least two cleaning units. 2. The image forming apparatus according to claim 1, wherein the cleaning means for cleaning the release agent is configured using a nonwoven web as a cleaning member. 3. The recording material after fixing the toner image,
The image forming apparatus according to claim 1, wherein the image forming apparatus is turned upside down by a re-sending unit and re-sent to and carried by the conveyance belt.