JP4366209B2 - Cleaning device - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile machine that forms an image by electrophotography, and more particularly, a magnet that uses magnetic toner and non-magnetic toner as a developer and further removes residual toner on an image carrier. The present invention relates to an image forming apparatus including a cleaning device having a roller.

  As an image forming apparatus such as a copying machine, a printer, or a facsimile that forms an image by electrophotography, a toner image electrostatically formed on the surface of a photosensitive drum as an image carrier is electrostatically applied to a recording material such as paper. In general, an image forming apparatus for transferring images is generally used.

  In such an image forming apparatus, it is necessary to sufficiently clean the residual toner that is not transferred to the recording material side at the time of transfer and remains on the photosensitive drum as it is for the next image formation, As a cleaner for this purpose, a cleaning blade made of an elastic material such as urethane rubber is pressed into contact with the surface of the photosensitive drum to remove residual toner, and has already been widely put into practical use.

  However, from the viewpoint of extending the life of the photosensitive drum, in an image forming apparatus using an a-Si photosensitive drum, not only residual toner but also organic substances to be deposited and high-voltage members (such as a charger) in the apparatus exist. Various foreign matters that may adhere to the photosensitive drum and cause deterioration of image quality, such as the corona product, need to be removed, but such foreign matters could not be completely removed by the cleaning blade alone.

  Therefore, particularly in the case of an image forming apparatus using an a-Si photosensitive member and a one-component magnetic toner, as shown in FIG. 6, a cleaning blade that scrapes off foreign matters such as transfer residual toner remaining on the surface of the photosensitive drum 100. In some cases, the magnet roller 101 may be disposed in the vicinity of the cleaning blade together with the cleaning blade 103. That is, by using the magnetic property of the toner, the magnetic brush 102, which is a toner layer of a certain thickness formed on the magnet roller 101 with the toner once collected, is used to rub and remove various foreign matters as described above. Yes. The magnetic brush 102 is uniformly formed by a toner coat amount regulating member 105.

  Further, when the toner is scraped off from the photosensitive drum 100 by the cleaning blade 103, the scraped toner is scraped by a lateral running phenomenon (a phenomenon that the toner is pushed out to the end of the cleaning blade 103 along the edge of the cleaning blade 103). The taken toner leaks from both ends of the cleaning blade 103 and adheres to both ends of the magnet roller 101. For this reason, conventionally, the toner attached to the end of the magnet roller 101 is scraped off by the end scraper 104 provided on the end of the magnet roller 101.

  In such a configuration, in addition to the foreign matter removing action, the magnetic brush 102 supplies toner to the edge of the cleaning blade 103 little by little so that no toner is present on the surface of the photosensitive drum 100. It is possible to prevent so-called “blade turning”. Further, by applying a mechanical force to the toner electrostatically adhering to the surface of the photosensitive drum 100, the adhesion force of the toner to the photosensitive drum 100 is reduced and the toner can be easily removed by the cleaning blade 103. There is an advantage, and an image forming apparatus that uses only one-component magnetic toner to obtain a monochrome image has a certain effect.

  On the other hand, the color toner in a multicolor image forming apparatus of two or more colors is generally configured by mixing a dye and a pigment in a transparent resin in order to make the color of a printed image clear. In many cases, the toner is a non-magnetic toner. In addition, when the configuration uses all non-magnetic toner including black toner, the residual toner on the surface of the photosensitive drum is often removed with the above-described cleaning blade configuration.

  However, since one-component magnetic toner does not require toner density control and the developing device has a simpler configuration than two-component, there are cases where it is used as a black toner. When the cleaning device 107 having the magnet roller 101 is applied, the color toner is not attracted to the magnet roller 101, and it cannot be avoided that a problem occurs in the cleaning function.

  Further, in order to match the cleaning action with the non-magnetic toner, it is possible to eliminate the magnet roller 101 and rely only on the cleaning blade 103 because of the advantages of the magnet roller 101 as described above. It is not a good idea to obtain an image because the frequency is considered to be the largest. In other words, it is desired to clean the non-magnetic toner without impairing the effect that the magnet roller 101 exhibits in cleaning the magnetic toner.

