JPH1152641A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device in which fuzz and paper powder on a recording sheet are eliminated from parts where they are most likely to stick, and in which turbulence of a formed image can be prevented. SOLUTION: In an image forming device comprising a feed roller 2 to feed a recording sheet P from a feed cassette 5 on which the recording sheet P is stacked, a transfer roller 16 coming in contact with a latent image carrier to transfer an image formed on the latent image carrier onto the recording sheet P, and a carrying passage 3 to carry the recording sheet P in such a way that a contact surface of feed roller 2 of the recording sheet P comes in contact with the transfer roller 16, a sheet cleaning roller 19 is disposed just before the transfer roller 16 and on the transfer roller side in the carrying passage 3, and a roller cleaning means 20 is provided on the sheet cleaning roller 19.

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, and more particularly to an electrophotographic image forming apparatus such as a laser printer or a copying machine for transferring an image on a photosensitive drum to a recording sheet to form an image on recording paper. is there.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus forms an electrostatic latent image on a photosensitive drum, visualizes the latent image with developing means, and transfers the visualized image from the photosensitive drum onto a recording sheet by transfer means. The image is formed by transferring and fixing the image on the recording sheet by a fixing unit.

In general, a photosensitive drum is formed by forming a photosensitive layer on a conductive substrate such as aluminum. The photosensitive layer has high resistance in a dark place, but has a property of decreasing resistance when exposed to light. . The surface of the photosensitive drum is uniformly charged to a predetermined potential by a charging means such as a corona charger or a charging roller, and then irradiated with light corresponding to image information, thereby forming an electrostatic latent image on the photosensitive drum. Is formed. The electrostatic line image is developed with toner, and the visualized image is transferred to a recording sheet.

[0005] 50 to hundreds of recording sheets are stored in a feeding cassette, and are sent out by a feeding roller provided above the feeding cassette. In recent years, assuming that the entire apparatus can be miniaturized, a feeding cassette is arranged at the lower portion of the apparatus main body, and the sheet surface of the recording sheet is reversed, that is, the surface where the feeding roller is touched comes to the transfer roller side. The transport path is formed as described above.

[0005]

However, in the above-described image forming apparatus, the recording sheet is rubbed when the feeding roller rubs the recording sheet when the recording sheet is sent out, and the fluff or paper dust is generated. Adheres to the transfer roller and eventually adheres to the photosensitive drum. The attached fluff or paper dust disturbs the latent image on the photosensitive drum as a low-resistance substance, particularly in an environment of high humidity, and as a result, the image is disturbed.

[0006] Similarly, in the transport path in which the recording sheet is not reversed, the surface of the recording sheet rubbed by the feed roller directly contacts the photosensitive drum. Accordingly, paper dust and the like adhere to the photosensitive drum, and the image is disturbed.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus capable of removing fluff and paper dust from a portion of a recording sheet where the amount of fluff and paper dust is the largest, thereby preventing disturbance of a formed image.

[0008]

In order to achieve the above object, a typical configuration of an image forming apparatus according to the present application includes a feeding cassette on which recording sheets are stacked, and sending the recording sheets from the feeding cassette. An image forming apparatus, comprising: a feeding roller that performs, a latent image carrier, and a transfer roller that abuts on the latent image carrier and transfers an image formed on the latent image carrier to the recording sheet, A sheet cleaning roller is provided upstream of a contact portion between the latent image carrier and the transfer roller, and the sheet cleaning roller is disposed so as to abut on a portion of the recording sheet with which the feeding roller is in contact, and further includes the sheet The cleaning roller is provided with a roller cleaning means.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] A first embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view of the image forming apparatus according to the present embodiment, and FIG. 2 is a front view and a sectional view showing a pair of registration rollers. As shown in FIG. 1, in the image forming apparatus according to the present embodiment, a feeding cassette 5 for stacking recording sheets P is provided at a lower portion of the apparatus main body 1, and an image forming section 4 is disposed at an upper portion. ing.

[0010] 50 to hundreds of recording sheets P are stacked on the feeding cassette 5, and when the image forming process is activated,
The feed roller 2 rubs the uppermost recording sheet P loaded thereon and sends it to the transport path 3. The feeding roller 2 is a recording sheet P
Is arranged substantially at the center of the width of the recording sheet in order to convey the recording sheet straight.

Since the surface of the feed roller 2 is formed of a material such as rubber or resin and is larger than the frictional force between the recording sheets P, the recording sheets P are conveyed one by one. When the feed roller 2 rubs the surface of the recording sheet P in this manner, the strength of the surface of the recording sheet P is reduced by cutting or loosening the fiber only at that portion, and fluff such as fiber waste and paper dust are removed. Likely to happen.

