JP2004109721A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus having a cleaning means whose cleaning capacity is high and which has excellent durability and a cleaning means whose cleaning capacity is high and which prevents discharge unevenness after cleaning. <P>SOLUTION: The image forming apparatus is provided with a corona electrifier 2 where voltage is applied to a wire 20, corona discharge is performed and electrostatic charge is given to a photoreceptor 1 and the cleaning means cleaning foreign matters adhered to the wire 20 by rubbing. A cleaning pad 21 whose part into contact with the wire 20 is formed in a groove shape is disposed as the cleaning means. In cleaning, the wire 20 is fitted to the groove shape part. Thus, the wire 20 can be cleaned without contact unevenness for a whole circumference. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus including a corona charger for applying a voltage to a thin wire to perform corona discharge to impart an electrostatic charge to a member to be charged, and a cleaning unit for rubbing the fine wire to remove foreign matter attached thereto. Things.
[0002]
[Prior art]
In an electrophotographic apparatus, the surface of a photoreceptor is charged by a charger. As a representative means of the charger, there is a charger by corona discharge. FIG. 5 is an explanatory diagram illustrating the principle of the corona charger. As shown in FIG. 5, the corona charger 100 performs corona discharge by applying a high voltage of several kV to a wire 101 mainly composed of a tungsten wire. Then, the elements in the air are ionized, and the ions 102 are attached to the surface of the photoconductor 103 to charge the photoconductor 103. At this time, various substances in the air are ionized, and the ionized substances are electrically attached to the wires 101 because the elements in the air are charged by causing dielectric breakdown. Among the adhered substances, there are foreign substances that hinder corona discharge. Silica (SiO ₂ ), which is an additive to the developing toner, is one of them. When the amount of the foreign matter attached increases, the portion is not discharged, and the entire image area is not uniformly charged, so that an image having uneven density (raindrop image) is formed. Therefore, it is necessary to periodically clean the wire 101 before the amount of attached matter increases.
[0003]
FIG. 6A is a cross-sectional view illustrating the configuration of a conventional cleaning mechanism, and FIG. 6B is a front view. As shown in FIG. 6, the cleaning mechanism includes a cleaning pad 103 made of rubber, sponge, or the like, and a pad holding member 104 that holds the cleaning pad 103. Then, after reaching a certain number of image formations, the pad holding member 104 automatically moves along the wire 101, and the cleaning pad 103 rubs the wire 101 to remove foreign matter attached to the wire 101 (for example, see Patent Reference 1).
[0004]
[Patent Document 1]
JP-A-2001-343813
[Problems to be solved by the invention]
However, the conventional cleaning mechanism has the following problems. FIG. 7 is a cross-sectional view showing a state of a conventional cleaning pad and a wire having a hard surface. FIG. 8A is a cross-sectional view showing a state of a conventional soft cleaning pad and a wire, and FIG. 8B is a front view. FIG. 9 is a cross-sectional view illustrating a state of the cleaning pad in which the pad has been cut.
As shown in FIG. 7, when the wire 101 is cleaned by a pair of cleaning pads 105 having a hard surface, for example, a portion that does not contact the wire 101 is generated. As a result, there is a portion where foreign matter adhering to the wire 101 cannot be removed, and the cleaning ability is reduced. On the other hand, as shown in FIG. 8, when the wire 101 is cleaned with a pair of soft cleaning pads 106, the cleaning pad 106 hits almost the entire surface of the wire 101, so that the cleaning ability is improved. However, since the cleaning pad 106 is soft, it is susceptible to damage by foreign matter, and the pad starts to be broken after several cleanings. As shown in FIG. 9, when the pad is cut, the sliding force between the cleaning pad 106 and the wire 101 is reduced, so that the cleaning ability is deteriorated with time and the durability is poor. As described above, in the cleaning mechanism using the conventional cleaning pads 105 and 106, it is difficult to achieve both the cleaning ability and the durability.
[0006]
Further, as another problem, there is a phenomenon in which foreign matter scraped off by cleaning with a cleaning pad cannot be completely removed from the wire and remains, resulting in uneven discharge at that portion. The remaining foreign matter has a small adhesive force since it has been scraped off from the wire once. If the discharge operation is performed for a while, the foreign matter is blown off by high-frequency vibration generated at the time of discharge. However, the time required to recover varies depending on the adhesive force of the foreign matter. Even if the discharge operation is performed for several minutes, the foreign matter slightly remains, and uneven discharge occurs in that part, and a raindrop image may be formed. .
