JP2007101683A - Cleaning device and image forming apparatus using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning device which has excellent cleaning performance by securely removing toner on a detoning rotary body and performing electrostatic transfer of toner stuck to a cleaning rotary body to the side of the detoning rotary body always stably; and also to provide an image forming apparatus using the same. <P>SOLUTION: The cleaning device is equipped with the cleaning rotary body 2 which collects waste toner remaining on a toner image carrier 1 and the detoning rotary body 3 which is arranged opposite to the cleaning rotary body 2 and to which the waste toner on the cleaning rotary body 2 is electrostatically transferred. The detoning rotary body 3 has a conductive core material 3b and a coating layer 3a covering the core material 3b, and the coating layer 3a satisfies the condition that (a) the volume resistivity is ≥109 Ωcm, (b) the dynamic hardness is ≥20, and (c) the surface roughness is ≤5 μm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cleaning device that is used in an image forming apparatus such as a copying machine or a printer and that cleans image-forming particles remaining on an image carrier, and in particular, the cleaning rotator collects using a detoning rotator. The present invention relates to a cleaning device of a type that removes residues on an image carrier and an improvement of an image forming apparatus using the cleaning device.

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, taking an electrophotographic method as an example, as a cleaning device for cleaning toner remaining on the surface of an image carrier such as a photosensitive drum or an intermediate transfer belt, for example, a photosensitive device is used. It is generally known to scrape residual toner on a photosensitive drum by bringing an elastic blade such as urethane rubber into contact with the surface of the photosensitive drum (see Patent Document 1).
By the way, in recent years, small-diameter toner has been used in order to increase the resolution of an image formed by an image forming apparatus.
In a system using such a small diameter toner, when the cleaning device provided with the elastic blade described above is used, the small diameter toner slips through the blade and is rubbed between the photosensitive drum and the blade to form a thin film. It was found that there was a problem that it became fixed as soon as it turned.

Therefore, in order to solve such problems, a cleaning brush as a cleaning rotating body that collects residual toner on the photosensitive drum in the vicinity of the photosensitive drum and a rod-like member (flicker) on which the brush tip of the cleaning brush can be struck And the residual toner on the photosensitive drum is attached to the cleaning brush, and the tip of the cleaning brush hits the flicker bar so that the toner attached to the cleaning brush is struck down. A technique has been proposed in which toner on a cleaning brush is removed (see Patent Document 2).
According to such a prior art, it is possible to prevent a problem that the toner on the photosensitive drum is thinned and the toner is fixed.
However, in a system using small-diameter toner, when such a cleaning device equipped with a cleaning brush and a flicker bar is used, since the weight of one particle of the small-diameter toner is small and sufficient centrifugal force does not work, the small-diameter toner Does not move to the tip of the cleaning brush, but accumulates on the brush without being knocked off by the flicker bar, resulting in a problem that toner recoverability with respect to the residual toner on the photosensitive drum is lowered.

As a technique for solving the above problems, a metal roll (detoning roll) to which a voltage having a polarity opposite to that of the toner is applied is disposed in the vicinity of the cleaning brush, and the toner adhering to the cleaning brush is statically placed on the metal roll. There is a method in which the toner is electrically transferred and the toner on the surface of the metal roll is scraped off by a plate-like member such as a blade or a scraper (see Patent Document 3).
According to such a method, the metal roll electrostatically adsorbs the toner on the cleaning brush, and the toner on the metal roll can be removed by strongly pressing the scraper against the surface of the metal roll. The toner recoverability with respect to the attached waste toner can be improved.

JP 61-032880 (Example, Fig. 1) JP 56-138769 A (Detailed Description of the Invention, FIG. 3) JP-A-57-185468 (Detailed Description of the Invention, FIG. 2)

However, when such a method is used, a voltage is constantly applied to the metal roll, and an electrostatic force that adsorbs the toner is constantly acting. Therefore, particularly in a system using a small particle size toner, There was a problem of so-called filming in which the toner on the roll was not completely recovered by the scraper, but was thinned and fixed when rubbed with the scraper on the metal roll. If toner adheres to the surface of the metal roll in this way, the surface resistance of the metal roll increases, and the electric field for electrostatically transferring waste toner from the cleaning brush to the metal roll side becomes weak. A technical problem has been found that the waste toner on the brush cannot be collected.
In particular, such a technical problem is remarkable in a system using a low melting point toner from the viewpoint of energy saving.

  The present invention has been made to solve the above technical problem, and reliably removes the toner on the detoning rotator, so that the toner adhering to the cleaning rotator is always stably removed from the detoning rotator side. The present invention provides a cleaning device having good cleaning performance and an image forming apparatus using the same.