Therefore, when the non-magnetic toner is collected in the cleaning device provided with the magnet roller 101, the non-magnetic toner first adheres to the magnetic toner on the magnet roller 101 by an action such as electrostatic attraction force. Although the toner is removed from the top 100, when a certain amount of non-magnetic toner is supplied, the toner is further removed without being captured and overflows and scatters to the outside. For this reason, in the collection configuration of the magnetic / nonmagnetic toner mixture, a toner scattering prevention member 107 (flexible member, so-called rake sheet; hereinafter referred to as rake sheet) is disposed under the magnet roller 101 and is separated. This prevents the non-magnetic toner from overflowing to the outside. (For example, see Patent Document 1)
JP 2004-21141 A

  However, it has been found that by arranging the scooping sheet 107, the residual toner on the photosensitive drum 100 is scraped off by the scooping sheet 107, which may cause a phenomenon of toner dropping, that is, so-called dripping. This is a phenomenon peculiar to the cleaning device having the magnet roller 101, and the positional relationship among the magnet roller 101, the rake sheet 107, and the cleaner container 109 is greatly influenced.

  As shown in FIG. 7, the magnetic brush 102 formed on the photosensitive drum 100 and the magnet roller 101 forms a magnetic pool 108 between the photosensitive drum 100 and the magnet roller 101. The mug chamber 108 is pressed against the photosensitive drum 100 by the rotation of the magnet roller 101. When the mug pool 108 is applied to the tip of the scooping sheet 107, the scooping sheet 107 is pressed against the photosensitive drum 100, and the residual toner on the photosensitive drum 100 is scraped off by the abdomen of the scooping sheet 107. Will occur.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to optimize the positional relationship between the magnet roller, the rake sheet, and the cleaner container in a cleaning device having the magnet roller and the rake sheet, and to drop the toner. Another object of the present invention is to provide a cleaning device having a structure for preventing so-called lid dropping and an image forming apparatus provided with such a cleaning device.

To achieve the above object, the present invention provides a rotatable image carrier and a magnetic brush provided on the surface of the image carrier so as to be rotatable in a direction opposite to the rotation direction of the image carrier. Cleaning means having a magnet roller for removing toner;
A toner scattering preventing member disposed upstream of the magnet roller with respect to the rotation direction of the image carrier to prevent the toner removed by the cleaning means from scattering outside the cleaning device; and both ends of the magnet roller A regulating member that regulates the amount of toner formed on the magnet roller,
In a cleaning device having
The distance F between the magnet roller and the image carrier is 0.85 to 1.45 mm, the peripheral speed ratio J of the magnet roller to the image carrier is 90 to 330%, and the magnet of the restriction member The width in the roller rotation axis direction is 8 mm or more, the magnetic force T of the magnet roller is 700 to 1300 gauss, and
When the distance between the tip of the toner scattering prevention member and the magnet roller is H (mm),
1.03 87 ln (J) −1.45 73 ≦ H ≦ T / 100,
By satisfying the above, the contact portion of the toner scattering preventing member with the image carrier is prevented from entering the toner reservoir formed between the image carrier and the magnet roller, and the magnet roller The toner that has been released from the toner and dropped onto the toner scattering prevention member can be pulled back by the magnetic force of the magnet roller.

  According to the present invention, in a cleaning device having a magnet roller and a rake sheet, it is possible to prevent toner dropping, so-called lid dropping, by optimizing the positional relationship between the magnet roller, the rake sheet, and the cleaner container.

  Hereinafter, the present invention will be described based on the illustrated embodiments.

<Embodiment>
Exemplary embodiments of the present invention will be described in detail below with reference to the drawings. This cleaning device is suitable for use in a cleaner that removes residual toner remaining on the surface of a photoreceptor in an electrophotographic image forming apparatus such as a laser beam printer, a copying machine, or a laser facsimile.

  It should be noted that the dimensions, materials, shapes, and relative arrangements of the component parts described in the following embodiments are intended to limit the scope of the present invention only to those unless otherwise specified. is not.

  First, the overall configuration of the image forming apparatus according to the present embodiment will be described with reference to FIG. FIG. 1 is a schematic sectional view of the image forming apparatus.

  The image forming apparatus shown in FIG. 1 forms an electrostatic latent image on a photosensitive member as an image carrier, develops the latent image with a developer (toner), and transfers it to a sheet to form a full color image. This is an electrophotographic color image forming apparatus.

  An image reading unit is provided on the upper part of the apparatus main body, and the original S placed on the original table glass 30 is exposed and scanned by the exposure lamp 31 so that the reflected light images from the original S are mirrors 12a, 12b, 12c. , And the lens 13 to focus on the full color sensor 14 to obtain a color separation image signal.

  The color-separated image signal is processed by a video processing unit through an amplifier circuit (not shown) and sent to an image forming unit.

