JP2004004749A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of prolonging the lives of a cleaning means and an electrostatic charging member by preventing an electrostatic charging roller from temporally being stained with paper powder, etc., by an inexpensive mechanism. <P>SOLUTION: The image forming device 1 which has a plurality of photoreceptors 3 arranged and transfers toner images on the photoreceptors 3 to a recording medium through an intermediate transfer body 7 has an electrostatic charging member 4 arranged in contact with or nearby the photoreceptors 3. Further, the image forming device 1 has at least one cleaning means 5 of removing foreign matter sticking on the surface of the electrostatic charging member 4 by abutting against the electrostatic charging member. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus such as a copier, a printer, and a facsimile that uses an electrophotographic process.
[0002]
[Prior art]
In the image forming apparatus, the photosensitive member is charged by a charging member, and then a latent image is formed by a laser beam or the like, and the latent image is developed with a toner of 10 μm or less to form a toner image. The toner image is transferred to a transfer sheet, and is fused and fixed by a heat roller or the like, and an image is recorded on the transfer sheet. At this time, the charging member that is placed in contact with or in close proximity to the photoconductor changes its resistance value due to foreign substances adhering to the surface over a long period of use, resulting in uneven charging, insufficient charging, etc. An abnormal image is generated due to the charging failure.
Examples of the foreign matter include residual toner on the photoreceptor and paper dust generated from the transfer paper. The photoreceptor is provided with a photoreceptor cleaning unit to remove these. However, those having a small particle diameter or those having a nearly spherical shape pass through the photoreceptor cleaning means and gradually adhere to the surface of the charging member located downstream thereof. Further, paper dust, toner, dust and the like floating in the machine gradually adhere to the charging member, and the resistance value of the charging member is changed by long-term use, and an abnormal image is generated.
[0003]
As a countermeasure against the occurrence of an abnormal image, for example, Patent Documents 1 and 2 disclose a charging device that removes foreign substances on the surface by pressing a pad-shaped member on a charging member.
Patent Document 3 discloses a charging roller cleaning device that includes a flexible member that can be flexibly deformed, and makes the surface of the flexible member contact the charging roller to clean the surface of the charging roller.
[0004]
However, in Patent Literature 1 or 2, the pad-shaped one is pressed against the charging member in a state where the foreign matter is captured, and therefore, when the foreign matter contains the toner or its additive, it is rubbed against the charging member. In such a case, a minute film-like film is formed on the charging member due to long-term use by the action of pressing, frictional heat, or the like, and the charging function may be impaired. Furthermore, since the contact area with the charging member that actually contributes to cleaning is small, it is difficult to maintain the cleaning effect for a long time. Further, if an attempt is made to increase the contact area, it is conceivable to increase the size of the pad, but there is a problem that the device becomes large. Further, in Patent Literature 3, it is difficult to maintain the cleaning effect for a long time because the cleaning unit of the charging member has only a very small area where the cleaning member actually contacts the charging member and exerts the cleaning effect. In addition, since the intermediate transfer member is provided in the apparatus main body, and the photoconductor and the transfer paper do not directly contact each other, the amount of paper dust adhering to the transfer paper entering the charging member via the photoconductor is small, which is advantageous. Although there is only one photoreceptor for a developing machine for a plurality of colors, paper powder input to the charging member via the intermediate transfer member and the photoreceptor is all deposited on one charging member although it is small. This is not preferable in a full-color image forming apparatus in which uneven charging and the like are conspicuous.
[0005]
[Patent Document 1]
JP-A-8-123140 [Patent Document 2]
JP-A-9-222776 [Patent Document 3]
JP-A-11-288150
[Problems to be solved by the invention]
Therefore, the present invention has been made in view of the above circumstances, and an object thereof is to provide an image forming apparatus that can prevent a charging roller from being stained with paper dust or the like that occurs over time with an inexpensive mechanism. . Another object of the present invention is to provide an image forming apparatus that can extend the life of the cleaning unit and the life of the charging member with an inexpensive mechanism.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, an image forming apparatus according to claim 1, wherein a plurality of image carriers are arranged, and a toner image on the image carrier is transferred onto a recording medium via an intermediate transfer member. An image forming apparatus having a charging member that is disposed in contact with or in close proximity to an image carrier, wherein the image forming apparatus includes a cleaning unit that removes a foreign substance attached to a surface by contacting the charging member. An image forming apparatus having at least one or more.
