JP2002296990A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus which surely removes remaining toner on all the areas of the surface of a photosensitive drum whether or not these areas are toner image transfer areas. SOLUTION: In the image forming apparatus which forms an image by reverse development, a destaticizing lamp which destaticizes the surface of a photosensitive drum 4 is arranged below a transfer device and above a cleaning part in the rotating direction of the photosensitive drum 4, and the range in which the surface of the photosensitive drum 4 is destaticized by the destaticizing lamp is set to areas from end parts of a maximum paper sheet P, to which a toner image can be transferred, to end parts of the photosensitive drum 4 in the rotation axis direction of the photosensitive drum 4.

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 transferring a toner image 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 a toner remaining on the surface of a photosensitive drum after a toner image is transferred to a sheet. A cleaning mechanism is provided to abut the blade on 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 removing 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 electric 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 the toner image transfer area on the surface of the photoreceptor drum. By moving the residual toner to the charge residual position, the toner is easily separated from the drum surface by using the same polarity repulsion.If the drum surface is removed before cleaning, the same polarity 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 the entire surface of a photoreceptor drum irrespective of whether a toner image is transferred. It is an object of the present invention to provide an image forming apparatus capable of performing the following.

[0005]

According to a first aspect of the present invention, there is provided a photosensitive drum having a surface on which a toner image is formed by reversal development, and a toner image on the surface of the photosensitive drum. Transfer means for transferring the toner image onto the paper, cleaning means for removing toner remaining on the surface of the photosensitive drum after the transfer of the toner image by the transfer means, and a downstream side of the transfer means in the rotational direction of the photosensitive drum. And a charge eliminator disposed on the upstream side of the cleaning unit for eliminating charge on the surface of the photosensitive drum. , The area from the maximum paper width to which the toner image can be transferred to the end of the photosensitive drum.

According to this configuration, the following operation is obtained. That is, since the toner discharged from the developing unit by reverse charging is scattered and attached to the charged area other than the toner image transfer area on the surface of the photosensitive drum, the area is electrostatically attracted by removing the charge by the charge removing unit. By reducing the force, the toner can be easily separated from the drum surface. On the other hand, in the area of the photosensitive drum surface where the transfer of the toner image is performed, the drum surface is not neutralized before cleaning. Therefore, the effect that the toner is easily separated from the drum surface can be maintained.

[0007] The invention described in claim 2 is the first invention.
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 sheet width in contact with the photoconductor drum, and the seal member is 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, since the electrostatic attraction of the toner is small in the area other than the toner image transfer area, 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 slipping through the side end of the cleaning blade and remaining on the surface of the photosensitive drum.

[0009] The invention described in claim 3 is the first invention.
3. The image forming apparatus according to claim 2, wherein the charge removing unit removes the charge on the surface of the photosensitive drum by emitting light 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 deteriorates on an organic photosensitive drum or the like due to rays near ultraviolet rays, and the photoreceptor is overheated by rays near infrared rays. Thus, it is possible to prevent the occurrence of a problem such as that the charge is easily reduced 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, the charge 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, and a photoconductor which rotates in a direction A in FIG. The drum 4 is uniformly charged, and the photosensitive drum 4 is irradiated with a laser beam from a laser scanning unit (not shown) based on the document image read by the 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 photosensitive drum 4 on which the toner image has been 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 to fix the toner image. Heat roller 121 and pressure roller 122
Paper that has passed through the nip portion of
3, the sheet is transported to the switchback unit 17 by being switched by the branching member 16 provided at the branch point of the paper transport path 15 to the discharge unit 14, and is transported to the switchback unit 17. At the transfer position of the photoconductor drum 4, the toner image is transferred to the back surface side, and both sides are copied, 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 for reading 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, and 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 an original to remove charges from the charged surface of the photosensitive drum 4 to form a latent image A unit 20, a developing device 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 is formed, and a corona charging opposite to the toner charging to perform 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 at 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 for removing 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 an area 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 irradiation range of the discharge lamp 28 is defined as 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 utilizing the charge on the drum surface, while maintaining the effect. In the area other than the toner image transfer area, 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 adhering to the drum surface by reverse charging can be easily separated. it can.

The discharge of the drum surface by the discharge lamp 28 is performed by emitting light having a wavelength of about 500 to 700 nm. Irradiation of light near ultraviolet rays causes deterioration of photoreceptor materials in organic photoreceptor drums and 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, and various modifications are possible. 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. In the above embodiment, the discharge 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, in the area other than the toner image transfer area on the surface of the photosensitive drum, the charge is removed before cleaning to reduce the electrostatic attraction force, thereby causing the drum to be reverse-charged. The toner adhering to the surface can be easily separated from the drum surface. On the other hand, in the area of the photosensitive drum surface where the toner image is transferred,
Since the charge on the drum surface is not removed before cleaning, the effect that the residual toner on the drum surface is easily separated by using the same polarity repulsion can be maintained. This allows
Irrespective of whether the area is the toner image transfer area or not, the residual toner can be reliably removed from all areas on the surface of the photosensitive drum.

Further, if a configuration 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, in a region other than the toner image transfer region due to static elimination by the static elimination means. Since the electrostatic attraction force of the toner is reduced, the seal 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. it can.

Further, 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 the light near the ultraviolet rays. Also, it is possible to prevent a 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 view showing 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]

 DESCRIPTION OF SYMBOLS 1 Copier (image forming apparatus) 4 Photoconductor drum 18 Cleaning part 21 Transfer device 23 Cleaning blade 24 Seal member 28 Static elimination lamp P Paper

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H035 AA09 AA10 AB02 AC04 2H134 GA01 GB02 HB00 HD01 HD05 HD19 JA02 KD08 KF03 KF06 KG03 KH01 KH15 KJ05

Claims (4)

[Claims] A photosensitive drum having a toner image formed on the surface thereof by reversal development; a transfer unit for transferring the toner image on the photosensitive drum surface to a sheet; and a photosensitive drum after the transfer of the toner image by the transfer unit. Cleaning means for removing toner remaining on the surface; and static elimination for removing static electricity from the surface of the photosensitive drum, the cleaning means being disposed downstream of the transfer means and upstream of the cleaning means in the rotation direction of the photosensitive drum. In the image forming apparatus having the means, the static elimination range of the surface of the photosensitive drum by the static elimination means, in the rotation axis direction of the photosensitive drum, from the maximum paper width capable of transferring a toner image to the end of the photosensitive drum An image forming apparatus comprising: an area. 2. The cleaning device according to claim 1, wherein the cleaning unit includes: a cleaning blade that abuts on the photosensitive 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 photosensitive drum. In the rotation axis direction of the photoconductor drum, the cleaning blade contacts the photoconductor in a region equal to or greater than a maximum sheet width that contacts the photoconductor drum, and the sealing 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. 3. The image according to claim 1, wherein the charge removing unit removes the charge on the surface of the photosensitive drum by emitting light mainly having a wavelength of about 500 to 700 nm. Forming equipment. 4. The image forming apparatus according to claim 1, wherein said charge removing means is a light emitting diode.