  The image forming unit includes a photoreceptor 15 that is an image carrier. Further, around the photoconductor 15, a pre-exposure lamp 16, a corona charger 17, a laser exposure optical system 18 as an exposure means, a potential sensor 19, a cleaning device 24, a fixed black developing device 21K, and three rotatable units. Color developing units 20Y, 20M, and 20C and an intermediate transfer member 9 are disposed. Here, the developing devices 20Y, 20M, and 20C use non-magnetic toner, and the developing device 21K uses magnetic toner.

  When an image formation start signal is input to the image forming unit, the photoconductor 15 is rotationally driven in the direction of arrow A by a driving unit (not shown). Then, the residual potential of the photoconductor 15 is neutralized by the pre-exposure lamp 16 and uniformly charged by the corona charger 17.

  In the laser exposure optical system 18, the image signal from the image reading unit is converted into an optical signal by a laser output unit (not shown), and the converted laser beam is reflected by the rotary polygon mirror 18a and passes through the lens 18b and the mirror 18c. And projected onto the cylindrical surface of the photoreceptor 15. In this way, a light image is irradiated for each separated color, and an electrostatic latent image is formed on the photoreceptor 15.

  The three rotating developing devices 20Y, 20M, and 20C are detachably held by a developing rotary 23 that rotates about a rotating shaft 22, respectively. At the time of image formation, each developing device is rotated around the rotating shaft 22 while being held by the developing rotary 23, the predetermined developing device stops at a position facing the photoconductor 15, and the developing sleeve is further moved to the photoconductor. After being positioned so as to face 15 with a small interval, a visible image is formed corresponding to the electrostatic latent image on the photoreceptor 15.

  At the time of color image formation, the development rotary 23 rotates every rotation of the intermediate transfer member 9, and the development process is performed in the order of the magenta developing unit 20M, the yellow developing unit 20Y, the cyan developing unit 20C, and then the black developing unit 21K.

  Since the intermediate transfer member 9 receives the toner image on the photosensitive member 15 visualized by each developing device during the color image forming operation four times (each image of four colors of M, Y, C, and K), the photosensitive member is subjected to multiple transfer. Rotate in the direction of arrow B in synchronization with the outer peripheral speed of 15. The intermediate transfer body 9 that has undergone multiple transfer nips and conveys the transfer material 11 by a transfer roller 10 to which a voltage is applied, thereby simultaneously transferring multiple color toner images on the intermediate transfer body 9 onto the transfer material 11. The transfer material 11 after the transfer is sent to a fixing device which is the next process.

  The transfer material 11 holding the toner image is conveyed by a fixing roller 26 and a pressure roller 27 and is subjected to heat and pressure. As a result, the toner is fixed to the transfer material 11.

  Next, the configuration of the cleaning device according to the present embodiment will be described with reference to FIG. FIG. 2 is a schematic sectional view of the cleaning device.

  The cleaning device includes a main unit D and a rake sheet unit (receiving member unit) E that is detachable from the main unit D.

  The main unit D generally includes a cleaner container 25 having an opening 25b facing the surface of the photoconductor 15 on a side surface thereof, and a cleaning blade 7 as a cleaning member that scrapes off residual toner on the surface of the photoconductor 15 above the opening 25b. And a container end seal (not shown) disposed at both ends of the cleaning blade 7.

  The cleaner container 25 is a box that forms the outline of the cleaning device. The cleaner container 25 contains the cleaning roller 7, the magnet roller 5, the waste toner conveying screw 6, and other components, and the residual toner collected from the photoconductor 15. Take an accepted role.

  The cleaning blade 7 made of urethane rubber is fixed to a blade swing plate 33, and the blade swing plate 33 is supported so as to be swingable about a swing fulcrum shaft 34. Further, a pressure spring 32 is stretched around the blade swing plate 33, and the cleaning blade 7 is urged against the photosensitive member 15 with a predetermined pressure by the spring force of the pressure spring 32.

  One edge of one edge of the cleaning blade 7 attached to the frame is pressed against the surface of the photoconductor 15 to scrape off the residual toner after transfer.

  A magnet roller 5 is disposed on the upstream side of the cleaning blade 7 in the traveling direction of the photoconductor 15 and is driven in the same direction as the photoconductor 15 as indicated by an arrow C direction. When magnetic toner and non-magnetic toner are supplied by the developing devices 20Y, 20C, 20M, and 21K, a part of the collected magnetic toner is collected on the surface of the magnet roller 5 and is determined by the photosensitive member 15 and has a constant thickness. The magnetic brush 5a which is a layer is formed.