This problem tends to occur particularly when a cleaning pad having a surface coated with an abrasive is used. FIG. 10 is a front view showing a state of a conventional cleaning pad coated with an abrasive. As shown in FIG. 10, the cleaning pad 107 coated with the abrasive 108 has a rough surface, and thus has a high ability to scrape foreign matter adhered to the wire 101. However, since a portion that is not in close contact with the wire 101 is generated, the capability of wiping the foreign material is low, and the scraped foreign material 109 remains without being removed from the wire 101, and uneven discharge occurs at that portion.
[0007]
SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and an object of the present invention is to provide an image forming apparatus including a cleaning unit having high cleaning ability and excellent durability.
Another object of the present invention is to provide an image forming apparatus provided with a cleaning unit having high cleaning ability and capable of preventing discharge unevenness after cleaning.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, an image forming apparatus according to claim 1 includes a corona charger for applying a voltage to a thin wire to perform a corona discharge to impart an electrostatic charge to a member to be charged, and rubs a foreign matter attached to the fine wire. In the image forming apparatus, the cleaning means includes a cleaning member in which a portion in contact with the fine line is formed in a groove shape.
An image forming apparatus according to claim 2, comprising: a corona charger for applying a voltage to the fine wire to perform corona discharge to impart an electrostatic charge to a member to be charged; and a cleaning means for rubbing and cleaning foreign matter attached to the fine wire. In the image forming apparatus provided with the cleaning device, the cleaning unit includes a wiping member for wiping foreign substances adhered to the fine line, and a wiping member for wiping foreign substances remaining on the fine line after the wiping.
The image forming apparatus according to claim 3, wherein the cleaning means cleans the fine line while moving in parallel with the stretching direction of the fine line, and the scraping member is provided on the upstream side in the cleaning direction. And the above-mentioned wiping member is provided on the downstream side in the cleaning direction to be integrally formed.
An image forming apparatus according to a fourth aspect is the image forming apparatus according to the first, second or third aspect, wherein a surface of the cleaning member or the scraping member is coated with an abrasive.
In the image forming apparatus according to the first aspect and the image forming apparatus according to the fourth aspect having the configuration of the apparatus, a portion of the cleaning member that contacts the thin line is formed in a groove shape, and the thin line is formed in the groove portion of the cleaning member during cleaning. Addictive. If a combination of at least two such cleaning members is moved along a thin line, or if the cleaning member is moved along a thin line while rotating about the thin line, the cleaning member contacts the entire circumference of the thin line. can do. Therefore, the cleaning member can be cleaned in a state where there is no uneven contact with the fine wire, and the cleaning ability can be enhanced. Further, since the cleaning member can contact the entire circumference of the fine wire as described above, the cleaning member does not need to be formed of a soft material, and can be formed of a hard material. Therefore, the durability of the cleaning member can be improved.
Further, in the image forming apparatus according to the second aspect and the image forming apparatuses according to the third and fourth aspects having the configuration of the apparatus, the foreign matter adhered to the fine wire with a strong adhesive force is first scraped off by the scraping member. The foreign matter scraped off by the scraping member may adhere to the fine line again, but the foreign matter adhered to the fine line again has a weak adhesive force. Therefore, the reattached foreign matter can be easily removed by the wiping member. As described above, since the foreign matter attached to the fine wire is cleaned in two stages, the foreign matter hardly remains on the fine wire. Therefore, the cleaning means has a high cleaning ability and can prevent discharge unevenness due to remaining foreign matter after cleaning.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a color image forming apparatus to which the present invention is applied will be described.
FIG. 1 is a schematic configuration diagram illustrating the configuration of the image forming apparatus according to the present embodiment. First, the configuration and operation of the image forming apparatus will be described with reference to FIG. The belt-shaped photoconductor 1 is uniformly charged by a corona charger 2 described later while being rotated clockwise, and is then scanned and exposed by a laser beam based on image information by an optical writing unit 3 so that the surface is exposed. An electrostatic latent image is formed. The image information to be exposed here is monochrome image information obtained by decomposing a desired full-color image into black, cyan, magenta, and yellow color information. The electrostatic latent image formed on the photoconductor 1 is developed by the developing units 4K, 4C, 4M, and 4Y with black, cyan, magenta, and yellow toners as respective predetermined developers. Each color image is formed.
[0010]
The respective color images formed on the photoreceptor 1 are sequentially transferred by the primary transfer bias roller 6 for each single color of black, cyan, magenta, and yellow onto the intermediate transfer belt 5 that is driven to rotate counterclockwise. The black, cyan, magenta, and yellow images superimposed on the intermediate transfer belt 5 are collectively transferred to transfer paper 9 fed from a paper feed cassette 8 by a secondary transfer bias roller 7. After the completion of the transfer, the transfer paper 9 is fixed with the toner image by the fixing device 10 and discharged outside the apparatus as a full-color printer.
