JP3538390B2 - 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, and more particularly to a cleaning mechanism for removing toner remaining on a photosensitive drum after a toner image is transferred to a sheet.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic printer or a copying machine, a cleaning device made of urethane rubber or the like is used to remove toner remaining on the surface of a photosensitive drum after a toner image is transferred to a sheet. There is provided a cleaning mechanism in which the blade is brought into contact with the drum surface to scrape off the toner. As such a cleaning mechanism, in order to easily separate the toner remaining on the photoconductor drum from the drum surface, the drum surface is irradiated with a static elimination light source before performing a toner removal step by a cleaning blade, and the photoconductor drum and the toner are removed. There has been proposed an image forming apparatus in which the cleaning performance is enhanced by weakening the electrical attraction of the image.

[0003]

However, in the case of an image forming apparatus in which an image is formed by reversal development, a cleaning blade is brought into contact with the drum surface in a toner image transfer area on the surface of the photoreceptor drum, and the surface of the drum is brought into contact with the cleaning blade. By moving the residual toner to the charge residual position, the toner is easily detached from the drum surface by using the same repulsion.If the drum surface is removed before cleaning, the same repulsion effect is lost. Therefore, there is a problem that the toner hardly comes off from the drum surface, and the cleaning performance is rather deteriorated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and it is an object of the present invention to reliably remove residual toner from all areas on the surface of a photoreceptor drum irrespective of whether or not the area is a toner image transfer area. It is an object of the present invention to provide an image forming apparatus capable of performing the following.

[0005]

The invention according to claim 1 in order to achieve the above object In order to achieve the above, the photosensitive drum on which a toner image is formed on the surface by reversal development, the photosensitive drum
Charging means for uniformly charging the surface of the photosensitive drum, transfer means for transferring the toner image on the surface of the photosensitive drum onto paper, and removing toner remaining on the surface of the photosensitive drum after transfer of the toner image by the transfer means in the image forming apparatus and a cleaning means, the rotating direction of the photosensitive drum
In the downstream of the cleaning means and
It is arranged upstream of the charging means, and is located next to the photosensitive drum.
Remaining on the surface of the photosensitive drum in preparation for the toner image formation
A first static eliminator for removing the electric charge that is generated, and a first static eliminator disposed downstream of the transfer unit and upstream of the cleaning unit in the rotation direction of the photoconductor drum, and arranged in the rotation axis direction of the photoconductor drum. Area from the end of the maximum paper width to which the toner image can be transferred to the end of the photosensitive drum
And a second static elimination means for eliminating only the static electricity .

According to this configuration, the following operation is obtained. That is, the toner image transfer on the photosensitive drum surface
From the end of the maximum paper width that allows
Since the toner discharged from the developing unit due to the reverse charge is scattered and adhered to the area, the electrostatic attraction force is reduced by the second static elimination means to reduce the toner from the drum surface. It can be easily separated. on the other hand,
In the area of the photosensitive drum surface where the transfer of the toner image is performed, since the drum surface is not discharged before cleaning,
The effect that the residual toner on the drum surface is moved to the charge residual position by the cleaning means and the toner is easily separated from the drum surface by using the same polarity repulsion can be maintained.

[0007] The invention described in claim 2 is the invention according to claim 1.
Wherein the cleaning means is attached to a side of the cleaning blade in the rotation axis direction of the photosensitive drum, the cleaning blade being in contact with the photosensitive drum to scrape residual toner. The cleaning blade in the rotation axis direction of the photoconductor drum contacts the photoconductor in a region equal to or larger than the maximum paper width in contact with the photoconductor drum. The photosensitive drum is brought into contact with the photosensitive drum in a region from the cleaning blade side end to the photosensitive drum end.

According to this configuration, the toner on the surface of the photosensitive drum
Photoconductor drive from the edge of the maximum paper width where transfer of the toner image is possible.
Since the electrostatic attraction force of the toner is small in the area other than the toner image transfer area in the area up to the end of the cleaning blade, the toner is scraped off by the cleaning blade by the seal member attached to the side end of the cleaning blade. It is possible to reliably prevent the toner from passing through the side end of the cleaning blade and remaining on the surface of the photosensitive drum.

[0009] The invention according to claim 3 is based on claim 1.
3. The image forming apparatus according to claim 2, wherein the discharging unit discharges the surface of the photosensitive drum by emitting light mainly having a wavelength of about 500 to 700 nm.

In this configuration, since charge elimination by rays near ultraviolet rays and infrared rays is avoided, the photoreceptor material is deteriorated on an organic photosensitive drum or the like by rays near ultraviolet rays, and the photoreceptor is overheated by rays near infrared rays. Thus, it is possible to prevent the occurrence of problems such as that charging tends to decrease to the toner image transfer area.

The invention described in claim 4 is the first invention.
4. The image forming apparatus according to claim 3, wherein said discharging means is a light emitting diode.