The recording sheet P sent to the conveyance path 3 is abutted against a pair of registration rollers 6 and sent to a nip between a photosensitive drum 11 as a latent image carrier and a transfer roller 16.
The transport path 3 is formed so that the recording sheet P is reversed, that is, the surface of the recording sheet P rubbed by the feed roller 2 comes to the transfer roller 16 side. Thus, there is no need to protrude the feeding cassette from the apparatus to the side, and the apparatus main body can be downsized.

The photosensitive drum 11 is formed by forming a photosensitive layer on a conductive gas such as aluminum. The photosensitive layer has a high resistance in a dark place, but has a property of decreasing the resistance when exposed to light. ing. The conductive gas of the photosensitive drum 11 is grounded inside the image forming apparatus. The surface of the photoconductor drum 11 is uniformly charged to a predetermined potential by a charging unit 12 such as a corona charger or a charging roller, and then the photoconductor is irradiated with light corresponding to image information by an optical unit 15. An electrostatic image is formed on the drum 11.

On the other hand, the developing means 14 near the photosensitive drum 11 carries toner charged to a predetermined polarity. Then, by providing an appropriate potential difference between the photosensitive drum 11 and the developing means, the toner is moved onto the photosensitive drum 11. As a result, the image on the photosensitive drum 11 is developed, and an image visualized with toner is formed. The image on the photosensitive drum 11 is transferred to the recording sheet P by the transfer roller 16, and the toner remaining on the photosensitive drum 11 is cleaned.
Excluded by 13.

The transfer roller 16 has a resistance elastic layer provided on a metal shaft in a cylindrical shape, and is rotatably pressed against the photosensitive drum 11 so that the conveyed recording sheet P is transferred to the photosensitive drum.
The transfer process is performed while being nipped and transported by the transfer roller 11 and the transfer roller 16. At this time, a bias having a polarity opposite to the charging polarity of the toner is applied to the transfer roller 16 to transfer the toner from the photosensitive drum to the recording sheet P.

When the transfer process is completed and the recording sheet P is removed from the transfer roller portion, the transfer roller is again pressed against the photosensitive drum. The recording sheet P on which the image has been transferred is a fixing device.
The toner is fixed by being heated and pressed by 17, and is discharged out of the apparatus main body 1 by the discharge roller 18.

The timing at which the next recording sheet P arrives at the nip between the photosensitive drum 11 and the transfer roller 16 is determined by the photosensitive drum.
When the registration roller pair 6 is driven synchronously with the register 11, the image on the photosensitive drum 11 coincides with the transfer roller 16.

The upper roller 6a of the pair of registration rollers 6 shown in FIG. 2 is a metal roller, and the lower roller 6b is a plurality of elastic rollers 8 made of insulating rubber or resin arranged around a metal shaft at intervals. Configuration. The upper roller 6a and the lower roller 6b are pressurized by a spring (not shown) or the like, and are configured to be rotated by driving means (not shown). Since one upper roller 6a is made of metal, the nip position of the registration roller pair 6 is determined, and the position can be matched with the transport path 3.

As shown in FIG. 1, the lower roller 6b of the registration roller pair 6 is a roller immediately before the transfer roller 16 on the upstream side of the transport path and on the transfer roller 16 side. Therefore, as shown in FIG. 2A, a sheet cleaning roller 9 is attached substantially at the center of the lower roller 6b.

The sheet cleaning roller 9 has a surface formed of metal, has a width substantially equal to that of the feeding roller 2, and has a recording sheet P.
Are arranged so as to be able to come into contact with the contacting portion of the feeding roller 2. The sheet cleaning roller 9 has an outer diameter slightly smaller than that of the elastic roller 8 of the lower roller 6b. The slightly smaller outer diameter means that the elastic roller 8 is deformed because the upper roller 6a and the lower roller 6b of the registration roller pair 6 are in pressure contact with each other. Are configured to uniformly contact the upper roller 6a.

As shown in FIG. 2B, the sheet cleaning roller 9 is provided with a cleaning member 10 as roller cleaning means. The cleaning member 10 is a sheet of PET (polyethylene terephthalate) having a thickness of 100 μm. One end of the cleaning member 10 contacts the sheet cleaning roller 9 at an acute angle, and the other end is fixed to the apparatus main body 1. Therefore, as the sheet cleaning roller 9 rotates, the surface thereof is scratched, and the attached paper dust and foreign substances can be removed.

With the above configuration, even if the feeding roller 2 generates fluff or paper dust, the lower roller 6
b, and the cleaning member
Can be removed at 10. This allows the transfer roller 16
This reduces the amount of paper dust and the like adhering to the photosensitive drum 11, thereby reducing the influence on the formation of a latent image even in a high humidity environment.

[Second Embodiment] Next, a second embodiment according to the present invention will be described with reference to FIG. FIG. 3 is a schematic cross-sectional view of the image forming apparatus according to the present embodiment. The same reference numerals are given to the same portions as those in the first embodiment, and the description is omitted. In the first embodiment, the sheet cleaning roller 9 is provided as a part of the registration roller pair 6, but in the present embodiment, it is separately provided at a different position.