[0011]
The toner on the photoconductor 1 that has not been transferred to the intermediate transfer belt 5 is removed by the cleaning blade of the photoconductor cleaning unit 11. Further, the toner on the intermediate transfer belt 5 that has not been transferred onto the transfer paper 9 is removed by the intermediate transfer belt cleaning unit 12.
[0012]
(Embodiment 1)
In the image forming apparatus according to the first embodiment, the corona charger 2 has the following features in addition to the configuration of the image forming apparatus. FIG. 2A is a cross-sectional view illustrating a schematic configuration of a wire and a cleaning pad during cleaning, and FIG. 2B is a cross-sectional view illustrating a schematic configuration of a wire and a cleaning pad during cleaning. FIG. 3 is a cross-sectional view showing a schematic configuration of the wire and the cleaning pad at the time of non-cleaning.
The corona charger 2 according to the present embodiment applies a high voltage to a thin wire 20 stretched with a constant force in a charging case to cause corona discharge, and causes the photoconductor 1 as a member to be charged to have an electrostatic charge. And charged. As shown in FIGS. 2 and 3, the cleaning means includes a pair of cleaning pads 21 (21a, 21b), which are cleaning members, and a pad holding member 22 that holds the cleaning pads 21. As shown in FIG. 3, the cleaning pads 21a and 21b are formed in a wedge-shaped groove shape at a portion in contact with the wire 20, and are coated with abrasives 23a and 23b.
[0013]
As shown in FIG. 3, when the wire 20 is discharging, the cleaning pads 21 a and 21 b configured as described above stand by at a position separated from the wire 20, and discharge stability is maintained. Then, the pad holding member 22 moves from one end to the other end of the corona charger 2 in parallel with the direction in which the wire 20 is stretched at a predetermined timing when a predetermined number of sheets are output. In accordance with the movement of the pad holding member 22, the cleaning pads 21a and 21b move while sandwiching the wire 20 in the groove-shaped portion and scraping off the foreign matter adhering to the wire 20. Since the cleaning pad 21 is cleaned by sandwiching the wire 20 between the groove-shaped portions, the cleaning pad 21 can be uniformly cleaned over the entire circumference of the wire 20 and has a high cleaning ability.
Further, since the pair of cleaning pads 21 can contact uniformly over the entire circumference of the wire 20 as described above, the cleaning pads 21 can be made of a hard material. As the base material of the cleaning pad 21, a material harder than the foreign matter adhering to the wire 20, for example, a metal such as SUS, a resin such as polycarbonate, a high hardness and high durability rubber or a cloth resistant to abrasion can be used. Conventionally, a pad made of a soft material such as sponge or rubber is used so that the pad is in contact with the entire circumference of the wire. However, there has been a problem that the pad is cut off during cleaning and the pad is cut off. On the other hand, since the cleaning pad 21 according to the present embodiment can be made of a hard material, the durability of the cleaning pad 21 can be improved and the life of the apparatus can be extended. Further, by coating the portion of the cleaning pad 21 that comes into contact with the wire 20 with the abrasive 23, foreign matter adhering to the wire 20 can be scraped and cleaned regardless of the material of the base material.
[0014]
In the present embodiment, two cleaning pads 21 are used, but three or more cleaning pads may be used in combination. Further, the pad holding member 22 according to the present embodiment is configured to move the pair of cleaning pads 21 in one direction along the wire 20, but the cleaning direction is not limited to this. The pad holding member 22 may move the pair of cleaning pads 21 along the wire 20 while rotating the pair of cleaning pads 21 around the wire 20.
[0015]
(Embodiment 2)
In the image forming apparatus according to the second embodiment, the corona charger 2 has the following features in addition to the configuration of the image forming apparatus. FIG. 4 is a front view showing a schematic configuration of a wire and a cleaning pad during cleaning.
As shown in FIG. 4, the corona charger 2 according to the present embodiment includes a pair of cleaning pads 24 (24a, 24b) as cleaning means, and a pad holding member 25 that holds the cleaning pads 24. The cleaning pads 24a and 24b are integrally formed with abrasive pads 26a and 26b, which are scraping members whose surfaces are coated with an abrasive 28, and rubber pads 27a and 27b, which are wiping members made of rubber having good surface properties. Have been. The pair of abrasive pads 26 are located on the upstream side in the moving direction of the pad holding member (hereinafter referred to as the cleaning direction), and the pair of rubber pads 27 are located on the downstream side in the cleaning direction.
