JP4712596B2 - Cleaning device and image forming apparatus - Google Patents

Description

  The present invention relates to a cleaning device for an electrophotographic image forming apparatus and an image forming apparatus. The present invention also relates to a cleaning device such as a copying machine and a laser printer and an image forming apparatus.

In the image forming apparatus, in order to remove the toner remaining on the surface of the image carrier, there is a system in which the toner is removed with a rotated fur brush and then cleaned by bringing a cleaning blade made of an elastic material into contact therewith. This method is a method that combines the advantages of the conventional fur brush cleaning method and the cleaning blade method, and has recently been adopted in high-speed machines near 100 sheets / minute.
However, this cleaning method may cause a print quality problem depending on the time, environment, printing rate, and the like. One of them is toner fixing to the image carrier. The problem is that when the additive externally added to the toner is released and adheres to the surface of the image carrier, the toner accumulates starting from the adhered additive, and the accumulated toner is blocked by the additive. The toner gradually adheres to the surface of the image carrier. As a result, dirt appears on the background portion of the toner image, and the image quality is remarkably deteriorated. Therefore, conventionally, this has been dealt with by replacing the image carrier.
For the purpose of extending the life of the photoreceptor used in the image forming apparatus, it is widely practiced to provide a hard surface layer at least on the outermost side of the photosensitive layer to improve the wear resistance. However, when a photoconductor having a high surface hardness is applied to the image forming apparatus, it is effective for the wear resistance of the photoconductor, but foreign matter tends to adhere to the surface layer of the photoconductor. Examples of the foreign matter include a nitrogen compound formed by combining ozone generated in the charging device and nitrogen in the air and a paper component of the paper. Since these components have high hygroscopicity, when they adhere to the photoreceptor, the surface of the photoreceptor absorbs moisture under a high temperature and high humidity to lower the resistance, and the charge retention ability is partially reduced. In such a case, the surface charge leaks when forming the latent image, and the latent image pattern is destroyed or the latent image cannot be formed. Therefore, a phenomenon called image flow occurs. . This image flow is not only bad in appearance but also cannot be discriminated when it occurs in a thin line portion such as a character portion or a barcode, and is a fatal image defect.

As a countermeasure, Patent Document 1 proposes a technique in which a cleaning member is constituted by a cleaning blade with an abrasive (hereinafter referred to as a polishing blade) to remove foreign matters on the surface of the photoreceptor. Also, in order to prevent the wear of the image carrier and the generation of scratches, which are a concern when the polishing blade is always in contact with the image carrier for a long time, a contact / separation mechanism is provided on the polishing blade, The contact is made according to the number of sheets.
Patent Document 2 discloses conditions (rubber hardness, average particle diameter of abrasive particles, etc.) under which the second cleaning blade that polishes the surface of the image carrier is most effective. However, no consideration is given to the case where foreign matter adheres to the second cleaning blade, and there is a high possibility that streak-like scratches in the circumferential direction of the image carrier are likely to occur.

The polishing blade uses an elastic material such as polyurethane rubber in which an abrasive is dispersed. The edge portion is brought into contact with the photoconductor, and the fixed toner is removed by rubbing the edge portion and the photoconductor surface. . Therefore, when hard particles such as a carrier adhere to the polishing blade edge, there is a problem that a sharp flaw is caused on the surface of the photoreceptor corresponding to the portion where the carrier is attached.
Therefore, in many image forming apparatuses, the polishing blade is installed as a second cleaning blade downstream of the first cleaning blade for the purpose of mainly removing toner remaining on the photoreceptor.
However, as the carrier diameter is reduced in recent years, the amount of carrier adhesion to the photoconductor also tends to increase, and the possibility that the carrier adhering to the photoconductor slips through the first cleaning blade has increased. Further, due to the reduction in the diameter of the carrier, there is a possibility that the carrier that is not sufficiently magnetized is scattered in the image forming apparatus, and the scattered carrier reaches the vicinity of the polishing blade.

JP 2001-296781 A JP 2005-62820 A

  Therefore, the present invention has been made in view of the above problems, and the problem is that even when a small-diameter carrier is applied, the fixed toner on the surface of the photoconductor is removed without damaging the photoconductor, It is an object of the present invention to provide a cleaning device and an image forming apparatus that maintain good image quality.

The features of the present invention, which is a means for solving the above problems, are listed below.
The present invention provides a cleaning device for cleaning the surface of an image carrier provided in an image forming apparatus, comprising a first cleaning blade and a second cleaning blade in order from the upstream in the rotational direction of the image carrier. between said one cleaning blade second cleaning blade, you collecting carriers of the image bearing member surface, Ru cleaning apparatus der characterized by having a career collecting means made of a magnetic material.
The present invention is characterized in that the carrier collecting means is detachable from a cleaning device.
The present invention is characterized in that the second cleaning blade contains an abrasive and can be contacted and separated.
The present invention, the carrier, characterized in that it is a less carrier Weight average particle size 65 .mu.m.
Also, the present invention is an image forming apparatus characterized by having a cleaning apparatus of the description.