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the number of the cleaning units for removing foreign matters adhering to the charging member in contact with the charging member is smaller than the number of the charging members. If the number is smaller, the cleaning unit is an image forming apparatus provided on a member for charging the image carrier located on the upstream side in the rotation direction of the intermediate transfer body.
According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the image forming apparatus includes a brush as a cleaning unit that removes a foreign substance attached to a surface by contacting the charging member. Device.
According to a fourth aspect of the present invention, in the image forming apparatus according to the third aspect, the image forming apparatus is configured such that the brush abuts on the surface of the charging member by its own weight and rotates following the movement of the charging member. It is.
According to a fifth aspect of the present invention, in the image forming apparatus according to the third aspect, the image forming apparatus is an image forming apparatus in which the brush moves at a speed different from the moving speed of the charging member.
[0008]
According to a sixth aspect of the present invention, in the image forming apparatus according to the third or fourth aspect, the image forming apparatus is configured such that a length of a fiber of a brush is set to 2 mm or less.
According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the third, fourth, and sixth aspects, the image forming apparatus is configured such that a charging member disposed in contact with or in close proximity to the image carrier has AC. This is an image forming apparatus to which a voltage and a DC voltage are applied in a superimposed manner.
According to an eighth aspect of the present invention, in the image forming apparatus according to any one of the first to seventh aspects, the image forming apparatus is an image forming apparatus in which at least the vicinity of a charging member is substantially sealed.
A ninth aspect of the present invention is the image forming apparatus according to any one of the first to eighth aspects, wherein the toner used is a toner manufactured by a polymerization method. .
According to a tenth aspect of the present invention, in the image forming apparatus according to any one of the first to eighth aspects, the image forming apparatus includes a process cartridge in which at least a charging member and a cleaning unit for the charging member are arranged. And
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic diagram illustrating a configuration of an image forming apparatus that is an example of an embodiment of the present invention.
In the image forming apparatus 1, four photoreceptors 3, a developing device 2, a charging member 4, a charging member cleaning member 5, and a photoreceptor cleaning device 6 are arranged four each. The developing device 2 contains four color toners of black, yellow, magenta, and cyan, respectively, and can perform full-color printing. The toner image visualized on the photoconductor 3 by a well-known process is transferred to the intermediate transfer member 7 at a contact with or close to the intermediate transfer member 7 (primary transfer portion). The toner image on the intermediate transfer member 7 is transferred onto the transfer paper 9 at a contact position with or close to the secondary transfer member 10 (secondary transfer portion), and is fixed by a fixing device (not shown).
[0010]
The transfer paper 9 is sent from the paper supply cassette 12 to the registration roller pair 11 by the paper supply roller 13 and is conveyed to a secondary transfer process site at a predetermined timing. Paper dust generated by friction between the paper feed roller 13 and the registration roller pair 11 and part of paper dust generated at the time of cutting the transfer paper and adhering to the transfer paper as they are are transferred to the intermediate transfer member at the secondary transfer portion. 7 adheres. The paper dust on the intermediate transfer body 7 is removed by the cleaning unit 14, but a part of the paper dust slides through the cleaning unit 14 and adheres to the photoconductor 3 at the primary transfer portion. These are removed by the photoreceptor cleaning device 6, but a part thereof slips through the cleaning device 6 and adheres and accumulates on the surface of the charging member 4. In the configuration of the present invention, a part of the paper dust on the transfer paper 9 moves to the intermediate transfer member 7, and a part of the paper powder moves to the photoconductor 3. Further, the intermediate transfer member 7 is provided with a cleaning means 14 which is always in contact with the photoreceptor 3 with the paper dust removed, so that the amount of paper dust is input to the photoreceptor 3 in a state where the amount is sufficiently reduced. You. Therefore, the amount of paper dust adhering and accumulating on the charging member 4 is reduced as compared with an apparatus having a conventional configuration without the intermediate transfer member 7. Further, since four photosensitive members 3 and four charging members 4 are provided, the intermediate transfer member 7 is provided as in the invention described in Patent Document 3 described in the section of the related art, but paper dust from the intermediate transfer member 7 is provided. Is not concentrated on one charging member 4, the amount of paper dust adhering and accumulating on the surface of one charging member 4 is extremely small.
[0011]
FIG. 2 is a schematic view illustrating an example of the charging member cleaning member used in the image forming apparatus of the present invention.