According to this configuration, static elimination on the surface of the photosensitive drum can be realized with a simple configuration.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a schematic configuration of an image forming apparatus according to the present invention. As shown in FIG. 1, a copying machine (an example of an image forming apparatus) 1 forms an image by reversal development. The photosensitive drum 4 is charged uniformly by a laser beam from a laser scanning unit (not shown) based on a document image read by a document reading unit 5.
An electrostatic latent image is formed thereon, and toner adheres to the electrostatic latent image by the developing device 7 to form a toner image.

The paper is fed from the paper feed mechanism 9 to the paper transport path 1 toward the photosensitive drum 4 on which the toner image is formed as described above.
0, and the toner image on the surface of the photosensitive drum 4 is transferred to a sheet. Then, the sheet on which the toner image has been transferred is separated from the photosensitive drum 4 and is conveyed to a fixing device 12 having a heat roller 121 and a pressure roller 122, where the toner image is fixed. Heat roller 121 and pressure roller 122
The paper that has passed through the nip portion of
3, the sheet is conveyed to a switchback unit 17 by being switched to a switchback unit 17 by changing the conveying direction of the sheet by a branching member 16 provided at a branch point of the sheet conveying path 15, and then again. At the transfer position of the photoconductor drum 4, the toner image is transferred to the back surface side and copied on both sides, and then discharged to the discharge unit 14. Reference numeral 18 denotes a cleaning unit that removes residual toner and the like on the photosensitive drum 4. The photosensitive drum 4 by the cleaning unit 18 or the like
Is a feature of the present invention.

Reference numeral 19 denotes a document transport unit that transports a document to the document reading unit 5 to read a document image. The paper feeding mechanism 9 is detachably attached to the copying machine main body 2,
Paper feed cassettes 91, 92, 93, 94 for storing paper
And a paper feed tray 95 provided thereabove. These are connected to the developing device 7 and the photosensitive drum 4 by a paper transport path 10.

Next, a cleaning mechanism for the photosensitive drum 4 will be described. FIG. 2 is a schematic diagram showing the photosensitive drum 4 and its peripheral mechanism. Around the photosensitive drum 4,
A charging unit 3 for uniformly charging the surface of the photosensitive drum 4; laser scanning for irradiating reflected light of a document to remove charges from the charged surface of the photosensitive drum 4 to form a latent image A developing unit 7 for supplying a toner charged to the same polarity as the surface of the photosensitive drum 4 on the surface of the photosensitive drum 4 on which the latent image has been formed; A transfer device 21 for transferring the toner image on the surface onto the paper P is provided. Further, a cleaning unit 18 is disposed downstream of the transfer device 21 in the rotation direction of the photosensitive drum 4 (the direction of the arrow in FIG. 2).

The cleaning section 18 has a cleaning blade 23 which comes into contact with the surface of the photosensitive drum 4 at a predetermined contact pressure to scrape off residual toner on the drum surface, and a cleaning blade 2 in the rotation axis direction of the photosensitive drum 4.
3, a fur brush 25 for cleaning the drum surface by contacting the surface of the photosensitive drum 4 on the upstream side of the cleaning blade 23 and the seal member 24; A spiral 26 for collecting the toner and the like removed from the surface in one place. Cleaning blade 23
Is a plate-like elastic body made of urethane rubber or the like extending in the rotation axis direction of the photosensitive drum 4, the seal member 24 is made of a sponge, a brushed seal, or the like.
This is to prevent the toner scraped by 3 from slipping through the side end of the cleaning blade 23. Further, on the downstream side of the cleaning unit 18, there is provided a static eliminator 27 that removes the charge remaining on the surface of the photosensitive drum 4 in preparation for the next toner image formation.

Further, on the upstream side of the fur brush 25 and on the downstream side of the transfer device 21, a discharge lamp (discharge means) 28 for discharging the surface of the photosensitive drum 4 is provided. The static elimination lamp 28 is composed of a light emitting diode or the like, and is attached to the housing 18a of the cleaning unit 18.

Next, the irradiation of the surface of the photosensitive drum 4 by the charge removing lamp 28 and the irradiation range will be described. FIG.
FIG. 4 is a diagram showing an irradiation range of the charge removing lamp 28 on the surface of the photosensitive drum, and a cleaning range by the cleaning blade and the seal member. Cleaning blade 23
Is in contact with the surface of the photosensitive drum 4 in a region slightly larger than the maximum width of the sheet P on which the toner image is transferred by the photosensitive drum 4 in the rotation axis direction of the photosensitive drum 4, and the seal member 24 is cleaned. The region from the side end of the blade 23 to the end of the photosensitive drum 4 is in contact with the photosensitive drum 4. The range of irradiation by the charge removing lamp 28 is a region from the maximum width of the sheet P on which the toner image is transferred by the photosensitive drum 4 to the end of the photosensitive drum 4.

In this way, in the toner image transfer area, the toner is moved to the charge remaining position by the cleaning blade 23, and the toner is separated by the same polarity repulsion using the charge on the drum surface, while maintaining the effect. Feeling
The largest possible toner image transfer on the surface of the optical drum 4
In the region from the end of the sheet width to the end of the photosensitive drum, the charge on the drum surface is removed by the charge removing lamp 28 and the electrostatic attraction force is reduced, so that the toner is reversely charged and adheres to the drum surface. Can be easily separated.