  As the magnet roller 5 rotates, the toner layer reaches a position facing the photoconductor 15, and forms a mag reservoir 5 b upstream of the magnet roller to surely rub the surface of the photoconductor 15. The toner layer is scraped off at both ends of the magnet roller 5 with a scraper 28 to adjust the amount of the magnet reservoir 5b. The toner scraped off is discharged to the outside by the waste toner conveying screw 6.

  The rake sheet 1 slidably contacts the surface of the photoreceptor 15 at the lower part of the opening 25b of the cleaner container 25 (below the cleaning blade 7), receives residual toner scraped off by the cleaning blade 7, and receives the cleaner from the opening 25b. The collected toner is introduced into the container 25.

  On both sides of the opening 25b, a container end seal (not shown) attached to the main unit D and an end seal (not shown) attached to the rake sheet unit E are crushed between the cleaning device and the photoconductor 15. The sealing material 3 is installed between the cleaner container 25 and the scooping sheet unit E, and the gap between the apparatus and the photoconductor 15 is sealed.

  As a result, the nonmagnetic toner separated from the magnet roller 5 and the scattered nonmagnetic toner do not spill from the cleaner container 25.

  Next, with reference to FIG. 3, the positional relationship among the rake sheet, the mag pool, and the cleaner container according to this embodiment will be described.

  The position where the tip of the rake sheet 1 does not enter the toner reservoir 5b formed between the photosensitive member 15 and the magnet roller 5 and the toner that has been released from the magnet roller 5 and dropped onto the rake sheet 1 Place it in a position where it can be pulled back by magnetic force.

The parameters that determine the amount of the mug reservoir 5b include the following.
1. Magnet roller-photoreceptor distance F
2. Peripheral speed ratio J between magnet roller and photoconductor
3. 3. Magnet roller end scraper width Magnet roller magnetic force T
Among these, 1 is 0.85 to 1.45 mm, 2 is 30 to 330% (to the photosensitive member), 3 is 8 mm or more in width, and 4 is about 700 to 1300 G.

The trouble when the upper limit and the lower limit are exceeded in 1-4 will be briefly described.
1. Upper limit: The side running phenomenon of the toner hardly occurs, and the toner stays and drops.
Lower limit: The rubbing of the photoconductor 15 by the toner is increased, and the photoconductor 15 is scratched.
2. Upper and lower limits: Toner re-coating on the photoconductor 15 is defective and cleaning is defective. Further, the peripheral speed difference is increased, and the photoreceptor 15 is damaged.
3. Lower limit: The scraping ability is lost, and the toner stays and drops.
4). Upper limit: The rubbing of the photoconductor 15 by the toner is increased, and the photoconductor 15 is scratched.
Lower limit: The lateral running phenomenon of the toner hardly occurs, and the toner stays and drops off.

  As described above, if any one of the four items does not satisfy the condition, a cleaning defect due to a photoconductor scratch or a toner re-coating defect occurs. Therefore, in this embodiment, 1 is 1.15 mm, 2 is 90%, 3 is 10 mm, and 4 is 1000 G.

[Upper limit of rake sheet tip]
As a result of experiments, in the configuration of the present embodiment, if the distance between the magnet roller 5 and the tip of the rake sheet 1 is 10 mm or less, the recovered magnetism that is separated from the magnet roller 5 and dropped onto the rake sheet 1 portion as shown in FIG. It was found that the toner can be returned again by the magnetic force of the magnet roller 5. Further, the magnetic force of the magnet roller 5 is proportional. Therefore, if the distance between the magnet roller 5 and the tip of the rake sheet 1 is H (mm), a relationship of H ≦ 1/100 × T [T: magnetic force of the magnet roller (G)] is obtained. By satisfying this relationship, the rake sheet 1 is not buried with the collected toner, and toner leakage to the outside of the cleaner container 25 can be prevented.

[Lower limit of rake sheet tip]
Among the above four conditions, items other than 2 have low sensitivity with respect to the formation of the mag pool 5b in the actual use range. Therefore, with respect to “2. Peripheral speed ratio J between the magnet roller and the photosensitive member”, which has a wide condition range and has a large influence on the amount of the magnet reservoir 5b, actual data from 30% to 330%, which is the usable area, is shown in FIG. Show. The X axis is the peripheral speed ratio of the magnet roller 5 to the photoreceptor 15 and the Y axis is the distance K between the magnet roller 5 and the magnet reservoir 5b. If 100% = constant velocity, or less, the magnet roller 5 is slower than the photoreceptor 15, and if it is more than that, the magnet roller 5 is faster.