The charging member cleaning member 5 is a roller-shaped brush. Since the entire outer diameter of the brush can contribute to cleaning, compared to a pad-like cleaning member such as a foamed elastic body or felt, the brush can have a larger area that can be cleaned, and the cleaning ability can be maintained for a long time. In addition, the cleaning effect can be maintained with a smaller one as compared with a pad-shaped one.
The charging member cleaning member 5 comes into contact with the surface of the charging member 4 by its own weight in a predetermined direction by a guide 15, and is rotated by the rotation of the charging member 4. Since the pressure on the charging member 4 is set by the weight of the brush, a member that regulates the amount of the brush that bites into the charging member 4 is not required, which contributes to cost reduction. At this time, it is preferable to set the bristle length of the brush to about 2 mm or less, because the amount of elastic deformation of the brush fiber can be reduced and the brush fiber can be prevented from falling over for a long period of time.
In addition, by performing the driven rotation, the effect can be obtained at low cost without providing a driving unit. A moving speed difference from the surface of the charging member 4 may be intentionally provided by a gear or the like (not shown) to positively scrape to further improve the cleaning effect.
[0012]
In the image forming apparatus illustrated in FIG. 1, the cleaning unit 5 is illustrated for all the charging members 4, but is not necessarily provided for all of the charging members 4. In other words, the number of the cleaning means 5 for removing the foreign matter adhering to the charging member in contact with the charging member may be smaller than the number of the charging members 4. For example, as shown in FIG. 3, the cleaning unit 5 may be provided only for the two charging members 4 located upstream of the intermediate transfer body 7 in the rotation direction. This is because, in a system having the intermediate transfer member 7, the amount of paper dust input to the photosensitive member 3 is extremely small. Further, most of the paper dust on the intermediate transfer body 7 moves to the photoconductor 3 located at the uppermost stream in the rotation direction of the intermediate transfer body 7, and there is almost no paper dust on the intermediate transfer body 7 downstream thereof. Therefore, if the cleaning unit 5 is provided only for the charging member 4 that charges the photosensitive member 3 located at the most upstream position in the rotation direction of the intermediate transfer member 7, the effect can be obtained at low cost. When the number of the cleaning means 5 is smaller than the number of the charging members and a plurality of cleaning members are provided, it is preferable to arrange the cleaning members 5 in order from the charging member located on the upstream side in the rotation direction of the intermediate transfer body 7. As a result, most of the very small amount of entering paper powder adheres to the photoconductor 3 at the uppermost stream of the intermediate transfer member 7. Therefore, if the charging cleaning member 5 is installed in that portion, unnecessary cleaning means 5 can be eliminated. By not providing this, it is possible to prevent the charging member 4 from being stained by paper dust or the like while realizing a low cost.
If the type of toner to be used, the bias condition applied to the charging member 4 and the like are different for each photoconductor 3 station, it is assumed that the influence of foreign matter on the surface of the charging member 4 is different due to the influence. Alternatively, the cleaning means 5 may be provided in the order of easy attachment.
[0013]
The substance adhering and depositing on the surface of the charging member 4 is not limited to paper powder. Various things such as toner not removed by the photoreceptor cleaning unit 6, additives contained in the toner, and dust floating in the main body of the image forming apparatus 1 are deposited. The foreign substances that slide through the photoconductor cleaning means 6 are not uniform in the entire area of the photoconductor 1 in the generatrix direction. Therefore, the amount of foreign substances deposited on the surface of the charging member 4 varies in the longitudinal direction. Accordingly, the resistance value unevenness of the charging member 4 occurs. In the present invention, since both AC and DC voltages are superimposed on the charging member 4 from a power supply (not shown), the uniformity of the charging potential can be increased by the effect of the AC voltage component as compared with the application of the DC voltage alone. Since it is possible, even if the resistance value unevenness of the charging member 4 occurs, it is possible to make the unevenness of the charging potential less noticeable.
[0014]
Further, by making the toner included in the developing device 2 a toner produced by a polymerization method, it is possible to further suppress the adhesion of dirt on the surface of the charging member 4. The foreign matter adhering to the surface of the charging member 4 includes toner that has passed through the photoconductor cleaning unit 6. Since the toner prepared by the polymerization method has an extremely uniform charge-to-charge mass ratio for each particle, the transfer efficiency in the electrostatic transfer step can be extremely increased. As a result, the amount of toner input to the photoreceptor cleaning unit 6 is smaller than that of the conventional toner, so that the amount of toner that slips through and adheres to the surface of the charging member 4 is also reduced.