That is, according to the present invention, as shown in FIG. 1A, the cleaning rotator 2 that collects the waste toner remaining on the toner image carrier 1, the cleaning rotator 2 and the cleaning rotator 2 are arranged opposite to each other. A detoning rotator 3 to which the waste toner is electrostatically transferred. The detoning rotator 3 includes a conductive core member 3b and a coating layer 3a covering the core member 3b. The coating layer 3a is a. A volume resistivity of 10 ⁹ Ω · cm or more, b. The dynamic hardness is 20 or more, c. It is characterized by satisfying that the surface roughness is a maximum height of 5 μm or less.

In such a technical means, the toner image carrier 1 to be cleaned is not only an image forming carrier such as a photoreceptor or a dielectric on which a toner image is formed and supported, but also the toner image is transferred to a recording material. In addition, an intermediate transfer body temporarily held in an intermediate stage before recording and a recording material conveyance body for conveying a toner image transferred onto the recording material are also included.
The cleaning rotator 2 may be appropriately selected such as a brush shape or a roll shape.
Further, the cleaning rotator 2 and the detoning rotator 3 may be in contact or non-contact.
Furthermore, the core material 3b of the detoning rotating body 3 only needs to be conductive, and aluminum or the like may be appropriately selected.

Here, “the volume resistivity is 10 ⁹ Ω · cm or more” is a lower limit value of the dielectric. By using the dielectric as described above, the coating layer 3a can have a function as a dielectric layer, and partial charging and partial neutralization can be performed.
Further, “dynamic hardness is 20 or more” is a boundary at the lower limit of hardness that can avoid unnecessary wear when the cleaning member 4 such as a scraper is used. The dynamic hardness 20 here corresponds to, for example, a phenol resin.
Furthermore, the “surface roughness is a maximum height of 5 μm or less” means that the upper limit of the maximum height Rz as the surface roughness necessary for ensuring the cleaning performance when the cleaning member 4 such as a scraper is used. It is a boundary.
In the present invention, the coating layer 3a of the detoning rotating body 3 may be appropriately selected as long as it has a resistance condition, a hardness condition, and a surface roughness condition, but amorphous silicon is used as a particularly preferable aspect. Photosensitive layer.

  Further, in order to electrostatically transfer the waste toner on the cleaning rotator 2 to the detoning rotator 3, for example, an electric field is applied by applying a bias between the cleaning rotator 2 and the detoning rotator 3. It may be allowed to act, or the surface of the detoning rotator 3 may be charged, and may be appropriately selected.

Further, the present invention preferably includes a cleaning member 4 that is disposed in contact with the periphery of the detoning rotator 3 and cleans waste toner on the detoning rotator 3.
The cleaning member 4 may be appropriately selected such as a roll shape or a blade shape as long as the toner can be removed. In addition, when a scraper is used for the cleaning member 4, for example, a metal such as SUS can be used, but the present invention is not limited to this, and a non-metal such as a hard resin or ceramics may be selected as appropriate.

  Furthermore, as a preferred embodiment of the present invention, in the embodiment in which the coating layer 3a of the detoning rotator 3 is provided with a toner carrying layer capable of carrying toner, the detoning rotator 3 is disposed so as to face the detoning rotator 3 and at least with the cleaning rotator 2. The charger 5 that holds the surface of the detoning rotator 3 in a charged state at the opposed position, and the downstream side of the detoning rotator 3 around the detoning rotator 3 and the cleaning rotator 2. And a static eliminator 6 that neutralizes the surface of the detoning rotator 3.

In this case, the detoning rotator 3 may be appropriately selected as long as the coating layer 3a is provided with a toner carrying layer capable of carrying toner by charging, such as a photosensitive layer or a dielectric layer.
Further, the static eliminator 6 may be appropriately selected as long as the surface of the detoning rotating body 3 can be neutralized. For example, the static eliminator 6 may be neutralized by applying an AC bias, or may be neutralized by a neutralizing roll.
In particular, in the present invention, it is preferable to use a photosensitive member for the detoning rotator 3 and to use a device for irradiating the detoning rotator 3 with light to the static eliminator 6. In this case, as a particularly preferable aspect, as described above, an aspect in which amorphous silicon is used for the coating layer 3a of the detoning rotating body 3 can be mentioned.

Furthermore, it is preferable that the static eliminator 6 neutralizes the surface potential of the detoning rotator 3 to less than 100V. In this way, by setting the potential of the detoning rotator 3 after static elimination small, the force (Coulomb force) that the toner after static elimination adheres to the detoning rotator 3 can be weakened, and the The toner can be removed. In particular, when the surface potential after static elimination exceeds 50 V, the toner can be effectively removed by using the cleaning member 4 whose tip is not deformed, such as a scraper.
The charger 5 may be appropriately selected as long as it keeps the surface of the detoning rotating body 3 charged, such as a corotron or a charging roll.