  As shown in FIG. 5, the peripheral speed ratio increases and the mag pool 5b increases. That is, it means that the magnet reservoir 5b becomes larger as the peripheral speed of the magnet roller 5 becomes higher than the photosensitive member 15. Therefore, from this result, the relational expression of K = 1.0387Ln (J) -1.4573 is established using the peripheral speed ratio J as a parameter. In this embodiment, a circumferential speed ratio of 90% is adopted. Therefore, when the distance H between the tip of the rake sheet 1 and the magnet roller 5 is 3.3 mm or more, the mag pool 25b is not covered with the tip of the rake sheet 1. No (K ≦ H).

  Further, as shown in FIG. 3, the tip of the rake sheet 1 is arranged below the toner receiving portion 25a in the gravity direction so that even when the amount of the mag pool is increased, the tip of the toner receiving portion 25a is regulated. Therefore, it is possible to prevent the mug pool 5b from directly covering the tip of the rake sheet 1.

  As described above, in a cleaning device having a magnet roller and a rake sheet, it is possible to prevent toner dropping, so-called lid dropping, by optimizing the positional relationship between the magnet roller, the rake sheet, and the cleaner container.

1 is a schematic sectional view of an image forming apparatus according to an embodiment of the present invention. It is a schematic structure sectional view of a cleaning device concerning an embodiment of the present invention. 1 is an enlarged sectional view 1 of a cleaning device according to an embodiment of the present invention. FIG. 3 is an enlarged cross-sectional view 2 of the cleaning device according to the embodiment of the present invention. It is verification data concerning the embodiment of the present invention. It is a schematic structure sectional view of a cleaning device in a conventional example. It is an expanded sectional view of the cleaning apparatus in a prior art example.

Explanation of symbols

1 Rake sheet (flexible member)
2 Sheet support plate 3 Sealing material 5 Magnet roller 5a Magnetic brush 5b Mug reservoir 6 Waste toner conveying screw 7 Cleaning blade (cleaning member)
DESCRIPTION OF SYMBOLS 9 Intermediate transfer body 10 Transfer roller 11 Transfer material 12a, 12b, 12c Mirror 13 Lens 14 Full color sensor 15 Photoconductor (image carrier)
16 Pre-exposure lamp 17 Corona charger 18 Laser exposure optical system 18a Rotating polygon mirror 18b Lens 19 Potential sensor 20Y Developer (yellow developer)
20C developer (cyan developer)
20M Developer (Magenta Developer)
21K developer (black developer)
DESCRIPTION OF SYMBOLS 22 Rotating shaft 23 Developing rotary 24 Cleaning device 25 Cleaner container 25a Toner receiving portion 25b Opening portion 26 Fixing roller 27 Pressing roller 28 Scraper 30 Platen glass 31 Exposure lamp 32 Pressing spring 33 Blade swing plate 34 Swing fulcrum shaft D Main unit E Scoop sheet unit (receiving member unit)
S manuscript

Claims (2)

A rotatable image carrier, and a cleaning means provided to be rotatable in a direction opposite to the rotation direction of the image carrier, and having a magnet roller for removing toner on the image carrier by a magnetic brush formed on the surface. ,
A toner scattering preventing member disposed upstream of the magnet roller with respect to the rotation direction of the image carrier to prevent the toner removed by the cleaning means from scattering outside the cleaning device; and both ends of the magnet roller A regulating member that regulates the amount of toner formed on the magnet roller,
In a cleaning device having
The distance F between the magnet roller and the image carrier is 0.85 to 1.45 mm, the peripheral speed ratio J of the magnet roller to the image carrier is 90 to 330%, and the magnet of the restriction member The width in the roller rotation axis direction is 8 mm or more, the magnetic force T of the magnet roller is 700 to 1300 gauss, and
When the distance between the tip of the toner scattering prevention member and the magnet roller is H (mm),
1.03 87 ln (J) −1.45 73 ≦ H ≦ T / 100,
By satisfying the above, the contact portion of the toner scattering preventing member with the image carrier is prevented from entering the toner reservoir formed between the image carrier and the magnet roller, and the magnet roller The cleaning device is characterized in that the toner released from the toner and falling onto the toner scattering prevention member can be pulled back by the magnetic force of the magnet roller.   The cleaning device includes a toner storage portion that stores the toner removed by the cleaning unit, and the toner storage portion is a container having an opening facing the surface of the image carrier, and the image of the toner scattering prevention member. The cleaning device according to claim 1, wherein a contact portion to the carrier is arranged on a lower side in a vertical direction than an end portion of the opening.

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