[0016]
When the wire 20 is discharging, the cleaning pad 24 thus configured is on standby at a position separated from the wire 20 to maintain the discharge stability. Then, the pad holding member 25 moves from one end of the corona charger 2 to the other end in parallel with the direction in which the wire 20 is stretched at a predetermined timing when a predetermined number of sheets are output. In accordance with the movement of the pad holding member 25, the cleaning pads 24a and 24b move while scraping foreign substances adhered to the wire 20. At this time, first, foreign matter adhered to the wire 20 with a strong adhesive force is scraped off by the pair of abrasive pads 26 on the upstream side in the cleaning direction, and then foreign matter scraped off by the pair of rubber pads 27 on the downstream side in the cleaning direction. . The foreign matter scraped off by the abrasive pad 26 may adhere to the wire 20 again, but the adhesive force of the foreign matter adhered to the wire 20 again is weak. The reattached foreign matter can be easily removed by the rubber pad 27. As described above, since the foreign matter adhering to the wire 20 is cleaned in two stages, the foreign matter hardly remains on the wire 20. Therefore, discharge unevenness immediately after cleaning can be eliminated, and the wire 20 can be quickly returned to the original state.
[0017]
As described above, in the image forming apparatus according to the first embodiment, since the groove shape is formed on the cleaning pad 21 as the cleaning member, the cleaning ability and durability of the cleaning pad 21 are high, and the life of the apparatus is extended. It is possible to plan.
In the image forming apparatus according to the second embodiment, the cleaning pad 24 as a cleaning unit includes an abrasive pad 26 as a scraping member and a rubber pad 27 as a wiping member. Therefore, the cleaning ability of the cleaning pad 24 is high, and uneven discharge after cleaning can be prevented.
Further, in the image forming apparatus according to the second embodiment, since the cleaning pad 24 in which the abrasive pad 26 and the rubber pad 27 are integrally formed is used, the apparatus can be simplified.
Further, in the image forming apparatus according to the present embodiment, since the surface of the cleaning pad 21 or the abrasive pad 26 is coated with the abrasive, the foreign matter adhering to the wire 20 is scraped and cleaned regardless of the material of the pad. be able to.
[0018]
【The invention's effect】
According to the present invention, there is an excellent effect that an image forming apparatus provided with a cleaning unit having high cleaning ability and excellent durability can be provided.
Further, according to the present invention, there is an excellent effect that it is possible to provide an image forming apparatus provided with a cleaning unit having a high cleaning ability and capable of preventing uneven discharge after cleaning.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment.
FIG. 2A is a cross-sectional view illustrating a schematic configuration of a wire and a cleaning pad during cleaning of the corona charger according to the first embodiment, and FIG. 2B is a front view illustrating a schematic configuration of the wire and the cleaning pad during cleaning. FIG.
FIG. 3 is a sectional view showing a schematic configuration of a wire and a cleaning pad when the corona charger is not cleaned.
FIG. 4 is a front view showing a schematic configuration of a wire and a cleaning pad of the corona charger according to the second embodiment during cleaning.
FIG. 5 is an explanatory diagram illustrating the principle of a corona charger.
FIG. 6A is a cross-sectional view illustrating a configuration of a conventional cleaning mechanism, and FIG. 6B is a front view.
FIG. 7 is a sectional view showing a state of a conventional cleaning pad and a wire having a hard surface.
8A is a cross-sectional view showing a state of a conventional soft cleaning pad and a wire, and FIG. 8B is a front view.
FIG. 9 is a cross-sectional view illustrating a state of the cleaning pad in which the pad has been cut.
FIG. 10 is a front view showing a state of a conventional cleaning pad coated with an abrasive.
[Explanation of symbols]
Reference Signs List 1 photoconductor 2 corona charger 20 wires 21, 24 cleaning pad 22, 25 pad holding members 23, 28 abrasive 26 abrasive pad 27 rubber pad

Claims (4)

An image forming apparatus comprising: a corona charger that applies a voltage to a thin wire to perform corona discharge to impart an electrostatic charge to a member to be charged; and a cleaning unit that rubs and cleans foreign matter attached to the fine wire.
The image forming apparatus according to claim 1, wherein the cleaning unit includes a cleaning member in which a portion that contacts the fine line is formed in a groove shape. An image forming apparatus comprising: a corona charger that applies a voltage to a thin wire to perform corona discharge to impart an electrostatic charge to a member to be charged; and a cleaning unit that rubs and cleans foreign matter attached to the fine wire.
The image forming apparatus according to claim 1, wherein the cleaning unit includes a wiping member for wiping foreign matter adhered to the fine line, and a wiping member for wiping foreign matter remaining on the fine line after the wiping. 3. The image forming apparatus according to claim 2,
The cleaning means cleans the fine line while moving in parallel with the stretching direction of the fine line, and the cleaning means is provided integrally with the wiping member provided upstream in the cleaning direction and the wiping member provided downstream in the cleaning direction. An image forming apparatus comprising: The image forming apparatus according to claim 1, 2 or 3,
An image forming apparatus, wherein an abrasive is coated on a surface of the cleaning member or the scraping member.

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