Further, the present invention includes an aspect in which a plurality of cleaning rotators 2 are provided and a detoning rotator 3 is provided for each cleaning rotator 2. According to this, for example, the present invention can be applied to a mode in which the cleaning rotator 2 that collects regularly charged toner and the cleaning rotator 2 that collects reverse polarity toner are connected together.
Furthermore, the present invention is not limited to the above-described cleaning device, but also targets an image forming apparatus using the same.

According to the cleaning device of the present invention, since the coating layer satisfying the predetermined resistance condition, hardness condition and surface roughness condition is provided on the surface of the detoning rotator, the toner releasability is improved and the cleaning rotator is provided. The adhered toner can be constantly and electrostatically transferred to the detoning rotator side, and a cleaning device having good cleaning performance can be provided.
In other words, when the volume resistivity of the coating layer of the detoning rotating body is 10 ⁹ Ω · cm or more, it has a function as a dielectric and can be partially charged and partially discharged, and can be transported with toner and separated with toner. Can be improved.
In particular, since the dynamic hardness of the coating layer of the detoning rotating body is 20 or more, it is possible to use a cleaning member having a high removal performance in which the tip is kept in an undeformed state, such as a scraper. Peelability can be improved.
Furthermore, since the surface roughness of the coating layer of the detoning rotating body has a maximum height of 5 μm or less, it has sufficient smoothness and can improve toner releasability.

According to the image forming apparatus using such a cleaning device, a high-quality image with good cleaning performance can be easily obtained.
In particular, the embodiment using a low melting point toner is extremely effective.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
Embodiment 1
FIG. 2 shows an image forming apparatus according to the first embodiment to which the present invention is applied.
In the figure, the color image forming apparatus according to the present embodiment forms yellow (Y), magenta (M), cyan (C), and black (K) color component toner images by, for example, electrophotography. A plurality of image forming units 10 (specifically, 10Y, 10M, 10C, and 10K), and an intermediate transfer belt 20 that sequentially transfers (primary transfer) each color component toner image formed by each image forming unit 10; A secondary transfer device 30 that collectively transfers (secondary transfer) the superimposed image transferred onto the intermediate transfer belt 20 onto a sheet P as a recording material, and a fixing device 40 that fixes the collectively transferred image onto the sheet P; The sheet P is provided with a sheet conveyance path 50 through which the sheet P is conveyed through the secondary transfer device 30 to the fixing device 40.

In the present embodiment, the image forming unit 10 for each color component includes the yellow image forming unit 10Y, the magenta image forming unit 10M, the cyan image forming unit 10C, and the black image forming unit 10K from the upstream side in the transport direction of the intermediate transfer belt 20. Arranged in order.
Further, as shown in FIG. 3, each image forming unit 10 has a uniform charger 12 on which the photosensitive drum 11 is charged and a static charge on the photosensitive drum 11 around the photosensitive drum 11 as an image carrier. A laser exposure device 13 in which an electrostatic latent image is written, a developing device 14 in which each color component toner is accommodated and an electrostatic latent image on the photosensitive drum 11 is visualized, and each color component toner image on the photosensitive drum 11 Is transferred to the intermediate transfer belt 20, a primary transfer device (primary transfer roll) 15, a cleaning device 16 that removes residual toner on the photosensitive drum 11, a toner charge adjuster 17 that adjusts the charge of the toner before cleaning, and the like. These electrophotographic devices are sequentially arranged.

Here, each developer 14 stores toner of each color component, Y toner in the yellow image forming unit 10Y, M toner in the magenta image forming unit 10M, C toner in the cyan image forming unit 10C, and a black image. K toner is used for each of the forming units 10K.
Further, a voltage having a polarity opposite to the charging polarity of the toner is applied to the primary transfer roll 15, whereby the toner images on the photosensitive drum 11 are sequentially electrostatically attracted to the intermediate transfer belt 20. A superimposed toner image is formed on the intermediate transfer belt 20.

  The intermediate transfer belt 20 is stretched over a plurality of support rolls 21 to 23. The support roll 21 is a drive roll for the intermediate transfer belt 20, the support roll 22 is a driven roll, and the support roll 23 is described later. It is provided as a backup roll for the next transfer device 30 (see FIG. 2).

  Further, the secondary transfer device 30 includes a secondary transfer roll 31 disposed in pressure contact with the toner carrying surface side of the intermediate transfer belt 20 and a counter electrode of the secondary transfer roll 31 disposed on the back surface side of the intermediate transfer belt 20. A backup roll 32 (also used as the support roll 23) is provided, and a bias having the same polarity as the charging polarity of the toner is stably applied to the backup roll 32.