Further, the charge elimination of the drum surface by the charge elimination lamp 28 is performed by emitting a light beam mainly having a wavelength of about 500 to 700 nm. Irradiation of light near ultraviolet rays causes deterioration of photosensitive material in an organic photosensitive drum or the like,
This is because irradiation with a light beam near infrared rays causes a problem that the photosensitive member is overheated, and the charge in the toner image transfer area is easily reduced. In particular, in the case of a single-layer organic photoreceptor, the light elimination efficiency is high according to the light mainly having a wavelength of about 640 to 680 nm. However, the wavelength of the light beam used for static elimination is appropriately changed according to the constituent material of the photoconductor.

The present invention is not limited to the configuration of the above-described embodiment, but can be variously modified. For example, in the above-described embodiment, the static elimination lamp 28 is made of a light emitting diode. However, another device that can neutralize the surface of the photosensitive drum 4 can be used. Further, in the above-described embodiment, the static elimination lamp 28 is provided on the housing 18a of the cleaning unit 18. However, if the discharge lamp 28 is on the downstream side of the transfer device 21 and on the upstream side of the cleaning unit 18, it may be disposed at another position. It does not matter.

[0023]

As described above, according to the present invention, the maximum paper width capable of transferring the toner image on the surface of the photosensitive drum is provided.
In the region from the end to the end of the photosensitive drum , by removing the static electricity before cleaning to reduce the electrostatic attraction force,
The oppositely charged toner adhering to the drum surface can be easily separated from the drum surface, while in the area of the photosensitive drum surface where the toner image is transferred, the drum surface is not discharged before cleaning. In addition, it is possible to maintain the effect that the residual toner on the drum surface is easily released by using the repulsion .

Further, if a structure is adopted in which a seal member attached to the cleaning blade side end in the rotation axis direction of the photosensitive drum is brought into contact with the photosensitive drum, the toner image on the surface of the photosensitive drum is removed by the static elimination means. Transcription
From the end of the maximum paper width to the end of the photosensitive drum
Because the electrostatic attraction force of the toner is small in the area , the sealing member reliably prevents the toner scraped by the cleaning blade from slipping through the side edge of the cleaning blade and remaining on the surface of the photosensitive drum. can do.

If the surface of the photosensitive drum is neutralized by emitting light mainly having a wavelength of about 500 to 700 nm, the photosensitive material such as the organic photosensitive drum is deteriorated by light near the ultraviolet rays. In addition, it is possible to prevent the problem that the photosensitive member is overheated by a light ray near infrared rays and the charge is easily reduced to the toner image transfer area.

When the charge removing means is constituted by a light emitting diode, the charge removal on the surface of the photosensitive drum can be realized with a simple structure.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a schematic configuration of an image forming apparatus according to the present invention.

FIG. 2 is a schematic diagram illustrating a photosensitive drum and a peripheral mechanism thereof.

FIG. 3 is a diagram illustrating an irradiation range of a static elimination lamp on a photosensitive drum surface, and a cleaning range by a cleaning blade and a seal member.

[Explanation of symbols]

1 Copier (image forming apparatus) 4 Photoconductor drum 18 Cleaning unit 21 Transfer device 23 Cleaning blade 24 Sealing member 28 Static elimination lamp P paper

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) G03G 21/08 G03G 15/00 303 G03G 21/00 370-540 G03G 21/14

Claims (4)

(57) [Claims] A photosensitive drum on which a toner image is formed by reversal development ;
Having a charging unit that charges, a transfer unit for transferring the toner image on the photosensitive drum surface to the paper, and a cleaning means for removing toner remaining on the photosensitive drum surface by the transfer means after the toner image is transferred to the In the image forming apparatus, the cleaning may be performed in a rotation direction of the photosensitive drum.
Located downstream of the charging means and upstream of the charging means
To prepare for the next toner image formation on the photosensitive drum.
To remove charges remaining on the surface of the photosensitive drum by
And a maximum that is capable of transferring a toner image in the rotation axis direction of the photoconductor drum, which is disposed downstream of the transfer unit and upstream of the cleaning unit in the rotation direction of the photoconductor drum. And a second static eliminator for neutralizing only the area from the end of the sheet width to the end of the photosensitive drum.
Image forming apparatus characterized by that. 2. The cleaning device according to claim 1, wherein the cleaning unit includes a cleaning blade that abuts on the photoconductor drum to scrape off residual toner, and a seal member attached to a side end of the cleaning blade in a rotation axis direction of the photoconductor drum. In the rotation axis direction of the photoconductor drum, the cleaning blade contacts the photoconductor in a region equal to or larger than a maximum sheet width that contacts the photoconductor drum, and the seal member is an end of the cleaning blade. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus contacts the photosensitive drum in a region from the end to the end of the photosensitive drum. 3. The method according to claim 2, wherein the second static elimination means is about 500-70.
3. The image forming apparatus according to claim 1, wherein the surface of the photosensitive drum is neutralized by emitting a light beam having a wavelength of 0 nm as a main component. 4. The image forming apparatus according to claim 1, wherein said discharging means is a light emitting diode.