That is, as shown in FIG. 3, a sheet cleaning roller 19 is provided between the registration roller pair 6 and the transfer roller 16 and on the transfer roller 16 side of the transport path. The sheet cleaning roller 19 has a surface formed of metal, and is rotatably disposed such that the surface is at the same height as the conveying path. Therefore, when the recording sheet P is conveyed, it comes into contact with the recording sheet P and does not hinder the conveyance.

A cleaning member 20, which is a roller cleaning means made of an elastic material such as foamed polyurethane, is brought into contact with the sheet cleaning roller 19, and wipes the sheet cleaning roller 19 with the rotation of the sheet cleaning roller 19. . Accordingly, the sheet cleaning roller 19 comes into contact with the recording sheet P to adsorb the paper dust generated by the feeding roller 2, and the portion that has been wiped by the cleaning member 20 always contacts the recording sheet P.

With the above configuration, the conveying force can be increased by using the elastic roller 8 over the entire length of the registration roller pair 6. Further, since the recording sheet can be cleaned at a position closer to the transfer roller 16, the amount of paper dust generated by being rubbed in the transport path is further reduced. Therefore, there is an effect that the amount of paper dust and the like adhering to the transfer roller 16 and the photosensitive drum 11 can be further reduced.

The sheet cleaning roller 9 may be provided in a part of the registration roller pair as shown in the first embodiment, and a separate sheet cleaning roller 19 may be provided as shown in the second embodiment. This has the effect that the effect of removing paper dust and the like can be further enhanced.

In the first and second embodiments,
Since the description has been made using the transport path for reversing the recording sheet, the sheet cleaning roller is provided on the transfer roller side of the transport path. However, when the image forming apparatus is configured using a transport path that does not reverse, a sheet cleaning roller may be provided on the photosensitive drum side as a latent image carrier. That is, the effect of the present invention can be obtained by arranging the sheet cleaning roller to abut on a portion where the feeding roller comes into contact when sending out the recording sheet.

[0029]

With the above configuration, the image forming apparatus according to the present invention can reduce paper dust adhering to an image carrier or a transfer roller from a recording sheet. Therefore, the amount of paper dust adhering to the image carrier is also reduced. As a result, the latent image is not disturbed even in a high humidity environment, and a good image can be obtained irrespective of the use conditions and conditions of the apparatus.

In addition, since the sheet cleaning roller is configured as a part of a conventionally existing conveying roller, the sheet cleaning roller also has a recording sheet conveying ability. That is, since it is not necessary to newly provide a roller, there is an effect that space saving and cost reduction can be achieved.

By separately providing the sheet cleaning roller, the sheet cleaning roller can be disposed in the vicinity of the image carrier, and the paper dust newly generated in the transport path can be further reduced. Therefore, there is an effect that paper dust adhering to the image carrier is further reduced, and a good image can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an image forming apparatus according to a first embodiment.

FIG. 2 is a front view and a cross-sectional view showing a pair of registration rollers.

FIG. 3 is a schematic sectional view of the image forming apparatus according to the embodiment.

[Explanation of symbols]

 P ... Recording sheet 1 ... Main body 2 ... Supply roller 3 ... Transport path 4 ... Image forming unit 5 ... Supply cassette 6 ... Registration roller pair 6a ... Upper roller 6b ... Lower roller 8 ... Elastic roller 9 ... Sheet cleaning roller 10 … Cleaning member 11… Photoconductor drum 12… Charging means 13… Cleaning 14… Developing means 15… Rear optical means 16… Transfer roller 17… Fixer 18… Discharge roller 19… Sheet cleaning roller 20… Cleaning member

Claims (4)

[Claims] A feed cassette on which recording sheets are stacked; a feed roller for sending the recording sheets from the feed cassette; a latent image carrier; and a latent image carrier abutting on the latent image carrier. An image forming apparatus comprising: a transfer roller that transfers an image formed thereon to the recording sheet, wherein a sheet cleaning roller is provided upstream of a contact portion between the latent image carrier and the transfer roller, An image forming apparatus, wherein a cleaning roller is disposed so as to abut on a portion of the recording sheet with which the feed roller contacts. 2. The image forming apparatus according to claim 1, wherein the sheet cleaning roller has a width equal to or larger than that of the feeding roller, and has a surface formed of metal. 3. The sheet cleaning roller is a part of a transport roller for transporting the recording sheet, and the transport roller is configured such that a portion other than the sheet cleaning roller is made of a rubber or resin elastic roller. 3. The image forming apparatus according to claim 2, wherein: 4. The sheet cleaning roller according to claim 2, wherein a roller cleaning means comprising a plate-like member for scraping the sheet cleaning roller or an elastic member for wiping the sheet cleaning roller is attached. The image forming apparatus as described in the above.