  Further, the fixing device 40 has a heating roll 41 whose surface is heated by a heating source and rotates so as to be drivable, and a pressure which is arranged in pressure contact with the heating roll 41 and conveys the paper P between the heating roll 41. A roll 42 is provided, and the toner image is fixed on the paper P by passing the paper P between the heating roll 41 and the pressure roll 42.

  Further, the paper transport path 50 feeds the paper P from a paper tray (not shown) to the secondary transfer device 30 via the registration roll 51, and transports the paper P after the secondary transfer. It is formed so as to be guided to the belt 52 and transported to the fixing device 40 by the transport belt 52.

Further, the cleaning device 16 which is a characteristic point of the present embodiment will be described in detail with reference to FIG.
In the figure, a cleaning device 16 is provided with a plurality of cleaners connected in a cleaning housing 70, and is charged to a normal polarity on the photosensitive drum 11, for example, a negative polarity, on the upstream side in the rotation direction of the photosensitive drum 11. A negative cleaner 80 that collects the residual toner, and another polarity on the photosensitive drum 11 such as a positive polarity residual toner (reverse polarity toner) downstream of the negative cleaner 80 in the rotation direction of the photosensitive drum 11. A positive polarity cleaner 90 to be collected and a waste toner storage unit 100 for storing all the recovered waste toner are provided.

Further, the negative cleaner 80 is disposed so as to face the photosensitive drum 11 and reversely rotates (Against) at the facing portion, and the cleaning brush 81 has a surface behind the cleaning brush 81. For example, a photosensitive layer is provided as a toner carrying layer on the covering layer 82a, and a detoning roll 82 (corresponding to a detoning rotating body) that rotates in the same direction at a portion facing the cleaning brush 81 is disposed. Yes. Further, a charging roll 83 for charging the surface of the detoning roll 82 is provided below the detoning roll 82. Further, behind the detoning roll 82, for example, a static eliminator 84 such as an exposure device that neutralizes the surface of the detoning roll 82, and the detoning roll 82 around the detoning roll 82 are arranged downstream from the static elimination position and detoning. A scraper 85 made of metal such as SUS (corresponding to a cleaning member) is disposed so as to scrape the waste toner on the detoning roll 82 in contact with the surface of the roll 82.
In the present embodiment, the static eliminator 84 is used to neutralize the surface potential of the detoning roll 82 to less than 100V.

Further, in the present embodiment, the cleaning brush 81 is connected to a bias power supply 87 to which a positive voltage having the opposite polarity to the negative polarity toner on the photosensitive drum 11 is applied. Therefore, the surface of the cleaning brush 81 is kept at a high potential with respect to the photosensitive drum 11.
The detoning roll 82 includes a conductive core member 82 b and an insulating coating layer 82 a, and the surface of the detoning roll 82 is positively charged by the charging roll 83, and the surface potential is the surface potential of the cleaning brush 81. The potential is kept higher than that (see FIG. 5A). As a result, the negative residual toner on the photosensitive drum 11 can be electrostatically transferred to the cleaning brush 81 and the detoning roll 82.

Further, the positive polarity cleaner 90 has a cleaning brush 91 disposed opposite to the negative polarity cleaner 80 around the photosensitive drum 11 so as to be opposed to Against, and a toner is carried on the coating layer 92a on the surface behind the cleaning brush 91. A photosensitive layer as a layer is provided, and a detoning roll 92 that rotates with Gainst with respect to the cleaning brush 91 is provided. Further, a charging roll 93 is provided above the detoning roll 92. In addition, a static eliminator 94 such as an exposure unit is disposed behind the detoning roll 92, and a metal scraper 95 such as SUS is disposed downstream of the exposure position.
In the present embodiment, a static eliminator 94 is used that neutralizes the surface potential of the detoning roll 92 to an absolute value of less than 100V.

Furthermore, in the present embodiment, the cleaning brush 91 is connected to a bias power source 97 to which a negative voltage having the opposite polarity to the reverse polarity toner (positive toner) on the photosensitive drum 11 is applied. Yes. Therefore, the surface of the cleaning brush 91 is kept at a low potential with respect to the photosensitive drum 11.
The detoning roll 92 includes a conductive core 92 b and an insulating coating layer 92 a, and its surface is negatively charged by the charging roll 93, and the surface potential is the surface potential of the cleaning brush 91. The potential is kept lower than that (see FIG. 5A). Thereby, the reverse polarity toner on the photosensitive drum 11 can be electrostatically transferred to the cleaning brush 91 and the detoning roll 92.
The negative cleaner 80 and the positive cleaner 90 may be provided in separate housings, and the arrangement positions of the constituent members and the rotation directions of the rotary members are not limited to this. However, it may be selected as appropriate.