  According to the present invention, even when a small-diameter carrier is applied by the means for solving the problem, a cleaning device that removes the fixed toner on the surface of the photosensitive member and maintains good image quality without damaging the photosensitive member. In addition, an image forming apparatus can be provided.

  The best mode for carrying out the present invention will be described below with reference to the drawings. Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode of the present invention, and does not limit the scope of the claims.

  In FIG. 1, the first cleaning blade 8a is applied in a counter manner. The second cleaning blade 8b is also applied in a counter manner, and the adhering substance on the photosensitive member 1 can be removed by an impact that hits the second cleaning blade 8b, and a good removal performance can be obtained. At this time, the contact angle of the second cleaning blade 8b is preferably 5 degrees or more and 25 degrees or less. If the contact angle of the second cleaning blade 8b is less than 5 degrees, the blade becomes bumpy and the polishing function is not exhibited over time due to the creep phenomenon. On the other hand, when the angle exceeds 25 degrees, the blade is turned over due to the reverse rotation of the photosensitive member 1 at the end of the job.

The contact pressure of the second cleaning blade 8b is preferably 10 gf / cm or more and 60 gf / cm or less. If the contact pressure is less than 10 gf / cm, the contact pressure is low, so that the deposits on the photoreceptor 1 are likely to pass through the second cleaning blade 8b, and foreign matter cannot be removed sufficiently. On the other hand, if it exceeds 60 gf / cm, the film scraping amount of the photosensitive member 1 increases and the life of the photosensitive member 1 is shortened.
The amount of biting into the photoreceptor 1 of the second cleaning blade 8b obtained by the relationship between the hardness of the second cleaning blade 8b and the contact pressure is preferably 0.2 mm or more and 1.5 mm or less. By installing the second cleaning blade 8b so as to achieve the above biting amount, the role as a polishing blade for removing the deposits can be sufficiently exhibited without excessively increasing the film scraping amount of the photoreceptor 1. be able to.

  On the other hand, as shown in FIG. 2, when the first cleaning blade 8a is of the counter type and the second cleaning blade 8b is of the trailing type, the deposit removing ability on the photosensitive member 1 is slightly lowered. By the contact, the blade turning of the second cleaning blade 8b can be avoided. At this time, the contact pressure of the second cleaning blade 8b is preferably 10 gf / cm or more and 60 gf / cm or less for the same reason as in the counter-type contact. By bringing the second cleaning blade 8b into contact with the contact pressure in the above range, good foreign matter removal performance is exhibited.

  The second cleaning blade 8b is a polishing blade having an abrasive particle-containing layer made of an elastic material containing abrasive particles. In addition to the untransferred toner, inorganic fine particles detached from the toner, additives such as exuded wax, or additives such as calcium carbonate contained in recording paper dust adhere to the photoreceptor 1. These substances cause filming and eventually grow from nuclei to lumps. The second cleaning blade 8b is a polishing blade that scrapes and removes the adhering substances on the photoreceptor 1.

  The polishing blade is made by mixing abrasive particles with an elastic material such as fluoro rubber, silicone rubber, butyl rubber, butadiene rubber, isoprene rubber, urethane rubber, etc., and forming it into a sheet by centrifugal molding. It is done. As the elastic material, the above rubber material having a rubber hardness of 65 degrees or more and 85 degrees or less is preferable. This is because if the hardness is less than 65 degrees, the blade wear proceeds quickly, and if the hardness is more than 85 degrees, the blade edge tends to be chipped. More preferably, urethane rubber having the rubber hardness is used from the viewpoint of wear resistance.

  As abrasive particles, nitrides such as silicon nitride, silicates such as aluminum silicate, magnesium silicate, mica and calcium silicate, calcareous substances such as calcium carbonate and gypsum, silicon carbide, boron carbide, tantalum carbide, titanium carbide, carbonized Examples thereof include carbides such as aluminum and zirconium carbide, and oxides such as cerium oxide, chromium oxide, titanium oxide, and aluminum oxide. Among these, cerium oxide having excellent polishing power is preferable.

FIG. 3 shows an example in which a sufficiently magnetized magnetic material is installed as the carrier collecting member 15 between the first cleaning blade 8a and the second cleaning blade 8b. The collecting member 15 was arranged with a gap d = 1.5 mm apart from the photoreceptor 1 and was made of a magnetic material having a magnetic flux density of 80 mT on the surface facing the photoreceptor 1. The magnetic material of the carrier collecting member 15 is provided with a stay on a holder (sheet metal) of the second cleaning blade 8b. By using a sheet metal for the holder, the magnetic body is fixed and the holder can be easily attached and detached.
The carrier collecting member 15 can prevent the carrier from adhering to the second cleaning blade 8b and prevent the occurrence of streaky abnormal images. Further, by using a magnetic material for the carrier collecting member 15, the carrier that has passed through the first cleaning blade 8a can be collected, and the occurrence of streaky abnormal images can be prevented. Furthermore, by making the carrier collecting means 15 detachable from the cleaning device 8, the collected carrier can be easily collected and the carrier collecting means 15 can be reused.