At this time, by making the shape of the toner not a shape close to a true sphere, but a distorted shape, the toner can be easily scraped off by the photoconductor cleaning means 6, and the effect can be further improved.
[0015]
FIG. 4 is a schematic diagram illustrating an example of a process cartridge used in the image forming apparatus of the present invention.
The above configuration may be configured as a process cartridge. As shown in FIG. 4, when the vicinity of the charging member 4 is substantially sealed, the chance of contact with dust or the like floating in the main body of the image forming apparatus 1 is reduced, and further, the adhesion of dirt to the surface of the charging member 4 is suppressed. It is effective.
FIG. 4 shows a process cartridge in which the photoreceptor 3, the charging member 4, the developing member 2a, and the photoreceptor cleaning member 6 are integrally formed. Only the transfer portion is opened, and the other portions are substantially closed. The exposure section is also sealed with the transparent member 16. In the present embodiment, the entire process cartridge is configured to be substantially sealed. However, only the vicinity of the charging member 4 may be sealed.
Since the life of the charging member 4 which has an earlier life in the conventional process cartridge can be greatly improved, the life of the charging member 4 allows the advantages of the process cartridge to be utilized without shortening the life of the entire process cartridge. it can.
[0016]
【The invention's effect】
As described above, in the image forming apparatus of the present invention, the toner image on the photoreceptor is transferred to the paper via the intermediate transfer member. The amount of paper dust that passes through the means and accumulates on the charging roller is drastically reduced, and the life of the charging member can be extended. Further, the number of cleaning members for the charging member can be reduced, and the cost can be reduced.
In particular, in a full-color image forming apparatus, an abnormal image is remarkably generated due to charging unevenness due to minute resistance unevenness of the charging roller due to adhesion of foreign matter because toners of a plurality of colors are superimposed. The occurrence of an abnormal image can be suppressed by reducing the amount of powder.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating a configuration of an image forming apparatus according to an embodiment of the invention.
FIG. 2 is a schematic diagram illustrating an example of a charging member cleaning member used in the image forming apparatus of the present invention.
FIG. 3 is a schematic diagram illustrating a configuration of an image forming apparatus in a case where the number of charging member cleaning members is smaller than the number of charging members according to an embodiment of the present invention.
FIG. 4 is a schematic view illustrating an example of a process cartridge used in the image forming apparatus of the present invention.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 image forming device 2 developing device 3 photoreceptor 4 charging member 5 cleaning means 6 photoreceptor cleaning device 7 belt 8 primary transfer device 9 transfer paper 10 secondary transfer device 11 registration roller 12 paper feed cassette 13 pickup roller 14 intermediate transfer member Cleaning device 15 Guide 16 Transparent member

Claims (10)

An image forming apparatus in which a plurality of image carriers are arranged, and a toner image on the image carrier is transferred onto a recording medium via an intermediate transfer body. In an image forming apparatus having a member,
The image forming apparatus has at least one cleaning unit that removes a foreign substance attached to a surface of the image forming apparatus by contacting the charging member. The image forming apparatus according to claim 1,
In the image forming apparatus, when the number of cleaning means for removing foreign substances adhering to the charging member and adhering to the surface is smaller than the number of charging members, the cleaning means is located on the upstream side in the rotation direction of the intermediate transfer member. An image forming apparatus provided on a charging member. The image forming apparatus according to claim 1, wherein
The image forming apparatus is characterized in that the cleaning means for removing foreign matter adhering to the surface by contacting the charging member is a brush. The image forming apparatus according to claim 3,
The image forming apparatus is characterized in that the brush contacts the surface of the charging member by its own weight and rotates following the movement of the charging member. The image forming apparatus according to claim 3,
The image forming apparatus is characterized in that the brush moves at a speed different from the moving speed of the charging member. The image forming apparatus according to claim 3, wherein
The image forming apparatus, wherein the length of the fiber of the brush is set to 2 mm or less. The image forming apparatus according to any one of claims 3, 4, and 6,
The image forming apparatus is characterized in that an AC voltage and a DC voltage are superimposed and applied to a charging member arranged in contact with or close to the image carrier. The image forming apparatus according to claim 1, wherein
The image forming apparatus is characterized in that at least the vicinity of the charging member is substantially sealed. The image forming apparatus according to claim 1, wherein
The image forming apparatus is characterized in that the toner used is a toner manufactured by a polymerization method. The image forming apparatus according to claim 1, wherein
The image forming apparatus includes a process cartridge in which at least a charging member and a cleaning unit for the charging member are arranged.

Images