Further, the waste toner storage unit 100 includes a storage housing 101 formed of a part of the cleaning housing 70, and the waste toner is collected in the storage housing 101 for transporting the waste toner to a recovery box (not shown). An auger 102 is provided.
A partition plate 105 that partitions the negative polarity cleaner 80 and the positive polarity cleaner 90 is disposed in the center of the cleaning housing 70. The partition plate 105 prevents the waste toner collected by the positive polarity cleaner 90 from directly scattering on the negative polarity cleaner 80.

In particular, in the present embodiment, as shown in FIG. 5A, the detoning roll 82 (92) includes a conductive core material 82b (92b) made of, for example, aluminum, and the core material 82b (92b). Is coated with a coating layer 82a (92a) made of amorphous silicon.
This covering layer 82a (92a) is a test load of 2.0 kgf (19.6 mN) and a load speed of 0.0145 gf (with a ridge angle of 115 ° using a Shimadzu dynamic ultra-small hardness meter DUH-201S. This satisfies the hardness condition that the measured value (dynamic hardness) under the measurement condition of 0.1421 mN) / sec is 20 or more.

In general, the measurement principle of the surface microhardness is as shown in FIG. 5B, in which a needle-shaped indenter 89 having a predetermined shape is pressed to a predetermined load F (mN) on the surface portion of the coating layer 82a (92a). When the indentation depth D (μm) of the indenter 89 at that time is set, if the surface microhardness is hard, the biting depth D is reduced accordingly, and the surface microhardness (dynamic hardness) DH is, for example, Represented by a mathematical formula.
DH = α · F / D
However, α is a coefficient determined in advance by the shape of the indenter 89, measurement conditions, and the like.

Further, the maximum height Rz is measured in accordance with JIS B 0601. The cross-sectional curve of the covering layer 82a (92a) is extracted as the reference length L, and the distance between the peak portion and the valley bottom portion of the portion is extracted. Is measured in the direction of the vertical magnification of the cross-sectional curve and expressed in micrometers (μm) (see FIG. 5A).
In the present embodiment, the maximum height Rz of the coating layer 82a (92a) is set to 5 μm or less.

Furthermore, the covering layer 82a (92a) is an insulator having a volume resistivity of 10 ⁹ Ω · cm or more, and the covering layer 82a (92a) has a function as a dielectric layer. Neutralization can be performed. In other words, in the present embodiment, the surface of the detoning roll 82 (92) can be charged by the facing portion of the cleaning brush 81 (91), and further, the static electricity can be removed by the facing portion of the neutralizer 84 (94). Can be made. Therefore, an electrostatic force that attracts toner can be applied during toner conveyance, while the electrostatic force can be canceled during toner collection.
In this case, the volume resistivity of the covering layer 82a (92a) including amorphous silicon may be 10Ω ¹¹ · cm or more, preferably 10 ¹³ Ω · cm or more, more preferably 10 ¹⁵ Ω · cm.

Here, as a manufacturing method of the coating layer 82a (92a), a plasma CVD method is typically given, and in this embodiment, for example, a high frequency plasma CVD method is employed.
Further, the static eliminator 84 (94) is used to neutralize the surface potential of the detoning roll 82 (92) to an absolute value of less than 100V.

Next, an image forming process of the color image forming apparatus according to the present embodiment will be described with reference to FIGS.
Now, when a start switch (not shown) is turned on, a predetermined image forming process is executed.
Specifically, for example, when this color image forming apparatus is configured as a digital color copying machine, a document set on a document table (not shown) is read by a color image reading device, and the read signal is image signal processing means. Are converted into digital image signals, temporarily stored in the memory, and toner images of the respective colors are formed based on the stored digital image signals of four colors (Y, M, C, K). .

That is, the image forming units 10 (specifically, 10Y, 10M, 10C, and 10K) are driven based on the digital image signals of the respective colors input from the image signal processing means. In each image forming unit 10, an electrostatic latent image corresponding to the digital signal is written by a laser exposure unit 13 on the photosensitive drum 11 uniformly charged by the uniform charger 12.
Each electrostatic latent image is developed by a developing device 14 containing toner of each color to form a toner image of each color.
In the case where the color image forming apparatus is configured as a printer or the like, the toner image of each color may be formed based on an image signal input to the image signal processing means from the outside.

The toner image formed on each photoconductor drum 11 is transferred from the photoconductor drum 11 to the surface of the intermediate transfer belt 20 by the primary transfer roll 15 at a primary transfer position where each photoconductor drum 11 and the intermediate transfer belt 20 are in contact with each other. Transferred sequentially in the order of YMCK.
Further, the toner remaining on the photosensitive drum 11 after the primary transfer is cleaned by a cleaning device 16 as will be described later.

The toner image primarily transferred to the intermediate transfer belt 20 in this way is superimposed on the intermediate transfer belt 20 and conveyed to the secondary transfer position as the intermediate transfer belt 20 rotates.
On the other hand, the paper P is supplied to the secondary transfer position at a predetermined timing, and the secondary transfer roll 31 nips the paper P with respect to the backup roll 32.