  FIG. 4 shows the result of checking up to 100,000 prints of streak-like images with or without the carrier collecting mechanism 15. As for the streak image rank, the streak image becomes worse as the rank is lowered without rank image. Rank 4 or higher is an allowable range. At the time of printing 50,000 sheets, without the carrier collecting mechanism 15, the allowable range is almost reached, and an unacceptable level streak image is generated at the time of 100,000 sheets. On the other hand, with the carrier collecting mechanism 15, no streak image was generated up to 100,000 sheets.

  In the cleaning device shown in FIGS. 1 and 2, the second cleaning blade 8b may be in contact with the photosensitive member 1 intermittently at an appropriate timing. In this case, the second cleaning blade 8b needs to be provided with a separation mechanism using a solenoid, a cam or the like. An example in which an approach / separation mechanism is provided is shown in FIG. For the timing of intermittent contact, a mechanism for counting print coverage is provided in the image forming apparatus, and On and Off in this section are switched based on the detected value. In this example, based on the result of Table 1, it was set so as not to contact when the coverage was less than 10%, but to contact when the coverage was 10% or more. As described above, by contacting the second cleaning blade 8b only when necessary, it is possible to achieve both suppression of defects due to toner adhesion to the photosensitive member 1 and suppression of streak-like scratches on the photosensitive member 1 due to carriers. Can do.

In addition, in an image forming apparatus using a small-diameter carrier that has been increasing in recent years, it is possible to provide stable image quality without any problems by applying the cleaning device 8 of this embodiment. 6 shows the transition of the streak image rank when the carrier diameter is changed when the carrier collecting means 15 is not used, FIG. 7 shows the transition of the streak image rank when the carrier collecting means 15 is used, and FIG. The transition of the streak image rank when the carrier collecting means 15 and the second cleaning blade contacting / separating mechanism are combined is shown.
When a carrier having a particle size of 80 μm is used, the streak image rank can satisfy the allowable range regardless of the presence or absence of the carrier collecting mechanism 15, but the carrier collecting mechanism 15 is not provided for a carrier having a particle size of 65 μm or less. As the carrier diameter decreases, the streak image rank deteriorates faster. Even with these small-diameter carriers, the streak image can be maintained at an acceptable level over 100,000 prints by providing the carrier collecting mechanism 15. Further, it can be seen that the streak image is hardly generated by intermittently contacting the second cleaning blade 8b.

  The cleaning device 8 and the image forming apparatus targeted by the present invention are not limited to the configurations shown in FIGS. 1 to 4, but include an intermediate transfer member that once transfers and carries the toner image on the photosensitive member 1. Alternatively, a configuration in which a plurality of photoreceptors 1 are provided to form a multicolor image may be used.

It is a figure which shows a cleaning apparatus. It is a figure which shows a cleaning apparatus. It is a figure which shows the cleaning apparatus of this invention. It is a figure which shows the result of having confirmed the streak-like image to 100,000 prints by the presence or absence of a carrier collection mechanism. It is a figure which shows the example which provided the contact-and-separation mechanism. It is a figure which shows transition of the streak image rank at the time of shaking a carrier diameter when not using a carrier collection means. It is a figure which shows transition of the stripe image rank at the time of using a carrier collection means. It is a figure which shows transition of a streak image rank at the time of combining a carrier collection means and a 2nd cleaning blade contact-and-separation mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging device 3 Exposure device 4 Developing device 6 Transfer device 8 Cleaning device 8a First cleaning blade 8b Second cleaning blade 8e Contacting / separating cam 15 Carrier collecting member

Claims (5)

In the cleaning device for cleaning the surface of the image carrier provided in the image forming apparatus,
The cleaning device includes:
In order from the upstream in the rotational direction of the image carrier, a first cleaning blade,
A second cleaning blade;
With
Wherein between the first cleaning blade and the second cleaning blade, you collecting carriers of the image bearing member surface, the cleaning apparatus characterized by having a career collecting means made of a magnetic material. The cleaning device according to claim 1,
The cleaning device, wherein the carrier collecting means is detachable from the cleaning device. The cleaning device according to claim 1 or 2,
The cleaning apparatus, wherein the second cleaning blade contains an abrasive and can be contacted and separated . In the cleaning device according to any one of claims 1 to 3,
A cleaning device , wherein the carrier is a carrier having a weight average particle diameter of 65 μm or less . The cleaning device according to claim 1.
An image forming apparatus.

Images