Then, at the secondary transfer position, the toner image carried on the intermediate transfer belt 20 is collectively transferred to the paper P (secondary transfer) by the action of the transfer electric field formed between the secondary transfer roll 31 and the backup roll 32. Transferred).
As described above, the sheet P on which the toner image is transferred is conveyed to the fixing device 40 by the conveying belt 52 and the toner image is fixed.

In particular, in the present embodiment, since the cleaning device 16 includes the detoning roll 82 (92) having the coating layer 82a (92a) provided with amorphous silicon, the cleaning performance is extremely good.
That is, residual toner on the photosensitive drum 11 is cleaned between the cleaning brush 81 of the negative cleaner 80 and the photosensitive drum 11 when the photosensitive drum 11 is conveyed to a position facing the cleaning device 16 by rotation of the photosensitive drum 11. When a positive electric field acts on the brush 81 side, the negative polarity toner is transferred to the cleaning brush 81 side (see FIG. 4).

On the other hand, of the residual toner on the photosensitive drum 11, reverse polarity toner (positive toner) passes through a portion facing the cleaning brush 81 to which negative toner can be adsorbed, and is opposed to the cleaning brush 91. It is conveyed to. At this time, a negative electric field acts on the cleaning brush 91 side between the cleaning brush 91 and the photosensitive drum 11, so that the reverse polarity toner can be transferred to the cleaning brush 91 side.
The negative polarity toner transferred to the negative polarity cleaner 80 and the reverse polarity toner transferred to the positive polarity cleaner 90 have different polarities, but the basic action is substantially the same. Only the basic action will be described.

  In the present embodiment, the toner adhering to the cleaning brush 81 in the negative cleaner 80 is conveyed to a position facing the detoning roll 82 by the rotation of the cleaning brush 81. At this time, the surface potential of the detoning roll 82 facing the cleaning brush 81 is maintained at a higher potential than the surface of the cleaning brush 81 by the charging roll 83. Since a positive electric field acts on the detoning roll 82 side, the negative polarity toner on the cleaning brush 81 is transferred to the detoning roll 82 side.

Further, the toner transferred onto the detoning roll 82 is conveyed to a position facing the static eliminator 84 by the rotation of the detoning roll 82. With this static eliminator 84, the surface potential at the portion of the detoning roll 82 facing the static eliminator 84 and the waste toner at that portion are neutralized to less than 100V.
The discharged toner is conveyed to a position facing the scraper 85 by the rotation of the detoning roll 82 and is easily scraped off by the scraper 85, so that the surface of the detoning roll 82 is always kept clean.
Further, the removed waste toner is stored in the storage housing 101 and is transported to the recovery box (not shown) by the recovery auger 102.

As described above, according to the present embodiment, since the coating layers 82a and 92a of the detoning rolls 82 and 92 have high resistance, charging and discharging can be performed on necessary portions. Can be improved. Furthermore, in the present embodiment, since the coating layers 82a and 92a have high hardness and smoothness, they are excellent in mechanical toner releasability. As a result, a stable electric field can always be applied between the detoning rolls 82 and 92 and the cleaning brushes 81 and 91, and the waste toner adhering to the cleaning brushes 81 and 91 can be reliably transferred. it can.
Therefore, the cleaning property with respect to the photosensitive drum 11 is kept good.

Embodiment 2
FIG. 6 shows an outline of a detoning roll 120 according to Embodiment 2 to which the present invention is applied. In this figure, the present embodiment is configured in substantially the same manner as the cleaning device 16 (see FIG. 4) of the first embodiment, but the covering of the detoning roll 120 used for the negative polarity cleaner 80 and the positive polarity cleaner 90 is provided. The difference from Embodiment 1 is that the layer 120a is provided with a phenol resin.
Components similar to those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted here.

In the present embodiment, the detoning roll 120 is made of a conductive core material 120b and a coating made of, for example, a phenol resin that covers the aluminum core material 120b and has a smooth surface, for example. And a layer 120a. The coating layer 120a is formed by mixing dielectric powder (for example, BaTiO ₃ or the like) with an insulating phenol resin, and is formed as a dielectric layer.
The covering layer 120a is a dielectric that satisfies the resistance condition of a volume resistivity of 10 ⁹ Ω · cm or more, satisfies the hardness condition that the dynamic hardness is 20 or more, and has a maximum height Rz of It satisfies the surface roughness condition of 5 μm or less.

The detoning roll 120 may be manufactured by, for example, applying a phenol resin mixed with the dielectric powder as the coating layer 120a to a mirror-finished aluminum core member 120b, and then applying the coating. A method of polishing the surface of the layer 120a can be given.
Further, in the present embodiment, a static elimination roll 121 is used as the static elimination member. This static elimination roll 121 neutralizes the surface potential of the detoning roll 120 to an absolute value of less than 100V.

Next, the operation in the present embodiment will be described.
In the present embodiment, for example, negative polarity toner adhering to the cleaning brush 81 is conveyed to a position facing the detoning roll 120 by the rotation of the cleaning brush 81. At this time, the surface potential of the detoning roll 120 facing the cleaning roll 81 is maintained at a higher potential, for example, than the surface of the cleaning brush 81 by the charging roll 83, and the detoning roll 120 and the cleaning brush 81 In the meantime, a positive electric field acts toward the detoning roll 120 side. By this electric field, the negative toner on the cleaning brush 81 is transferred to the detoning roll 120 side.

Further, the toner transferred onto the detoning roll 120 is conveyed to a position facing the neutralizing roll 121 by the rotation of the detoning roll 120 while being attracted to the detoning roll 120. Then, the charge removal roll 121 removes the surface potential at the portion of the detoning roll 120 facing the charge removal roll 121 and the waste toner at that portion to less than 100V.
The discharged toner is conveyed to a position facing the scraper 85 by the rotation of the detoning roll 120 and is easily scraped off by the scraper 85.

  As described above, according to the present embodiment, the detoning roll 120 is provided with the coating layer 120a made of a phenol resin that satisfies the resistance condition, the hardness condition, and the surface roughness condition. The same effects as in the first embodiment can be obtained.

Example 1
This example has the same configuration as that of the negative cleaner according to the first embodiment. From the relationship between the surface potential of the detoning roll after charging and the surface potential of the detoning roll after neutralization, the waste on the detoning roll The removal performance for toner was examined.
Here, the cleaning conditions in the present embodiment are as follows.
a. Detoning roll / surface: photosensitive layer with amorphous silicon (volume resistivity = 10 ¹¹ Ω · cm or more, dynamic hardness = 650, maximum height Rz = 9 nm)
-Core material: Aluminum-Roll diameter: 15mm
・ Rotation speed: 75mm / s
-Surface potential after charging: +250 to 850V
-Surface potential after exposure (after static elimination): 0 to 200V
b. Cleaning brush / material: fiber nylon 2d
・ Diameter: 17mm
・ Fiber length: 5mm
・ Cleaning brush potential: + 250V
c. Static eliminator / exposure device: LED exposure d. Scraper / Material: SUS304
・ Thickness: 0.08mm
Contact pressure: 6.6 g / mm
-Contact angle: 32 ° (doctor method)
Free length (cross-sectional length from the fixed part to the contact part): 8.1 mm
e. Toner / Binder: Crystalline polyester Melting point: 90 ° C.
Storage modulus (30 ° C., 1 rad / s): 2 × 10 ⁶ Pa
Loss elastic modulus (30 ° C., 1 rad / s): 2 × 10 ⁶ Pa
Charge amount: -40 μC / g

Further, a conventional configuration in which a scraper was brought into contact with the detoning roll and scraped only by a mechanical action was also examined as a comparative example.
The cleaning conditions of the comparative example are as follows.
a. Detoning roll, surface: phenolic resin, core material: SUS
・ Roll diameter: 20mm
b. Scraper / Material: SUS
・ Thickness: 0.08mm
Contact pressure: 6.6 g / mm
・ Contact direction: Doctor method

FIG. 7 shows the result of cleaning performance when the printing speed is 266 m / s.
In the figure, the detoning potential indicates the surface potential of the detoning roll after charging in this embodiment, and indicates the potential applied to the core of the detoning roll in the comparative example. Is.
This figure shows the removal performance with respect to the waste toner. In this embodiment, the surface potential of the detoning roll after exposure (after neutralization) is set to 0 V to 200 V, and the toner is scraped only by mechanical action. About the comparative example to take, the result at the time of setting a detoning potential to 250V-850V by 100V space | interval is shown.

As shown in the figure, in this example, regardless of the surface potential of the detoning roll after charging, if the surface potential after neutralization is 200 V or more, a strong Coulomb force acts on the toner on the detoning roll. Therefore, the toner could not be removed by the scraper, and filming occurred on the entire surface of the detoning roll.
Further, when the surface potential after static elimination was 100 V or more, filming was observed on a part of the detoning roll.
Furthermore, according to the comparative example, in addition to the constant coulomb force acting on the toner, since the surface of the detoning roll is rough, there is a gap at the contact portion between the detoning roll and the scraper. It was confirmed that filming occurred on the entire surface of the detoning roll.
On the other hand, it was confirmed that if the surface potential after static elimination is less than 100 V, particularly 50 V or less, the Coulomb force of the toner on the detoning roll is weakened and can be easily scraped off by a scraper.

Example 2
In the present embodiment, the relationship between the detoning efficiency and the detoning potential is examined with the same configuration as that of the first embodiment. In addition, the thing similar to the conventional structure of Example 1 was also investigated as a comparative example.
In FIG. 8, the detoning efficiency is expressed as a ratio of the amount of toner moved to the detoning roll when the residual toner on the photosensitive drum is moved to the cleaning brush and then the cleaning brush makes one round, that is, This is expressed as ((amount of toner on the detoning roll transferred from the cleaning brush) / (amount of toner on the cleaning brush transferred from the photosensitive drum)) during one round of the cleaning brush.

As shown in the figure, it was confirmed that in this example, detoning efficiency equal to or higher than that of the comparative example was obtained in all regions where the detoning potential was 250 to 850V.
According to this embodiment, since the detoning roll is provided with a coating layer having resistance conditions, hardness conditions, and surface roughness conditions, good toner peelability can be obtained and the surface of the detoning roll can always be kept clean. And good detoning efficiency was confirmed.

Example 3
In this example, the removal performance of the waste toner on the detoning roll due to the difference in the coating layer was examined with the same configuration as that of the negative cleaner of the first and second embodiments.
The coating layers used in this example are as follows.
Amorphous silicon (volume resistivity = 10 ¹¹ Ω · cm or more, dynamic hardness = 650, maximum height Rz = 9 nm)
・ Phenolic resin I (volume resistivity = 10 ^10-13 , dynamic hardness = 20, maximum height Rz = 5 μm)
・ Phenolic resin II (volume resistivity = 10 ^10-13 , dynamic hardness = 20, maximum height Rz = 50 μm (unpolished))

FIG. 9 shows the result of the removal performance with respect to the waste toner.
For “Phenolic resin II”, the surface roughness condition was not satisfied, and filming was observed in part of the detoning roll.
On the other hand, “Phenolic resin I” has a smooth surface, satisfies the resistance condition, hardness condition and surface roughness condition. It was.
Furthermore, filming did not occur with “amorphous silicon”, and the best results were obtained.

It is explanatory drawing which shows the outline | summary of the cleaning apparatus which concerns on this invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram illustrating an image forming apparatus according to a first embodiment to which the present invention is applied. 2 is an explanatory diagram illustrating an image forming unit according to Embodiment 1. FIG. FIG. 3 is an explanatory diagram illustrating the cleaning device according to the first embodiment. (A) is explanatory drawing which shows the detoning roll used in Embodiment 1, (b) is explanatory drawing which shows the measuring method of dynamic hardness. It is explanatory drawing which shows the detoning roll used in Embodiment 2. It is a table | surface which shows the result of Example 1 with a comparative example. It is the graph which represented the result of Example 2 with the comparative example. 10 is a table showing the results of Example 3.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Toner image carrier, 2 ... Cleaning rotator, 3 ... Detoning rotator, 3a ... Coating layer, 3b ... Core material, 4 ... Cleaning member, 5 ... Charger, 6 ... Static eliminator

Claims (8)

A cleaning rotator for collecting waste toner remaining on the toner image carrier;
A detoning rotator which is disposed opposite to the cleaning rotator and to which waste toner on the cleaning rotator is electrostatically transferred,
The detoning rotating body includes a conductive core material and a coating layer that covers the core material,
The coating layer is
a. The volume resistivity is 10 ⁹ Ω · cm or more,
b. The dynamic hardness is 20 or more,
c. The surface roughness is a maximum height of 5 μm or less,
A cleaning device that satisfies the above requirements. The cleaning device according to claim 1.
And a cleaning member disposed in contact with the periphery of the detoning rotator to clean the waste toner on the detoning rotator. The cleaning device according to claim 1.
A cleaning apparatus, wherein the coating layer of the detoning rotating body is a photosensitive layer using amorphous silicon. In the cleaning device according to claim 1 or 2, comprising a toner carrying layer capable of carrying toner as a coating layer of the detoning rotating body.
A charger disposed opposite to the detoning rotator and holding the surface of the detoning rotator in a charged state at least at a position facing the cleaning rotator;
A cleaning device comprising: a discharger disposed on the downstream side of a position where the detoning rotator and the cleaning rotator face each other around the detoning rotator and removing the surface of the detoning rotator. apparatus. The cleaning device according to claim 4.
A cleaning device, wherein the detoning rotator is a photosensitive member, and the static eliminator irradiates the detoning rotator with light. The cleaning device according to claim 4.
The cleaning device, wherein the static eliminator sets the surface potential of the detoning rotating body after static elimination to less than 100V. The cleaning device according to claim 1.
A cleaning apparatus having a plurality of cleaning rotators, wherein a detoning rotator is provided for each cleaning rotator.   An image forming apparatus comprising the cleaning device according to claim 1.

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